ZooKeys 725: 37-47 (20 | 7) A peer-reviewed open-access journal
doi: 10.3897/zookeys.725.2 1040 RESEARCH ARTICLE $7Z00Ke y S

http:/ /Z00 keys -pen soft.net Launched to accelerate biodiversity research

Discovery of a most remarkable cave-specialized
trechine beetle from southern China
(Coleoptera, Carabidae, Trechinae)

Mingyi Tian'”, Sunbin Huang', Dianmei Wang!

| Department of Entomology, College of Agriculture, South China Agricultural University, Wushan,
Guangzhou, Guangdong, 510640, China

Corresponding author: Mingyi Tian (mytian@scau.edu.cn)

Academic editor: A. Casale | Received 17 September 2017 | Accepted 1 November 2017 | Published 29 December 2017
Attp://zoobank. org/078 BF7E 1-BAGA-409E-B045-2159 LF 7F82E4

Citation: Tian M, Huang S, Wang D (2017) Discovery of a most remarkable cave-specialized trechine beetle from
southern China (Coleoptera: Carabidae: Trechinae). ZooKeys 725: 37-47. https://doi.org/10.3897/zookeys.725.21040

Abstract

Xuedytes bellus Tian & Huang, gen. et sp. n. is described from a limestone cave in Du’an Karst of Guangxi,
a kingdom of cavernicolous trechine beetles in southern China. From a morphological point of view,
Xuedytes Tian & Huang, gen. n. seems to be the most extremely cave-adapted trechines in the world.
Superficially, it looks much like Giraffaphaenops Deuve, 2002 in general body shape, in particular the
structure of the prothorax, but simultaneously it is similar to Dongodytes (s. str.) Deuve, 1993, based on
elytral characters, including chaetotaxy. Hence the new genus seems to represent a lineage intermediate

between Giraffaphaenops and Dongodytes (s. str).

Keywords
aphaenopsian, Guangxi, ground beetle, troglobite

Introduction

The globe's largest and highly varied karst landscapes that blanket nearly the entire
area of southern China (Deharveng and Bedos 2012) are long known to host the
richest diversity of cave-dwelling trechine beetles in the world. To date, 48 genera of
cavernicolous trechines containing over 130 species have been recorded there (Deuve
and Tian 2016, Tian et al. 2016, Zhao and Tian 2016, Fang et al. 2017, Huang et al.

Copyright Mingyi Tian et al.. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0),
which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

38 Mingyi Tian et al. | ZooKeys 725: 37-47 (2017)

2017). Many of them are morphologically highly cave-adapted, such as Giraffaphae-
nops Deuve, 2002, Dongodytes Deuve, 1993, Uenotrechus Deuve & Tian, 1999, Pi-
losaphaenops Deuve & Tian, 2008, Sinaphaenops Uéno & Wang, 1991 and Shuang-
heaphaenops Vian, 2017. As the cave beetle fauna of China is still poorly-known, it is
hardly surprising that another highly peculiar species representing another new genus
has been revealed in the country (Tian 2017).

In early August 2017, a cave biological survey carried out in Duan Karst of northern
Guangxi, southern China led to the discovery of a very peculiar species belonging to the
subfamily Trechinae, family Carabidae. Moreover, it shows a number of most remarkable
troglomorphic features amongst subterranean trechines generally. Superficially, its strongly
elongated and slender body looks very much like that of a Giraffaphaenops species, especial-
ly due to the extremely elongated prothorax. However, Giraffaphaenops species are known
from the Leye-Tianlin karsts of northwestern Guangxi, about 200 km away from Du’an
Karst (Deuve 2002, Tian and Luo 2015). In contrast, the elytra in the new species are quite
similar to those observed in Dongodytes (s. str.) Deuve, 1993, yet being much more strongly
elongated. In addition, it has many other particular morphological characteristics, such
as: (1) Head comparatively short, but sufficiently long and aphaenopsian, bearing multi-
setiferous pores in frontal areas; (2) Right mandible edentate; (3) Prothorax extremely
elongated; (4) Lateral margins of pronotum visible in fore part from above, while long
erect setae on disc and two pairs of latero-marginal setae in middle portion present; and
(5) Elytra extremely elongated, smooth and glabrous, with striae completely obliterated.

Materials and methods

The beetles were collected in the cave using an aspirator, and kept in vials with 50%
ethanol before study, except for a specimen put in a vial with 95% ethanol for molecu-
lar analysis.

Techniques and terminology are the same as in Tian (2017).

