A new arthropod from the Chengjiang Lagerstätte, Early Cambrian, southern China

Abstract

A new genus and species of lightly sclerotized arthropod with an Aglaspis-like tagmosis, Kwanyinaspis maotianshanensis, is described from the well-known Chengjiang Lagerstätte, Early Cambrian, Yunnan, South China, on the basis of a single exquisitely preserved specimen. The dorsal exoskeleton, showing a poorly defined axial region but lacking axial furrows, is composed of a cephalic shield, 12 trunk tergites with well-developed pleural spines and a tail spine. A pair of ventral eyes is present beneath the first quarter of the cephalic shield. Appendages are preserved in remarkable detail; the basis is a large, flat plate, and bears gnathobases ventrally; the endopod is articulated with the abaxial edge of the basis and comprises seven articles; the exopod is flap-like and articulated along the entire length of the dorsal margin of the basis. Kwanyinaspis is provisionally assigned to Aglaspidida due to its overall resemblance to Aglaspis.

Full text

0311/5518/2005/02185-10 $3.00 © AAP
.
A new arthropod from the Chengjiang Lagerstätte,
Early Cambrian, southern China
XINGLIANG ZHANG and DEGAN SHU
ZHANG, X.-L. & SHU, D.-G., 30.9.2005. A new arthropod from the Chengjiang Lagerstätte,
Early Cambrian, southern China. Alcheringa 29, 185-194. ISSN 0311 5518.
A new genus and species of lightly sclerotized arthropod with an Aglaspis-like tagmosis,
Kwanyinaspis maotianshanensis, is described from the well-known Chengjiang
Lagerstätte, Early Cambrian, Yunnan, South China, on the basis of a single exquisitely
preserved specimen. The dorsal exoskeleton, showing a poorly defined axial region but
lacking axial furrows, is composed of a cephalic shield, 12 trunk tergites with well-
developed pleural spines and a tail spine. A pair of ventral eyes is present beneath the
first quarter of the cephalic shield. Appendages are preserved in remarkable detail; the
basis is a large, flat plate, and bears gnathobases ventrally; the endopod is articulated with
the abaxial edge of the basis and comprises seven articles; the exopod is flap-like and
articulated along the entire length of the dorsal margin of the basis. Kwanyinaspis is
provisionally assigned to Aglaspidida due to its overall resemblance to Aglaspis.
Xingliang Zhang [xlzhang@pub.xaonline.com] and Degan Shu, Early Life Institute
and Department of Geology, and Key Laboratory for Continental Dynamics of the
Education Ministry, Northwest University, Xian, 710069, P. R. China; received 31.3.2004,
revised 22.7.2004.
Key words: Arthropoda, Aglaspidida, Kwanyinaspis, Early Cambrian, Chengjiang
Lagerstätte.
AGLASPIDIDS are a group of extinct arthropods,
generally regarded as stem group chelicerates
(Delle Cave & Simonetta 1991, Robison & Wiley
1995, Wills et al. 1995, 1997, 1998; Dunlop &
Selden 1997, Selden & Dunlop 1998). They are
known primarily from the Cambrian, but an
Ordovician form was described by Fortey &
Rushton (2003). Aglaspidids are characterized
by a phosphatic exoskeleton with a pitted texture,
11 trunk tergites and a tail spine; the most distinct
structure are the postventral plates (Hesselbo
1992, Dunlop & Selden 1997). The appendages
are incompletely known from three species of
body fossils, Aglaspis spinifer Raasch, 1939
(Briggs et al. 1979, Hesselbo 1992); Flobertia
kochi Hesselbo, 1992; and Khankaspis
bazhanovi Repina & Okuneva, 1969, and also
trace fossil evidence (Hesselbo 1988). However,
a number of Cambrian non-trilobite arthropods
lacking some typical aglaspidid features, but
resembling Aglaspis in different ways, have
traditionally been also assigned to Aglaspidida
(see Størmer 1955, Hesselo 1989, Waggoner 2003
and references therein). As Dunlop & Selden
(1997) pointed out, Aglaspidida has now become
something of a “bucket taxon”. No Aglaspis-like
arthropod has been reported from the
Chengjiang Lagerstätte or other Early Palaeozoic
deposits of China. The putative Carboniferous
aglaspidid, Singlaspis Hong & Niu, 1981, from
Shanxi, China, looks more like an arachnid. We
here report the discovery of the first Aglaspis-
like arthropod from China, based on a single
almost complete unique specimen. The overall
shape resembles Aglaspis, especially the type
species Aglaspis barrandei Hall, 1862.
Therefore, it is provisionally assigned to the
Aglaspidida.
Preservation
The specimen is almost complete and is
dorsoventrally compressed parallel to the
bedding plane. The split passes through the

