Arthromelodes aniqiao, Yin, 2022

Yin, Zi-Wei, 2022, The Batrisini of Tibet: unveiling an enigmatic ant-loving beetle diversity at Earth’s “ Third Pole ” (Coleoptera, Staphylinidae, Pselaphinae), Zootaxa 5111 (1), pp. 1-211 : 15-17

Arthromelodes aniqiao sp. nov.

( Figs 4 , 77A , 98E, F )

Chinese common name: Nj尼桥njà甲

Type material ( 1 ex.). HOLOTYPE: CHINA: ♂, ‘ China: Xizang A. R., Nyingchi City , Mêdog County, A’niqiao, alt 1100 m, 16–18.viii.2005, L. Tang leg. [ƱẪffżẸṘNj尼桥]’ ( SNUC).

Diagnosis. Male. Body length approximately 2.5 mm. Head sub-rounded at base; vertex with transverse sulcus between antennal tubercles and long mediobasal carina, vertexal foveae large and asetose; antenna long, antennomeres each elongate, lacking modifications. Discal stria of elytron extending to apical 2/5 of elytral length. Fore and hind legs simple, mesotrochanter with small trichome on ventral margin, mesotibia with tiny apical spur. Abdomen with large tergite 1 (IV) longer than tergites 2–4 (V–VII) combined; tergite 1 (IV) with transverse central cavity and impressed lateral areas. Aedeagus strongly asymmetric, ventral stalk protruding apically, apex in dorsal view truncate, dorsal lobe strongly curved at apex, parameres reduced and forming single semi-sclerotized structure.

Description. Male. Body ( Fig. 4A ) length 2.33 mm; color reddish-brown, tarsi and mouthparts lighter. Dorsal surface of body covered with moderately long pubescence.

Head ( Fig. 4B ) sub-rounded at base, slightly broader than long, length 0.52 mm, width across eyes 0.55 m; vertex finely punctate, with large, asetose vertexal foveae (dorsal tentorial pits), with curved transverse sulcus between antennal tubercles, mediobasal carina extending from near head base anteriorly to sulcus, antennal tubercles weakly raised; frons broadly and shallowly impressed medially, confluent with clypeus; clypeus with smooth surface, its anterior margin carinate and moderately raised; ocular-mandibular carina complete. Venter with single small gular fovea (posterior tentorial pit), with distinct median carina extending from fovea anteriorly to mouthparts. Compound eyes prominent, composed of approximately 32 large ommatidia. Antenna with loosely formed club, lacking modifications, length 1.20 m; antennomere 1 thick, subcylindrical, 2–11 each elongate, 11 largest, much shorter than 9 and 10 combined, subconical.

Pronotum ( Fig. 4B ) approximately as long as wide, length 0.54 mm, width 0.52 mm, widest at middle; lateral margins rounded; disc slightly convex, finely punctate, with median longitudinal sulcus as long as semicircular lateral sulci in dorsal view; lacking median antebasal fovea, with complete transverse antebasal sulcus connecting lateral antebasal foveae; outer and inner pair of basolateral foveae distinct. Prosternum with anterior part slightly longer than coxal part, with distinct lateral procoxal foveae; hypomeral ridge present at basal 1/2, with punctiform lateral antebasal hypomeral pit; margin of coxal cavity weakly carinate.

Elytra much wider than long, length 0.71 mm, width 0.80 mm; each elytron with two large, asetose basal foveae, lacking subbasal fovea; humerus barely prominent; discal stria extending from outer basal fovea to apical 2/5 of elytral length; subhumeral fovea absent, marginal stria extending posteriorly from subbase to apex.

Mesoventrite short, demarcated from metaventrite by ridged anterior edges of impressed areas where large, setose lateral mesocoxal foveae situated at mesal margins, with pair of admesal carinae; setose median mesoventral foveae moderately separated, lateral mesoventral foveae large and setose, not forked internally. Metaventrite moderately impressed at middle, with pair of setose lateral metaventral foveae, posterior margin with small and narrow split at middle.

Legs elongate, fore and hind legs simple. Mesotrochanter ( Fig. 4C ) with small trichome on ventral margin, mesotibia with tiny tubercle at apex.

Abdomen narrower than elytra, widest at basolateral margins of tergite 1 (IV), length 0.68 mm, width 0.76 mm. Tergite 1 (IV) ( Fig. 4D ) strongly modified, longer than tergites 2–4 (V–VII) combined; with broad, transverse central cavity, anterior margin of cavity broadly projecting at middle, densely setose lateral to projection, posterior margin with X-shaped protrusion at middle and two lateral projections, areas lateral to cavity broadly impressed, with smooth surface; setose basal sulcus separated by mediobasal and one pair of basolateral foveae, with very short triangular discal carinae; tergites 2–4 (V–VII) each with one pair of basolateral foveae, tergite 4 (VII) as long as 2 and 3 combined along middle, tergite 5 (VIII) semicircular, posterior margin roundly emarginate at middle. Sternite 2 (IV) with mediobasal and basolateral foveae in broad setose basal impression, with pair of short lateral carinae; midlength of sternite 2 (IV) approximately as long as 3–5 (V–VII) combined, 3–5 each with one pair of tiny basolateral foveae, sternite 6 (VIII) transverse, posterior margin sinuate, sternite 7 (IX) ( Fig. 4E ) with moderately sclerotized, rounded apex and few long setae along apical margin.

Aedeagus ( Fig. 4F, G ) 0.31 mm long, strongly asymmetric; median lobe with large basal capsule and foramen, basoventral projection short, ventral stalk protruding and in dorsal view truncate at apex; dorsal lobe elongate and strongly curved, narrowing both basally and apically; parameres reduced to single semi-membranous structure.

Female. Unknown.

Comparative notes. This species is most similar to A. angulatus by sharing a similar structure of the male abdominal modifications and the aedeagus. These two species can be separated primarily by the lack of distinct lateral expansions of the abdomen, and the relatively much shorter ventral stalk of the aedeagus of A. aniqiao . Arthromelodes aniqiao is also similar to A. lage , but differs by the slender male protibiae, and the much shorter and less protruding ventral stalk of the aedeagus.

Distribution. Mêdog County, Tibet, SW China ( Fig. 77A , 98E, F ).

Etymology. The specific name is taken from the type locality of this species, i. e., Aniqiao.

Figures

FIGURE 4. Morphology of Arthromelodes aniqiao sp. nov., male. A. Dorsal habitus. B. Head and pronotum. C. Mesotrochanter and mesofemur. D. Tergite 1 (IV). E. Sternite 7 (IX). F, G. Aedeagus, lateral (F) and ventral (G). Scale bars: 0.5 mm in A; 0.3 mm in B; 0.2 mm in D, F, G; 0.1 mm in E.

FIGURE 77. Distribution of Tibetan Batrisini. A. Arthromelodes alpitorus sp. nov. (circle), A. angulatus sp. nov. (triangle) and A. aniqiao sp. nov. (square). B. A. bicolor sp. nov. (circle), A. championi (Jeannel) comb. nov. (triangle) and A. complexus sp. nov. (square). C. A. cona sp. nov. (circle), A. crassicornis sp. nov. (triangle) and A. criniger sp. nov. (square).

FIGURE 98. Environment of and collecting sites at Nyingchi area. A, B. Lage (Ń格). C, D. Hanmi (汗ṁ). E, F. Aniqiao (Nj 尼桥). Photo Credit: A, B by Chao Wu; C, D by Wen-Xuan Bi; E, F by Hao Huang.