Tribasodites pengzhouensis Yin and He, 2020

Yin, Zi-Wei & He, Li, 2020, New Cavernicolous Pselaphinae from Sichuan, China (Coleoptera: Staphylinidae), The Coleopterists Bulletin 74 (4), pp. 827-836 : 831-836

Tribasodites pengzhouensis Yin and He , new species

zoobank.org/ urn:lsid:zoobank.org:act:D7A7C807-9579-419F-98C8-CF1626F81169 ( Figs. 3–4 )

Type Material (9 exx). Holotype: CHINA : ♂, “ China: Sichuan, Chengdu City, Pengzhou, Bailu Town , Tangba Vill. , Ershi Cave , 31°11 ′ 56.64 ′′ N, 103°55 ′ 15.85 ′′ E, 1325 m, 4.iii.2020, L. He & Y. Li, 成都市彭州市白鹿镇塘坝村二十洞” ( SNUC) . Paratypes: CHINA: 1 ♂, 1 ♀, same collection data as holotype ( SNUC) ; 1 ♂, same collection data as holotype, except “ 2020.v.20, Y.Li leg” ( SNUC) ; 2 ♀♀, same collection data as holotype, except “ 2020.v.16 ,

L. He & Y. Li leg” ( SNUC, CCZ); 3 ♀♀, same collection data as holotype, except “ 2020.v.23 , Y. Li leg” ( CLH, CYL) .

Diagnosis. Male. Habitus moderately elongate, body length approximately 3.0 mm; antenna and legs more elongate or slender than free-living or myrmecophilous congeners from China; dorsal surface of head and pronotum finely punctate; pronotum with discal and antebasal denticles; mesotrochanter and apex of mesotibia spinose, metatrochanter with distinct ventral projection; aedeagus with broad, flattened ventral lobe and short, apically rounded dorsal lobe, parameres free, elongate and weakly sclerotized. Female. Habitus and size similar to male, legs lacking modifications.

Description. Male ( Fig. 3A ). Body reddishbrown, length (combined from head, pronotum, elytra, and abdomen) 2.97–2.98 mm. Head ( Fig. 3B ) slightly elongate, length from anterior margin of clypeus to head base 0.64–0.66 mm, width across eyes 0.54–0.59 mm; with small vertexal foveae located far below level with posterior margin of eyes; vertex with long median carina, vertexal foveae connected by distinct U-shaped sulcus, lateral carinae distinct; frons moderately concave between raised antennal tubercles; anterior margin of clypeus slightly angulate at middle; each eye composed of about 40 facets; postocular margins roundly narrowing posteriorly, with long, dense setae. Antenna elongate, length 1.98 mm, antennomeres each elongate, club formed by three apical antennomeres, lacking modification. Pronotum ( Fig. 3B ) approximately as long as wide, length along midline 0.57–0.63 mm, maximum width 0.55–0.60 mm; disc moderately convex; median longitudinal sulcus distinct, lateral sulci thin; median antebasal fovea indicated as oval impression, followed by short median carina, antebasal and discal denticles distinct, connected by longitudinal carinae, with small denticles on lateral margins. Elytra together wider than long, length along suture 0.82–0.89 mm, maximum width 0.90–1.0 mm; discal striae extending to less than half elytral length. Mesoventrite with thick admedial ridges. Metaventrite narrowly impressed along midline, lacking modifications. Legs elongate; mesotrochanter ( Fig. 3C ) with short ventral spine, mesotibia ( Fig. 3D ) with distinct apical spine; metatrochanter ( Fig. 3E ) with large, curved, and apically truncate ventral projection. Abdomen slightly longer than wide, length along midline 0.85–0.97 mm, maximum width 0.78–0.85 mm; tergite 1 (IV) with oblique marginal carinae; discal carinae less than 1/3 tergal length, distinct and close to each other. Aedeagus ( Figs. 3F, G ) strongly sclerotized and asymmetrical, length 0.46 mm, median lobe flattened and broad, narrowed and emarginate at apex; dorsal lobe about half length of median lobe, broad, with round apex in dorsal view.

Female. Similar to male in general appearance and size. Legs lacking modifications. Eyes approximately same size as those of male, each composed of about 40 facets. Measurements (as for male): Body length 3.11 mm; length of antenna 1.94 mm; length/width of head 0.68/ 0.63 mm; pronotum 0.63/ 0.60 mm; elytra together 0.92/ 1.03 mm; abdomen 0.91/ 0.88 mm.

