Contributions to the knowledge of subterranean trechine beetles in southern China’s karsts: five new genera (Insecta, Coleoptera, Carabidae, Trechinae)

Abstract Recent discoveries reveal that southern China’s karsts hold the most diverse and morphologically modified subterranean trechine beetles in the world, albeit the first troglobitic blind beetle was only reported in the early 1990’s. In total, 110 species belonging to 43 genera of cavernicolous trechines have hitherto been recorded from the karsts of southern China, including the following five new genera proposed below: Shiqianaphaenops Tian, gen. n., to contain two species: Shiqianaphaenops majusculus (Uéno, 1999) (= Shenaphaenops majusculus Uéno, 1999, comb. n.), the type species from Cave Feng Dong, Shiqian, Guizhou, and Shiqianaphaenops cursor (Uéno, 1999) (= Shenaphaenops cursor Uéno, 1999, comb. n.), from Cave Shenxian Dong, Shiqian, Guizhou; and the monotypic Dianotrechus Tian, gen. n. (the type species: Dianotrechus gueorguievi Tian, sp. n., from Cave Dashi Dong, Kunming, Yunnan), Tianeotrechus Tian & Tang, gen. n. (the type species: Tianeotrechus trisetosus Tian & Tang, sp. n., from Cave Bahao Dong, Tian’e County, Guangxi), Huoyanodytes Tian & Huang, gen. n. (the type species: Huoyanodytes tujiaphilus Tian & Huang, sp. n., from Longshan, Hunan) and Wanhuaphaenops Tian & Wang, gen. n. (the type species: Wanhuaphaenops zhangi Tian & Wang, sp. n., from Cave Songjia Dong, Chenzhou, Hunan).


Introduction
and Wang 1991, Magrini et al. 1997, Uéno and Ran 1998, Uéno 2002, Deuve and Tian 2014; Sinotroglodytes Deuve, 1996: two species, troglobitic, in northwestern most Hunan (Deuve 1996, Uéno 2009); Superbotrechus Deuve & Tian, 2009: a single species, troglobitic, in western Hubei (Deuve and Tian 2009); Toshiaphaenops Uéno, 1999: two species, troglobitic, from northwestern Hunan and western Hubei (Uéno 1999a); Trechiotes Jeannel, 1954: three species, troglophilous, in Guizhou and Guangxi , Deuve 1995, Uéno 2007; Uenotrechus Deuve & Tian, 1999: one species, highly modified, troglobitic, in southern Guizhou and northern Guangxi Tian 2010); Wulongoblemus Uéno, 2007: one species, troglobitic, in western Zhejiang (Uéno 2007); Yanzaphaenops Uéno, 2010: a single species, highly modified, troglobitic, in Shennongjia, western Hubei (Uéno 2005b(Uéno , 2010; Yunotrechus : a single troglobitic species from southernmost Yunnan ; Zhijinaphaenops Uéno & Ran, 2002: five species, troglobitic, in western and central Guizhou (Uéno and Ran 2002;Deuve and Tian 2015). Uéno (1999a) set up the genus Shenaphaenops based on a single female collected from a limestone cave called Shen Dong (actually, the complete name of the cave is Shendong Migong) in Shuicheng County, northwestern Guizhou Province. Later, he found two new species from caves in Shiqian County, northeastern Guizhou and described them in Shenaphaenops, even though he realized that both two counties lay very far from each other, and the beetles found in Shiqian showed some peculiar features, in particular, a dilated protarsomere 1 in both sexes, a character never seen in other trechines (Uéno 1999b). We visited the type localities in both counties twice in 2014 and 2015, respectively, and successfully collected a male of Shenaphaenops humeralis Uéno, 1999, the type species, as well as an abundant material of S. majusculus Uéno, 1999. The newly collected samples provided enough evidence to show that both of these species are sufficiently different in many characters of generic importance to warrant the placement of the two known species from Shiqian into a new genus, not Shenaphaenops.
Thanks to Dr. Borislav V. Gueorguiev (National Museum of Natural History, Sofia, Bulgaria), we received a very peculiar trechine for study and as a gift. This female specimen was collected in a limestone cave called Dashi Dong in a suburb of Kunming, the capital city of Yunnan Province in autumn 2011 during a China-Bulgaria joint cave exploration in Yunnan organized by Prof. Fan Zhang (Yunnan Institute of Geography, Yunnan University). This interesting anophthalmic beetle appears to be new both at the specific and generic levels.
Among the new findings of cave-dwelling trechines during our cave surveys in Guangxi in July and August 2015, perhaps the most interesting was an unexpected species collected in Cave Bahao Dong, Tian'e County. It is sympatric with Dongodytes giraffa Uéno, 2005, an extremely troglomorphic beetle, but shows very unusual morphological characters not seen in any other cavernicolous trechines known in China, such as the right mandible being quadridentate, the pronotal lateral borders invisible from above and the elytra with three dorsal pores.
