Chadisra curvipenis N. Singh, Ahmad & Raha, 2021

Singh, Navneet, Ahmad, Jalil & Raha, Angshuman, 2021, A new species in the genus Chadisra Walker (Notodontidae: Periergosinae) from the Great Nicobar Island, India, Zootaxa 5068 (2), pp. 277-286 : 281-285

Chadisra curvipenis N. Singh, Ahmad & Raha , sp. nov.

( Figs 2 – 5 , 10 – 12 )

Holotype: ♂, India, Andaman and Nicobar Islands, Great Nicobar Island , S.W. Road, 12.xi.2018, leg. K. C. Gopi & Party (Coll. NZCZSI, 7969/H10).

Paratypes: 1♂, India, Andaman and Nicobar Islands, Great Nicobar Island, East West Road , 08.xi.2018 (Coll. NZCZSI, 7971/H10) ; 3♂, Shastri Nagar , 11.ix.2018 (Coll. NZCZSI, 7972/H10) ; 1♂, same data as holotype (Coll. NZCZSI, 7970/H10)

Diagnosis: Morphologically, C. curvipenis sp. nov. ( Figs 2 – 5 ) is similar to widely distributed species C. bipartita and C. bipars ( Figs 6 – 9 ), but it is distinct by the forewing with marginal area inwardly extended along the inner margin, with an apical, small, black, claw-shaped mark protruding into the baso-medial pale yellow-brown patch (less conspicuous in dark form); presence of two distinct black specks within the obscure greyish reniform patch and smaller in wingspan. The new species is further distinct from C. bipars in having much less yellowish-green suffusion on the outer area of the forewing and a much paler hindwing. In male genitalia, C. curvipenis sp. nov. ( Figs 10–12 ) is remarkably different from C. bipartita ( Figs 13–15 ) and C. bipars ( Figs 16–18 ) by the presence of a much broader and larger uncus with typically produced latero-dorsal edges; longer and outwardly curved socii (shorter in C. bipars and much more robust, broader and inwardly curved in C. bipartita ); doubly curved (approximately s-shaped) aedeagus with a large subapical and a minute apical spines (aedeagus of C. bipartita and C. bipars are somewhat straight and without spines). In addition, the 8 th sternite of the new species is highly concave at the distal border with a small medial, acute projection and lateral dentate edges. Whereas, the 8 th sternite of C. bipars ( Fig. 17 , above) has a sinuous distal edge and that of C. bipartita ( Fig. 14 , above) is distally straight with a medial depression ( Schintlmeister 2008).Among the other Sundanian species, C. calapana , C. basivacua and C. borneensis are similar to the new species. Chadisra calapana is a variable species with both sexes showing multiple phenotypes even from the same locality. Schintlmeister & Laurens (2010) established C. luzonensis Kiriakoff, 1970 as a junior synonym of C. calapana by examining more than 300 adults from Philippines. Externally, C. calapana is difficult to distinguish from the Sri Lankan C. basalis ( Moore, 1883) and the Sulawesian C. vittata ( Kiriakoff, 1970) , but the male genitalia are defining. However, C. basalis ( Moore 1883: 113, pl. 121, fig. 1) is clearly distinct from C. curvipenis sp. nov. by the presence of a medial purple-brown band on its forewing whose inner border is angled below the cell and delineated by a black line and the outer border by a distinct pale line. This purple-brown band is traversed by black streaks on its outer half and its hindwing is pale olivaceous-brown, the colour being palest at the base. Externally, the Luzon ( Philippines) population of C. calapana closely resembles the C. curvipenis sp. nov. but it is distinct by the forewing without the black claw shaped mark (near inner margin) and also the absence of two small black reniform specks (both marks are present in the forewing of C. curvipenis sp. nov.). In the male genitalia, C. curvipenis sp. nov. is clearly distinct from C. calapana ( Kiriakoff 1970: 121, fig. 16), C. basivacua ( Kiriakoff 1967b: 58, fig. 22) and C. borneensis ( Holloway 1983: 80, figs 78, 78a) by the presence of broader uncus with extended latero-dorsal edges and moderately large and curved socii. The uncus of C. calapana is somewhat circular, partially bilobed with a pair of very large socii, while in C. basivacua the uncus is very long, slender, and apically blunt with long socii and in C. borneensis it is much shorter, narrower and apically blunt with broader and triangular socii. The aedeagus represents the most distinctive characters which is doubly curved (somewhat s-shaped) with a large subapical and a minute apical spine in C. curvipenis sp. nov., whereas, it is robust, straight, proximally widened with two lateral spinous projections and a prominent spade-shaped subterminal process in C. calapana . The aedeagus of C. basivacua is slender, slightly s-shaped with broader apex and that of C. borneensis it is somewhat straight, long and narrower. Another closely related species, C. vittata ( Kiriakoff 1970: 120, fig. 20) differs from the new species by the characteristically broad and almost triangular socii and a robust aedeagus bearing two apical processes.

Description. Male: Head: covered with cupreous brown piliform scales; antennae pectinate up to tips, rami short and white, shaft brown, base of antennae with raised brown scales interspersed with yellow scales; palpi porrect, covered dorsally with dark brown and ventrally with ochreous scales.

