Metrocoris lavitra Basu, Polhemus, Subramanian and Saha

Basu, Srimoyee, Polhemus, D. A., Subramanian, K. A., Saha, G. K. & Venkatesan, T., 2016, Metrocoris Mayr (Insecta: Hemiptera: Gerridae) of India with descriptions of five new species, Zootaxa 4178 (2), pp. 257-277 : 261-262

Metrocoris lavitra Basu, Polhemus, Subramanian and Saha , NEW SPECIES

Figs. 17–32

Material examined. Holotype: Apterous male: INDIA, West Bengal, Jalpaiguri District , Chapramari Wildlife Sanctuary , stream infront of Chapramari railway gate, 26.8859°N, 88.8280°E, 176 m . asl., 10.III. 2011, coll. S. Basu, deposited in the Zoological Survey of India, H.Q., Kolkata ( NZSI) Reg. No. 4621/H15.

Paratypes: INDIA, West Bengal: 3 apterous males, 21 apterous females, Jalpaiguri District, Chilapata forest, Bania River , 26.6065°N, 88.4042°E, 74 m . asl., 19. IV. 2013, coll. S. Basu ( NZSI) Reg. No. 4622/H15; 5 apterous males, 7 apterous females, Jalpaiguri District, Chaitanyajhora, stream flowing through Rajabhatkhawa forest , Buxa Tiger Reserve range, 26.6174°N, 89.5305°E, 77 m . asl, 19. IV. 2013, coll. S. Basu (NZSI) Reg. No. 4778/H15.

Description. Apterous male (Holotype): Fig. 17

Size: Body length 6.30 mm, width across acetabula 3.16 mm.

Colour: Body colour varying from dark orange to yellowish, with scattered black markings. Interocular dark mark black, triangular, bluntly pointed posteriorly. Inner margin of eyes dark. First antennal segment yellow basally, remainder of antenna entirely black, with silvery dots. Dark markings on all nota ( Fig.19 ). Longitudinal dark stripe of mesopleuron much narrower than yellowish part, not connected to anterior margin or short acetabular stripe. Fore femur with two dark stripes and distal dark broad ring. Longitudinal broad dark stripe not connected to ring dorsally. Fore, mid and hind tibiae and tarsi black. Abdomen mostly orange with horizontal black stripes, terga I–VII orange with narrow black margins ( Fig. 23 ). Tergum VIII orange with two short longitudinal dark bands on each side. Venter bright yellowish orange.

Structural Characteristics: Head length 0.67, width 1.61. Posterior eye width 1.4 times width of eye. Eye length 0.8. Posterior half of eye covering almost half of propleuron. Interocular eye width 0.49. Length of antennal segments I–IV: 2.48, 0.89, 1.16, 0.86. Rostrum length 1.72, reaching fore trochanter. Pronotum 3.3 times as broad as long (width 1.52, length 0.45). Pronotum slightly bulbous. Meso- and metanota slightly broader than long (width 2.78, length 2.53). Fore femur slender, ratio of length/width 6.87, with slight curvature marked with small, prominent apical tooth and long hair fringe distally, two long setae basally, inner margin with a row of short hairs. Inner surface of tibia hairy, without indentation but with several small spines arranged equidistantly from base to apex ( Figs. 21, 22 ). For measurements of leg segments see Table1 .

Male genitalia: Male abdominal tergum VIII subquadrate, length 0.61, width 0.63, densely covered with black and golden short stiff hairs. Pygophore broader than long. Proctiger elongated, convex medially on both sides, with small, angular lateral lobes ( Fig. 28 ), clothed with dense hairs. Parameres ( Figs. 31, 32 ) symmetrical, projecting prominently from genital segment, sickle shaped, outer margin sinuate, apex expanded to form small head, tip rounded. Endosomal sclerites as in Fig. 29 .

Apterous female: Fig. 18

Size: Body length 5.49, width across acetabula 2.69.

Colour: Color pattern and marking patterns similar to male.

Structural Characteristics: Head length 0.62, width 1.53. Eye 1.7 times longer than broad (length 0.76 mm, width 0.43). Posterior eye width (0.51) 1.1 times as long as interocular width (0.45). First antennal segment longer than second, lengths of antennal segments I–IV: 1.96, 0.86, 1.19, 0.65. Pronotum 3.4 times as broad as long (width 1.61, length 0.47). Rostrum length 1.5. Length of combined meso- and metanota 2.42, width 2.05. Female fore femur similar to that of male, slender with small, triangular apical tooth but without curvature. Ratio of length/ width of fore femur 4.98. Inner surface of fore tibia with short fringe hairs, lacking spines. Middle leg longer than hind leg in both sexes. For measurements of leg segments see Table 2 .

Female terminalia: Abdominal tergum VII square ( Fig. 25 ), fringed with short hairs, with broad medial lobe, length 0.71, width 0.52. Female sternum V with medially invaginated apical margin, sterna II-IV with dense thick hairs medially and the density reduced laterally towards the margin. Sternum VII elongated, bilobed, laterally constricted basally, fringed with golden short hairs and with concave apical margin.

Macropterous forms. Unknown.

Etymology. The specific epithet comes from the Sanskrit word for sickle, “ lavitra ” and refers to the sickleshaped parameres of this species.

Habitat. Metrocoris lavitra was collected from a number of different freshwater ecosystems, including slowflowing streams, rivers, and forested pools. This species is common in the conservation areas of the Jalpaiguri District, such as the Chapramari Wildlife Sanctuary, the Chilapata forest, and the Buxa Tiger Reserve, all in West Bengal. This species prefers undisturbed, shady areas within the forest.

Comparative notes. This species does not fit well into to any currently defined Metrocoris species group. It can be distinguished by its elongate body of more than 6 mm in length; the triangular interocular mark; the slender male fore femur, which bears a small tooth; the elongate, subquadrate abdominal tergum VIII in the male; and the elongate female abdominal sternum VII.

Figures

FIGURES 17 – 32. Metrocoris lavitra sp. nov. 17. Dorsal view of apterous male; 18. Dorsal view of apterous female; 19. Head, pronotum, meso- and metaotum of apterous male; 20. Ventral view of apterous male; 21. Dorsal view of male fore leg; 22. Ventral view of male fore femora; 23. Abdominal tergum of male; 24. Abdominal sternum of male.