In July 2014, a single female trechine was discovered in the famous Huoyan Karst, Longshan County, northwesternmost Hunan Province. It lives there together with Cathaiaphaenops, Sinotroglodytes, Cimmeritodes and Toshiaphaenops species. However, this semi-aphaenopsian beetle is very different from the other sympatric Trechini, with several peculiar characters such as a very long and tube-like head, strongly dilated femora, very convex pronotum and elytra, and a strange elytral chaetotaxy, in which the humeral group of marginal umbilicate series is composed of five, not four, pores.
In late August 2015, we were invited to undertake a cave biodiversity survey in the Wanhuayan cave system, southern Hunan, as part of the cave exploration activities headed by Prof. Yuanhai Zhang (Institute of Karst Geology, Chinese Academy of Geological Sciences, Guilin). Several specimens of a blind trechine species were collected. This peculiar troglobitic species is probably related to Shenaphaenops or even the Sinaphaenops complex, but with many different characteristics of generic importance.
In order to properly assess the above trechine species, five new genera are established below, including the proposal of two new combinations for both Shiqian species formerly treated in Shenaphaenops, and the description of four new species forming four monotypic genera from limestone caves in Yunnan, Guangxi and Hunan, respectively.

Material and methods
The beetle specimens were collected by using an aspirator inside the cave, and kept in 55% ethanol before study. Dissections and observations were made under a Leica S8AP0 microscope. Dissected genital pieces, including the median lobe and parameres of the aedeagus, were glued onto small transparent plastic plates and pinned under the specimen they belonged to. Habitus pictures were taken by means of a Keyence VHX-5000 digital microscope. Genital pictures were taken using a Canon EOS 40D camera connected to a Zeiss AX10 microscope, and then stacked and processed by means of Adobe Photoshop CS5 software. Distribution maps created using Mapinfo software.
The length of the body was measured from the apex of the right mandible (in open position) to the elytral apex; the width of the body was taken as the maximum width of the elytra.
Abbreviations of other measurements used in the text are as follows: HLm length of head including mandibles, from apex of right mandible to occipital suture; HLl length of head excluding mandibles, from front of labrum to occipital suture; HW maximum width of head;

PrL
length of prothorax, along the median line; PnL length of pronotum, as above; PrW maximum width of prothorax; PnW maximum width of pronotum; PfW width of pronotum at front; PbW width of pronotum at base; EL length of elytra, from base of scutellum to elytral apex; EW maximum width of combined elytra.
Generic characteristics. Medium-sized aphaenopsian trechines, yet not too highly modified morphologically; eyeless, unpigmented and apterous; body slender and elongate, with slender and long appendages; covered with sparse pubescence, hairs being much longer on head and pronotum than on elytra; head elongate, longer than prothorax, much longer than wide; frontal furrows short, with two pairs of supraorbital pores; right mandible tridentate; labial suture clear; mentum 4-setose, tooth simple and short, blunt at apex; submentum 9-setose; antennae long, nearly extending to elytral apex; prothorax longer than wide, propleura visible from above; pronotum elongate, longer than wide, widest near front; only anterior pairs of lateromarginal setae; elytra elongate-ovate, strongly convex, shoulders distinct and rounded, lateral margins ciliated throughout; striae faintly impressed; two dorsal and the pre-apical pores present on each elytron; humeral group of marginal umbilicate pores not aggregated; protibia without longitudinal groove externally; 1 st protarsomere in both sexes widened and angularly produced externally, with a row of comb-like setae on ventral side; 1 st and 2 nd protarsomeres modified in male; ventrite VII with two pairs of setae in both sexes.
