China kilimoli trils lee2016

Vol. 90 No. 6 pp.1955–1975
ACTA GEOLOGICA SINICA (English Edition)
Dec. 2016
Systematic Revision of Trilobites from the Middle Ordovician
(Darriwilian) Klimoli Formation of the Zhuozishan Area, Inner
Mongolia, China
LEE Seung-Bae1, LEE Dong-Chan2,*, WOO Jusun3 and ZHANG Xingliang4
1 Geology Division, Korea Institute of Geoscience and Mineral Resources, Daejeon, 305-350, Republic
of Korea
2 Department of Earth Science Education, Chungbuk National University, Cheongju, 361-763, Republic
of Korea
3 Division of Polar Earth-System Sciences, Korea Polar Research Institute, Incheon, 406-840, Republic
of Korea
4 Early Life Institute and State Key Laboratory of Continental Dynamics, Department of Geology,
Northwest University, Xi’an 710069, China
Abstract: New morphologic information permits systematic revision of trilobites from the Middle
Ordovician Klimoli Formation of the Zhuozishan area, Ordos Basin, Inner Mongolia. The new
assemblage is composed of 10 species of the Raphiophoridae, Nileidae, Asaphidae, and Telephinidae. An
asaphid, aff. Mioptychopyge lashachungensis (previously Paraptychopyge lashachungensis) displays an
intermediate morphology between the Chinese nobiliasaphine genera Mioptychopyge and Zhenganites.
The pygidial doublure is regarded as the most significant character to differentiate Symphysurus
klimoliensis (previously Nileus klimoliensis) of the Nileidae from such closely allied taxa as Poronileus. A
nileid, cf. Peraspis kujandensis displays typical nileid morphology, unlike the type species, Peraspis
lineolata, which might turn out to be an asaphid. Ampyx gongwusuensis sp. nov. of the Raphiophoridae is
the first record of the genus in the Zhuozishan area and reveals morphologic details that might be
employed to resolve Ampyx taxonomy in China. Morphologic differences between A. gongwusuensis and
Abulbaspis ordosensis might represent a case of sexual dimorphism.
Key words: Invertebrate paleontology, Trilobita, systematics, Klimoli Formation, Darriwilian,
Zhuozishan, Inner Mongolia
1 Introduction
The Zhuozishan area of Inner Mongolia is located in the
northwestern part of the Ordos Basin, which experienced
cratonic basin stage during the early Paleozoic (Yang et
al., 2015). There exposed are early Middle Ordovician
(Dapingian) to Late Ordovician (late Katian) sedimentary
strata, which yield abundant trilobites, graptolites, and
cephalopods (Chen et al., 1984; Zhou et al., 1989). Lu (in
Lu et al., 1976) reported three trilobite species in the area:
Bulbaspis
ordosensis,
Nileus
klimoliensis,
and
Paraptychopyge lashachungensis. This work presents a
systematic revision of the three species and reports cooccurring species based on a new collection comprising
about 130 specimens, many of which are well preserved
* Corresponding author. E-mail: dclee@chungbuk.ac.kr
and articulated.
The specimens were collected from an about 1-m thick
interval at the base of the section of the Klimoli Formation
exposed along a foothill of Zhuozishan located between
Laoshidan and Gongwusu counties (Fig. 1). One specimen
assigned to Abulaspis ordosensis (Lu in Lu et al., 1976)
was collected from a horizon 24 m above the interval. The
lithology of the sampling interval consists of alternating
layers of dark gray, medium-bedded, peloidal lime
mudstone and thin-bedded black shale.
2 Stratigraphy of Sampling Interval
Lu (in Lu et al., 1976) noted that Bulbaspis ordosensis
and Nileus klimoliensis occur in the upper part of the
Lower
Ordovician
Klimoli
Formation
and
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Fig. 1. Locality map of the section near Gongwusu county, Zhuozishan area near the border between Inner Mongolia and Ningxia,
China where the trilobite specimens were collected.
(a), Map of China showing the location of Fig. 1b map indicated by the black rectangle. (b), Map of sampled locality, Gongsuwu section; locality indicated by
a star, at GPS coordinate 39° 21’59”N, 106° 52’ 47”E; ‘G6’ is Jingzanggaosu expressway and ‘S314’ is Wushigaosu provincial road. (c), Field photograph
(facing south) of the sampled locality indicated by a white arrow. (d), Field photograph of the sampled interval indicated by a white bar.
Paraptychopyge lashachungensis occurs in ‘Lower
Ordovician strata’. In establishing a biostratigraphic
framework of the western Ordos region, Chen et al. (1984,
fig. 1) presented a stratigraphic column based on a
continuous Ordovician outcrop exposed at the eastern side
of Dongshan near Laoshidan County, which consists of
the Sandaokan, Zhuozishan, Klimoli, and Wulalike
formations in ascending order; the sampling locality (Fig.
1) of this study is considered to be a part of this outcrop.
Chen et al. (1984) recorded the occurrence of as many
as 16 trilobite genera from the uppermost 3-m thick
interval of the Zhuozishan Formation (‘interval 8’). The
assemblage was known to contain Ovalocephalus,
Sinoharpes (reassigned to Dubhglasina; see Zhou and
Zhen, 2008), Pseudosphaerexochus, and Pseudocalymene,
which have not been found in our collection, with the
occurrence of Nileus the only taxon comparable to the
present trilobite assemblage. Chen et al. (1984) also
recognized a total of seven intervals from the Klimoli
Formation and grouped them into three units; the upper
unit (‘interval 7’) is characterized by occurrences of
diverse graptolites and no trilobites; the middle unit
(‘interval(s) 3 to 6’) by those of diverse trilobites as well
as graptolites; the lower unit (‘interval(s) 1 and 2’) by
those of less diverse graptolites and trilobites. The
occurrence of Nileus klimoliensis and Paraptychopyge
lashachungensis was recorded throughout the intervals of
the middle unit; Bulbaspis sp. is listed only in interval 4 of
the middle unit. The occurrence of the first two species in
the present collection suggests that the sampling interval
belongs to the Klimoli Formation. N. klimoliensis is here
transferred to Symphysurus and P. lashachungensis to aff.
Mioptychopyge
(see
below).
However,
such
morphologically distinct trilobites as Hammatocnemis
(referred to Ovalocephalus; see Zhou and Zhen, 2008),
Remopleurides, and Shumardia from the middle unit have
not been found and only a single poorly preserved
graptolite specimen has been found in the present
collection. Thus, it cannot be determined to which interval
of Chen et al. (1984) the present sampling interval is
exactly correlated. Based on the graptolite occurrence, the
Klimoli Formation was considered to be of Llanvirn age
by Chen et al. (1984, table 2; see also Zhou et al., 1989)
and later was correlated to early–middle Darriwilian age
by Chen et al. (2010, fig. 11). Recently Wang et al. (2013)
carried out an integrated biostratigraphic study on the
formation based on conodonts and graptolites; their
sampling locality is about 14 km north of the locality of
the present study. They referred the limestone-dominated
lower unit yielding abundant conodonts to the Histiodella
kristinae Biozone of middle Darriwilian age (Wang et al.,
2013, fig. 16).
3 Composition of Assemblage
Of about 130 specimens, 47.0% is assigned to the
Nileidae, 45.5% to the Raphiophoridae, 6.7% to the
Asaphidae and 0.8% to the Telephinidae. Taking into
consideration that articulated specimens should contribute
more to the composition, the raphiophorids account for
53.7% of the assemblage, the nileids 41.0%, and asaphids
4.8% (Table 1). The following four species account for
82% of the fauna; Ampyx gongwusuensis sp. nov. (37%),
Symphysurus klimoliensis (Lu in Lu et al., 1976) (36%),
aff. Mioptychopyge lashachungensis (8% ), and cf.
Peraspis kujandensis (2% ). The composition may be
referable to the Nileid biofacies as defined by Zhou et al.
(1989) from the Zhuozishan area. The present assemblage
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Table 1 Trilobite faunal composition of the collection. Raw
number of articulated specimens is converted by
multiplying two in considering their contribution of
cranidium and pygidium. Isolated free cheeks, hypostomes
and thoracic segments are excluded from the calculation.
Number in parenthesis is based on the raw number
Articulated
Cephalothorax
Thoracopygidium
Cephalon
Cranidium
Pygidium
Subtotal
Proportion
Asaphidae
0
Nileidae
28 (14)
Raphiophoridae Telephinidae
80 (40)
0
0
3
14
0
0
0
2
7
9
4.8 %
(6.7 %)
20
1
15
10
77(63)
41.0 %
(47.0 %)
1
0
5
1
101(61)
53.7 %
(45.5 %)
0
0
1
0
1
0.5 %
(0.8 %)
contains less nileids (50% in Zhou et al., 1989) and much
more raphiophorids (20% in Zhou et al., 1989).
4 Systematic Paleontology
Terminology follows Whittington and Kelly (1997);
terminology of thoracic axial morphology of the Nileidae
follows Whittington (2000). Open nomenclature follows
Bengtson (1988). All the specimens are housed in the
Otog Comprehensive Geological Museum, Otog Banner,
Inner Mongolia, China (OCGM-Inv). Proportional values
of measurement are all in average, unless otherwise noted.
Abbreviations: sag. = sagittal, exsag. = exsagittal, tr. =
transverse
4.1 Taxon 1
Family Asaphidae Burmeister, 1843
Subfamily Nobiliasaphinae Balashova, 1971
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Genus Mioptychopyge Zhou et al., 1998
Type species.—Ptychopyge trinodosa Zhang, 1981,
from the Dawangou Formation, lower Llanvirn Series,
Kanlin, Kalpin, north-west Tarim, Xinjiang; by original
designation.
aff. Mioptychopyge lashachungensis (Lu in Lu et al.,
1976)
Figs. 2a, 3a–3m
Synonymy: 1976 Paraptychopyge lashachungensis Lu
in Lu et al., p. 65, pl. 11, figs. 1–3
Figured specimens: Two cranidia (OCGM-Inv. 1413,
1327), three pygidia (OCGM-Inv. 1417, 1513, 1438), free
cheek (OCGM-Inv. 1440) and hypostome (OCGM-Inv.
