Peratogonus reversus Sharp, 1884

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 : 107-109

Taxon classification Animalia Coleoptera Hydrophilidae

Peratogonus reversus Sharp, 1884 Figs 8-12, 21-22

Peratogonus reversus Sharp, 1884: 461.

Type material examined.

Syntypes: 2 specimens on one card (BMNH): " Peratogonus reversus Type DS Nagasaki 14.4.81 // Japan G. Lewis Sharp coll. 1905 - 313"; 1 upside down spec. (BMNH): " Peratogonus reversus Sharp // Japan G. Lewis // 30.3.81".

Additional material examined.

JAPAN: 1 male (BMNH): "Japan, Kobe. Mayasan 14.vi.29 JEA Lewis. Nr 1530"; 1 male (NMPC): Kanagawa Pref., Manazuru Peninsula, 4.xi.2006, P. Jaloszynski lgt.; 1 spec. (NMPC): Chiba Pref., Kôzaki shrine, Kôzaki-machi, 15.x.2001, P. Jaloszynski lgt. CHINA: Guangdong: 1 male (SYSU): Conghua, Liuxihe forest park, 16.v.2012, Tong Xiaoli leg. (in Chinese); 1 male (SYSU): Fengkai, Heishiding Natural Reserve, 23°27.9'N 111°54.3'E, 190-260 m, Fenglong Jia leg.; 1 male (NMPC): W of Qixing, Heishiding nature reserve, sifting of moist leaf litter in the dried-up streambeds and along the streams in the primary lowland forest, 190-260 m a.s.l., 23°27.9'N, 111°54.3'E, 1.-3.v.2011, Fikáček & Hájek lgt. Jiangxi: 1 male (NMPC): Jinggangshan Mts., Xiangzhou (forested valley S of the village), cut and decaying tops of bamboo trunks at side of a trail in the secondary forest and among the fields, 26°35.5'N, 114°16.0'E, 374 m, 26.iv.2011, Fikáček & Hájek lgt. Taiwan: 1 male, 9 spec. (NMPC, SYSU): Maoli County, Nanjhuang Twnsh., S-Nanjhuang Rd. 124, km 3 + forest road, forest compost, 26.x.2010, S. Vít lgt.

Diagnosis.

Body length 2.1 mm, width 1.5 mm, strongly convex. Head and pronotum with fine microsculpture between punctures. Elytra with 10 striae, striae 1-5 reaching elytral base, striae 6-10 abbreviated anteriorly, not reaching base; elytral intervals with distinct fine punctures, without microsculpture between punctures. Prosternum steeply raised in middle to form a triangular medially carinate tablet. Mesoventrite flat medially, widely fused with metaventrite. Metaventrite laterally with much coarser and stronger punctures than on its median portion. Aedeagus (Figs 21-22) with phallobase ca. as long as paramere, tube-like; paramere broad basally, gradually narrowing towards apex; median lobe slender, parallel-sided, with very long basal struts, gonopore indistrinct, apex slightly emarginate.

Differential diagnosis.

This species can be easily distinguished from Peratogonus grandis Malcolm, 1981 occurring in India (Sikkim) by punctures on the lateral portion of the metaventrite much deeper and larger than medially. From Peratogonus corporaali Orchymont, 1926 occurring in Indonesia (Java), it may be distinguished by pronotum with distinct microsculpture between punctures, elytra with striae 6-10 not reaching elytral base (stria 8 almost reaching base, striae 9-10 reaching base in Peratogonus corporaali ), elytral intervals with distinct punctures, flat mesoventral plate, and metaventrite with coaser and sparser punctures medially.

Remark.

This species was firstly described from Nagasaki, Kyushu in southern Japan by Sharp (1884). It was subsequently reported from Taiwan by Knisch (1921). The comparison of the specimens from Taiwan and southern continental China revealed that they are identical with those from Japan.

When Malcolm (1981) described Peratogonus grandis Malcolm, 1981, he diagnosed it from Peratogonus reversus by the different body size (2.21 × 1.64 mm in Peratogonus grandis versus 1.72 × 1.31 in Peratogonus reversus ) and by the shallower and smaller punctures on lateral portion of the metaventrite. The material examined by us revealed that the specimen of Peratogonus reversus examined by Malcolm (1981) was smaller than its individuals usually are (i.e. body length 1.9-2.2 mm). Therefore, the body size can not be used as a reliable character to distinguish the two species, in contrast to the punctation of the metaventrite, which seems to be a reliable character to distinguish the two species.

Biology.

Most specimens examined here were found by sifting forest leaf litter.

Distribution.

China (Guangdong, Jiangxi, Taiwan), Japan (Honshu, Kyushu). New genus and species for mailand China.