Remarks. Uéno (1999) hesitantly treated the two trechine species found in Shiqian County, eastern Guizhou as members of the genus Shenaphaenops Uéno, 1999, which had been set up based on a single female collected in Shuicheng County, northwestern Guizhou. However, he realized some striking differences and the geographical gap between the Shiqian species and the type species S. humeralis Uéno, 1999. Apart from the somewhat similar general body configurations in both Shiqianaphaenops gen. n. (Fig. 1) and Shenaphaenops (Fig. 2), many character states of generic importance are  (Uéno, 1999), comb. n., male Scale bar: 2.0 mm. Uéno, 1999, male Scale bar: 2.0 mm. different, such as: (1) 1 st protarsomere in both sexes widened apically and distinctly produced externally, covered with a ctenidium structure ventrally in Shiqianaphaenops which, amongst trechines, is only found in this genus; (2) right mandible tridentate in Shiqianaphaenops, versus bidentate in Shenaphaenops; (3) labial suture clear in Shiqianaphaenops, but completely missing in Shenaphaenops; (4) ventrite VII in male bisetose in Shiqianaphaenops, versus 4-setose in Shenaphaenops; (5) in male, both 1 st and 2 nd protarsomeres modified in Shiqianaphaenops, versus only 1 st protarsomere being modified in Shenaphaenops; (6) pubescence weaker and sparser, hairs much longer on head and pronotum than on elytra in Shiqianaphaenops, versus generally denser and hairs being of same length in Shenaphaenops; (7) base of pronotum much narrower than front in Shiqianaphaenops, versus only slightly narrower in Shenaphaenops; (8) elytra broader, with humeral angles rounded in Shiqianaphaenops (Fig. 3A), versus more slender, with humeral angles distinctly angular in Shenaphaenops (Fig. 3B); (9) marginal sides of elytra ciliate throughout, versus smooth in Shenaphaenops; (10) in Shiqianaphaenops, median lobe of aedeagus stout and thick, broadly rounded dorsally, basal part comparatively small, with an indistinct sagittal aileron, inner sac armed with a very large copulatory piece; apical lobe contracted at apex, roundly blunt in lateral view, but pointed in dorsal view; parameres thin, much shorter than median lobe, each bearing three long setae at apex (Fig. 4A, B). In contrast, median lobe of aedeagus in Shenaphaenops slender and thin, gently expanded dorsally, basal part comparatively large, with a small but distinct sagittal aileron; apical lobe indistinctly contracted at apex, obtuse in lateral view, broad in dorsal view; inner sac armed with a large copulatory piece; parameres shorter than median lobe, left one slightly longer than right one, each bearing two long setae at apex (Fig. 4C, D).

Figure 2. Habitus of Shenaphaenops humeralis
Etymology. Shiqian+Aphaenops, to indicate that both known members of this genus occur in Shiqian County, eastern Guizhou Province. Gender masculine.
Remarks. The most striking peculiarities of this new genus lie in the conformation of the pronotum and the chaetotaxal pattern on the elytra, especially the middle group of umbilicate pores, in which the 5 th pore is much closer to the 4 th than to the 6 th . Dianotrechus gen. n. seems to be particularly close to Shilinotrechus Uéno, 2003, an anophthalmic trechine genus also recorded from eastern Yunnan, but the former genus differs from the latter by the following character states: small-sized (versus mediumsized in Shilinotrechus); right mandible bidentate (versus tridentate in Shilinotrechus); body shape nearly parallel-sided (versus fusiform in Shilinotrechus); head of anophthalmic type (versus aphaenopsian type in Shilinotrechus); ventrite VII with three pairs Figure 6. Cave Feng Dong, type locality of Shiqianaphaenops majusculus (Uéno, 1999), comb. n. A entrance B cave chamber, to show where the beetles were collected C a wandering individual in cave. of setae in female (versus two pairs in Shilinotrechus). Some more differences are also evident in the conformation of the pronotum and elytra, as well as the chaetotaxy pattern of the marginal umbilicate series.
Compared to Cimmeritodes Deuve, 1996, a small-sized trechine genus originally reported from the Huoyan Karst of Longshan County, northwestern Hunan Province, but also occurring in Zhejiang (Deuve and Tian 2015), Dianotrechus gen. n. is easily distinguished by the bidentate right mandible (versus tridentate in Cimmeritodes), the quadrate pronotum (versus cordate in Cimmeritodes), the chaetotaxy pattern of the marginal umbilicate series, in which the 5 th is more distant from the 6 th than from the 4 th (reverse in Cimmeritodes), and ventrite VII has three pairs of setae in the female (two pairs in Cimmeritodes).
Etymology. Dian + Trechus, "Dian" is a short name for Yunnan Province in Chinese. The name of the new genus reflects the occurrence of this cavernicolous trechine in Yunnan. Gender masculine.

Diagnosis.
A small, stout, yellowish brown beetle which is densely pubescent, with short fore body and appendages, convex head, not tumid propleura which invisible from above, rather flat elytra and coarsely punctate elytral striae.
Description. Length: 3.1 mm (including mandibles), width: 0.9 mm. Habitus as in Fig. 7 Whole body yellowish brown, with palps pale; head and pronotum shiny, elytra dim; frons and vertex glabrous, genae with several short hairs, pronotum with a few fine setae, whole elytra covered with erect setae, these being as long as those on genae; underside generally glabrous, smooth and polished, but a few short hairs present on ventrites II and IV, and in lateral areas of prosternum; microsculptural meshes vanishing on head and pronotum, densely and moderately engraved on elytra. Fore part of body much shorter than elytra, EL/(HLm+PnL) = 1.39.