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ZHANG & SHU
Fig. 1. Kwanyinaspis maotianshanensis Zhang & Shu gen. et sp. nov., holotype ELI-2004001, part, Helinpu
Formation, Yu’anshan Member (Eoredlichia Zone), Early Cambrian, Maotianshan section, Chengjiang County,
Yunnan Province, South China, showing the outline, impressions of eyes and appendages. Scale bar = 1 cm.
dorsal surface of the animal. The fossil is
preserved in a finely laminated, maize-coloured
mudstone. The exoskeleton and appendages
appear to be coated by a film of fine-grained

ALCHERINGA 187NEW EARLY CAMBRIAN CHENJIANG ARTHROPOD
particles, sandy-beige in colour, standing out
well against the yellow matrix. In bore samples
or when tracing beds from many localities of the
Chengjiang fossils to deep ravines, the
fossiliferous stratum is dark grey. Weathering
has certainly played a role in the final appearance
of the fossil. Many other Chengjiang arthropods,
e.g. Pygmaclypeatus (Zhang et al. 2000),
Squamacula (Zhang et al. 2004), show similar
preservation in this respect. The reddish films,
probably ferric oxide-stained, probably arise from
oxidation of finely dispersed pyrite on fossil
surfaces. The origin of the pyrite is presumed to
have been produced by the activities of bacteria
during early diagenesis, which colonized the
surface of carcasses (Chen & Erdtmann 1991).
Bengtson & Hou (2001) reported that the
Chengjiang fossils were much richer in iron than
the matrix. However, a complete taphonomic
study is still lacking for the reddish appearance
of the Chengjiang fossils.
Dark spots are densely distributed on the
second and third trunk tergites, and sparsely on
the right genal angle of the cephalic shield and
the exopod flap in the left genal angle.
Additionally, a dark patch, irregular in shape,
occurs on the surface of the right fourth and
fifth tergites of the trunk. It appears that these
dark spots and the patch are not original
structures of the animal, but their exact origin
remains unclear.
Systematic palaeontology
The prefix ELI refers to the collections of the Early
Life Institute and Department of Geology, and Key
Laboratory for Continental Dynamics of the
Education Ministry, Northwest University, Xian.
Phylum ARTHROPODA Siebold & Stannius, 1845
Subphylum ARACHNOMORPHA sensu Cotton
& Braddy, 2004
Order ?AGLASPIDIDA Raasch, 1939 emend.
Briggs, Bruton & Whittington, 1979
Kwanyinaspis gen. nov.
Type species. Kwanyinaspis maotianshanensis
sp. nov.
Diagnosis. Exoskeleton non-mineralized,
consisting of a cephalic shield, 12 trunk tergites
and a tail spine; stalked eyes on the ventral side;
appendages biramous and uniform throughout
the body, the basis bearing gnathobases, exopod
flap-like and endopod with seven articles.
Etymology. A conflation of Kwan-yin and Aspis.
Kwan-yin, Chinese “the Bodhisattva of mercy”
in Buddhism; Aspis (feminine), Greek “shield”,
referring to the stout shield-like outline of the
animal. Gender feminine.
Kwanyinaspis maotianshanensis sp. nov. (Figs
1-3)
Type and only known specimen. ELI - 2004001 is
deposited in the Early Life Institute and
Department of Geology, Northwest University,
Xian, PR China (prefixed ELI).
Stratigraphy and locality. Helinpu (previously
Qiongzhusi, old spelling style: Chiungchussu)
Formation, Yu’anshan Member (Eoredlichia
Zone), Early Cambrian, in the Maotianshan
section (the type locality of the Chengjiang
Lagerstätte), Chengjiang County, Yunnan
Province, South China. The detailed locality
information was given by Zhang et al. (2001).
The absolute age has been estimated to fall
between 530 and 520 Ma (see Babcock et al.
2001 and references therein).
Etymology. From Maotianshan, the mountain
where the fossil was found.
Description. The animal is rounded in outline,
slightly longer than broad. The maximum length
(sagittal) is about 60 mm; maximum width is
across the mid-length (third trunk tergite) of the
body, approximately 47 mm. The dorsal
exoskeleton is divided into a cephalic shield with
short genal spines, a trunk with 12 tergites and a
tail spine.
Tergites
Cephalic shield gently convex upward, semi-
elliptical in outline, genal spines short; maximum

