Minutotrechus Deuve, 2016

Deuve, Thierry, Kavanaugh, David H. & Liang, Hongbin, 2016, Inventory of the Carabid Beetle Fauna of the Gaoligong Mountains, Western Yunnan Province, China: Species of the Tribe Trechini (Coleoptera: Caraboidea), with Descriptions of Four New Genera, One New Subgenus and 19 New Species., Proceedings of the California Academy of Sciences 63 (12), pp. 341-455 : 363

Genus Minutotrechus Deuve and Kavanaugh, gen. nov.

TYPE SPECIES.— Stevensius minutus Uéno, 1997 .

DERIVATION OF GENUS GROUP NAME.— The genus group name (masculine) is a combination of the Latin adjective, minutus , meaning very small, and the generic name, Trechus , in reference to the small size of members of this genus.

DIAGNOSIS.— Adults of this genus ( Fig. 11a ) can be recognized by the following combination of character states: size small (BL = 2.7 to 2.9 mm), apterous, body color brown to black; head large with small but protruding eyes, their diameter shorter than length of tempora; mandibles short, obtusely bidentate, mentum and submentum at least partial fused, labial suture partially perceptible, mentum with medial tooth truncate; pronotum small, cordate, narrow (ratio PW/PL = 1.25), very convex, globulose, glabrous, basal angles small and subrectangular, slightly obtuse, with basal margin broadly lobate, basal area convex, both midlateral and basolateral setae present; elytra ovoid and markedly convex, with discal striae 2 to 8 striae effaced, stria 1 deeply impressed and punctate, both anterior and middle discal setae present, preapical seta absent, lateral groove abruptly terminated anteriorly at humerus; legs short, protibiae without longitudinal furrows.

COMMENTS.— This new genus is known from only six female specimens that were originally assigned by Uéno (1997) to genus Stevensius Jeannel (1923) of the eastern Himalayan region. However, they can be distinguished from members of that genus by their smaller head size, protibiae without longitudinal furrows, pronotum more cordate and with basal angles smaller and basal margin broadly lobate and elytra with the lateral groove abruptly terminated anteriorly at humerus. Minutotrechus appears to be more closely related to Hubeitrechus Deuve (2005) , but its members can be distinguished from those of the latter in having the mentum and submentum at least partial fused, the mandibular teeth short and obtuse, the pronotum with the median basal area more convex and basal margin broadly lobate and without margination, and lateral groove abruptly terminated at the humerus. Because no male specimens of Minutotrechus have been collected to date, we do not know if male protarsomeres 1 and 2 are elongate as in males of Hubeitrechus or broad as in Stevensius males. Members of this new genus can also be compared with those of Uenoites Belousov and Kabak (2016) , from which they differ in having the right mandible obtusely bifid (tridentate in Uenoites members), the protibiae without longitudinal furrows (longitudinal furrows present in Uenoites members), the mentum and submentum at least partial fused (not fused in Uenoites members), elytra with only two discal setae (three or more discal setae present in Uenoites members), the preapical seta absent (present in Uenoites members) and the lateral groove abruptly terminated at humerus (gradually narrowed anterior to humerus in Uenoites members).

GEOGRAPHICAL DISTRIBUTION.— This genus currently is known only from the type species, which is known only from the southern part of the Gaoligong Shan region of western Yunnan Province, China .

Figures

FIGURE 11. Minutotrechus minutus (Uéno); a. Dorsal habitus (paratype). scale line = 1.0 mm; b. Map of locality records (red circle) for M. minutus in the Gaoligong Shan region. Scale lines a = 0.5mm, b = 100 km.