Batrisiella guttata, 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 : 85-87

Batrisiella guttata sp. nov.

( Figs 36 , 80C , 100C )

Chinese common name: ųê小毛唇à甲

Type material (8 exx.). HOLOTYPE: CHINA: ♂ , ‘ China: Xizang, Zayü County, valley nr. Zhala Vill., 28°37’23.74”N, 97°21’8.10”E, 2190 m, 2019.vii.28, leaf litter / decomposing log, Z.-W. Yin leg., [ƱẪ察ø县扎 Ń村ṉữ]’ ( SNUC) . PARATYPES: CHINA: 5 ♂♂, 2 ♀♀, same data as that of holotype’ ( SNUC) .

Diagnosis. Male. Body length 1.85–1.91 mm. Head sub-rectangular at base; vertexal foveae moderately large and asetose, lacking sulcus connecting them; antenna moderately elongate; antennomeres slightly elongate or moniliform, antennomeres 9–11 enlarged to form club. Discal stria of elytron extending to apical 3/5 of elytral length. Legs with pro- and mesotrochanter with small ventral tubercle, mesotibia with distinct apical spine. Tergite 4 (VII) with two large and round, disc-like lateral protuberances, tergite 5 (VIII) with broad and deep central cavity, posteromedian portion angularly projecting. Sternite 2 (IV) with pair of admesal setose projections, sternite 3 (V) with two similar, but much smaller projections, sternite 4 (IV) lacking projections but with long, thick setae at middle. Aedeagus strongly asymmetric; median lobe with large basal capsule and basoventral projection, ventral stalk dilated; dorsal lobe curved and transverse, apex pointed; parameres reduced to moderately sclerotized structure. Female. Body length 2.0 mm; antenna shorter, legs lacking tubercle or spine, abdomen lacking modifications, genitalia as in Fig. 7K .

Description. Male. Body ( Fig. 36A ) length 1.85–1.91 mm; color reddish-brown, tarsi and mouthparts lighter. Dorsal surface of body covered with short pubescence.

Head ( Fig. 36B ) sub-rectangular at base, approximately as long as wide, length 0.41–0.42 mm, width across eyes 0.42–0.44 mm; vertex finely punctate, with moderately large, asetose vertexal foveae (dorsal tentorial pits), lacking U-shaped sulcus connecting foveae or mediobasal carina, with transverse sulcus between antennal tubercles; antennal tubercles moderately raised; frons slightly impressed medially, confluent with clypeus; clypeus with smooth surface, its anterior margin carinate and moderately raised; ocular-mandibular carina present. Venter with two small gular foveae (posterior tentorial pits) originating from shared transverse slit, with distinct median carina extending from foveae anteriorly to mouthparts. Compound eyes prominent, composed of approximately 35 ommatidia. Antenna moderately elongate, length 0.90–0.91 mm, apical three antennomeres forming distinct club; antennomere 1 thick, subcylindrical, apicolateral portion with small inner glandular structure, lacking trichome, indistinct, 2–7 each slightly elongate, 8 smallest, moniliform, 9 much larger than 8, 10 slightly longer and broader than 9, 11 largest, slightly shorter than 9 and 10 combined, slightly oval.

Pronotum ( Fig. 36B ) approximately as long as broad, length 0.45 mm, width 0.44–0.45 mm, widest at middle; lateral margins rounded; disc slightly convex, finely punctate, pubescent, median longitudinal sulcus slightly shorter than semicircular lateral sulci in dorsal view, the latter extending from dorsal surface laterally and posteriorly and then fusing with lateral ends of antebasal sulcus; lacking median antebasal fovea, lateral antebasal foveae connected by transverse antebasal sulcus; outer and inner pair of basolateral foveae distinct. Prosternum with anterior part as long as coxal part, with distinct lateral procoxal foveae; hypomeral ridge extending from base to middle of anterior part, with punctiform lateral antebasal hypomeral pit; margin of coxal cavity weakly carinate.

Elytra much wider than long, length 0.63 mm, width 0.74 mm; each elytron with two large, asetose basal foveae, lacking subbasal fovea; discal stria extending from outer basal fovea to apical 3/5 of elytral length; humerus weakly prominent, with small subhumeral fovea, sulcate marginal stria extending from fovea to posterior margin of elytron.

Mesoventrite short, demarcated from metaventrite by ridged anterior edges of impressed areas where lateral mesocoxal foveae situated at mesal margins, with pair of thin admesal carinae; setose median mesoventral foveae widely separated, lateral mesoventral foveae large and setose, broadly forked internally; intercoxal process short. Metaventrite broadly impressed at middle, with large, setose lateral mesocoxal foveae and pair of smaller, setose lateral metaventral foveae, posterior margin with small and narrow split at middle.

Legs moderately elongate; pro- and mesotrochanter each with ventral tubercle, mesotibia with distinct apical spur.