1525).
Description: The cranidium is wider than long; the
sagittal length is 72% of width along the posterior
cranidial margin. The frontal area is 47% of cranidial
width and 135% of glabellar width. Anterior branches of
the facial suture is divided into three distinct sections to
define a six-sided frontal area, the anterior end of middle
section being located at the level of the anterior 10% of
the exsagittal cranidial length and the posterior end at the
level of the anterior 38%. The anterior sections strongly
converge forward and meet at an acute angle, forming a
pointed anterior cranidial margin; the middle sections
moderately converge forward and are longest; posterior
sections diverge forward. The inflection from posterior to
middle sections is more angular than from middle to
anterior sections. The posterior branches of the facial
suture are moderately sinuous and the distal end is
strongly curved backward. The preglabellar furrow is
shallow and disappears sagittally. The frontal area is
relatively long (20% of cranidial length). The anterior
Fig. 2. Reconstruction of representative trilobite species from the Klimoli Formation; scale bars = 5 mm.
(a), aff. Mioptychopyge lashachungensis (Lu in Lu et al., 1976). (b), Symphysurus klimoliensis (Lu in Lu et al., 1976). (c), cf. Peraspis kujandensis
(Chugaeva, 1958). (d), Ampyx gongwusuensis sp. nov.
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Fig. 3. Photographs of specimens assigned to aff. Mioptychopyge: (a)–(m), aff. Mioptychopyge lashachungensis (Lu in Lu et al.,
1976); (n), aff. Mioptychopyge sp. indet.; scale bars = 5 mm.
(a–d), Cranidium, OCGM-Inv. 1413, (a) dorsal view, (b) anterior view, (c) posterior view, (d) lateral view. (e–f), Pygidium, OCGM-Inv. 1417, (e) dorsal
view, (f) lateral view. (g–h), Pygidium, OCGM-Inv. 1513, (g) posterior view, (h) dorsal view. (i), Hypostome, OCGM-Inv. 1525, ventral view. (j), Pygidium,
OCGM-Inv. 1438, dorsal view. (k), Cranidium, OCGM-Inv. 1327, dorsal view (note weakly developed baccula on the right side of palpebral area of fixigenae). (l–m), Free cheek, OCGM-Inv. 1440, (l) dorsal view (no the inner margin of doublure and fine terrace lines), (m) lateral view. (n), Pygidium, OCGMInv. 1307, dorsal view.
cranidial border is flat and occupies 58% of the
preglabellar area length. The border furrow is shallow,
widening slightly distally, and gently curved forward. The
preglabellar field is shorter (sag.) than the anterior
cranidial border. The axial furrows are moderately deep
and wide along the pre- and postocular areas of the
fixigena and shallower along the palpebral areas of the
fixigena; the furrows are strongly curved laterally to
delimit glabellar inflation and moderately curved inward
along the palpebral areas and parallel-sided along the
postocular areas. The glabella is pyriform, moderately
convex, and inflated laterally at mid-glabellar length; the
exsagittal length of the inflated part is 15% of glabellar
length; a shallow furrow is developed along the adaxial
margin of the inflated part; the inflation tends to be more
weakly developed in larger cranidia. The subcircular
depression is faintly developed along the glabellar crest
and located around mid-glabellar length; a weakly convex
fusiform lobe is present immediately in front of the
subcircular depression and along the glabellar crest; its
anterior end is located at the level of the mid-frontal area
length; two or three pairs of short furrows are impressed
adaxially from the axial furrows and located opposite
within the sagittal length of the fusiform lobe. The S1 is
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obliquely directed posteriorly and merges with the axial
furrows anteriorly at mid-way of the glabellar lateral
inflation, and they merge together posteriorly and
adaxially to define the posterior of the median node; the
L1 is subtriangular in outline. The median node is weakly
convex and located opposite the posterior end of the
palpebral lobes, which are apparently large (length
inferred to be 28% of cranidial length). The bacculae are
elongate (exsag.) and weakly raised along the posterior
two-thirds of the palpebral areas of the fixigena; baccular
furrows are faintly impressed. The occipital ring is
subrectangular and gently curved backward; the occipital
furrow is indistinct and deepens as a distinct elongate slit
at the distal end. The posterior area of the fixigena is
transverse and narrow (exsag.); a large protuberance is
present immediately adjacent to the occipital ring and in
front of the posterior cranidial border furrow. The
posterior cranidial border is narrow (exsag.) and strongly
raised as a narrow rim proximally and it progressively
widens distally; the border furrow with flat bottom slightly
widens distally. The frontal glabellar lobe and posterior
areas of the fixigenae are ornamented with fingerprint-like
fine terrace lines.
The librigenae have a broadly based, long genal spine.
The librigenal field gently slopes down. The lateral border
furrow is deep and wide, and becomes narrower and
shallower posteriorly into the genal spine tip. The eye
socle is narrow. The doublure is wide; its inner margin
extends along half of the librigenal field width. The
librigenal field and spine are ornamented with fingerprintlike terrace lines and the doublure has fine terrace lines
parallel to the librigenal margin.
The hypostome has a deeply notched posterior margin.
The middle body is subhexagonal in outline and
moderately convex. The lateral margin gently curves
outward; the lateral border furrow is shallow and deepens
posteriorly as a distinct subcircular apodemal pit; the
lateral border widens posteriorly and is ornamented by
terrace lines subparallel to the margin.
The pygidium is subsemicircular in outline; the length
is 68% of width across the posterolateral ends of the
articulating facets. The axial furrows are moderately deep
and straight; the axis gently tapers posteriorly with a
maximum width of 20% of pygidial width and the length
is 78% of pygidial length; up to 10 subrectangular axial
rings are defined by shallow inter-ring furrows which
disappear adaxially; axial furrows defining the terminal
piece shallow out posteriorly and adaxially. The
articulating facet is elongate (tr.), triangular in outline and
steeply downslopes anteriorly; there is a fulcrum at
halfway of the maximum pleural field width. The pleural
field is flat in the proximal half and then gently
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downslopes distally. Seven pairs of pleural furrows are
recognized; they are moderately deep and wide, and
become progressively shallower and narrower posteriorly;
the anteromost pair distally reaches the abaxial 20% of
half of the pygidial width; the interpleural furrows are
shallower, narrower and shorter than the pleural furrows.
The marginal border furrow is absent. The doublure is
moderately wide and becomes slightly wider posteriorly;
the inner margin reaches mid-width of the pleural field
and is located well inside the distal ends of the pleural
furrows; the posterior margin is deeply indented into the
anterior one-third of the sagittal length. The pygidial
surface is ornamented by relatively widely spaced,
fingerprint-like, fine terrace lines; the doublure is
ornamented with terrace lines which are subparallel to the
pygidial margin and spaced progressively wider toward
the margin.
Discussion and remarks: One cranidium and two
pygidia of Paraptychopyge lashachungensis were
illustrated by Lu et al. (1976, pl. 11, figs. 1–3). The
holotype cranidium differs from the present cranidia in
being larger and having a shorter (sag.) frontal area and
more weakly developed glabellar inflation at the midglabellar length. These differences are interpreted as
intraspecific and/or ontogenetic variation (compare with
Figs. 3a, k). The two paratype pygidia are
indistinguishable from those of the present collection.
Lu (in Lu et al., 1976) assigned this species to
Paraptychopyge because the following two cranidial
features were thought to be well accommodated within the
generic diagnosis defined by Balashova (1964, p. 11):
sagittal length of the frontal area is one-sixth of cranidial
length and exsagittal length of the postocular area of the
fixigenae is equal to or slightly greater than exsagittal
length of the palpebral lobes. As the frontal area of the
present cranidia is one-quarter to one-fifth of the cranidial
length, the shorter frontal area of the holotype cranidium is
interpreted as an ontogenetic feature. In the holotype
cranidium, the size and shape of the palpebral lobes cannot
be accurately determined due to poor preservation; it
seems that a curved furrow on the left side was interpreted
as an outline of the palpebral lobe by Lu (in Lu et al.,
1976). With the course of the anterior and posterior
branches of the facial suture, the palpebral lobes of the
present cranidia, although incomplete, appear to be much
longer than the postocular area of the fixigenae (Fig. 2a).
The two features employed by Lu are thus not considered
taxonomically valuable for the assignment of this species
to Paraptychopyge. Of Paraptychopyge species from
Baltoscandia, the Zhuozishan species is most similar to P.
plautini in sharing a hexagonal frontal area and seven
pairs of relatively long pygidial pleural furrows
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(Balashova, 1964, pl. 3, figs. 5–9). However, P. plautini is
readily distinguished by having a shorter frontal area
apparently with no preglabellar field, smaller palpebral
lobes, more weakly impressed and less obliquely directed
S1, more distinctly developed bacculae, a longer (exsag.)
postocular area of fixigenae defined by weakly sinuous
posterior branches of the facial suture, a wider and longer
pygidial axis, and convex distal ends of the pygidial
pleural ribs. It is concluded that the Zhuozishan species is
not a member of Paraptychopyge.
The Zhuozishan species displays a combination of
characters of Mioptychopyge Zhou, Dean, Yuan and Zhou,
1998, Ningkianites Lu, 1975, Opsimasaphus Kielan, 1959
and Zhenganites Yin in Yin and Lee, 1978. Turvey (2007)
transferred these Chinese genera to the subfamily
Nobiliasaphinae Balashova, 1971 after comprehensively
reviewing many effaced asaphids from South China in
comparison with those from Baltoscandia; he concluded
that the Chinese nobiliasaphines share hypostomal and
cranidial morphologies distinguishable from those of the
Baltoscandian asaphids (see Turvey, 2007, text-fig. 7).
The Zhuozishan cranidia have a pear-shaped glabella as
do the nobiliasaphines. The glabella inflates at midglabellar length and the inflation reduces with growth
(compare Fig. 3a, 3k, and Lu et al., 1976, pl. 11, fig. 1).
