Tenuibaetis kangi Kubendran, Vasanth & Subramanian, 2022

Kubendran, T., Vasanth, M., Subramanian, K. A., Gattolliat, Jean-Luc, Selvakumar, C., Jabeen, Fatima & Sinha, Bikramjit, 2022, Two new species and two new records of the genus Tenuibaetis Kang & Yang, 1994 (Ephemeroptera: Baetidae) from Indian Himalaya, Zootaxa 5196 (4), pp. 511-534 : 517-518

Tenuibaetis kangi Kubendran, Vasanth & Subramanian sp. nov.

( Figs 1C , 4A–G , 5A–H , 6A–E )

Material examined. Holotype. Mature larva, INDIA, Himachal Pradesh, Kangra district, Baijnath , tributary of Beas River , 32°01′27″ N, 76°23′28″ E, 13.XI.2019, Alt. 998 m. Coll. T. Kubendran and Fatima Jabeen (Reg. No. HARC /I-7626) . Paratypes. 1 male and 1 female imago reared from larvae, 18 larvae same data as holotype (Reg. No. HARC /I-7645) .

Description. Mature larva ( Fig. 1C ). Body length 5.3–5.8 mm; cerci length 2.8–3.2 mm; paracercus length 1.8–2.2 mm; antenna 1.5× as long as head capsule length.

Coloration. Head uniformly brown, medially pale white; brown with light yellow transverse band on the posterior half of mesonotum as in ( Fig. 1C ). Dark or light brown tergal color pattern typical of the genus, with a pale-yellow transverse band on the posterior half of mesonotum, two paired pale-yellow maculae on abdominal terga IV–V and terga IX–X pale yellow, cerci light brown without a brown band at ca. ½ of cerci. Thorax and abdomen ventrally brownish white, brighter than dorsally. Legs light brown; femur dorsally pale and light brown apically, distomedially brown; claws distally brownish.

Morphology. Antenna ( Fig. 4G ). Scape and pedicel sub-cylindrical, flagellum with thin and simple setae on apex of each segment.

Labrum ( Fig. 4A ). Subrectangular with length 0.7× maximum width. Medial emargination of distal margin with a small, apically pointed process. Dorsally with many medium, fine, simple setae; submarginal arc of setae composed of 1+3 simple setae. Ventrally with marginal row of setae composed of lateral and anterolateral long, feathered setae and medial long, bifid, pectinate setae; ventral surface with three short, spine-like setae near lateral and anterolateral margin.

Right mandible ( Fig. 4C ). Incisors fused. Outer and inner sets of denticles with 3+3 denticles each. Prostheca slender, distolaterally denticulate. Margin between prostheca and mola without tubercle. Tuft of setae at apex of mola present.

Left mandible ( Fig. 4D ). Incisors fused. Outer and inner sets of denticles with 3+3 denticles each. Prostheca robust, apically with small denticles and comb–shape structure. Margin between prostheca and mola straight. Subtriangular process long and slender, above level of area between prostheca and mola. Denticles of mola apically constricted. Tuft of setae at apex of mola present. Both mandibles with lateral margins almost straight; basal half with fine, simple setae scattered over dorsal surface.

Hypopharynx ( Fig. 4B ). Lingua as long as superlingua. Lingua about as broad as long covered with short, thin setae, distal half not expanded. Superlingua rounded, lateral margin rounded with thin, setae along distal margin and short, pointed setae along lateral margin.

Maxilla ( Fig. 4E ). Galea-lacinia with two simple, robust apical setae under crown; apically with three canines, lacinia with two rows of setae, one row with abundant thin setae ending with stout and long setae, second row with fine, long stout setae. Inner dorsal row of setae with three dentisetae, distal dentiseta tooth-like; middle dentiseta slender and bifid; proximal dentiseta slender, biserrate and with proximal furcation strongly developed and abducted. Medially with one feathered spine-like seta and 4–5 long, simple setae. Maxillary palp slightly longer than galealacinia; two segmented. Segment I equal in length to segment II. Apex of segment II rounded without nipple and without excavation at inner distolateral margin. Setae on maxillary palp fine and simple over surface of segments I and II.