Taxonomic treatment

Xuedytes Tian & Huang, gen. n.
http://zoobank.org/C8AACC92-F265-45CD-9F50-09DAB01LADFDO

Type species. Xuedytes bellus Tian & Huang, sp. n.

Generic characteristics. Highly modified aphaenopsian trechines, body shape, in
particular prothorax, similar to that in Giraffaphaenops, but elytra generally like in Don-
godytes (s. str.) (Fig. 1); large-sized, with body (especially prothorax and elytra) and ap-
pendages thin and extremely elongated, eyeless and unpigmented; fore body part (head
including mandibles, plus prothorax) much longer than, or as long as (excluding man-
dibles) elytra, respectively; body smooth; three pairs of frontal setiferous pores present

Discovery of a most remarkable cave-specialized trechine beetle from southern China... 39

on head; mandibles thin and elongated, feebly curved apically, longer than head width,
right mandible edentate; labial suture completely missing; mentum bisetose on either
side of tooth at base, base broadly concave; mental tooth simple, short and blunt at tip;
submentum 8-setose; ligula bisetose at apex (Fig. 2); antennae very long, antennomeres
10 and 11 extending beyond elytral apices. Prothorax similar to that of Giraffaphaenops,
wider than head, very strongly elongated, much longer than head including mandibles,
propleura distinctly tumid in basal 1/3, visible from above; pronotum barrel-shaped, thin
and distinctly elongated, lateral margins visible throughout from above, slightly narrower
than head; hind latero-marginal setae absent, but two long latero-marginal setae plus two
or three additional short setae present from middle to front. Elytra similar to those in
Dongodytes (s. str.), narrow anteriorly and dilated posteriorly, side margins narrowly bor-
dered throughout, shoulders lacking; striae virtually missing, only weakly traceable; two
dorsal and the pre-apical setiferous pores present, each with a very long seta; chaetotaxy
similar to that in Dongodytes (s. str.). Protibia smooth, without longitudinal sulcus; pro-
tarsomeres not modified in male. Ventrites VII bisetose apically in male, but quadrisetose
in female. Male genitalia moderately sclerotized, small, strongly curved ventrally in lat-
eral view, with a quite large and thin sagittal aileron; apical lobe wide and broad in dorsal
view; parameres much shorter than median lobe, yet well-developed.

Discussion. Xuedytes Tian & Huang, gen. n. is undoubtedly the most remarkable
cavernicolous trechine genera as regards the extremely elongated prothorax and elytra.
It may be considered as a lineage intermediate between Giraffaphaenops and Dongodytes
(Fig. 3). Superficially it resembles Giraffaphaenops because of the similarly thin and
strongly elongated body, especially the prothorax. Its elytra, however, are quite similar to
those of Dongodytes (s. str.). The most striking character states of Xuedytes are as follows:
(1) Prothorax much longer than head; (2) Elytra very narrow and strongly elongated; (3)
Three pairs of frontal pores present on head; and (4) Right mandibular tooth obsolete.

Although Xuedytes is similar to Giraffaphaenops, there are several important differ-
ences: (1) Prothorax and elytra much more strongly elongated in Xuedyzes than in Giraf-
Japhaenops; (2) Head subquadrate, slightly convex laterally, not contracted posteriad in
Xuedytes (vs. inversed triangular, with a well-marked neck constriction in Giraffaphae-
nops); (3) Entire lateral margins of pronotum visible from above in Xuedytes (vs. invisible
from above in front half in Giraffaphaenops); and (4) Two pairs of latero-marginal setae
present behind middle of pronotum in Xuedytes (vs. absent in Giraffaphaenops) (Fig. 3).

Apart from the differences in prothoracic features, Xuedytes is easily distinguished
from Dongodytes (s. str.) by the following characteristics: (1) Head thicker and broad-
er, not narrowed posteriad in Xuedytes (vs. thinner and evidently narrowed posteriad,
forming a long and distinct neck constriction in Dongodytes); (2) Three pairs of frontal
pores present in Xuedytes, instead of only one pair in Dongodytes; (3) Elytral striae com-
pletely obliterated in Xuedytes (vs. partially visible in Dongodytes) (Fig. 3).

Furthermore, differences between the new genus and both Giraffaphaenops and
Dongodytes are also evident regarding the structure of the male genitalia (Fig. 4). The
median lobe of the aedeagus is shorter in Xuedytes, but thicker, especially so at the base,
with a thinner, almost transparent sagittal aileron.

40 Mingyi Tian et al. / ZooKeys 725: 37-47 (2017)

> (<4

Etymology. “Xue + dytes’.

beetles are cavernicolous. Gender masculine.

