Diochus chambrieri Huang, Janák & Zhou, 2024

Huang, Tian, Janák, Jiří & Zhou, Hong-Zhang, 2024, Taxonomy of the genus Diochus Erichson (Coleoptera: Staphylinidae, Staphylininae, Diochini) of Papua New Guinea, Vanuatu and Solomon Islands, Zootaxa 5519 (1), pp. 103-118 : 111-115

3. Diochus chambrieri Huang, Janák & Zhou , sp. nov.

( Fig 1B ; Figs 4-1; 4-2)

Type locality. Vanuatu: Tanna : Ipenkangien.

Type material. Holotype: male, VANUATU: Tanna : Ipenkangien, 24−27. V. 1979, A. de Chambrier collected ( MHNG). [Nlles HEBRIDES Ile de Tanna Ipenkangien White Sands] . Paratypes: VANUATU: 1 female, with same data as holotype ; SOLOMON ISLANDS: 1 male, 1 female “SOLOMON IS. Malaita, Dala, 16/2/1965 PJM Greenslade 16688.”, “SOLOMON IS P. Greenslade BM 1966-477 ” ( NHMUK, JJRC) ; 1 female: “18/3/65 SOLOMON IS., Russel Is. PJM Greenslade 17102.”, “SOLOMON IS P. Greenslade BM 1966-477 ” ( NHMUK) .

Measurements. BL = 4.82 mm, FL = 2.17 mm, HL = 0.59 mm, HW = 0.50 mm, EyL = 0.19 mm,TL = 0.34 mm, ANL = 1.30 mm, ANT1 = 0.16 mm, ANT2 = 0.12, ANT3 = 0.15 mm, ANT4 = 0.11 mm, ANT 11 = 0.13 mm, PL = 0.81 mm, PW = 0.65 mm, EL = 0.76 mm, EW = 0.93 mm, SL = 0.57 mm.

Description. Body ( Fig 1B ) 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 (Fig 4-1A). Round square in shape, 1.18 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 large-sized, distinctly protruding laterad, longitudinal diameter about 1/2 the length of tempora (eye: tempora = 0.55). Epistoma not flattened, abruptly oblique, anterior margin slightly emarginate medially. Distance between antennal insertions (0.11 mm) distinctly longer than distance from antenna to eye (0.07 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 4-1B). Scape rod-shaped, slightly thickened apically, distinctly shorter than two subsequent antennomeres combined; antennomere 2 slightly elongate; antennomere 3 slightly longer than 2; antennomere 4 about thrice of width, antennomere 4 to 10 gradually shortened, antennomere 4 observably longer than 10; antennomere 11 distinctly longer than 10.

Mouthparts (Fig 4-1A). Labrum nearly hexagonal, lateral margin straight, widest at basal 1/3 to 1/2; width of anterior margin is about 1/3 the width at the widest point. Mandibles (Figs 4-1D) falciform, left one with three small teeth on inner margin, whereas right one with two.

Neck (Fig 4-1A). Cylindrical, shiny, only bearing shallow microsculpture, width 0.11 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 4-1A). Pronotum dark brown, elongate (PL to PW ratio 1.25), 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 scattered near each margin (including anterior, lateral and posterior margins). Prosternum bearing an observable transverse ridge between basisternum and furcasternum, angularly backwards.

Pterothorax (Fig 4-1A). 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 limiting mesocoxal cavity slightly arcuate. Discrimen region on metaventrite normally elevated.

Elytra (Fig 4-1A). Elytra dark brown, short and transverse (EL to EW ratio 0.82), 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 in median, also with 4−5 rows of punctures on deflexed portion.

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

Abdomen ( Fig 1B ). 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 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 4-1E–J; 4-2A–E). Head with a small round elevation between eyes. Posterior margin of sternite VIII emarginated deeply and arcuately (Figs 4-1E, L; 4-2B). Posterior margin of tergite VIII arcuate (Figs 4-1F; -2C). Tergite IX (Figs 4-1H; 4-2D) symmetrical, connected mediobasally, narrowed apically. Sternite IX (Figs 4-1G; 4- 2E) asymmetrical, widest near basal 1/2; basal margin straight, apical margin normally emarginated; width of apical margin distinctly shorter than of basal margin. Tergite X (Figs 4-1H; 4-2D) symmetrical, triangular. Aedeagus (Figs 4-1I−K; 4-2A) symmetrical, medium-sized, ca. 0.61 mm long, normally sclerotized. Parameres symmetrical, thick and short, about 1/7 length of median lobe. Internal structures sclerotized, composed of four parts: paired trapezoidal sclerites on upper middle, brown color; paired strip shaped sclerites on both sides, black colored; paired rectangular sclerites and one irregular sclerite in the middle, brown color. Sperm pump coiled, thinned toward apex.

Female (Figs 4-2F−I). Head without elevation between eyes. Sternite VIII (Fig 4-2F) with posterior margin rounded. Tergite IX bearing numerous setae, elongate and sharply pointed apically. Sternite IX (Fig 4-2H) symmetrical, with deep concaved margin in middle. Tergite X broad, basal margin curved. Sternite X (Fig 4-2G) slender and rhomboidal, with numerous setae in lower half. Tube of spermatheca sclerotized, very long and strongly coiled (Fig 4-2I).

Distribution. Vanuatu.

Diagnosis. This species is similar to D. papuanus in body size and coloration, male sexual structures are also similar. The main difference is the length of elytra. In D. papuanus the elytra are distinctly shorter. In addition, for D. papuanus , male sternite VIII is provided with numerous setae on posterior emargination, while D. chambrieri sp. nov. is without setae, and the parameres of D. papuanus are distinctly longer and slender.

Etymology. The species epithet is dedicated to the collector of the holotype, Mr. A. de Chambrier ( Switzerland).

Figures

FIGURE 1. Habitus of four species from Papua New Guinea, Vanuatu and Solomon Islands in dorsal view:A. Diochus elongatus sp. nov.; B. D. chambrieri sp. nov.; C. D. papuanus Cameron, 1939, D. D. loebli sp. nov. (Scale bar: 0.5 mm).