Labium ( Fig. 4F ). Glossa basally broad, narrowing towards apex; shorter than paraglossa; inner margin with 10 spine-like setae increasing in length distally; apex with three robust pectinate setae; outer margin with 6 long, spine-like setae increasing in length distally; ventral surface with small medium, simple scattered setae. Paraglossa subrectangular slightly curved inward; apex rounded with three rows of long, robust distally pectinate setae in apical area and three medium simple setae in antero-medial area. Dorsally with a row of 6–7 long, spine-like setae near inner margin. Labial palp 3-segmented; segment I shorter 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 fine medium simple setae; segment III conical, slightly asymmetrical with a small concavity at inner apex; covered with short, stout, spine-like setae. Segments I, II and III with fine simple setae scattered over dorsal surface.

Hind wing pads. Present, well developed.

Foreleg ( Fig. 5A ). Ratio of foreleg segments 1.3:1.0:0.6:0.3. Femur length ca. 3× maximum width. Dorsal margin with a row of ca 24–25 long, stout, apically rounded setae; length of setae 0.25× maximum width of femur. Apex rounded with a row of 5–6 short, clavate setae and two groups of short, stout, pointed setae. Anterior surface with six robust setae and four small setae towards medially. Stout, lanceolate setae along ventral margin; villopore well developed. Dorsal margin of tibia with a row of fine simple setae; ventral margin with a row of short, spinelike setae, on apex one stout, pointed seta and a tuft of fine, simple setae; anterior surface scattered with stout, short, spatulate setae. Dorsal margin of tarsus with hair-like setae; ventral margin with 11–12 stout setae increasing in length towards apex, apex with one short, stout, spine-like seta. Claw ( Fig. 5D ) with a row of 11 denticles; distally pointed, 6–7 stripes, subapical setae absent.

Middle leg ( Fig. 5B ). Dorsal margin with a row of ca 18–20 long, stout, apically rounded setae; length of setae 0.25× maximum width of femur. Dorsal margin of tarsus with hair-like setae; ventral margin with 11 stout setae increasing in length towards apex, apex with one short, stout, spine-like seta. Claw ( Fig. 5D ) with a row of 10 denticles; distally pointed, 7–8 stripes, subapical setae absent.

Hind leg. Femur, tibia and tarsus same as middle leg; tarsal claw same as foreleg.

Terga ( Fig. 5H ). Surface with irregular rows of U-shaped scale bases and scattered fine, simple setae. Posterior margin of tergum IV with apically rounded spines wider than long and with stripes.

Gills ( Figs 5F, G ). Single lamellate gills present on segments I–VII. Margin with small denticles intercalating fine, simple setae, poorly visible trachea. Gill I as long as 2/3 of length of segment II; gill IV as long as length of segment V and ½ of segment VI combined, 2.3× length of gill I; gill VII as long as length of segment VIII.

Paraproct ( Fig. 5E ). Distally not expanded, with 13–14 marginal stout spines.Surface scattered with microspores and fine simple setae, and with more patches of notched scales. Cercotractor with medium, marginal spines.

Male imago. ( Fig. 6A, C–E ). Length: body 7.0– 7.2 mm; forewing 6.5 mm. Foreleg ( Fig. 6A–B ): femur 1.4 mm; tibia 2.2 mm; tarsi 0.3 mm. Cerci 10.5–10.8 mm.

