Clypeocaenis kaveri Balasubramanian and Muthukatturaja, 2021

Balasubramanian, Chelliah & Muthukatturaja, Marimuthu, 2021, Two additional new species of Clypeocaenis Soldán, 1978 (Ephemeroptera Caenidae) from the Western Ghats of Peninsular India, Zootaxa 4915 (3), pp. 377-388 : 378-383

Clypeocaenis kaveri Balasubramanian and Muthukatturaja , sp. nov.

(Figs. 1, 5–18)

Materials examined. Holotype (in ethanol): male imago [ZSI/SRC-I/E 493], India, river Kaveri, Napoklu, Kodagu district , Karnataka state, 19-V- 2019, 872 m (12.3140985 °N, 75.6983046 °E), collected by Balasubramanian & Muthukatturaja. Paratypes (in ethanol): 3 female imagoes [ZSI/SRC-I/E 494] and 3 mature nymphs [ZSI/SRC-I/E 495], same data as holotype, deposited in Zoological Survey of India, Southern Regional Centre, Chennai .

Description. Mature Nymph (preserved in 90% ethanol) Dimensions (mm): body length (excluding cerci), 3.5; cerci length, 2.1; median caudal filament, 2.5; width of head, 0.4; antennae length, 1.2. General body coloration washed yellow dorsally and pale yellow ventrally, young specimens generally paler; legs pale yellow.

Head (Fig. 1): length, 0.35 mm, pale yellow; eyes black; ocelli with apical half white, basal half black; antennae yellow transparent distally; pedicel with 4 setae; epicranial suture paler; two long setae with hairs on posterior margin of clypeal protrusion. Labrum (Fig. 5): emargination without setae, anterior margin with row of long setae and few short thin setae, dorsum of labrum with row of long thin setae near mesal margin. Outer incisors of mandibles (Fig. 6a, b) five-forked; 7 long thin setae present below molar; 1/2 of basal part of mandible with dense scales. Maxillary palp (Fig. 7) two segmented with protuberance, segment II two times longer than segment I, apical 1/2 of segment II covered with long thin setae; outer margin of segment I with row of 5 stout setae and inner margin with 2 setae; galea with prominent thick denticle and few thin spines; ventral base of galea-lacinia with row of few thin setae; apex of galea-lacinia with clump of hair like long setae. Hypopharynx (Fig. 8): apical margin of sub lingua covered with hair like setae and lingua with very short spines at apical margin. Labium (Fig. 9): glossae rounded, paraglossae covered with thin setae, three segmented labial palp, segment III much longer than segments I & II, two rows of stout spine at inner margin of segment III, segment I with row of 7 stout spines at outer margin.

Thorax: Pronotum pale yellow, margins pale brown; anterolaterally produced. Mesonotum pale yellow with black smudges between wing pads. Legs: evenly covered with scales, pale yellow. Foreleg (Fig. 10): length ratio of femora; tibia; tarsi; claw viz., 0.45/ 0.4/ 0.35/ 0.11. Coxa with few thin setae on surface; trochanter with row of setae at outer margin; femur with 4 long spines at middle of inner margin and row of bifid spines at outer margin and subapical surface; tibia with four rows of filtering setae, two rows on lateral and ventral margins, inner margin with row of stout spines and 9 long thin setae; inner margin of tarsi with row of stout spines and row of long thin setae on lateral margin; claw hooked with 6 denticles. Midleg (Fig. 11): length ratio of femora; tibia; tarsi; claw viz., 0.4/ 0.3/ 0.25/ 0.11. Coxa and trochanter similar to foreleg except row of setae at outer margin; dorsal surface of femur with sparse bifid spines and few bifid spines at ½ of outer margin; inner margin of tibia with row of bifid and stout spines; tarsi with row of monopectinate setae on inner margin; claw long, slender and hooked with 8 denticles. Hindleg (Fig. 12): length of femora; tibia; tarsi; claw viz.,.06/ 0.45/ 0.4/ 0.15 mm. Coxa and trochanter similar to midleg; outer margin of femur with few long and stout bifid spines; tibia with row of few bifid spines at inner and outer margins; inner margin with row of stout spines and row of few bipectinate spines at mesal margin; inner margin of tarsi with row of monopectinate spines; claw hooked with 8 denticles.

