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Earliest fossil record of Corylophidae from Burmese amber and phylogeny of Corylophidae (Coleoptera: Coccinelloidea)

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The family Corylophidae is a moderately diverse coccinelloid beetle family. The fossil record of corylophid beetles is extremely sparse, with only one species formally described from the Eocene Baltic amber. Here we report a new corylophid genus and species, Xenostanus jiangkuni Li, Szawaryn & Cai gen. et sp. nov. , from mid-Cretaceous amber from northern Myanmar (ca. 99 Ma). Xenostanus is most distinctly characterized by the antenna with 10 antennomeres and the presence of metaventral and abdominal postcoxal lines. Our phylogenetic analysis suggested Xenostanus as sister to tribe Stanini. Based on its distinctive morphology and the phylogenetic results, Xenostanus is placed in the tribe Xenostanini Li, Szawaryn & Cai trib. nov.
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411
Earliest fossil record of Corylophidae from Burmese
amber and phylogeny of Corylophidae (Coleoptera:
Coccinelloidea)
Yan-Da Li1,2, Yu-Bo Zhang3, Karol Szawaryn4, Di-Ying Huang1, Chen-Yang Cai1,2
1 State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, and Center for Excellence in Life
and Paleoenvironment, Chinese Academy of Sciences, Nanjing 210008, China; Yan-Da Li [ydli@pku.edu.cn]; Di-Ying Huang [dyhuang@
nigpas.ac.cn]
2 School of Earth Sciences, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol, BS8 1TQ, United Kingdom
3 State Key Laboratory of Protein and Plant Gene Research, and Peking-Tsinghua Center for Life Sciences, Academy for Advanced
Interdisciplinary Studies, Peking University, Beijing 100871, China; Yu-Bo Zhang [yubozhang@pku.edu.cn]
4 Museum and Institute of Zoology, Polish Academy of Sciences, Wilcza 64, Warsaw, Poland; Karol Szawaryn [k.szawaryn@gmail.com]
http://zoobank.org/48AB3E3B-3928-49CA-B26D-4B22839FA7D5
Corresponding author: Chen-Yang Cai (cycai@nigpas.ac.cn)
Received 05 February 2022
Accepted 04 July 2022
Published 18 Augu 2022
Academic Editor Sergio Pérez-González, Mónica M. Solórzano-
Kraemer
Citation: Li Y-D, Zhang Y-B, Szawaryn K, Huang D-Y, Cai C-Y (2021) Earlie fossil record of Corylophidae from Burmese amber and phylogeny
of Corylophidae (Coleoptera: Coccinelloidea). Arthropod Syematics & Phylogeny 80: 411–422. https://doi.org/asp.80.e81736
Abstract
The family Corylophidae is a moderately diverse coccinelloid beetle family. The fossil record of corylophid beetles is extremely
sparse, with only one species formally described from the Eocene Baltic amber. Here we report a new corylophid genus and spe-
cies, Xenostanus jiangkuni Li, Szawaryn & Cai gen. et sp. nov., from mid-Cretaceous amber from northern Myanmar (ca. 99 Ma).
Xenostanus is most distinctly characterized by the antenna with 10 antennomeres and the presence of metaventral and abdominal
postcoxal lines. Our phylogenetic analysis suggested Xenostanus as sister to tribe Stanini. Based on its distinctive morphology and
the phylogenetic results, Xenostanus is placed in the tribe Xenostanini Li, Szawaryn & Cai trib. nov.
Key words
Corylophidae, Mesozoic, Myanmar, site-heterogeneous model, constrained phylogentic analysis
1. Introduction
Corylophidae, also known as the minute hooded beetles,
is a moderately diverse and cosmopolitan family in the
superfamily Coccinelloidea (Robertson et al. 2015), with
about 285 extant species in 27 genera (Robertson et al.
2013). Corylophids generally have a minute body, and the
ones with further miniaturization occur in several inde-
pendent lineages (Robertson et al. 2013; Polilov 2016;
Yavorskaya and Polilov 2016). Both larvae and adults of
corylophids feed on fungal spores and hyphae (Ślipiński
et al. 2010).