Head dark red; scape and pedicel medium to dark red; flagellum medium red; facetted surface of compound eyes reddish brown; lateral face reddish brown. Thorax: yellow to dark brown. Legs: femora, tibiae and tarsi bright yellow. Forewings ( Fig. 6C ) hyaline; pterostigma with 4 cross-veins generally reaching subcostal vein; double intercalary veins shorter than distance between corresponding main veins. Hind wings ( Fig. 6D ) with an erect costal spur at ¼ length of wing; two longitudinal veins reaching margin, none of them bifurcated. Abdomen: tergites I–VI pale yellow with a dark stripe parallel to distal margin, except VII–X light reddish without marking or pattern. Genitalia ( Fig. 6E ): with three-segmented gonopods, first and second segments almost fused, first segment without apophysis, abundant thin setae present on inner margin of second segment, third segment globular, forceps welldeveloped, apically flattened and without setae.

Female imago ( Fig. 6B ). Length: body 7.8 mm; forewing 6.6 mm; foreleg: femur 1.6 mm; tibia 2.2 mm; tarsi 0.4 mm. Cerci 10.7 mm;

Etymology. The new species is named after Dr. Kang ( Japan), who has first established the genus Tenuibaetis .

Distribution. North Western Himalaya (Himachal Pradesh), India.

Diagnosis. Larva. Tenuibaetis kangi Kubendran, Vasanth & Subramanian sp. nov. can be distinguished from all known species of Tenuibaetis by the following combination of characters: (i) tergal color pattern dark brown with pale yellow transverse band on the posterior half of mesonotum, terga I–III dark brown, terga VI–VII dark brown and IX–X pale yellow ( Fig. 1C ); (ii) labrum dorsal submarginal arc of setae composed with 1+3 simple setae ( Fig. 4A ); (iii) left mandible: canine with 3+3 denticles ( Fig. 4D ); (iv) galea-lacinia with two simple, robust apical setae under crown ( Fig. 4E ); (v) outer margin of paraglossa with 6 long, spine-like setae increasing in length distally; ( Fig. 4F ); (vi) forefemur dorsal margin with 23–25 long, stout, apically rounded setae, anterior surface with distally 6 robust setae and 4 small setae towards medially ( Fig. 5A ); (vii) claw with a row of 11 denticles, subapical seta absent ( Fig. 5D ); (viii) gill I as long as 2/3 of length of segment II; (ix) paraproct distally not expanded, 13–14 marginal spines, with more patches of notched scales ( Fig. 5E ).

Habitat. Tenuibaetis kangi sp. nov. collected in tributary of Beas River ( Fig. 14B ) (from 5.0– 5.5 m wide and 28–30 cm depth), near Baijnath village in the district of Kangra, Himachal Pradesh. This river is characterized by temperature ranges from 22–24 ° C at the time of sampling, average current velocity (0.9 m /sec) and mainly rock, gravel and pebbles at the bottom of river. The river banks covered with grasses. The new species of the larvae collected at an altitude of 998 m a.s.l. Usually specimens were collected on the surface of stones, gravel and submerged plants. Further specimens were found on surface of stones covered with filamentous green algae.

Figures

FIGURES 1. Larvae: A–B, Tenuibaetis himani sp. nov. A, color pattern, dorsal view; B, habitus, lateral view; C, Tenuibaetis kangi sp. nov., color pattern, dorsal view.

FIGURES 4. Larva: Tenuibaetis kangi sp. nov., dorsal view: A, labrum; B, hypopharynx; C, right mandible (arrow indicated denticles); D, left mandible (arrow indicated denticles); E, maxilla (arrow indicated dentiseta); F, labium; G, antenna.

FIGURES 5. Larva: Tenuibaetis kangi sp. nov., dorsal view: A, foreleg; B, mid leg; C, hind leg; D, claw; E, paraproct; F, gill II; G, gill IV; H, posterior margin of terga IV (arrow indicated U shaped spines).

FIGURES 6. Tenuibaetis kangi sp. nov.: A, male imago (lateral view); B, female imago (dorsal view); C, fore wing (male), dorsal view; D, hind wing (male), dorsal view; E, styliger and gonostyli dorsal view.

FIGURE 14. Distribution map of the genus Tenuibaetis in India.