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ZHANG & SHU
Fig. 2A-D. Kwanyinaspis maotianshanensis Zhang & Shu gen. et sp. nov., holotype ELI-12004001. A, counterpart.
B, detailed view of a limb in the left genal angle of part, showing distal portions of endopod and exopod flap, lamellae
and bristles. C, detailed view of the posteriormost portion of the trunk, showing posteriorly directed pleural spines of
the last four trunk tergites, tail spine and impression of possible postventral plates. D, detailed view of an almost
complete limb in the right of the trunk. Scale bars = 1 cm in A, = 5 mm in B-D. A, counterpart; B-C-D, part.
width lying between tips of genal spines, about
43 mm, sagittal length of 15 mm, approximately
30% of its width; posteromedian edge gently
convex backward; surface smooth, except for
wrinkles in the centre, which are a good indication
of light sclerotization. Wrinkles more or less

ALCHERINGA 189NEW EARLY CAMBRIAN CHENJIANG ARTHROPOD
concentrically arranged and thus define a
glabellar region (Figs 1, 2A, 3). A pair of tear-
shaped, dark impressions, moderate in size and
narrowing proximately, visible in the anterolateral
to the cephalic shield (Figs 1, 2A, 3). Dorsal
exoskeleton in these areas slightly convex
dorsally but smoothly continues with the
adjacent portions. Therefore, they certainly
represent a pair of ventral structures. Judging by
their shape and position, the dark impressions
most probably represent a pair of ventral eyes;
the narrower proximal portions are better
interpreted as stalks. The two bulges in the
cephalic shield are used to accommodate ventral
eyes.
Trunk broad and flat, widening gently until
the third tergite and tapers progressively toward
the rear from this tergite; axial region is ill-
defined, occupying one-third of the body width.
It consists of 12 tergites with low relief; pleural
spines well developed and posteriorly directed.
Tergites 1 to 4 have a similar width and length,
and short pleural spines; tergites 5 to 9 narrow
and shorten gradually backward. Tergite
boundaries difficult to follow after the ninth, but
three are indicated by pleural spines (Figs 2C,
3); each is dorsal to the tail spine, suggesting
they are pleural spines other than ventral
structures. Tergite shapes vary somewhat;
pleural areas of tergites 1 to 7 approximately
transverse to the body axis, the remainders being
more posterolaterally deflected; pleural spines
short in tergites 1 to 4 but become much longer
and strongly directed posteriorly in tergites 5 to
9, the last three are much more reduced in size
and decreasing backward in sagittal length.
Tail-spine sword-like, posterior portion
absent, apparently not extending much further
posteriorly (judging by the narrowing trend of
the preserved portion). Anterior end has a
distinct anterior expansion with a v-shaped
concavity inside, tentatively interpreted as the
impression of posteventral plates. Admittedly,
postventral plates in aglaspidids are paired
structures divided by a median sulcus which is
invisible in the present specimen. However, the