The internal classication and phylogeny of Corylo-
phidae have been generally satisfactorily studied. Bow-
Arthropod Syematics & Phylogeny 80, 2022, 411–422 | DOI 10.3897/asp.80.e81736
Copyright Yan-Da Li et al.: This is an open access article diributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrericted use, diribution,
and reproduction in any medium, provided the original author and source are credited.
Li et al.: Earlie fossil of Corylophidae
412
estead (1999) conducted a major revision of the family,
and produced a preliminary cladogram. Following the
transfer of Periptyctus Blackburn (originally in Endomy-
chidae) and Cleidostethus (originally in Coccinellidae)
to Corylophidae (Bowestead et al. 2001; Ślipiński et al.
2001), Ślipiński et al. (2009) performed a morpho logy-
based cladistic analysis and recognized two subfamilies,
Periptyctinae and Corylophinae, with the latter divided
into 10 tribes. Robertson et al. (2013) further revised the
phylogeny of the family based on the incorporation of
molecular evidence, with a new tribe, Stanini, separated
from Aenigmaticini.
The fossil record of Corylophidae is extremely sparse.
The only fossil species formally described was a member
of Clypastraea Haldeman from the Eocene Baltic amber
(Alekseev 2016). An occurrence of Corylophidae in the
Late Cretaceous amber was mentioned by Rasnitsyn and
Quicke (2002), although no further information was pro-
vided.
In the present study, we describe a well-preserved co-
rylophid species from the mid-Cretaceous Burmese am-
ber, which represent the earliest record of this family. The
robustness of the corylophid phylogeny by Robertson et
al. (2013) is also tested under a site-heterogeneous model.
The placement of the new fossil is nally evaluated under
implied weights parsimony with a constraining backbone
based on molecular evidence.
2. Materials and methods
2.1. Materials
The Burmese amber specimens studied herein (Figs 1–5,
S1) originated from amber mines near Noije Bum (26°20′
N, 96°36′ E), Hukawng Valley, Kachin State, northern
Myanmar. The holotype is deposited in the Nanjing In-
stitute of Geology and Palaeontology, Chinese Academy
of Sciences, Nanjing, China. The two paratypes are depo-
sited in the Leibniz-Institut zur Analyse des Biodiversi-
tätswandels (formerly the Geologisch-Paläontologisches
Institut und Museum der Universität Hamburg), Germa-
ny. The amber pieces were trimmed with a small table
saw, ground with emery papers of dierent grit sizes, and
nally polished with polishing powder.
2.2. Fossil imaging
Photographs under incident light were taken with a Zeiss
Discovery V20 stereo microscope or a Leica M205A ste-
reomicroscope. Confocal images were obtained with a
Zeiss LSM710 confocal laser scanning microscope, using
the 488 nm Argon laser excitation line. Images under inci-
dent light were stacked in Zerene Stacker 1.04. Confocal
images were stacked with Helicon Focus 7.0.2 and Ado-
be Photoshop CC. Microtomographic data were obtained
with a Zeiss Xradia 520 Versa 3D X-ray microscope at
the micro-CT laboratory of NIGP and analyzed in VG-
Studio MAX 3.0. Scanning parameters were as follows:
isotropic voxel size, 1.6106 μm; power, 3 W; accele ration
voltage, 40 kV; exposure time, 1.5 s; projections, 3001.
Images were further processed in Adobe Photoshop CC
to adjust brightness and contrast.
2.3. Molecular phylogenetic analysis
To test the robustness of the molecular phylogeny of Co-
rylophidae, we reanalyzed the data compiled by Robert-
son et al. (2013) with a site-heterogeneous model. Eight
genes were included, namely the nuclear genes 18S, 28S,
H3 and CAD, and the mitochondrial 12S, 16S, COI and
COII. All sequences were obtained from GenBank using
the Batch Entrez tool. The accession numbers were the
same as provided by Robertson et al. (2013). Sequence
alignment generally followed the procedure of Robertson
et al. (2013), though with slight modications. In brief,
the translated alignments of protein-coding genes were
done using MUSCLE (Edgar 2004) module in Geneious
4.8.4 with default parameters. The rRNA genes were
aligned using MAFFT 7.49 (Katoh and Standley 2013)
Q-INS-i option. The ambiguously aligned regions of 28S
(bp 2081–3196 in the alignment result) and CAD (bp
241–360 in the alignment result) were removed.