An identical inflation is well developed in
Dolerobasilicus, a Korean nobiliasapine genus (Lee and
Choi, 1992, pl. 1, figs. 2–3) which also reduces
ontogenetically. Bacculae are recognized in the
Zhuozishan cranidia and some of the nobiliasaphine
genera such as Zhenganites and Mioptychopyge (e.g.,
Zhou et al., 1998, pl. 2, fig. 6, pl. 3, fig. 4); in the former
genus, the large protuberance on the fixigena behind the
eyes is interpreted as a baccula; the Zhuozishan species
have both elongated (exsag.) bacculae and a protuberance
behind it (Fig. 3a). Ontogenetic information is required to
assess identity of these cephalic structures and their
taxonomic value, as claimed by Lee and Choi (1999).
An axial fusiform lobe delineated by weakly impressed
furrows is present along the glabellar crest of the
Zhuozishan species (Figs. 2a, 3a). An identical lobe is
found in Mioptychopyge trinodosa (e.g., Zhou et al., 1998,
pl. 3, fig. 4), which is described as ‘an axially extended,
spear-shaped ridge.’ The lobe or ridge is apparently absent
in other Mioptychopyge species (e.g., M. suni, Turvey,
2007, pl. 3, fig. 8), whereas it is observed in other
nobiliasaphines (e.g., Nobiliasaphus nobilis, Přibyl and
Vaněk, 1965, pl. 2, fig. 7) and even in nonnobiliasasphines (e.g., Pseudobasiliella kuckersiana,
Balashova, 1971, pl. 2, fig. 7). The lobe is of little
taxonomic use for generic assignment of the Zhuozishan
species.
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The most noticeable feature of the Zhuozishan cranidia
is that the anterior branches of the facial suture are
distinctly divided into three sections to form a hexagonal
outline (Figs. 3a, 3k). A similar hexagonal outline is
observed in the three Chinese nobiliasaphine genera,
except for Opsimasaphus, which displays laterally convex
anterior branches of the facial suture (e.g., O.
pseudodawanicus, Turvey, 2007, fig. 13). The relative
length and direction of the middle section display
noticeable variations. The Zhuozishan species is most
similar to Zhenganites xinjiangensis (e.g., Zhou et al.,
1998, pl. pl. 2, fig. 6) in sharing forward-converging
middle sections; Zhenganites guizhouensis, the type
species, however, shows laterally convex anterior
branches without noticeable inflections (Yin and Lee,
1978, pl. 174, figs. 3–5). The Zhuozishan species differs
in having the middle sections longer than the anterior
sections, posterior sections longer than middle sections,
and less strongly forward-converging anterior sections.
This character varies too much among species of each
genus to be used to attribute the Zhuozishan species to a
specific genus. The variations observed in Mioptychopyge
are as follows: in M. trinodosa, the middle sections are
parallel-sided, as long as the anterior sections, and longer
than the posterior sections; in M. suni, the middle sections
diverge forward and are shorter than the anterior sections
but longer than the posterior sections; and in M.
tatsaotzensis, the middle sections converge forward and
are shorter than the anterior and posterior sections
(compare Zhou et al., 1998, pl. 3, fig. 4; Turvey, 2007, pl.
3, fig. 8; Lu et al., 1976, pl. 10, fig. 3). Ningkianites
insculpta, the type species, displays the distinct hexagonal
outline but with slightly forward-diverging middle
sections and longer anterior sections (e.g., Turvey, 2007,
pl. 5, fig. 2). However, Ningkianites fenhsiangensis has a
laterally convex outline as in Z. guizhouensis (Yi, 1957,
pl. 2, figs. 2a–2b); it is questionable that the cranidium of
N. fenhsiangensis truly belongs to Ningkianites because it
has a very short (sag.) preglabellar area and a narrow (tr.)
frontal area.
In the Zhuozishan cranidia, the frontal area width is
about half of the posterior cranidial margin width as in
Zhenganites and Ningkianites, whereas it is much wider in
Mioptychopyge and Opsimasaphus (character 1 in Table
2). The Zhuozishan cranidia are least consistent with
Zhenganites in terms of preglabellar area length and
palpebral lobe size (characters 2 and 3 in Table 2). The
Zhuozishan cranidia are least consistent with those of
Mioptychopyge in terms of cranidial length to width ratio
(character 4 in Table 2).
The median node of the Zhuozishan species is located
at the level of the posterior ends of palpebral lobes as in
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Table 2 Quantitative data for comparison of the Chinese nobiliasaphine genera. Characters are described in the diagram
below
Character
aff. Mioptychopyge lashachungensis
Mioptychopyge
Mioptychopyge trinodosa
Mioptychopyge suni
Mioptychopyge tatsaotzensis
Zhenganites
Zhenganites xinjiangensis
Zhenganites guizhouensis
Opsimasaphus pseudodawanicus
Ningkianites insculpta
1
a/e
47%
71%
70%
71%
48%
48%
68%
51%
Mioptychopyge (e.g., Zhou et al., 1998, pl. 3, fig. 4). It is
located anterior to the posterior ends in Zhenganites (e.g.,
Z. guizhouensis, Yin and Lee, 1978, pl. 174, fig. 4; Z.
xinjiangensis, Zhou et al., 1998, pl. 2, fig. 10), whereas it
is posterior to the ends in Ningkianites and Opsimasaphus
(e.g., N. insculpta, Lu 1975, pl. 7, fig. 4; O.
pseudodawanicus, Turvey, 2007, pl. 3, fig. 13 and Lu,
1975, pl. 5, fig. 25). The posterior branches of the facial
suture of the Zhuozishan species are moderately sinuous,
whereas those in Zhenganites and Mioptychopyge are
strongly sinuous (e.g., Zhou et al., 1998, pl. 2, fig. 6, pl. 3,
fig. 4) and those of Opsimasaphus and Ningkianites are
weakly sinuous (e.g., Turvey, 2007, pl. 3, fig. 13, pl. 5,
fig. 2). The subrectangular occipital ring of the
Zhuozishan species is reminiscent of M. tatsaotzensis (Lu
et al., 1976, pl. 10, fig. 3) and O. pseudodawanicus (e.g.,
Turvey, 2007, pl. 4, fig. 3). The ring is subtrapezoidal in
Zhenganites, Ningkianites and M. trinodosa (e.g., Zhou et
al., 1998, pl. 2, fig. 6; Turvey, 2007, pl. 5, fig. 2; Zhou et
al., 1998, pl. 3, fig. 4), whereas it is strongly convex
posteriorly in M. suni (e.g., Turvey, 2007, pl. 3, fig. 8).
The nobiliasaphine pygidia are generally wider than
long and the Zhuozishan pygidia show an intermediate
value in terms of the length to width ratio (character 5 in
Table 2). The Zhuozishan pygidia are characterized by a
narrowest axis as in those of M. tatsaotzensis (character 6
in Table 2). The doublure of the Zhuozishan pygidia is
Cranidium
2
3
b/d
c/d
22%
29%
24%
30%
27%
30%
23%
28%
23%
32%
15%
45%
13%
45%
17%
44%
25%
24%
21%
29%
91%
72%
72%
5
g/f
60%
67%
73%
63%
64%
52%
52%
Pygidium
6
h/f
20%
27%
33%
26%
21%
25%
25%
70%
75%
55%
54%
26%
26%
4
d/e
72%
94%
97%
7
j/i
29%
41%
28%
46%
49%
49%
26%
narrower (Fig. 3j), as in O. pseudodawanicus and M.
trinodosa (character 7 in Table 2); unlike the other two
species, the doublure in M. trinodosa becomes strongly
wider posteriorly; Z. xinjiangensis has the widest
doublure, accounting for approximately half of the
pygidial width.
The Zhuozishan pygidia are readily distinguished from
those of Ningkianites and Zhenganites; Ningkianites is
characterized by its distinctly impressed marginal border
furrow (e.g., N. insculpta, Turvey, 2007, pl. 5, fig. 4) and
Zhenganites by its convex distal ends of the pleural ribs
(e.g., Z. xinjiangensis, Zhou et al., 1998, pl. 2, figs. 7, 12).
The subsemicircular pygidial outline is reminiscent of O.
pseudodawanicus (e.g., Lu, 1975, pl. 6, figs. 7–8) and M.
tatsaotzensis; the length and depth of the pleural furrows
are also similar in these species; M. tatsaotzensis and the
Zhuozishan species further share a longer postaxial region.
Turvey (2007) claimed that hypostomal characters are
the most informative in classifying effaced asaphids and
employed
them
to
differentiate
the
Chinese
nobiliasaphines from the Baltoscandinian asaphids (textfig. 7). An incomplete hypostome in ventral view (Fig. 3i)
displays a subhexagonal middle body, a deep and circular
apodemal pit at the posterior end of the lateral border
furrows and a deeply, widely-notched posterior margin. Of
the Chinese nobiliasaphine genera under comparison, the
hypostome is recorded for M. suni (Li et al., 1975, pl. 18,
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fig. 4), O. pseudodawanicus (Turvey, 2007, pl. 4, fig. 9)
and Z. xinjiangensis (Zhou et al., 1998, pl. 2, fig. 8). That
of M. suni in ventral view is readily differentiated by its
wider and rounded middle body, narrower lateral border
and pair of large maculae delimited by a middle furrow
anteriorly and a posterolateral border furrow posteriorly;
both furrows are of approximately equal depth. The
partially preserved hypostome of O. pseudodawanicus
seen in dorsal view is distinguished by a diamond-shaped
middle body; in other words, the anterior half of the
middle body strongly narrows forward. The hypostome of
Z. xinjiangensis in ventral view shares the subhexagonal
middle body but has a slightly wider lateral border. In Z.
xinjiangensis, a pair of smaller maculae are located
immediately adaxial to the deep posterior end of the lateral
border furrows and surrounded by shallow middle and
posterior border furrows. This clearly contrasts with the
condition in M. suni where middle and postero-lateral
border furrows of equal depth delimit the large maculae. It
is thought that the Zhuozishan hypostome, although
maculae are poorly preserved, has a similar configuration
to that of Z. xinjiangensis.