sulcus might be masked by the taphonomic
process, given that the exoskeleton is lightly
sclerotized, the specimen is split in dorsal view,
and the structure is actually a compressing mark
through the proximal portion of the tail spine.
Appendages
Appendages are preserved with remarkable detail
on a par with Misszhouia Chen et al., 1997, an
Chengjiang arthropod well-known for its splendid
preservation of appendages (Chen et al. 1997,
Hou & Bergström 1997, Zhang et al. in press).
When our specimen was first split, only distal
portions of limbs, both exopod and endopod,
were revealed, projecting beyond the anterior and
lateral margins of the cephalic shield (Figs 1, 3).
Among these, three short, linear structures occur
in front of the right anterolateral margin of the
cephalic shield where antennae are normally
located, but they seem dissimilar to antennae of
many other arachnomorphs, which are usually
long, multi-annulate and flagella-shaped (Hou &
Bergström 1997). Behind them at least two
exopods are present. Therefore, they might be
distal portions of endopods in the cephalon.
Additionally, in the same position of the left side
there is a large biramous limb. Presently, it is
uncertain weather Kwanyinaspis has antennae
or not.
To obtain the whole picture of an
appendage, portions of tergites in the right
anterior of the trunk were removed and a limb
probably attaching in the fourth trunk segment
was revealed (Figs 1, 2D, 3). This limb is
anteroposteriorly compressed, and bears a large
proximal element, the basis, from which the
endopod is a continuation. The basis has a large,
subrectangular endite, spinose on the
ventromedial edge, termed here the gnathobase.
The
endopod bears seven articles, the last being
a terminal spine. Articles 1 (next to the basis) to
3 are short and approximately equal in length,
about half the length of the basis, each of which
carries a strong, subtriangular projection, endite
(Figs 2D, 3). Article 4 is much narrower than the
proceeding ones, carrying a distally directed
spine. Articles 5 to 7 are more clearly revealed by
other limbs in the left anterior of the animal (Figs

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ZHANG & SHU
Fig. 3. Camera-lucida drawing of Fig. 1. Br, bristles fringed on the edge of the distal lobe of exopod; Bs, basis; Den,
distal portion of endopod; Dex, distal lobe of exopod flap; Eds, endites; Gb, gnathobases; Gl, glabella; Lm, lamellae on
the dorsal edge of the proximal lobe of exopod flap; Lve, left ventral eye; Pex, proximal lobe of exopod flap; Rve,
right ventral eye; T1-12, trunk tergites; Ts, tail spine; ?Vp, impression of possible postventral plates; Wrs, wrinkles.
1, 2B, 3). They are non-spinose, tapering
gradually to the tip. The
exopod is large, flap-
like, and is attached along the entire length of
the dorsal edge of the basis by a hinge. Proximal
portion narrow whereas distal portion extremely
swollen. No articulation visible between distal
1cm
Lve
Rve
Dex
Pex
Dex
Dex
Dex
Pex
Lm
Lm
Lm
Br
Bs
Wrs
Den
Den
?Den
T1
T2
T3
T4
T5
T6
T7
T8
T9
T10
T11
T12
Ts
?Vp
Gb
T4
T5
T3
Gl
Wrs
Eds

