Stenus praedator, Mainda, 2020

Mainda, Tobias, 2020, Stenus praedator sp. nov. from the Philippines and a new species group in Stenus Latreille, 1797 (Coleoptera: Staphylinidae, Steninae), Zootaxa 4759 (3), pp. 405-412 : 406-410

Stenus praedator sp. nov.

Figs 6 , 7 , 13, 18, 19

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Type material examined. Holotype ♂: “ Philippines: Mindanao Isl. , Barangay Baganihan , Marilog District , Eagles Ridge , 7°45’N, 125°23’E, 26.– 28.3.2018, secondary broad-leaved forest, sifted from wet litter near small rocks, leg. A. Shavrin ” [ZMM]. 1 Paratype ♀: “ Philippines: Mindanao, Mount Hamiguitan Range Wildlife Sanctuary, 6°43’48.0”N 126°08’24.0”E, 500 m, 30.III.–2.IV.2018, sifted from wet litter and debris near stream, leg. A. Shavrin ” [cM].

Description. Measurements of the HT (in mm): BL: 7.5, DE: 0.55, FBL: 3.6, EL: 1.23, EW: 1.15, HW: 1.25, PL: 1.27, PW: 0.9, SL: 0.8. Measurements of the PT (in mm): BL: 7.4, DE: 0.4, FBL: 3.5, EL: 1.22, EW: 1.17, HW: 1.25, PL: 1.27, PW: 0.9, SL: 0.8.

Habitus as in Fig. 6 . Micropterous, body black, shining, with weak metallic hue, completely without microsculpture; maxillary palpi, legs and antennae yellowish; labrum reddish-yellow.

Median portion of head shiny, about twice as wide as lateral portions and with tiny puncture in its anterior centre. Anterior inner eye-margin with three to five punctures; median portion separated from lateral portions by a series of punctures, diameter of punctures about as wide as basal cross-section of antennomere III. Clypeus and labrum with dense silvery pubescence. Antennae long and slender, extending to posterior margin of pronotum when reflexed; antennomere X about twice as long as antennomere XI.

Pronotum (Fig. 18) 1.4 times as long as broad, broadest in the middle, sides towards anterior margin slightly convex, towards posterior margin concavely narrowed. Punctation coarse and fairly dense, except for few little elevated impunctate areas on each side, largest punctures in dorsal middle as large as maximal diameter of antennomere III in cross-section, lateral punctation somewhat less coarse, interstices much narrower than diameter of punctures. Legs slender, metatarsi less than half as long as metatibia; metatarsomere I as long as the combined length of metatarsomeres II–V and longer than metatarsomere V; metatarsomere IV deeply bilobed.

Elytra 0.92 times narrow as head, 1.4 times as long as broad, humeral angles oblique, sides distinctly divergent posteriorly, suture unmodified. Punctation very coarse, diameter of punctures larger than apical cross-section of antennomere III, interstices mostly narrower than diameter of punctures.

FIGURES 13–18. Pronotum of S. heterocerus (13), S. thaumatocerus (14), S. quatei (15), S. inflaticollis (16), S. ernstjuengeri (17) and S. praedator sp. nov. (18).

Abdomen cylindrical; with short pubescence; basal impressions of tergites I–III very deep; punctation of basal impressions of tergites III and IV coarse; interstices much wider than diameter of punctures, their size about as large as an ommatidium at medial eye-margin up to the middle cross-section of antennomere V; punctation of tergites V–VII finer and sparser, interstices as wide as on tergite IV; punctation of tergite VIII denser than that of tergites III–VII, interstices wider than diameter of punctures.

Male. Femora slightly dilated. Metaventrite coarsely and densely punctured. Sternites III–VI unmodified, sternite VII ventrally flattened and medially more densely punctured than laterally, near posterior margin shallowly impressed; sternite VIII with a rounded notch in posterior sixth; sternite IX serrate apicolaterally; tergite X with convex posterior margin ( Fig. 19 ). Apical portion of aedeagus ( Fig. 7 ) acutely narrowed, expulsion-clasp with two “horns” (lower arrow); internal sac with long flagellum (upper arrow); parameres slightly extending beyond apex of median lobe, with six setae apically.

Female. Legs unmodified. Median pubescence of sternite VII denser than in lateral portions; sternite VIII broadly rounded at posterior margin; valvifer serrate apicolaterally.

Differential diagnosis. The species is distinguished from the similar S. ernstjuengeri by its male sexual characters, the structure of the pronotum, and the sparser punctation of the abdomen. It is separated from S. heterocerus by its denser and coarser punctation and from S. thaumatocerus by the male sexual characters and coarser punctation of the pronotum and elytra. It differs from S. inflaticollis by the punctation of the whole body and the male sexual characters and from S. quatei by denser punctation of the frons and the pronotum, as well as by the male sexual characters.

Etymology. The specific epithet refers to the fact that species of Stenus are predators.

Figures

FIGURE 19. sternite VIII, tergite VIII, sternite IX and tergite X (left to right) of Stenus praedator sp. nov.

FIGURES 4–6. Holotypes of S. inflaticollis (photo: Field Museum of Natural History 2019) (4), S. ernstjuengeri (photo: Museum of Comparative Science 2019) (5) and S. praedator sp. nov. (6).

FIGURES 7–9. Aedeagi of S. praedator sp. nov. (7), S. ernstjuengeri (8) and S. inflaticollis, holotype, from Puthz (1998) (9).