Platybaetis uenoi Müller-Liebenau, 1980

Platybaetis uenoi Müller-Liebenau, 1980 View in CoL

( Figs 8–14 View FIGURE 8 View FIGURE 9 View FIGURE 10 View FIGURE 11 View FIGURE 12 View FIGURE 13 View FIGURE 14 , 15B View FIGURE 15 , 16 View FIGURE 16 )

Material examined: (1 larva on slide); 12 larvae, India, Nagaland, Peren district, Teipuki River near Poilwa village , 25.54165°N, 93.80529°E, 770 m, 19.VIII.2022, coll. T. Kubendran, Reg. no. I/E/840 GoogleMaps ; 5 larvae (1 larva on slide), India, Longleng district, Dikhu tributary River , 26.78654°N, 94.78654°E, 223 m, 23.VIII.2022, coll. T. Kubendran, Reg. no. I/E/841 GoogleMaps .

Description. larva ( Figs 8A, D View FIGURE 8 ; 9A–B View FIGURE 9 ): male: body length 7.4–7.5 mm; female: body length 8.4–8.5 mm. Cerci 6.0– 6.2 mm, median caudal filament five segments ( Figs 8E View FIGURE 8 , 9C View FIGURE 9 , 14E–F View FIGURE 14 ); antennae 1.2–1.4 mm ( Fig. 8F View FIGURE 8 ).

Head: Flattened, slightly wider than long; brownish yellow with diffusing irregular black and pale markings, well visible; frons and vertex with dark brown pattern; male turbinate eye reddish ( Fig. 9B View FIGURE 9 ). Antennae brown with ecru, scape thick with small setae on anterior margin, base broader, pedicel cylindrical, and flagellum brown with ecru markings, slightly shorter than head width, small hair-like setae on each segment ( Figs 8A, F View FIGURE 8 ). Posterior margin of head with incision ( Figs 8A–B, D View FIGURE 8 ). Labrum ( Figs 10A–C View FIGURE 10 ) rounded, 2.0× wider than long; distal margin with row of apically hair-like setae and feathered setae, dorsal surface with hair-like setae; arc of 1+4 stout medium setae ( Fig. 10B View FIGURE 10 ). Distal margin with medial emargination with blunt crenation ( Fig. 10C View FIGURE 10 ). Hypopharynx ( Fig. 10D View FIGURE 10 ) with long, thin setae and well-developed lingua and superlingua. Right mandible ( Fig. 11A View FIGURE 11 ) incisors with 6–7 denticles, prostheca slender, apex of mola with reduced tuft of setae. Left mandible ( Figs 11B–C View FIGURE 11 ) incisors with 6–7 denticles; prostheca comb-shaped; mola with thumb-like long apical extension. Basal half with 6–7 short simple setae scattered over dorsal surface. Maxillae ( Figs 11D–F View FIGURE 11 ) with 3 dentisetae and 3 canines; setae of inner dorsal row 1.3x longer than setae of inner ventral row; palps 2-segmented; segment II longer than segment I, inner margin slightly curved and outer margin almost straight, with small rounded well-visible projection at apex surrounding with simple setae. Labium ( Figs 10E–G View FIGURE 10 ) with glossae longer than paraglossae; glossae with long triangular setae at apex; a few small stout setae on dorsal margin; 7–8 long, stout setae on inner margin and a long, stout seta in middle; paraglossae broad with 3 rows of long, stout setae apically; dorsal surface with long, stout setae; palps 3-segmented, segment I broad with several micropores on dorsal surface ( Fig. 10G View FIGURE 10 ); segment II square, outer margin with short, fine, simple setae; dorsally with several micropores; ventrally with two medium, simple stout setae. Segment III slightly rounded with several short, stout acute setae ( Fig. 10E View FIGURE 10 ).

