Procloeon (Procloeon) kottagudiensis Balasubramanian & Muthukatturaja, 2022 (Fig. 3I)

Procloeon (Procloeon) kottagudiensis Balasubramanian & Muthukatturaja, 2022, 5094:322, Holotype ♂ imago, Kottagudi stream, Tamil Nadu, India.

Material examined. 3 larvae, Moolaiyaru River, 10°16'13" N, 77°36'34" E, 1217 m, 27-iv-2023; 4 larvae, Thaliyuthu Water Falls, 10°26'33" N, 77°41'09" E, 346 m, 02-vii-2023; 3 larvae, Nalla Thangal Stream, 10°23'58" N, 77°36'49" E, 586 m, 02-vii-2023; 17 larvae, Varaiyaru Falls, 10°19'41" N, 77°42'54" E, 1172 m, 01-vii-2023; 15 larvae, Umaiyaru River, 10°20'56" N, 77°41'27" E, 1236 m, 01-vii-2023, Coll. C. Selvakumar & party.

Distribution. India: Kerala and Tamil Nadu (Muthukatturaja & Balasubramanian, 2022).

The following four mayfly species: Megaglena agasthiya, Choroterpes (Euthraulus) atelobranchis, Caenis maduraiensis and Nigrobaetis klugei are reported for the first time from the Palni Hills. The endemic species Megaglena agasthiya and Nathanella indica were found only in the high elevation sites (above 1670 m), whereas Isca sp. and Teloganodes (Dudgeodes) palnius were found in low elevation sites (353 m) as well as high elevation site (1685 m). The oriental species, Ecdyonurus (Rhithrogeniella) ornatus occurs in the moderate high elevation ranges between 1217 m and 1236 m. Ephemera (Aethephemera) nadinae is found at only one high elevation site (1271 m), which is characterised by slower water current and sandy bottom. In contrast, other mayflies exhibit overlapping distributions across different altitudes (Table 2). Out of 24 species distributed throughout Palni Hills, 12 occur in the low to moderate elevation study sites. Megaglena agasthiya, Isca sp., and Nathanella indica are distributed only in the southern Palni Hills, whereas Baetis (Tenuibaetis) frequentus is only distributed in the northern Palni Hills. Caenis americani occurs only in the southern Palni Hills, whereas Caenis maduraiensis is only found in the northern Palni Hills. The number of individuals and richness of species is decreasing with the increasing elevation, while the abundance of species and elevation are negatively correlated (r=0.26) (Fig. 4).