Contribution to the study of Epeorus Eaton, 1881 (Ephemeroptera: Heptageniidae) from India Author Vasanth, M. 0000-0003-4446-4889 Zoological Survey of India, Southern Regional Centre, Santhome High Road, Chennai- 600028, India. & University of Madras, Chepauk, Chennai- 600005. & vasan 071994 @ gmail. com; https: // orcid. org / 0000 - 0003 - 4446 - 4889 vasan071994@gmail.com Author Selvakumar, C. 0000-0002-4296-5682 Department of Zoology, The Madura College (Autonomous), Madurai- 625011, Tamil Nadu. & selvaaa 06 @ gmail. com; https: // orcid. org / 0000 - 0002 - 4296 - 5682 selvaaa06@gmail.com Author Subramanian, K. A. Zoological Survey of India, Southern Regional Centre, Santhome High Road, Chennai- 600028, India. Author Sivaramakrishnan, K. G. 0000-0002-6332-0349 Flat No 3, Door No 7, Gokulam Apartment, Gokulam Colony, West Mambalam, Chennai- 600 033, India. & kgskrishnan @ gmail. com; https: // orcid. org / 0000 - 0002 - 6332 - 0349 kgskrishnan@gmail.com Author Sinha, Bikramjit 0000-0002-9904-4964 Zoological Survey of India, Arunachal Pradesh Regional Centre, Senki Valley, Itanagar- 791113, Arunachal Pradesh, India. & sinhabj @ gmail. com; https: // orcid. org / 0000 - 0002 - 9904 - 4964 sinhabj@gmail.com text Zootaxa 2021 2021-06-25 4991 3 499 522 journal article 10.11646/zootaxa.4991.3.4 1175-5326 5042522 842EA450-A680-4D5D-9723-C1D7CCE13E5D Epeorus ( Epeorus ) bifurcatus Braasch & Soldán, 1979 ( Figs 18–34 ) Material examined: 2 larvae , India , Arunachal Pradesh , West Kameng , Dirang , Showda village , Dirang river , 27.3267528 N , 92.2318027 E , 1877 m , 13.iii.2018 , coll. Bikramjit Sinha [ZSI/ SRC-I /E/297] ; 1 larva , India , Arunachal Pradesh , Upper Dibang Valley , Mipi , Mipi river , 28.96643 N , 95.8061 E , 1455 m , 31.x.2017 , coll. Anil Kumar & Party [ZSI/ SRC-I /E/312] ; 15 larvae , India , Arunachal Pradesh , West Kameng district , Sangti valley , Khechalu , Khendo Rong (stream), 27.420841 N , 92.269538 E , 1790 m , 12.iii.2018 . coll. Bikramjit Sinha [ZSI/ SRC-I /E/320] . Description: Larva: Body length 9.8 mm ; length of cerci 10.4 mm . Body generally dark brown ( Fig. 18 ). Head: Length 1.7 mm , width 2.9 mm ; light brown ( Fig. 18 ); subquadrangular; anterior and lateral margins convex, with rows of hair-like setae directed anteriorly. Compound eyes black. Antennae with scape, pedicels and flagella light brown ( Fig. 22 ). Labrum brown with deep median notch on anterior margin, long hair-like setae laterally ( Fig. 23 ). Hypopharynx as in Fig. 24 . Mandibles without scattered setae along the molar area; incisors serrated, outer incisor longer than inner incisor ( Figs 25–26 ). Maxilla as in Fig. 27 . Labium ( Fig. 28 ) as in the previous species. Thorax: Pronotum pale brown with indistinct band in middle and pair of dark spots; mesonotum brown ( Fig. 18 ). Legs ( Figs 29–31 ): Femora light brown, hypodermal spot on middle, outer margin with long setae and dark brown maculae medially; distal end with blunt spine; dorsal surface with scattered stout short thickened setae ( Fig. 31a ); tibia pale brown with long hair-like setae on outer margin; claw with 3 small denticles ( Fig. 32 ). Abdomen: Abdominal terga light brown, terga II–IX with pair of short submedian spines ( Figs 18, 20 ); tergum II yellowish, terga III and IV with indistinct pale patches on middle, terga V–VIII with light middle band; terga II–IX with small setae along midline ( Fig. 21 ); segments II–VII with long postero-lateral extensions; sterna light yellowish without markings ( Fig. 19 ). Gill I triangular ( Fig. 33 ); gills II–VII oval ( Fig. 34 ). Cerci with row of hairlike setae dorsally. Diagnosis: The larva of Epeorus ( E. ) bifurcatus can be distinguished from other species of this genus by the following combination of characters: (i) posterior margin of abdominal terga II–IX with pair of short submedian spines ( Figs 18 & 20 ); terga II–IX with small setae along midline ( Fig. 21 ); and (iii) gill I larger than others ( Fig. 33 ). Distribution: Vietnam , Thailand and India ( Arunachal Pradesh ). Remarks: The larva of this species was described from Vietnam by Braasch & Soldán (1979). Subsequently, Nguyen & Bae (2004) redescribed the larva of E. bifurcatus based also on specimens from Vietnam . Braasch & Boonsoong (2010) reported this species from Thailand ; we provide a supplementary larval description based on our material, which represents the first record of the species for India .