ALCHERINGA 191NEW EARLY CAMBRIAN CHENJIANG ARTHROPOD
and proximal lobes. A row of lamellae was
attached along the dorsal margin of the proximal
lobe, being closely-spaced, and appearing as
narrow, imbricated flat bands. Distal lobe carries
a fringe of bristles better preserved in a limb
projecting from the left genal angle of the
cephalon (Figs 1, 2B and 3).
Comparisons
Comparison with other arachnomorphs
Kwanyinaspis is readily distinguishable from
other non-trilobite arthropods in the Chengjiang
Lagerstätte by its well-developed, posteriorly
directed pleural spines especially in the posterior
trunk tergites, and its distinct tail spine. The
majority of the Chengjiang arachnomorphs, e.g.
naraoiids, helmetiids, Retifacies, Sinoburius, etc.
(see Hou & Bergström, 1997, Hou et al. 2004),
have a pygidium defined as multisegmental
posterior tagma (Fortey & Whittington 1989)
that is not present in Kwanyinaspis. Some do
have a posteromedial spine but it is projected
either from a tail shield as in Xandarella, or the
posteriormost tergite as in Cindarella; both taxa
have more trunk segments than Kwanyinaspis.
The Burgess Shale Emeraldella Walcott,
1912 resembles Kwanyinaspis in overall
appearance. It has a broad cephalic shield
followed by a trunk with about a dozen tergites
and a long tail spine (Bruton & Whittington
1983). Such an appearance is broadly similar to
Aglaspis. Indeed, Emeraldella was even
considered as an aglaspidid-like arthropod (see
Bruton & Whittington 1983 and references
therein). However, Kwanyinaspis is much
broader and has one segment fewer than
Emeraldella. Moreover, they are markedly
different in the construction of their trunk
appendages, particularly in the exopod, the distal
lobe in Emeraldella is much smaller, separated
from the proximal lobe by an articulation (see the
most recent reconstruction in Edgecombe &
Ramsköld 1999, fig. 11) that is not present in
Kwanyinaspis.
The construction of trunk limbs in
Kwanyinaspis is strikingly similar to that of
Naraoia spinosa (Zhang et al. in press): in both
taxa, the basis and proximal articles of the
endopod bear endites; the exopod is flap-like,
showing a narrow proximal lobe and a broad
distal lobe but no articulation. The similarities
are, perhaps, results of convergent evolution for
the marked difference in tergal morphology.
Comparison with other aglaspidids
About a dozen early Paleozoic arthropods,
varying considerably in outline, were referred to
the Aglaspidida (Størmer 1955, Repina & Okuneva
1969), including the two most recently described
forms (Fortey & Rushton 2003, Waggoner 2003).
Among them, Aglaspis barrandei (the type
species) provides the best comparison with the
new species, both having a broad outline, short
genal spines and very posteriorly deflected
pleural spines in the posterior portion of the trunk.
Kwanyinaspis differs from A. barrandei in its
ventral eyes and non-mineralized exoskeleton.
Additionally, Kwanyinaspis has one more trunk
tergite, i.e. 12 other than 11 tergites. However,
judging by the most complete specimen of A.
barrandei, there probably is a tergite hidden
below the cephalic shield, revealed by a
transverse linear trace in front of the posterior
margin of the cephalic shield (see Hesselbo 1992,
figs 2.1, 3). A similar linear trace also occurs in
Glypharthrus thomasi Walter, 1924 (see Hesselbo
1992, fig. 8.2-3). Most other aglaspidids are
distinct from Kwanyinaspis in their relatively
elongate body and less posteriorly deflected
pleural spines. It is unnecessary to cite all of them
here.
Appendages are known from three species
of aglaspidids: Aglaspis spinifer, Flobertia
kochi (Hesselo, 1992) and Khankaspis
bazhanovi (Repina & Okuneva, 1969), but are
not preserved in so much detail as those in
Kwanyinaspis. In Aglaspis spinifer and Flobertia
kochi, the anteriormost pair was described as
uniramous, perhaps antenniform, and the others
appendages were supposed to be biramous
(Briggs et al. 1979, Hesselbo 1992). However,
the outline is uncertain; the exopod and proximal
portion of endopod are missing. The revealed
distal portions show no significant difference
from those of Kwanyinaspis. Information