Head short and stout, much longer than wide (including mandibles), HLm/HW = 1.44, or as long as wide (excluding mandibles), genae broadly convex, frons and vertex moderately convex, frontal furrows entire, strongly divergent backwards; both supra-orbital pores closely located, posterior ones almost on frontal furrows, distance between anterior and posterior pores shorter than that between supra-orbital furrows at the closest point, neck short and broad; clypeus 4-setose, labrum transverse, nearly straight at frontal margin, 6-setose; mandibles rather short; labial suture missing; mentum 4-setose (two laterally and two at base of mental tooth); mentum tooth simple, very short, broad at apex; basal emargination wide and rather deep; ligula small and short, adnated to paraglossae, widened at apex, 6-setose; palps stout and short, penultimate joints much stouter than apical ones; 3 rd maxillary palpomere slightly longer than 4 th , labial palpomere 2 nd distinctly longer than 3 rd , bisetose at inner margin, with two additional setae in outer apical parts; 3 rd maxillary palpomere with two tiny setae near apex; suborbital pores present, located in median portion of ventral genae, lying far from base of head; antennae short and stout, wholly pubescent, 1 st antennomere stouter than others, 1 st , 2 nd and 4 th -10 th subequal in length, 3 rd slightly longer than 2 nd , but slightly shorter than 11 th . Prothorax: propleura not tumid, invisible from above; pronotum transverse, PnL/ PnW = 0.84, wider than head, PnW/HW = 1.27, much shorter than head (including mandibles), HLm/PnL = 1.44, or as long as head (excluding mandibles); disc moderately convex; widest at about middle where lateral sides slightly expanded but remaining nearly parallel-sided, reflexed near hind angles; fore lateromarginal seta located at a little before middle, basal one a little before hind angle; fore angles rounded, basal ones rectangular and pointed; base as wide as front; front almost straight, base nearly straight medially, obtusely sinuate near hind angles; median line fine and well-defined, reaching front margin, but ending before basal transverse impression, the latter being distinctly marked and connected to basal foveae; front transverse impression unclear. Scutellum small and short.
Elytra elongate, slender, moderately convex, wider than pronotum, almost twice as long as wide, EL/EW =1.93, widest at about middle of elytra, gently narrowed towards base and subapex; base wide, shoulders rounded, prehumeral angles missing; apex of each elytron rounded; disc moderately convex, striae coarsely punctate, intervals slightly convex; 1 st -4 th striae and apical striae well-marked, 1 st -3 rd striae complete, 4 th finished at level before median dorsal pore; other striae wanting; basal pore present, lying near basal margin and on side of scutellum; both dorsal pores located on 4 th intervals, at about basal third and a little behind the middle of elytra, respectively, pre-apical pore located at apical fusion of 2 nd and 3 rd striae, level to ending point of apical stria, about twice as far from apex as from suture; marginal umbilicate series with 1 st , 2 nd , 6 th and apical pores close to marginal gutter, 2 nd -4 th pores equidistant, but 1 st more isolated; 5 th pore widely removed away from 6 th and closer to 4 th pore.
Legs moderately long, covered with dense and short hairs; protarsi short, 1 st tarsomere not distinctly wider than others, longer than 2 nd and 3 rd combined, but shorter than 2 nd -4 th combined; meso-and metatarsi longer, 1 st tarsomere as long as 2 nd -4 th combined, respectively. Ventrites IV-VI each with a pair of paramedian setae, ventrite VII in female with three pairs of setae.
Male: Unknown. Etymology. In honour of Dr. Borislav V. Guéorguiev (National Museum of Natural History, Sofia, Bulgaria), an expert in Carabidae.
Distribution. China (Yunnan) (Fig. 5a). Known only from the limestone Cave Dashi Dong in a western suburb of Kunming City (Fig. 8A-C).
Dashi Dong is located more than 1 km away from Ermu Village, Xianjie Zhen, Anning, Kunming. The opening of this cave is 27 m wide and 17 m high. Its total length is 1394 m and the total depth is 39.30 m. The temperature in the dark parts is 21 °C. The unique beetle was collected in the dark area. In order to find more specimens of this interesting beetle, we visited this cave three times in July 2014, July 2015 and August 2015, but of no avail. Diagnosis. Medium-sized cave beetles, with typical aphaenopsian head, reduced frontal furrows, quadridentate right mandible, evident labial suture, bisetose mentum, robust pronotum, invisible propleura from above though which is tumid, and strongly covex elytra which have three pairs of dorsal setiferious pores.