The site-heterogeneous mixture model CAT-GTR+G4
was run in PhyloBayes mpi 1.7 (Lartillot et al. 2009).
Two independent Markov chain Monte Carlo (MCMC)
chains were run until convergence (maxdi <0.3). Con-
vergence was assessed by using the bpcomp program to
generate output of the largest (maxdi) and mean (mean-
di) discrepancies observed across all bipartitions.
The tree was drawn with the online tool iTOL 5.7 (Le-
tunic and Bork 2019) and graphically edited with Adobe
Illustrator CC 2017.
2.4. Morphological phylogenetic
analysis
To evaluate the systematic placement of the new spe-
cies, a morphology-based phylogenetic analysis was
performed. The data matrix was mainly derived from a
previously published dataset (Ślipiński et al. 2009; Rob-
ertson et al. 2013).
The unconstrained parsimony analysis was performed
under implied weights using the program TNT 1.5 (Golo-
bo et al. 2008, 2016). Parsimony analyses achieve
highest accuracy under a moderate weighting scheme
(i.e., when concavity constants, K, are between 5 and 20)
(Golobo et al. 2018; Smith 2019). Therefore, the con-
cavity constant was set to 12 here, as suggested by Golo-
bo et al. (2018). Most parameters were set as default in
the “new technology search”, while the value for “nd
min. length” was changed from 1 to 100.
Since the morphology-based phylogeny of Corylophi-
dae was somewhat discordant with the molecular phy-
logeny, we additionally conducted a constrained analysis
Arthropod Systematics & Phylogeny 80, 2022, 411–422 413
(e.g., Slater 2013; Fikáček et al. 2020). For taxa with both
morphological and molecular data, their interrelationships
were xed according to the molecular tree. The fossil and
other extant taxa without molecular data were allowed to
move freely across the reference tree. The constrained par-
simony analysis was performed under implied weights (K
= 12) with R 4.1.0 (R Core Team 2021) and the R package
TreeSearch 1.0.1 (Smith 2021).
Character states were mapped onto the trees using un-
ambiguous optimization with WinClada 1.0 (Nixon 2002).
2.5. Abbreviations
The following abbreviations of institution are used:
CCGG Collection Carsten Gröhn, Glinde. GPIH
Geo logisch-Paläontologisches Institut und Museum der
Universität Hamburg. NIGP – Nanjing Institute of Geo-
logy and Palaeontology, Chinese Academy of Sciences.
The following abbreviations of morphological charac-
ters are used: BL – apparent body length in dorsal view;
BWbody width; ELelytral length; HLhead length;
HW – head width; PL – pronotal length; PW – pronotal
width. The following abbreviation is used in the phyloge-
netic analysis: PP – posterior probability.
3. Systematic paleontology
Order Coleoptera Linnaeus, 1758
Suborder Polyphaga Emery, 1886
Superfamily Coccinelloidea Latreille, 1807
Family Corylophidae LeConte, 1852
Tribe Xenostanini Li, Szawaryn & Cai
trib. nov.
http://zoobank.org/F879CF29-9E7A-4E63-8585-441F9A-
C242AA
Type genus. Xenostanus gen. nov.
Diagnosis. Body elongate (oval to circular in most Cory-
lophidae except for Foadiini, Aenigmaticini and Stanini).
