Hyphydrus biswasi Ghosh 2021, sp. nov.

Hyphydrus biswasi Ghosh, sp. nov.

(Figures 1-7)

LSID: urn:lsid:zoobank.org:pub: 52AD4815-13B4-475A-9D80-7435867AB539

Type material (14 specimens). Holotype, male: India: Arunachal Pradesh, Namdapha National Park, Vijay Nagar, 21.xii.1984, Collected S. Biswas (NZSI). Paratypes: 8 males, 5 females, locality data same as holotype (NZSI).

Type locality. India: Arunachal Pradesh, Namdapha National Park, Vijay Nagar.

Type depository. The type specimens are deposited in the national zoological collections of the Zoological Survey of India, Kolkata (NZSI). The specimens of the newly described species are provided with one red printed label, “ Hyphydrus biswasi sp. nov., HOLOTYPE or PARATYPE ” Det. Sujit Kumar Ghosh.

Description (Holotype, male). Length 3.9 mm, width 2.5 mm.

Colouration (Figure 1). Body colouring testaceous to ferruginous with brownish-black colour pattern. Head testaceous with two slightly darkened spots at vertex near posterior margin to eyes; Antennae and palpi testaceous. Pronotum dark brownish-black; lateral sides with a slightly paler band. Elytra shiny black ferruginous with slightly irregular testaceous markings anteriorly and posteriorly; two testaceous spots present posteromedially. Legs testaceous; meta-legs dark ferruginous; 3 rd pro- and mesotarsomere and 3 rd to 5 th metatarsomere partly darkened, and blackish ferruginous. Ventral surface dark ferruginous, except testaceous head and prosternum.

Head (Figure 1). Anterior margin of clypeus slightly straight medially, somewhat rounded at sides, with a partially raised border. Punctation near clypeal margin fine and sparse, medially at vertex dense and fine. Clypeus micro-sculptured anteriorly. Clypeus with two large, and relatively shallow frontolateral depressions. 3 rd and 11 th antennomeres longer, 4 th antennomere smaller.

Pronotum (Figure 1). Punctation on surface of 2 types: coarse, and fine; coarse punctation sparse at base to middle and dense at middle to apex; fine punctation evenly distributed throughout. Sides of pronotum slightly curved and bordered. Angle between pronotum and elytra fairly distinct.

Elytra (Figure 1). Punctation on surface of 2 types: coarse and fine; coarser punctation sparsely distributed, whereas finer punctation more evenly distributed; punctation finer at lateral sides. Elytron with a discal row of punctures near elytral suture, disappearing after middle of elytron posteriorly; a row of irregular and an indistinct small line of punctures near lateral margins. Epipleura testaceous, with relatively fine punctation.

Venter. Punctation on metasternum fairly coarser; abdomen finely punctate. Apical sternite hooked.

Legs. Protrochanters incised with a fairly long, backwardly curved process; a furrow present at base of hooked process (Figure 2).

Aedeagus. Median lobe of aedeagus in ventral view parallel, narrowing at apex (Figure 3); penis incision relatively deep (Figure 3); apex of penis truncates with several short setae anterolaterally, lateral lobe of penis straight (Figure 5); base of penis with a strongly curved hooked process (Figure 5); right paramere with inner margin curved (Figure 6).

Variations. Length 3.4-4.2 mm, width 2.3-2.9 mm. Females same as holotype except in following characters: pro-trochanters lacking curved process; apical sternite not hooked; spermatheca as in Figure 7.

Etymology. The species is named after Late Dr Shyamrup Biswas, Retired Scientist at Zoological Survey of India, Kolkata, who devoted his career studying a different group of beetles from India.

Distribution: So far known from the type locality only.

Differential diagnosis: Hyphydrus biswasi Ghosh, sp. nov. belongs to Hyphydrus signatus species group. H. signatus species group comprises H. birmanicus Régimbart, H. gschwendtneri Guignot, H. intermixtus (Walker), H. renardi Severin, H. sumatrae Régimbart and defined by the set of following characters: 1) border of anterior margin of the head without a furrow, 2) elytral punctation two types (coarse and fine), 3) male pro-trochanters incised, 4) longer spine of metatibiae not serrate, 5) metatibiae externally with a distinct row of punctures, and 6) lateral lobes of penis not curved outwardly (Biström, 1982).

The newly described species is closely related to H. sumatrae (India: Assam, Manipur; China, Indonesia) but differs from it by the following characters: punctation near clypeal margin fine and sparse, vertex fine and dense (punctation coarse evenly distributed in H. sumatrae), the base of the penis with a sharply curved hooked process (hooked process straight, not curved in H. sumatrae), incision of penis relatively deep (narrow in H. sumatrae), apex of penis dorsally truncate (slight rounded in H. sumatrae), lateral lobe of penis straight (slightly elevated near apices in H. sumatrae), and right paramere with inner margin curved (straight in H. sumatrae). Also refer to key for differentiating the species in signatus species group from India.