Lathrobium bihamulatum, Assing, 2013

Assing, Volker, 2013, On the Lathrobium fauna of China V. New species and additional records from Yunnan (Coleoptera: Staphylinidae: Paederinae), Beiträge Zur Entomologie = Contributions to Entomology 63 (1), pp. 53-128 : 115-116

4.6 The L. bihamulatum species group

4.6.1 Lathrobium bihamulatum sp. n.

(Figs 302-307, Map 8 )

Type material:

Holotype ♂: “ CHINA: Yunnan [C07-19], Dehong Dai Aut. Pref., mountain range 31 km E Luxi [= Mangshi ], 2280 m, 24°29'31"N, 98°52'58"E, secnd. pine forest with old decid. trees, litter sifted, 3.VI.2007, A. Pütz / Holotypus ♂ Lathrobium bihamulatum sp. n. det. V. Assing 2013” (cAss).

Etymology:

The specific epithet is an adjective composed of the Latin prefix bi- (two) and an adjective derived from the diminutive of the Latin noun hamus (hook). It alludes to the pair of hook-like apical internal structures of the aedeagus.

Description:

Species of intermediate size and very slender habitus (Fig. 302); body length 8.5 mm; length of forebody 3.8 mm. Coloration: body brown with reddish-brown elytra; legs and antennae dark-reddish.

Head (Fig. 303) approximately as broad as long; punctation moderately coarse and moderately dense; interstices with shallow microreticulation. Eyes small, approximately 0.25 times as long as postocular region and composed of approximately 50 small ommatidia. Antenna 2.5 mm long.

Pronotum (Fig. 303) approximately 1.3 times as long as broad and 1.02 times as broad as head; punctation similar to that of head; impunctate midline moderately broad; interstices without microreticulation.

Elytra (Fig. 303) 0.53 times as long as pronotum and slen- der, only as broad as pronotum; punctation fine and relatively sparse. Hind wings completely reduced.

Abdomen long and slender, aproximately 1.2 times as broad as elytra; punctation moderately fine, dense on tergites III-VI, somewhat sparser on tergites VII and VIII; interstices with distinct microsculpture; posterior margin of tergite VII without palisade fringe.

♂: protarsomeres I-IV strongly dilated; tergite VIII approximately as long as broad, posterior margin weakly angled in the middle; sternites III-VI unmodified; sternite VII (Fig. 304) strongly transverse and with shallow postero-median impression, pubescence not distinctly modified, posterior margin broadly and weakly concave, more distinctly concave in the middle, anterior margin with minute, almost completely reduced median process; sternite VIII (Fig. 305) distinctly transverse and moderately asymmetric, pubescence weakly modified, setae somewhat denser near posterior margin, middle of postero-median impression without setae, posterior margin asymmetrically bisinuate; aedeagus (Fig. 306) 1.3 mm long, of conspicuous morphology, apical structures of internal sac distinctly extending beyond apex of ventral process; ventral process smoothly and distinctly curved, slender, and apically acute; dorsal plate conspicuously long, apical portion lamellate and distinctly sclerotized, basal portion much longer than apical portion, lamellate, and distinctly sclerotized; internal sac with approximately five strongly sclerotized spines of different sizes and shapes (Fig. 307) and with conspicuous pair of hookshaped apical structures.

♀: unknown.

Comparative notes:

Lathrobium bihamulatum does not seem to have closer affiliations to any of the other species groups recorded from Yunnan. It is characterized by a slender body, particularly the slender elytra (not broader than pronotum; unique among Lathrobium from Yunnan), the slender abdominal tergite VIII, the asymmetrically bisinuate posterior margin of the male sternite VIII (unique among Lathrobium from Yunnan), and by the conspicuous morphology of the aedeagus (apical portion of internal sac strongly extending beyond apex of ventral process; long dorsal plate with a remarkably long and distinctly sclerotized basal portion; shapes of internal structures: presence of sclerotized spines of different shapes and sizes, and an additional conspicuous pair of apical structures).

Distribution and natural history:

The type locality is situated in the Ertaipo Shan to the east of Mangshi ( Map 8 ). The holotype was sifted from leaf litter in a secondary pine forest with interspersed old deciduous trees at an altitude of 2280 m, together with L. squamosum .

Figures

Map 8: Distribution of the species of the L. bihamulatum (filled star) and the L. desectum (open symbols) groups: L. bihamulatum (black star); L. abscisum (white circles); L. desectum, L. sectum, L. amputatum, and L. resectum (all white triangles).