Baetis (Tenuibaetis) reasiensis Vasanth, Kubendran, Subramanian & Gattolliat, 2025

Vasanth, M., Kubendran, T., Subramanian, K. A., Gattolliat, J-L. & Banerjee, Dhriti, 2025, Three new species of the subgenus Tenuibaetis Kang & Yang, 1994 (Ephemeroptera: Baetidae) from India, Zootaxa 5665 (3), pp. 374-396 : 385-391

publication ID	https://doi.org/10.11646/zootaxa.5665.3.4
publication LSID	lsid:zoobank.org:pub:1729896A-7BEB-4084-B455-9FC970B54A97
DOI	https://doi.org/10.5281/zenodo.16609429
persistent identifier	https://treatment.plazi.org/id/F77E8793-880C-FF85-FF2C-FA1AF493FB91
treatment provided by	Plazi
scientific name	Baetis (Tenuibaetis) reasiensis Vasanth, Kubendran, Subramanian & Gattolliat
status	sp. nov.

Treatment

Baetis (Tenuibaetis) reasiensis Vasanth, Kubendran, Subramanian & Gattolliat sp. nov.

( Figs 9–12 View FIGURE 9 View FIGURE 10 View FIGURE 11 View FIGURE 12 , 13 View FIGURE 13 )

Material examined: Holotype (ZSI) male mature larva, INDIA, Jammu & Kashmir, Reasi district , Chenab River, 33.072 11 N 74.834 46 E, Alt. 420 m. 18.XI.2018, Coll. T. Kubendran (Reg. No. I /E/879) . Paratypes. 7 larvae, same data as holotype (Reg. No. I /E/880) .

Mature larva ( Figs 9A–C View FIGURE 9 ). Body length: 3.4–3.7 mm; cerci length 2.0– 2.5 mm; paracercus length 1.3–1.5 mm. Antennae much longer than head capsule. Coloration ( Figs 9A–C View FIGURE 9 ): Head brown, medially with yellow pattern; clypeus pale with brown; pronotum, mesonotum brown with a yellow band distally; abdominal terga brown; except tergum IV yellow; terga V –VII posterior margin dark brown; IX–X yellow; cerci pale yellow; thorax ventrally pale yellow, legs pale yellow with brown; femur dorsally pale yellow and light brown apically; claws distally reddish brown and sternum pale brown except sterna IX–X yellow. Head. Antenna ( Fig. 12J View FIGURE 12 ): Scape and pedicel sub-cylindrical, flagellum long with thin small stout setae at apex of each segment. Labrum ( Figs 10A–B View FIGURE 10 ): Rounded with length 0.6× maximum width. Medial emargination of distal margin deep cleft, with apically pointed process. Dorsally with abundant medium, fine, simple setae dispersed from medial to basal area; submarginal arc of 1+7 simple setae. Ventral marginal row of setae composed with long, feathered setae laterally and anterolaterally, and long, bifid, pectinate setae medially; ventral surface with two short, spine-like setae near lateral and anterolateral margin. Hypopharynx ( Fig. 10C View FIGURE 10 ): Broad, lingua laterally rounded and as long as superlingua. Lingua longer than broad, distal half not expanded. Superlingua rectangular, lateral margin rounded with thin small setae along distal margin. Right mandible ( Fig. 10D View FIGURE 10 ): Incisors fused. Outer and inner incisors with 3+4 denticles respectively. Prostheca slender and distolaterally denticulate. Margin between prostheca and mola without setae or crenelation. Single seta at apex of mola present. Left mandible ( Fig. 10E View FIGURE 10 ): Incisors fused with distinct denticles. Outer and inner incisors with 4 and 3 denticles respectively. Prostheca robust, apically with small stout denticles and comb-shape structure. Margin between prostheca and mola almost straight. Tuft of two setae at apex of mola present. Both mandibles with lateral margin almost straight; basal half with fine, simple setae scattered over dorsal surface. Maxilla ( Figs 10F–G View FIGURE 10 ): Galea-lacinia with two simple setae under crown. Inner dorsal row of setae with three denti-setae, distal denti-seta tooth-like with small stout setae, middle denti-seta slender, trifid and pectinate, proximal denti-seta slender, trifid and pectinate furcation well developed and abducted. Medially with two feathered, spine-like seta and 5–6 long, simple setae. Maxillary palp 1.4× as long as length of galea-lacinia; two segmented. Palp segment II 1.3× length of segment I. Fine, simple setae, scattered over surface of segments I and II. Second half of segment II enlarged; apex almost rounded without nipple and without excavation at inner distolateral margin. Labium ( Figs 11A–C View FIGURE 11 ): Glossae shorter than paraglossae; inner margin of glossae with 9–10 long spine-like setae, apex with 4 long, robust, spatulate setae and a medium, robust seta; outer margin with 3 spine-like setae, base with simple setae. Paraglossae subrectangular slightly curved inward; apex rounded with three rows of long robust distally pectinate setae in apical area and few simple setae in antero-medial area. Dorsally with a row of long spine-like setae near inner margin.