Head partially exposed and visible from above (concealed
by produced pronotum in Peltinodini, Cleidostethini, Seri-
coderini, Parmulini, Corylophini, Teplinini and Rypobii-
ni). Antennae 10-segmented, with 3-segmented club (an-
tennae 8-, 9-, or 11-segmented, or with 5-segmented club
in some other tribes). Pronotum widest basally (narrowed
posteriorly in Aenigmaticini and some Foadiini); anterior
pronotal margin straight (produced or emarginate in vari-
ous corylophid groups except for Aenigmaticini and Stani-
ni). Prosternum in front of coxae as long as procoxal longitudi-
nal diameter (distinctly longer or shorter in various corylophid
groups except for Aenigmaticini, Stanini and Cleidostethini);
prosternal carinae absent (present in Periptycinae). Procoxal
cavities externally closed (open in Peltinodini). Elytra some-
what truncate apically, exposing pygidium (conjointly round-
ed and concealing all abdominal tergites in many Corylophi-
dae except for Foadiini, Aenigmaticini, Stanini, Sericoderini
and some Parmulini). Transverse mesoventral carina absent
(present in Stanini). Mesocoxal cavities laterally closed (lat-
erally open in Cleidostethini, Orthoperini and Teplinini).
Metaventrite with distinct postcoxal lines (metaventral post-
coxal lines absent in most Corylophidae except for Peltinodini
and Orthoperini). Tibiae with two small apical spurs. Abdomi-
nal ventrite 1 with strongly arcuate postcoxal lines (abdominal
postcoxal lines absent in most Corylophidae except for Foa-
diini, Peltinodini, and some Corylophini; such lines straight
in Foadiini).
Genus Xenostanus Li, Szawaryn & Cai gen.
nov.
http://zoobank.org/D85AF7C9-9BE5-4BBA-9F00-
E066B2D085B0
Type species. Xenostanus jiangkuni sp. nov.
Etymology. The generic name is composed of the Greek
xenos”, strange, and the generic name Stanus Ślipiński et
al. The name is masculine in gender.
Diagnosis. As for the tribe.
Xenostanus jiangkuni Li, Szawaryn & Cai
sp. nov.
http://zoobank.org/DF781A4B-9A46-460E-AD27-BDC09B-
CB1958
Figs 1–5, S1
Etymology. The species is named after Mr. Kun Jiang,
who kindly donated many fossils for our research.
Type materials. Holotype: NIGP177782. Two paratypes, GPIH no.
5058 (CCGG no. 11948), GPIH no. 5059 (CCGG no. 11105).
Type locality and horizon. Amber mine located near Noije
Bum Village, Tanai Township, Myitkyina District, Kachin
State, Myanmar; unnamed horizon, mid-Cretaceous, Upper
Albian to Lower Cenomanian.
Diagnosis. As for the tribe.
Description. Body elongate, widest at middle of elytra,
very weakly convex. Surface with hair-like setae. — Head
partially exposed and visible from above (Fig. 5F). Eyes
coarsely faceted, without interfacetal setae (Fig. 3B,C).
Frontoclypeal suture absent (Fig. 3B). Labrum free, trans-
Li et al.: Earlie fossil of Corylophidae
414
verse (Fig. 3B). Subantennal grooves absent. Antennae (Fig.
4C,D) with 10 antennomeres; scape distinctly longer and
wider than pedicel; antennomeres 3–7 small, subquadrate to
transverse; club (antennomeres 8–10) asymmetrical, as long
as antennomeres 3–7 combined. Mandibles short (Fig. 3A).
Maxillary palps (Fig. 3A) 3-segmented; apical palpomere
about twice as long as penultimate one, conical. Labial palps
(Fig. 3A) 2-segmented; apical palpomere about as long as
basal one. Ventral head surface seemingly with a pair of
parallel subgenal ridges (Figs 3A, 5E). Prothorax: Pro-
notal disc (Fig. 5F) widest at base; anterior margin straight;
lateral margins bordered in posterior part; posterior angles
pointed; posterior margin bisinuate. Prosternum (Figs 3A,
5E) in front of coxae about as long as longitudinal coxal
diameter, anteriorly not produced forward; prosternal cari-
nae absent; prosternal process broad, widened beyond front
coxae, meeting postcoxal hypomeral projections, truncate at
apex. Procoxal cavities externally closed, ovaloid, without
lateral slit (Fig. 5E). Meso- and metathorax: Scutellar
shield strongly transverse. Elytra covering entire abdomen
except for part of pygidium (Fig. 1A). Mesoventrite at,
without transverse carina (Figs 1B, 5A). Mesocoxal cavities
circular, outwardly closed (Figs 1B, 5A). Meso-metaventral
junction nearly straight (though with a small projection me-
dially). Metaventrite with distinct postcoxal lines (Figs 1B,
2B, 5A); discrimen visible in posterior third of metaventrite.
