Diochus antennatus ( Motschulsky, 1858 )

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 : 537-541

11. Diochus antennatus ( Motschulsky, 1858)

( Figs 1J ; 12-1; 12-2, 12-3)

Rhegmatocerus antennatus Motschulsky, 1858: 659 (Type locality: Indes orientales).

Diochus antennatus ; Gemminger and Harold, 1868: 608 (catalog); Bernhauer and Schubert, 1914:319 (catalog); Bernhauer, 1922: 231 (Formosa); Bernhauer, 1928: 15 (Sumatra); Cameron, 1932: 46 (characters; Penang; Malay Peninsula); Scheerpeltz, 1933: 1323 (catalog; Malay-Halbinsel, Formosa, Neu Guinea); Cameron, 1934: 79 (type examined); Cameron, 1937: 4 (Java); Shibata, 1973: 130 (Taiwan); Coiffait, 1982: 27 (characters; Nepal); Herman, 2001: 2444 (catalog); Smetana, 2004: 624 ( Taiwan; Nepal); Zhou and Zhou, 2016: 20 (characters).

Syn.: Diochus indicus Kraatz, 1859: 113 (Type locality: India orientalis); Bernhauer and Schubert, 1914: 319 (synonym of D. antennatus ); Cameron, 1931: 360 (New Guinea); Cameron, 1932: 46 (synonym of D. antennatus ); Smetana, 2004: 624 (synonym of D. antennatus ); Löbl & Löbl, 2015: 1007 (Palaearctic catalog; synonym of D. antennatus ).

Lectotype (by present designation) male: EAST INDIA: “65” (handwriting), “ Ostindien ” (printed), “ Coll. Kraatz ” (printed), “ Diochus indicus Krtz. “ (handwriting), “ Syntypus ” (red, printed) ( SDEI). Additional labels: “ LECTOTYPUS Diochus indicus Kraatz, J. Janák des. 2022” and “ Diochus antennatus (Motschulsky) , J. Janák det. 2022” were attached to the specimen . Paralectotypes: 2 females: “Ostindien” (printed), “Coll. Kraatz” (printed), “ Diochus indicus Krtz. “ (handwriting), “Syntypus” (red, printed), “PARALECTOTYPUS Diochus indicus Kraatz, J. Janák des. 2022” and “ Diochus antennatus (Motschulsky) , J. Janák det. 2022” (SDEI). Rhegmatocerus antennatus : In the 1990ʼs, one of us (JJ) examined one male syntype from Motschulskyʼs collection with the label: “Ind. or.” and drew a pencil illustration of the aedeagus, sternite IX and apical part of sternite VIII. The pictures were redrawn and published by Zhou & Zhou (2016: Fig. 8) .

Diochus indicus : One of us ( JJ) examined four syntypes from Kraatzʼs collection ( SDEI), three of them (1 male, 2 females) are conspecific and identical with D. antennatus . The male is here designated as lectotype to stabilise the identity of the species. The last syntype (male) with different locality labels (“ Indien ”, “ Schaum ”) belongs to a different species. All specimens were remounted, glued on new card plates together with the original small triangle plates, and aedeagi, spermatheca and last segments were embedded in Euparal on a plastic plates, placed on the same pins as the specimens.

Additional material examined. MYANMAR: 1 male: “ Birmanie, Helfer ”, “ Darjeeling , Sikkim ”, “indicus Kr. type”, “punctipennis Mots. , indicus Kr. ”, “Ex-Typis” ( IRSNB, coll Fauvel) . THAILAND: Chanthaburi: 8 males, 3 females, Khao Sabap Nat. Park , 150–300 m, 23–24. XI. 1985, Burckhardt-Löbl ( MHNG) ; NE Bangkok: 3 males, Khao Yai Nat. Park, Khao Khieo , 1150 m, 28. XI. 1985, Burckhardt-Löbl ( MHNG) ; 1 male, 2 females, Khlong Nakha Wildlife Sanctuary, Kapoe Dist. , 30 m, 29. 1. 1991, P. Schwendinger ( MHNG) ; 1 male, 4 specimens, sex indet., Chiang Mai, Doi Suthep National Park, Nov. 2019, Mok Fa waterfall , leaf litter, 08.11.2019, leg. Kleeberg ( AKBC, JJRC) ; 2 males, 1 female, Khao Lak N.P., Thone Chong Fa Fall , 100-300 m, 6.-15. I. 1998, leg. A. Schultz & K. Vock ( SMNS, JJRC) . MALAYSIA: 1 male, 1 female, Penang, Dr. Cameron ( NHML)

Measurements. BL = 3.75 mm, FL = 1.95 mm, HL = 0.51 mm, HW = 0.42 mm, EyL = 0.15 mm, TL = 0.28 mm, ANL = 1.08 mm, ANT1 = 0.15 mm, ANT2 = 0.09 mm, ANT3 = 0.09 mm, ANT4 = 0.06 mm, ANT 11 = 0.13 mm, PL = 0.69 mm, PW = 0.57 mm, EL = 0.70 mm, EW = 0.73 mm, SL = 0.50 mm.

