Prosopistoma someshwarensis Ramya Roopa, Selvakumar & Subramanian

Roopa, S. Ramya, Selvakumar, C., Subramanian, K. A. & Sivaramakrishnan, K. G., 2017, A new species of Prosopistoma Latreille, 1833 and redescription of P. indicum Peters, 1967 (Ephemeroptera: Prosopistomatidae) from the Western Ghats, India, Zootaxa 4242 (3), pp. 591-599 : 593-595

Prosopistoma someshwarensis Ramya Roopa, Selvakumar & Subramanian n. sp.

Figs. 2–12

Material examined. Holotype: mature larva, INDIA, Karnataka, Someshwara Wildlife Sanctuary, Seethanadi river , Dulli Hole , 13°28’49.82’’ N, 075°02’43.77’’ E, 91 m, 04.III.2016, Coll. S. Ramya Roopa [ZSISRC-I/E 19] . Paratypes: 2 mature larvae, same data as holotype [ZSISRC-I/E 20]; 15 mature larvae, INDIA, Karnataka, Someshwara Wildlife Sanctuary, Seethanadi river, Yele Hole , 13°32’18.48’’ N, 075°04’43.14’’ E, 676 m, 06.VI.2015, 28.XII.2015, 17.III.2016, Coll. S. Ramya Roopa; 3 mature larvae , INDIA, Karnataka, Someshwara Wildlife Sanctuary, Seethanadi river, Onakeabbi falls , 13°30’46.41’’ N, 075°04’31.04’’ E, 597 m, 01.VI.2015, Coll. S. Ramya Roopa; 3 mature larvae , INDIA, Karnataka, Someshwara Wildlife Sanctuary, Seethanadi river, Onakeabbi falls , 13°30’27.07’’ N, 075°05’17.06’’ E, 655 m, 25.XI.2015, Coll. S. Ramya Roopa.

Description. Mature larva. Body length 4–4.5 mm excluding caudal filaments. Head uniformly reddish brown with median ocellus between antennae, width approximately 2.5 times length. Epicranial sutures clearly visible, passing through lateral ocelli and anterior margin of compound eyes, continuing to lateral margin of head ( Fig. 2 A). Carapace general coloration reddish brown, with one pale-coloured circular depression on each side of midline of anterior region of carapace, present at approximately 0.26 times length of carapace from posterior margin of head ( Fig. 2 B) and with many dark ridges including few ridges resembling longitudinal lines on surface ( Fig. 2 C).

Head. Antenna ( Fig. 4 ) 7-segmented including scape and pedicel, longer than distance from antennal base to anterior margin of head; segment III longest and shorter than combined length of segments IV–VII. Labrum ( Fig. 6 ) prominent when larva viewed dorsally, narrow, approximately 3.7 times wider than long, anterior margin fringed with dense fine setae. Left and right mandibles similar. Outer canine of mandibles longer and broader than inner canine, with three apical teeth, outer tooth small, inner tooth larger with margin serrated near apex with 4–5 small spines; inner canine with two apical teeth, inner one slightly larger, inner margin serrated near apex with 3–5 spines. 8–10 long serrated bristles arising from base of inner canine. Single stout, feathered seta present lateromedially on each mandible ( Fig. 5 ). Maxillae ( Fig. 7 ) crowned by rigid canine and three subequal moveable dentisetae; three long feathered, stout bristles arising near base of apical canine and dentisetae on galea-lacinia. Single unserrated bristle arising about two-thirds of way down sclerotized section of galea-lacinia. Length ratio of maxillary palp segments from basal one to apical one: 1.9:3.2:1. Labial palpi 3-segmented, length ratio of labial palp segments from basal one to apical one: 2:1.65:1 ( Fig. 8 ).

Legs. Dorsal margin of fore femur with 20 or 21 simple, short, feathery setae; ventral margin of fore tibia with 14 or 15 pectinate setae ( Fig. 9 ). Tarsal claws of all three pairs of legs without denticles.

Abdomen. Abdominal gills I–VI. Gill I large and branched ( Fig. 10 ). Gill II broad, leaf-like and unbranched ( Fig. 11 ). Gills III–V with multiple branching filaments ( Fig. 12 ). Gill VI tiny, unbranched. Posterolateral projections of abdominal segments VII–IX broad, apex pointed ( Figs. 2 & 3 ). Three retractile, short and feathery caudal filaments present.

Sub-imago and Imago. Unknown.

Distribution. India (Central Western Ghats).

Etymology. This species is named after the place of collection, Someshwara Wildlife Sanctuary, Karnataka, India.

Diagnosis. Prosopistoma someshwarensis n. sp. is most similar to P. alaini Bojková & Soldán 2015 , a recently described species from Algeria ( Bojková & Soldán 2015). However, P. someshwarensis n. sp. can be distinguished from all other species of Prosopistoma , including P. alaini , by the following combination of characters: (i) antenna 7-segmented including scape and pedicel; segment III the longest and shorter than combined length of segments IV–VII ( Fig. 4 ); (ii) epicranial sutures clearly visible, passing through anterior margin of lateral ocelli and between compound eyes and antennal bases or through lateral ocelli and anterior margin of compound eyes, continuing to lateral margin of head ( Fig. 2 A); (iii) carapace general coloration reddish brown, with one pale-coloured circular depression on each side of midline of anterior region of carapace ( Fig. 2 B) and with few longitudinal line that looks like a ridge on its surface ( Fig. 2 C); (iv) 8–10 long serrated bristles arising from the base of inner canine ( Fig. 5 ); (v) ventral margin of fore-tibia with 14–15 pectinate setae ( Fig. 9 ) and (vi) postero-lateral projections on abdominal segments VII–IX broad and apex pointed ( Figs. 2 & 3 ).

Ecology. The new species was collected from riffle habitat, underneath cobbles and gravel, in tributaries of the Seethanadi River, a west-flowing river in the central Western Ghats. The sampling sites were all located within tropical wet evergreen forests. The streams (Dulli Hole, Yele Hole and Onakeabbi falls) had average widths ranging from 0.92 m to 9.86 m and average depths ranging from 0.90 cm to 12.24 cm through the three seasons of sampling. The pH ranged from 6.26 to 8.48 and water temperature ranged from 20.8°C to 28.8°C.

Figures

FIGURES 2 – 8. Larva of Prosopistoma someshwarensis n. sp. 2. Dorsal view: 2 (A). Epicranial sutures, 2 (B). Circular depression, 2 (C). Ridges; 3. Ventral view; 4. Antenna; 5. Mandible; 6. Labrum; 7. Maxilla; 8. Labium.

FIGURES 9 – 12. Larva of Prosopistoma someshwarensis n. sp. 9. Foretibia; 10. Gill I; 11. Gill II; 12. Gill III.