Stenus rugosellus Janák, 2022

Janák, Jiří, 2022, Four new species and additional records of the genus Stenus of southern Africa (Coleoptera: Staphylinidae: Steninae), Zootaxa 5174 (4), pp. 331-356 : 339-341

Stenus rugosellus Janák , sp. nov.

( Figs. 25–31 )

Type locality. South Africa, KwaZulu-Natal Province, Kokstad, surroundings of Stoneybrook farm .

Type material. Holotype ♂: SOUTH AFRICA: KwaZulu-Natal: “ South Africa, KwaZulu-Natal, Stoneybrook farm env. nr. Kokstad ; dam; 30°31.0´S, 29°19.9’E, 19.xi.2021, J.Janák lgt.”, “dam banks, reeds, treading”, “ HOLOTYPE Stenus rugosellus sp. nov., J. Janák det. 2022” ( TMSA) ; Paratype ♀: same data as holotype ( JJRC) . Paratype with additional label “ PARATYPUS Stenus rugosellus sp. nov., J. Janák det. 2022” .

Description (n = 2). Body length 4.2–4.3 mm (HT 4.2 mm, PT 4.3 mm), fore parts 2.1–2.3 mm (HT 2.1 mm, PT 2.3 mm). Macropterous, black, shiny, fore parts coarsely and very densely punctate, pronotum and elytra rugose, many punctures confluent, abdomen moderately coarsely and moderately densely punctate; pubescence distinct, recumbent ( Fig. 25 ). Antennae dark brown or blackish. Maxillary palpi yellowish, segments 3 and 4 slightly (HT) or markedly darkened (PT). Legs dark brown or black, basal third of femora reddish (HT) or dark brown (PT), tarsi dark brown. Clypeus black, labrum dark brown, moderately densely pubescent.

Head moderately narrower than elytra (R HT 77.9/96.5 = 0.81, PT 0.75), frons broad (average distance between eyes 38), with two distinct longitudinal furrows, median part as broad as each of the lateral parts, moderately elevated, not extending to the level of inner eye margins; punctation moderately coarse and dense, diameters of punctures as large as basal diameter of second antennal segment or slightly large, but not reached maximal diameter of this segment; antennal tubercles and median part impunctate, surface with faint reticulation. Antennae moderately long, when reflexed extending approximately to posterior fifth (HT) or fourth (PT) of pronotum, penultimate segments one-half longer than broad.

Pronotum strongly convex, slightly longer than broad (R HT 66.2/63.2 = 1.05, PT 1.07), broadest near middle, distinctly constricted behind; no distinct impression present; punctation coarse, very dense and rugose, many punctures confluent and forming short or longer mostly transverse rows, diameter of average punctures as large as maximal diameter of second antennal segment.

Elytra rounded trapezoid, slightly broader than head, slightly longer than broad (R HT 96.5/77.9 = 1.24, PT 1.34), shoulders slightly oblique, sides slightly rounded and markedly widened behind, distinctly constricted in posterior one-fifth, posterior margin moderately emarginate (sutural length 80–83); sutural, humeral and lateral impressions distinct; punctation slightly coarser than on pronotum, very dense and rugose, many punctures confluent, many punctures confluent and forming short or longer diagonal or transverse rows, diameter of punctures slightly larger than maximal diameter of second antennal segment, interstices mostly markedly smaller than diameter of punctures.

Abdomen broad (slightly narrower and more convex in HT than in PT), tergite 7 with distinct membranous fringe apically; punctation on basal tergites 3–5 moderately coarse and (except for middle) dense, interstices slightly to markedly smaller than diameter of punctures, on remainder of abdomen finer and sparser; punctures on tergite 4 markedly larger as one medial eye facet, punctures on tergite 7 markedly finer. Legs moderately slender, metatarsi two thirds as long as metatibiae, segment 1 slightly shorter than segments 2 and 3 combined, about as long as last, segment not bilobed. Pronotum and elytra finely reticulate (visible at magnification of 70 x), abdomen densely and shallowly reticulate.

Male. Sternite 7 medio-posteriorly flattened, finely and sparsely punctured, sternite 8 medially flattened, shallowly and broadly emarginated ( Fig. 26 ). Sternite 9 deeply emarginated ( Fig. 28 ). Tergite 10 broadly rounded ( Fig. 29 ). Aedeagus 0.72 mm long, pointed, narrowed apically, sides in middle slightly emarginate ( Fig. 27 ), parameres exceeds markedly median lobe, slightly widened apically, with numerous (about 20–22) setae.

Female. Sternite 8 broadly rounded apically, without any projection.Tergite 10 broadly and shallowly emarginate ( Fig. 31 ). Valvifer acute posteriorly ( Fig. 30 ).

Variability. The differences between the male holotype and the female paratype mentioned in the description I consider as a variability in the range of the species, which is supported mainly with in the capensis group exceptional rugose pronotum and elytra with many punctures confluent and forming short or longer rows.

Differential diagnosis. This new species belongs to the capensis group (species with unbilobed tarsomere 4, abdomen with paratergites, flatter, with median keels broad and short). It can be distinguished from the species of the group by rugose punctation of pronotum and elytra. The general shape and the aedeagus shape of the new species is similar as in S. hessei ( Figs. 32–33 ), but the new species differs above already mentioned rugose punctation also by more parallel and apically less narrowed median lobe with broader expulsion bands and shorter much less inside curved apicolateral teeth of male sternite 8.

Derivatio nominis. The name is derived from rugosus, referring to rugose punctation of pronotum and elytra.

Distribution. S. rugosellus sp. nov. is currently known only from surroundings of Stoneybrook farm near Kokstad in KwaZulu-Natal Province, South Africa.

Bionomics. The type specimens were found by treading of reeds on banks of a dam together with below described S. volkerputhzianus Janák , sp. nov. and S. callens Puthz.

Figures

FIGURES 25–37. 25–31: Stenus rugosellus Janák, sp. nov., 25–30, holotype; 29–30, paratype. 32–37: Stenus hessei L. Benick, 32, Heuningnes river, 33–37, Bordjiersrif. 25, habitus; 26, abdomen ventral; 27, 32, 33, aedeagus, dorsal; 28, 34, sternite 9; 29, 35, male tergite 10; 31, 37, female tergite 10; 30, 36, valves. Scale 1 mm: 25–26; scale 0.5 mm: 27–37.