Clypeocaenis sharadhae Balasubramanian & Muthukatturaja, 2020

Muthukatturaja, Marimuthu, Balasubramanian, Chelliah & Murugan, Alagumalai, 2020, Two new species of Clypeocaenis (Ephemeroptera: Caenidae) from Western Ghats, Southern India, Zootaxa 4722 (4), pp. 361-370 : 365-369

Clypeocaenis sharadhae Balasubramanian & Muthukatturaja , sp. nov.

( Figures 2 , 17–35 )

Material examined. Holotype (in ethanol): male imago (reared from nymph) (Reg.No. ZSI–SRC/ I/E 464), India, Tunga river, Chikkamagalore district , Karnataka state, 01-IV- 2018, 669 m. (13º36′27″ N, 75º19′89″ E), collected by Balasubramanian & Muthukatturaja. Paratypes: 11 mature nymphs and one female imago, same data as holotype (Reg.No. ZSI–SRC/ I/E 465) .

Diagnosis. Clypeocaenis sharadhae sp. nov.: Nymph: (i) clypeus strongly protruded with two long setae, absence of setae on pedicel; (ii) femora with ovoid large macula; (iii) foretibia with two rows of long filtering setae on lateral margin and one row on ventral margin arranged vertically, foretarsus with transverse row of long setae, hindtibia with row of lanceolate setae on lateral margin; (iv) gills III–VI approximately triangular shaped, fringed bifid fimbriae, gill III with 12 bifurcated, 2 trifurcated fimbriae and 17 lanceolate setae at margins; (v) gill VI with 8 bifurcated fimbriae, 19 lanceolate setae on ventral margin and lack of trifurcated fimbriae; (vi) small medial projection of tergum II upright and slightly curved backwards.

Imago, male: (i) 2 cross veins in proximal half of R; (ii) C and Sc brown basally and washed brown distally, remainders translucent; (iii) vein MP forked at near ½ of distance from base to margin, fork symmetrical; (iv) penis lobes completely fused and not produced laterally; (v) absence of short bristles on the posterior margin of penis lobes.

Descriptions. Male imago ( Figs 17–21 ) (in alcohol). Body length, 1.7 mm; cerci lengths, 3.5 mm; median caudal filament, 3.7 mm; length of antenna, 0.05 mm; length of forewing, 3.3 mm; width of forewing, 1.3 mm.

Head pale brown, length 0.1 mm, width 0.4 mm; anterior margin and area around antennal base pale brown; scape and pedicel of antennae pale brown and subequal in length, flagellum translucent; dorsal diameter of eye 0.075 mm; distance between compound eyes 0.1 mm. Eyes and ocelli black.

Thorax uniformly yellowish brown, lateral margins brown. Legs translucent; length of segments in foreleg ( Fig. 18 ) femur/ tibia/ tarsus (mm) viz., 0.4/ 0.6/ 0.52; length ratio of tarsal segments (mm) viz., 0.02/ 0.25/ 0.1/ 0.1/ 0.05. Wing: Forewings ( Fig. 17 ) oval, with few cross veins; cross veins arranged singly; two cross veins at proximal half of R; C and Sc brown basally and washed brown distally, remainders translucent; vein MP forked near half distance from base to margin, fork symmetrical.

Abdomen: tergum pale yellow to translucent; sterna pale. Genitalia ( Fig. 19 ) pale yellow, forceps 0.5 mm, penis 0.6 mm; penis lobes completely fused and not produced laterally; absence of short bristles on posterior margin of penis lobes; forceps ( Fig. 20 ) formed by one segment with small bristles on surface; cerci and median caudal filament translucent.

Female imago (in alcohol). Body length, 2.7 mm; cerci lengths, 3.8 mm; median caudal filament, 4.2 mm; length of antenna, 0.3 mm; length of forewing, 3.4 mm; width of forewing, 1.4 mm.

Head brownish yellow, length 0.18 mm, width 0.4 mm; anterior margin and area around antennal base pale brown to yellow; scape and pedicel of antennae pale brown and subequal in length, flagellum translucent; distance between compound eyes 0.1 mm; dorsal diameter of eye 0.06 mm. Compound eyes and ocelli black.

Thorax uniformly yellowish brown, lateral margins brown. Legs: foreleg pale brown to translucent, midleg and hindleg translucent; length of segments in foreleg femur/ tibia/ tarsus (mm) viz., 0.5/ 0.7/ 0.6; length of tarsal segments (mm) viz., 0.03/ 0.3/ 0.11/ 0.1/ 0.06; Wing: C and Sc brown basally and washed brown distally, remainders translucent.

Abdomen: tergum pale yellow to translucent; sterna pale; cerci and median caudal filament translucent.

Mature nymph ( Figs 2 , 22–35 ) (in 95% ethanol). Body length (without cerci): 2.8–3.5 mm in male and female nymphs; cerci lengths 1.5 mm; median caudal filament 1.7 mm; width of head 1.4 mm; antennae length 1.2 mm. General body coloration brownish yellow.