It is certain that the Zhuozishan species is more closely
related to Mioptychopyge and Zhenganites than
Ningkianites and Opsimasaphus. Although the species
appears to bear more resemblance to Mioptychopyge, lack
of accurate information on hypostomes and palpebral
lobes prevents us from ascribing it with confidence to the
genus. Since the hexagonal outline of the anterior
branches of facial suture, in combination with other
characters such as subsemicircular pygidium, are
considered to be unique among the nobiliasaphine genera,
it is possible that the species might belong to a new genus.
4.2 Taxon 2
aff. Mioptychopyge sp. indet.
Fig. 3n
Figured specimens: Pygidium (OCGM-Inv. 1307).
Remarks: A single incomplete pygidium differs from
the pygidia of aff. Mioptychopyge lashachungensis (see
above) in having a sagittally longer outline, up to 10 pairs
of wider pleural and interpleural furrows, up to 13 axial
rings, and a relatively straight anterior margin without
curving posteriorly at the fulcrum.
4.3 Taxon 3
Family Nileidae Angelin, 1854
Genus Symphysurus Goldfuss, 1843
Type species: Asaphus palpebrosus Dalman, 1827,
from Husbyfjöl in Västergötland, Sweden; subsequently
designated by Barrande (1852).
Symphysurus klimoliensis (Lu in Lu et al., 1976)
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Figs. 2b, 4a–4t
Synonymy: 1976 Nileus klimoliensis Lu in Lu et al., p.
66, pl. 12. fig. 3.
Holotype: Exoskeleton lacking free cheeks (23927, Lu
in Lu et al., 1976, pl. 12, fig. 3) housed in Nanjing
Institute of Geology and Palaeontology.
Type horizon and locality: Middle Ordovician
Klimoli Formation, Lashizhong, Zhuozishan area, Inner
Mongolia, China.
Figured specimens: Three exoskeletons (OCGM-Inv.
1475, 1401, 1301), thoraco-pygidium (OCGM-Inv. 1397),
three cranidia (OCGM-Inv. 1473, 1515, 1412), two
pygidia (OCGM-Inv. 1432, 1306), hypostome (OCGMInv. 1441), and thoracic segments (OCGM-Inv. 1484).
Diagnosis: Species with moderately convex
exoskeleton; cephalic axial furrows shallow and narrow;
thorax of eight segments with elongated (tr.) goggleshaped lobe defined by shallow furrow in axial rings.
Pygidium subsemicircular without marginal border
furrow; doublure narrow (about one-third of pygidial
width). Dorsal surface covered with fingerprint-like, fine
terrace lines.
Description: The exoskeleton is elliptical in outline
and 60% wider than long. The cephalon is semi-circular in
outline and about one-third of exoskeletal length. The
cranidium is subtrapezoidal in outline with a rounded
anterior margin; the sagittal length is 90% of width along
the posterior cranidial margin. There are no furrows in the
frontal area on the external surface; the narrow flat
anterior border is recognized in internal mold and
delimited by a shallow furrow that disappears sagittally.
The anterior branches of the facial suture diverge forward
and then strongly turn adaxially along the cranidial
margin; posterior branches are straight and run obliquely
at about 40° from the exsagittal line. The axial furrows are
shallow and not impressed in the frontal area and are
impressed away from the facial suture posterior to the
frontral area; they are slightly curved adaxially around the
level of the posterior ends of the palpebral lobes and then
diverge slightly posteriorly. The glabella rapidly
downslopes forward into the frontal area and is otherwise
moderately convex; the glabellar crest is weakly carinated.
Five pairs of large muscle impression areas are weakly
impressed; the anteriormost pair is smallest and closest to
each other; a small median node (visible only on the
internal mold) is located between the anterior and
posterior ends of the palpebral lobes (at the level of the
posterior 31% of cranidial length). The occipital ring is
elongate (tr.) spindle-shaped and defined by a weakly
impressed occipital furrow. The palpebral lobe is
semicircular in outline and 38% of cranidial length; the
mid-palpebral point is located at the level of the anterior
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Fig. 4. Photographs of specimens of Symphysurus klimoliensis (Lu in Lu et al., 1976); scale bars = 5 mm.
(a–c), Exoskeleton with displaced free cheeks, OCGM-Inv. 1475, (a) dorsal view, (b) lateral view, (c) magnified ventral view of hypostome (note the
alternation of wider and narrower terrace lines). (d–f), Cranidium, OCGM-Inv. 1473, (d) dorsal view, (e) lateral view (note the flat anterior border
defined by shallow furrow), (f) anterior view. (g), Exoskeleton lacking free cheeks, OCGM-Inv. 1401, dorsal view. (h–j), Pygidium, OCGM-Inv. 1432,
(h) dorsal view (note the inner margin of doulbure), (i) posterior view, (j) anterior view. (k), Hypostome, OCGM-Inv. 1441, ventral view. (l),
Cranidium, dorsal view, OCGM-Inv. 1515. (m–n), Cranidium, OCGM-Inv. 1412, (m) dorsal view, (n) magnified view of frontal area showing terrace
lines. (o–p), Pygidium (latex cast), OCGM-Inv. 1306, (o) posterior view, (p) dorsal view. (q–r), Incomplete exoskeleton, OCGM-Inv. 1301, (q) dorsal
view, (r) lateral view. (s), Magnified view of pygidium of thoraco-pygidium, OCGM-Inv. 1397, dorsal view (note the presence of fingerprint-like
terrace lines and the absence on axial region). (t), Thoracic segments, OCGM-Inv. 1484, ventral view (note the presence of “ventral ridge” and “oval
area” of Whittington (2000)).
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60% of cranidial length; the anterior end is located more
adaxially than the posterior end. The cranidial surface is
ornamented with fingerprint-like, fine terrace lines; those
in the frontal area are more widely spaced and subparallel
to the anterior margin but are much less distinct in the
internal mold.
The librigenal fields slope down steeply; border
burrows are not impressed. The postero-lateral corner is
rounded. The eyes are large. The cephalic doublure is
moderately wide, and ornamented with fine terrace lines
parallel to the cephalic margin.
The hypostome is subquadrate in outline. The anterior
wing is small and triangular. The anterior margin is almost
straight, the lateral margin is strongly convex laterally and
the posterior margin is gently tripartite. The middle body
is rounded; the anterior lobe is twice as long (sag.) as the
posterior lobe; the lateral border furrow deepens and
widens posteriorly with the deepest pit at the posterior
end. The ventral surface is covered with alternating thicker
and thinner fingerprint-like, round-crested terrace ridges;
the dorsal surface is covered with less strongly raised
terrace ridges.
The thorax has eight segments and is one-third of
carapace length. The axial furrows are shallow and
parallel-sided; the axial region is moderately convex and
43% of thoracic width; the axial rings are elongate (tr.)
trapezoidal; an elongate (tr.) goggle-shaped lobe is present
in each ring, which is posteriorly and laterally delineated
by a shallow furrow (the lobe corresponds to the ‘oval
area’ and the furrow to the ‘ventral ridge’ of Whittington
(2000)); anterior and posterior ventral ridges are present in
each axial ring; the anteromost is much more prominent;
anterior and posterior ridges are overlapped and expressed
as a shallow furrow on the external surface. The pleurae
are horizontal and then slope down from the fulcral line;
the distal ends of the pleurae are gently curved posteriorly.
Pleural furrows are shallow and wide, diagonal, and
disappear halfway down pleural width; the anterior pleural
band is strongly raised as an elongate triangular ridge and
the posterior pleural band is moderately convex. The
fulcrum of the first pleura is located very close to the axial
furrows; fulcral lines gently diverge posteriorly from the
first to fourth pleurae and are parallel-sided from the
fourth to eighth pleurae; the width (tr.) of the articulating
facet changes accordingly; fulcral processes are small. The
thoracic surface is ornamented with weakly raised,
fingerprint-like, fine terrace lines subparallel to the
transverse lines. The doublure is almost half the pleural
width and ornamented with more widely spaced terrace
lines subparallel to the lateral margin--.
The pygidium is subsemicircular in outline with a
gently convex anterior margin with a length 57% of width.
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The axial furrows are shallow and slightly curved
adaxially to delineate a funnel-shaped axis; seven axial
rings and a terminal piece are recognized; inter-ring
furrows are faintly impressed; up to six pairs of rounded,
weakly impressed muscle impression areas are recognized.
The pleural field gently slopes down; the pleural and
interpleural furrows are faintly impressed, except for the
anteriormost pair; up to three pleural ribs are recognized;
the fulcrum is the same as in thoracic pleurae. The
doublure is moderately wide (about one-third of pygidial
width and length) and becomes slightly wider posteriorly;
it is moderately indented into the anterior quarter of its
sagittal length. Fine, fingerprint-like terrace lines are
present on the external surface of the pleural region, but
absent on the axial region; the doublure is ornamented
with more widely spaced terrace lines parallel to the
pygidial margin.
Remarks: Lu in Lu et al. (1976) erected Nileus
klimoliensis based on a single exoskeleton lacking free
cheeks (pl. 12, fig. 3). Several articulated, well-preserved
exoskeletons in the present collection provide
morphologic details for systematic revision of this
Zhuozishan nileid. From Nileus armadillo (Dalman, 1827)
the type species (e.g., Schrank, 1972, pl. 6, figs. 1–3, 5–6;
Nielsen, 1995, figs. 147–151), the Zhuozishan species
differs in having a longer (sag.) frontal area, a longer
(exsag.) posterior area of the fixigenae, and much smaller
palpebral lobes. The axial furrows of the Zhuozishan
species are distinctly impressed away from the facial
suture, whereas in N. armadillo the furrows are only
recognized along the palpebral areas of the fixigenae and
meet the anterior and posterior ends of the palpebral lobes.
A subsemicircular pygidium of the Zhuozishan species
lacks the marginal border furrow, whereas in N. armadillo,
the pygidium is fusiform in outline with a more strongly
convex anterior margin and a distinct border furrow. The
Zhuozishan species has a narrower doublure with an inner
margin subparallel to the pygidial margin, whereas in N.
armadillo, the doublure is much wider and the inner
margin is convex adaxially.