Comparison. The genus Tribasodites is composed of 21 species confined to the Oriental region, including 16 species from China ( Li et al. 2019; Newton 2020). A majority (13 spp.) of the Chinese species were reported to occur in caves, and, together with Tribasodites thailandicus Yin, Nomura and Li from northern Thailand, form a monophyletic group (see Introduction). The new species is placed as a member of Tribasodites based on the denticulate pronotal lateral margins, the protuberant metatrochanter of the male, the presence of distinct discal carinae on tergite 1 (IV), and the aedeagus with a separate dorsal lobe. However, it clearly does not belong to the T. bedosae group based on the simple antennal club and metaventrite of the male, and the broadened median lobe of the aedeagus, which grants ready species identification. A probably related but poorly defined genus, Tribasodes Jeannel , contains one cavernicolous species from the Ryukyu Islands, southwest Japan ( Nomura 2012), which shows some degree of external similarity to the new species described here. These two genera may be only separated by the lack of discal carinae on tergite 1 (IV) in Tribasodes , as mentioned by Jeannel (1960), and shown in Nomura (2012: figs. 4G, H).

Notes on Collection and Biology. The entrance of Ershi Cave is located at the foot of a small hill ( Fig. 4A ). The opening of the entrance ( Fig. 4B ) is so narrow that it allows only one person to crawl in at a time. The cave’ s inside environment is rather moist. One individual ( Fig. 4D ) was found under a stone in the twilight zone about 5 m from the entrance; the other two ( Fig. 4E ) were collected under another stone in the dark zone after going down into a narrow, three-meter-high sinkhole and onto the cave’ s lower floor ( Fig. 4C ).

Distribution. Southwestern China: Sichuan.

Etymology. The new specific epithet is an adjective taken from Pengzhou, where the type locality is located.

Zopherobatrus liyuani Yin and He , new species zoobank.org/ urn:lsid:zoobank.org:act:2B54822A-B0DB-4DEC-A5E6-092A5485AC04 ( Figs. 5–6 )

Type Material ( 1 ex.). Holotype: CHINA: ♂, “ China: Sichuan, Meishan City, Renshou Co , Wangyang Town , Jinquan Vill., Shenxian Cave , 29°44 ′ 56.87 ′′ N, 104°18 ′ 9.65 ′′ E, 488 m, 8.iii.2020, L. He & Y. Li, 眉山市仁寿县汪洋镇金泉村神仙 洞” ( SNUC).

Diagnosis. Male. Body length 3.36 mm; vertex with faint U-shaped sulcus connecting foveae, mediobasal ridge thin and interrupted; maxillary palpus markedly narrow and elongate; eyes strongly reduced, each with 3–4 ommatidia; median longitudinal sulcus of pronotum weakly developed, with thin lateral longitudinal sulci; elytra moderately constricted at base, with thin discal striae; mesotibia with long apical spine in male; tergite 1 (IV) with sides subparallel, narrowed near base; median lobe of aedeagus forked at apex, dorsal lobe broad in lateral view. Female. Unknown.

Description. Male ( Fig. 5A ). Body length (combined from head, pronotum, elytra, and abdomen) 3.36 mm. Body reddish-brown, antennae, mouthparts and tarsi lighter in color; most of dorsal surface covered with moderately long pubescence. Head ( Fig. 5B ) elongate, anterior half rectangular, posterior half subtriangular, length from anterior margin of clypeus to head base 0.74 mm, maximum width across eyes 0.49 mm; surface finely punctate, areas near antennal tubercles roughened; vertex barely convex, foveae posterior to a point level with posterior margins of eyes, with thin U-shaped sulcus connecting vertexal foveae, faint median carina extending from head base to posterior margin of eyes, interrupted at middle; eyes strongly reduced, each indicated by three to four small ommatidia; ocular-mandibular carinae distinct; postocular margin rather long, sharply narrowing from eye toward base; length of antenna 2.49 mm, antennomeres each elongate; maxillary palpus ( Fig. 5C ) with minute palpomere 1 and elongate palpomeres 2–4; palpomere 4 with few semi-transparent thickened setae at anterolateral margins, and each with small apical palpal cone, pedunculate portions approximately half of palpomere length. Pronotum ( Fig. 5B ) longer than wide, with round lateral margins, length along midline 0.75 mm, maximum width 0.62 mm, disc finely punctate, median longitudinal sulcus extending from near base to half pronotal length, lateral longitudinal sulci extending from lateral antebasal foveae to anterior margin, with shallow transverse antebasal sulcus; with thick basolateral ridges. Elytra together approximately as long as wide, length along suture 1.05 mm, maximum width 0.99 mm; disc strongly convex, in lateral view much higher than dorsal level of head and pronotum; each elytron with two small basal foveae; disc finely punctate, covered with moderately long setae. All legs elongate, mesotibia ( Fig. 5D ) with long, straight apical spine. Abdomen slightly wider than long, length along midline 0.82 mm, maximum width 0.86 mm. Tergite 1 (IV) longest, much longer than 2–4 (V–VII) combined, lacking modification, broad and deep basal sulcus separated by pair of broad, long triangular discal carinae, thick marginal carinae indicated only in basal half of tergite; tergites 2–3 (V–VI) subequal in length; tergite 4 (VII) longer than 2 and 3 combined; tergite 5 (VIII) semicircular. Sternite 7 (IX) ( Fig. 5E ) semi-membranous, apical portion rounded and more strongly sclerotized. Aedeagus ( Figs. 5F–H ) asymmetrical, length 0.44 mm; basal capsule with triangular foramen; with long basoventral projection; median lobe broadened at apical part in axial view, split to two major parts at apex ( Fig. 5F ); dorsal lobe broader than median lobe in dorsoventral view; parameres fused to form flattened, lamellate ventral membrane.