Tianeotrechus
Generic characteristics. Medium-sized and semi-aphaenopsian trechines, eyeless, unpigmented and apterous; head evidently aphaenopsian, with incomplete frontal furrows and a somewhat elongated head, with two pairs of supra-orbital pores; mandibles developed, right mandible quadridentate, molar and retinacular teeth more developed than premolar tooth which is bifid (Fig. 9A); mentum and submentum well separated by labial suture; mentum bisetose, distinctly concave, mental tooth short and thick, bifid apically; submentum provided with a row of seven setae, median one minute and much shorter than others; antennae fairly short, reaching a little beyond middle of elytra; pronotum robust, longer than wide, sides expanded at apical third, making lateral suture invisible from above; posterior lateromarginal setae absent; elytra strongly convex, nearly as long as fore body (including mandibles), humeral shoulders roundly angulate, lateral sides smooth; striae reduced but more or less traceable; three dorsal and the pre-apical setae present; marginal umbilicate series not aggregate, only 2 nd pore close to marginal gutter; 1 st pore of humeral group shifted backward and about level Figure 9. Habitus of Tianeotrechus trisetosus Tian & Tang, gen. n., sp. n., holotype, male Scale bar: 2.0 mm, A enlarged right mandible to show the quadrisetose teeth to 5 th stria, a little behind 2 nd ; 4 th distant from 3 rd ; both pores of middle group lying close to each other; legs moderate for cave trechines, tibiae without longitudinal furrows externally; protarsi in male not modified; ventrite VII bisetose in male, 4-setose in female; male genitalia minute, well-sclerotized, moderately curved in middle part, apex slightly raised and pointed in lateral view; basal part quite large, sagittal aileron present; inner sac armed with a thin and scale-covered copulatory piece; parameres large but short, each bearing three long setae at apex.
Remarks. It is not easy to determine the taxonomic position of this new genus. Several generically important characters of Tianeotrechus gen. n. do not exist in the other genera of Chinese Trechini: a quadridentate right mandible, invisible pronotal lateral borders and the presence of three dorsal pores on each elytron. We hope more discoveries in the near future will be able to shed additional light to clarify this problem.
Etymology. Tian'e + Trechus, in reference to the provenance of the type species from Tian'e County. Gender masculine.

Diagnosis.
A medium-sized trechine, with shiny and robust body, moderated appendages, convex pronotum and elytra, and elongated elytra which have round shoulders and reduced striae.
Body brownish red, with palps, antennae and tarsi pale; frons, vertex and underside of head, pronotum, inner part of elytra glabrous, propleura and prosternum glabrous; genae, lateral parts of elytra, meso-and metasterna, and visible ventrites clothed with short pubescence; legs densely pubescent, covered with longer setae; microsculptural engraved meshes moderately transverse on head, strongly striate on pronotum and elytra.
Head elongate, much longer than wide, HLm/HW = 1.78-1.80 (mean 1.79), HLl/HW = 1.29-1.34 (mean 1.32); frons and vertex moderately convex; frontal furrows fairly long but incomplete, nearly parallel-sided, albeit slightly divergent posteriad, ending near neck constriction; genae barely expanded laterally, both sides held almost parallel; anterior and posterior supra-orbital pores located in the middle of genae and near neck constriction, respectively, distance between anterior and posterior pores much less than that between anterior pores; clypeus 4-setose, labrum transverse, widely but shallowly emarginated at front margin, 6-setose; mandibles distinctly curved at apex; palps thin and moderately long, 3 rd and 4 th maxillary pal- pomeres, and 3 rd labial palpomere glabrous, 2 nd labial palpomere 4-setose; penultimate palpomere evidently longer than apical one of labium, slightly longer in maxilla; suborbital pores on ventral side of genae, located closer to submentum than to base of head; antennae extending to about apical 3/4 of elytra, pubescent from 2 nd in apical half; 1 st antennomere stout and bearing several setae, slightly shorter than 2 nd ; 3 rd 1.6 times longer than 2 nd ; 3 rd , 4 th and 5 th subequal in length, then gradually shortened from 6 th to 10 th ; 11 th as long as 9 th .
Elytra elongate ovate, much longer than wide, EL/EW = 1.72-1.75 (mean 1.74); as long as head (including mandibles) plus pronotum; much wider than pronotum, EW/PnW = 1.80-1.88 (mean 1.83); widest at about 3/7 ths from base; prehumeral part short, humeral angles rounded; lateral sides smooth and well-beaded, ciliated throughout; disc strongly convex except for a small area near base just behind scutellum, the latter being somewhat depressed; striae more or less obliterated but traceable, intervals slightly convex; base not bordered; basal pores on either side of scutellum, close to basal margin; three dorsal pores present on 3 rd stria, located at about 1/6 th , 2/5 ths , 2/3 rds and 5/6 ths of elytra from base, respectively; pre-apical pore lying at about 5/6 ths of elytra, at site of junction of 2 nd , 3 rd and 4 th striae, much closer to elytral suture than to apical margin; humeral group of marginal umbilicate pores not aggregated, 1 st , 2 nd and 3 rd pores forming an equilateral triangle, 4 th widely distant from other three, 2 nd close to, 4 th far from, marginal gutter; middle group located behind middle of elytra, close to each other, distant from marginal gutter; apical pore minute, placed near elytral apex.
Legs moderately long, tibiae not longitudinally furrowed, hind tibia as long as elytral width; protarsi short; 1 st tarsomere shorter than, or subequal to, or longer than 2 nd -4 th tarsomeres combined in pro-, meso-and metatarsi, respectively; 4 th tarsomere wider than long in fore leg, as long as wide in middle leg, and evidently longer than wide in hind leg. Ventrites IV-VII each with one pair of setae.