In reviewing the concept of the family Nileidae,
Whittington (2003) diagnosed Nileus Dalman, 1827, the
genotype, as having a glabellar organ expressed as a
median node in the internal mold, ventral ridges in the
thoracic axial region as muscle insertion areas, oval
depressed areas between the ridges on the visceral surface
(see also Whittington, 2000), and nonfulcrate thoracic
pleurae; the absence of such features corresponding to the
ridges and oval areas on the external surface is also
considered as diagnostic in Nileus. A similarily positioned
median node is found in the internal molds of the
Zhuozishan crandia (e.g., Figs. 4d, 4m, 4q). The thoracic
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axial features are also observed on the visceral surface
(Fig. 4t), which are, however, observed as a goggle-shaped
lobe, which corresponds to the oval areas that are fused
into a single lobe, defined by a shallow furrow, which
corresponds to the ventral ridge, on the external surface as
well as the internal mold (Figs. 4a–4b, 4q, 4t); the lobes
and furrows are more distinct in the internal molds. The
thoracic pleurae of the Zhuozishan species are definitely
fulcrate because the horizontal inner pleural portion is
present adaxial to the fulcral line (Figs. 4a, 4q).
Most cranidial features in the diagnosis of Nileus as
defined by Fortey (1975, p. 40) are found in the
Zhuozishan cranidia; unlike Nileus, however, the cranidial
length in the Zhuozishan species is always longer than the
transverse width between the palpebral lobes (length 89%
of transverse width). In reviewing Elongatanileus Ji, 1986
in comparison with Nileus, Poronileus and Peraspis,
Fortey (1997) noted that Nileus has the maximum
cranidial width at the palpebral lobes; it is noted that the
Zhuozishan cranidia are widest between palpebral lobes
(113% of cranidial length).
The pygidial doublure allows us to differentiate the
Zhuozishan species clearly from Nileus (see Fortey, 1975,
fig. 4). Because it has a relatively narrow doublure with an
inner margin almost parallel to the pygidial margin, as in
Symphysurus Goldfuss, 1843 (compare Figs. 4a, 4h with
Fortey, 1975, fig. 4E), the Zhuozisan species is assignable
to that genus. Also the nature of the pygidial doublure
distinguishes the Zhuozishan species from two welldefined Darriwilian (late Arenig to Llanvirn) Nileus
species from China, N. walcotti Endo, 1932 from South
China and N. sericeus Turvey, 2007 from Xinjiang; N.
walcotti has a fusiform pygidium with a wide doublure
(e.g., Turvey, 2007, pl. 10, figs. 3, 6) and N. sericeus has a
subsemicircular but sagittally shorter pygidium with a
wide doublure (e.g., Zhou et al., 1998, pl. 5, figs. 8, 11).
Given that the thoracic pleural details from the
articulated specimen and/or pygidial doublure are not
known, some Nileus species are quite comparable with the
Zhuozishan species. For example, the Zhuozishan species
is comparable with N. glazialis costatus (e.g., Fortey,
1975, pl. 10, figs. 1, 5) in the cranidial and pygidial
morphologies and with N. orbiculatoides svalbardensis
(e.g., Fortey, 1975, pl. 11, fig. 3) in hypostomal
morphology.
In cranidial and pygidial aspects, the Zhuozishan nileid
is also comparable to Poronileus Fortey, 1975 and
Symphysurus but it is more similar to the latter. Poronileus
was diagnosed cranidially by Fortey (1975, p. 51) as being
longer than wide, of low convexity, pitted and having
axial furrows connecting anterior and posterior ends of the
palpebral lobes. From Poronileus, the Zhuozishan species
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1965
differs in having axial furrows incised away from the
posterior end of the palpebral lobes and the surface
covered only with fingerprint-like, fine terrace lines
(compare Poronileus fistulosus, the type species, e.g.,
Fortey, 1975, pl. 13, fig. 1, pl. 41, fig. 3). However, some
Poronileus species display a cranidial morphology that is
found to deviate from the diagnosis but be rather similar to
the Zhuozishan crandia (e.g., P. jugatus, Fortey, 1975, pl.
17, fig. 1). The pygidial morphology also allows us to
differentiate the Zhuozishan species more convincingly
from Poronileus; the Zhuozishan pygidia have a wider
than long outline (length 58% of width and 67% in
Poronileus), much narrower doublure, and no marginal
border furrow (see also Fortey, 1975, fig. 4).
The diagnosis of Symphysurus (Fortey, 1986, p. 256)
describes its cranidium as having well-defined axial
furrows, parallel-sided or slightly forward-expanding
glabella, and terrace lines on the cranidial surface. The
cranidial morphology of the Zhuozishan species is
consistent with that diagnosis. From Symphysurus
palpebrosus (Fortey, 1986, fig. 1), the Zhuozishan
cranidia differ in having a less convex cranidium, much
shallower axial furrows, much finer terrace lines, and a
slightly more posteriorly located median node. The
pygidium of Symphysurus is diagnosed as having a
subsemicircular outline, a long and dorsal weakly defined
axis, and a doublure subparallel to the margin, and lacking
a distinct border (Fortey, 1986, p. 256). The Zhuozishan
pygidia only differ from those of S. palpebrosus in having
a funnel-shaped axis and terrace lines on the surface (e.g.,
Fig. 4h); S. palpebrosus is described as having terrace
lines only on the cranidial surface and thoracic axial rings.
Of described Symphysurus species, the Zhuozishan
species is most similar to Symphusurus arcticus from
Spitbergen (Fortey, 1975, pl. 21, figs. 1–16). It differs in
having eight (seven in S. arcticus) thoracic segments, a
longer (sag.) frontal area, and a narrower pygidial
doublure. We thus conclude that the Zhuozishan species
should be transferred into Symphysurus.
Two Symphysurus species from Shaanxi, S. carinatus
and S. subquadratus were recorded by Lu (1975, pl. 24,
figs. 4–7, pl. 25, figs. 1–5). These two species are readily
distinguished by having deep axial furrows and a fairly
convex glabella and thoracic axial region, which are more
comparable to those of S. palpebrosus (Fortey, 1986, fig.
1).
Chang and Fan (1960) erected five new species of
Symphysurus from Gansu and Qinghai based on
inadequate material. Fortey (1986) suggested that all these
might be transferred into Poronileus because of their
smaller palpebral lobes and medially constricted glabella.
The exsagittal length of the palpebral lobe accounts for
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42% of cranidial length in the Spitsbergen Poronileus
species described by Fortey (1975), whereas it is about
40% in well-defined Symphysurus species such as S.
palpebrosus (Fortey, 1986), S. angustatus (Ebbestad,
1999) and S. arcticus (Fortey, 1975); it is 39% in S.
klimoliensis. The glabellar constriction occurs along the
palpebral area of the fixigenae in the Chinese species
(Chang and Fan, 1960, pl. 1, fig. 1, pl. 2, figs. 3–5, 7–11,
19, 21, text-figs. 5–10; Zhou et al., 1982, pl. 66, fig. 10)
and the intensity of the constriction varies among them.
The glabella is similarily constricted in S. arcticus (e.g.,
Fortey, 1975, pl. 21, fig. 1)- and S. klimoliensis (e.g., Fig.
4g). These two features are not so differentiated as to
allow us to transfer these species erected by Chang and
Fan (1960) into Poronileus. It is apparent that the
associated pygidia (Chang and Fan, 1960, pl. 2, figs. 7–8,
19) are wider than long and have a fairly wide doublure,
which is reminiscent of Nileus. Zhou in Zhou et al. (1982)
erected S. longmendongensis from Shaanxi based on a
single cranidium (pl. 66, fig. 12). The cranidium is most
similar to S. klimoliensis (compare with Fig. 4d) among
the above-mentioned Chinese species, but has its axial
furrows connecting the anterior and posterior ends of the
palpebral lobes.
Zhou in Zhou et al. (1982) erected two Poronileus
species from Ningxia, P. angustus (pl. 66, figs. 13–14)
and P. miboshanensis (pl. 67, figs. 1–4). Although it is
difficult to assess these species due to poor preservation,
the cranidia of both species appear to be comparable to
those of S. klimoliensis (compare Fig. 4l) and cf. Peraspis
kujandensis (see below). An associated pygidium (pl. 66,
fig. 14) is more similar to that of Poronileus (pl. 66, fig.
14) and the other (pl. 67, fig. 3) is not of Poronileus or
Symphysurus type; the associated hypostome (pl. 67, fig.
4) is similar to that of Poronileus (e.g., Fortey, 1975, pl.
13, fig. 8). It seems that the Ningxia material represents a
mixture of more taxa than described by Zhou et al. (1982).
Accurate taxonomic assessment of all these Chinese
species awaits detailed morphologic information based on
more and better-preserved specimens that reveal the nature
of the pygidial doublure in particular, which will
eventually confirm whether or not Poronileus truly occurs
in China.
4.4 Taxon 4
Nileid gen. et sp. indet.
Fig. 5j–k
Figured specimens: Incomplete cephalon (OCGM-Inv.
1540).
Remarks: The incomplete cephalon is characterized by
smaller palpebral lobes (26% of cranidial length), a longer
(exsag.) postocular area of the fixigenae, with the mid-
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palpebral point at mid-glabellar length. Since other
exoskeletal information, in particular the correctly
associated pygidium (where is this specimen???) , is not
available, the generic and specific attribution (NB. the
species is the key taxon) cannot be determined.
4.5 Taxon 5
Genus Peraspis Whittington, 1965
Type species: Niobe lineolata Raymond, 1925 from
Table Head Formation, Aguathuna, Port au Port peninsula,
western Newfoundland, Canada; subsequently designated
by Whittington (1965).
