Diochus bicoloripennis Coiffait, 1981

Huang, Tian, Janák, Jiří & Zhou, Hong-Zhang, 2024, Six new species and a key to 12 species of the genus Diochus Erichson (Coleoptera: Staphylinidae, Staphylininae, Diochini) from India, Nepal and Pakistan, Zootaxa 5538 (6), pp. 501-545 : 541-543

12. Diochus bicoloripennis Coiffait, 1981

( Figs 1K ; 13 )

Diochus bicoloripennis Coiffait, 1981: 333 (Type locality: South Andaman , Jolly Boy Island).

Type material examined. INDIA: Andaman Islands : Holotype: female, “Type” (printed red), “S. Andaman, Jolly Boy Isl., 29-XII-1978, Osella” (handwrited) // “ Diochus bicoloripennis H. COIFFAIT det. 1980” (printed and Coiffaitʼs handwriting) ( MCVR) ( Fig 13E ).

Note. We examined the unique female holotype. The specimen was remounted, glued on a new card plate, and the spermatheca and last abdominal segments were embedded in Euparal on a plastic plate placed on the same pin as the specimen.

Measurements. BL = 4.08 mm, FL = 1.79 mm, HL = 0.50 mm, HW = 0.40 mm, EyL = 0.13 mm, TL = 0.28 mm, ANL = 0.96 mm, ANT1 = 0.19 mm, ANT2 = 0.08 mm, ANT3 = 0.09 mm, ANT4 = 0.05 mm, ANT 11 = 0.13 mm, PL = 0.66 mm, PW = 0.50 mm, EL = 0.66 mm, EW = 0.66 mm, SL = 0.46 mm.

Description. Body long, narrowed anteriorly and posteriorly, small-sized. Head dark reddish brown, pronotum and abdomen light reddish brown, elytra dark reddish brown, each elytron with light orange spot in posterior part, reaching from middle of lateral part to apical fifth of suture. Legs, antennae, maxillary and labial palpi light reddish yellow.

Head ( Fig 13B ). Relatively short, rounded trapezoid in shape, 1.26 times as long as wide. Tempora slightly rounded, slightly widened posteriad, posterior angles rounded. Dorsal surface moderately shiny, bearing distinct and short transverse mesh, also with coarse and sparse punctures. Head with 5−7 irregular, punctures scattered around each eye and 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, slightly protruding laterad, longitudinal diameter shorter than half the length of tempora (eye: tempora = 0.46). Epistoma not flattened, abruptly oblique, anterior margin slightly emarginate medially. Distance between antennal insertions (0.14 mm) distinctly longer than distance from antenna to eye (0.06 mm).

Antennae ( Fig 13C ). Scape rod-shaped, markedly thickened apically, slightly shorter than two subsequent antennomeres combined; antennomere 2 slightly elongate, antennomere 3 slightly longer than 2; antennomere 4 about as long as wide, antennomere 4 to 10 gradually shortened, antennomere 10 transverse, about 1.4 as wide as long; antennomere 11 distinctly longer than 10.

Mouthparts ( Fig 13B ). Labrum nearly hexagonal, lateral margin straight, widest at basal 1/3 to 1/2; width of anterior margin is about 3/4 the width at the widest point.

Neck ( Fig 13B ). Cylindrical, shiny, without microsculpture, width 0.14 mm, shorter than 1/3 of head width. Dorsal surface with distinct groove.

Prothorax ( Fig 13B ). Pronotum distinctly elongate (PL to PW ratio 1.33), markedly longer and moderately wider than head.Anterior region near anterior angles deflexed, lateral margins almost parallel, only slightly widened posteriad to basal 1/4 (widest at 1/4), then slightly convergent backwards, anterior and posterior angles broadly rounded. Dorsal surface glossy, with scattered very fine micropunctures, but without any microsculpture. Each side of longitudinal midline with one row of punctures composed of 3 large punctures and 2 additional punctures outside of puncture row, 10–12 punctures scattered near each margin (including anterior, lateral and posterior margins).

Pterothorax ( Fig 13B ). Mesoscutellum triangular, surface shiny, without distinct microsculpture and punctures.

Elytra ( Fig 13B ). Elytra trapezoid, as long as wide (EL to EW ratio 1.00), as long as but wider than pronotum. Humeri well developed, lateral margins divergent posteriorly, posterior margin not rounded, but obliquely truncate. Dorsal surface shiny, flattened, without microsculpture; each elytron with row of 5 punctures along suture, row of 6 punctures in median, also with 5–6 punctures in row on deflexed portion.

Legs ( Fig 13A ). First four segments of protarsi heart-shaped, moderately dilated, and those of meso- and metatarsi slender. Last segment of protarsi distinctly shorter than 2−4 together, that of meso-, meta- slightly longer than length of each 2−3.

Abdomen ( Fig 13A ). Broadest at segment IV. Tergites III–VII covered with dense and obvious transverse microstriae; each tergite with dense brown pubescence, also with row of darker and coarser setae at posterior margin of III–VI. Tergites III–VII with a basal impression near anterior margin, respectively, each one only possessing one basal transverse carina. Posterior margin of tergite VII with distinct palisade fringe.

Male. Unknown.

Female ( Fig 13D ). Head without elevation between eyes. Sternite VIII with posterior margin rounded. Spermatheca with two tubes, basal tube sclerotized, with many short bends along its length, ending in sclerotized plate, proximal tube less sclerotized but wider, with two bends.

Diagnosis. This species can be easily separated from all others by the bicolored elytra, which are dark basally and reddish yellow apically. The shape of the spermatheca is also unique. D. antennatus has similar body size, also has short antennae like this species, but has shorter pronotum. D. keralanus sp. nov. also has similar body size and long pronotum, but antennae longer. Both D. antennatus and D. keralanus sp. nov. have unicolored elytra.

Distribution. Andaman Islands (Jolly Boy Island).

Figures

FIGURE 1. Habitus of Diochus species from Bhutan, India, Nepal, Myanmar, Pakistan and Thailand in dorsal view: A. D. guizhouensis Shuai, Nozaki & Tang, 2021; B. D. setatus sp. nov.; C. D. setifer sp. nov.; D. D. emarginatus sp. nov.; E. D. cameroni sp. nov.; F. D. ceylonicus sp. nov., 1929; G. D. conicollis (Motschulsky, 1858); H. D. punctipennis (Motschulsky, 1858); I. D. keralanus sp. nov.; J. D. antennatus (Motschulsky, 1858); K. D. bicoloripennis Coiffait, 1981; L. D. ochraceus Cameron, 1926 (Scale bar: 0.5 mm; photos of six new species based on the holotype respectively).

FIGURE 13. Diochus bicoloripennis Coiffait, 1981: A. habitus, dorsal view; B. forebody, dorsal view; C. antenna; D. spermatheca; E. labels. (Scale bars: A, B = 0.5 mm, C–D = 0.1 mm).