Baetiella ausobskyi Braasch, 1983

Vasanth, M., Selvakumar, C., Subramanian, K. A., Sivaramakrishnan, K. G. & Sinha, Bikramjit, 2020, New record of the genus Baetiella Uéno, 1931 (Ephemeroptera: Baetidae) from India with description of a new species and new records for five species, Zootaxa 4763 (4), pp. 563-578 : 570-572

Baetiella ausobskyi Braasch, 1983

( Figs 34–47 )

Material examined. 1 larva, INDIA, Arunachal Pradesh, Lower Subansiri district, Tale Valley Wildlife Sanctuary (TVWls), Pange stream, 27.5485 N, 93.89758 E, 1851 m, 18.vi.2017, colls. K. A. Subramanian & M. Vasanth (Reg. No. I /E/247); 2 larvae, Arunachal Pradesh, Upper Dibang Valley district , Talo river , 28.66941 N, 96.10402 E, 1323 m, 29.x.2017, coll. Anil Kumar & Party (Reg. No. I /E/248).

Mature larva. Body length 4.5–5.0 mm ( Fig. 34 ); cerci 4.5–5.0 mm, median caudal filament with 5 segments.

Head. Antennae light brown, approximately 2 times the width of head; dorsal surface of scape and pedicel with fine scattered setae. Labrum ( Fig. 35 ) rectangular, approximately 2.0 times wider than long; anteromedian notch deep with a small rounded lobe at the base, and each side with one medial long seta and a row of 6 robust, simple submarginal setae, fine and simple setae scattered posteriorly; ventrally bordered with feathered setae along the anterior margin. Hypopharynx ( Fig. 36 ) with lingua rounded and superlinguae with distal margin concave, covered with abundant fine setae. Left mandible ( Fig. 37 ): incisors fused with 7 denticles, prostheca robust with 4 blunt and 3–4 acute denticles apically. Right mandible ( Fig. 38 ): incisors with visible fusion line, outer incisor with 3 denticles and inner incisor with 4 denticles, inner incisor margin smooth without fine setae, prostheca with denticles apically and distinctly more slender than the one on left mandible, edge between prostheca and molar smooth, without serration, molar plate-like. Maxillae ( Fig. 39 ) with three canines and one dentiseta on crown of galealacinia, a row of 4–5 long basal setae and base of galealacinia without hump seta; maxillary palpus 2-segmented and terminal segment subequal with a small tip at apex. Labium ( Fig. 40 ): glossae slightly shorter than paraglossae, with a row of 8–9 stout setae along the inner margin dorsally and 2 long robust blunt setae at the apex; paraglossae approximately 2 times wider than glossae, with 3 rows of setae ventrally and 2–3 stout acute setae along the inner margin dorsally; labial palpus 3-segmented, terminal segment conical with a distinctive tip at apex; 2nd segment with an inner-apical lobe and a row of 4–5 setae along the outer margin; dorsal surface with numerous pores on the basal segment.

Thorax. Coloration dark brown, dorsum without tubercles. Posterior margin of metanotum with a protuberance medially ( Fig. 34 ). Hindwing pads reduced, approximately 2.0–2.5 times longer than wide. Legs slightly paler than thorax, femora creamy shaded with light brown medially and a brown longitudinal stripe near dorsal margin, tibiae and tarsi brown. Femora with a row of dense, long and simple setae on dorsal margin, approximately 1/2 of femur width; femoral villopore reduced; tibiae with irregular row of dense, fine, simple setae dorsally; tarsi with a row of sparse, fine, simple setae dorsally and a row of 6–7 robust, pointed setae ventrally increasing in length towards apex ( Figs 41–43 ); tarsal claw with a row of 6–7 denticles ( Fig. 44 ). All legs without coxal gill.

Abdomen. Dorsally brown except segments IX–X. Abdominal terga I–VIII brown each with a pair of dark brown elongate-oblique medioanterior sigilla and tergum IX–X with pair of longitudinal brown stripes near median line. Posterior margin of terga I–VIII each with a single posteromedian protuberance ( Fig. 34 ); terga surface without round scale-like and fine setae, terga VI–IX posterior margin with blunt denticles. Abdominal sterna generally yellowish-white; posterior margins of sterna I–X smooth, without any denticles or scale-like setae. Gills on segments I–VII, oval and without visible tracheation, surface scattered with numerous pores, margin smooth with fine simple setae, coloration white or reddish depending on the type of habitats ( Fig. 45–46 ). Paraproct with numerous pores on surface and 10–12 serrations along the inner margin ( Fig. 47 ). Median caudal filament reduced to one segment, cerci equal to the body length ( Fig. 34 ).

Diagnosis. Baetiella ausobskyi Braasch can be distinguished from other species of this genus by the following combination of characters: (i) terga I–VIII each with a single posteromedian protuberance ( Fig. 34 ); (ii) dorsum of labrum with a row of less than 7 robust submarginal setae ( Fig. 35 ); and (iii) 2nd segment of labial palp with small inner-apical lobe ( Fig. 39 ).

Distribution. India (Arunachal Pradesh) ( Fig. 81 ) and Nepal ( Braasch, 1983).

Remarks. Braasch (1983) described Baetiella ausobskyi based on the larvae from Nepal. Here we provide an improved larval description of B. ausobskyi , based on fresh material from our collections. Our new data represent the first report of this species from India. Our present study is made to larval description based on 3 larvae collected from streams and rivers of Arunachal Pradesh in India.

Figures

FIGURES 81. Distribution map of Baetiella in Arunachal Pradesh, India.

FIGURES 34–47. Larva of Baetiella ausobskyi Braasch, 1983. 34. Habitus in dorsal view; 35. Labrum; 36. Hypopharynx; 37. Left mandible; 38. Right mandible; 39. Maxilla; 40. Labium; 41. Foreleg; 42. Midleg; 43. Hindleg; 44. Hindclaw; 45. Gill I; 46. Gill V; 47. Paraproct.