Notacanthurus pange Vasanth, Selvakumar & Subramanian, 2020

Vasanth, M., Selvakumar, C., Subramanian, K. A., Sivaramakrishnan, K. G. & Sinha, Bikramjit, 2020, A new species of Notacanthurus Tshernova, 1974 (Ephemeroptera: Heptageniidae) from India, Zootaxa 4894 (3), pp. 437-444 : 438-442

Notacanthurus pange Vasanth, Selvakumar & Subramanian sp. nov.

( Figs 1–19 )

Material examined. Holotype: Ƌ larva, INDIA, Arunachal Pradesh, Lower Subansiri district, Talley Valley Wildlife Sanctuary, Pange , 27.5485 N, 93.89756 E, 1851 m, 18.vi.2017, colls. K. A. Subramanian & M. Vasanth (I/E- 440) . Paratypes: 2 larvae, same data as holotype (I/E-441) ; 4 larvae, Arunachal Pradesh, Lower Subansiri district, Duskilo river , 27.62776 N, 93.8437 E, 1662 m, 16.vi.2017 , colls. K. A. Subramanian & M. Vasanth (I/E-442); 3 larvae, Arunachal Pradesh, Dibang Valley, Talo river near Apai village , 28.10402 N, 96.10402 E, 1323 m, 29.x.2017, coll. K. A. Subramanian (I/E-443) ; 2 larvae, Sikkim, East Sikkim, Stream near Nathu La , 27.36718 N; 88.8400 E, 3856 m, 18.ix.2018, coll. K. A. Subramanian (I/E-444) ; 4 larvae, Meghalaya, East Jaintia hills, Daidung village , 25.33547 N, 92.61981 E, 1079 m, 12.iii.2016, coll. E. Eyarin Jehamalar.

Description. Mature male larva: Body length 7.8 mm, length of caudal filaments 8.6 mm ( Figs 1–2 ).

Head: Head subquadrate, brown, with irregular pale yellow markings ( Figs 1–2 ); anterior and lateral margins round; posterior margin concave; head width 3.4 mm, head length 1.3 mm; eyes black, antennae pale brown. Labrum with anterior portion straight and laterally curved; dorsally with dense hair-like setae ( Fig. 4 ). Mandibles with scattered setae along molar area; incisor well developed; dense hair-like setae on anterolateral margin ( Figs 6–7 ). Maxillae with 19–20 comb-like setae on crown, with scattered hair-like setae on ventral surface; outer margin of maxillary palp segment 2 and 3 with long hair-like setal field; terminal segment of maxillary palp with dense hairlike setae ( Fig. 8 ). Hypopharynx: lingua apically broad and convex; superlinguae each with lateral arm developed, with dense row of hair-like setae ( Fig. 5 ). Labium with wide U-shaped division of glossae; glossae subquadrangular; paraglossae expanded laterally; apical segment of each labial palp acutely pointed, dorsal surface with dense row of setae ( Fig. 9 ).

Thorax: Thorax brown with scattered brown markings around basal wing pads; pronotum extended laterally, a little wider than head ( Fig 1–2 ), pronotum width 3.4 mm. Legs: Forefemora pale brown, with median pale yellowish maculae, scattered short simple stout setae on dorsal surfaces, apex of femora with blunt apical projection, with row of long setae on outer margin; fore tibiae subequal to femora in length, outer margin with few tiny and short setae at base, foretarsi 1/3 length of foretibiae ( Figs 10–11 ). Mid and hind legs ( Figs 12–13 ) similar to forelegs in color and setation; mid tibiae with dense setae on outer margin, tarsi 1/3 length of tibiae and hind tibiae with dense hair-like setae along the whole outer margin. Claws of all legs similar, with a large basal denticle and 2 subapical denticles ( Fig. 14 ).

Abdomen: Terga brown, with distinct oblique markings; terga I–IX each with single prominent median spine ( Fig 1–2 ), with row of short bristles on posterior margin ( Fig. 3 ). Sterna pale white; posterior end of sternum X with notched ( Fig. 19 ). Gills on segment I–VII; Gills with both lamellae and fibrilliform portion on abdominal segments I–VI ( Figs 15–18 ); gill VII with only lamellae; lamellae of gills I knife-shaped ( Fig. 15 ); gills II–VI each with oval shape anteriorly; gills V–VI each with accessory lobe ( Figs 17–18 ); gill VII narrower lanceolate, with fine hair-like marginal setae.

Genitals: Protopenis ( Fig. 19 ) male genitalia with simple, penis lobes fused, V shaped apically blunt with median pair of spine-like titillators subapically and mesally. Cerci about 1.2x length of body, each segment with whorls of minute bristles and without interfacing setae.

Diagnosis: Notacanthurus pange sp. nov. can be distinguished from all known species of Notacanthurus by the following combination of characters: (i) gill lamellae V–VI with accessory lobe ( Figs. 17–18 ); (ii) dorsal surface of femora with scattered short simple stout setae ( Fig. 11 ); (iii) male genitalia having penis lobes fused, V shaped apically blunt with median pair of spine-like titillators subapically and mesally ( Fig. 19 ); (iv) labrum with anterior portion straight and laterally curved ( Fig. 4 ); and (v) lingua of hypopharynx apically broad and convex ( Fig. 5 ).

Notacanthurus pange sp. nov. can be accommodated in the recent global larval key to the species of Notacanthurus by Zhang et al. (2020). The second part of the 5 th couplet of that key can be modified and a new couplet should be added to include Notacanthurus pange sp. nov. as follows:

5. Abdominal terga with oblique stripes...................................................................... 7 - Abdominal terga without distinct markings................................................................. 6 6. Dorsal surface of femora with apically blunt scattered stout setae.................................. N. pange sp. nov. - Dorsal surface of femora with apically pointed stout setae.............................................. N. baekdu

Imagos: Unknown.

Etymology: The species named after the type locality, Pange, Lower Subansiri district, Arunachal Pradesh state, India.

Habitat: The specimens were collected among cobbles from cold pristine hill streams between 1100-3860m. The riparian habitat ranged from subtropical broad leaved evergreen forests (Arunachal Pradesh and Meghalaya) to alpine meadows (Sikkim) ( Fig. 20 ).

Distribution: India (Arunachal Pradesh, Meghalaya and Sikkim) ( Fig. 21 ).

Figures

FIGURE 20. Habitat of Notacanthurus pange sp. nov. in East Sikkim.

FIGURE 21. Distribution of Notacanthurus pange sp. nov.

FIGURES 1–5. Larva of Notacanthurus pange sp. nov. 1. Dorsal view; 2. Lateral view; 2A. Close up of terga V –VII; 3. Abdominal segment V; 4. Labrum; 5. Hypopharynx.

FIGURES 6–13. Larva of Notacanthurus pange sp. nov. 6. Left mandible; 7. Right mandible; 8. Maxilla; 9. Labium; 10. Foreleg; 11. Scattered stout setae on the dorsal surface of fore femora; 12. Midleg; 13. Hindleg.

FIGURES 14–19. Larva of Notacanthurus pange sp. nov. 14. Claw; 15.Gill I. 16. Gill III; 17. Gill V; 18. Gill VI; 19. Abdominal sterna X of a male larva in ventral view (Arrow mark- ‘V’ shaped blunt titillators)