Nigrobaetis paramakalyani Kubendran & Balasubramanian

Kubendran, T., Balasubramanian, C., Selvakumar, C., Gattolliat, J. L. & Sivaramakrishnan, K. G., 2015, Contribution to the knowledge of Tenuibaetis Kang & Yang 1994, Nigrobaetis Novikova & Kluge 1987 and Labiobaetis Novikova & Kluge 1987 (Ephemeroptera: Baetidae) from the Western Ghats (India), Zootaxa 3957 (2), pp. 188-200 : 193-195

Nigrobaetis paramakalyani Kubendran & Balasubramanian n. sp.

Figs. 22–39

Material examined. Holotype: male larva, INDIA, Tamil Nadu, Tirunelveli, Sivasailam, Gadana river, 0 8o 47’17.03”N, 77o20’49.51”E, 104 m, 28.vi.2012. Colls. C. Balasubramanian, T. Kubendran and C. Selvakumar. Paratypes: 5 male larvae and 8 female larvae, same data as holotype.

Mature Larva. Maximal length: Body 4.0 mm; cerci 3.0 mm; terminal filament shorter in female than in male. Coloration: Head yellowish-brown, antennae light yellow; prothorax brownish, mesothorax and metathorax light brown, legs light brown with a dark brown band on femora; abdominal tergites II, III and V to VII medium brown, generally with three medioproximal ecru spots; tergites I and IX uniformly ecru to light brown; tergites IV and VIII ecru with two medioproximal brown spots; tergite X ecru proximally and brown distally ( Fig. 22 ). Abdominal sternites light brown ( Fig. 23 ). Cerci ecru to light brown with two median dark brown bands.

Head: Distal lobe of antennal scape absent ( Fig. 24 ). Labrum ( Fig. 25 ): rounded with an anteromedial emargination, dorsally with three long simple stout setae in the distal half; subapical row of feathered setae on anterior margin; ventral surface with two kinds setae on distal margin: 8 to 10 lateral ones long and divided into a brush and median ones shorter and slightly feathered. Hypopharynx ( Fig. 26 ): lingua covered with small simple setae; superlingua with thin setae apically and laterally. Left mandible ( Fig. 27 ): with incisors composed of 7 denticles; prostheca with 7 denticles and a comb-shaped structure; margin between prostheca and mola with 5 tiny pointed spines; tuft of setae at apex of mola absent. Right mandible ( Fig. 28 ): with incisors composed of 7 denticles; prostheca with 7 denticles; margin between prostheca and mola with 6 medium pointed spines; tuft of setae at apex of mola present. Maxilla ( Fig. 29 ): palp two- segmented; segment 2 extending beyond galealacinia; segment 1 equal to segment 2; segment 2 apically rounded covered with 12–16 thin setae. Labium ( Fig. 30 ): glossae subequal in length to paraglossae, inner margin of glossae with a row of 7–9 setae; paraglossae 1.4 times wider than glossae, falcate, with long and stout setae; labial palp three-segmented, segment 1 without setae; segment 2 slightly produced inward to form a moderately expanded lobe at distal corner, dorsally with a row of 3 medium setae; segment 3 apically blunt to slightly concave with numerous short setae.

Thorax: Legs: dorsal margin of femora with about 7 stout setae, femoral villopore absent, ventral margin with stout pointed setae increasing in length towards the apex, lateral surfaces bare; dorsal margin of tarsi with about 7 stout setae, ventral margin with pointed stout setae ( Fig. 31 ); tarsal claw with a single row of about 11 denticles ( Fig. 32 ). Hindwing pads present ( Fig. 33 ).

Abdomen: Single lamellate gills on segments 1–7; transparent with rudimentary tracheae; gill 1 ( Fig. 34 ) small compare to other gills ( Fig. 35 ). Paraproct with very few scale bases, margins with about 2 large pointed teeth and 3 small ones; postero-lateral extension with a few scale bases, margin with numerous slender teeth ( Fig. 36 ). Posterior margin of tergum with long pointed spines ( Fig. 37 ). Two dark bands on cerci ( Figs 38, 39 ); terminal filament shorter in female ( Fig. 38 ) than in male ( Fig. 39 ).

