Choroterpes (Choroterpes) andamanensis Vasanth, Subramanian & Selvakumar 2021, n. sp

Choroterpes (Choroterpes) andamanensis Vasanth, Subramanian & Selvakumar n. sp. (Figs 1–16) Material examined: Holotype: male larva, INDIA, Andaman and Nicobar Islands, Botanical Garden, Nayachaar; N 11.5738°, E 92.6741°; Alt. 54m.; 16.xi.2018, coll. K. A. Subramanian (Reg. No. I /E/438). Paratypes: 3 larvae (Reg. No. I /E/439), same data as holotype. Mature larva. Length: body, 4.3–5.0 mm; antennae, 2.8–3.0 mm; cerci, 5.2–5.5 mm; paracercus, 5.8–6.0 mm. General coloration yellowish brown (Figs 1–2). Head. Dark brown, washed with yellow. Upper portion of male compound eye reddish black. Antennae whitish yellow (Fig. 1). Labrum (Fig. 3): dark brown; anteromedian emargination shallow, broad with five blunt denticles. Hypopharynx (Fig. 4): lingua with well developed lateral process, with cleft anterior margin. Mandibles (Figs 5–6): translucent, dark brown and pale brown medially; lateral margins with scattered setae, inner incisor slightly longer than outer one. Second segment of maxillary palp subequal in length of segment I, segment III approximately ¾ length of segment II (Fig. 7). Labium (Fig. 8): glossae with plate-like thick setae on ventral surface and dense row of fewer setae on dorsal surface; paraglossae with denser but thinner setae on dorsal surface; first segment of labial palp with thick setae on lateral margins, second segment with hair-like setae on lateral margin, apical segment with thick and fine setae and small tufts; length of segment I subequal to segment II, segment III approximately ¾ length of segment II. Thorax. Yellowish brown, irregularly washed with dark brown; pronotum dark yellowish brown with diffuse black markings medially. Meso- and metathorax yellowish brown tinged with dark brown or black laterally. Legs (Figs 9–11): yellowish brown; each femur with a brown macula on middle and distal region; forefemur with thick setae on the dorsal surface, mid and hind femora with several well developed thick setae on dorsal surface; each femur with thick and thin setae on outer margin; fore and mid tibiae with fine and thick setae on inner margin, and very sparse and thin setae on inner and outer margin; hind tibiae with thick and few feathered setae on surface; tarsi of all legs with several thin setae on inner margin and sparse setae on outer margins. Claws apically hooked with a row of 8–9 denticles (Fig. 12). Abdomen. Terga I–X pale yellowish brown with diffuse black markings and spines on posterior margins; posterolateral margins of abdominal terga I– III with blunt denticles and IV–IX with pointed denticles, size of denticles progressively larger posteriorly. Sterna I–VII white and VIII–IX yellowish (Figs 1–2). Gills I–VII, well-tracheated, slender, gills II –VII with dorsal lamella larger than ventral (Figs 13–16). Sternum IX of male with deep apical cleft, sternum IX of female with apex entire and without emargination (Fig. 2). Caudal filaments pale yellow-brown; with a whorl of setae on alternate segments; setae shorter than length of corresponding segment. Adult. Unknown Etymology. The species named after the type locality, Andaman Islands. Distribution. Andaman Island (India). Diagnosis. Choroterpes (Choroterpes) andamanensis n. sp. can be distinguished from all known species of subgenus Choroterpes by the following characters: (i) anteromedian emargination of labrum broad with five blunt denticles (Fig. 3); (ii) gills II–VII with dorsal lamella larger than ventral (Figs 14–16). (iii) femur with brown macula on middle and distal region (Figs 9–11); and (iv) claw with a row of 8–9 denticles (Fig. 12). Habitat: Larvae of Choroterpes (Choroterpes) andamanensis n. sp. inhabit small (from 1.5–2 m wide) stream (Nayachaar) (Fig. 57) (up to 54 m a.s.l.) of the Port Blair district, Andaman Island. This stream is characterized by medium water temperature (25°С at the time of sampling), average current velocity and bottom substrate predominantly with pebbles, sand, leaf litter and silt particles. The new species was found with Baetis sp. Discussion. Presently, three species are recorded from the subgenus Choroterpes s. str. in India viz., Choroterpes (C.) petersi Tong and Dudgeon, 2003 from southern Western Ghats by Selvakumar et al., (2015) which was originally described from Hong Kong, Choroterpes (C.) kaegies Selvakumar, Subramanian & Chandra, 2017 described from Himachal Pradesh and Meghalaya and the present new species, Choroterpes (Choroterpes) andamanensis Vasanth, Subramanian & Selvakumar n. sp. from the Andaman and Nicobar Islands. The distribution of Choroterpes (C.) petersi Tong and Dudgeon, 2003 appears to be disjunct in its geographical range. Choroterpes (C.) kaegies Selvakumar, Subramanian & Chandra, 2017 is widely distributed in North and North-East India. Choroterpes (C.) andamanensis n. sp. is only known from Andaman Islands. However, extensive field surveys are required to explore the distribution of this subgenus in the Indian subcontinent.