Redescription. Body long, narrowed anteriorly and posteriorly, medium sized. Body dark brown, abdominal intersegmental membrane lighter. Legs brown, tarsi distinctly lighter. Antennae dark brown to yellowish brown, apex of each antennomere lighter. Maxillary and labial palpi brown.

Head (Figs 12-1A, E). Slightly 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 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 as long as half the length of tempora (eye: tempora = 0.55). Epistoma not flattened, abruptly oblique, anterior margin slightly emarginate medially. Distance between antennal insertions (0,16) distinctly longer than distance from antenna to eye (0.09). Ventral surface with scattered punctures, interspaces between them about 4 puncture diameters. Gular sutures deep, approaching to each other before basal 1/4, but not confluent, parallelly extended to base.

Antennae (Figs 12-1B, F). Scape rod-shaped, slightly thickened apically, distinctly shorter than two subsequent antennomeres combined; antennomere 2 slightly elongate; antennomere 3 about as long as 2; length of antennomere 4 about 1.5 times longer than width, antennomere 4 to 10 gradually shortened, antennomere 4 observably longer than 10; antennomere 11 distinctly longer than 10.

Mouthparts (Figs 12-1A, E). Labrum oval-shaped, lateral margin rounded, widest at basal 1/2; width of anterior margin is about 1/3 the width at the widest point. Mandibles falciform, left one with a sharp tooth and two blunt teeth on inner margin, right one with two teeth.

Neck (Figs 12-1A, E). Cylindrical, shiny, only bearing shallow microsculpture, width 0.13 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 (Figs 12-1A, E). Pronotum dark brown, elongate (PL to PW ratio 1.20), distinctly longer and wider than head. Anterior region near anterior angles deflexed, lateral margins widened posteriad to basal 1/3 (widest at 1/3), 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 12-1A, E). 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 12-1A, E). Elytra dark brown, slightly transverse (EL to EW ratio 0.96), 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 12-1G). First four segments of protarsi heart-shaped, strongly dilated, and those of meso- and metatarsi slender. Last segment of protarsi slightly longer than 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 12-1C–D, I–L; 12-2A–D; 12-3A–E). Head without elevation between eyes. Sternite VIII elongate, posterior margin emarginate medially (Figs 12-1C–D, I; 12-3B). Posterior margin of tergite VIII arcuate (Figs 12- 1J; 12-3C). Tergite IX (Figs 12-1L; 12-3D) symmetrical, connected mediobasally, narrowed apically. Sternite IX (Figs 12-1K, 12-3E) symmetrical, widest near the middle; basal margin deeply emarginate, apical margin slightly emarginate; width of apical margin distinctly shorter than basal margin. Tergite X (Figs 12-1L; 12-3D) symmetrical, triangular. Aedeagus (Figs 12-2A–D; 12-3A) symmetrical, small-sized, ca. 0.40 mm long, sclerotized. Parameres symmetrical, thin and long, slightly curved, cross at dorsal side, about 2/3 length of median lobe. Internal structures sclerotized, composed of two parts: T-shaped sclerite at top, brown color; paired rectangular sclerites and an asymmetrical sclerite in the middle, in brown to black color.

Female (Figs 12-2E–G). Head without elevation between eyes. Sternite VIII with posterior margin rounded. Tergite IX bearing numerous setae, elongate and sharply pointed apically. Sternite IX symmetrical, with deep concaved margin in middle. Tergite X broad, basal margin curved. Sternite X slender and rhomboidal, with numerous setae in lower half. Tube of spermatheca (Figs 12-2E–G) sclerotized, thin and long, with an apical circle.

Diagnosis. This species differs from other species of the region by markedly elongate and shallowly emarginated male sternite VIII, aedeagus with apical sclerite transverse and spermatheca with a loop apically.

Distribution. Myanmar, Thailand, Malaysia. Published records from other regions ( Indonesia (Sumatra, Java, Kalimantan [Borneo]), China (Taiwan), Nepal) have to be checked.

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).