Diochus keralanus Huang, Janák & Zhou, 2024

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 : 519-523

5. Diochus keralanus Huang, Janák & Zhou , sp. nov.

( Figs 1I ; 6-1; 6-2; 6-3)

Type locality. India: Kerala, Cardamon Hills , 10 km SW Kumily.

Type material. Holotype: male, INDIA: S-Indien: Kerala, Cardamom Hills, 10km SW Kumily, 77° 07ʼ E 09° 31ʼ N Vallakadavu , 1000 m, 24.12.1993, leg. Boukal & Kejval ( NHMW) . Paratypes: 2 males, INDIA: same data as holotype ( NHMW, JJRC) ; 1 male, Kerala, 1.1.1999, 30 km NNE Trivandrum, 300 m, Kallar Bridge , 08°45'N 77°05'E, leg. D. Boukal (37) ( NHMW) ; 1 female, Kerala: Cardamom Hills, 30 km W Kumily, Peermade , 900 m, 76° 59ʼ E 09° 34ʼ ( NHMW) ; 1 female, Cardamom Hills, 15 km SW Munnar, 76° 58ʼ E 10° 02ʼ N, Kallar valley , 6.- 18.12.1993, 1000 m (7) leg. Boukal & Kejval ( NHMW) ; 1 male, Kerala: Nelliampathi Hills N. O. Amaimalai Hills, 900 m, 30. XI. 1972, Burckhardt Löbl Mussard ( MHNG) ; 1 male, Kerala: Nelliampathi Hills , 300 m, 30. XI. 1972, Burckhardt Löbl Mussard ( MHNG) . Holotype with an identification label: “ HOLOTYPUS Diochus keralanus sp. nov. Huang, Janák & Zhou det. 2024” . Paratypes with identification labels: “ PARATYPUS Diochus keralanus sp. nov. Huang, Janák & Zhou det. 2024” .

Measurements. BL = 4.77 mm, FL = 2.49 mm, HL = 0.63 mm, HW = 0.47 mm, EyL = 0.18 mm, TL = 0.36 mm, ANL = 1.37 mm, ANT1 = 0.17 mm, ANT2 = 0.14 mm, ANT3 = 0.15 mm, ANT4 = 0.12 mm, ANT 11 = 0.14 mm, PL = 0.83 mm, PW = 0.64 mm, EL = 0.83 mm, EW = 0.81 mm, SL = 0.59 mm.

Description. Body long, narrowed anteriorly and posteriorly, large-sized. Body dark reddish brown, abdominal intersegmental membrane lighter. Legs yellowish brown, tarsi distinctly lighter. Antennae yellowish brown, apex of each antennomere lighter. Maxillary and labial palpi yellow.

Head (Figs 6-1A, D). Oblong in shape, 1.35 times as long as wide. Tempora straight and nearly parallel, 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 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 large-sized, distinctly protruding laterad, longitudinal diameter slightly longer than half the length of tempora (eye: tempora = 0.51). 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 (0.10 mm). Ventral surface with scattered punctures, interspaces between them about 4 puncture diameters. Gular sutures deep, confluent near the base.

Antennae (Figs 6-1B, E). Scape rod-shaped, slightly thickened apically, distinctly shorter than two subsequent antennomeres combined; antennomere 2 slightly elongate, antennomere 3 distinctly longer than 2; length of antennomere 4 about twice of width, antennomere 4 to 10 gradually shortened, antennomere 4 observably longer than 10; antennomere 11 distinctly longer than 10.

Mouthparts (Figs 6-1A, D). Labrum nearly hexagonal, lateral margin rounded, widest at basal 1/3 to 1/2; width of anterior margin is about 1/3 the width at the widest point. Mandibles (Fig 6-1G) falciform, left one with three small teeth on inner margin, whereas right one with two.

Neck (Figs 6-1A, D). Cylindrical, shiny, only bearing shallow microsculpture, width 0.16 mm, about 1/3 the head width. Dorsal surface with distinct groove; ventral surface with gular sutures forming obvious triangular region, with deep transverse median furrow.

Prothorax (Figs 6-1A, D). Pronotum elongate (PL to PW ratio 1.29), distinctly longer and wider than head. Anterior region near anterior angles slightly 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 composed of 3 large punctures and 2 additional punctures outside of puncture row, 13–15 punctures scattered near each margin (including anterior, lateral and posterior margins). Prosternum bearing an observable transverse ridge between basisternum and furcasternum, angularly backwards.

Pterothorax (Figs 6-1A, D). Mesoscutellum triangular, surface shiny, bearing distinct microstriae, but without any punctures. Transverse ridge on mesoventrite wave shaped; the paired oblique furrows short but deep; the carina delimiting mesocoxal cavity slightly arcuate. Discrimen region on metaventrite normally elevated.

Elytra (Figs 6-1A, D). Elytra yellowish brown, not transverse (EL to EW ratio 1.03), distinctly longer and 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 5 punctures on disc, also with 4−5 rows of punctures on deflexed portion.

Legs (Fig 6-1F). First four segments of protarsi heart-shaped, moderately dilated, and those of meso- and metatarsi slender. Last segment of protarsi nearly equal to 2−4 together, that of meso-, meta- nearly equal to the length of each 2−3.

Abdomen. Broadest at segment V. 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; all abdominal tergites with surface shiny, bearing polygonal microsculpture, 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 6-1C; H–K; 6-2A−D; 6-3A–E). Head without elevation between eyes. Posterior margin of sternite VIII emarginate medially (Figs 6-1C, H; 6-3B). Posterior margin of tergite VIII arcuate (Figs 6-1I; 6-3C). Tergite IX (Figs 6-1K; 6-3D) symmetrical, connected mediobasally, narrowed apically. Sternite IX (Figs 6-1J; 6-3E) symmetrical, widest near basal 1/3; basal margin slightly emarginate, apical margin slightly emarginate; width of apical margin about half of basal margin. Tergite X (Figs 6-1K; 6-3D) symmetrical, triangular. Aedeagus (Figs 6- 2A−D; 6-3A) symmetrical, medium-sized, ca. 0.64 mm long, normally sclerotized. Parameres symmetrical, thin and long, reaching about apical twentieth of median lobe. Internal structures sclerotized, paired horn-like sclerites on top in brown color, two paired helical sclerites in the middle in brown color. Sperm pump coiled, thinned toward apex.

Female. (Figs 6-2E−H). Head without elevation between eyes. Sternite VIII with posterior margin rounded. Tergite IX bearing numerous setae, elongate and rounded sharply pointed apically (Fig 6-2H). Sternite IX (Fig 6- 2G) symmetrical, with deep concaved margin in middle. Tergite X broad, basal margin curved (Fig 6-2H). Sternite X (Fig 6-2G) slender and rhomboidal, with numerous setae in lower half. Tube of spermatheca sclerotized, thin and long, curved with widened basal part (Figs 6-2E, F).

Distribution. India (Kerala).

Diagnosis. Head, pronotum and elytra of the new species are more elongated, with lighter coloration, the aedeagus possesses two long horn-like sclerites in apical part and several series of small spines in basal and median part. These characters easily distinguish the new species from other species.

Etymology. The name refers to the type locality.

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).