A new mayfly species of Choroterpes (Choroterpes) Eaton, 1881 (Ephemeroptera Leptophlebiidae) from southern Western Ghats, India Author Muthukatturaja, Marimuthu Department of Zoology, Thiagarajar College, Madurai- 625009, Tamil Nadu, India. Author Balasubramanian, Chellaiah Department of Zoology, Thiagarajar College, Madurai- 625009, Tamil Nadu, India. text Zootaxa 2022 2022-04-19 5128 1 142 150 journal article 55851 10.11646/zootaxa.5128.1.9 1e693690-d152-4c81-b391-44399a71d6dc 1175-5326 6479674 F83029DC-D657-4D18-81B9-C1360EAA23C5 Choroterpes ( Choroterpes ) kumaradhara Muthukatturaja & Balasubramanian sp. nov. (Figs 1–24) Type material (ZSI). Holotype : Final nymphal instar ( Reg.No. ZSI–SRC/ I/E 614), INDIA , Kumaradhara River , Kulkunda , Dakshina Kannada District , Karnataka state , 03.XII. 2018 , 148 m a.s.l, ( 12.680771ºN , 75.603596ºE ), colls. Muthukatturaja & Balasubramanian . Paratypes : 5 final nymphal instars ( Reg.No. ZSI–SRC/ I/E 615), same data as holotype, colls. Muthukatturaja & Balasubramanian . Other material examined (ZMTC). 10 final nymphal instars (ZMTC–84), INDIA , Kumaradhara River , Kulkunda , Dakshina Kannada District , Karnataka state , 03.XII. 2018 , 148 m a.s.l, ( 12.680771ºN , 75.603596ºE ), colls. Muthukatturaja & Balasubramanian. 20 final nymphal instars (ZMTC–85), INDIA , Kapila River , Parpikal , Dakshina Kannada District , Karnataka state , 02.XII. 2018 , 608 m a.s.l, ( 15.029560ºN , 76.319630ºE ), colls. Muthukatturaja & Balasubramanian. 15 final nymphal instars (ZMTC–86), INDIA , Belthangadi , Dakshina Kannada District , Karnataka state , 31.III. 2018 , 108 m a.s.l, ( 12.871930ºN , 74.832540ºE ), colls. Muthukatturaja & Balasubramanian. 20 final nymphal instars (ZMTC–87), INDIA , Payaswini river , Sampaje , Kodagu district , Karnataka state , 30.III. 2018 , 152 m a.s.l, ( 12.500499ºN , 75.540962ºE ), colls. Muthukatturaja & Balasubramanian. 20 final nymphal instars (ZMTC–88), INDIA , Tunga River , Sringeri , Chikkamagalore district , Karnataka state , 01–IV– 2018 , 669 m a.s.l, ( 13.426900ºN , 75.255100ºE ), colls. Muthukatturaja & Balasubramanian. 25 final nymphal instars (ZMTC–89), INDIA , Sharavathi stream (Kollur), Udupi district , Karnataka state , 21.V.2019 , 87 m a.s.l, ( 13.858122ºN , 74.818868ºE ), colls. Muthukatturaja & Balasubramanian. 10 final nymphal instars (ZMTC– 90), INDIA , Shiroor, Udupi district , Karnataka state , 21.V.2019 , 87 m a.s.l, ( 13.962201ºN , 74.681432ºE ), colls. Muthukatturaja & Balasubramanian . Description. Final nymphal instar (Fig. 1): Body length (excluding cerci) 5.5–6.5 mm in male and female nymphs; cerci 7.0– 7.5 mm ; median terminal filaments 8.0– 8.5 mm ; head width 1.3 mm ; head length 0.9 mm ; antenna length 2.0 mm; labrum width 0.7 mm ; labrum length 0.3 mm ; compound eye length 0.35 mm ; compound eye width 0.25 mm ; distance between compound eye 0.2 mm ; length of fore femur/ tibia/ tarsi 1.3/ 1.3/ 0.5 mm ; length of middle femur/ tibia/ tarsi 1.3/ 1.2/ 0.35 mm ; length of hind femur/ tibia/ tarsi 1.7/ 1.4/ 0.4 mm . General body coloration grey to yellowish brown. FIGURES 2–7. Choroterpes ( Choroterpes ) kumaradhara sp. nov. , final nymphal instar. 2, labrum; 3, labrum (median line of long setae focused); 4, labrum (median emargination focused); 5, left mandible; 6, right mandible; 7, hypopharynx. FIGURES 8–12. Choroterpes ( Choroterpes ) kumaradhara sp. nov. , final nymphal instar. 8, left maxilla; 9, right maxilla; 10, 3 rd segment of maxillary palp; 11, labium; 12, 3 rd segment of labial palp. Head. Dark grey to yellowish-brown; scape and pedicel of antennae pale grey, flagellum translucent; upper portion of compound eyes reddish-brown, lower portion black; upper portion of ocelli white, lower portion black. Labrum (Fig. 2): two times longer than wide; emargination deeply cleft (U-shaped) with few denticlelike protuberances and a row of long biserrated setae (Fig. 4); dorsal surface with sparse thin setae and a row of very long setae medio-laterally (Fig. 3); lateral margins smoothly curved with a row of stout setae. Mandibles (Figs. 5 & 6): inner and outer incisors trifurcated; median of lateral margin with a group of thin, long setae; right mandible with 9–12 thin, long setae below mola (Fig. 6) and prostheca with well developed biserrated processes; left mandible prostheca with incisor-like apparatus denticulated apically and well developed biserrated processes (Fig. 5). Hypopharynx (Fig. 7): lingua deeply cleft; lateral margin of superlingua angularly curved; anterior margin with rows of thin setae. Maxilla (Figs. 8 & 9): apex of galea-lacinia with row of comb-like setae and cluster of thin setae; anterior margin covered with cluster of thin, long setae; inner margin with row of long