Metacoxae transverse, broadly separated. — Legs: Femora
attened. Tibiae simple, not strongly widened, apically with
small denticles; tibial spurs 2-2-2 (Fig. 3D). Tarsi 4-4-4 (Fig.
3D); tarsomeres 1 and 2 ventrally lobed; tarsomere 3 smaller
and simple; tarsomere 4 elongate, as long as 1–3 combined.
Pretarsal claws simple, with small basal angulation. Ab-
domen with six freely articulated ventrites. Ventrite 1 longer
than 2–4 combined, with strongly arcuate postcoxal lines
(Figs. 1B, 2B, 5A), anteriorly complete; intercoxal process
very broad and truncate.
Figure 1. General habitus of Xenostanus jiangkuni Li, Szawaryn & Cai gen. et sp. nov., holotype, NIGP177782, under incident
light. A Dorsal view. B Ventral view. Scale bars: 400 μm.
Arthropod Systematics & Phylogeny 80, 2022, 411–422 415
Measurements. NIGP177782: BL 1.42 mm, BW 0.63
mm, HL 0.27 mm, HW 0.31 mm, PL 0.34 mm, PW 0.51
mm, EL 0.96 mm. GPIH no. 5058: BL 1.88 mm, BW 0.74
mm. GPIH no. 5059: BL 1.30 mm, BW 0.62 mm
4. Results
4.1. Molecular phylogenetic analysis
The result under site-heterogeneous model (Fig. S2) was
well consistent with the result under site-homogeneous
model by Robertson et al. (2013). The monophyly of Cor-
ylophidae was strongly supported (PP = 1.00). Corylophi-
nae excluding Holopsis Broun (Peltinodini) was strongly
supported (PP = 1.00), while Corylophinae as a whole
was only moderately supported (PP = 0.83). All current-
ly recognized tribes (sensu Robertson et al. 2013) were
recovered as monophyletic groups. Foadiini (represented
by Foadia Pakaluk and Priamima Pakaluk & Lawrence)
was moderately supported (PP = 0.74), while all other
tribes were strongly supported (PP = 1.00).
4.2. Morphological phylogenetic
analysis
The result of unconstrained analysis (Fig. S3) is very sim-
ilar to that of Ślipiński et al. (2009), only with the posi-
tion of Sericoderini changed. Xenostanus was resolved as
Figure 2. General habitus of Xenostanus jiangkuni Li, Szawaryn & Cai gen. et sp. nov., holotype, NIGP177782, under confocal
microscopy. A Dorsal view. B Ventral view, with arrowheads indicating the metaventral and abdominal postcoxal lines. Scale bars:
400 μm.
Li et al.: Earlie fossil of Corylophidae
416
sister to the group consisting of Othoperini, Peltinodini,
Sericoderini, Corylophini, Teplinini and Rypobiini. The
tribes Aenigmaticini and Stanini were clustered together.
In the constrained analysis (Fig. 6), Aenigmaticini
and Stanini were only distantly related in the reference
tree. Partly aected by this topology, Xenostanus was re-
covered as the sister group of Stanini. Teplinini grouped
together with Rypobiini, and Cleidostethini grouped to-
gether with Orthoperini.
Figure 3. Details of Xenostanus jiangkuni Li, Szawaryn & Cai gen. et sp. nov., holotype, NIGP177782, under confocal microscopy.
A Head and prothorax, ventral view. B Head, dorsal view. C Head and prothorax, lateral view. D Abdominal base, ventral view.
