Lobrathium (Lobrathium) bilobatum, Assing, 2010

Assing, Volker, 2010, On the Lathrobiina of Taiwan (Coleoptera: Staphylinidae: Paederinae), Beiträge Zur Entomologie = Contributions to Entomology 60 (2), pp. 301-361 : 330-331

Lobrathium (Lobrathium) bilobatum sp. n. ( Figs 97-106 )

Type material:

Holotype ♂: " Taiwan, Chiayi Hsien, Alishan, Sister Ponds, 2180 m, 26.IV.1990, A. Smetana [T24] / Holotypus ♂ Lobrathium bilobatum sp. n., det. V. Assing 2010" (cSme). Paratypes: 16 exs.: same data as holotype (cSme, cAss); 1 ex.: " Taiwan, Chiayi Hsien, Tjuchung, 2200 m, 27.IV.1990, A. Smetana [ T 26]" (cAss); 14 exs. [partly teneral]: " Taiwan, Ilan Hsien, Taipingshan, 1880 m, 14.VII.93, A. Smetana [ T 152]" (cSme, cAss); 27 exs. [partly teneral]: " Taiwan, Ilan Hsien, Taipingshan, 1820 m, 15.VII.93, A. Smetana [ T 153]" (cSme, cAss); 26 exs. [partly teneral]: " Taiwan, Ilan Hsien, Taipingshan, 1820 m, 15.VII.93, A. Smetana [ T 154]" (cSme, cAss); 2 exs.: Taiwan, Nantou Hsien, Meifeng, 2130 m, 12. V.1991, A. Smetana [ T 78]" (cAss); 1 ex.: " Taiwan, Nantou Hsien, Meifeng, 2130 m, 4. V.1998, A. Smetana [ T 199]" (cSme); 3 exs.: " Taiwan, Kaohsuing [sic] Hsien, Kuanshan trail at Kaunshanchi Riv., 2400 m, 20.VII.93, A. Smetana [ T 158]" (cSme, cAss); 1 ex.: " Taiwan, Kaohsiung Hsien, Crk. 2 km E Tien Chi, Hwy. 20, 2400 m, 22.VII.93, A. Smetana [ T 161]" (cSme); 1 ex. [teneral]: " Taiwan, Kaohsiung Hs., Rd. abv. Tona For. Sta., km 16-17, 1700-1800 m, 28.IV.1998, A. Smetana [190]" (cSme); 3 exs.: " Taiwan, Taichung Hsien, Anmashan, 2150 m, 13. V.92, A. Smetana [ T 129]" (cSme, cAss); 3 exs.: " Taiwan, Taichung Hsien, Anmashan, 2120 m, 1. V.1990, A. Smetana [ T 36]" (cSme, cAss); 1 ex.: " Taiwan, Taoyuan Hsien, Takuanshan For., 17.IV.90, 1650 m, A. Smetana [ T 5]" (cAss); 7 exs.: " Taiwan, Hualien Hsien, Taroko N.P., Chungyangtienshi (Riv.), Waterfall, 2300 m, 10. V.1990, A. Smetana [ T 50]" (cSme, cAss); 2 exs.: " Taiwan, Hualien Hsien, Taroko N.P., Nanhushi Hut, 2200 m, 11. V.1990, A. Smetana [ T 53]" (cSme).

Description:

Body length 6.0- 7.5 mm. Habitus as in Fig. 97 . Coloration: body blackish-brown to black; elytra with well-defined reddish-yellow spot of subcircular, semi-circular, or oval shape (of the size of

the eyes or somewhat larger) near posterior margin; legs reddish to reddish-brown; antennae reddish-brown.

Head approximately as long as wide, widest across eyes ( Fig. 98 ); posterior angles weakly marked, rounded; dorsal surface with coarse and relatively dense punctation, median dorsal portion and frons with sparser punctation; interstices glossy, without microsculpture; eyes relatively large, more than half the length of postocular region from posterior margin of eyes to neck in dorsal view. Antenna as in Fig. 99 , approximately 2 mm long.

Pronotum 1.20-1.25 times as long as wide and ususally slightly (approximately 0.95 x) narrower than head; punctation similar to that of head, but somewhat sparser; midline usually narrowly impunctate, rarely punctate like lateral portions; interstices without microsculpture.

Elytra of remarkably variable length, 0.8-1.0 times as long as pronotum; submarginal line present; punctation very coarse and dense, well-defined, and arranged in more or less irregular series. Hind wings in specimens with long elytra fully developed.

Abdomen approximately as broad as (specimens with short elytra) or somewhat narrower (specimens with long elytra) than elytra; punctation of anterior impressions of tergites I-IV coarse, of remainder of tergal surfaces fine and moderately dense; interstices with very shallow microsculpture; posterior margin of tergite VII with palisade fringe.

♂: posterior margin of tergite VIII indistinctly angled in the middle ( Fig. 100 ); sternite VII with rather large median impression without pubescence, posterior margin weakly concave; sternite VIII with oblong median impression, this impression with 25-40 peg-setae, posterior excision moderately large and U-shaped ( Fig. 101 ); aedeagus approximately 1.3 mm long, ventral process separated into two long and slender lobes (ventral view), in lateral view with distinct tooth approximately in the middle ( Figs 102-104 ).

♀: posterior margin of tergite VIII obtusely angled in the middle ( Fig. 105 ); sternite VIII somewhat longer than tergite VIII, posterior margin broadly convex ( Fig. 106 ); segments IX-X not conspicuously slender; tergite IX undivided anteriorly; tergite X anteriorly truncate, of ovoid shape, and approximately 3.5 times as long as tergite IX in the middle.

Comparative notes:

This species is distinguished from all its congeners particularly by the morphology of the bilobed aedeagus, as well as by the shape and chaetotaxy of the male sternites VII-VIII. Among the Taiwanese representatives of the genus, L. bilobatum is characterised especially by the variable length of the elytra.

Etymology:

The specific epithet (Latin, adjective) refers to the distinctive shape of the ventral process of the aedeagus, which is subdivided into two long lobes.

Distribution and natural history:

Lobrathium bilobatum is apparently the most common and widespread species of the genus in Taiwan and has been collected in several provinces (Chiai, Ilan , Nantou, Hualien, Kaohsiung, Taoyuan, Taichung) at altitudes of 1700-2400 m. The material was found in moss and vegetation at the margin of ponds in an old coniferous forest, under plastic sheets covering bags of fertilizer, by sifting wet moss and leaf litter along edges of ponds, streams, and near waterfalls, and by sifting - mostly moist to wet - humus, leaf litter, and debris in various types of forests. A considerable proportion of the specimens collected in April is teneral .

Figures

Figs 97-106: Lobrathium bilobatum sp. n.: habitus (97); forebody (98); antenna (99); male tergite VIII (100); male sternite VIII (101); aedeagus in lateral and in ventral view (102-104); female tergite VIII (105); female sternite VIII (106). Scale bars: 97-99: 1.0 mm; 100-106: 0.5 mm.