Male genitalia (Fig. 10A, B): The median lobe of aedeagus well-sclerotized, small and slender, moderately curved ventrally in middle part, pointed at apex in lateral view; in dorsal view, apical lobe roundly broad at apex, nearly parallel-sided; base widely opening, with a large and thick sagittal aileron; parameres broad, much shorter than median lobe.
Etymology. To refer to the presence of three dorsal pores on elytron. Distribution. China (Guangxi) (Fig. 5d). Known so far from the limestone Cave Bahao Dong, southern Tian'e County (Fig. 11A).
The cave opens below a hill, surrounded by trees and bushes and is invisible from outside. The entrance is large, but the length remains unknown. It is deep and hardly accessible, accumulated by random ripraps; it takes the cavers about an hour to reach the underground river which runs through the deepest part of the cave. All of the type series were collected under stone in twilight and transition zones, thirty to fifty meters from the entrance. It is sympatric with Dongodytes giraffa Uéno, 2005 (Fig. 11B, C). Diagnosis. Large-sized, semi-aphaenopsian beetles, with elongated and tube-like head, long fore body, bidentate right mandible, bisetose mentum, well defined labial suture, tubiform and tumid prothorax, five pores in the humeral group of the marginal umbilicate series and disappeared elytral striae.
Remarks. Again, the affinities of Huoyanodytes gen. n. are bound to remain obscure. Its tube-like head, the more dilated subapically femora, the very convex pronotum and elytra, and the peculiar elytral chaetotaxy are the apomorphies that make it unrelated to any other genera so far known in China. It must be pointed out that it is the first example in a trechine beetle which humeral group of umbilicate marginal pores as composed of five pores, instead of four.

Diagnosis.
A large cavernicolous beetle, with light dark brown fore body, light brown elytra, tubiform head and prothorax, strongly convex elytra and 4-setose on each of visible abdominal ventrites.
Head evenly slender, much longer than wide, HLm/HW = 2.90, or HLl/HW = 2.08, genae well-developed and elongated, making head tube-like, nearly parallelsided; frons, vertex and genae moderately convex; frontal furrows wide and deep, but short, ending at about middle of head from labrum, almost parallel to each other; anterior supra-orbital pores located at about basal 4/7 th of head, lateral to frontal furrow and a little before its ending points, posterior ones located at about basal 1/5 th of head excluding mandibles; distance between anterior pores as great as that between anterior and posterior pores of each side; clypeus 8-setose; labrum strongly transverse, straight at frontal margin, 6-setose; mandibles long and thin, gently incurved in apical half and distinctly unciform at apex; labial suture clear; mentum widely and deeply concave at base, bisetose, mental tooth simple, blunt at apex; submentum 10-setose; ligula 10-setose, setae being short; palps elongated, slender and subcylindrical, 3 rd maxillary palpomere longer than 4 th , both glabrous; 2 nd labial palpomere longer than 3 rd , bisetose at inner margin, and with two additional setae in subapical and apical parts, respectively; antennae long and pubescent, 1 st antennomere stouter, about 2/3 rds as long as 2 nd , which is about 3/4 ths as long as 3 rd , 4 th slightly longer than 3 rd , 5 th longest, slightly longer than 4 th , 6 th -11 th as long as 4 th ; head (including mandibles) plus pronotum slightly longer than elytra.
Prothorax barrel-shaped, longer than wide, PrL/PrW = 1.53, widest at about third from base; longer or shorter than head excluding or including mandibles, PrL/ HL = 0.76 or 1.09; much wider than head, PrW/HW = 1.45; propleura distinctly tumid, wholly visible from above; wider than pronotum, PrW/PnW = 1.17; pronotum much longer than wide, PnL/PnW = 1.79, wider than head, PnW/HW = 1.24; subparallel-sided, but narrowly and broadly contracted at both ends, making front and hind angles round off, albeit front ones fairly angulate; lateral margins not beaded; PrW/PnW = 1.17; base nearly as wide as front, frontal margin not beaded, finely emarginated in the middle, basal margin widely beaded and nearly straight; both fore and hind lateromarginal setae placed a little mesal to dorsolateral suture, at about basal fourth and apical fifth of pronotum, respectively; disc slightly convex; median line clear, reaching both ends; both transverse impressions not well-marked. Scutellum small and short.