ALCHERINGA
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ZHANG & SHU
available is insufficient to make detailed
comparison. The photographic illustration of
Khankaspis bazhanovi is poor; the explanatory
drawing shows banded lamellae attached to a
slender shaft (Repina & Okuneva 1969, fig. 3),
markedly dissimilar to the exopod architecture
of Kwanyinaspis (Figs 1, 2D, 3).
Comparison with eurypterids
Kwanyinaspis is dissimilar to eurypterids in many
respects. Eurypterids have a much more
elongated outline and show marked regional
specialization in body segments and appendages
(Størmer 1955). The only notable similarity lies in
the same number of trunk segments. However,
an Early Cambrian arthropod from Bohemia,
Kodymirus Chlupác & Havlícek, 1965, resembles
Kwanyinaspis in tagmosis and has the same
number of trunk tergites. This taxon was
considered as an aglaspidid (Chlupác & Havlícek
1965) but was placed in the Eurypterida (Chlupác
1995). Again, Kwanyinaspis is distinguishable
from Kodymirus by its broad and round outline.
In addition, Kodymirus has much longer
prosomal appendages, about three-quarters of
the length of the appendage projecting beyond
lateral margins of the prosoma (Chlupác 1995). It
is not likely to be congeneric with Kwanyinaspis.
Discussion
Aglaspidids have generally been considered as
a distinct group of arthropods characterized by
phosphatic exoskeleton dorsally subdivided into
a cephalic shield with genal spines, 11 trunk
tergites, postventral plates and a tail spine
(Dunlop & Selden 1997, Selden & Dunlop, 1998).
Postventral plates have been regarded as an
autapomorphy for this group (Dunlop & Selden
1997, p. 229). Kwanyinaspis differs from this
diagnosis in that it has a non-mineralized
exoskeleton and one more trunk tergite. The
recently described Ordovician arthropod
Tremaglaspis may have a lightly sclerotized
exoskeleton based on wrinkles, clearly
taphonomic in origin, in the cephalic shield (see
Fortey & Rushton 2003, figs 1-3). However,
Tremaglaspis has postventral plates which was
considered as a strong synapomorphy between
it and Aglaspis (Fortey & Rushton 2003). The
number of trunk tergites is considered here to
have little phylogenetic importance because
Aglaspis barrandei and Glypharthrus thomasi
may have one more tergite hidden beneath the
cephalic shield (see comparison above). Further,
others, e.g. Chraspedops, may have fewer than
11 trunk tergites, at least in some specimens
(Hesselbo 1992, figs 16-19). Therefore, the intra-
specific variation in the number of trunk tergites
might have existed in aglaspidids.
The tagmosis, genal spines, pleural spines
and tail spine link Kwanyinaspis with the
Aglaspidida, and ventral eyes may also occur in
at least one member of aglaspidids, i.e.
Tremaglaspis (Fortey & Rushton 2003).
Unfortunately, appendages are poorly known in
species of aglaspidids and ventral structures
other than appendages remain unknown in
Kwanyinaspis. The assignment to the
Aglaspidida is tentative since some typical
aglaspidid features like the pitted texture on the
phosphatic exoskeleton and the unique pattern
of apodemes are absent in Kwanyinaspis.
Additionally, postventral plates, the
autapomorphy for the Aglaspidida, is
unconvincing in Kwanyinaspis, although there
is evidence suggesting that they might be
present. This character is also unconvincing in
at least one member of the less controversial
aglaspidids, i.e. Chraspedops (Hesselbo 1992),
and has not been identified in a recently
described arthropod Quasimodaspis Waggoner,
2003, with many typical aglaspidid features.
Acknowledgments
This work was funded by the Natural Science
Foundation of China (Grants NSFC-40332016 and
40402005), a Foundation for the Author of
National Excellent Doctoral Dissertation of PR
China (FANEDD). We thank Jason A. Dunlop
and Simon Braddy for reviewing the manuscript.
XZ gratefully acknowledges the Alexander von
Humboldt Foundation for the financial support
of a research visit in the Department of
Geobiology, Centre for Geosciences, University

ALCHERINGA 193NEW EARLY CAMBRIAN CHENJIANG ARTHROPOD
of Göttingen (GZG, Germany). Special thanks are
given to Professor Joachim Reitner for access to
numerous facilities in the GZG.
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