Paraneseuthia libanica, Jałoszyński, 2020

Jałoszyński, Paweł, 2020, Four new Palaearctic, Australian and Oriental species of Paraneseuthia Franz (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 4858 (2), pp. 231-240 : 232-234

Paraneseuthia libanica sp. n.

( Figs 1–8 )

Type material. Holotype: LEBANON: ♂, two labels : “ LIBAN - 1975 / Damour 24 III / 1b / BESUCHET” [white, printed and handwritten]; “ PARANESEUTHIA / libanica m. / P. Jałoszyński, 2020 / HOLOTYPUS ” [red, printed] ( MHNG) . Paratypes (17 exx., incl. 2 disarticulated): 3 ♂♂, 5 ♀♀, and 9 exx. of unknown sex, same data as for holotype (cPJ, MHNG) .

Diagnosis. Body conspicuously small (BL <0.8 mm) and slender, covered with short and recumbent setae; eyes in both sexes small and weakly convex; head, protibia and metaventrite in male unmodified; aedeagus with asymmetrical distal half and a pair of lateral apical projections directed distodorsad, with diaphragm oblique in relation to the long axis of aedeagus and situated in subapical region.

Description. Body of male ( Fig. 1 ) slender and moderately convex, dark brown with slightly lighter appendages, especially antennae and maxillary palps, setae light brown; BL 0.74 mm.

Head ( Figs 1–2 ) broadest at inconspicuous, small and weakly convex eyes, HL 0.09 mm, HW 0.15 mm; vertex and frons confluent, convex at middle and slightly impressed at sides; supraantennal tubercles barely discernible. Punctures on vertex and frons relatively large but with diffuse margins, so that cuticle appears uneven; setae short, sparse and recumbent. Antennae ( Figs 1–2 ) short but slender, with distinctly delimited trimerous club, AnL 0.28 mm, antennomeres I–II each elongate, III about as long as broad, IV weakly elongate, V–VI each about as long as broad, VII–X each transverse, XI not broader than X, about as long as IX–X together, about 1.8× as long as broad.

Pronotum ( Figs 1, 3 ) subquadrate with all margins rounded, broadest near anterior third; PL 0.20 mm, PW 0.20 mm; posterior and anterior corners obtuse-angled and blunt; pronotal base with small but distinct median pit and two pairs of similarly small and distinct lateral pits, of which the lateralmost pair is developed as elongate impressions. Punctures on pronotal disc fine and inconspicuous; setae short, sparse and recumbent.

Elytra ( Fig. 1 ) together oval, broadest between middle and anterior third and relatively strongly narrowing posterad, evenly convex; EL 0.45 mm, EW 0.30 mm, EI 1.50; humeral calli and basal impressions lacking; apices separately rounded. Punctures on elytra inconspicuous, dense but small and diffuse; setae sparse and recumbent. Hind wings absent.

Legs moderately long and slender; unmodified, all tibiae nearly straight.

Aedeagus ( Figs 5–8 ) moderately slender, AeL 0.24 mm; median lobe in ventral view with symmetrical basal half and asymmetrical distal half; apex with a pair of elongate projections directed distodorsad; diaphragm oblique in relation to the long axis of aedeagus, situated in subapical region; parameres slender, each with slightly broadened apical region, lacking apical setae.

Female. Externally indistinguishable from male. BL 0.66–0.71 mm; HL 0.08–0.09 mm, HW 0.15 mm, AnL 0.25 mm; PL 0.20 mm, PW 0.21–0.23 mm; EL 0.38–0.43 mm, EW 0.28–0.30 mm, EI 1.36–1.55.

Distribution. West-central Lebanon.

Etymology. After the Latinized country name.

Remarks. Paraneseuthia libanica is the second species of this genus known to occur in the Mediterranean basin, far away from all remaining congeners that inhabit sub-Himalayan India, SE Asia, Far East, New Guinea, Australia and Fiji. Both western Palaearctic species, i.e., the Turkish P. meybohmi Jałoszyński, 2015 , and the Lebanese P. libanica , have small (0.7–0.8 mm), relatively slender and convex adults, and share the same form of the aedeagus. The latter is of a unique shape, not known in any other group of species within this genus. The diaphragm, normally situated in the sub-basal or submedian region of the median lobe and parallel to its long axis, in P. meybohmi and P. libanica is shifted toward the subapical region and situated on a step-wise ‘platform’ oblique or almost perpendicular in relation to the long axis of the median lobe. Aedeagi of both species also have asymmetrical apices, are curved in lateral view, and have parameres lacking apical setae. Paraneseuthia libanica has smaller eyes than P. meybohmi , a different shape of the pronotum, and a clearly different shape of the apical region of the aedeagus (with a pair of elongate lateral projections, lacking in P. meybohmi ).

Morphological structures of the head and thorax were compared in detail for Far Eastern (Japanese and Russian) and SE Asian groups of Paraneseuthia that markedly differ in body forms and genital structures. These groups were found to include congeneric species, as their cephalic and ventral thoracic character states were demonstrated to be the same ( Jałoszyński 2010). A similar morphological study was carried out for the sub-Himalayan P. loebli Jałoszyński, 2015 , with similar conclusions ( Jałoszyński 2015). Paraneseuthia meybohmi , the first known Western Palaearctic species, was not available in a sufficient number of specimens to allow for disarticulations. Among specimens of P. libanica , two males deposited at MHNG were found already disarticulated and mounted in euparal by the collector of the type series, Claude Besuchet. Ventral structures of the head, pro- and pterothorax of one of these specimens are illustrated in Figs 2–4 . Apart from the unusually slender body of P. libanica , this species does not show any important differences in relation to its previously studied relatives. The only major structure that was found variable within the genus is the pair of procoxal rests on the anterior region of the mesoventrite. In Far Eastern (Japanese) species, the rests are not demarcated posteriorly. In SE Asian species each procoxal rest has a sharply marked posterior carina, which originates at the mesoventral intercoxal process, near its median region, runs laterad, and is arcuate, connecting to the mesal corner of the mesanepisternum. In the sub-Himalayan P. loebli , the procoxal rests are demarcated posteriorly by a transverse carina parallel to the anterior margin of mesoventrite, the carina reaches only to middle between the mesoventral intercoxal process and the mesanepisternum; and the lateral portion of mesoventrite, between the procoxal rest and mesanepisternum + mesepimeron is occupied by a large pit filled with setae. In the Mediterranean P. libanica , the procoxal rests on the mesoventrite are posteriorly demarcated by a sharp carina which extends laterad nearly to mesanapisterna (it is obliterated shortly before reaching them), the carina is parallel in relation to the anterior mesoventral margin, and the mesoventrite lacks lateral pits. These differences in mesothoracic structures are not sufficient to divide the genus into subgenera, especially that Paraneseuthia is the most diverse genus of Eutheiini in terms of body shapes, male secondary dimorphic structures, and especially the aedeagus. Certainly the Mediterranean species form a distinct group, differing from all other congeners in the structure of the aedeagus, but not in any other, taxonomically important characters.

Figures

FIGURES 1–8. Paraneseuthia libanica sp. n., male. Dorsal habitus (1); head in ventral view (2); prothorax in ventral view (3); pterothorax in ventral view (4); aedeagus in ventral (5, 7) and lateral (6, 8) views.