feathered setae; palp three segmented, segment I and II sub equal in length; segment III smaller than others; outer margin of segment I with a stout setae and few hair-like setae; inner and outer margins of segment II with few long hair-like setae; distal ½ of segment III with cluster of thin setae; proximal ½ of inner margin with row of thin long setae (Fig. 10). Labium (Fig. 11): glossae rounded with apical spines and sparse thin setae; paraglossae covered with thin setae; labial palp three segmented, segment I longer than segment II and III, with a row of stout setae at inner and outer margins; inner and outer margins of segment II with few thin, long setae; segment III sparsely covered with thin setae and a transversal row of stout spines (Figs. 12). Thorax. Yellowish-brown to pale-yellow; pronotum wider than head with 2–4 spines at anterior margin; legs yellowish-brown with grey bands; surfaces covered with long hair-like setae; foreleg (Fig. 13) coxae with a spine at outer margin; trochanter with 2 spines at inner margin; outer margin of femur with a row of long spatulate setae and stout spines; basal ½ of inner margin with 2 rows of stout spines; median of inner margin of tibia with rows of monopectinate setae (Fig. 16); inner-distal margin with few long bipectinate setae and monopectinate setae; inner margin of tarsi with a row of short spines; claw slender, slightly curved with 10–12 denticles (Fig. 17); midleg (Fig. 14) coxae similar to foreleg; trochanter with a row of 5 spatulate setae at inner margin; outer margin of femur with a rows of long and short spatulate setae (Fig. 18); inner and mesal margins with rows of spatulate setae; inner margin of tibia with a row of spatulate setae and short spines; tarsi and claw similar to foreleg; hindleg (Fig. 15) coxae and tronchanter similar to foreleg; femur similar to midleg; inner and outer margin of tibia with rows of spatulate setae and stout spines; tarsi and claw similar to foreleg. Abdomen. Grey to pale yellow; terga II–IX with a macula on either side of mesal margin; posterolateral spines present on segments II–IX progressively longer posteriorly (Fig. 23); sterna pale; gills grey, trachea grayish-black; gill I single lamellate, basal half broader and tapered to apex (Fig. 19); gills II–VII double lamellate (Fig. 20); median projection of dorsal lamella of gills II–VII plate-like and markedly larger and longer than laterals (Fig. 21); ventral lamella of gills II–VII smaller than dorsal lamella and trifurcated (Fig. 22); paracercus and cerci pale yellow, paracercus little longer than cerci. FIGURES 13–18. Choroterpes ( Choroterpes ) kumaradhara sp. nov. , final nymphal instar. 13, foreleg; 14, midleg; 15, hindleg; 16, foretibia; 17, femur enlarged for spatulate setae; 18, tarsal claw. FIGURES 19–23. Choroterpes ( Choroterpes ) kumaradhara sp. nov. , final nymphal instar. 19, gill I; 20, gill III; 21, dorsal lamella of gill III; 22, ventral lamella of gill III, 23, abdomen. FIGURE 24–Habitat of Choroterpes ( Choroterpes ) kumaradhara sp. nov. Etymology. The new species is named after the type locality: Kumaradhara River, Dakshina Kannada District, Karnataka . Adults. Unknown. Distribution. Western Ghats, India . Diagnosis. Choroterpes ( Choroterpes ) kumaradhara sp. nov. can be distinguished from other Oriental species of Choroterpes s.str. by the following combination of characters: (i) median emargination of labrum deeply cleft (Ushaped) with few denticle-like protuberances (Fig. 2); (ii) the lateral margin of mandibles with a cluster of thin, long setae medially (Figs. 5 & 6); (iii) gill I single lamellate, basal half broader and tapered to apex (Fig. 19); (iv) median projection of dorsal lamella of gills II–VII plate-like and markedly larger and longer than laterals, ventral lamella small, trifurcated (Fig. 20–22); and (v) abdominal segment II–IX with posterolateral spines progressively longer posteriorly (Fig. 23). Habitat. The nymphs of Choroterpes ( Choroterpes ) kumaradhara sp. nov. were collected from the slowflowing areas of permanent streams (Fig. 24). Water and air temperatures of the collection sites ranged 23– 26ºC. The current velocity was approximately 0.2–0.5 m /s. Water depth ranged 10–30 cm . The substratum was mainly composed of boulders, cobbles and pebbles. The new species associated with other mayfly genera are Clypeocaenis sharadhae Balasubramanian & Muthukatturaja, 2020 and Caenis sp. (Caenidae) , Teloganodes sp. (Teloganodidae) , Rhoenanthus tungaiensis Balasubramanian & Muthukatturaja, 2019 (Potamanthidae) , Isonychia radhae Balasubramanian & Muthukatturaja, 2021 (Isonychiidae) , Baetis sp. (Baetidae) , Thraulus thiagarajani Balasubramanian & Muthukatturaja, 2019 and Indialis sp. (Leptophlebiidae) .