Arthromelodes championi ( Jeannel, 1960 ) 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 : 19-21

Arthromelodes championi ( Jeannel, 1960) , comb. nov.

( Figs 6 , 77B , 88A, B , 89 , 90 , 93D–G )

Chinese common name: K氏njà甲

Plocamarthrus championi Jeannel, 1960: 423 ; figs 29, 30. Type locality: United Provinces. Kumaon: Chakrata div., Deoban, Dodoro Khud, Khedar Khud, alt. 2,500 m.

Additional material examined (56 exx.). 5 ♂♂, 26 ♀♀, ‘ China: Xizang, Gyirong County, Gyirong Valley, pass nr. Jifu Vill. , 28°21’35”N, 85°20’46”E, 2600–2700 m, 19.vi.2021, Z. Peng, Z. Yin & W. Zhang leg., ƱẪU喀NJ吉 PW吉ė村ṉữ山ě ; 1 ♂, same data as precedents, except ‘slope nr. Jifu Vill. , 28°22’37”N, 85°19’41”E, 2400- 2700 m, 22.vi.2021, ƱẪU喀NJ吉PW吉ė村ṉữ山坡 ’; 7 ♂♂, 11 ♀♀, same collectors and also from Gyirong Valley, except ‘pass nr. Ru Kupuqiong , 28°25’47”N, 85°15’50”E, 3000 m, 20.vi.2021, ƱẪU喀NJ吉PWả库 âAEṉữ ’; 1 ♂, ‘ China: Xizang, Dinggyê County, Zhêntang Town, Xiuxiongma Vill. , 27°54’11”N, 87°22’42”E, 2700-3000 m, 25.vi.2021, Z. Peng, Z. Yin & W. Zhang leg., ƱẪU喀NJŤĠ县ĿƋWšŏ玛村 ’; 1 ♂, 3 ♀♀, same data as precedent, except ‘ Nadang Vill. , 27°51’26”N, 87°26’59”E, 2500 m, 28.vi.2021, Yin & Zhang, ƱẪŤ Ġ县ĿƋWḄ当村 ’; 1 ♂, same data as precedent, except ‘ Ganma Zangbo Valley , 27°51’50”N, 87°24’24”E, 2400 m, 28.vi.2021, Z. Peng leg., ƱẪŤĠ县ĿƋWH玛Ẫ布河ě ’ (all paratypes in SNUC) .

Diagnosis. Male. Body length over 2.1 mm. Head rounded at base; vertex with deep transverse sulcus between antennal tubercles and long mediobasal carina, vertexal foveae moderately large and asetose; antenna moderately elongate, antennomeres each sub-moniliform to slightly elongate, antennomeres 7 and 8 moderately enlarged, 9 strongly expanded mesally. Discal stria of elytron extending posteriorly to more than apical 1/3 of elytral length. Fore and hind legs simple, mesotrochanter with acute spine on ventral margin, mesotibia with large, subtriangular apical spine. Abdomen with large Tergite 1 (IV) longer than tergites 2–4 (V–VII) combined in dorsal view, simple. Aedeagus strongly asymmetric, ventral stalk in dorsal view broad through length, strongly curved leftwards in ventral view, dorsal lobe thin and elongate, strongly curved downwards at apical part, parameres reduced and forming single membranous structure. Female. Body length slightly over 2.0 mm, antenna and legs lacking modifications, genitalia as in Fig. 6H .

Redescription (based on populations of China). Male. Body ( Fig. 6A ) length 2.17–2.19 mm; color reddishbrown, tarsi and mouthparts lighter. Dorsal surface of body covered with short pubescence.

Head ( Fig. 6B ) rounded at base, approximately as long as wide, length 0.45–0.46 mm, width across eyes 0.52 mm; vertex finely punctate, with moderately large, asetose vertexal foveae (dorsal tentorial pits), with deep, slightly curved transverse sulcus between antennal tubercles, distinct mediobasal carina extending from head base anteriorly to sulcus, antennal tubercles moderately 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 35 moderately large ommatidia. Antenna 1.03 mm long, with moderately enlarged antennomeres 7–8 and modified antennomere 9 ( Fig. 6C ); antennomere 1 thick, subcylindrical, 2–6 each elongate, successively shorter, 7 much larger than 6 and slightly larger than 8, 9 strongly expanded at mesal margin, 10 as long as wide, sub-trapezoidal, 11 largest, simple, as long as 9 and 10 combined, sub-fusiform.