Remarks: In erecting Peraspis, Whittington (1965)
assigned it to the Nileidae because it lacks the median
suture. Later, Whittington (2003) excluded it from the
family by claiming instead its asaphid affinity because the
type species, Peraspis lineolata Whittington, 1965 shows
the asaphid condition in regard to the glabellar tubercle
and thoracic axial features. The tubercle is located much
more posteriorly, near the occipital furrow, and is
observed on the external surface as well as the internal
mold (Whittington, 1965, pl. 34, fig. 9). The thoracic axial
rings are equipped with an articulating furrow and half
ring (e.g., Whittington, 1965, pl. 34, figs. 1, 9) instead of
having nileid thoracic axial features (Whittington, 2000
for detailed discussion on the latter). The glabellar
turbercle in some species later assigned to Peraspis is of
nileid-type in that it is more anteriorly located and
observed only in the internal mold (e.g., Ross, 1970, pl.
15, fig. 4 for Peraspis erugata; Dean, 1973, pl. 4, fig. 5 for
Peraspis yukonensis; Fortey, 1975, pl. 19, fig. 1, pl. 20,
figs. 1, 3 for Peraspis erugata and Peraspis omega); the
nature of the tubercle cannot be determined in Peraspis
kolouros (Norford and Ross, 1978, fig. 6). The presence of
a nileid or asaphid-type thoracic axial configuration
cannot be confirmed for these species, as noted by
Whittington (2003). These later-described Peraspis
species share with the type species the presence of genal
spines and more deeply impressed pygidial pleural
furrows, which differentiates Peraspis from other nileids
(Fortey and Chatterton, 1988). However, some features are
observed in these species that are significantly different
from P. lineolata, which lead us to question whether
Peraspis is a natural group: the preglabellar area of these
species has a very narrow preglabellar or anterior cranidial
border furrow (e.g., P. erugata and P. kolouros) or
apparently lacks the furrow (e.g., P. omega), whereas P.
lineolata has a distinct furrow delimiting the glabellar
front; the thorax is parallel-sided in these species, whereas
it widens posteriorly in P. lineolata; and the posterior end
of the pygidial axis in these species falls short of the
marginal border furrow, whereas it reaches the furrow in
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Fig. 5. Photographs of specimens: (a–i), (l), cf. Peraspis kujandensis (Chugaeva, 1958); (j–k), Nileid gen. indet.; (m), Telephina sp.
indet.; scale bars = 5 mm.
(a–d), Exoskeleton lacking librigenae, OCGM-Inv. 1465, (a) dorsal view, (b) lateral view, (c) anterior view, (d) posterior view. (e), Cranidium, OCGM-Inv.
1314, dorsal view. (f–h), Cranidium, OCGM-Inv. 1478, (f) dorsal view, (g) lateral view, (h) anterior view. (i), Thoraco-pygidium OCGM-Inv. 1322, lateral
view. (j–k), Incomplete cephalon, OCGM-Inv. 1540, (j) lateral view, (k) dorsal view. (l), Thoraco-pygidium, OCGM-Inv. 1370, dorsal view (note the inner
margin of doublure). (m), Cranidium, OCGM-Inv. 1404, dorsal view.
P. lineolata. These features of P. lineolata are more
asaphid-like. Hypostomal morphology may enable us to
resolve this problem. Nevertheless, Whittington (2003, p.
642) questioned the association of nileid-type hypostomes
with P. lineolata (Whittington, 1965, pl. 35, figs. 6, 8).
The association of the nileid-type hypostome is confirmed
in P. yukonensis (Dean, 1973, pl. 4, figs. 1, 3), P. erugata
(Fortey, 1975, pl. 19, figs. 4, 8), P. omega (Fortey, 1975,
pl. 20, fig. 6) and P. kolouros (Norford and Ross, 1978, pl.
2, fig. 9); the hypostomal association in P. erugata from
Nevada, USA has also been questioned (see Dean, 1973,
p. 21 and Fortey, 1975, p. 48). The systematic assessment
of Peraspis awaits the discovery of correctly associated
hypostome for the type species. In addition, morphologic
features of P. lineolata that deviate from those of typical
nileids and other included species need to be resolved in a
phylogenetic context, which may lead to modification of
the concept and familial position of Peraspis.
Since cf. Peraspis kujandensis from the Zhuozishan
area (see below) has a nileid glabellar tubercle and a
thoracic axial configuration as seen in Symphysurus
klimoliensis, it is retained in the Nileidae.
cf. Peraspis kujandensis (Chugaeva, 1958)
Figs. 2c, 5a–5i, 5l
Synonymy: 1958 Symphysurus kujandensis Chugaeva,
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1958, p. 68, pl. 7, figs. 15, 17–19, non fig. 16 [? =
Damiraspis margiana Ghobadi-Pour et al., 2009].
Figured specimens: Exoskeleton lacking free cheeks
(OCGM-Inv. 1465), two cranidia (OCGM-Inv. 1314,
1478) and thoraco-pygidium (OCGM-Inv. 1322, 1370).
Description: The subtrapezoical cranidium has a
rounded anterior margin. The anterior branches of the
facial suture are relatively strongly convex laterally; the
posterior branches are straight and run obliquely at about
30° from the exsagittal line for most of its length then
smoothly turn at an obtuse angle of about 135° in the
distal one-quarter. There is no anterior cranidial border
and preglabellar furrows are present. The axial furrows are
parallel-sided and shallow, shallower along the anterior
half of the postocular areas of the fixigenae and mostly
impressed away from the facial suture; they are not
impressed in most of the frontal area, but strongly
divergent abaxially for a short distance immediately
anterior to the palpebral lobes. The frontal area slopes
down steeply. The glabella behind the frontal area is
weakly convex and horizontal; the median node is small
and located at the level of the posterior end of the
palpebral lobes. Up to six pairs of small muscle insertion
areas are recognized along the glabellar crest. The
occipital ring is elongate (tr.) spindle-shaped and the
occipital furrow is shallow and wide and disappears
sagittally. The palpebral lobes are semi-circular in out-line
and flat with a length (exsag.) of 26% of the cranidial
length and the mid-palpebral point slightly posterior to the
mid-cranidial length; the anterior end is located more
adaxially than the posterior end. The postocular area of the
fixigenae is triangular. Librigena and hypostome are
unknown.
The thorax has eight segments, with a sagittal length
about one-third of exoskeletal length. The axial furrows
are shallow and obliquely directed posteriorly in each
segment, defining elongate (tr.) trapezoidal axial rings.
The axial region is weakly convex and gently tapers
posteriorly, with a maximum width of 28% of thoracic
width at the first segment; a goggle-shaped lobe and
furrow are present in each axial rings, as in Symphysurus
klimoliensis. The pleurae are horizontal and then they
slope gently down distally from the fulcral line; the pleural
furrows are diagonal and shallow. The anterior pleural
band is strongly raised as an elongate triangular ridge and
the posterior pleural band is moderately convex; the ridges
downslope anteriorly to form articulating facets. The
fulcrum of the first pleura is located halfway along the
posterior cranidial margin; fulcral lines gently diverge
posteriorly from the first to the fourth pleurae and are
parallel-sided from the fourth to the eighth pleurae.
Pleurae proximal to the fulcral line are ornamented with
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fine, transverse terrace lines. The doublure is nearly half
of the pleural width and ornamented with more widely
spaced terrace lines subparallel to the lateral margin.
The pygidium is semicircular with a relatively straight
anterior margin, length 46% of width. The axial furrows
are shallow and slightly curved adaxially to define a
funnel-shaped axis, which is narrow, 24% of pygidial
width. Five axial rings and a terminal piece are
recognized; the inter-ring furrows are faintly impressed.
The pleural field is weakly convex; only the anteromost
pleural furrow is impressed. The marginal border is
narrow, of uniform width and ornamented with weakly
developed fine terrace lines; the border furrow is shallow.
The doublure, indicated by paradoublural line in some
specimens (e.g., Fig. 5a) is narrow with the lateral
extremity of the inner margin located at the distal 21% of
half of the pygidial width and it slightly widens
posteriorly; sagittally it is indented into the posterior twothirds of the doublure length.
Remarks: Chugaeva (1958) erected Symphysurus
kujandensis from Kazakhstan based on partially
articulated specimens (pl. 7, figs. 15–19). Its cranidium is
indistinguishable from the Zhuozishan cranidia, except for
slightly larger palpebral lobes and a wider outline; these
are considered to be due to preservation and/or ontogeny.
The thoraco-pygidia are also indistinguishable from the
Zhuozishan specimens. The second associated cranidium
(fig. 16) is not a nileid, but an asaphid (compare with
Damiraspis margiana Ghobadi-Pour et al. 2009, figs.
10D–E).
From the co-occurring Symphysurus klimoliensis (Lu in
Lu et al., 1976), it is readily distinguished by its smaller
palpebral lobes (exsagittal length is 26% of cranidial
length and 39% in S. klimoliensis), a narrower thoracic
and pygidial axial regions (pygidial axis width is 24% of
pygidial width and 33% in S. klimoliensis), a semicircular
and shorter (sag.) pygidium (length is 46% of width and
58% in S. klimoliensis) with a relatively straight anterior
margin, and a longer (tr.) inner horizontal thoracic pleural
portion. From Poronileus, it clearly differs in having
smaller palpebral lobes, a semicircular, sagittally much
shorter pygidium (length is 67% in Poronielus) with a
narrower marginal border, and narrower doublure.
Of Peraspis species, the Zhuozishan species is most
similar to P. erugata from Spitsbergen (Fortey, 1975, pl.
19, figs. 1–9, 11). However, it has a longer (exsag.)
posterior area of the fixigenae, smaller palpebral lobes, a
shallower and narrower pygidial marginal border, a
narrower pygidial axis, which is 24% of pygidial width
(30% in P. erugata), a narrower pygidial doublure with
the inner margin at distal 21% of pygidial width (30% in
P. erugata) and eight thoracic segments (seven in P.
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erugata).
The cranidia of two Poronileus species, P. angustus
and P. miboshanensis from Ningxia erected by Zhou
(Zhou et al., 1982, pl. 66, fig. 13, pl. 67, fig. 2), are as
similar to those of this species as in S. klimoliensis. A
correctly associated pygidium is needed to provide
information for taxonomic assessment (see above).
