Idris bianor Sushama, Rajmohana & Debnath sp. nov

Fig. 1

Diagnosis

Idris bianor Sushama, Rajmohana & Debnath sp. nov. can be distinguished from other Oriental species at once by the presence of black lateral patches on T1–T4. In the identification key for the species of Idris in India (Rajmohana 2014), this species keys to I. munnarensis Mukerjee, 1978, but can be separated from the latter by its smaller A3 (0.3× of A2 length vs 0.6× of A2 length), longitudinal parallel costae extending to ¾ of T2 medially (in I. munnarensis, costate only basally) and by the presence of black lateral patches on metasoma (in I. munnarensis, absent). In the species identification key of Lê (2000), this species runs to I. nautalis Kozlov & Lê, 1987; however, I. bianor can be distinguished from the latter by the shorter metasoma (1.3× as long as wide vs 2× as long as wide), presence of black lateral patches on T1–T4 (in I. nautalis, absent), and the absence of longitudinal striae on T3 (in I. nautalis, present). While much similar to I. javensis (Girault, 1917), I. bianor differs mainly by the presence of black lateral patches on T1–T4 and the presence of a central keel on frons.

Etymology

The specific epithet is after spider host of genus Bianor G.W. Peckham & E.G. Peckham, 1886 (Araneae: Salticidae) and is intended as a noun in apposition.

Type material

Holotype INDIA • ♀; West Bengal, East Burdwan, Kalna; 23.244° N, 87.897° E; 52 m alt.; 10 Oct. 2022; Rupam Debnath leg.; ex eggs of Bianor angulosus (Karsch, 1879); ZSI/34210/H3.

Paratypes INDIA – West Bengal • 5 ♀♀; South 24 Parganas, Raidighi; 21.9965° N, 88.4365° E; 26 m alt.; 21 Nov. 2021; V. Sushama leg.; ex eggs of Bianor angulosus (Karsch, 1879); ZSI/34211/H3 to ZSI/34215/H3 • 2 ♀♀; South 24 Parganas, Patharpratima; 21.7355° N, 88.4102° E; 20 m alt.; 26 Nov. 2022; V. Sushama leg.; ZSI/34216/H3, ZSI/34217/H3 • 2 ♀♀; South 24 Parganas, Kakdwip; 21.8866° N, 88.1705° E; 13 m alt.; 9 Nov. 2023; V. Sushama leg.; ex eggs of B. albobimaculatus (Lucas, 1846); ZSI/34218/ H3, ZSI/34219/H3 • 3 ♀♀; Murshidabad, Ekghoria; 23.9122° N, 87.96501° E; 42 m alt.; 24 Oct. 2022; Rupam Debnath leg.; ex eggs of B. angulosus (Karsch, 1879); ZSI/34220/H3 to ZSI/34222/H3 • 8 ♀♀; same data as for holotype; ZSI/34223/H3 to ZSI/34230/H3 • 3 ♂♂; same data as for holotype; ZSI/34231/H3 to ZSI/34233/H3.

Description

Female

BODY LENGTH. 0.65–0.92 mm (n = 20).

COLOUR. Head light brown; mesoscutum, mesoscutellum brown except reddish brown mesoscutellar lateral margins; metasoma, mandibles, legs and antennae pale yellow except brownish black patches laterally on T1–T3 and posterolaterally towards median of T4; propodeum black; wings hyaline; setae on body white.

HEAD. 1.7× as wide as high; 1.1× as high as long; 2.0× as wide as long; HW/TSL= 1.4; IOS 0.5× HW; head including frons, vertex, gena reticulate with scattered setae; central keel incomplete, reaching up to lower eye margin; lagrimal small, smooth; facial striae absent; malar striae absent; eyes sparsely pubescent; mandible tridentate, upper tooth longest; lateral ocelli contiguous with orbital margin; POL> LOL in ratio of 2:1; POL 9.0× OD; hyper occipital carina absent; occipital carina complete; A1 4.0× as long as wide; A1 and clava subequal to equal in length; A2 2.7× A 3 in length; A3 subequal in length and width; proportions of length to width of A1 to A6 (101:24), (48:24), (18:14), (10:15), (7:14), (5:22); clava 2.0× as long as wide.

MESOSOMA. Mesoscutum and mesoscutellum 0.7× and 0.5× as long as wide respectively and with same sculpture as on vertex; notauli absent; mesoscutal suprahumeral sulcus and mesoscutal humeral sulcus absent; scutoscutellar sulcus foveolate laterally in axillar area and smooth medially; posterior mesoscutellar sulcus foveolate; metascutellum smooth; metanotal trough foveolate; propodeum longitudinally striated submedially, placed apart by 3.0× of its own width; pronotal suprahumeral sulcus absent; epomial carina absent; cervical pronotal area with same sculpture as on vertex; lateral pronotal area smooth; mesopleural pit present; mesopleural carina incomplete, restricted to anterior half; prespecular sulcus foveolate; mesepimeral sulcus foveolate up to mesopleural pit and then present as a strong carina towards mesocoxa; femoral depression smooth; dorsal and ventral metapleural area smooth; metapleural pit distinct, from which metapleural sulcus extends as a smooth furrow anteriorly towards posterior margin of mesopleuron and posteriorly towards posterior margin of metapleuron; metapleural sulcus foveolate anterodorsally; paracoxal sulcus present as a simple furrow.

WINGS. Macropterous; forewing (L:W = 45:14), m: pm: st = 2:1:3; hindwing (L:W = 35:6).

METASOMA. 1.3× as long as wide. T1 with longitudinal parallel costae throughout; T2 longitudinally costate up to ¾ of its length medially and decreasing in length laterally, finely reticulate laterally, smooth apically; T3 longest and widest of all tergites, 2.1× as long as T2, with fine reticulation, sparsely setose laterally and sub laterally, smooth apically; T4 and T5 reticulate basally, smooth apically, sparsely setose; T6 and T7 not visible in dorsal view; proportions of width to length of T1 to T5 (102:42), (144:72), (241:156), (212:47), (134:18); S1 longitudinally costate; S2 longitudinally costate basally; S3–S6 uniformly reticulate and moderately setose.

Male

Body length = 0.79 mm (n = 3). Morphologically similar to females with the main exception of antenna. Antenna 11-merous, last two segments fused, length to width ratio of A1–A11 (10:3), (6:3), (2:2), (2:3), (2:3), (2:3), (2:3), (2:3), (2:3), (2:3), (7:3).

Biology

Reared from the eggs of Bianor angulosus and B. albobimaculatus (Salticidae: Araneae) (Rajmohana et al. 2025).

Distribution

West Bengal (India), Pakistan (based on BLAST search).

Variation

Difference in female body length (see the description above) and metasoma of some females comparatively short, 1.1× as long as wide.

Molecular characterization

The mt COI sequences of I. bianor (GenBank: OR621048, OR621049, OR699988–OR699993, PP417915, PP426041) show a minimum genetic distance of 11.4% to an unidentified species of Idris from Canada (GenBank: MG514562). The intraspecific genetic distance ranged from 0.0 to 0.3% (Supp. file 2). Interestingly, the BLAST search of I. bianor sequence retrieved 100% similarity to a sequence of an unpublished scelionid specimen from Pakistan (BOLD: GMPJA9337-21).