Pronotum ( Fig. 6B ) approximately as long as wide, length 0.51–0.52 mm, width 0.51 mm, widest at middle; lateral margins rounded; disc moderately convex, finely punctate, with median longitudinal sulcus slightly shorter than semicircular lateral sulci in dorsal view; lacking median antebasal fovea, with complete, deep 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 small 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 0.67–0.68 mm, width 0.84–0.85 mm; each elytron with two large, widely separated basal foveae, lacking subbasal fovea; humerus angularly prominent; discal stria extending from outer basal fovea to more than apical 1/3 of elytral length; subhumeral fovea small, marginal stria extending posteriorly from fovea 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 in transverse opening, broadly separated, lateral mesoventral foveae large and setose, not forked internally. Metaventrite broadly and shallowly impressed at middle, with pair of setose lateral metaventral foveae, posterior margin with small and narrow split at middle. Longitudinal marginal ridge of meso- and metaventrite complete.

Legs elongate, fore and hind legs simple. Mesotrochanter with acute ventral spine, mesotibia ( Fig. 6D ) with large, sub-triangular, blade-like spine at apex.

Abdomen slightly narrower than elytra, widest at basolateral margins of tergite 1 (IV), length 0.60–0.61 mm, width 0.76 mm; lacking modifications. Tergite 1 (IV) longer than tergites 2–4 (V–VII) combined; setose basal sulcus separated by mediobasal and one pair of basolateral foveae, lacking discal carinae; tergites 2–4 (V–VII) each with one pair of basolateral foveae, tergite 4 (VII) shorter than 2 and 3 combined along middle, tergite 5 (VIII) semicircular, posterior margin roundly emarginate at middle. Sternite 2 (IV) with large mediobasal and broad basolateral foveae, lacking lateral carinae; midlength of sternite 2 (IV) slightly longer than sternites 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. 6E ) slightly oval, moderately sclerotized, with scattered long setae along apical margin.

Aedeagus ( Fig. 6F, G ) 0.42 mm long, strongly asymmetric; median lobe with large basal capsule and elongate foramen, basoventral projection moderately long, ventral stalk in dorsal view broad though entire length, in ventral view strongly curved towards left; dorsal lobe extremely elongate and strongly curved downwards at apex, gradually narrowing from base towards apex; parameres reduced to single membranous structure.

Female. Similar to male in external morphology; antenna slightly shorter; antenna and legs lacking modifications; each compound eye composed of approximately 21 ommatidia; elytra constricted at bases, humeral angle rounded. Measurements (as for male): body length 2.09–2.12 mm; length/width of head 0.44–0.46/ 0.48–0.49 mm, pronotum 0.49/ 0.49 mm, elytra 0.59–0.60/ 0.79–0.82 mm; abdomen 0.69–0.71/ 0.78–0.79 mm; length of antenna 0.95–0.97 mm; maximum width of genitalia ( Fig. 6H ) 0.35 mm.

Comparative notes. This is the type species of Jeannel’s Plocamarthrus and center of the P. championi group. The males can be readily separated from all congeners of the group by the enlarged antennomeres 7–8 and mesally expanded antennomere 9, in combination with the distinct apical spine of the mesotibia and a dorsally broad, strongly curved median lobe of the aedeagus.

Distribution. Himachal Pradesh and Uttarakhand, India; Gyirong County and Dinggyê County, Tibet, SW China ( Figs 77B , 88A, B , 89 , 90 , 93D–G ). New country record for China.

Figures

FIGURE 6. Morphology of Arthromelodes championi (Jeannel) comb. nov. (A–G. Male. H. Female). A. Dorsal habitus. B. Head and pronotum. C. Antennomeres 7–11. D. Mesotibia. E. Sternite 7 (IX). F, G. Aedeagus, lateral (F) and ventral (G). H. Genitalia. Scale bars: 0.5 mm in A; 0.3 mm in B; 0.2 mm in C, D, F, G; 0.1 mm in E, H.

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 88. Environment of and collecting sites at Gyirong Valley (吉P沟). A. General environment of Ru Kupuqiong. B. Collecting site at Ru Kupuqiong (ả库âAE). C. A stone by the path at Ru Kupuqiong, under which two larvae (D) and an adult (E) of Hingstoniella lata Jeannel were spotted. Photo Credit: A, D, E by Wen-Xuan Zhang.

FIGURE 89. Environment of and collecting sites at Gyirong Valley. A. General environment of the valley. B–E. Forests (B, E) and collecting sites (C, D) in the valley. D. A sign of Kiypu Village (吉ė村), which is the entrance to the forest. Photo Credit: A by Wen-Xuan Zhang.

FIGURE 90. Environment of and collecting sites at Gyirong Valley. A. General environment of the valley. B. A slope dominated by conifers along the valley. C. Zhong Peng searching pselaphines under the bark of a fallen trunk.

FIGURE 93. Environment of and collecting sites at Zhêntang Valley (ĿƋ沟). Slopes at altitudes of 3700 m (A), 4000 m (B), and 3050 m (C). D. Nadang Village (Ḅ当村). E. Road to Xiuxiongma Village (šŏ玛村). F, G. Environment of Ganma Zangbo Valley (HḼẪ布河ě). Photo Credit: F, G by Zhong Peng.