Clypeocaenis napoklu 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 : 383-387

Clypeocaenis napoklu Balasubramanian and Muthukatturaja , sp. nov.

(Figs. 2, 22–35)

Materials examined. Holotype (in ethanol): male imago [ZSI/SRC-I/E 496], 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 497] and 3 mature nymphs [ZSI/SRC-I/E 498], 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), 3.1; cerci length, 1.3; median caudal filament, 1.7; width of head, 0.6; antennae length, 1.0. General body coloration washed yellowish brown dorsally and pale yellow ventrally.

Head (Fig. 2): length, 0.4, yellowish brown; eyes black; ocelli with apical half white, basal half black; antennae pale yellow; pedicel with 4 setae; epicranial suture paler; two long setae with hairs on posterior margin of clypeal protrusion. Labrum (Fig. 22): emargination without setae, anterior margin with row of long setae and few short thin setae, dorsum of labrum with few sparse long thin setae near anterior margin. Incisors of mandibles (Fig. 23a, b) triforked; 8 long thin setae present below molar; 1/2 of basal part of mandible with dense scales. Maxillary palp (Fig. 24) two segmented, 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 7 stout 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. 25): apical margin of sub lingua covered with hair like setae and lingua with very short spines at apical margin. Labium (Fig. 26): glossae rounded with numerous setae, paraglossae covered with thin setae, labial palpi three segmented, segment III longer than segments I & II, two rows of stout spine at inner margin and seven long stout spines projected towards anterior region of segment III, segment I with row of 7 bifid spines at outer margin; segment II with bifid spine at apex.

Thorax: Pronotum yellowish brown, margins brown; anterolaterally produced. Mesonotum pale yellow with black smudges between wing pads. Legs: evenly covered with scales; light bands on fore femur, tibia and tarsi; middle and hind legs pale yellow. Foreleg (Fig. 27): length ratio of femora; tibia; tarsi; claw viz., 0.4/ 0.3/ 0.3/ 0.1. Coxa with few thin setae on surface; trochanter with row of setae on outer margin; femur with 2 long spines at middle of inner margins and row of thin setae at outer margin, row of 5 small bifid spines on subapical surface; tibia with four rows of very long filtering setae, two rows on lateral and ventral margins, distal margin with few and row of long thin setae; inner margin of tarsi with row of monopectinate setae and row of long thin setae on lateral margin; claw long, slender, and hooked, with 5 denticles. Midleg (Fig. 28): length ratio of femora; tibia; tarsi; claw viz., 0.4/ 0.25/ 0.25/ 0.12. Coxa and trochanter similar to foreleg except row of setae on outer margin; inner and outer margins of femur with row of long thin setae; inner margin of tibia with row of stout spines and row of thin long setae; tarsi similar to tibia; claw slender, hooked, with 5 denticles. Hindleg (Fig. 29): length of femora; tibia; tarsi; claw viz.,.055/ 0.35/ 0.35/ 0.8. Coxa, trochanter and femur similar to midleg; inner margin of tibia with row of stout spines and row of thin long setae, row of bipectinate setae on mesal margin; tarsi similar to tibia except inner margin with long bipectinate spine; claw hooked, with 5 denticles.

Abdomen: yellowish brown; tergum II (Fig. 34) with upright, backwardly curved, short medial projection; terga IV–IX with postero lateral projections; terga VII–IX with postero lateral projections acute; tergum VII (Fig. 35) with small ridges at posterior margin; terga with small scales on surface. Sterna pale yellow. Gills (Fig. 30–33): segment I pulvinate; segment II of gill I pointed and four times longer than segment I; tracheated gill cover (Fig. 12) pale brown, evenly covered with scales and inner margin with row of thin setae, outer and posterior margin with row of bifid spines; gill III–VI triangular and lamellate; gill III with fringed four-forked fimbiriae at apex, outer margin with row of bifid fimbiriae, surface of lamella with sparse lanceolate setae; gill VI with fringed trifid fimbiriae at apex, outer margin with 8 bifid fimbiriae, surface of lamella with sparse lanceolate setae. Cerci pale yellow, whorls of setae on each segment.

