Two new species of the genus Thalerosphyrus Eaton, 1881 (Ephemeroptera: Heptageniidae: Ecdyonurinae) from India Author Vasanth, M. Southern Regional Centre, Zoological Survey of India, Chennai- 600 028, India. Author Kubendran, T. Zoological Survey of India, Prani Vigyan Bhavan, M-Block, New Alipore, Kolkata- 700 053, India. Author Subramanian, K. A. 0000-0003-0872-9771 Southern Regional Centre, Zoological Survey of India, Chennai- 600 028, India. subbuka.zsi@gmail.com Author Babu, R. 0000-0001-9147-4540 Southern Regional Centre, Zoological Survey of India, Chennai- 600 028, India. baburzsi@gmail.com text Zootaxa 2025 2025-02-03 5583 2 247 270 https://doi.org/10.11646/zootaxa.5583.2.2 journal article 307989 10.11646/zootaxa.5583.2.2 564b2519-5ebe-4838-a0d1-c00f7f1609e9 1175-5326 14798053 E5168208-01D7-4218-BE79-67B2E0E61E5E Larval key to the genus Thalerosphyrus from India 1. Posterolateral expansions of abdominal segments well developed on III–VIII and directed outwards ( Figs 97–98 ); pronotum greatly enlarged laterally and posteriorly ( Fig. 96 ); anterior margin of the labrum with a smooth, shallow depression in the middle area ( Fig. 99 )........................................................................... T. flowersi - Posterolateral expansions of abdominal segment III–VIII moderately developed ( Figs 4–5 , 53–54 ); pronotum is moderately enlarged laterally and posteriorly ( Figs 4–5 , 51 ); labrum a different shape......................................... 2 2. Posterior margins of terga with irregular pointed teeth and a row of microdenticles ( Figs 84–86 ); hind tibia with two rows of thin setae on the dorsal face of hind femora arrow-shaped......................................................3 - Posterior margin of tergites with regular pointed teeth, and numerous microdenticles ( Selvakumar et al. 2017 : Fig. 21 ); hind tibia with one row of thin setae; setae on the dorsal surface of hind femora truncate or rounded at apex ( Selvakumar et al . 2017 : Fig. 15 )............................................................................... T. meghalayensis 3. Hind femur dorsal surface with arrow-shaped, blunt and strong setae ( Fig. 40 ); labrum expanded laterally, 4.5× wider than long, anterior margin straight, medially bulged with a concave shape and small blunt crenations on either side, ( Fig. 12 )........................................................................................... T. bengalensis sp. nov. - Hind femur dorsal surface with arrow-shaped setae, clearly point ( Fig. 75 ); Labrum moderately broad, 3.5× wider than long, anterior margin straight ( Figs 57–58 )....................................................... T. sartorii sp. nov.