Baeocera hutan, Löbl, 2022

Löbl, Ivan, 2022, Supplement to the knowledge of Scaphisomatini of Sabah, Malaysia (Coleoptera: Staphylinidae: Scaphidiinae), Acta Musei Moraviae, Scientiae biologicae 107 (1 - 2), pp. 7-19 : 8-9

Baeocera hutan sp. nov.

( Figs 1 ̅4)

Type material. Holotype male, Sabah: Lahad Datu Ulu Segama forest Reserve , Danum Valley For. Centre , N 04°57.9′ E 117°48.1′, 200 m, 21.xi.2005, D. Mann, E. Slade & J. Villanuava lgt., lowland mix. dipterocarp forest. West trail area 1, FIT, OUMNH 2006­051 ( OUMNH) .

Description. Length 1.28 mm, width 0.76 mm. Head and body nearly evenly reddishbrown, elytra hardly darker than pronotum, apical abdominal segments slightly lighter than pronotum, femora and tibiae as elytra, tarsi and antennae lighter. Head with interocular distance nearly as dorsoventral eye diameter. Head, thorax and elytra lacking microsculpture. Length/width ratios of antennomeres as follows: III 20 /5: IV 20 /6: V 30 /7: VI 27 /7: VII 33 /8: VIII 27 /7: IX 36 /11: X: 37/15: XI 48 /17. Pronotal and elytral punctation even, very fine. Lateral contours of pronotum and elytra continuously, very weakly arcuate. Pronotum with anterior margin bead broadly interrupted, lateral margins sinuate in lateral view, lateral margin striae impunctate. Margin of exposed part of scutellum rounded. Elytra with lateral margins nearly parallel, lateral margins in lateral view slightly sinuate, lateral margin carinae visible in dorsal view, lateral margin striae impunctate; sutural striae starting at base, parallel, deeply impressed, curved along pronotal lobe to form basal striae extended to humeral areas, broadly separated from lateral striae; discal punctation sparse, near base with puncture intervals about 8 to 10 larger than puncture diameters. Hind wing fully developed. Hypomera and mesanepisterna appearing impunctate. Mesoventrite with mesal ridge, punctate along lateral margins. Mesepimeron about 4 times as long as large and 5 times as long as interval to mesocoxa. Median part of metaventrite nearly flat, impunctate mesally, with dense, fairly coarse punctures on posterior third and laterally smooth mesal area, bearing conspicuous, long pubescence. Lateral parts of metaventrite with few scattered extremely fine punctures. Submesocoxal line parallel, margined with row of coarse elongate punctures extended posterior the inner part of mesepimeron. Submesocoxal area about 0.02 mm long. Metanepisterna large, about 0.10 mm wide, twice as long as wide, slightly convex, with inner margin broadly rounded anteriorly, nearly straight posteriad; inner suture impunctate. Protibiae straight. Mesotibiae and metatibiae slightly bent. Ventrite I lacking striae, with row of elongate basal punctures not interrupted in middle, extended laterally behind tip of metepimeron; punctation posterior basal row very fine and sparse. Male. Protarsomeres Ito III strongly widened, bearing long tenent setae; protarsomere I wider than apex of protibia. Ventrite VI with apical lobe subtriangular, about 0.04 mm long. Aedeagus ( Figs 1 ̅4) 0.60 mm long. Median lobe and parameres strongly sclerotized, symmetrical, dorsal valves excepted. Articular process not prominent, distinct. Apical process of median lobe somewhat shorter than basal bulb, moderately inflexed, with weakly concave ventral margin, gradually narrowed apically, tip acute in lateral view, obtuse in dorsal view. Parameres robust, gradually narrowed apically in dorsal view, widened apical in lateral view, with broadly rounded apex. Internal sac with complex sclerites, lacking spinose and denticulate structures, with apical section of ejaculatory duct wide, weakly membranous, extruded in repos.

Etymology. The species epithet is a noun meaning "forest̏ in Malay.

Differential diagnosis. This species is unique in having broadly interrupted pronotal bead. Therefore, it is placed in Baeocera tentatively (the mouth­parts and thorax of the unique available specimen were not dissected). In addition, its aedeagal characters are unusual, in particular by the structure of the internal sac and the asymmetrical valves of the median lobe. The internal sac lacking a flagellar guide sclerite and possessing a membranous ejaculatory duct extruded in repos is shared with the Chinese B. xichangana Löbl, 1999 . It differs notably from B. xichangana by the not prominent articular process, the two asymmetrical dorsal valves, and the much shorter, robust parameres. Both species are also very distinct in external characters, in particular by their body­shape and size ( B. xichangana is 2.0̅ 2.15 mm long).

Remarks. As to the Sabah species, only B. barbara Löbl, 1990 and B. doriae (Pic, 1920) share the wide metanepisterna. These two species have asymmetrical aedeagus and may be easily distinguished by their external characters. The antitheses 7 and 8 have been inversed in key to the Sabah Baeocera given by LÖBL & SMETANA (2021): the thesis 6 (Metanepisternum fused, ...) should lead to ̤ 8.

Figures

Figs 1-7. 1-4 ̅ Baeocera hutan sp. nov.; 1, 2 ̅ Aedeagus in dorsal and lateral views, scale = 0.2 mm; 3, 4 ̅ Internal sac in dorsal and lateral views, scale = 0.1 mm. 5-7 ̅ Pseudobironium irregulare sp. nov.; 5, 6 ̅ Aedeagus in dorsal and lateral views, scale = 0.1 mm; 7 ̅ Internal sac in dorsal view, scale = 0.1 mm.