Peraspis is one of a few nileid genera that has genal
spines and a lateral librigenal border. Fortey and
Chatterton (1988) interpreted their presence as a probable
secondary attainment from primitive nileids, which lack
them. The lack of a genal spines and border in the
Zhuozishan species (e.g., Chugaeva, 1958, pl. 7, fig. 15)
leads us to provisionally assign it to Peraspis.
4.6 Taxon 6
Family Raphiophoridae Angelin, 1854
Subfamily Raphiophorinae Angelin, 1854
Genus Ampyx-- Dalman, 1827
Type species: Ampyx nasutus Dalman, 1827 from
Asaphus expansus Biozone or A. raniceps Biozone of the
Asaphus Limestone, upper Arenig Series, Västanå,
Östergötland, Sweden; by monotypy.
Ampyx gongwusuensis sp. nov.
Figs. 2d, 6a–6j, 6n–6o
Derivation of name: After “Gongwusu,” a county near
the sampling locality.
Holotype: Exoskeleton lacking free cheeks (OCGMInv. 1464, Figs. 6e–6f).
Type horizon and locality: Middle Ordovician
Klimoli Formation, exposed at a foothill located between
Laoshidan and Gongwusu counties, south of Wuhai,
Zhuozishan area, Inner Mongolia, China.
Figured specimens: Six exoskeletons lacking free
cheeks (OCGM-Inv. 1366, 1464, 1429, 1461, 1463, 1346),
exoskeleton with displaced free cheeks and hypostome
(OCGM-Inv. 1311) and cephalo-thorax (OCGM-Inv.
1460).
Diagnosis: Species with pear-shaped glabella; front
end situated at level of anterior cranidial border furrow in
dorsal view. Subtriangular pygidium with narrow axis and
distinct rim along pleural field margin. Exoskeletal surface
smooth except for pygidial marginal border ornamented
with fine terrace lines.
Description: The exoskeleton (excluding frontal
glabellar spine and librigenae) is elliptical and of low
convexity. The cranidium is subtriangular; the facial
suture is straight and runs obliquely posteriorly and turns
more posteriorly at the level of the anterior one-quarter of
cranidial length; the posterolateral corner is rounded. The
anterior cranidial border -is narrow, short (tr.) and slightly
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arched dorsally; the anterior cranidial border and the
preglabellar furrow cross each other sagittally, forming an
‘X’ in anterior view. The axial furrows are moderately
deep but shallower in the posterior half. A pair of slit-like
anterior pits are located midway between the glabellar
front end and the level of the maximum glabellar width.
The glabella is pear-shaped and of high convexity, with a
maximum width of 26% of cranidial width; the S1 is pitlike and located at the level of the minimum glabellar
width; the L1 is subcircular. Two pairs of muscle insertion
areas are present in the posterior half of the glabella; they
are subcircular and slightly depressed, located on the
glabellar side but away from the axial furrows and within
the posterior half of the glabella; the posterior one is
immediately anterior to L1 and smaller than the anterior
one. Two additional pairs of small muscle insertion areas
are recognized in some specimens, located within the
anterior half of the glabella and posterior to the level of
maximum glabellar width; these anterior smaller pairs are
closer to the axial furrows. The glabellar frontal spine is
slender, circular in cross section and projecting
horizontally, with an observed maximum length of 35% of
cranidial length. The glabellar front beneath the spine is
short and vertical in lateral view. The occipital ring has a
straight anterior margin and a convex posterior margin,
divided into a pair of elongate (tr.) anterior lobe and a rimlike posterior lobe; the occipital furrow is shallow and
deepens abaxially to delineate posterior end of the L1. The
fixigenae are moderately convex and gently slope down
distally; a pair of weakly developed ridges run across the
fixigenae from the axial furrows at the level of the midglabellar length to the deep distal pit of the posterior
cranidial border furrow; the ridges are weakly convex
anterolaterally and become indistinct near the axial
furrows. The bacculae are small, rounded, weakly
developed and located immediately abaxial to the L1. The
posterior cranidial border is rim-like; it runs horizontally
and then slopes steeply down distally from the distal
quarter of cranidial width and continues into the rim-like
posterior lobe of the occipital ring. The posterior cranidial
border furrows widen and deepen distally with a very
distinct rounded pit at the distal end. The cranidial surface
is smooth.
The librigenal lateral border is wider than the anterior
cranidial border and it narrows posteriorly; the librigenal
spine is straight and long. The hypostome bears maculae
and has a relatively wide posterior border.
The thorax has six segments; the length is 29% of
exoskeletal length and a width of 91% of the cranidial
posterior margin width. The lateral margin is strongly
convex outward with maximum curvature at the boundary
between the second and third (from the anterior) segments;
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the anterolateral end of the first segment is located at the
point where the posterior cranidial border abruptly begins
to slope down distally. The axis is parallel-sided and 21%
of maximum thoracic width; the articulating furrow is
shallow and deepens distally. The pleurae are straight (tr.)
and flat; the anteromost pleural furrow is weakly sinuous
and of relatively uniform width; the posterior pleural
furrows widen distally; a narrow ridge is present along the
lateral end of each pleura; the distal end is bent steeply
downward. The surface is smooth.
The pygidium is subtriangular with the length 45% of
width and 30% of exoskeletal length; the lateral margin is
slightly convex outward. The axis uniformly tapers
posteriorly and is narrow (21% of pygidial width); the
posterior end reaches the rim along the plerual field
margin. Up to 18 axial rings are recognized; a pair of
circular muscle impression areas are present at the distal
end of each axial ring (visible only in internal mold); interring furrows are faintly impressed. The pleural field is flat
and gently slopes down posteriorly; a narrow but distinct
rim, raised above the pleural field, is developed along the
margin. The pleural furrows are straight and shallow; the
anteromost one is most distinct and slightly curved
posteriorly; a narrow straight ridge is present behind each
pleural furrow; the interpleural furrows are imperceptible.
The marginal border slopes steeply down and is of
uniform width; the posterior margin arches moderately
upward in posterior view. The pygidial surface is smooth,
except for the marginal border, which is ornamented with
fine terrace lines subparallel to the pygidial margin.
Remarks: This new species differs from the type
species, Ampyx nasutus Dalman, 1827 (Whittington, 1950,
pl. 74, figs. 3–9) in having a narrower axial region,
shallower muscle impressions on the glabella, an abaxially
convex facial suture, which is relatively straight in A.
nasutus, a much less strongly curved anteriormost pygidial
pleural furrow, and a much more distinct rim along the
pygidial pleural field margin.
Of the several Ampyx species from China, the
Zhuozishan species is most comparable to Ampyx
abnormalis Yi, 1957 (Peng et al., 2001, pl. 3, figs. 18–24,
pl. 4, figs. 1–5; Lu, 1975, pl. 39, figs. 5–11, pl. 40, figs. 1–
7; Zhou et al., 1984, figs. 6a–b). However, it has a
narrower axial region, a glabellar front end (excluding
frontal spine) situated at the anterior cranidial margin
furrow, whereas in A. abnormalis, the front end lies
anterior to anterior cranidial margin, a sagittally longer
pygidium with a much more distinct rim along the
relatively straight pleural field margin, and a much longer
genal spine. Ampyx hastatus and Ampyx triangularis from
Ningxia (Zhou et al., 1982, pl. 69, figs. 7–8) have a much
wider glabella, which protrudes anteriorly far beyond the
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cranidial margin; the features of these two species are
considered more consistent with those of Rhombampyx
(compare with Rhombampyx yii, Turvey, 2007, pl. 12,
figs. 2–3, 7). Ampyx puntolineatus from Jilin (Zhou and
Fortey, 1986, pl. 12, figs. 7, 8, 10, 12, 18) is distinguished
by its strongly forward-tapering glabella and row of pits
along the pygidial pleural and interpleural furrows. Ampyx
chinensis from Sichuan (e.g., Lu et al., 1965, pl. 126, fig.
4) and Ampyx reedi from Yunnan (e.g., Lu et al., 1965, pl.
127, fig. 21) are based on too inadequate and poorly
preserved material for comparison. A pygidium of Ampyx
nanjiangensis from Xinjiang (Zhang, 1981, pl. 73, fig. 10)
has a distinct rim along the pleural field margin as does A.
gongwusuensis, but it is sagittally shorter and has a wider
axis. Two pygidia that are associated with Mendolaspis
paradoidyx from Xinjiang (Zhang, 1981, pl. 74, figs. 9–
10) have a narrow axis and a distinct rim, but the pygidia
are sagittally shorter than the Zhuozishan pygidia.
Turvey (2007) noted that even relatively well-known A.
abnormalis and R. yii each might represent more than one
taxon because their recorded stratigraphic occurrences are
long and they are based on rather effaced and poorly
preserved material. Well-preserved material of A.
gongwusuensis reveals following morphologic details
(Fig. 2d) that are not observed in other Chinese Ampyx
species, including A. abnormalis, but are common even in
some other raphiophorine genera. The preglabellar furrow
sagittally crosses the anterior cranidial border furrow to
form an ‘X’ in anterior view (e.g., Fig. 6g; Ampyx
spongiosus, Fortey, 1975, pl. 22, fig. 1; Rhombampyx
tragula, Fortey, 1975, pl. 28, fig. 3; Ampyxoides
semicostatus, Whittington, 1965, pl. 13, fig. 4;
Cnemidopyge costatus, Nielsen, 1995, fig. 253F). The
glabellar front in lateral view is short and vertical beneath
the frontal spine (e.g., Fig. 6j; R. tragula, Fortey, 1975, pl.
