Clidicus minilankanus, Jałoszyński, 2020

Jałoszyński, Paweł, 2020, Clidicus minilankanus sp. n., with notes on remaining Sri Lankan Clidicus species (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 4718 (1), pp. 87-94 : 88-93

Clidicus minilankanus sp. n.

( Figs 1–2 , 7 , 13 , 18–21 )

Material studied. HOLOTYPE: ♂: SRI LANKA, with three labels: “[ SRI LANKA] / Western Prov. , / Keg- alle distr. / Salgala For. Resv.” [pink, printed], “ 17. ix. 2016 / Sk. Yamane leg. / ex leaf litter / general coll.” [pink, printed], “ Clidicus / minilankanus m. / HOLOTYPUS, P. Jałoszyński, 2019 ” [red, printed] ( EUMJ) . PARATYPES (8 exx.): 3 ♂♂, 5 ♀♀, same data as for holotype ( EUMJ, cPJ) .

Diagnosis. Body length <4 mm; pronotum in dorsal view subquadrangular and distinctly flattened, with shallow and diffuse subtriangular posteromedian impression, with posterior ‘collar’ reduced to barely discernible short median stripe dorsally demarcated from disc by shallow biarcuate transverse groove; elytra shield-shaped, broadest just behind distinct, obtuse-angled humeri; male protrochanter modified, with anteroventral subtriangular projection; aedeagus symmetrical, broadest near base, with apices of parameres projecting distad beyond apex of median lobe, strongly curved in lateral view; sperm pump long and slender, with shallow distal and proximal funnels.

Description. Body of male ( Fig. 1 ) relatively stout, distinctly flattened, BL 3.75–3.83 mm (mean 3.79 mm); cuticle glossy, pigmentation uniformly light to dark brown, setae yellowish.

Head ( Fig. 7 ) subtrapezoidal, broadest just in front of posterior margins of tempora, HL 0.65 mm, HW 1.00– 1.03 mm (mean 1.01 mm); tempora in dorsal view 3 times as long as eyes, nearly straight and strongly divergent posterad, their posterolateral portions subtriangular and strongly projecting; vertex with short, shallow and diffuse subtriangular posteromedian impression bearing pair of distinct posterior pits marking sites where dorsal tentorial arms are fused with dorsal wall of head. Sides of vertex and frons evenly convex, frons convex also between weakly elevated supraantennal tubercles; clypeus transverse and weakly convex, demarcated from frons by deep and distinct frontoclypeal groove; compound eyes small, nearly round, strongly convex but in dorsal view weakly projecting from head silhouette, finely faceted. Punctures on vertex and frons distinct, small and shallow but sharply marked, unevenly distributed, separated by spaces 0.5–2 × as wide as diameters of punctures. Setae long, sparse, erect and mostly directed dorsoanterad; a pair of longer but similarly thin setae can be seen on posterior margin of vertex, close to posteromedian impression. Antennae ( Fig. 1 ) short and compact, AnL 1.85–1.95 mm (mean 1.89 mm), scape slightly shorter than head, antennomere II weakly elongate, III–VII each about as long as broad, VIII–X each slightly transverse, XI about as long as broad.

Labrum with indistinct anteromedian notch.

Pronotum subquadrangular, broadest near anterior margin; PL 0.95–0.98 mm (mean 0.96 mm), PW 1.08–1.13 mm (mean 1.11 mm); anterior and posterior corners obtuse-angled and blunt, but relatively well-defined; sides nearly straight and strongly convergent posterad; pronotal base with shallow and short diffuse median impression; posterolateral portions of pronotum protruding dorsoposterad ( Fig. 2 ) and overhanging posterior pronotal margin, interrupting transverse groove demarcating vestigial posterior collar, the latter reduced to short and narrow transverse area in posteromedian pronotal impression; lateral portions of transverse groove run along sides of pronotum, not visible in dorsal view. Punctures on disc similar to those on head; setae long, sparse and suberect. Cuticle between punctures on pronotal disc as glossy as that on head.

