Akarbatrus, Löbl, 2009

Löbl, Ivan, 2009, Akarbatrus gen. nov., an unusual Batrisitae (Coleoptera: Staphylinidae: Pselaphinae) from Sumatra, Acta Entomologica Musei Nationalis Pragae 49 (2), pp. 661-670 : 662-664

Akarbatrus gen. nov.

( Figs 1–10 )

Type species. Akarbatrus jelineki sp. nov.

Diagnosis. Head rounded triangular. Eyes situated in posterior half of head. Antenna long, club loosely 3-segmented, ultimate segment conspicuously long. Pronotum lacking tubercles, spines and antebasal foveae, with antebasal stria and pair of laterobasal foveae. Elytra lacking foveae and dorsal striae. Marginal elytral striae present. Abdomen moderately narrowed apically, with rounded apex. Abdominal tergite 1 slightly longer than tergites 2 or 3, with lateral margins rounded. Legs long. Male pronotum excavated.Aedeagus elongate, with loose, weakly attached associated sclerite and long paramere, median lobe moderately flattened, with dorsal membrane and apophyses.

Description. Length 1.35–1.75 mm. Head rounded triangular. U-shaped vertexal sulcus present or absent. Vertexal foveae small. Eyes convex, not emarginate, situated in posterior half of head. Gular carina faint. Gular foveae in a common, fovea-like depression. Maxillary palpus lacking obvious sexual characters, with segment 3 about as long as wide and segment 4 narrowed toward base and apex, with a shallow impression. Antenna 11-segmented, long, with thick scape and loosely 3-segmented club, ultimate antennomere conspicuously elongate. Pronotum with pair of laterobasal foveae, lacking tubercles and spines, with mesal depression. Elytra lacking basal and laterobasal foveae, lacking discal striae, with marginal striae on elytral flanks, with or without lateroapical cleft. Prosternum with pair of simple lateral foveae. Lateral metasternal foveae touching mid-line, about as large as anterolateral metasternal foveae. Abdomen moderately narrowed and rounded apically. Tergite 1 lacking basal sulcus, with pair of basal foveae, angular laterobasally, rounded lateroapically, with only inner marginal carinae apparent. Following tergites lacking marginal carinae. Sternite 2 with two pairs of basal foveae.

Differential diagnosis. Akarbatrus gen. nov. may be distinguished from most members of the supertribe Batrisitae by the elytra lacking foveae. The absence of elytral foveae is shared with several members of the temperate edaphic or cavernicolous ‘Amauropini’, and a few subtropical and tropical taxa, such as Amblybatrisus Chandler, 2001 , Batrisoconnus Leleup, 1975 , Batrisopsis Raffray, 1894 , Jochmansiella Leleup, 1976 , Megabatrus Löbl, 1979 , Mnia Newton & Chandler, 1989 , Mossman Chandler, 2001 , Ophelius Raffray, 1904 , and Procheilophorus Leleup, 1981 (see also LELEUP 1975, 1976b, 1981; LÖBL 1973, 1979; RAFFRAY 1894, 1908).

Akarbatrus is unique within the Batrisitae in having both reduced elytral foveae and sexually modified male pronotum. Thus, the combination of these two features provides means for a reliable identification of the new genus. Akarbatrus and Mossman are similar in their body shape and share long appendages, pronota without spines, presence of laterobasal pronotal foveae while other pronotal foveae are absent, abdominal tergites 1 lacking basal sulci and possessing only one pair of basal foveae and one pair of inner marginal carinae, and elongate and complex aedeagus with a long paramere. Akarbatrus may be readily distinguished from Mossman also by the apically moderately narrowed and rounded abdomen, while the abdomen is conical in Mossman . In addition, Akarbatrus differs from Mossman by the eyes situated in the basal half of the head and the pronotum lacking tubercles. The remaining genera listed above are not linked by any synapomorphy and each of them except members of the ‘Amauropini’ appears to be isolated within the supertribe Batrisitae (see CHANDLER 2001; LELEUP 1976b; LÖBL 1973, 1979; RAFFRAY 1894, 1908).

Etymology. The name is derived from the Indonesian word Akar, meaning root, and combined with an arbitrary abbreviation of Batrisus Aubé, 1833 , the type genus of the Batrisitae . Gender masculine.

Distribution. Indonesia: Sumatra.

Comments. All 12 specimens of Akarbatrus gen. nov. collected are males. This is possibly due to differences in phenology (females may appear later than males).

Figures

Figs. 1–4. Akarbatrus jelineki gen. nov.et sp. nov., SEM micrographs. 1–2 – head (1 – dorsal view; 2 – lateral view); 3–4 – pronotum (3 – dorsal view; 4 – lateral view).

Figs. 5–10. Akarbatrus jelineki gen. nov. et sp. nov. 5 – antennomeres 1 to 4, scale bar = 0.1 mm; 6 – pronotum in ventral view, scale bar = 0.2 mm; 7 – mesotrochanter, scale bar = 0.1 mm; 8 – metatrochanter, scale bar = 0.1 mm; 9–10 – aedeagus (9 – ventral view, 10 – lateral view; scale bar = 0.1 mm).