Abbreviations: an, antenna; ey, compound eye; lb, labrum; lbp, labial palp; md, mandible; msf, mesofemur; msts, mesotarsus; mtf,
metafemur; mttb, metatibia; mtts, metatarsus; mtv, metaventrite; mxp, maxillary palp; pc, procoxa; pf, profemur; pn, pronotum; ps,
prosternum; pts, protarsus; v1–3, ventrites 1–3. Scale bars: 200 μm.
Arthropod Systematics & Phylogeny 80, 2022, 411–422 417
Figure 4. X-ray microtomographic reconstruction of Xenostanus jiangkuni Li, Szawaryn & Cai gen. et sp. nov., holotype,
NIGP177782. A Dorsal view. B Ventral view. C Lateral view. Scale bar: 400 μm.
Figure 5. X-ray microtomographic reconstruction of Xenostanus jiangkuni Li, Szawaryn & Cai gen. et sp. nov., holotype,
NIGP177782. A Ventral view, with legs removed. B Ventral view, rendered under “Sum along Ray” mode. C, D Antenna. E Head
and prothorax, ventral view. F Head and prothorax, dorsal view. Scale bar: 400 μm.
Li et al.: Earlie fossil of Corylophidae
418
5. Discussion
5.1. Sister group of Corylophidae
In the combined morphological and molecular data anal-
yses by Robertson et al. (2013), Coccinellidae was sister
to Corylophidae. However, in both phylogenies based
on molecular data alone (present study; Robertson et al.
2013), Anamorphidae (represented by Bystus Guérin-
Méneville and Symbiotes Redtenbacher) was resolved as
the sister group of Corylophidae. The sister-group rela-
tionship between Anamorphidae and Corylophidae have
been further supported by the large-scale phylogenomic
study (McKenna et al. 2019). Thus, the frequently advo-
cated combined analysis may not be an ideal solution to
utilize the information from both morphological and mo-
lecular data as it seems to be.
5.2. Phylogeny of Corylophidae
Compared with the site-homogeneous models, site-he-
terogeneous models account for the unequal rate of evo-
lution in sequences and have been proved to be more
insensitive to phylogenetic artifacts such as long branch
attraction (Lartillot et al. 2007; Pisani et al. 2015; Cai
et al. 2020, 2022). Site-heterogeneous models may
generate improved results even for analyses with lim-
ited gene fragments sampled (Li et al. 2021). For the
present study, the internal phylogeny of Corylophidae
generated with the site-heterogeneous model (Fig. S2)
was essentially identical to that generated with a site-ho-
mogeneous model by Robertson et al. (2013). Thus, the
current classication scheme of Corylophidae based on
this phylogeny is generally satisfactory, and could serve
as a framework for determining the position of the Xe-
nostanus fossil.
Rypobiini
Teplinini
Corylophini
Parmulini
Sericoderini
Xenostanini
Stanini
Cleidostethini
Orthoperini
Aenigmaticini
Foadiini
Peltinodini
Periptyctinae
Corylophinae
Corylophidae
Pharaxonotha
Hapalips
Holopsis
Clypastrea
Athrolips
Sericoderus
Aposericoderus
Corylophus
Teplinus
Orthoperus
Gloeosoma
Rypobius
Foadia
Priamima
Hyplathrinus
Ectinocephalus
Aenigmaticum
Stanus
Cleidostethus
Periptyctus
Pakalukodes
Weirus
Sticholotis
Coccidophilus
Bystus
Aphanocephalus
Notiophygus
111
3521
453522191612
19
2120
2220161412
15
32282119
1915
27
4645
271211
363512
45
4437313025
342826222119
171312
2612
2919
1811
47
11
10
19161411
15
38
27
352924
4133
423312
343332312923
0
0
0
4
64
2
642
9
654
4
84
1
73
0
31
2001120
0
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00
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112
12200
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011010
1
010010
20
01
112
0
211
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1101
0
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0
1
11011
10
1221012
Xenostanus gen. nov.