Labial palp 3-segmented; segment I longer than segments II and III combined. Segment II slightly produced inward to form a moderately expanded lobe at distal corner; dorsally with a row of 5–6 fine medium simple setae; segment III conical with small tip at apex, slightly asymmetrical with a small concavity at inner apex; covered with short stout spine-like setae. Segments II and III with fine simple setae scattered over dorsal surface. Thorax. Hind wing pads ( Fig. 12H View FIGURE 12 ): Present. Foreleg ( Figs 11D–H View FIGURE 11 ): Ratio of foreleg segments (femur: tibia: tarsi: claw) 1:0.8:0.6:0.2. Femur length 2.7× maximum width. Dorsal margin with a row of 22–23 long, stout, apically rounded 2-channel setae; length of setae 0.16× maximum width of femur. Apex rounded with few minute setae. Lateral surface of femur with 5 stout setae. Villopore well developed. Dorsal margin of tibia with numerous spatulate 2-channel setae; lateral margin of tibia with row of numerous small stout and hair-like setae along patella-tibial suture. Dorsal margin of tarsus with a row of small, 2-channel setae in proximal half with hair-like setae; ventral margin with 7–9 stout spine-like setae increasing in length towards apex. Claw with a row of 12 denticles. Middle leg ( Fig. 12A–E View FIGURE 12 ): Dorsal margin with a row of 15–16 long, stout, apically rounded setae; length of setae 0.16× maximum width of femur. Dorsal margin of tibia with numerous stout spatulate setae. Lateral surface of tibia with stout setae, and spine-like setae along patella-tibial suture. Dorsal surface of tarsi with 5 stout setae; ventral margin with 9–10 stout setae, apex with one short, stout, spine-like seta. Hind leg ( Fig. 12F View FIGURE 12 ): Dorsal margin with a row of 12–13 long, stout, apically rounded setae; length of setae 0.14× maximum width of femur. Lateral surface of tibia 25–28 clavate setae and distally without setae. Dorsal margin of tarsi with 6–7 stout setae; lateral margin of tibia with numerous stout, spatulate setae and inner margin with spine-like stout setae. Dorsal surface of tibia with stout setae and spine-like setae. Abdomen. Terga ( Fig. 12K View FIGURE 12 ) surface with regular row of V-shaped scale bases and scattered fine, simple setae; distal margin with blunt, triangular spines. Gills ( Fig. 12G View FIGURE 12 ): Single lamellate gills present on segments I–VII. Margin with small denticles with intercalating fine, simple setae. Tracheation transparent and dorsal surface with micropore. Paraproct ( Fig. 12I View FIGURE 12 ): Distally not expanded, with 8–9 blunt marginal stout spines. Surface with scattered micropores and fine simple setae, with more round patches with small setae and patch of notched scales. Cercotractor with small, marginal spines.

Imago: Unknown.

Etymology: The specific epithet reasiensis is a Latinized adjective formed from the type locality.

Distribution: Jammu & Kashmir (North Western Himalaya), India ( Fig. 13 View FIGURE 13 ).

Diagnosis: Baetis (T.) reasiensis Vasanth, Kubendran, Subramanian & Gattolliat sp. nov. can be distinguished from all known species of the subgenus Tenuibaetis by the following combination of characters: (i) Antennae much longer than head capsule ( Fig. 9C View FIGURE 9 ); (ii) labrum with dorsal submarginal arc of 1+7 simple setae ( Figs 10A–B View FIGURE 10 ); (iii) right mandible with outer and inner incisors with 3+4 denticles ( Fig. 10D View FIGURE 10 ); (iv) maxillary palp slightly longer than galea-lacinia, segment II long, apically broad and rounded ( Figs 10F–G View FIGURE 10 ); (v) segment II of labial palp with a moderately expanded lobe distomedially ( Figs 11A–B View FIGURE 11 ); (vi) lateral surface of forefemur with 5 stout setae ( Fig. 11G View FIGURE 11 ); (vii) dorsal margin of forefemur with row of 22–23 long, stout, apically rounded 2-channel setae ( Fig. 11D View FIGURE 11 ); (viii) dorsal surface of all tibia with stout, clavate setae ( Figs 11F View FIGURE 11 , 12C View FIGURE 12 ); (ix) mesothorax with yellow band distally ( Fig. 9A View FIGURE 9 ); (x) claw with a row of 12 denticles ( Fig. 11H View FIGURE 11 ).

Ecology: The type locality of the new species is the Chenab River, Reasi district, Jammu & Kashmir. The riverbed composition is as follows: cobbles 40%, boulders 25%, fine sand 25% and slit 10%. The Chenab Riverine is 4–4.5 m wide and 35–45 cm depth and medium water current (0.5 m /sec.), temperature (atmosphere) 20.6°C, temperature (water) 17.5°C, humidity 56% and pH 6.6. This stream is located in the Western Himalayas. Larvae of the new species were collected from the stony bottom along the edges of the Chenab River.