Redescriptions of Indian species of Nigrobaetis Kazlauskas (in Novikova & Kluge) 1987 (Ephemeroptera, Baetidae).

The European species Nigrobaetis gracilis (Bogoescu & Tabacaru 1957) and more than 19 Asian and African species of Nigrobaetis Kazlauskas (in Novikova & Kluge) 1987 belong to the subgenus Margobaetis Kang & Yang 1994, which is characterized by peculiar asymmetric eggs and narrow paraglossa of larval labium. A new synonymy is established: Nigrobaetis (Margobaetis) minutus (Mller-Liebenau 1984) = N. paramakalyani Kubendran & Balasubramanian in Kubendran et al. 2015 = N. sumbensis Kaltenbach & Gattolliat 2023, synn.n.; winged stages (male and female imagines and subimagines) and eggs of this species are described for the first time. N. (M.) minutus is widely distributed on Oriental Region, being revealed in West Malaysia, Southern India, Sumba and Sulawesi islands in Indonesia. Winged stages (male and female imagines and subimagines) and eggs of Nigrobaetis (Margobaetis) klugei Sivaruban et al. 2022 are described for the first time.

Redescription of the subgenus Rhithrogeniella Ulmer 1939 (Ephemeroptera, Heptageniidae, genus Ecdyonurus) based on reared specimens from India and Thailand.

Rhithrogeniella Ulmer 1939 is treated here as a subgenus of the genus Ecdyonurus Eaton 1868 (s. l.). The subgeneric name Rhithrogeniella is a senior synonym of Afghanurus Demoulin 1964 syn. n., Paracinygmula Bajkova 1975 syn. n. and Nixe Flowers 1980 syn. n. Additional description of Ecdyonurus (Rhithrogeniella) ornatus (Ulmer 1939) is given based on imagines and subimagines of both sexes reared from larvae in India and Thailand; lectotype of this species name is designated. Synonymy of E. (Rh.) ornatus and E. (Rh.) tonkinensis Soldán & Braasch 1986 is established (syn. n.). Male and female imagines and subimagines of an unnamed species of Rhithrogeniella are reported from India.

Contribution to the knowledge of the subgenus Tenuibaetis Kang & Yang 1994 (Ephemeroptera, Baetidae, Baetis s. l.).

The taxon Tenuibaetis Kang & Yang (in Kang, Chang & Yang) 1994 is accepted here as a subgenus of the genus Baetis Leach 1815, but not as a genus. In connection with this, new combinations are established: Baetis (Tenuibaetis) parvipterus (Fujitani et al. 2011) comb. n., Baetis (Tenuibaetis) fujitanii (Kaltenbach & Gattolliat 2019) comb. n., Baetis (Tenuibaetis) himani (Kubendran et al. in Kubendran et al. 2022) comb. n., Baetis (Tenuibaetis) kangi (Kubendran et al. in Kubendran et al. 2022) comb. n. and Baetis (Tenuibaetis) panhai (Suttinun et al. 2022) comb. n. Based on reared material, imagines of both sexes and larvae of Baetis (Tenuibaetis) ursinus Kazlauskas 1963, Baetis (Tenuibaetis) hissaricus Novikova 1991, Baetis (Tenuibaetis) frequentus Müller-Liebenau & Hubbard 1985 (= Indobaetis michaelohubbardi Selva-kumar et al. 2012, syn. n.) and B. (T.) fujitanii are redescribed. B. (T.) panhai is redescribed based on subimago reared from larva. Two new species from Southern India, Baetis (Tenuibaetis) kaltenbachi sp. n. and Baetis (Tenuibaetis) bialatus sp. n. are described based on imagines reared from larvae. A new species from Thailand, Baetis (Tenuibaetis) octomaculatus sp. n. is described based on imagines reared from larvae.

Indian species of Teloganodes Eaton 1882 (including subgenera Dudgeodes Sartori 2008 and Derlethina Sartori 2008) (Ephemeroptera, Teloganodidae).

