Diochus slipinskii, Huang & Zhou & Janák & Zhou, 2024

Huang, Tian, Zhou, Yu-Lingzi, Janák, Jiří & Zhou, Hong-Zhang, 2024, Four new species and a key to Australian species of the genus Diochus Erichson (Coleoptera: Staphylinidae, Staphylininae, Diochini), Zootaxa 5512 (3), pp. 343-372 : 356-360

4. Diochus slipinskii sp. nov.

(Figs 5-1; 5-2)

Type locality. AUSTRALIA: Western Australia: “Marun”, CALM Site 8/4 Prince Frederick Harbour .

Type material. Holotype: male, AUSTRALIA: Western Australia: (15.00S 125.21E) “Marun”, CALM Site 8/4 Prince Frederick Harbour, 6−11. VI. 1988, I.D. Naumann ( ANIC) . Paratypes: AUSTRALIA: Western Australia: 1 male, 3 females, with same data as holotype .

Measurements. BL = 4.07 mm, FL = 1.95 mm, HL = 0.52 mm, HW = 0.43 mm, EL = 0.14 mm, TL = 0.29 mm, ANL = 1.04 mm, ANT1 = 0.14 mm, ANT2 = 0.09 mm, ANT3 = 0.11 mm, ANT4 = 0.08 mm, ANT 11 = 0.11 mm, PL = 0.73 mm, PW = 0.60 mm, EL = 0.72 mm, EW = 0.89 mm, SL = 0.56 mm.

Description. Body (Fig 5-1A) long, narrowed anteriorly and posteriorly, medium-sized. Body entirely dark brown, abdominal intersegmental membrane lighter. Legs yellowish brown, tarsi distinctly lighter. Antennomeres brown, apex of each antennomere lighter. Maxillary and labial palpi brown.

Head (Fig 5-1A). Oblong in shape, 1.21 times as long as wide. Tempora slightly widened backwards, posterior angles rounded. Dorsal surface shiny, bearing distinct and transverse microstriae, also with coarse and sparse punctures. Head with 5−7 irregular, punctures scattered around each eye, and with numerous smaller punctures on deflexed portion of tempus and near posterior margin. Each side of cranium with characteristic punctures: one frontal puncture on frontal region, two anterolateral punctures near antennal insertion, three lateral punctures near dorsal margin of eye, with temporal puncture and occipital puncture near basal margin; disc surface bearing two additional paired punctures in middle area. Frontal furrows and anteocular furrows absent. Eye medium-sized, distinctly protruding laterad, longitudinal diameter about half of length of tempora (eye: tempora = 0.49). Epistoma not flattened, abruptly oblique, anterior margin slightly emarginate medially. Distance between antennal insertions (0.12 mm) distinctly longer than distance from antenna to eye (0.06 mm). Ventral surface with scattered punctures, interspaces between them about 4 puncture diameters. Gular sutures deep, confluent at basal 1/5, then extended to base.

Antennae (Fig 5-1B). Scape rod-shaped, slightly thickened apically, shorter than two subsequent antennomeres combined; antennomere 2 not elongate, 3 slightly longer than 2; 4 about 1.5 times of the width, 4 to 10 gradually shortened, 4 observably longer than 10; 11 distinctly longer than 10.

Mouthparts. Labrum nearly hexagonal, anterior margin almost straight, lateral margin straight, with widest at basal half; width of apical margin about half of width at widest point. Mandibles (Fig 5-1D) falciform, left one with three small teeth on inner margin, whereas right one with two.

Neck. Cylindrical, shiny, only bearing shallow microsculpture, width 0.14 mm, shorter than 1/3 of head width. Dorsal surface with distinct groove; ventral surface with gular sutures forming obvious triangular region, with deep transverse median furrow.