Abdomen widest at lateral margins of tergite 1 (IV), length 0.50–0.55 mm, width 0.67 mm. Tergite 1 (IV) longer than tergites 2–4 (V–VII) combined in dorsal view, setose basal sulcus separated by mediobasal and one pair of basolateral foveae, with pair of triangular discal carinae; tergites 2–4 (V–VII) tightly compressed, each with one pair of basolateral foveae, tergite 4 (VII) ( Fig. 36C ) slightly shorter than 2 and 3 combined along middle, each side with one large and round projection, tergite 5 (VIII) ( Fig. 36C, D ) broad and slightly transverse, with large central cavity, posteromedian part angularly projecting and with dense setae at apex of projection, with pair of much smaller tubercles lateral to protuberance, each with few thickened setae, anterior margin of cavity with pair of small median protuberances, anterior margin of tergite with pair of round admesal tubercles. Sternite 2 (IV) with large mediobasal and pair of broad, setose basolateral sockets, midlength approximately as long as 3–5 (V–VII) combined, with pair of large, setose admesal projections ( Fig. 36E, F ), 3–5 each with one pair of indistinct basolateral foveae, sternite 3 (V) with pair of small, setose admesal projections ( Fig. 36E, F ), sternite 4 and 5 (VI and VII) lacking projections, but with thickened setae at middle, sternite 6 (VIII) as long as 5 (VII) at middle, posterior margin slightly emarginate, sternite 7 (IX) ( Fig. 36G ) transverse, rounded triangular, weakly sclerotized.

Aedeagus ( Fig. 36H–J ) 0.33 mm long, strongly asymmetric; median lobe with large basal capsule and foramen, ventral stalk strongly dilated; dorsal lobe transverse, strongly curved, narrowing from middle apically, with pointed apex; parameres reduced to single moderately sclerotized structure.

Female. Similar to male in external morphology; antenna shorter; each compound eye composed of approximately 22 ommatidia; humeral angle rounded; legs lacking tubercles or spines; abdomen lacking modifications. Measurements (as for male): body length 2.0 mm; length/width of head 0.40/ 0.41–0.43 mm, pronotum 0.42– 0.45/ 0.43–0.44 mm, elytra 0.53–0.59/ 0.70–0.74 mm; abdomen 0.68/ 0.66–0.69 mm; length of antenna 0.82–0.87 mm; maximum width of genitalia ( Fig. 36K ) 0.24 mm.

Comparative notes. Batrisiella guttata can be readily separated from all congeners by the unique structure of the modifications on tergites 4 and 5 (VII and VIII), sternites 2 and 3 (IV and V), as well as the form of the aedeagus.

Distribution. Zayü County, Tibet, SW China ( Figs 80C , 100C ).

Etymology. The specific epithet ‘ guttâtus, - a, - um ’ is a Latin adjective meaning ‘spotted, speckled’, referring to the round lateral projections of male tergite 4 (VII) of the new species.

Figures

FIGURE 7. Morphology of Arthromelodes complexus sp. nov. (A–I. Male. J. Female). A. Dorsal habitus. B. Head and pronotum. C. Protibia. D. Mesotrochanter. E. Mesotibia. F. Tergite 1 (IV). G. Sternite 7 (IX). H, I. Aedeagus, lateral (H) and ventral (I). J. Genitalia. Scale bars: 0.5 mm in A; 0.3 mm in B; 0.2 mm in C–F; 0.1 mm in G–J.

FIGURE 36. Morphology of Batrisiella guttata sp. nov. (A–J. Male. K. Female). A. Dorsal habitus. B. Head and pronotum. C, D. Tergite 5 (VIII). E, F. Sternites 2–4 (IV–VI). G. Sternite 7 (IX). H–J. Aedeagus, dorsal (H), lateral (I) and ventral (J). K. Genitalia. Scale bars: 0.5 mm in A; 0.2 mm in C–F; 0.05 mm in F; 0.1 mm in G–K.

FIGURE 80. Distribution of Tibetan Batrisini. A. Batriscenaulax campestris sp. nov. B. Batrisiella acclivis sp. nov. (circle), B. beibeng sp. nov. (triangle), B. bomea sp. nov. (square) and B. concisa sp. nov. (cross). C. B. curvitibialis sp. nov. (circle), B. ganma sp. nov. (triangle), B. guttata sp. nov. (square) and B. zhujianqingi (diamond).

FIGURE 100. Environment of and collecting sites at Nyingchi area (A–E) and Chamdo (ăƀ) (F). A. 80K. B. 96K. C–E. Xiachayu (T察ø). F. pass of Jueba Mountain (ẅ巴山口), Markam (Ẽ康). Photo Credit: A by Zhong Peng; B by Xiao-Bin Song; F by Wen-Xuan Bi.