Araneibatrus spinosus, Yin, Zi-Wei, Jiang, Ri-Xin & Steiner, Helmut, 2016

Yin, Zi-Wei, Jiang, Ri-Xin & Steiner, Helmut, 2016, Revision of the genus Araneibatrus (Coleoptera: Staphylinidae: Pselaphinae), Zootaxa 4097 (4), pp. 475-494 : 493-494

Araneibatrus spinosus , new species

( Figs 3 B, 4F, 5F, 7B, 8F, 9F, 11G–I, 12, 13C–D)

Type material. Holotype: male: ‘Tham Chom Ong (F47-120-001), 20°45′06.9″N, 101°46′42.7″E, Xai District, Oudomxay, Laos, 28.i.2010, W. Zillig leg.’ ( SNUC). Paratype: 1 male: ‘Tham Houay Soy (F47-120-015), 20°45′37″N, 101°45′50″E, Ban Houay Soy, Oudomxay Prov., Laos, 2014. xii.29, H. Steiner & I. Ermarkova leg.’ ( SNUC).

Diagnosis. Body length 2.51–2.54 mm. Vertex lacking mediobasal carina and postantennal carinae; clypeus elongate, about one-third of total head length. Pronotum lacking median longitudinal and antebasal sulci; lacking dorsal carinae and discal tubercles, with distinct antebasal spines. Elytra lacking discal striae; anterolateral margins faintly emarginate. Metaventrite with narrow notch at middle of posterior margin. Tergite IV only with two basolateral foveae. Sternite IV lacking mediobasal foveae, with six basolateral foveae. Male with unmodified antennal clubs, metaventrite densely setose submedially, meso- and metatrochanters spinose. Aedeagus with stout basal capsule.

Description. Male ( Fig. 3 B). Length 2.51–2.54 mm, body extremely elongate, uniformly reddish-brown, mouth parts, tibiae and tarsi lighter in color.

Head ( Fig. 4 F) distinctly longer than wide, HL 0.51–0.52 mm, HW 0.45 mm, finely punctate; vertex lacking median carina, lacking lateral postantennal carinae; clypeus unusually long, as long as one-third of total head length; antennal clubs loosely formed by three apical elongate antennomeres, unmodified, antennomere XI evenly narrowed at apical one-third. Pronotum ( Fig. 4 F) as wide as head and longer than wide, PL 0.53 mm, PW 0.45– 0.46 mm; disc finely punctate, lacking median longitudinal sulcus and transverse antebasal sulcus, lacking dorsal carinae and discal tubercles, with distinct antebasal spines. Elytra ( Fig. 5 F) longer than wide, EL 0.81–0.83 mm, EW 0.71–0.73 mm, lacking discal striae, anterolateral margins faintly emarginate. Mesoventrite ( Fig. 7 B) with lateral foveae separated from median foveae. Metaventrite ( Fig. 7 B) densely setose in submedian area; posterior margin with narrow notch at middle. Mesotrochanter with long, straight ventral spine; metatrochanter with small, curved ventral spine. Tergite IV ( Fig. 8 F) with inner marginal carinae oblique, extending to apical two-thirds of tergal length; basal impression complete, with two basolateral foveae at lateral ends of impression. Sternite IV ( Fig. 9 F) lacking mediobasal foveae, with six basolateral foveae. Length of aedeagus ( Fig. 11 G–I) 0.40 mm, median lobe with stout basal bulb and large foramen; its distal portion spine-like, narrowed apically; dorsal lobe shorter than median lobe, narrowed from base toward apex.

Female. Unknown.

Comparative notes. The new species is most similar to A. pubescens by sharing the extremely elongate body, antennae, and legs, ventrally spinose meso- and metatrochanters, and lack of the median and antebasal sulci on the pronotal disc. It can be readily separated from A. pubescens by the presence of distinct antebasal spines on the pronotal disc, and a much stouter form of the aedeagus. Within the genus Araneibatrus, A. spinosus possesses the smallest number of foveae on the abdomen, and uniquely lacks the mediobasal foveae on the sternite IV.

Collecting environment. Descriptions of Tham Chom Ong (i.e., Chom Ong Cave) ( Fig. 13 C) can be found in Dreybrodt & Laumanns (2010, 2011). The paratype from Tham Houay Soy ( Fig. 13 D) was caught in a hall just before the boulder slope of the resurgence entrance. The hall is dry, with a lot of guano and bats.

Distribution. Northern Laos: Oudomxay ( Fig. 12 ).

Etymology. The specific epithet indicates the presence of a pair of distinct antebasal spines on the pronotum.

Figures

FIGURE 3. Dorsal habitus of Araneibatrus species. A. A. pubescens, male. B. A. spinosus, male. Scales: 0.5 mm.

FIGURE 4. Head dorsum and pronotum of Araneibatrus species. A. A. callissimus. B. A. cellulanus. C. A. grossepunctatus. D. A. cf. gracilipes. E. A. pubescens. F. A. spinosus. Scales: 0.2 mm.

FIGURE 5. Right elytron of Araneibatrus species. A. A. callissimus. B. A. cellulanus. C. A. grossepunctatus. D. A. gracilipes. E. A. pubescens. F. A. spinosus. Scales: 0.2 mm.

FIGURE 7. Meso- and metaventrite of Araneibatrus species. A. A. pubescens. B. A. spinosus. Scales: 0.2 mm.

FIGURE 8. Tergite IV of Araneibatrus species. A. A. callissimus. B. A. cellulanus. C. A. grossepunctatus. D. A. gracilipes. E. A. pubescens. F. A. spinosus. Scales: 0.2 mm.

FIGURE 9. Sternites III and IV of Araneibatrus species. A. A. callissimus. B. A. cellulanus. C. A. grossepunctatus. D. A. gracilipes. E. A. pubescens. F. A. spinosus. Scales: 0.2 mm.

FIGURE 11. Aedeagus of Araneibatrus species (A, D, G. in ventral view. B, E, H. in lateral view. C, F, I. in dorsal view). A – C. A. gracilipes. D – F. A. pubescens. G – I. A. spinosus. Scales: 0.2 mm.

FIGURE 12. Distribution of Araneibatrus species.

FIGURE 13. Collecting environment of Araneibatrus species. A, B. A living A. grossepunctatus wandering on the cave floor. C, D. Passages inside Tham Chom Ong (C) and Tham Houay Soy (D), where two specimens of A. spinosus were collected.