322622
010
Figure 6. Suggested placement of Xenostanus Li, Szawaryn & Cai gen. nov. within Corylophidae. Tree resulting from the mor-
phological parsimony analysis constrained by a molecular backbone tree. Black circles indicate nonhomoplasious changes; white
circles indicate homoplasious characters.
Arthropod Systematics & Phylogeny 80, 2022, 411–422 419
As discussed by Robertson et al. (2013), the uncon-
strained morphology-based phylogeny of Corylophidae
is largely inconsistent with the molecular one and there-
fore unreliable. Nevertheless, morphology may still pro-
vide some valuable information in cases where molecular
sequences are hard or impossible to obtain. The posi-
tions of Teplinini and Cleidostethini were not evaluated
by Robertson et al. (2013) due to the lack of molecular
data. In our constrained morphological analysis, Teplinini
was resolved as sister to Rypobiini, which is consistent
with the unconstrained analysis by Ślipiński et al. (2009).
However, the aberrant tribe Cleidostethini turned out to
be the sister group of Orthoperini, and they together were
sister to Aenigmaticini, while in the unconstrained anal-
ysis Cleidostethini was sister to the whole Corylophinae
except Foadiini, suggesting the requirement for further
analyses.
5.3. Placement of Xenostanus
Corylophidae is currently divided into two subfamilies,
Periptyctinae and Corylophinae (Ślipiński et al. 2009;
Robertson et al. 2013). Periptyctinae is composed of only
three genera, and was once placed in family Endomychi-
dae (Ślipiński et al. 2001, 2009). Xenostanus clearly does
not belong to Periptyctinae, based on its pedicel shorter
than scape (pedicel longer in Periptyctinae), absence of
prosternal carinae (prosternal carinae present in Perip-
tyctinae), and anterior pronotal margin unemarginated
(anterior pronotal margin deeply emarginate in Periptycti-
nae). Based on the morphological and molecular phylo-
genetic analyses, 11 tribes have been recognized within
Corylophinae (Ślipiński et al. 2009; Robertson et al.
2013). The unique character combination of Xenostanus
does not t well into any of the existing tribes. Xenosta-
nus has an elongate body shape. While most corylophids
have an oval to circular body, the tribes Foadiini, Aenig-
maticini and Stanini also have an elongate body, and are
sometimes referred to as latridiid-like taxa. Xenostanus
can be distinguished from Foadiini in the straight anterior
margin of pronotum (medially emarginate in Foadiini),
and from Aenigmaticini in the antennae with 10 antenno-
meres (with nine antennomeres in Aenigmaticini; Paka-
luk 1985) and the basally widest prothorax (posteriorly
narrowed in Aenigmaticini). The phylogenetic analysis
suggests a close relationship between Xenostanus and
Stanini (Fig. 6). Both taxa share a similar pronotal shape
(not constricted posteriorly). Nevertheless, Xenostanus
can also be distinguished from Stanini based on the an-
tennae (with 11 antennomeres in Stanini) and the absence
of transverse mesoventral carina (present in Stanini).
The postcoxal lines on metaventrite and abdominal
ventrite 1 are important diagnostic characters for Xe-
nostanus. These postcoxal lines are usually present in
Coccinellidae and some other related taxa (Ślipiński
and Tomaszewska 2010; Robertson et al. 2015). How-
ever, most corylophids do not possess such lines (e.g.,
Furukawa 2010: g. 4D). In extant Corylophidae, only
Holopsis (Peltinodini) is known to have metaventral and
abdominal postcoxal lines at the same time (e.g., Furu-
kawa 2012). Considering the basal position of Holopsis
within Corylophidae, the presence of postcoxal lines have
been suggested to be pleisiomorphic for it (Robertson et
al. 2013). By contrast, Xenostanus occupied a more de-
rived position in Corylophidae, and its postcoxal lines are
therefore likely gained secondarily.
Based on the results of phylogenetic analysis and
the above discussion on the morphological characters,
we suggest that Xenostanus should be placed in a new
tribe, Xenostanini trib. nov. The discovery of Xenosta-
nus greatly extends the earliest record of Corylophidae,
which implies this family had already been diversied by
mid-Cretaceous.