Prothorax (Fig 5-1A). Pronotum elongate (PL to PW ratio 1.22), distinctly longer and wider than head.Anterior region near anterior angles deflexed, lateral margins widened posteriad to basal 1/4 (widest at 1/4), then convergent backwards, anterior and posterior angles broadly rounded. Dorsal surface glossy, extensively with micropunctures, but without any microsculpture. Each side of longitudinal midline with one row of punctures composing of 3 large punctures and 2 additional punctures outside of puncture row, 13–15 punctures scatted near each margin (including anterior, lateral and posterior margins). Prosternum bearing transverse ridge between basisternum and furcasternum, angularly backwards.

Pterothorax (Fig 5-1A). Mesoscutellum triangular and small, surface shiny, bearing distinct microstriae, but without any punctures. Transverse ridge on mesoventrite wave shaped; paired oblique furrows short but deep; carina limiting mesocoxal cavity slightly arcuate. Discrimen region on metaventrite normally elevated.

Elytra (Fig 5-1A). Transverse and short (EL to EW ratio 0.81), distinctly longer and wider than pronotum. Humeri well developed, lateral margins divergent posteriorly, hind margin not rounded, but obliquely truncate. Dorsal surface shiny, flattened, without microsculpture; each elytron with row of 5 punctures along suture, row of 5 punctures in median, also with 4−5 rows of punctures on deflexed portion.

Legs (Fig 5-1C). First four segments of protarsi heart-shaped, moderately dilated, and those of meso- and metatarsi slender. Last segment of protarsi slightly longer than 2−4 together, that of meso-, meta- shorter than length of each 2−3.

Abdomen (Fig 5-1A). Broadest at segment V. Tergites III–VII covered with dense and transverse microstriae; each tergite with dense yellow pubescence, also with row of darker and coarser setae at posterior margin of III– VI. Tergites III–VII with basal impression near anterior margin, respectively, each one only possessing one basal transverse carina. All abdominal tergites with surface shiny, bearing polygonal reticulum, with dense punctures. Posterior margin of tergite VII with distinct palisade fringe. All abdominal sternites shiny, with microstriae and punctures as those on tergites.

Male (Figs 5-1E–J; 5-2A–E). Head with small round elevation between eyes. Posterior margin of sternite VIII emarginate medially, each side with shallow emargination (Figs 5-1E; 5-2B). Posterior margin of tergite VIII arcuate (Figs 5-1F; 5-2C). Tergite IX (Figs 5-1G; 5-2D) symmetrical, connected mediobasally, narrowed apically. Sternite IX (Figs 5-1H; 5-2E) asymmetrical, widest near basal 1/2; basal margin straight, apical margin normally emarginated; width of apical margin about twice of width of basal margin. Tergite X (Figs 5-1G; 5-2D) symmetrical, triangular. Aedeagus (Figs 5-1I–J; 5-2A) symmetrical, small-sized, ca. 0.46 mm long, normally sclerotized. Parameres symmetrical, thick and short, about 1/4 length of median lobe. Internal structures sclerotized, composed of six parts: paired connected J-shaped sclerites at top, black color; two paired strips shaped sclerites located on both sides, lateral one in black color and other in brown color; 5 sclerites in middle: paired rectangular sclerites in brown color, paired round sclerites in black color, one tongue-shaped sclerite in yellow color. Sperm pump coiled, thinned toward apex.

Female (Figs 5-2F–I). Head without elevation between eyes. Sternite VIII (Fig 5-2F) with posterior margin rounded. Tergite IX bearing numerous setae, elongate and sharply pointed apically. Sternite IX (Fig 5-2H) symmetrical, with deep concaved margin in middle. Tergite X broad, basal margin curved. Sternite X (Fig 5-2G) slender and rhomboidal, with numerous setae in lower half. Tube of spermatheca sclerotized, very long and strongly coiled (Fig 5-2I).

Distribution. Western Australia.

Diagnosis. The species is small-sized, similar to D. pubiventris and D. divisus . The male can be distinguished from D. pubiventris by darker antennae and the shape of sternite VIII. The darker elytra of D. slipinskii sp. nov. easily distinguish it from D. divisus .

Etymology. The species is dedicated to Dr. Adam Ślipiński ( Australia) in recognition of his outstanding contributions to the study of Coleoptera .