Leptomastax minutissima, Jałoszyński, 2024

Jałoszyński, Paweł, 2024, A new species of Leptomastax Pirazzoli in Israel (Coleoptera: Staphylinidae: Scydmaeninae), Zootaxa 5481 (3), pp. 391-396 : 392-394

Leptomastax minutissima sp. n.

( Figs 1‒13 )

Type material. Holotype: ( ISRAEL): ♂, two labels: “ISRAEL: Galilea / Eilon, N. Betzel / valley, 20.IV.1982 / Löbl, Bes. nr. 13a” [white, printed], “ LEPTOMASTAX / minutissima m. / P. Jałoszyński, '24 / HOLOTYPUS” [red, printed] ( MHNG).

Diagnosis. Body extremely small, below 1.2 mm; eyes lacking; subocular and elytral macrosetae lacking; prosternum with two large lateral patches of modified setae; anterior region of mesoventral process much wider than its posterior intermesocoxal region; elytral rows of punctures irregular, subhumeral and marginal rows lacking; male with U-shaped impression with distinct lateral margins on posterior 1/3 of metaventrite; aedeagus with simple (i.e., unbranched) and nearly straight endophallus; each paramere with evenly rounded subapical and apical margin and with pointed apex directed mesally.

Description. Body of male ( Fig. 1 ) strongly elongate, strongly flattened, yellowish brown. BL 1.13 mm.

Head ( Fig. 2 ) broadest near middle, eyeless, HL 0.15 mm, HW 0.28 mm; vertex and frons together slightly more than twice as wide as long; dorsal postmandibular impressions distinct; subocular (sensu Castellini (1994)) macrosetae absent, vertexal macrosetae (= temporo-occipitale of Castellini) present. Dorsum of head and genae ( Fig. 5 ) impunctate. Antenna ( Fig. 3 ) slender, AnL 0.50 mm, scape as long as antennomeres 2–5 together, pedicel 1.3 times as long as broad, antennomeres 3–10 each transverse (3 strongly, 10 weakly so), antennomere 11 nearly as long as 9–10 combined, 1.8 times as long as broad.

Labial palps moderately long, palpomere 2 about twice as long as broad, palpomere 3 setiform, slightly longer than 2.

Pronotum ( Fig. 2 ) subtrapezoidal, broadest near anterior fourth; PL 0.30 mm, PW 0.28 mm. Anterior margin evenly and weakly rounded; lateral margins strongly rounded in anterior third and nearly straight in posterior half; posterior corners strongly obtuse-angled; posterior margin weakly and evenly rounded. Pronotal disc impunctate and asetose. Prosternum ( Fig. 5 ) with pair of large anterolateral patches of modified, strongly flattened and broadened scale-like setae and narrow row of similar setae along median portion of anterior margin.

Mesoventrite ( Figs 8‒9 ) with scale-like setae on procoxal rests and elongate flattened setae on mesoventral process. Metaventrite ( Figs 8‒9 ) with scale-like setae filling postmesocoxal foveae and with elongate flattened setae evenly distributed on remaining surface. Posterior third of metaventrite with median U-shaped impression.

Elytra ( Fig. 4 ) together oval and strongly elongate, broadest near middle; EL 0.68 mm, EW 0.35 mm, EI 1.93; humeral region strongly narrowing towards prothorax; lateral margins weakly rounded; apices separately rounded. Each elytron with sutural and humeral row of punctures, lacking subhumeral and marginal rows; punctures distinct but unevenly distributed, so that rows are somewhat irregular. Macrosetae (and setiferous punctures) in humeral and apical regions lacking. Elytra asetose and outside rows of punctures impunctate.

Legs ( Figs 1 , 9 ) moderately long and slender, unmodified; each mesocoxa with two macrosetae.

Abdomen ( Fig. 8 ) with regular setae almost evenly covering all exposed sternites.

Aedeagus ( Figs 10‒13 ) slender, AeL 0.18 mm; median lobe in ventral view gradually narrowing towards subtriangular apex, in lateral view distal region nearly straight; sclerotized endophallus unipartite, tubular and unbranched, nearly straight; parameres with evenly rounded outer margins in subapical and apical regions, apex of each paramere pointed and directed mesally.

Female. Unknown.

Distribution. Northern Israel.

Etymology. The specific adjective minutissima refers to the smallest body among all known species of Leptomastax .

Remarks. This is the smallest known species of Leptomastax ; it can be easily identified by the slender, strongly elongate elytra, reduced and irregular elytral rows of punctures, lack of eyes, and aedeagal structures. The simple, unbranched endophallus in L. minutissima resembles that of L. cretica Meybohm (in Assing et al. (2019), fig. 149), but the latter species is much larger (BL 1.73‒1.83 mm) and has large eyes, each composed of “about 14 ommatidia” ( Assing et al. 2019). The apical region of median lobe and the endophallus in L. cretica in lateral view are strongly curved (nearly straight in L. minutissima ), and the parameral apices in ventral view in L. cretica are rapidly bent mesally (evenly and gradually curved in L. minutissima ).

Notes containing detailed collecting data for the studied specimen have been lost; is is only known that most specimens taken during the Löbl-Besuchet 1982 fieldwork in Eilon come from sifted oak leaf litter (email from Ivan Löbl dated 18/06/2024).

Figures

FIGURES 1–4. Leptomastax minutissima sp. n., holotype male. Dorsal habitus (1); head, pronotum and elytral base in dorsal view (2); left antenna in dorsal view (3); elytra in dorsal view (4).

FIGURES 5–7. Leptomastax minutissima sp. n., holotype male. Head, prothorax and anterior region of mesothorax in ventral view (5); mouthparts in ventral view (6); left labial palp in ventral view (7).

FIGURES 8–9. Leptomastax minutissima sp. n., holotype male. Pterothorax and base of abdomen in ventral view (8); right mesocoxa and surrounding areas in ventral view (9).

FIGURES 10–13. Leptomastax minutissima sp. n., holotype male. Aedeagus in ventral (10, 12) and lateral (11, 13) views.