While surveying the Korean aquatic beetle fauna, we collected two unusual small hydrophilid species. After detailed studies of their comparative morphology, we identified them as
The genus
In this paper, we report
Order Coleoptera Linne, 1758
Family Hydrophilidae Latreille, 1802
Subfamily Hydrochinae Thomson, 1859
1*Genus Hydrochus Leach, 1817
2*Hydrochus chubu Balfour-Browne & Sato, 1962 (Figs. 1A, 2)
Material examined. Korea: 1♀, Jeju Prov., Bukjeju-gun, Jocheon-eub, Seonheul-ri, 26 Jul 2005, Lee SH,
slide, CNUIC); 1♀, 22 May 2006, Lee DH (CNUIC); 1♀, 22 Aug 2007, Lee SH (CNUIC).
Description. Body 3.2-3.7 mm, elongated, with many punctures (Fig. 1A). Head black, pronotum and elytra dark brown. Ventral surface grey with hydrofuse pubescence but leg yellowish brown to brown. Head depressed at middle part, epicranial suture indistinct. Antennae with 7 antennomeres and 5-7 clubbed with pubescence, antennomere 1 as long as 2- 4 combined, apical part of 4 dish-shaped. Mentum with large and sparse punctures, anterior margin rounded (Fig. 2A).
Labrum with many long setae on anterior and lateral parts. Mandible with many short setae on apico-lateral part. Maxillary palpomere 1 with one seta on sub-basal part, 2 with two setae on sub-basal part, 4 with one seta on sub-apical part. Labial palpomere 1 longer than 2; 3 with one long seta on apical part. Pronotum more or less reversed pentagonal with large seven impressions; lateral margin crenulated. Elytron with 4 large membranous punctures on apical part, diameter as long as elytral punctures (Fig. 2B). Pro- and mesofemur with hydrofuse pubescence on basal part, metafemur with hydrofuse pubescence on antero-basal third (Fig. 2C). Tarsomere 5 as long as 1-4 combined. Sternite VII with 10 large punctures on middle part (Fig. 2D), semitransparent plate with many spines (Fig. 2D).
Remarks. This species can be distinguished from
Distribution. Korea, Japan.
1*Hydrochus japonicus Sharp, 1873 (Figs. 1B, 3)
Material examined. Korea: 1♂, Jeju Prov., Bukjeju-gun, Jocheon-eub, Seonheul-ri, 11 Jun 2005, Lee DH,
Description. Body 3.4-3.7 mm, elongated, with many punctures (Fig. 1B). Head, pronotum bluish and elytra yellowish grey. Ventral surface dark grey with hydrofuse pubescence. Head depressed at middle part, epicranial suture indistinct. Antennae with 7 antennomeres and 5-7 clubbed with pubescence (Fig. 3A), antennomere 1 as long as 2-4 combined, apical part of 4 dish-shaped. Mentum pointed at the anterior margin and with sparse and large punctures (Fig. 3B). Labrum with many long setae on anterior and lateral parts. Mandible with many short setae on apico-lateral part. Maxillary palpomere 1 with one seta on sub-basal part (Fig. 3C), 2 with two setae on sub-basal part, 4 with one seta on sub-apical part. Labial palpomere 1 longer than 2, 3 with one long seta on apical part. Pronotum more or less reversed pentagonal, large seven impressions present (Fig. 3D), lateral margin of pronotum crenulated. Elytron with 5 large membranous punctures on apical part, diameter as long as elytral punctures (Fig. 3E). Pro- and mesofemur with hydrofuse pubescence on basal part, metafemur with hydrofuse pubescence on antero-basal forth (Fig. 3F). Tarsomere 5 as long as 1-4 combined (Fig. 3G). Sternite VII with 10 large punctures on middle part (Fig. 3H), semitransparent plate with many spines. Median lobe of aedeagus shorter than paramere, apical part V-shaped (Fig. 3I). Apical part of paramere sinuate (Fig. 3I).
Remarks. This species can be distinguished from
Distribution. Korea, China, Japan.
Korean name: 1*곰보물땡땡이속, 2*갈색곰보물땡땡이 (신칭) Korean name: 1* 곰보물땡땡이