Megaglena agasthiya Vasanth, Subramanian & Selvakumar, 2021

Vasanth, M., Subramanian, K. A., Selvakumar, C., Kubendran, T. & Sivaramakrishnan, K. G., 2021, Three new species of Atalophlebiinae (Ephemeroptera: Leptophlebiidae) of India with a new record of the genus Megaglena Peters and Edmunds, 1970, Zootaxa 5076 (1), pp. 56-70 : 64-68

Megaglena agasthiya Vasanth, Subramanian & Selvakumar n. sp.

( Figs 38–56 )

Material examined: Holotype: male larva, INDIA, Kerala, Trivandrum district, Peppara Wildlife Sanctuary, Pandipath stream, 8.67741° N, 77.19390° E; Alt. 1326 m; 19.i.2019, coll. M. Vasanth (Reg. No. I /E/436) . Paratypes: 5 larvae, same data as holotype (Reg. No. I /E/437) .

Mature larva. Length: body 12.5–13.5 mm; antennae 2.6–3.0 mm; cerci 6.5–7.0 mm; paracercus 7.2–7.5 mm. General coloration yellowish brown ( Figs 38–39 ).

Head. Brown, washed with yellow. Upper portion of eyes conspicuously large and red ( Fig. 38 ). Antennae pale yellow. Labrum ( Figs 41–42 ): deep ‘U’ shaped cleft on anteromedian emargination with blunt crenation on either side; dorsum with two rows of setae; length of labrum ½ times of width. Hypopharynx ( Fig. 43 ): lingua with well developed lateral processes, with anterior margin cleft; superlingua with row of setae on anterior margin. Mandibles ( Figs 44–45 ): translucent, incisors and molars dark brown; scattered setae and tuft of setae laterally, inner incisor longer than outer one. Maxilla ( Fig. 46 ): Segment I of maxillary palp longer than segment II, segment II shorter than segment III, segments I and III subequal in length, segment III with long setae at apex; outer margin of segment II with long setae; inner margins of segments II and III with short setae. Labium: palps 3-segmented, segment I broader with thick lateral setae, segments II and III subequal in length, segment III tapering at apex with a row of 5 conspicuous setae on the dorsal surface ( Fig. 47 ).

Thorax. Pale yellowish brown, irregularly washed with dark brown; lateral margins of pronotum pale yellow with diffuse black markings ( Fig. 38 ). Legs pale yellow; coxae brown; all femora with large mesal macula dorsally. Foreleg ( Fig. 48 ): outer surface of femur with rows of thick and scattered hair-like setae; inner surface with two rows of small stout setae, four prominent stout setae directed towards the distal end; inner surface of tibia with thick setae. Midleg ( Fig. 49 ): dorsal surface of femur with 3 rows of short thick setae; row of short stout setae on midline; inner surface with two rows of small stout setae; tibia with rows of short setae. Hindleg ( Fig. 50 ): femur with median brown macula on outer surface, with rows of thick and scattered hair-like setae; dorsal surface with 3 rows of short setae; inner surface with two rows of small setae; inner surface of tibia with thick setae; outer surface with few hairlike setae. Claws with 7–10 denticles which progressively increase in size apically ( Fig. 51 ).

Abdomen. Terga I–X yellowish brown with black posterior margins; terga I–X with yellowish stripe medially; posterolateral spines on abdominal segments IV–IX progressively larger posteriorly, segments VII–IX with pointed spines ( Fig. 39–40 ). Gills on segments I–VII; gill I slender, lanceolate and bifid without branched tracheae; gills IV– VI broader from the base to middle, tapering distally ( Figs 52–53 ). Subanal plate deeply cleft ( Figs 55–56 ). Terminal filament longer than cerci; caudal filaments with setae of each segment, shorter than length of corresponding segment.

Adult: Unknown.

Etymology: This species is named after the mythological Hindu sage Agasthya, who is believed to reside in the hills of the Southern Western Ghats from where the type specimens were collected. Treat as noun in apposition.

Distribution: Peppara wildlife sanctuary, Kerala, India.

Diagnosis: Megaglena agasthiya n. sp. can be differentiated from the only species, M. brincki Peters & Edmunds (1970) from Sri Lanka by the following character: (i) hind femur with dark band at mid length ( Fig. 50 ), in contrast to M. brincki , which has dark band subapically ( Peters & Edmunds 1970).

Habitat: Larvae of Megaglena agasthiya n. sp. inhabit a small (from 2–3 m wide) mountain stream (Pandipath stream) which is typical in the upper mountain zone (up to 1320 m a.s.l.) of the Peppara Wildlife Sanctuary, Trivandrum District, Kerala ( Fig. 60 ). The stream is characterized by medium water temperature (18–20°С at the time of sampling), average current velocity and sandy bottom with leaf litter. The new species were found with the larvae of the Choroterpes sp. , Baetis sp. and Dudgeodes sp.

Discussion: Genus Megaglena was established by Peters & Edmunds (1970) based on collections of larvae and adults from several localities in Sri Lanka during Swedish Ceylon expedition from Lund University Sweden in 1962. Peters & Edmunds (1970) has given diagnostic generic features of Megaglena Peters & Edmunds 1970 based on study of larvae and respective adults collected from the same locality. The present description of Megaglena agasthiya n. sp. from southern Western Ghats streams in Kerala state of India is extension of the generic range north of Sri Lanka in adjacent southern India. Interestingly, presence of a row of setae interspersed with spines on the outer margins of fore femora is a character shared with Edmundsula Sivaramakrishnan 1985 of southern India and Sangpradubina Boonsoong & Sartori 2016 of Thailand. The phylogenetic relationships of Gondwanan atalophlebiid genera can be understood only when integrated morphological and molecular studies of this cluster of genera are undertaken as pointed already.

Figures

FIGURES 38–43. Larva of Megaglena agasthiya n. sp. 38. Dorsal view; 39. Ventral view; 40. Abdomen ventral view; 41. Labrum dorsal; 42. Labrum ventral; 43. Hypopharynx.

FIGURES 44–49. Larva of Megaglena agasthiya n. sp. 44. Left mandible; 45. Right mandible; 46. Left maxilla; 47. Labium; 48. Foreleg; 49. Midleg.

FIGURES 50–56. Larva of Megaglena agasthiya n. sp. 50. Hindleg; 51. Claw; 52. Gill I; 53. Gill V; 54. Gill VII; 55. Subanal plate ♂; 56. Subanal palte ♀.

FIGURES 57–60. Type locality of new species. 57. Choroterpes (C.) andamanensis n. sp.; 58–59. Edmundsula meghamalaiensis n. sp.; 60. Megaglena agasthiya n. sp.