Male imago (Figs. 4, 37–39) (in alcohol). Dimensions (in mm): body length, 2.1; cerci length, 6.3; median caudal filament, 6.7; length of antenna, 0.5; length of forewing, 3.4; width of forewing, 1.9.

Head (Fig. 4) brownish yellow, length 0.5 mm, width 0.5 mm; anterior margin and area around antennal base pale brown; scape and pedicel of antennae pale brown, flagellum pale yellow; dorsal diameter of eye 0.05 mm; distance between compound eyes 0.3 mm; eyes black; ocelli with apical half white, basal half black.

Thorax yellowish brown, lateral margins brown. Legs translucent; length ratio of segments in foreleg (Fig. 37) femur/ tibia/ tarsus viz., 0.3/ 0.6/ 0.38; length ratio of tarsal segments viz., 0.04/ 0.17/ 0.07/ 0.06/ 0.04. Wing: Forewings (Fig. 36) oval, with few cross veins arranged singly; two cross veins at proximal half of R; C and Sc brown, remainders translucent; vein MP forked at 1/3 distance from base to margin; CuP forked at ¼ distance from the base to margin; 2 cross vein in anal region.

Abdomen: terga translucent; terga VIII–IX pale; sterna pale. Genitalia (Fig. 38) pale, forceps 0.01 mm, penis 0.9 mm; penis lobes completely fused and not produced laterally; no short bristles on posterior margin of penis lobe; forceps (Fig. 39) composed of one segment with small bristles on surface and apex; forceps little longer than penis lobe; cerci and median caudal filament translucent.

Female imago (in alcohol). Dimensions (in mm): body length, 3.6; cerci length, 2.3; median caudal filament, 3.4; length of antenna, 0.05; length of forewing, 3.5; width of forewing, 1.9.

Head brown, 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 0.35 mm; dorsal diameter of eye 0.15 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 viz., 0.3/ 0.5/ 0.3; length of tarsal segments (mm) viz., 0.03/ 0.15/ 0.05/ 0.04/ 0.03; Wing: C and Sc brown; remainders translucent; other details as in male imago.

Abdomen: tergum pale yellow to translucent; terga III–VII with pale brown markings; terga VIII & IX translucent and posterior margin of tergum IX pale brown; sterna pale; cerci and median caudal filament translucent.

Diagnoses. Nymph: (i) light bands on fore femur, tibia and tarsi; (ii) fore femur with 2 long setae at middle of inner margin and a row of thin setae at outer margin, a row of 5 small bifid spines at subapical surface; (iii) hind tarsi with a long bipectinate spine; (iv) claws slender, hooked, with 5 denticles; (v) outer and posterior margins of gill covers with row of bifid spines; (vi) gill III with fringed four-forked fimbiriae at apex, outer margin with row of bifid fimbiriae.

Imago, male: (i) vein MP forked at 1/3 distance from base to margin; (ii) cross vein at anal region; (iii) forceps little longer than penis lobe.

Clypeocaenis napoklu sp. nov. is closely related to C. sharadhae ( Muthukatturaja et al., 2020) ; each have a strongly protruded clypeus. The nymph of C. napoklu sp. nov. can be distinguished from C. sharadhae , however, by the following combination of characters: (i) pedicel twice as long as scape; (ii) segment I of labial palp with 7 bifid spines at outer margin; (iii) fore femur with 2 long setae at middle of inner margin; (iv) fore femur, tibia and tarsi with light bands; (v) gill III with one tetra furcated and 12 bifurcated fimbriae; and (vi) claw with 5 denticles. The imago of C. napoklu sp. nov. can be distinguished from C. sharadhae by the following combination of characters: (vii) CuP forked at 1/3 distance from the base to margin; (viii) forceps slightly longer than penis lobes.

Etymology. The species name napoklu refers to the type locality, where the new species was collected.