Thorax: Yellowish brown ( Figs 8A–B View FIGURE 8 ). Pronotum almost as broad as head capsule ( Figs 8A–B View FIGURE 8 ); pronotum posterolateral margin slightly rounded. Ventral side of the pronotum and mesonotum with small medial suture ( Fig. 8C View FIGURE 8 ). Hindwing pads absent. Legs generally yellow with a brown pattern ( Figs 12A–C View FIGURE 12 ; 13A–D View FIGURE 13 ). Foreleg ( Figs 12A View FIGURE 12 , 13A View FIGURE 13 ): femur apex slightly rounded, dorsal surface with small, stout scattered setae, outer margin with a row of long feathered and ciliate setae ( Fig. 12F View FIGURE 12 ), inner margin with small, stout scattered setae ( Fig. 12D View FIGURE 12 ); tibia 0.7x femur length, dorsal margin with row of long, hair like setae and few short stout setae ( Fig. 13A View FIGURE 13 ), patella tibial suture present along with long hair-like setae; tarsus 2.2x shorter than tibia, with dorsal row of simple setae, inner margin with a row of short, stout setae ending with fine, long seta near apex, claw with a single row of 8–9 denticles increasing in size towards apex, with few apical stripes, subapical setae absent ( Fig. 13E View FIGURE 13 ). Middle and hind legs as forelegs ( Figs 12B–C View FIGURE 12 , 13B–C View FIGURE 13 ).

Abdomen: Coloration of terga generally brown with yellowish pattern ( Figs 8A, D View FIGURE 8 , 9A–B View FIGURE 9 ); terga I–IV brown with yellow pattern, medially with four black spots; tergum V pale yellow with brown marks laterally; VI–VII dark brown with “T”-shaped pale yellowish marking; VIII pale yellow with medially black spots; IX–X brown; posterior margin of terga I–X with both blunt and sharp spines ( Figs 14A–C View FIGURE 14 ). Sterna I–X ecru mixed with yellow. Gills present on segments I–VII, simple, leaf-like, and rather broad; tracheae brown on gills II–VI, tracheae on gills I and VII not clearly marked, margin with minute setae ( Figs 14G–N View FIGURE 14 ). Paraproct distally slightly expanded, without marginal spines, surface covered with small rounded scale bases, fine simple setae, and small micropores ( Fig. 14D View FIGURE 14 ). Posterolateral extension (cercotractor) with small spines. Cerci shorter than body length; paracercus composed of only 5 segments ( Figs 8E View FIGURE 8 , 9C View FIGURE 9 , 14E–F View FIGURE 14 ).

Imago: Unknown.

Distribution: Nagaland ( India) ( Figs 15B View FIGURE 15 ).

Diagnosis: Platybaetis uenoi is distinguished by the following characters: (i) posterior margin of abdominal segments I–X with both acute and blunt denticles ( Figs 14A–C View FIGURE 14 ); (ii) gills on segments I–VII; tracheae well marked on II–VI; indistinct on I and VII ( Figs 14G–N View FIGURE 14 ); (iii) claw with 8–9 denticles; apical denticle larger than others and presence of strips ( Fig. 13E View FIGURE 13 ); (iv) paracercus composed of five segments, each with large hair-like setae alongside ( Figs 14E–F View FIGURE 14 ); (v) hindwing pads absent; (vi) labrum rounded with arc of 1+4 small blunt setae and medial emargination with blunt crenation ( Figs 10A–C View FIGURE 10 ); (vii) glossae with long triangular setae at apex ( Figs 9D View FIGURE 9 , 10F View FIGURE 10 ).

Ecology: Larvae of P. uenoi occur in the river Tepuiki ( Fig. 15B View FIGURE 15 ), which are the only tributaries of the Barak River in the state of Nagaland. The nearest human habitations are the Poilwa village, 4–5 km from the type locality. Poilwa is situated in the hilly tract of the Peren district in Nagaland and is inhabited by the Zeliang-Naga Tribe. The Tepuiki River has diverse aquatic resources. The villagers of Poilwa are conserving the river by prohibiting fishing gear and other destructive elements. In the river, remarkable numbers of aquatic insects were collected, especially Ephemeroptera ( Vietnamellidae , Heptageniidae , Ephemerellidae , and Baetidae ), Plecoptera ( Perlidae and Peltoperlidae ), fishes, Mollusca, etc. The environmental parameters are as follows: air temperature: 26.6°C, water temperature: 21.8°C, humidity: 69%, pH: 6.68, canopy: open, substrate index of the river: gravel: 10%; cobbles: 10%; boulders: 40%; bedrock: 30%; fine sand: 5%; and silt: 5%.