Liopygus occidentalis, Lackner & Vienna, 2017

Lackner, Tomáš & Vienna, Pierpaolo, 2017, Histeridae of Socotra (Coleoptera: Histeroidea), Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 57, pp. 55-76 : 61-64

Liopygus occidentalis sp. nov.

( Figs 14–22 )

Type material. HOLOTYPE: J, side-mounted on a triangular mounting card, genitalia extracted, dismembered and glued to the same mounting card as the specimen, with the following labels: ‘ YEMEN SOCOTRA Island / Skant area , 1300-1500 m / N 12°34′33″, E 54°01′31″ / 31.i.-1.ii.2010, L. Purchart lgt.’ [printed]; followed by: ‘ Liopygus occidentalis / sp.nov . HOLOTYPUS / det.T.Lackner & P.Vienna / 2017’ [red label,handwritten] ( NMPC). ALLOTYPE: ♀, glued on its back on a triangular mounting card, with the following labels: ‘ YEMEN, Socotra Island / Al Haghier Mts. / Scant Mt. env. / 12°34.6′N, 54°01.5′E, 1450 m / Jiří Hájek leg. 12-13.xi.2010 ’ [printed]; followed by: ‘ Liopygus occidentalis / sp. nov . ALLOTYPUS / det. T. Lackner & P. Vienna / 2017’ (red label, hand-written) ( NMPC). PARATYPE: YEMEN: SOCOTRA: J, side-mounted on a triangular mounting point, genitalia extracted, dismembered and glued to the same mounting card as the specimen, with labels identical to those of the allotype ( TLCM).

Description. Body ( Figs 14–15 ). PEL = 2.60–2.80 mm; APW = 0.80–0.90 mm; PPW = 1.30–1.50 mm; EW = 1.40–1.60 mm; EL = 1.60–1.80 mm, flattened, elongate, color light castaneous-brown.

Head. Eyes strongly flattened, not visible from above. Frontoclypeal area finely punctate, slightly depressed, traces of supraorbital striae visible above eye, other striae absent. Labrum flattened, rectangular, each mandible with large triangular subapical tooth. Maxillary palpi very prominent, terminal maxillary palpomere longer than mandible itself, visible from dorsal view. Mentum large, quadrate, labial palpi thick, terminal labial palpomere rather thick, its width approximately half its length. Submentum considerably smaller than mentum, triangular. Antennal scape massive, its length approximately equals to that of antennal funicle. Pedicel thickened, approximately as long as antennomeres III and IV together; club large, oval, setose, intersegmental sutures visible.

Pronotum almost quadrate, along midline slightly broader than long, anterior angles strongly projected, acute. Marginal pronotal stria very thin, present only on apical angles and behind head; lateral pronotal stria slightly distanced from pronotal margin, parallel to it, terminating anteriorly on anterior pronotal margin. Pronotal disc impunctate; pronotal hypomeron asetose.

Elytra impunctate, approximately twice as long as broad, lateral epipleura bistriate, striae thin, complete; subhumeral elytral striae absent, humeral elytral stria very thin, bifurcate. Elytral disc only with scattered microscopic punctation, dorsal elytral striae 1–4 complete, stria 5 almost complete, shortened basally. Sutural elytral stria absent.

Propygidium broad, approximately 2.5 times as broad as long, with scattered deep ocellate punctures, separated by approximately 1.5–2.0 times their diameter. Pygidium in basolateral angles with two shallow depressions, each with deep fossa; pygidial surface basally with several vague shallow punctures, otherwise impunctate.

Prosternal lobe ( Fig. 15 ) large, rounded, with scattered microscopic punctation; marginal prosternal stria present, weakened to absent on apex. Carinal prosternal striae present as very vague rudiments on prosternal apophysis; lateral prosternal striae double, deeply impressed, subparallel and bisinuate; surface of composite ventral plate laterad to it with large deep ocellate punctures. Mesoventrite ( Fig. 15 ) anteromedially deeply inwardly arcuate, marginal mesoventral stria present, thin, disc glabrous. Metaventrite ( Fig. 15 ) flattened, with scattered microscopic punctation, lateral metaventral stria long, almost straight, nearly reaching metacoxa. Lateral disc of metaventrite with several large deep ocellate punctures; metanepisternum covered by elytral epileuron, not visible.

Abdominal ventrite I ( Fig. 15 ) with scattered microscopic punctation, striate laterally.

Legs. Protibial spur prominent; protarsal groove deep; outer protibial margin with 5 rather prominent teeth topped by tiny denticle; teeth 2–3 widely separated; mesotibia on outer margin with two widely spaced short denticles, two additional longer denticles situated near tarsal insertion; outer margin ventrally with sparse row of tiny widely spaced denticles. Metatibia slightly longer than mesotibia, otherwise similar to it, except for there is only a single denticle on outer margin medially instead of two.

Male genitalia. Sternite VIII ( Figs 16–17 ) divided into two parts; tergite VIII and sternite VIII not fused ( Fig. 18 ). Tergite IX ( Fig. 19 ) divided into two parts; tergite X ( Figs 19–20 ) small, its basal part wedged between the divided parts of tergite IX; sternite IX ( Figs 19–20 ) or spiculum gastrale apically divided into two ‘tails’, pointed basally. Aedeagus ( Fig. 21 ) tube-like, median lobe protruding from tegmen; phallobase ( Fig. 22 ) approximately 1.5 times shorter than fused parameres.

Differential diagnosis. The Socotran species strongly resembles the species Liopygus decemstriatus (Motschulsky, 1863) from Sri Lanka. It can, however, be readily distinguished from it based on the following characters: both dorsal elytral striae 2 and 4 are complete in the Socotran species (incomplete in L. decemstriatus ); dorsal elytral stria 5 reaches even further basally in the Socotran species; propygidium of the Socotran species is entirely punctate (only partly punctate in L. decemstriatus ); pygidium of the Socotran species is punctate only in its proximal part between the two fossa (pygidium of L. decemstriatus is punctate entirely).

Comments. The genus Liopygus Lewis, 1891 contains 16 described species distributed exclusively in southeast Asia ( MAZUR 2011).All Liopygus species , as far as known, live under bark, preying on small arthropods ( DESBORDES 1919). Although DESBORDES (1919) published a key to the species of the genus, difficulties using it for species determination were voiced by GOMY (2006), who described the only species of Liopygus after the World War II. The discovery of a member of Liopygus in Socotra Archipelago, considerably far from the distribution area of the genus is highly interesting, and we advocate a revision of the genus.

Etymology. Specific epithet, the Latin adjective ‘ occidentalis ’ (= western), refers to the disjunct geographical location of the new species.

Distribution. Endemic to Socotra Island, so far known only from the highest part of Hagher mountains.

Figures

Figs 14–15. Liopygus occidentalis sp. nov. 14 – habitus in dorsal view; 15 – habitus in ventral view.

Figs 16–22. Liopygus occidentalis sp. nov., male genitalia. 16 – sternite and tergite VIII, ventral view; 17 – ditto, dorsal view; 18 – ditto, lateral view; 19 – tergites IX–X, dorsal view, spiculum gastrale (sternite IX), ventral view; 20 – tergites IX–X and spiculum gastrale (sternite IX), lateral view; 21 – aedeagus, dorsal view; 22 – ditto, lateral view.