Thorax: covered with bright yellowish-brown scales dorsally, collar region slightly darker than rest of thorax, sternum cupreous brown, sometimes with ochreous scales; legs brown, covered with long golden yellow or brownish-yellow scales, tarsi dark brown, unscaled, having yellow segmental bands. Wings: Forewing length: ♂ 17–18 mm. Forewing elongated (length: width = 2:1) with oblique outer margin. Dorsally, baso-medial area pale yellowish-brown, costa of pale baso-medial area dark brown with short black streaks, outer border of this baso-medial area oblique until CuA2 then sharply bending inward and running parallel to inner margin just anterior to 3A+2A then bending downward to meet inner margin at around 1/3 rd distance from base; a small, black claw-like mark at lower border of baso-medial patch below cell in interspace between M and 3A+2A; medial line black, sinuous, oblique from costa to CuA1, running along outer border of baso-medial pale patch, anterior part of medial line inwardly shaded with reddish-brown; remainder of forewing greenish-brown, greenish tinge being slightly more pronounced towards costa and apex; an indistinct reniform patch having pale grey outline, former with two black specks on it; postmedial line curved, sinuate, distinct from costa to R5 and then obscure to inner margin, rest of postmedial line barely visible and pale brown; pale subapical semicircular patch at costa having two nearly parallel black streaks within it; submarginal series of specks present in interspaces between veins; marginal line thin, black; cilia chequered with brown and black. Hindwing dorsally ochreous; inner and submarginal areas irrorated with fuscous; small black anal patch; thin marginal black line; cilia brown with white tips. Underside of forewing with basal-medial yellowish-brown patch more reduced; remainder of area browner with slight greyish suffusion at the submarginal region; costa with four prominent subapical white spots; cilia distinctly chequered with pale and dark brown. Underside of hindwing whitish with slight brownish irrorations at the costal and outer area. Variation: Two specimens in the series have darker wing pattern where the baso-medial pale yellowish brown area of the forewing is suffused with dark reddish-brown scales and the hindwing is more irrorated with fuscous-brown ( Fig. 4 ).

Abdomen: Dorsal side of the abdomen covered with dark yellowish-brown piliform scales, ventral side paler. 8 th sternite broad, plate-like, distally well sclerotized, distal margin highly concave with a median small, acute projection and raised lateral sides having irregular dentations ( Fig. 11 ).

Genitalia: Uncus apically broad, plate-like, partially bifurcated, latero-distally extended and acute; Socii robust, outwardly curved, extending beyond half-length of uncus, small basal process present; tegumen robust, elongated, more or less straight; valva crescent-shaped, ventrally curved, costal margin highly convex, basal part well sclerotized with irregular minute dentations; juxta trapezoidal with dorso-lateral slender process on each side; vinculum broad, well sclerotized, u-shaped; saccus strongly reduced ( Fig. 10 ); aedeagus stout, distal half highly curved with a large, broad subapical spine and a minute apical spine; vesica slightly sclerotized at its distal end ( Fig. 12 ).

Female: unknown.

Etymology: The species is named for its characteristically curved aedeagus which is more or less straight or not as strongly curved in other congeners.

Habitat: The Nicobar Islands are an archipelagic island group located at the eastern part of the Indian Ocean. The Great Nicobar Island (collection site of C. curvipenis sp. nov.) is the largest and the southernmost among the Nicobar group of islands. It covers an area of nearly 920 sq. km with a coastline of 202 km and is situated 180 km North-West of Sumatra and to the East separated from Thailand by the Andaman Sea. It falls in the Sundaland biodiversity hotspot and most of its area is designated as the Great Nicobar Biosphere Reserve (in 1989 by UNESCO under the Man and Biosphere Reserve Programme (MAB)). The island is sparsely inhabited and is majorly covered by rainforest. Typically, the vegetation of the Great Nicobar Island is classified into the coastal mangrove forests, evergreen, semi-evergreen and moist deciduous tropical and subtropical broadleaf forests. Owing to their location and climate, the Nicobar Islands are recognised as a distinct terrestrial ecoregion, with exceptionally rich biodiversity and high degree of endemism. Among the 944 insect species reported from Nicobar, Lepidoptera is the most species rich order with a total of 276 species including 143 species of butterflies and 133 species of moths ( Chandra et al. 2018a). The low diversity records are due to the under exploration and can only be considered as a tip of an iceberg. The discovery of C. curvipenis sp. nov. is also the first ever documentation of Notodontidae from the Nicobar islands.

Figures

FIGURES 2–9. Habitus of Chadisra spp. 2–5, C. curvipenis sp. nov. (diagnostic characters indicated with black lines): 2–3, male, dorsal and ventral sides (HT), 4–5, male, dorsal and ventral sides (PT); 6–7, C. bipartita male, dorsal and ventral sides (Dharamsala, Himachal Pradesh, India, leg. A. Raha, K. Mallick & U. Bandyopadhyay); 8–9, C. bipars male, dorsal and ventral sides (Dihang-Dibang Biosphere Reserve, Arunachal Pradesh, India, leg. S. Gayen & B. A. Laskar).

FIGURES 10–18. Male genitalia of Chadisra spp. 10–12, C. curvipenis sp. nov. (HT): 10, ventral view, 11, sternite (above) and tergite (below) of 8th abdominal segment, 12, aedeagus (diagnostic characters indicated with black lines); 13–15, C. bipartita: 13, uncus and socii ventral view, 14, sternite (above) and tergite of 8th abdominal segment (below), 15, aedeagus; 16–18, C. bipars: 16, uncus and socii ventral view, 17, sternite (above) and tergite (below) of 8th abdominal segment, 18, aedeagus (all unscaled)