Elytra ovate-oblong, strongly convex; twice as wide as prothorax, much longer than wide, EL/EW=1.89; widest a little behind middle, lateral margins smooth throughout, neither ciliated nor dentate; without prehumeral angles; apex broadly rounded; striae completely disappeared; two dorsal pores present on the location of 3 rd stria, at about basal 2/7 ths and 3/5 ths of elytra, respectively; pre-apical pores located at about apical 2/11 ths of elytra; basal pore present, a little distant from scutellum; humeral group of marginal umbilicate pores not aggregated, composed of five pores, 1 st pore transversally removed mesad and backward, at a little behind level to 2 nd , but a little before the anterior dorsal pore; 3 rd pore close to 2 nd ; 3 rd , 4 th and 5 th pores widely and equidistantly located; 6 th and 7 th pores of middle group shifted behind, lying at about apical fourth of elytra; apical group composed of three pores, apical pore located closer to suture than to elytral margin; only 2 nd and 9 th pores close to marginal gutter, others widely distant from the gutter.
Legs moderately long, femora gradually dilated from base towards subapical portions, then suddenly narrowed towards apices, covered with sparse, long and erect setae; tibiae and tarsi covered with dense and short hairs; tibiae thin, without longitudinal grooves; protarsi short, 1 st tarsomere wider than others, longer than 2 nd and 3 rd combined, but shorter than 2 nd -4 th combined; meso-and metatarsi longer, 1 st tarsomere as long as 2 nd -4 th combined.
Male: Unknown. Etymology. tujia + philus, to refer to the fact that the new species is occurring in the country of Tujia people.
This cave (Fig. 13A, B) lies very close to Feihu Dong, the longest cave in Huoyan Karst, along the main road, and opposite Tujiamei Restaurant. This is a water source cave, with a small underground stream running throughout, the length still being unknown. It is highly moist and muddy. We surveyed as long as about 400 m in the cave, and collected the unique specimen in the dark zone when it was wandering on the wall. The other three trechine species found in the cave are Cathaiaphaenops delprati Deuve, 1996 (Fig. 13C), Sinotroglodytes bedosae Deuve, 1996, andToshiaphaenops ovicollis Uéno, 1999. We visited this and adjacent caves in July, 2015 in order to find more specimens of this interesting beetle, but failed to catch anything.
Generic characteristics. Medium-sized, aphaenopsian type trechine, eyeless, unpigmented and apterous; body very strongly elongate, highly modified morphologically, albeit antennae rather short; head typically aphaenopsoid, extremely elongated as in Dongodytes Deuve, 1993 or some members of Sinaphaenops Uéno & Wang, 1991, much longer than wide, with short and incomplete frontal furrows ending at about middle of head from clypeus, two pairs of supra-orbital pores present, both anterior and posterior pores widely spaced; mandibles moderately long, well-developed, right mandible tridentate; labial suture clear; mentum bisetose, distinctly concave, tooth moderately long, thick and blunt at apex; submentum provided with a row of seven (or eight in a male individual) setae, median one much shorter than others; antennae quite short, extending to about middle of elytra; prothorax distinctly shorter than head, longer than wide, propleura strongly tumid, visible from above; pronotum subquadrate, base nearly as wide as front, both anterior and posterior lateromarginal setae present; elytra strongly elongate, slightly longer than head (including mandibles) plus prothorax; widest behind middle, marginal sides smooth throughout, but ciliate in humeral angle area; humera distinctly angulate; disc moderately convex, rather flat near base, striae well-defined or obliterated, two dorsal and the pre-apical pore present; humeral pores of marginal umbilicate series not aggregated, middle group not close to each other; legs fairly long, 1 st protarsomere in male modified, with a tiny apical denticle inward; tibiae without longitudinal furrow externally; ventrite VII with two pairs of setae in both sexes; aedeagus minute, well-sclerotized, short and broad, strongly arcuate, apex blunt, basal part large, with a small sagittal aileron, inner sac with a fairly large copulatory piece, parameres long, right one longer than left one, broad at apex, each bearing three long apical setae.
Remarks. The true affinities of Wanhuaphaenops gen. n. likewise remain uncertain. Probably the closest match is Shenaphaenops Uéno, 1999 (from northwestern Guizhou Province) because both share several important characters: a wholly pubescent body, humera strongly angulate, right mandibles tridentate, only 1 st protarsomere modified in male, two pairs of supra-orbital pores present on head, two dorsal and the pre-apical pores present on elytron, and ventrite VII 4-setose. However, Wanhuaphaenops gen. n. is easily distinguished from Shenaphaenops by the following characters: (1) head much more elongated, with anterior supra-orbital pore widely distant from posterior one, and labial suture clear (reverse in Shenaphaenops); (2) antennae much shorter than in Shenaphaenops, in which these extending to nearly elytral apex; (3) pronotal posterior lateromarginal setae present in Wanhuaphaenops gen. n., but absent in Shenaphaenops; (4) aedeagus stouter and strongly arcuate in Wanhuaphaenops gen. n., with each paramere bearing three apical setae (Fig. 10C, D), versus aedeagus being slender and slightly arcuate, with each paramere bearing two apical setae in Shenaphaenops (Fig. 4C, D).