28, fig. 9). The distinct pit is present at the distal extremity
of the posterior cranidial border furrow (e.g., Fig. 6e;
Ampyx delicatulus, Fortey, 1975, pl. 25, fig. 4;
Rhombampyx yii, Turvey, 2007, pl. 12, fig. 2). A pair of
faintly raised ridges runs across the fixigenal field (e.g.,
Figs. 6a, 6f, 6h; A. spongiosus, Fortey, 1975, Nielsen,
1995, 1995, fig. 257H). The occipital ring is divided into a
pair of elliptical anterior lobes and a rim-like posterior
lobe, which continues into the rim-like posterior cranidial
border (e.g., Fig. 6g; Lonchodomas clavulus, Whittington,
1959, pl. 32, fig. 4; L. tenuis, Nielsen, 1995, fig. 257H);
the rim-like fusion of occipital ring and border is
considered diagnostic to Raphioampyx (Turvey, 2007). A
narrow, straight ridge is developed immediately behind
each pygidial pleural furrow (e.g., Fig. 6a; A. spongiosus,
Fortey, 1975, pl. 23, fig. 1; A. semicostatus, Whittington,
1965, pl. 12, fig. 10).
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Of these taxa outside China, A. gongwusuensis is
cranidially most similar to Ampyx porcus from
Spitsbergen (e.g., Fortey, 1975, pl. 24, fig. 1) and
Lonchodomas tenuis (e.g., Nielsen, 1995, fig. 257A) and
pygidially to Lonchodomas normalis (e.g., Whittington,
1965, pl. 10, fig. 7). However, A. porcus has distinct rows
of pits along the pygidial pleural and interpleural furrows
and Lonchodomas is differentiated by having a frontal
glabellar spine with a subquadrate cross-sectional outline
and five thoracic segments. This complexity of similarities
needs to be resolved to soundly differentiate the
raphiophorine genera.
4.7 Taxon 7
Ampyx cf. abnormalis Yi, 1957
Fig. 6k–m
Figured specimens: Thoraco-pygidium with cephalic
outline (OCGM-Inv. 1418) and cranidium (OCGM-Inv.
1524).
Remarks: The thoraco-pygidium differs from that of
Ampyx gongwusuensis in having a sagittally shorter
pygidium with a wider axis and a more posteriorly located
maximum thoracic width, which is positioned in the third
segment but is at the posterior end of the second segment
in A. gongwusuensis (compare with Fig. 6d). The
associated cranidium also differs in having a more
rounded cranidial outline, a wider frontal spine base, and
the glabellar front protruding beyond the anterior cranidial
margin. In regard to cranidial and pygidial outlines, this
species is comparable to Ampyx abnormalis (compare with
Lu, 1975, pl. 40, figs. 1, 4 and Zhou et al., 1984, figs. 6a–
6b) but it has a much narrower thoracic and pygidial axial
region, much shorter thoracic pleurae, and less strongly
impressed anteromost pair of pygidial pleural furrows.
There is no cranidium in A. abnormalis shown in other
studies that clearly shows the glabellar frontal spine like
that of the present cranidium. The Zhouzishan taxon is
provisionally associated with A. abnormalis.
4.8 Taxon 8
Ampyx sp. indet.
Fig. 7e–f
Figured specimens: Cranidium (OCGM-Inv. 1431).
Remarks: This species represented by a single
cranidium differs from Ampyx gongwusuensis in having an
anterior cranidial margin that is longer (tr.) and curved
backwards sagittally. It is comparable to cranidia in
Mendolaspis paradoidyx from Xinjiang (Zhang, 1981, pl.
74, figs. 7–8) but it has a much shorter (tr.) anterior
border. Lu (1975) figured several smaller cranidia of
Ampyx abnormis (pl. 39, figs. 5–9), which are similar to
the present cranidium. These cranidia lack the glabellar
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frontal spine and have an anteriorly convex anterior
cranidial margin; however, it cannot be determined
whether or not the present cranidium lacks the spine.
4.9 Taxon 9
Genus Abulbaspis-- Zhou and Zhou, 2006
Type species: Bulbaspis ordosensis Lu in Lu et al.,
1976 from the Middle Ordovician Klimoli Formation,
Zhuozishan area, Inner Mongolia, China; by original
designation.
Abulbaspis ordosensis (Lu in Lu et al., 1976)
Fig. 7a–d.
Holotype: Exoskeleton (23936, Lu in Lu et al., 1976,
pl. 13, fig. 6) housed in Nanjing Institute of Geology and
Palaeontology.
Type horizon and locality: Middle Ordovician
Klimoli Formation, Wulalike canyon, southern end of
Gangdeer Mountains, south of Wuhai, Inner Mongolia,
China.
Figured specimens: Exoskeleton lacking free cheeks
(OCGM-Inv. 1541).
Remarks: The present specimen only differs from the
holotype of Abulbaspis ordosensis (Lu et al., 1976, pl. 13,
fig. 6) in having a larger frontal glabellar bulb with a
shorter connective neck. The difference is considered as
intraspecific since many Abubaspis and Bulaspis species
display a similar variation (e.g., Abulbaspis ovulum
Chugaeva, 1958, pl. 2, figs. 6–8; Bulbaspis mirabilis
Chugaeva, 1958, pl. 3, figs. 1–2).
This species is nearly indistinguishable from Ampyx
gongwusuensis. It differs in having a spherical frontal
glabellar bulb with a short connective neck (a spine in the
latter), a glabellar front protruding slightly further beyond
the anterior cranidial margin, a wide triangular depression
adaxial to a pair of ridges in the anterior fixigenal field,
and an entire posterior pygidial margin (a dorsally-arched
margin in the latter). If the frontal glabellar bulb and
connective neck are not preserved, it is likely that these
differences would be interpreted as intraspecific within A.
gongwusuensis.
It is possible that the differences including the spherical
bulb might be related to sexual dimorphism. Fortey and
Hughes (1998) interpreted a bulb in the preglabellar field
as a brooding pouch. Although it is a direct extension of
the glabella, the spherical bulb in A. ordosensis might
represent another type of brooding device. Since the
specimen of A. ordosensis occurs in a bed 24 m higher
than the horizon where A. gongwusuensis occurs, to
confirm this possible interpretation of sexual dimorphism
awaits further collection.
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Fig. 6. Photographs of specimens of the Raphiophoridae: (a–j), (n–o), Ampyx gongwusuensis sp. nov.; (k–m), Ampyx cf. abnormalis
Yi, 1957; scale bars = 5 mm.
(a–c), Exoskeleton lacking free cheeks, OCGM-Inv. 1366, (a) dorsal view, (b) anterior view, (c) posterior view. (d), Cephalo-thorax, OCGM-Inv. 1460, dorsal
view. (e–f), Exoskeleton lacking free cheeks, OCGM-Inv. 1464, holotype, (e) dorsal view, (f) magnified lateral view of cranidium (note four circular muscle
impression areas alongside glabella). (g), exoskeleton lacking free cheeks (latex cast), OCGM-Inv. 1429, oblique anterior view. (h–i), Exoskeleton with displaced
free cheeks and incomplete hypostome, OCGM-Inv. 1311, (h) dorsal view, (i) lateral view (note the free cheek and lateral border of posterior two thoracic segments). (j), Exoskeleton lacking free cheeks, OCGM-Inv. 1461, magnified lateral view of cranidium. (k), Incomplete exoskeleton, OCGM-Inv. 1418, dorsal view.
(l–m), Cranidium, OCGM-Inv. 1524, (l) dorsal view, (m) lateral view. (n), Exoskeleton lacking free cheeks (external mold), OCGM-Inv. 1463, magnified view of
glabellar frontal spine. (o), Exoskeleton lacking free cheeks, OCGM-Inv. 1346, magnified view of muscle impression areas on pygidial axial rings.
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Fig. 7. Photographs of specimens of the Raphiophoridae: (a–d), Abulbaspis ordosensis (Lu in Lu et al., 1976); (e–f), Ampyx? sp.
indet.; scale bars = 5 mm.
(a–d), Exoskeleton lacking free cheeks, OCGM-Inv. 1541, (a) dorsal view, (b) lateral view, (c) anterior view, (d) posterior view. (e–f), Cranidium, OCGM-Inv.
1431, (e) dorsal view, (f) oblique anterior view.
4.10 Taxon 10
Family Telephinidae Marek, 1952
Genus Telephina Marek, 1952
Telephina sp. indet.
Fig. 5m
Figured specimens: Incomplete cranidium (OCGMInv. 1404).
Remarks: A single poorly preserved cranidium shows
morphology of Telephina including a short (sag.) glabella
with rounded anterior margin, a large occipital ring with a
deep occipital furrow, tubercles on glabella, and reticulate
pits on the fixigena (compare with Telephina bicuspis
(Angelin, 1854) from Norway, Nikolaisen, 1963, pl. 1,
figs. 1–10). The poor preservation prevents us from further
assessing the species.
5 Conclusion
A trilobite assemblage collected from the Middle
Ordovician Klimoli Formation of the Zhuozishan area,
Ordos Basin, Inner Mongolia was systematically
described. The assemblage is primarily composed of the
raphiophorids and nileids. New morphological data
revealed by the systematic revision need to be
incorporated to evaluate systematics of important Chinese
raphiophorid taxa such as Ampyx and Abulbaspis, and
nileid taxa such as Symphysurus and Poronileus.
Acknowledgements
The authors are grateful to Beatriz G. Waisfeld for
giving constructive comments on an earlier version of the
manuscript. We also thank for anonymous reviewers for
reviewing the manuscript and Susan Turner for improving
English of the taxonomic description sections. This work
is financially supported by a grant from the Basic
Research Project (GP2016-013) of KIGAM to S.-B. Lee
and the Korea Research Foundation (Grant No. KRFR1A4007-2010-0011026) to D.-C. Lee.
Manuscript received May 24, 2015
accepted Oct. 3, 2016
edited by Fei Hongcai and Susan Turner
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About the first author
Seung-Bae LEE, male; born in May 1977, Seoul, Republic of
Korea; graduated from Seoul National University (Ph.D) in
2008; curator in natural history division at Gwacheon
National Science Museum, Korea (2010–2014); currently
senior researcher in Geological Research Center of Korea
Institute of Geoscience and Mineral Resources, Daejeon,
Korea; interested in Early Paleozoic trilobites and echinoderm
paleontology, biostratigraphy, paleogeography, and evolution;
currently serving as academic secretary of the Paleontological
Society of Korea and professional advisor in paleontology of
the Geological Society of Korea. Email: sblee@kigam.re.kr