Head ( Fig. 2 ) brownish yellow, eyes black, ocelli paler. Two long setae on anterior margin of clypeus and strongly protruded ( Fig. 2 ). Antennae yellowish transparent distally, absence of short setae at inner margin of pedicel. Epicranial suture paler. Labrum ( Fig. 22 ) length 1.7 mm; width 0.077 mm, emargination without setae, anterior margin with row of long setae, lateral margin with stout setae, dorsum of labrum with few long setae. Mandibles ( Fig. 23a, b ): rows of 4 and 8 long setae present below base of incisors; basal half of mandible chagrinated. Maxilla ( Fig. 24a, b ): galea with single stout spine and ventral base of lacinia with few bipectinate setae; maxillary palp two-segmented; segment II three times longer than segment I, half of segment II covered with setae. Hypopharynx ( Fig. 25 ): superlingua covered with stout setae and lingua with long setae at apical margin. Labium ( Fig. 26 ): glossae ovate with apical spines, paraglossae covered with thin setae, labial palp three-segmented, segment III longer than segments I and II, 2 transverse rows of stout setae at distal margin of segment III, segment I with eight stout setae on outer margin, basal outer margin of proximal segment and apical margin of middle segment of labial palp with two lanceolate setae.

Thorax: brownish yellow, lateral margins washed yellow. Legs evenly covered with scales, pale yellow with washed–brown, femora with ovoid large macula without scales and setae. Foreleg ( Fig. 27 ): length of femur/ tibia/ tarsus/ claw viz., 0.37/ 0.41/ 0.39/ 0.14 mm. Coxa with few spines on surface of outer margin and pair of long, thin spines on inner margin. Trochanter with two rows of stout spines on outer margin. Femur with 4 long, stout setae at middle of inner margin and dorsal surface with transverse row of lanceolate setae for 2/3 length, with few monopectinate, stout setae and long setae with feathered cap on outer margins. Tibia with two rows of long, filtering setae on lateral margin and one row on ventral margin. Tarsus with row of monopectinate setae on ventral margin and transverse row of long setae on lateral margin. Claw hooked with 5 denticles. Midleg ( Fig. 28 ): length of femur/ tibia/ tarsus/ claw viz., 0.33/ 0.24/ 0.17/ 0.10 mm. Coxa and trochanter same as foreleg. Femur with few long and short stout spines at outer margin, inner margin with row of stout spines and thin hair-like setae. Tibia with row of long and short stout spines on ventral margin. Tarsus with few long, hair-like setae. Claw long, slender and slightly curved with 4 denticles. Hindleg ( Fig. 29 ): length of femur/ tibia/ tarsus/ claw viz., 0.44/ 0.24/ 0.23/ 0.11 mm. Coxa, trochanter similar to those of foreleg. Femur with long spines and hair-like setae on inner and outer margins. Tibia with row of long and short stout spines on inner margin, surface with row of lanceolate setae. Tarsus with few long hair-like seate on surface, inner margin with stout spines, lateral margin with row of lanceolate setae. Claw slender and slightly curved with 6 denticles.

A bdomen: posterior margins of terga brown, remainders washed yellow. Tergum II ( Fig. 34 ) with medial projection upright, slightly curved backwards, lateral margin of tergum with spines and surface with scales, medial projection pale brown with scales and without spines. Lateral margin of tergum VII ( Fig. 35 ) with short bipectinate setae; dorsomedial margins of terga VII–IX with crowded scales. Sternum pale yellow. Gills ( Figs. 30–32 ): gill I pointed, two segmented, apex of segment I pulvinate; segment II 2.5 times longer than segment I. Gill covers ( Fig. 33 ) pale brown, evenly covered with scales, inner margins each with row of spines, outer margins each with small ridges (lanceolate like). Gills III–VI approximately triangular shaped with fringed bifid fimbriae; gill III with 12 bifurcated and 2 trifurcated fimbriae, and 17 lanceolate setae on margins; gill VI with 8 bifurcated fimbriae and 19 lanceolate setae on ventral margin and lack of trifurcated fimbriae. Caudal filaments translucent.

Egg ( Figs. 21 ) (dissected from female imago) oval shaped. Chorion with single thread running from polar region.

Etymology. The species is named after the goddess Sharadhambal, whose temple is in Sringeri (Chikkamagalore district, Karnataka), where the new species was collected.

Habitat. Nymphs of this species were found on the undersides of cobbles and pebbles in medium to fast current streams and associated with Ephemera sp. ( Ephemeridae ), Choroterpes sp. ( Leptophlebiidae ), Isonychia sp. ( Isonychiidae ), Rhoenanthus tungaiensis (Potamanthidae) and Baetis sp. ( Baetidae ), possibly feeding on fine particulate organic matter available in the water current and also in the substratum.

Distribution. Central Western Ghats, Karnataka ( India).

Figures

FIGURES 1–2. Mature nymph, dorsal view. 1–Head of Clypeocaenis gayathri sp. nov., 2–Head of Clypeocaenis sharadhae sp. nov.

FIGURES 17–21. Imago, Clypeocaenis sharadhae sp. nov. 17–Forewing, 18–Foreleg, 19–Genitalia, 20–Forceps, 21–SEM image of egg.

FIGURES 22–26. Mature nymph, Clypeocaenis sharadhae sp. nov., dorsal views. 22–Labrum, 23a, b–Mandibles, 24a, b– Maxillae, 25–Hypopharynx, 26–Labium.

FIGURES 27–35. Mature nymph, Clypeocaenis sharadhae sp. nov., dorsal view. 27–Foreleg, 28–Midleg, 29–Hindleg, 30– Gill I, 31–Gill III, 32–Gill VI, 33–Gill cover, 34–Tergum II, 35–Tergum VII.