Aphelocheirus (Aphelocheirus) thirumalaii, Basu, Srimoyee & Saha, Goutam K., 2013

Basu, Srimoyee & Saha, Goutam K., 2013, Overview of the species of Aphelocheirus (Hemiptera: Heteroptera: Aphelocheiridae) of India, with description of a new species from West Bengal, Zootaxa 3700 (2), pp. 293-299 : 293-296

Aphelocheirus (Aphelocheirus) thirumalaii sp. nov.

Type material. Holotype (brachypterous male in 70% alcohol, Zoological Survey of India, Kolkata, H.Q., Reg. No.: 2775/H15) from Dhupjhora, Murti River (Lat.: N 26.7818°, Long.: E 88.8411°, Alt.: 151.7 m a.s.l.), within the Gorumara National Park, Jalpaiguri district, West Bengal, India, 17.III.2012, collected by Srimoyee Basu.

Paratypes: 4 males, 11 females (all brachypterous, in 70% alcohol, Zoological Survey of India, Kolkata, H.Q., Reg.No.:2776/H15) with the same collection data as holotype.

Description of brachypterous male:

Size: Body length 7.0– 7.7 mm; ovate in appearance ( Fig. 1 ); maximum body width across 3rd abdominal segment 4.3–4.6 mm; width of pronotum 2.8 mm; maximum width of head (including eyes) 1.6 mm; width of head (excluding eyes) 1.2mm.

Colour: Dorsally, colour varies from pale brown to dark brown. Head yellow with an inverted ‘V’-shaped marking towards the anterior margin, a more or less triangular fuscous spot posteriorly; eyes black. Pronotum overall brown with a more or less rectangular yellow spot medially; lateral margin pale. Scutellum yellow. Hemelytra dark brown with light brown embolium. Abdominal tergites fuscous with pale brown lateral margins; Ventrally, head including antenna shining yellow; rostrum brownish, yellow basally. Abdominal ventrites dark brown; lateral margins pale yellow. Legs light yellow; claws yellowish with brown apical parts. Genital segment light yellow.

Head: Dorsally, with fine punctures, slightly produced ahead of eyes. Anterolateral corners of eyes with very, short, sparse setae. Head length 1.4 mm, twice as long as eye length; eyes 2.3 times longer than broad (L/W = 0.7/ 0.3); interocular space three times as wide the eye width. Antenna glabrous; length of antennal segments1_ 4: 0.12 mm, 0.16 mm, 0.22 mm, 0.31 mm, respectively. Rostrum 4-segmented, reaching slightly beyond mesocoxa; length 3.0 mm, 2.1 times as long as fore femur.

Thorax: Pronotum: length 0.73 mm, width 2.85 mm, with dense punctures, denticulate laterally; posterior margin nearly straight. Scutellum glabrous, almost triangular, 2.5 times broader than long, tip acuminated. Hemelytra touching each other at mid-line ( Fig. 4 ), each 1.5 times longer than broad, with intense punctures; embolium with sparse, black, short hairs. Propleura rounded posteriorly, with blunt inner propleural projection. Mesosternum moderately rugose medially, with a median carinae ( Fig. 3 ), just above mesocoxa. Metasternum weakly carinate; metaxipus small, laterally concave with apex more or less acuminate.

Abdomen: Abdominal tergites with dense black short hairs, laterally on each side. Tergites II–IV symmetrical; pair of abdominal scent glands located on posterior margin of tergum III at a distance of 0.84 mm. Lateral margins of sterna IV–VI sinuate, of sternum II straight; antero-medial margin of sternum IV–V with concavity, sternum VI asymmetrical; sternum II with a pair of well-developed prominent oval shaped pale yellowish hydrostatic sensory organs; all sterna with sparse short hairs laterally and stiff setae projecting from the lateral margin; spiracular rosettes on sterna II–VI located equidistantly from lateral margins, rosettes on sterna VI and VII reduced greatly; postero-medially, sternum IV–VI with median protrusion, but without peg-like setae.

Legs: Fore femora with prominent golden setae; bunch of long hairs at outer margin and small dense golden hairs at inner margin; mid and hind femora and tibia with dense long golden hairs; claws well-developed and curved; hind tibia marked with golden hairs at inner margin, outer margin with several golden spines. First tarsal segment very short compared to second and third. Measurements of leg segments as given in Table 1 .

