Plagiostenopterina sagarensis Roy, Parui and Mitra, 2017

Roy, Sankarsan, Parui, Panchanan & Mitra, Bulganin, 2017, Plagiostenopterina sagarensis sp. nov. (Diptera: Platystomatidae: Platystomatinae) from Sunderban Biosphere Reserve, India with a key to Indian species, Zootaxa 4294 (4), pp. 487-493 : 488-492

Plagiostenopterina sagarensis Roy, Parui and Mitra sp. nov.

Type locality: India, West Bengal state, South 24 Parganas district, Sunderban Biosphere Reserve , Sagar Island , Sikarpur ( Latitude : 21°48.462ʹ N, Longitude : 088°10.038ʹ E).

Type materials (03 specimens): Holotype (male) labelled: India, West Bengal, Sunderban, Sagar Island, Sikarpur , 20.V.2015, coll. B. Mitra and Party . Paratype (female) labelled: India, West Bengal, Sunderban, Sagar Island, Sikarpur , 20.V.2015, coll. B. Mitra and Party . Paratype (male) labelled: India, West Bengal, Sunderban, Sagar Island, Sikarpur , 21.V.2016, coll. B. Mitra and Party. The type materials are deposited in the National Zoological Collection (NZC) of Zoological Survey of India , Kolkata.

Description. Holotype (male) ( Fig. 3)

Head. Frons slightly broader anteriorly and gradually narrowed, dark brown with two narrow greyish-yellow pollinose vittae on lateral margins, frons-eye ratio 1:1.5. Face uniformly yellowish brown, clypus-face ratio 1:5. Parafacial brownish yellow, narrower than first flagellomere. Gena brownish yellow, gena and eye ratio 1:3. Outer side of the antennae and apical region of inner side dark brown, rest of the inner side divided with brown on the upper half and yellow on the lower half; arista microscopic pubescent basally. Head chaetotax normal but ocellar and frontoorbitals absent. Occiput dark brown. Proboscis yellowish brown; palpus brownish yellow.

Thorax. Dark brown, lusturus with greyish pollinose stripe and spots. Mesonotum with a broad greyish stripe in the middle through the whole length; postnotal lobe greyish pollinose laterally with concolourous hairs. Notopleuron greyish pollinose. Anepisternum, anepimeron, katatergite, anatergite and subscutellum all grey pollinose. Scutellum concolourous with thorax bearing a pair of apical and subapical bristles. Thoracic chaetotaxy normal. Haltere yellowish white.

Wings hyaline, a brown costal band extending from the base of cell Sc to apex of vein M1+2 and distinctly wide at apex between R4+5 and M1+2. Cell bc and c yellowish tinged, cell br hyaline; R-m cross vein and Dm- cu cross vein infuscated. Wing span ± 5.46 mm ( Fig. 4).

Legs uniformly dark brown with apex of femora yellowish, fore femur with a row of long bristles on apical half postero-ventrally and with another row antero-ventrally through whole length ( Fig. 5), mid and hind femora with fine white hairs

Abdomen. Yellowish brown, base of 1st tergum with dark brown infuscation which gradually narrowed to posterior margin, 2nd tergum with a dark brown median stripe, in 3rd tergum the stripe after middle widens and reaches lateral margin, 4th tergum entirely dark brown except a yellowish spot laterally at anterior margin.

Male genitalia ( Fig. 6 & 7): Epandrium almost rectangular in shape with surstyle projecting downwards; cerci semi-circular at apex with yellowish piles. Phallus long looped, glans bulbous shaped attached to phallus; two terminal filament arises from distal end of glans; ejaculatory apodeme funnel shaped.

Variation (Paratype, female). Similar to male in general appearance, first flagellum almost uniformly dark brown; apex of all femora slightly yellowish; abdomen uniformly dark brown.

Remarks. Among the five reported species from India, P. teres is closely similar to the present species P. sagarensis sp. nov. in respect of wing colouration and superficial resemblance with shape of male genitalia. The comparisons with P. teres have been made on the basis of the description of Hendel (1914) and the illustrations of wing and male genitalia provided by Wang and Chen (2006). The present species P. sagarensis is distinctly differs from P. teres by the following sets of character: shape of costal band, infuscation on R-m and Dm- cu cross vein, thorax and abdomen colouration. Apical part of costal band of P. sagarensis distinctly wider than P. teres ; R-m and Dm- cu cross vein are infuscated in P. sagarensis , whereas not infuscated in P. teres . The colour of thorax and scutellum is dark brown in P. sagarensis while the thorax is reddish brown and scutellum red in P. teres . Abdominal colouration of P. sagarensis is yellowish brown but shining dark blue violet in P. teres .

Etymology. The name sagarensis refers to the name of the type-locality Sagar Island, Sunderban, West Bengal.

Distribution. So far reported from only type-locality, Sikarpur, Sagar Island of Sunderban, which is located in the district 24 parganas (South) of the state West Bengal, India.

Figures

FIGURE 6. Male genitalia of Plagiostenopterina sagarensis sp. nov. (Abbreviations: cerc, cercus; epand, epandrium; gls, glans; sur, surstylus; ph, phallus.)