Lathrobium (Lathrobium) utriculatum, Assing, 2010

Assing, Volker, 2010, On the Lathrobiina of Taiwan (Coleoptera: Staphylinidae: Paederinae), Beiträge Zur Entomologie = Contributions to Entomology 60 (2), pp. 301-361 : 310-312

Lathrobium (Lathrobium) utriculatum sp. n. ( Figs 24-31 )

Type material:

Holotype ♂: " Taiwan, Kaohsiung Hsien, Peinantashan trail, ridge at 2800 m, 3.VII.1993, A. Smetana [ T134 ] / Holotypus ♂ Lathrobium utriculatum sp. n., det. V. Assing 2010" (cSme).

Paratypes: 2 ♂ ♂, 3 ♀ ♀: same data as holotype (cSme, cAss) .

Description

Body length 4.1-5.0 mm; habitus as in Fig. 24 . Externally highly similar to L. involutum , except for smaller average body size and the pronounced microsculpture on the head ( Fig. 25 ). Reliably distinguished only based on the primary and secondary sexual characters:

♂: sternite VII truncate posteriorly, pubescence not distinctly modified ( Fig. 26 ); sternite VIII only indistinctly oblong, posterior excision in somewhat asymmetric position, small, its depth approximately 1/10 the length of sternite ( Fig. 27 ); aedeagus small, approximately 0.65 mm long, with slender ventral process, long and S-shaped (lateral view) dorsal plate, and internal structures of distinctive shape ( Fig. 28 ).

♀: tergite VIII with posterior margin weakly convex ( Fig. 29 ), latero-ventral parts extended, but slightly less so than in L. involutum , meeting ventrally, but not overlapping; sternite VIII distinctly oblong, approximately 1.30-1.35 times as long as broad, much longer than tergite VIII, and distinctly produced posteriorly ( Fig. 30 ); tergite X more than twice as long as tergite IX in the middle ( Fig. 31 ).

Comparative notes:

Based on the similar external and the secondary sexual characters, as well as particularly on the synapomorphically derived morphology of the aedeagus, L. utriculatum belongs to the L. involutum group. From other species of this group, it is reliably distinguished only by the shape and internal structures of the aedeagus.

Etymology:

The specific epithet (adjective derived from the Latin noun uter: tube, hose) refers to the shape of the basal internal structure of the aedeagus, which somewhat resembles a bagpipe or a wineskin.

Distribution and natural history:

As can be inferred from the restricted distributions of the closely related congeners, as well as from the adaptive reductions of pigmentation, eye size, wings, and palisade fringe, the species is probably endemic to the Peinantashan range in Kaoshiung Hsien, central Taiwan. The type specimens were sifted from moss and other debris around bases of trees in a coniferous forest with bamboo undergrowth at an altitude of 2800 m. One of the dissected females had a mature egg in the ovaries.

Figures

Figs 24-31: Lathrobium utriculatum sp. n.: habitus (24); forebody (25); male sternite VII (26); male sternite VIII (27); aedeagus in lateral view (28); female tergite VIII (29); female sternite VIII (30); female tergites IX-X (31). Scale bars: 24-25: 1.0 mm; 26-27, 29-31: 0.5 mm; 28: 0.2 mm.