6. Data availability
The original confocal and micro-CT data are available in Zenodo repos-
itory (https://doi.org/10.5281/zenodo.6801815).
7. Competing interests
The authors have declared that no competing interests exist.
8. Acknowledgements
We are grateful to Adam Ślipiński for helpful discussion on the fossil,
Su-Ping Wu for technical help in micro-CT reconstruction, and Rong
Huang for technical help in confocal imaging. Carsten Gröhn (Glinde,
Germany) kindly provided the valuable paratype specimens used in this
study. Two anonymous reviewers provided valuable comments on the
manuscript. Financial support was provided by the Second Tibetan Pla-
teau Scientic Expedition and Research project (2019QZKK0706), the
Strategic Priority Research Program of the Chinese Academy of Sci-
ences (XDB26000000), and the National Natural Science Foundation
of China (41688103).
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Supplementary material 1
Figures S1–S3
Authors: Li Y-D, Zhang Y-B, Szawaryn K, Huang D-Y, Cai C-Y (2022)
Data type: .pdf
Explanation note: Figure S1. Xenostanus jiangkuni Li, Szawaryn & Cai gen. et sp. nov., paratypes, under incident
light. AD: GPIH no. 5059. E, F: GPIH no. 5058. Figure S2. Tree resulting from molecular Bayesian analysis
with the site-heterogeneous CAT-GTR+G4 model. — Figure S3. Tree resulting from unconstrained morphological
parsimony analysis.
Copyright notice: This dataset is made available under the Open Database License (http://opendatacommons.org/
licenses/odbl/1.0). The Open Database License (ODbL) is a license agreement intended to allow users to freely
share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source
and author(s) are credited.
Link: https://doi.org/asp.80.e81736.suppl1
Supplementary material 2
List of characters
Authors: Li Y-D, Zhang Y-B, Szawaryn K, Huang D-Y, Cai C-Y (2022)
Data type: .rtf
Explanation note: List of characters used in the phylogenetic analyses (adapted from Ślipiński et al. 2009; Robertson
et al. 2013).
Copyright notice: This dataset is made available under the Open Database License (http://opendatacommons.org/
licenses/odbl/1.0). The Open Database License (ODbL) is a license agreement intended to allow users to freely
share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source
and author(s) are credited.
Link: https://doi.org/asp.80.e81736.suppl2
Supplementary material 3
Morphological dataset
Authors: Li Y-D, Zhang Y-B, Szawaryn K, Huang D-Y, Cai C-Y (2022)
Data type: .tnt
Explanation note: Morphological dataset used for the analyses.
Copyright notice: This dataset is made available under the Open Database License (http://opendatacommons.org/
licenses/odbl/1.0). The Open Database License (ODbL) is a license agreement intended to allow users to freely
share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source
and author(s) are credited.
Link: https://doi.org/asp.80.e81736.suppl3
Li et al.: Earlie fossil of Corylophidae
422
Supplementary material 4
R code
Authors: Li Y-D, Zhang Y-B, Szawaryn K, Huang D-Y, Cai C-Y (2022)
Data type: .R
Explanation note: R code for the constrained parsimony analysis.
Copyright notice: This dataset is made available under the Open Database License (http://opendatacommons.org/
licenses/odbl/1.0). The Open Database License (ODbL) is a license agreement intended to allow users to freely
share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source
and author(s) are credited.
Link: https://doi.org/asp.80.e81736.suppl4
Supplementary material 5
Molecular dataset
Authors: Li Y-D, Zhang Y-B, Szawaryn K, Huang D-Y, Cai C-Y (2022)
Data type: .zip
Explanation note: Data for the molecular analysis and the output les.
Copyright notice: This dataset is made available under the Open Database License (http://opendatacommons.org/
licenses/odbl/1.0). The Open Database License (ODbL) is a license agreement intended to allow users to freely
share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source
and author(s) are credited.
Link: https://doi.org/asp.80.e81736.suppl5
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