According to the classification proposed in the previous publication by Kluge, the genus Teloganodes Eaton 1882 is divided into three subgenera distinguished only by tergalii number: the subgenus Teloganodes (with 5 pairs of tergalii on uromeres II-VI), the subgenus Dudgeodes Sartori in Sartori et al. 2008 (with 4 pairs of tergalii on uromeres II-V) and the subgenus Derlethina Sartori in Sartori et al. 2008 (with 3 pairs of tergalii on uromeres II-IV). All three subgenera are represented in Southern India. Based on the new material, additional descriptions are given to the following species: T. (Teloganodes) kodai Sartori in Sartori et al. 2008 (= Teloganodes barathyae Sivaruban et al. in Martynov et al. 2022, syn. n.); Teloganodes (Teloganodes) dentatus Navás 1932 (= T. sartorii Selvakumar et al. in Selvakumar et al. 2014, syn. n.); Teloganodes (Dudgeodes) palnius (Selvakumar et al. in Selvakumar et al. 2014) (= Dudgeodes bharathidasani Anbalagan et al. 2015, syn. n.; = Dudgeodes sartorii Srinivasan et al. 2021, syn. n.; = Dudgeodes molinerii Sivaruban et al. in Martynov et al. 2022, syn. n.); Teloganodes (Derlethina) tamiraparaniae (Selvakumar et al. in Selvakumar et al. 2014). A new species T. (Teloganodes) velutinus sp. n. is described from the Western Ghats based on larvae, female imagines reared from larvae and eggs.

Contribution to the knowledge of the family Caenidae (Insecta: Ephemeroptera) from Madurai District, Tamil Nadu.

Three new species of Caenis Stephens viz., Caenis kaegies sp. n., C. venkataramani sp. n., and C. arunachalami sp. n., are described based on larvae and reared subimagines and/or imagines from Madurai, Tamil Nadu. Two more species of Caenis are recognized and described (from eggs and imagoes) but are not formally named. Additional characters are mentioned for C. americani Srinivasan, Sivaruban, Barathy, Malzacher & Isack, 2021 and C. maduraiensis Balasubramanian & Muthukatturaja, 2021. The egg morphology of all the known species of Caenis from Tamil Nadu is described. The total number of Caenis species is thereby increased to seven in the Madurai District and nine in South India. The genus Clypeocaenis Soldan is recorded for the first time in the Madurai District, with the species Clypeocaenis kaveri Balasubramanian and Muthukatturaja, 2021, whose description is amended. Identification keys to the adults, larvae, and eggs of the known Caenis species from South India are also provided.

Diagnosis, variability, distribution and systematic position of Labiobaetis pulchellus (Müller-Liebenau & Hubbard 1985) (Ephemeroptera, Baetidae, Baetis s. l.).

A new synonymy to Labiobaetis pulchellus (Müller-Liebenau & Hubbard, 1985) (= L. soldani Kubendran et al. 2014, syn. n.) is established based on examination of imagines reared from larvae in India and Sri Lanka. This species belongs to the tricolor group, which comprises Holarctic species L. tricolor (Tshernova, 1928), L. propinquus (Walsh, 1863), L. calcaratus (Keffermüller, 1972), and some Oriental species.

Review of the subgenus Euthraulus (Ephemeroptera, Leptophlebiidae, genus Choroterpes) from the Western Ghats (India).