Abdomen: pale yellow; tergum II (Fig. 17) with upright and backwardly curved, long, medial projection; terga VI–IX with blunt postero lateral projections; tergum VII (Fig. 18) with bifid spines on posterior margin; terga with small scales on surface. Sterna whitish yellow. Gills (Fig. 13–16): gill I bluntly pointed with segment I broadened apically and segment II five times longer than segment I; tracheated gill cover (Fig. 14) pale yellow, evenly covered with scales and inner margin with row of thin setae, posterior margin with small bifid spines; gill III–VI triangular and lamellate; gill III with fringed trifid fimbiriae at apex, outer margin with row of bifid fimbiriae, surface of lamella with sparse lanceolate setae; gill VI with 8 bifid fimbiriae and few lanceolate setae on inner and outer margin of lamella. Cerci translucent; whorls of setae on each segment.

Male imago (Figs. 3, 19–21) (in alcohol). Dimensions (in mm): body length, 2.3; cerci length, 5.2; median caudal filament, 5.8; length of antenna, 0.4; length of forewing, 3.9; width of forewing, 1.6.

Head (Fig. 3) brownish yellow, length 0.3 mm, width 0.6 mm; anterior margin and area around antennal base pale brown; scape and pedicel of antennae yellowish brown, flagellum pale yellow; dorsal diameter of eye 0.085 mm; distance between compound eyes 0.3 mm; eyes black; ocelli with apical half white, basal half black.

Thorax uniformly yellowish brown, lateral margins brown. Legs translucent; length ratio of segments in foreleg (Fig. 20) femur/ tibia/ tarsus (mm) viz., 0.4/ 0.55/ 0.33; length ratio of tarsal segments viz., 0.04/ 0.13/ 0.06/ 0.06/ 0.04. Wing: Forewings (Fig. 19) oval, with few cross veins arranged singly except proximal half of R; C and Sc brown, remainders translucent; base of R 4+5 not connected with R; absence of fork at CuP; vein MP forked at 1/3 distance from base to margin; absence of cross vein at anal region.

Abdomen: tergum translucent; terga VII–IX pale; sterna pale. Genitalia (Fig. 21) pale, forceps 0.01 mm, penis 0.13 mm; penis lobes completely fused and not produced laterally; absence of short bristles on posterior margin of penis lobe; forceps each composed of one segment with small bristles on surface; forceps smaller than penis lobe; cerci and median caudal filament translucent.

Female imago (in alcohol). Dimensions (in mm): body length, 3.4; cerci length, 3.8; median caudal filament, 4.0; length of antenna, 0.32; length of forewing, 3.6; width of forewing, 1.8.

Head brownish yellow, length 0.2 mm, width 0.5 mm; anterior margin and area around antennal base pale brown to yellow; scape and pedicel of antennae pale brown, flagellum translucent; distance between compound eyes 0.4 mm; dorsal diameter of eye 0.1 mm; eyes black; ocelli with apical half white, basal half black.

Thorax yellowish brown, lateral margins brown. Legs: foreleg pale brown to translucent, midleg and hindleg translucent; length ratio of segments in foreleg femur/ tibia/ tarsus (mm) viz., 0.4/ 0.6/ 0.3; length of tarsal segments (mm) viz., 0.03/ 0.12/ 0.06/ 0.05/ 0.04. Wing: C and Sc brown; remainders translucent; other details as in male imago.

Abdomen: tergum pale yellow to translucent; terga II–IX with brown markings medially; sterna pale; cerci and median caudal filament translucent.

Diagnoses. Nymph: (i) fore femur with 4 long spines at middle of inner margin and row of bifid spines on outer margin; (ii) dorsal surface of mid femur with sparse bifid spines and few bifid spines at ½ of outer margin; inner margin of tibia with row of bifid and stout spines; (iii) outer margin of hind femur with few long and stout bifid spines; tibia with row of few bifid spines on inner and outer margins; (iv) posterior margins of gill covers with small bifid spines; (v) gill III with fringed trifid fimbiriae at apex, outer margin with row of bifid fimbiriae, surface of lamella with sparse lanceolate setae.

Imago, male: (i) base of R 4+5 not connected with R; (ii) vein MP forked at 1/3 distance from base to margin; (iii) absence of cross vein in anal region; (iv) forceps smaller than penis lobe.

The new species of C. kaveri sp. nov. is closely related to C. gayathri ; each have a slightly protruded clypeus. However, the nymph of Clypeocaenis kaveri sp. nov. can be distinguished from C. gayathri by the following combination of characters: (i) pedicel thrice as long as scape; (ii) segment I of labial palp with 7 stout spines at outer margin; (iii) presence of four longer setae on ventral margin of fore femur and outer margin with row of bifid spines; (iv) tibiae of middle and hind legs each with row of bifid spines at inner margin; (v) 9 short bifid bristles on the ridge near anterior margin of gill cover; (vi) gill VI with 8 bifurcated fimbiriae; and (vii) claws with 6–9 denticles.

Etymology. The species name kaveri refers to the river name, Kaveri, Kodagu district, Karnataka, where the new species was collected.