Female. Unknown.

Comparison. Zopherobatrus liyuani is the third species of this obligate troglobitic genus that is endemic to the southern Chinese karst areas ( Yin 2020; Yin and Li 2015). The males can be separated from those of the two known congeners by using the following key:

1. Eye totally reduced, without ommatidia (Yin and Li 2015: fig. 2C); maxillary palpomere 4 fusiform, lacking basal pedunculate part (Yin and Li 2015: fig. 2D); tergite 1 (IV) with angulate protuberance at middle near apex (Yin and Li 2015: figs. 1B, 2F); mesotibia with short apical spur (Yin and Li 2015: fig. 2E); Guizhou ....................... ........... Z. tianmingyii Yin and Li, 2015

1 ʹ. Eye strongly reduced, each represented by three to four ommatidia; maxillary palpomere 4 with long pedunculate part at base; tergite 1 (IV) lacking modification; mesotibia with much longer apical spur ........................ 2

2. Maxillary palpus relatively much shorter, palpomere 4 about 5.8 times as long as wide ( Yin 2020: fig. 3A); pronotum lacking median longitudinal sulcus ( Yin 2020: fig. 3C); apical spur of mesotibia slightly curved ( Yin 2020: fig. 3D); aedeagus with median lobe about 1.5 times as broad as basal part of ventral lobe in ventral view ( Yin 2020: figs. 3F–G); Chongqing ................. ................................... Z. lusciosus Yin, 2020

2 ʹ. Maxillary palpus relatively much longer, palpomere 4 about 7.4 times as long as wide ( Fig. 5C ); pronotum with thin median longitudinal sulcus ( Fig. 5B ); apical spur of mesotibia almost straight ( Fig. 5D ); aedeagus with median lobe more than twice as broad as basal part of ventral lobe in ventral view ( Figs. 5F–H ); Sichuan ...................................... .......... Z. liyuani Yin and He , new species

Notes on Collection and Biology. The single adult was collected from Shenxian Cave ( Figs. 6A–D ), where a male of Batrisocenus cavernicolus was also found (see Notes under that species). However, instead of in the twilight zone the new species was encountered in a much deeper area of the cave with complete darkness. The beetle ( Fig. 6E ) was found under a stone ( Fig. 6C ) about 50 m from the entrance.

Distribution. Southwestern China: Sichuan.

Etymology. The new species is dedicated to Yuan Li, co-collector of the type material and many other cavernicolous pselaphine beetles.

Figures

Fig. 3. Habitus and diagnostic characters of Tribasodites pengzhouensis, new species, male. A) Habitus, B) Head and pronotum, C) Mesotrochanter, D) Apical portion of mesotibia, E) Metatrochanter and metafemur. Aedeagus: F) Dorsal view, G) Lateral view. Scale bars: 1.0 mm in A; 0.3 mm in B, E; 0.1 mm in C, D; 0.2 mm in F, G.

Fig. 4. Collection environment and adults in situ of Tribasodites pengzhouensis, new species. Arrow indicates location of the cave entrance. Ershi Cave: A) Nearby environment, B) Entrance, C) Inside environment. D) Adult found under a stone in the twilight zone of the cave, E) Two adults spotted under another stone in the dark zone of the same cave.

Fig. 5. Habitus and diagnostic characters of Zopherobatrus liyuani, new species, male. A) Habitus, B) Head and pronotum, C) Maxillary palpus, D) Apical portion of mesotibia, E) Sternite 7 (IX). Aedeagus: F) Axial view showing apical split of ventral lobe, G) Lateral view, H) Ventral view. Scale bars: 1.0 mm in A; 0.5 mm in B; 0.2 mm in C, D; 0.1 mm in E–H.

Fig. 6. Collection environment and an adult in situ of Zopherobatrus liyuani, new species. Shenxian Cave: A) Nearby environment, arrow indicates location of the cave entrance, B) Entrance, C, D) Inside environment, arrow in C indicates the place where the single male was found. E) Living adult found under a stone in the dark zone of the cave.