Genitalia: Genital capsule broadly rounded ( Fig. 6 ), with scattered golden, prominent hairs. Parandria as in Fig. 5 ; left parandrium much longer and more acuminated towards apex than the right one; right parandrium wide with truncated apex. Aedeagus ( Fig. 5 ) elongated and slender, well-sclerotized, its apex slightly acuminated. Left paramere distinctly wider than the right one. Left paramere ( Fig. 10 ) stout, gently curved, widened sub-basally and at distal two thirds of length, slightly constricted near mid-length, tapering towards its narrowly rounded apex; seven spines arranged in two parallel rows. Right paramere ( Fig. 9 ) relatively slender, acuminated basally, with nearly uniform width and more concave apically; six stout spines located medially and bunch of setae arising from the concave margin.

Description of brachypterous female: Size: Body length 7.0 – 7.5 mm ( Fig. 2 ); maximum body width across 3rd abdominal segment 4.2–4.5 mm; width of pronotum 2.9–3.2 mm; width of head (including eyes) 1.5–1.6 mm; width of head (excluding eyes) 1.15–1.2 mm.

Colour: Colour pattern and setation, dorsally and ventrally, same as in male except abdominal sterna including genital segments these being comparatively darker in female; subgenital plate in female infuscated with pale luteous colour both distally and basally.

Head: Length of head 0.8 mm, twice as long as eye length; eye 1.3 times longer than broad (L/W=0.4/0.3). First antennal segment very short; length of antennal segments 1–4: 0.07 mm, 0.1 mm, 0.2 mm, 0.3 mm respectively. Length of rostrum 3.5 mm, reaching up to hind coxa and 2.7 times as long as fore femur. Pronotum 3.4 times as broad as long. Legs similar to those of brachypterous male. Measurements of leg segments are provided in Table 2.

LEG FEMUR TIBIA TARSOMERE2 TARSOMERE 3 Fore leg 1.35–1.37 1.14–1.20 0.19–0.24 0.19–0.23 Mid leg 1.48–1.52 1.36–1.41 0.20–0.24 0.29–0.34 Hind leg 1.89–1.92 2.35–2.41 1.17–1.21 0.63–0.68 Abdomen: Abdominal sterna symmetrical; lateral margins of sterna III–VII sinuate. Subgenital plate ( Fig. 8 ) narrowly triangular, with sub-apical and lateral setal tuft and extreme lateral long setal tuft on each side; a broad medial zone, clothed with golden setae.

Macropterous form: Unknown.

Diagnosis. Aphelocheirus (Aphelocheirus) thirumalaii sp. nov. is differentiated from all the known species of the nominotypical subgenus by its relatively small, slender, and dark brown appearance and the characters of the male's parameres and the female's subgenital plate.

Etymology. This species is named after the late Dr. G. Thirumalai, Scientist, Zoological Survey of India, and a renowned expert on aquatic Hemiptera of the Indian region.

Habitat. The type locality was within Gorumara National Park, Jalpaiguri district of West Bengal. The specimens were collected from a shallow, swiftly flowing stream, a continuation of the rain-fed Murti River, which is a tributary of the Teesta River. The substratum is rocky, full of loose gravels and pebbles covered with algae ( Fig. 11 ). Riparian vegetation is mainly deciduous forest with open canopy.

Figures

FIGURE 11. Type locality of Aphelocheirus thirumalaii sp. nov.

FIGURES 1 – 10. 1 – 4. Aphelocheirus thirumalaii sp. nov. (1) Dorsal view of male. (2) Dorsal view of female. (3) Ventral view of thorax illustrating inner propleural projection (IPP), Hydrostatic sensory organ (HSO) and metaxyphus. (4) Close dorsal view of head, thorax and hemielytra. 5 – 10. Aphelocheirus thirumalaii sp. nov. (5) Genitalia, dorsal aspect, after dissecting parameres: aedeagus with left and right paradrium; (6) Genital capsule of male; (7) Male genital segment; (8) Female subgenital plate; (9) Right paramere of male; (10) Left paramere of male.

Tables

TABLE 1. Measurements of different leg segments (values in mm.) of male (n = 5).

LEG	FEMUR	TIBIA	TARSOMERE2	TARSOMERE3
Foreleg	1.48–1.50	1.16–1.23	0.22–0.25	0.30–0.33
Mid leg	1.52–1.57	1.39–1.45	0.22–0.26	0.34–0.39
Hind leg	1.92–2.02	2.33–2.37	1.22–1.26	0.63–0.66