Platybaetis selvai Kubendran, Vasanth & Subramanian 2021

Platybaetis selvai Kubendran, Vasanth & Subramanian, 2021 Platybaetis selvai Kubendran, Vasanth & Subramanian, 2021: 576 (nymph). Type: nymphs, from India (Arunachal Pradesh). Materials examined: 25 nymphs, 1 male imago and 1 female imago (reared from mature nymphs), nearby 80 k milestone of Motuo Highway, Motuo county, Xizang, China, 29.616159°N, 95.477556°E, alt. 1464 m, 09.VII. 2023, leg. De-Wen Gong and Xu-Hong-Yi Zheng. Description Male imago (in alcohol). Body length 7.6 mm, forewing 8.0 mm, cerci 20.5 mm (Figs 1A, B). Head. Light yellowish (Figs 1A, B). Scape and pedicel pale, basal half of flagella light brown, other part whitish (Fig. 1B). Upper portion of compound eyes orange, turbinate, progressively larger from base to apex; lower portion of eyes black, semi-spherical; a narrow space (narrower than median ocellus) between two compound eyes (Figs 1A, B). Thorax. Pronotum pale, mesonotum yellowish-brown with brown stripes and dots along lateral margins, three oval deep brown dots at middle (Fig. 1B); a dark brown dot between base of midleg and hindleg on pleura (Figs 1A, 2A). Length ratio of forefemur: tibia: tarsus 1.0: 1.9: 1.6 (Fig. 2A); length ratio of segments of foretarsus 1.0: 8.2: 7.4: 4.4: 2.8 (Fig. 2C); forefemur with light brown markings; tibia and tarsus whitish (Fig. 2A). Two claws of foreleg one acute, one blunt (Fig. 2I). Surface of the tarsus and tibia with scales and scattered microtrichia (Fig. 2I). Length ratio of midfemur: tibia: tarsus 2.1: 3.4: 1.0 (Fig. 2A); segments of midtarsus 1.8: 1.0: 3.0 (Fig. 2D). Midfemur and tibia whitish, third segment of tarsus light brown, with one pointed claw and one blunt claw (Fig. 2A). Surface of the tarsus and tibia with scales and scattered microtrichia. Length ratio of hindfemur: tibia: tarsus 2.4: 3.8: 1.0 (Fig. 2A); segments of hindtarsus 1.4: 1.0: 2.7. Hindlegs similar to middle legs in color.Almost all veins of forewing pale except several crossveins, but base of longitudinal veins and nearby area of wings tinted with deep brown pigments (Fig. 1A). MA 2 connected to MA 1 with a crossvein, MA 2 connected to MP 1 with a crossvein; two long intercalaries between CuA and CuP; Sc vein and Rs vein with bullae (Figs 2G, 3B). Five crossveins between C and Sc (three in stigmatic area), two between Sc and R 1 (Figs 2G, 3B). Abdomen. Terga whitish, but terga V–VIII slightly deeper than others, yellowish (Figs 1A, B). Cerci pale (Fig. 2K); terminal filament with 2–3 segments (Fig. 2K). Genitalia: styliger pedicel distinctly wider than forceps, apicomesal margin with a dentation, two projections besides it slightly elongated (Figs 2K, 3C). Forceps with three segments but separating line between segment I and II indistinct; segment I about half segment II in length, segment III ca. half of segment I (Figs 2K, 3C). Segment II with a narrowed basal half, length ca. 1.5X length of segment I, length of segment III ca. 1.5X its width (Figs 2K, 3C). Subgenital plate between two styliger pedicel slightly convex posteriorly (Figs 2K, 3C). Female imago (in alcohol). Body 8.0 mm; forewing 10.0 mm, cerci missing, terminal filament 2–3 segments (Figs 1C, D). Similar to male but browner: vertex, pronotum, all femora and tarsi yellowish brown, all veins of forewings clear, much more distinct than male (Figs 1C, D). Head. Pale brown; compound eyes black; antennae with yellowish brown pedicel and basal half flagella, other part pale (Fig. 1D). Thorax. Coloration nearly the same as male imago, but with more diffuse brown markings (Fig. 1D). Veins of forewings are the same as male imago, with the coloration of veins darker (Figs 1C, D, 2G). Length ratio of forefemur: tibia: tarsus 1.3: 2.1:1.0 (Fig. 2B); segments of foretarsus 1.0: 4.0: 4.8: 2.7: 12.5 (Fig. 2E); Length ratio of midfemur: tibia: tarsus 2.8: 3.4: 1.0 (Fig. 2B); segments of midtarsus 1.4: 1.0: 2.5 (Fig. 2F); Length ratio of hindfemur: tibia: tarsus 2.5: 3.8: 1.0 (Fig. 2B); segments of hindtarsus 1.3: 1.0: 3.2. All legs with two claws, one acute and one blunt. Abdomen. Coloration similar to nymph: each terga and sterna with two pairs of grey to brown dots: the anterior pair slightly longer and more oblique than posterior pair, the latter pair dot-like (Figs 1D, 2H); lateral margins and nearby area of tergites and sternites gray to brown, segment III–IV and VI–VII slightly darker than others (Fig. 1C). All posterior margins of the sterna were almost straight except sternum VII, which extended posteriorly to a semi-circular plate (Figs 2H, J). Latero-posterior angles of tergum slightly extended (Fig. 1D). Nymph (see Kubendran et al. 2021). Diagnosis The nymphal diagnoses have been presented by Kubendran et al. (2021). The main points include: (1) relatively larger body than others (7.4–9.8 mm) (Figs 4A, B); (2) terminal filament (paracercus) with 10–11 segments (Figs 5J, K); (3) posterior margins of tergites with U-shaped or square denticles; (4) gills with very sparse setae on margins, outer and inner margins sclerotized, and tracheae with dark pigments except very base (Figs 5A–H). (5) Paraproct without marginal spines (Fig. 5I). Male imago is recognizable because of: (1) wings with pigmented base and veins (Fig. 1A); (2) grey femora and tarsi (Fig. 2A); (3) pale abdomen (Figs 1A, B); (4) convex subgenital plate (Figs 2K, 3C). Female imago has: (1) grey abdomen with two pairs of brown dots on each tergite and sternite (Figs 1D, 2H); (2) sternum VII extended into lobe (Figs 2H, J); (3) sternum IX with straight posterior margin (Figs 2H, J). Comparison The nymphs of Platybaetis selvai have the longer terminal filament (paracercus, 10–11 segments) than most species in the same genus (Figs 5J, K) (Kubendran et al. 2021; Sutthinun et al. 2018). The nymphs of P. probus Müller-Liebenau, 1984 have 9-segmented visible paracercus. If we consider the base of it, the terminal filaments of those two species may be similar in shape or length. The latter species distributes in Malaysia. The male imago of this species has pale abdomen (Figs 1A, B). The other known males of four species have distinct color (usually regular orange markings) on abdomen (Kluge& Novikova 2011; Sutthinun et al. 2018). In addition, unlike P. mamasae and P. wallacei (Kluge& Novikova 2011), the wings of P. selvai have brown pigments at base (Fig. 2G), which are also found in the species P. bishopi and P. nayokensis (Sutthinun et al. 2018). The veins of P. selvai are darker than P. nayokensis but paler than P. bishopi (Figs 1A, B). Like the male, the female imago of P. selvai is paler than others too (Figs 1C, D). It has four dots on each tergite and sternite (Figs 1D, 2H) but the other species have colorful markings on abdomen (Sutthinun et al. 2018). The straight posterior margin of sternum IX (Figs 2H, J) is also unique in the genus because all other known females have concave margin of sternum IX. Moreover, the sternum VII of this species Platybaetis selvai (Figs 2H, J) seems longer than others but these characters of others were not mentioned clearly before. The main differences of five Platybaetis males are presented in the table 1.