Platybaetis selvai Kubendran, Vasanth & Subramanian, 2021

Wang, Ning-Ning, Sun, Yu-Xian & Zhou, Chang-Fa, 2024, The imagines of Platybaetis selvai Kubendran et al., 2021 (Ephemeroptera: Baetidae) from China, Zootaxa 5523 (3), pp. 373-380 : 374-377

publication ID	https://doi.org/ 10.11646/zootaxa.5523.3.5
publication LSID	lsid:zoobank.org:pub:B16F888E-7CB0-4D30-A9BB-7213800A4EEE
DOI	https://doi.org/10.5281/zenodo.13971746
persistent identifier	https://treatment.plazi.org/id/62047F34-EB1E-FF94-FF00-6AE1FBA4F98A
treatment provided by	Plazi
scientific name	Platybaetis selvai Kubendran, Vasanth & Subramanian, 2021
status

Treatment

Platybaetis selvai Kubendran, Vasanth & Subramanian, 2021: 576 View Cited Treatment (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 GoogleMaps .

Description

Male imago (in alcohol). Body length 7.6 mm, forewing 8.0 mm, cerci 20.5 mm ( Figs 1A, B View FIGURE 1 ).

Head. Light yellowish ( Figs 1A, B View FIGURE 1 ). Scape and pedicel pale, basal half of flagella light brown, other part whitish ( Fig. 1B View FIGURE 1 ). 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 View FIGURE 1 ). Thorax. Pronotum pale, mesonotum yellowish-brown with brown stripes and dots along lateral margins, three oval deep brown dots at middle ( Fig. 1B View FIGURE 1 ); a dark brown dot between base of midleg and hindleg on pleura ( Figs 1A View FIGURE 1 , 2A View FIGURE 2 ). Length ratio of forefemur: tibia: tarsus 1.0: 1.9: 1.6 ( Fig. 2A View FIGURE 2 ); length ratio of segments of foretarsus 1.0: 8.2: 7.4: 4.4: 2.8 ( Fig. 2C View FIGURE 2 ); forefemur with light brown markings; tibia and tarsus whitish ( Fig. 2A View FIGURE 2 ). Two claws of foreleg one acute, one blunt ( Fig. 2I View FIGURE 2 ). Surface of the tarsus and tibia with scales and scattered microtrichia ( Fig. 2I View FIGURE 2 ). Length ratio of midfemur: tibia: tarsus 2.1: 3.4: 1.0 ( Fig. 2A View FIGURE 2 ); segments of midtarsus 1.8: 1.0: 3.0 ( Fig. 2D View FIGURE 2 ). Midfemur and tibia whitish, third segment of tarsus light brown, with one pointed claw and one blunt claw ( Fig. 2A View FIGURE 2 ). 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 View FIGURE 2 ); 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 View FIGURE 1 ). 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 View FIGURE 2 , 3B View FIGURE 3 ). Five crossveins between C and Sc (three in stigmatic area), two between Sc and R 1 ( Figs 2G View FIGURE 2 , 3B View FIGURE 3 ). Abdomen. Terga whitish, but terga V–VIII slightly deeper than others, yellowish ( Figs 1A, B View FIGURE 1 ). Cerci pale ( Fig. 2K View FIGURE 2 ); terminal filament with 2–3 segments ( Fig. 2K View FIGURE 2 ). Genitalia: styliger pedicel distinctly wider than forceps, apicomesal margin with a dentation, two projections besides it slightly elongated ( Figs 2K View FIGURE 2 , 3C View FIGURE 3 ). 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 View FIGURE 2 , 3C View FIGURE 3 ). 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 View FIGURE 2 , 3C View FIGURE 3 ). Subgenital plate between two styliger pedicel slightly convex posteriorly ( Figs 2K View FIGURE 2 , 3C View FIGURE 3 ).

Female imago (in alcohol). Body 8.0 mm; forewing 10.0 mm, cerci missing, terminal filament 2–3 segments ( Figs 1C, D View FIGURE 1 ). 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 View FIGURE 1 ). Head. Pale brown; compound eyes black; antennae with yellowish brown pedicel and basal half flagella, other part pale ( Fig. 1D View FIGURE 1 ). Thorax. Coloration nearly the same as male imago, but with more diffuse brown markings ( Fig. 1D View FIGURE 1 ). Veins of forewings are the same as male imago, with the coloration of veins darker ( Figs 1C, D View FIGURE 1 , 2G View FIGURE 2 ). Length ratio of forefemur: tibia: tarsus 1.3: 2.1:1.0 ( Fig. 2B View FIGURE 2 ); segments of foretarsus 1.0: 4.0: 4.8: 2.7: 12.5 ( Fig. 2E View FIGURE 2 ); Length ratio of midfemur: tibia: tarsus 2.8: 3.4: 1.0 ( Fig. 2B View FIGURE 2 ); segments of midtarsus 1.4: 1.0: 2.5 ( Fig. 2F View FIGURE 2 ); Length ratio of hindfemur: tibia: tarsus 2.5: 3.8: 1.0 ( Fig. 2B View FIGURE 2 ); 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 View FIGURE 1 , 2H View FIGURE 2 ); lateral margins and nearby area of tergites and sternites gray to brown, segment III–IV and VI–VII slightly darker than others ( Fig. 1C View FIGURE 1 ). All posterior margins of the sterna were almost straight except sternum VII, which extended posteriorly to a semi-circular plate ( Figs 2H, J View FIGURE 2 ). Latero-posterior angles of tergum slightly extended ( Fig. 1D View FIGURE 1 ).

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 View FIGURE 4 ); (2) terminal filament (paracercus) with 10–11 segments ( Figs 5J, K View FIGURE 5 ); (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 View FIGURE 5 ). (5) Paraproct without marginal spines ( Fig. 5I View FIGURE 5 ).

Male imago is recognizable because of: (1) wings with pigmented base and veins ( Fig. 1A View FIGURE 1 ); (2) grey femora and tarsi ( Fig. 2A View FIGURE 2 ); (3) pale abdomen ( Figs 1A, B View FIGURE 1 ); (4) convex subgenital plate ( Figs 2K View FIGURE 2 , 3C View FIGURE 3 ).

Female imago has: (1) grey abdomen with two pairs of brown dots on each tergite and sternite ( Figs 1D View FIGURE 1 , 2H View FIGURE 2 ); (2) sternum VII extended into lobe ( Figs 2H, J View FIGURE 2 ); (3) sternum IX with straight posterior margin ( Figs 2H, J View FIGURE 2 ).

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 View FIGURE 5 ) ( 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 View FIGURE 1 ). 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 View FIGURE 2 ), 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 View FIGURE 1 ).

Like the male, the female imago of P. selvai is paler than others too ( Figs 1C, D View FIGURE 1 ). It has four dots on each tergite and sternite ( Figs 1D View FIGURE 1 , 2H View FIGURE 2 ) but the other species have colorful markings on abdomen ( Sutthinun et al. 2018). The straight posterior margin of sternum IX ( Figs 2H, J View FIGURE 2 ) 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 View FIGURE 2 ) seems longer than others but these characters of others were not mentioned clearly before.