Imago: Unknown

Diagnosis. Nigrobaetis paramakalyani n. sp. can be differentiated from other Oriental species of Nigrobaetis by the following combination of characters: (i) presence of hindwing pads ( Fig. 33 ); (ii) seven pairs of gills ( Figs 34, 35 ); (iii) paraproct with a reduce number of spines on distal margin (two large and three small spines) ( Fig. 36 ); (iv) segment 3 of labial palp truncated or slightly concave ( Fig. 30 ); (v) margin between prostheca and mola of both mandibles with reduced number of spines ( Figs 27, 28 ); (vi) contrasted pattern of the abdominal tergites ( Fig. 22 ).

Etymology. The new species is named after the presiding deity of the temple in the type locality.

Discussion. The genus Nigrobaetis comprises around 30 species, from the Palaearctic (12 species), Oriental (13 species) and Afrotropical (5 species) realms ( Barber-James et al. 2013). Nigrobaetis paramakalyani n. sp. differ from all the Oriental species by the number and shape of the spines of the paraproct; from N. candidus ( Kang & Yang 1996) by the number of gills (7 vs 6 pairs); from N. minutus ( Müller-Liebenau 1984) and N. facetus ( Chang & Yang 1994) by the presence of hindwing pads; from N. candidus ( Kang & Yang 1996) , N. gombaki (Müller- Liebenau 1984), N. gracilentus ( Chang & Yang 1994) , N. mirabilis ( Müller-Liebenau 1984) , N. taiwanensis (Müller-Liebenau 1985) and N. tatuensis (Müller-Liebenau 1985) by the shape of the segment 3 of the labial palp ( Müller-Liebenau 1984, 1985; Kang et al. 1994; Kang & Yang 1996). N. paramakalyani possesses a very distinctive colouration and pattern, as found in N. minutus Müller-Liebenau 1984 . Other diagnostic characters are very similar between the two species except the presence/absence of hindwing pads ( Müller-Liebenau 1984).

The present discovery of a new species from the Indian subregion of the Oriental realm has extended the known range of the genus in the Orient from West Malaysia westwards to southern India. The biogeographic assumption of Gattolliat (2004) that the presence of this genus in India or Sri Lanka is not confirmed but likely, indeed become a reality. Gattolliat (2004) also opines that with regard to the specific diversity of the genus in the different parts of its distribution area, it is reasonable to assume a Palaearctic or Oriental origin. According to him the presence of Nigrobaetis in southern Africa and in Madagascar is probably the result of a step-by-step colonization from northern Africa to southern Africa and finally Madagascar and that it is likely that the colonization of Madagascar took place after its break-off from the Gondwana mainland (ca 165 My), implying overseas colonization of more than 300 km ( Gattolliat 2004). The morphological similarity between N. paramakalyani and N. minutus from Southeast Asia seems to indicate Asian affinities rather than an old Gondwanian origin. Molecular phylogenetic studies of the genus Nigrobaetis from different biogeographic areas would greatly help to solve this puzzle and determine the colonizing force.

Ecology. The larvae were collected in a small perennial river, Gadana, Tirunelveli District, Tamil Nadu, India, (9–10 m wide and 2–3 m depth) with slow water current (0.4m /s) on the Eastern part of southern Western Ghats. The water temperature ranged between 22˚C–25˚C (seasonal variations) and the pH between 6.5–7.4. The collecting site is adjacent to the Paramakalyani temple, Sivasailam. The substratum is mainly gravel with patches of grasses.

Figures

FIGURES 22 – 32. Larva of Nigrobaetis paramakalyani n. sp. 22, Dorsal view; 23, Ventral view; 24, Antenna; 25, Labrum (left: dorsal; right: ventral); 26, Hypopharynx; 27, Left mandible; 28, Right mandible; 29, Maxilla; 30, Labium; 31, Foreleg; 32, Claw.

FIGURES 33 – 39. Larva of Nigrobaetis paramakalyani n. sp. 33, Hindwing pad; 34, Gill 1; 35, Gill 4; 36, Paraproct; 37, Posterior marginal spines of terga; 38, Caudal filaments of female; 39, Caudal filaments of male.