The subgeneric name Monochoroterpes Kluge Jacobus 2015 is regarded here to be a junior synonym of Euthraulus Barnard 1932 (syn. n.), based on a wider understanding of more species from each group. Based on male and female imagines reared from larvae, the following species are described or re-described: Choroterpes (Euthraulus) alagarensis Dinakaran et al. 2009, Ch. (E.) armillatus sp. n., Ch. (E.) latus sp. n., Ch. (E.) atelobranchis sp. n., Ch. (E.) unicolor sp. n., Ch. (E.) nambiyarensis Selva-Kumar et al. 2013, Ch. (E.) angustifolius sp. n. and Ch. (E.) nandini Selvakumar Sivaramakrishnan 2015. All these species are distributed in southern India. One of them, Ch. (E.) latus sp. n., was collected in a plains river, Vaigai, in Madurai and in several localities in Sri Lanka, including a plains river, Malvatu, in Anuradhapura; formerly it was confused with another Ceylonese species, Ch. (E.) signatus (Hagen 1858). Here the characters separating Ch. (E.) signatus from Ch. (E.) latus sp. n. are reported and illustrated. Other species listed above were collected in mountain rivers in south of Western Ghats. One more species of Euthraulus is described without a formal name based a on mature male larva collected near Mumbai. The species description of Choroterpes (Euthraulus) kalladaensis Rekha et al. 2019 was based on specimens belonging both to Indialis rossi and Ch. (E.) angustifolius; since the type specimens are lost, and the description is based mainly on characters of Indialis rossi, we propose the following synonymy: Indialis rossi Peters 1975 = Choroterpes (Euthraulus) kalladaensis Rekha et al. 2019, syn. n.

A new species of Clypeocaenis Soldn 1978 (Ephemeroptera: Caenidae) from Tamil Nadu, India.

Clypeocaenis malzacheri sp. nov. is described from the Kottakudi River in southern India, based on larvae and eggs. Clypeocaenis malzacheri sp. nov. appears to be closely related to C. bisetosa Soldn. The new species is distinguished from this species and other congeners based on the structure of the frons; the structure, setation, and maculation of legs; the shape and orientation of the abdominal tergum II projection; and by the shape and denticulation of abdominal sternum IX. Updated couplets for an identification key to Clypeocaenis larvae in the Indomalayan region are provided. The total number of Clypeocaenis species is thereby increased to twelve in the world and seven in India.

A new species of Nigrobaetis Novikova amp; Kluge, 1987 (Ephemeroptera, Baetidae) from Tamil Nadu, India.

Nigrobaetis klugei sp. nov. is described based on nymphs from the Sastha falls of Western Ghats, Southern India. The nymph of Nigrobaetis klugei sp. nov. can be distinguished from other Oriental species of Nigrobaetis by the following combination of characters: (i) dorsal surface of the labrum with 1+3 long simple stout setae on the distal half; (ii) paraproct distally not expanded, with a reduced number of spines on distal margin (three large and two small spines); (iii) paraglossae slender, approximately as wide as glossae; (iv) absence of medioproximal spots in the abdominal tergites and (v) long and pointed triangular spines at the distal margin of abdominal tergites.

The unexpected discovery of the Afrotropical genus Tricorythus Eaton, 1868 (Ephemeroptera: Tricorythidae) from the Oriental region with description of a new species.

Tricorythus meenakshi sp. n., is described based on all the stages from Tamil Nadu, Southern India. This new Indian species is most closely related to the Afrotropical species T. discolor Burmeister and T. tener Kluge. The new species can be separated from others in the genus by: In male imago, i) body dorsally with a colorless median stripe from head to abdomen; ii) femur and base of the tibia of all legs dark, rest mostly colorless; and iii) penis shape; and in the larva, i) body slender with a light median stripe as in adult; ii) protoptera dark in both sexes; iii) mouthparts details; iv) tarsal claws denticulation; and v) shape of denticles on hind margins of abdominal terga. Previously, the genus Tricorythus Eaton was known only from the Afrotropical realm; this is the first record of this genus from the Oriental realm.

Contribution to the knowledge of Teloganodidae (Ephemeroptera, Ephemerelloidea) of India.

