Mircogioton coomani Orchymont, 1937

Jia, Fenglong, Lin, Renchao, Li, Bijun & Fikacek, Martin, 2015, A review of the omicrine genera Omicrogiton, Mircogioton and Peratogonus of China (Coleoptera, Hydrophilidae, Sphaeridiinae), ZooKeys 511, pp. 99-116 : 106-107

Taxon classification Animalia Coleoptera Hydrophilidae

Mircogioton coomani Orchymont, 1937 Figs 5-6, 14, 20

Mircogioton coomani Orchymont, 1937: 464.

Ischyromicrus cognitus Malcolm, 1981: 267. New synonym.

Mircogioton cognitus (Malcolm); Hansen 1991: 226

Material examined.

CHINA, Yunnan: 2 males, 6 unsexed spec. (SYSU, NMPC): Laiyanghe, Xinzhai Cun, 1487 m, 22.631°N, 101.132°E, 21.v.2011, Song Keqing lgt.; 1 male, 2 unsexed spec (SYSU): Mandian Nabanhe Conv., 11.i.2004, Li & Tang lgt.; 1 spec. (NMPC): Laiyanghe, Yutang village, in decaying banana trunk, 22.v.2011, Keqing Song lgt. VIETNAM: 1 male (IZCAS): Tonkin, Hoa-Binh, leg. A. de Cooman.

Diagnosis.

Body length 3.2-3.4 mm, width 2.2 mm. Dorsal surface dark brown, ventral surface brown to dark brown. Labrum weakly bisinuate on anterior margin, not distinctlx projecting anteriad. Scapus ca. 2.2 × as long as antennomeres 2-5 combined, slightly shorter than antennal club. Head, pronotum and elytra with similar sparse and fine punctation, interstices without fine microsculpture; elytra with 10 series of punctures, series 6-7 abbreviated anteriorly. Prosternum strongly tectiform, sharp anteriorly. Mesoventral elevation much longer than wide, with distinct longitudinal groove medially, posteriorly fused with metaventral process, not projecting posteriad into a process overlapping metaventrite. Metaventrite with a longitudinal glabrous elevated band medially, forming together with mesoventral plate a joint meso-metaventral elevation. Phallobase ca. 0.3 × as long as paramere; paramere rather wide throughout, outer margin slightly concave subapically, apex semicircular. Median lobe slightly narrower than paramere, lateral margin almost parallel, apex narrowly rounded, gonopore of moderate size, subapical (Fig. 20).

Differential diagnosis.

Mircogioton coomani differs from Mircogioton spinosus Bameul, 1993, Mircogioton seriatus Hebauer, 2006 and Mircogioton irregularis Hebauer, 2006 in mesoventrite fused with metaventral process (in contrast, mesoventrite is projecting into a long process overlapping metaventrite in the latter three species). It differs from Mircogioton grandis Bameul, 1993 and Mircogioton julieae (Malcolm, 1981) by the anterior margin of the labrum bisinuate (in contrast, labrum is simply concave on anterior margin in the latter two species). From Mircogioton julieae it also differs by apically broad paramere and apex of median lobe not distinctly narrowed. From Mircogioton grandis it may be also distinguished by smaller body size (up to 3.5 mm, in comparison with 3.8 mm in Mircogioton grandis ).

Remark.

This species was described by d’Orchymont (1937) based on a single female collected by A. de Cooman in "Tonkin, Hoa Binh". The senior author examined one male collected by the same collector and bearing the same label data. Except of clearly being a part of the same material from which Mircogioton coomani was collected, the examined specimen agrees in all details with the original description. We therefore consider it represents Mircogioton coomani although we have not checked the female holotype.

Malcolm (1981) described Ischyromicrus cognitus Malcolm, 1981 based on a female from upper Mekong (later transferred to Mircogioton by Hansen (1991)). The species was redescribed by Bameul (1993). The characters described by Malcolm (1981) and Bameul (1993) are identical with the specimens of Mircogioton coomani in our hands. The type locality of Mircogioton cognitus is situated in northeastern Laos not far from the border with China rather than in Vietnam as supposed by Malcolm (1981) ( Bameul 1993, Hansen 1999). Bameul (1981) moreover noticed that "in the description of Mircogioton cognitus , no characters really differ from those given by d’Orchymont (1937) in his description of Mircogioton coomani " and supposed that Mircogioton cognitus is synonym of Mircogioton coomani . We are following this opinion here and consider Mircogioton cognitus as a junior subjective synonym of Mircogioton coomani .

Biology.

The recently collected specimens examined here were found in decaying banana trunk (K.-Q. Song and L. Tang, pers. comm.).

Distribution.

China (Yunnan), northern Laos. New genus and species for China.