Elytra shield-shaped, broadest just behind humeri, EL 2.13–2.20 mm (mean 2.18 mm), EW 1.63–1.70 mm (mean 1.66 mm), EI 1.29–1.33; humeri well-defined, obtuse-angled; elytral apices unmodified, subtriangular; each elytron with five dorsal and one lateral rows of large and deep, densely and almost evenly distributed pits, cuticle between pits glossy, between rows with fine and sparse evenly distributed setiferous punctures; setae much longer and slightly thicker than those on head and pronotum, moderately dense, erect.

Hind wings absent.

Legs long and slender; protrochanter ( Fig. 2 ) modified, with robust anteroventral subtriangular projection.

Aedeagus ( Figs 18 –519) strongly elongate but moderately slender, in lateral view strongly curved, AeL 0.80 mm; parameres long, symmetrical, in ventral view each paramere with subtriangular apex slightly curved mesad; flagellum differentiated from ductus ejaculatorius by a rapid broadening of walls near base of median lobe and gradually narrowing distad. 'Sperm pump' ( Fig. 20 ) 0.52 mm in length, long and slender, with two shallow 'funnels', distal funnel narrower than proximal one.

Female. Externally very similar to male, on average indistinctly smaller and with broader elytra; protrochanters unmodified; antennae slightly shorter in relation to BL; BL 3.68–3.73 mm (mean 3.70 mm); HL 0.65 mm, HW 1.08–1.10 mm (mean 1.09 mm), AnL 1.73–1.75 mm (mean 1.74 mm); PL 0.95–0.98 mm (mean 0.96 mm), PW 1.08–1.13 mm (mean 1.10 mm); EL 2.05–2.13 mm, EW 1.60–1.68 mm (mean 1.65 mm), EI 1.24–1.28 mm.

Spermatheca ( Fig. 2 ) with oval capsular part with asymmetrical, subconical and long projection that surrounds insertion site of ductus spermathecae, width (diameter) of capsular part 0.50 mm; accessory gland inserted at base of subconical projection; ductus spermathecae relatively short and weakly entangled; bursa copulatrix short, tubular, forming a semi-coil.

Distribution. Western Sri Lanka.

Etymology. The name refers to the smallest body among all Sri Lankan Clidicus species, and the country name.

Remarks. Clidicus minilankanus can easily be distinguished from its sympatric congeners on the basis of the smallest body (the largest specimen examined is 3.83 mm long; C. mussardi and C. quadricollis exceed 4.8 mm, adults of C. loebli are nearly 6.5 mm long, and those of C. monstrosus exceed 7.7 mm). It is the only Sri Lankan species with well-defined, obtuse-angled humeri ( Fig. 1 ); all remaining species have the humeri broadly rounded ( Figs 3–6 ). Clidicus minilankanus is most similar to C. quadricollis , with which it shares a similar shape of the pronotum with the unique posteromedian impression ( Figs 7, 12 ), and a similar shape of the elytra ( Figs 1, 6 ). The male of C. quadricollis remains unknown, but females of C. minilankanus have the same shape of the humeri as males and consequently the shape of the elytra in these two species is clearly different.

Figures

FIGURES 1–6. Clidicus of Sri Lanka; dorsal habitus (1, 3–6) and protrochanter in lateral view (2). Clidicus minilankanus sp. n., holotype male (1) and paratype male (2; arrow showing modified protrochanter); C. loebli Besuchet, holotype female (3); C. monstrosus (Walker), lectotype female (4); C. mussardi Besuchet, holotype male (5); C. quadricollis Besuchet, holotype female (6).

FIGURES 7–12. Clidicus of Sri Lanka; head and pronotum in dorsal (7–10, 12) and posterodorsal (11) views. Clidicus mi- nilankanus sp. n., holotype male (7); C. loebli Besuchet, holotype female (8); C. monstrosus (Walker), lectotype female (9); C. mussardi Besuchet, holotype male (10–11; arrow showing transverse groove demarcating pronotal collar); C. quadricollis Besuchet, holotype female (12).

FIGURES 13–17. Clidicus of Sri Lanka; head and thorax in ventral view. Clidicus minilankanus sp. n., paratype female (13); C. loebli Besuchet, holotype female (14); C. monstrosus (Walker), lectotype female (15); C. mussardi Besuchet, holotype male (16); C. quadricollis Besuchet, holotype female (17).

FIGURES 18–21. Clidicus minilankanus sp. n. Aedeagus in ventral (18) and lateral (19) views; sperm pump (20); ovipositor with spermatheca (21).