Tenuibaetis himani 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 : 512-514

Tenuibaetis himani Kubendran, Vasanth & Subramanian sp. nov.

( Figs 1A–B , 2A–I , 3A–I )

Material examined. Holotype. Larva, INDIA, Himachal Pradesh, Kinnaur district, Baspa River , Sangla Valley , 31°25′09″ N 78°16′07″ E, Alt. 2600 m. 27.IX.2017, Coll. T. Kubendran (Reg. No. HARC /I-6190) . Paratypes. 3 larvae, same data as holotype (Reg. No. HARC /I-6191) .

Description. Mature larva ( Figs 1A–B ). Body length: 4.2–4.4 mm; cerci length 2.5–3.0 mm; paracercus length 1.5 mm; antenna 1.2× as long as head capsule length.

Coloration. Head uniformly brown with a pair of medially pale white; brown with light yellow transverse band on the posterior half of mesonotum; base of clypeus pale yellow ( Fig. 1A ); 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. 3C ). Scape and pedicel sub-cylindrical, flagellum with thin and simple setae on apex of each segment.

Labrum ( Fig. 2A ). 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+4 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 two short, spine-like setae near lateral and anterolateral margin.

Right mandible ( Figs 2B, C ). 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 ( Figs 2D, E ). Incisors fused. Outer and inner sets of denticles with 3+4 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. 2F ). Lingua approx. as long superlingua. Lingua longer than broad, distal half not expanded. Superlingua rounded, lateral margin rounded with thin setae along distal margin.

Maxilla ( Figs 2G, H ). Maxilla apically with three canines and three dentisetae, 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, bifid and serrate; 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 galea–lacinia; 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.

Labium ( Fig. 2I ). Glossa shorter than paraglossa; inner margin with 6 spine-like setae. Most apical setae much longer than other setae; apex with one long, robust, spatulate setae and one medium, robust seta; outer margin with 4–5 spine-like setae, base with simple setae. Paraglossa 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 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 II and III with fine simple setae scattered over dorsal surface.

Hind wing pads ( Fig. 3D ). Present, well developed.

Foreleg ( Fig. 3F ). Ratio of foreleg segments 1.1:1.0:0.5:0.2. Femur length ca. 3× maximum width. Dorsal margin with a row of ca 16–17 long, stout, apically rounded setae; length of setae 0.25× maximum width of femur. Apex rounded with a row of short, stout, pointed setae, many stouts lanceolate setae on lateral surface. Villopore well developed. Dorsal margin of tibia with a row of fine simple setae, stout setae absent; ventral margin with a row of 6–7 spine-like setae and a tuft of long, fine, simple setae; anterior surface scattered with stout, short, spatulate setae. Dorsal margin of tarsus with hair–like setae; ventral margin with 9–10 stout setae increasing in length towards apex. Claw ( Fig. 3G ) with a row of 11 denticles; distally pointed, 6–7 stripes, subapical setae absent.

Terga ( Fig. 3A–B ). Surface with irregular rows of U-shaped scale bases and scattered fine, simple setae, with stripes and tergum IX irregular spines apically.

Gills ( Fig. 3H, I ). Single lamellate gills present on segments I–VII. Margin with small denticles intercalating fine, simple setae. Abdominal gills I, II, VI and VII without visible trachea and III–V with poorly visible trachea. Tracheae limited to proximal part of main trunk.

Paraproct ( Fig. 3E ). Distally not expanded, with 12–13 marginal stout spines. Surface scattered with micropores and fine simple setae, and with a patch of notched scales. Cercotractor with medium, marginal spines.

Imago. Unknown.

Etymology. The new species is named after the type locality located near snow (Himani meaning snow in Hindi), in the state of Himachal Pradesh, India.

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

Diagnosis. Larva. Tenuibaetis himani Kubendran, Vasanth & Subramanian sp. nov. can be distinguished from all known species of Tenuibaetis by the following combination of characters: (i) dark and light brown tergal colour 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 ( Figs 1A–B ); (ii) labrum dorsal submarginal arc of setae composed of one plus four simple setae ( Fig. 2A ); (iii) right mandible: canine with 3+3 denticles, prostheca slender, apically denticulate ( Figs 2B–C ); (iv) left mandible: canine with 3+4 denticles ( Fig. 2D ); (v) maxilla: distal dentiseta slender, trifid and pectinate; middle dentiseta slender, bifid and serrate; proximal dentiseta slender, biserrate and with proximal furcation strongly developed and abducted ( Fig. 2H ); (vi) labial palp segment II slightly produced inward to form a moderately expanded lobe at distal corner, segment III conical, slightly asymmetrical with a small concavity at inner apex ( Fig. 2I ); (vii) fore femur dorsal margin with 16–17 long, stout, apically rounded setae, anterior surface with a row of robust setae with median spine-like setae ( Fig. 3F ); (viii) claw with a row of 11 denticles, subapical seta absent ( Fig. 3G ); (ix) abdominal gills I, II, VI and VII without trachea and III–V with poorly developed trachea ( Figs 3H, I ); (x) paraproct distally not expanded, 12–13 marginal spines, surface with a patch of notched scales ( Fig. 3E ).

Habitat. Tenuibaetis himani sp. nov. was collected in Baspa River ( Fig. 14A ) (from 3.5–5 m wide and 16–17 cm depth), Sangla Valley. This river is characterized by medium temperature 15–18 ° C and relative humidity 30–33% at the time of sampling, average current velocity (0.5 m /sec) and mainly gravel and pebbles at the bottom of river.

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 2. Larva: Tenuibaetis himani sp. nov., details of mouthparts: A, labrum (right part-dorsal view, left part-ventral view); B–G dorsal view; right mandible; C, right prostheca; D, left mandible; E, left prostheca; F, hypopharynx; G, maxilla; H, maxilla (arrow indicated dentiseta); I, labium (right part-dorsal, left part-ventral).

FIGURES 3. Larva: Tenuibaetis himani sp. nov., dorsal view: A, posterior margin of tergum IV; B, posterior margin of tergum IX; C, antenna; D, hind wing pads; E, paraproct; F, foreleg; G, claw; H, gill IV; I, gill VII.

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