Wanhuaphaenops gen. n. might also be found related to the genus Sinaphaenops Uéno & Wang, 1991, one of the most highly modified genera among the Chinese cave-dwelling trechines which ranges from west, southern Guizhou and northernmost Guangxi. Both share a somewhat similar body configuration, but Wanhuaphaenops gen. n. is much smaller and less troglomorphic than Sinaphaenops, the appendages being much shorter, and only one joint of protarsi (1 st protarsomere) is modified in the male, versus two, and a different elytral chaetotaxy.
Etymology. As Cave Songjia Dong represents one branch of the Wanhuayan cave system, the name of this new genus refers to the occurrence of this aphaenopsian beetle in Wanhuayan caves. Gender masculine.

Diagnosis.
A slender and brown cave beetle, with a collar-like neck constriction on head, fairly long fore body which is slightly shorter than elytra, long head which is distinctly longer than prothorax, and distinct humeral angles of elytra.
Body wholly brown, upper surface covered with sparse and minute pubescence, genae and underside of head with some longer setae, abdominal ventrites covered with denser minute pubescence, prosternum, propleura and meso-and metasterna glabrous; legs densely pubescent; microsculpture composed of finely, densely and strongly transverse meshes on upper and underside surfaces. Body elongated, fore body, including mandibles slightly shorter than elytra.
Head strongly elongated, HLm/HW = 2.37-2.5 (mean 2.44), HLl/HW = 1.89-1.94 (mean 1.91), widest at about third of head from labrum, then gently narrowed towards a collar-like constriction of the neck; anterior supra-orbital pore level to the widest point, posterior one at about 1/5 th of head from base, strongly behind end of frontal furrows; distance between anterior and posterior pores greater than that between both anterior pores; frontal furrows fine but well-defined, short, nearly parallelsided in the middle, divergent posteriad, but then convergent before ending points; anterior supra-orbital pores located at the level of mid frontal furrows, posterior ones near collar-like constriction, distance between both posterior pores about half as that between anterior and posterior pores of either side; frons and vertex moderately convex; clypeus quadrate, 4-setose; labrum transverse, widely but shallowly emarginated at front margin; mandibles gently unciform at apex; palps fairly slender, 3 rd and 4 th maxillary palps glabrous, subequal in length; 2 nd labial palp distinctly longer than 3 rd , with two setae at inner margin, and 2-3 additional ones in subapical part, 3 rd glabrous; suborbital pores on ventral side, near a collar-shaped beaded neck; 1 st antennomere thick, as long as 2 nd ; 3 rd antennomere longest, 2.5 times as long as 1 st ; 4 th -7 th and 11 th slightly longer than 8 th -10 th .
Elytra fairly long and elongate ovate, much longer than wide, EL/EW = 1.78-1.82 (mean 1.80), slightly longer than fore body; widest at about 4/9 th from apex, lateral margins finely beaded from base to finish just before apex, finely ciliate throughout,  but remarkably distinct in angular area, nearly straight before and behind humeral angles; base not bordered; disc convex, but basal or humeral area distinctly depressed and almost flat; 2 nd and 3 rd striae well-marked and complete, others more or less oblit-erated; all dorsal and pre-apical setiferous pores located exactly on interrupted and junction points of 2 nd and 3 rd striae, making 3 rd interval with three regular longitudinal meshes between the pores; basal pores located near base, along both sides of scutellum; anterior and posterior dorsal pores at about basal third and middle of elytra, respectively, pre-apical pore at apical fourth of elytra, much closer to suture than to apex of elytra; humeral set of marginal umbilicate pores not aggregated, 1 st -3 rd pores equidistantly located, quite near the marginal gutter, 4 th distant from 3 rd ; 5 th and 6 th isolated from each other, though 5 th closer 6 th than to 4 th .
Male genitalia (Fig. 10C, D): The median lobe of aedeagus very small, but wellsclerotized, with a small but distinct sagittal aileron and a fairly large copulatory piece; parameres well-developed.
Etymology. This species is named in honour of Prof. Yuanhai Zhang (Institute of Karst Geology, Chinese Academy of Geological Sciences, Guilin), who was leading the cave exploration project at Wanhuayan in late August 2015, one of the results being the discovery of this interesting species.
Distribution. China (Hunan) (Fig. 5f). Known only from the limestone Cave Songjia Dong, in the Wanhuayan cave system. Songjia Dong is the upper part of the Wanhuayan cave system, about 10 km away from the main entrance of the Cave Wanhuayan. It is a water cave, with the entrance being as big as that in Wanhuayan (Fig. 15A). The beetles were collected in a dark area about 80 m deep from the entrance (Fig. 15B). A Colpodes species, a trogloxene, was also found in this cave (Fig. 15C).
suggestions which helped us improve the manuscript. This study was sponsored by the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant no. 20134404110026) and National Natural Science Foundation of China (Grant no. 41271602).