Diochus divisus Fauvel, 1877

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 : 360-363

5. Diochus divisus Fauvel, 1877

(Figs 6-1; 6-2)

Fauvel, 1877: 235 (Type locality: Australie, Nouvelle Galles du Sud); Olliff, 1887: 473 (characters; Australia); Bernhauer and Schubert, 1914: 319 (catalog); Lea, 1925: 220 (characters; Australia).

Type material examined. AUSTRALIA: Lectotype [designated here]: female, “Nlle Galles du Sud” (Fauvelʼs handwriting) // “divisus Fvl. ” (Fauvelʼs handwriting) // “Ex-Typis” (printed, red letters) // “R.I.Sc.N.B. 17.479 Coll. et det. A. Fauvel” (printed) ( IRSNB); Paralectotype: female, “Nlle Galles du Sud” (curatorʼs handwriting) // “Ex-Typis” (printed, red letters) //“R.I.Sc.N.B. 17.479 Diochus divisus Fauv. Coll. et det. A. Fauvel” (printed and with curatorʼs handwriting) ( IRSNB).

Note. We examined two female syntypes from the Fauvelʼs collection. Both specimens were remounted, glued on new card plates, spermathecae and last abdominal segments were embedded in Euparal on plastic plates placed on the same pin as the respective specimen together with an original small rectangular card plate. The first specimen labelled with Fauvelʼs handwriting was chosen as a lectotype to stabilize the taxonomic position of the species and the following label was added to the specimen: “ LECTOTYPUS Diochus divisus Fauvel, Huang, Zhou, Janák et Zhou des. 2024”. The second specimen labelled with curators handwriting was designated as a paralectotype and the following label was added to the specimen: “ PARALECTOTYPUS Diochus divisus Fauvel, Huang, Zhou, Janák et Zhou des. 2024”.

Measurements. BL = 3.73 mm, FL = 2.19 mm, HL = 0.58 mm, HW = 0.45 mm, EL = 0.16 mm, TL = 0.33 mm, PL = 0.76 mm, PW = 0.59 mm, EL = 0.79 mm, EW = 0.76 mm, SL = 0.53 mm.

Redescription. Body (Fig 6-1A, E) long, narrowed anteriorly and posteriorly, medium-sized. Body reddish brown, abdomen brown with intersegmental membrane and apical margins segments reddish, posterior half of elytra and abdominal segments VII and VIII light reddish yellow, mouthparts, legs and antennae light reddish yellow, tarsi yellow, antennomeres 3−7 very slightly infuscate. Maxillary and labial palpi light reddish yellow.

Head (Fig 6-1B). Moderately long and wide, 1.29 times as long as wide. Tempora slightly rounded and widened behind, posterior angles rounded. Dorsal surface shiny, bearing very fine hardly visible transverse microstriae and mesh, also with coarse and very 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, slightly protruding laterad, longitudinal diameter about half of length of tempora (eye: tempora = 0.47). Epistoma not flattened, abruptly oblique, anterior margin slightly emarginate medially. Ventral surface with scattered punctures, interspaces between them about 4 puncture diameters. Gular sutures deep, confluent at basal 1/4, then extended to base.

Antennae (Fig 6-1C). Scape rod-shaped, slightly thickened apically, shorter than two subsequent antennomeres combined; antennomere 2 elongate, 3 slightly longer than 2; 4 about 1.5 as long as wide, 5 to 10 gradually shortened, 4 about as long as 10; 11 distinctly longer than 10.

Mouthparts. Labrum oval-shaped, lateral margin rounded, widest at basal 1/2; width of anterior margin about half the width at widest point. Mandibles falciform, left one with three small teeth on inner margin, whereas right one with two.

Neck. Cylindrical, shiny, only bearing shallow microsculpture, shorter than 1/3 of head width. First half of dorsal surface depressed, with distinct groove. Ventral surface with gular sutures forming obvious triangular region, with deep transverse median furrow.

Prothorax (Fig 6-1B). Pronotum elongate (PL to PW ratio 1.29), 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 composing of 3 large punctures and 2 additional punctures outside of puncture row, several punctures scatted near each margin (including anterior, lateral and posterior margins). Prosternum bearing transverse ridge between basisternum and furcasternum, angularly backwards.

Pterothorax (Fig 6-1B). 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. The discrimen region on metaventrite normally elevated.

Elytra (Fig 6-1B). About as long as wide (EL to EW ratio LT: 1.04, PLT: 0.99), slightly longer and distinctly wider than pronotum. Humeri well developed, lateral margins divergent posteriorly, hind margin not rounded, but obliquely truncate. Dorsal surface shiny, flattened, without microsculpture, finely coriaceous; each elytron with irregular row of 7−9 punctures along suture, row of 7−9 punctures in median, also with 7−9 punctures on deflexed portion.

Legs (Fig 6-1E). First four segments of protarsi heart-shaped, hardly dilated, and those of meso- and metatarsi slender. Last segment of protarsi almost equal to 2−4 together, that of meso-, meta- slightly shorter than length of each 2−3.

Abdomen (Figs 6-1A, E). Broadest at segment V. Tergites III–VII covered with deep transverse microstriae and mesh; each tergite with dense pubescence, also with row of darker and coarser setae at posterior margin of tergites III–VI. Tergites III–VII with basal impression near anterior margin, respectively, each one only possessing one basal transverse carina. All abdominal tergites dull, with fine and very dense puncturation, distance between punctures mostly as large as diameter of puncture. Posterior margin of tergite VII with distinct palisade fringe. All abdominal sternites dull, with microstriae and punctures as those on tergites.

Male. Unknown.

Female. (Fig 6-2A–D). Head without elevation between eyes. Sternite VIII with posterior margin rounded. Tergite IX (Fig 6-2A) bearing numerous setae, elongate and rounded apically. Sternite IX (Fig 6-2B) symmetrical, with deep concaved margin in middle. Tergite X broad, basal margin curved. Sternite X (Fig 6-2B) slender and rhomboidal, with numerous setae in lower half. Tube of spermatheca sclerotized, very long and strongly coiled (Fig 6-2C–D).

Diagnosis. The female type specimens resemble D. pubiventris in body size, but it has distinctly light color on the apical half of elytra (Fig 6-1A, E). The spermatheca of this species is very long and coiled multiple times (Figs 6-2C−D), whereas the spermatheca of D. pubiventris is much shorter with fewer coils (Fig 9-3I).

Distribution. New South Wales.