Xue” in Chinese means “cave”, to indicate that the

Generic range. China (Guangxi Zhuang Autonomous Region).

Xuedytes bellus Tian & Huang, sp. n.
http://zoobank.org/13622878-92B3-43B7-B253-426CE076E37F
Figs 1-5

Holotype. Male, Cave II, southeastern Du’an Yao Autonomous County, Hechi Shi
(=Prefecture), northern Guangxi Zhuang Autonomous Region, southern China, VHI-
08-2017, leg. Mingyi Tian, Sunbin Huang, Dianmei Wang and Mengzhen Chen;
paratypes: 2 males and 1 female, IBID. All type material is deposited in the insect col-
lection of South China Agricultural University, Guangzhou.

Diagnosis. A large-sized, blind, cave-adapted trechine, remarkably modified mor-
phologically, with both prothorax and elytra highly elongated and slender so that body
five times longer than wide, antennae slightly shorter than body including mandibles,
extending beyond elytral apices; head, pronotum and base of elytra covered with sparse
erect setae. Habitus as in Figs 1 and 3.

Description. Length: 8.3—9.0 mm (from apex of right mandible to elytral apex) or
7.5-8.6 mm (from labrum to elytral apex); width: 1.4-1.5 mm.

Body yellowish brown, but antennae, palps and tarsi pale; strongly shining; head,
pronotum and base of elytra covered with rather long and sparse setae, other parts
of elytra glabrous, underside of fore body excluding pleurae, meso- and metasterna
pubescent, abdominal ventrites densely pubescent; microsculptural engraved meshes
transverse striate on head, pronotum and elytra; fore body very strongly elongated,
much longer than elytra, (HLm+PrL)/EL = 1.55-1.60.

Head oblong subquadrate, much longer than wide, HLm/HW = 3.02-3.03, HLI/
HW = 2.02—2.04; genae fairly well developed, broadly dilated on sides, widest at about
middle of head from neck to clypeal margin, gradually tapered posteriorly; frons and
vertex moderately convex, frontal furrows moderately defined, strongly diverging pos-
teriorly, ending level with middle frontal pores; clypeus transverse, 6-setose; labrum
transverse, frontal margin nearly truncate, 6-setose; three pairs of frontal setiferous
pores present; mentum and submentum completely fused, mentum bisetose on either
side of tooth at base, mental tooth short and blunt at apex, basal fovea broadly concave;
submentum 8-setose; palps thin and very slender, glabrous except for labial palpomere
2 which is bisetose on inner margin; 2" labial palpomere 1.40 times longer than 3";
3" maxillary palpomere 1.25 times longer than 4"; suborbital pore much closer to base
than to submentum (Fig. 2). Antennae thin and very long, 1* antennomere shortest
and stoutest, 4" longest, 11 longer than 10", length ratios of antennomere | to 11 as
1-001) 1236e3:070/3.55:1 25774 2814 2.527 2.10 t A94Y L657 194.

Prothorax (Fig. 3a) much longer than head including mandibles, PrL/HLm = 1.15-
1.17, PrL/HLI = 1.70-1.72, widest at about 1/5 off base, nearly 3 times as long as wide,

Discovery of a most remarkable cave-specialized trechine beetle from southern China... 4]

ir

Figure |. Habitus of Xuedytes bellus Tian & Huang, gen. et sp. n., holotype male.

42 Mingyi Tian et al. / ZooKeys 725: 37-47 (2017)

bn

\

Figure 2. Head (ventral) of Xuedytes bellus, a paratype female.

PrL/PrW = 2.94—2.95, slightly wider than head, PrW/HW = 1.18-1.19, evidently wider
than pronotum, PrW/PnW = 1.27—1.30. Pronotum very strongly elongated, tube-like in
front half which is narrow and nearly parallel-sided; convex at about basal 1/5 where the
widest point lies, then gently sinuate before hind angles which are obtuse and rectangular,
fore angles rounded; nearly four times longer than wide, PnL/PnW = 3.84, slightly narrow-
er than head, PnW/HW = 0.91-0.92, base slightly concave, wider than front, Pb W/PfW
= 1.27, front convex; lateral sides finely bordered throughout, base and front unbordered;

Discovery of a most remarkable cave-specialized trechine beetle from southern China... 43

Figure 3. Habitus of three highly modified aphaenopsian beetles (chaetotaxy indicated by white points)
a Xuedytes bellus, holotype male b Giraffaphaenops clarkei Deuve, 2002, male ¢ Dongodytes grandis Uéno,
1998, male.

