Dasyhelea incisura sp. nov.

Type material.

Holotype ♂, India, West Bengal, Nadia, Krishnanagar [23°24'04.1"N, 88°28'48.9"E], 21.II.2017, Coll. S. Brahma.

Diagnosis.

The only species in the subgenus Dasyhelea Dasyhelea having an urn shaped clypeus with basal region having pointed shape; flat gonostylus tip bearing subapical notch or constriction at inner side and series of long setae at ventrolaterad of gonostylus.

Description.

Male (n = 1) (Figs 3A-K, 8A). Total body length 2.08 mm.

Head. Dark brown in colour. Eyes separated by half of diameter of ommatidium. Frontal sclerite (Fig. 3A) heart shaped basally with apical long projection, with broad base, 69 μm long, 55 μm wide, evenly sclerotised except apical projection less sclerotised. Flagellum (Fig. 3B) brown, 0.7 mm long; flagellomere XIII with a distinct apical nipple; flagellomeres III-XIII (only visible) with sensilla basiconica; length ratio of flagellomeres (I-XIII): 27: 14: 15: 15: 15: 15: 16: 16: 16: 32: 28: 25: 35; AR 0.88. Clypeus (Fig. 3C) urn shaped, with 4 pairs of setae. Palpus (Fig. 3D) pale brown; length ratio of palp segments (I-V): 7: 13: 16: 12: 11; PR 4.00; palp segment III with 4 capitate sensilla at apex.

Thorax (Fig. 3E). Chocolate brown in colour with two longitudinal pale stripes on both sides dorsally. Acrostichals 7-8 pairs, irregularly biserial; dorsocentrals 4-5 pairs, irregularly biserial and 5-7, uniserial; scutellum with 7 setae.

Wing (Fig. 3F). Wing with sparse macrotrichia. WL 1.1 mm, WW 0.36 mm, CR 0.48. Cubital fork starting before costal extremity.

Legs (Fig. 3G). Pale brown in colour. Hind femur infuscated at mid region. Hind tibial comb (Fig. 3H) with 7 spines. TRI 2.55, TRII 2.8 and TRIII 2.75.

Abdomen. Brown in colour.

Genitalia (Figs 3I, 8A). Tergite 9 broad, 154 μm long, 188.5 μm wide. Apicolateral processes (Fig. 3J) tubular, 23 μm long, with one prominent apical seta; cercus broad, 11.5 μm long, setose with one distinct seta at apex. Sternite 9 2.68 × wider than length, with convex posteromedian margin. Gonocoxite broad, stout, 85 μm long, greatest width 69 μm, having 4-5 setae dorsally and 20-23 setae ventrally. Gonostylus stout, 92 μm long, 18.5 μm wide basally, 13.5 μm wide apically with inwardly directed one prominent seta dorsally and ventrally each at about mid length; a distinct notch or constriction present on inner side at about three fourth length from base bearing two prominent setae, subapex bearing one seta ventrally and apex bearing two minute setae, mid ventrad of gonostylus with series of long setae. Left basal arm of parameres (Fig. 3I) 94.5 μm long, right one 57.5 μm long, both moderately sclerotised, recurved at anterior, right one strongly connected with 142.5 μm long, gradually tapered posteromedian projection of parameres, while left one having no attachment with parameres. Aedeagus (Fig. 3K) 48 μm long, 83 μm wide; basal arms 25 μm long, stout, highly sclerotised at tip, directed laterad enclosing 50.5 μm wide basal arch; posterolateral arms 39 μm long, inflated a little with apical recurved tip, directed laterad; ventromedian projection lacking.

Female adult. Unknown.

Pupa and Larva. Unknown.

Etymology.

The name " Dasyhelea incisura " derived from Latinised version of notch, referring to presence of prominent notch on inner side at three fourth length from the base of gonostylus in male genitalia.

Remarks.

Dasyhelea (Dasyhelea) incisura sp. nov. resembles D. digna Borkent, 1997 (USA) in similar posterior margin of sternite 9, very similar parameres and overall same appearance of aedeagus, but tip of the gonostylus and tip of the posterolateral arm of aedeagus are contrasting. Both parameres and aedeagus of D. correntina Ronderos, Díaz & Spinelli, 2004 (Argentina) are roughly alike with those of D. incisura, but the tip of the gonostylus, the tip of the posterolateral arm and the basal arm of the aedeagus are markedly different. The parameres of D. yunga Díaz, Spinelli & Ronderos, 2018 (Argentina) has close similarity with that of D. incisura, but the shape of the aedeagus is dissimilar. The combination of characters provided in the diagnosis validates D. (D.) incisura as a new member of this subgenus.

Distribution.

The specimen was collected from the Deltaic Proper of Gangetic West Bengal from an altitude of 14 meters - new species from India.

Ecological notes.

Adult Dasyhelea (D.) incisura sp. nov. were collected from shrub vegetation (Fig. 2A) when the air temperature was 25-26 °C and the relative humidity was 83%; no aquatic ecosystem was in proximity of the collection site.