Two new species of Dudgeodes Sartori, 2008 and a new species of Teloganodes Eaton, 1882 are described from India; they are Dudgeodesselvakumari Martynov & Palatov, sp. nov. from Himalayan region (Uttarakhand), Dudgeodesmolinerii Sivaruban, Martynov, Srinivasan, Barathy & Isack, sp. nov., and Teloganodesbarathyae Sivaruban, Martynov, Srinivasan & Isack, sp. nov. from the Tamil Nadu part of the Western Ghats. Thus, for now, the Teloganodidae fauna of India includes 11 species. Dudgeodesselvakumari sp. nov. appears to be significantly extend northward the known distribution of Dudgeodes. Partial COI sequences were used as an initial clustering method to show the relationships of D.selvakumari sp. nov. with other sequenced operational taxonomic units (OTU) of the genus.

First report of Cheleocloeon Wuillot & Gillies 1993 (Ephemeroptera: Baetidae) from the Oriental Region.

A new species, Cheleocloeon vaigaiensis sp. n., is described from Southern India based on larvae, imagines and subimagines of both sexes associated by rearing. This new Oriental species is most closely related to the Afrotropical species Cheleocloeon clavifolium Kluge 2016. Formerly, the genus Cheleocloeon Wuillot & Gillies 1993 was known only from Africa, Madagascar and Arabia; this is the first report of this genus from the Oriental Region.

A new species of Sparsorythus Sroka amp; Sold, 2008 (Ephemeroptera: Tricorythidae) from Tamil Nadu, India.

Sparsorythus srokai sp. nov. is described from the Veerapandi River, Theni district, Tamil Nadu, India based on nymphs of both sexes. The nymphs of Sparsorythus srokai sp. nov. can be distinguished by the following combination of characters: i) presence of lateral setae in each segment of caudal filaments, ii) dorsal surface of labrum entirely covered with scattered ribbon-like bristles, iii) posterior margin of mesonotum reaching abdominal segment III in both sexes, and iv) left prostheca with several pointed teeth apically. The new species is compared with other Indian species: S. gracilis Sroka Sold, 2008, S. sivaramakrishnani Sivaruban, Srinivasan, Barathy, Rosi Isack, 2021 and S. nanjangudensis Muthukatturaja Balasubramanian, 2021. The distributional map and key to the genus Sparsorythus in Southern India are also given.

A new species of Dudgeodes Sartori, 2008 (Ephemeroptera: Teloganodidae) from Megamalai hills of southern Western Ghats, India.

Dudgeodes sartorii sp. nov. is described based on nymphs from the Megamalai hills of Western Ghats, Southern India. The nymph of Dudgeodes sartorii sp. nov. can be distinguished from other Indian species of Dudgeodes by i) prothorax with two rounded tubercles; (ii) outer margin of mesothorax with simple setae; (iii) distinct maculae in the distal region of femora; (iv) transverse row of setae on fore femora narrower with blunt apex and (v) dark brownish band on the 5th segment of cerci.

A new species of Sparsorythus Sroka amp; Soldán, 2008 (Ephemeroptera: Tricorythidae) from Eastern Ghats of Southern India.

A new mayfly species, Sparsorythus sivaramakrishnani sp. nov. from the stream of Pullian cholai, Thuraiyur, Namakkal district, Tamil Nadu, India is described based on male and female nymphs. Sparsorythus sivaramakrishnani sp. nov. differs from the closely related S. gracilis by the shape of the left prostheca, the number of bristle-like processes at base of left prostheca, the ratio and shape of right prostheca, the ratio of femur length: width, the size of the female nymph, the mesonotum overlapping in fifth abdominal segment of the female, and by the shape of hypopharyngeal lingua.

A new charismatic Caenis Stephens, 1835 (Ephemeroptera: Caenidae) from Southern India.

Caenis americani sp. nov. is described based on larvae and female imagoes from the Mangalamkombu stream of Southern India. Caenis americani is most likely a parthenogenetic species, in the light of the fact that only females have been collected. The larva can be distinguished from other species of Caenis by the i) shape of the sternum IX and its shagreen field, ii) shape and denticulation of hind claws and iii) lateral lobes of mesonotum distinctly bulged. The phylogenetic relationships of the new species remain unknown, as molecular records of Caenis throughout the Oriental region are largely unknown, and the taxonomically important males are absent.