44 Mingyi Tian et al. / ZooKeys 725: 37-47 (2017)

Figure 4. Male genitalia of three highly modified aphaenopsian beetles, median lobe and parameres in
lateral, and apical lobe in dorsal views, respectively a, b Xuedytes bellus c,d Giraffaphaenops yangi Tian &
Luo, 2015 e Dongodytes grandis Uéno, 1998.

Discovery of a most remarkable cave-specialized trechine beetle from southern China... 45

Figure 5. Cave I, southeastern Du’an, the type locality of Xuedytes bellus, and sympatric cave animals a,

b cave environs and opening € a chamber in the cave where the beetles were collected d a running beetle

in cave e, f cave spiders g, h cave millipedes i a cave woodlouse j a cave cricket.

46 Mingyi Tian et al. / ZooKeys 725: 37-47 (2017)

basal latero-marginal setae absent, two latero-marginal setae present in about middle por-
tion, with three or four additional short setae in fore part; disc strongly convex in front and
moderately convex in basal half, deeply concave a little before middle; median line clear, but
shallow, basal transverse impression well-marked, short; scutellum fairly large.

Elytra (Fig. 3a) very strongly elongated ovate, much longer than wide, EL/EW = 2.46;
longer than prothorax, EL/PrL = 1.58—1.59, almost twice as wide as prothorax, EW/PrW
= 1.90-1.91; distinctly dilated posteriorly, widest at about 3/5 of elytra off base, lateral
sides smooth, not ciliate, finely bordered throughout, marginal gutters well-marked; disc
distinctly convex, but evidently concave near base; striae virtually missing, yet more or less
traceable, intervals moderately convex. Chaetotaxy (Fig. 3a): dorsal pores with stout and
long setae, two dorsal setiferous pores present on 3” stria at about 1/3 and 3/5 of elytra off
base, respectively; pre-apical pore at about apical 1/6 of elytra, much closer to elytral suture
than to apical margin; basal pore located between scutellum and marginal gutter; marginal
umbilicate pores not aggregated, pores 1-3 and 10 near marginal gutter, other pores dis-
tant from gutter; humeral groups with pores 1 and 4 widely isolated, 2 and 3 close to each
other, distance from pore 4 to 3 subequal to 5; middle group closely spaced, distance of
pore 5 and 4 subequal to that of pore 5 and 6; apical group composed of four pores.

Legs slender and long, bearing short pubescence; fore and middle femora sparsely
setose; fore tibia smooth, with neither a longitudinal furrow nor a sulcus; 1“ tarsomere
shorter than, slightly longer than, and much longer than 2"*—4" tarsomeres combined
in fore, middle, and hind legs, respectively.

Male genitalia (Fig. 4a, b). Aedeagus quite small and short, distinctly curved ventrally
in middle portion in lateral view, then broad at apex; inner sac with a fairly large copulatory
piece, the latter about 1/3 as long as median lobe; base quite large, open ventrally, with a
hyaline sagittal aileron; in dorsal view, apical lobe fairly stout, slightly sinuate on right side,
rounded at apex. Parameres short and quite elongated, each bearing four long apical setae.

Etymology. “Be//us”, in Latin meaning “beautiful”, to refer to this beautiful aphae-
nopsian beetle.

Distribution. China (Guangxi: Du’an). Known only from Cave II.

This cave maintains a natural condition, opening on a small hill on the northern
bank of the Hongshui River. The entrance is surrounded by dense bushes and not readily
accessible (Fig. 5a, b). The total length of the cave is still unknown, but said to be about
200 m, according to local people. It is sufficiently wet inside the gallery and is good for
cave fauna. The beetles were found running on walls and stalactites (Fig. 5c, d), sympatric

with spiders (Fig. 5e, f), millipedes (Fig. 5g, h), woodlice (Fig. 5i) and crickets (Fig. 5j).

Acknowledgements

We are most grateful to Dr. Thierry Deuve (National Museum of Natural History, Par-
is) for his comments and suggestions that proved to be helpful in improving an early
draft of this manuscript. Our particular thanks go to Dr. Sergei Golovatch (Russian
Academy of Sciences, Moscow) for checking the English. This study is sponsored by

Discovery of a most remarkable cave-specialized trechine beetle from southern China... 47

the Nanjing Institute of Environmental Sciences, Ministry of Environmental Protec-
tion, through a biodiversity conservation project which focused on cave biodiversity,
and a project of the Specialized Research Fund for the Doctoral Program of Higher
Education of China (Grant no. 20134404110026).

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