Rhodostrophia borealis (Swinhoe, 1890)

Kumari, Shabnam, Bandyopadhyay, Uttaran, Uniyal, Virendra Prasad, Chandra, Kailash & Hausmann, Axel, 2024, Integrative taxonomic review of the genus Rhodostrophia Hübner, 1823 and its allied genus Tanaotrichia Warren, 1893 (Lepidoptera: Geometridae) from the Western Himalaya, Zootaxa 5519 (1), pp. 59-89 : 66-68

Rhodostrophia borealis (Swinhoe, 1890) , stat. n.

[ Figs 4–7 , 34, 41 , 48, 55 ]

[TL: Kashmir; Kulu, Himachal Pradesh, India]

= bicolor rhoda Prout, 1912–1916, [TL: Chitral, Pakistan; Goorais Valley, Kashmir; Koksar, Lahaul and Spiti, Himachal Pradesh].

Phyletis cinerascens borealis Swinhoe, 1889 ; Proceedings of the Zoological Society of London: 427, pl. 44, fig. 8.

Rhodostrophia cinerascens borealis ; Prout, 1913; In: Seitz, A. (Ed.) (1912–1916): The Macrolepidoptera of the world, 4: 40.

Rhodostrophia cinerascens borealis ; Prout, 1938; In: Seitz, A. (Ed.) (1920–1941): The Macrolepidoptera of the world, 12: 143, pl. 15, fig. b.

Rhodostrophia cinerascens borealis ; Wiltshire, 1967; 26: 146, pl. 9, fig. 27 (♂ genitalia).

Material examined: INDIA: 3♂♂, Himachal Pradesh, Dist. Lahaul and Spiti, Lahaul Valley , Shashur Gompa , 32.57913° N, 077.02896° E, 3470 m, 27. VI.2021 ; 2♂♂, Dhok , 32.69587° N, 077.2206° E, 3736 m, 29. VI.2021 ; 2♂♂, 1♀, Jispa , 32.64262° N, 077.18973° E, 3327 m, 30. VI.2021 ; 1♂, 2♀♀, Pyukar , 32.55355° N, 077.07565° E, 3289 m, 03.VII.2021 ; 3♂♂, 1♀, Kolong , 32.59219° N, 077.13137° E, 3519 m, 02.VII.2021 ; 1♂, 2♀♀, Lobar , 32.71338° N, 076.66903° E, 2773 m, 07.VII.2021 ; 1♂, Naingar , 32.73166° N, 076.86569° E, 3491 m, 23.VII.2021 ; 2♂♂, 2♀♀, Spiti Valley, Chicham , 32.33903° N, 077.98894° E, 4026 m, 04.VIII.2021 ; 3♂♂, 1♀, Kibber , 32.34908° N, 078.03315° E, 4516 m, 05.VIII.2021 ; 6♂♂, Tashigang , 32.31392° N, 078.05563° E, 4870 m, 06.VIII.2021 ; 2♂♂, 2♀♀, Mudh , 31.95611° N, 078.03444° E, 3737 m, 07.VIII.2021; leg. S. Kumari.

Additionally, India: 25♂♂ and 6♀♀, Himachal Pradesh; 26 from Spiti valley, 7 km SE Kaza, 4150 m, 18.VII.1994, leg. P. Kautt and V. Weisz; 5 from Parahio Valley , 3 km SE Kaza, 3900 m, 30.VI.1994; leg. P. Kautt and V. Weisz (in SNSB-ZSM collection) .

NWR specimens: INDIA: 1♂, Himachal Pradesh, Dist. Lahaul and Spiti, Lahaul valley , Shashur Gompa, 32.5806° N, 077.02552° E, 3534 m, 26. VI.2021 ( BOLD Sample Id: BC_ ZSM _ Lep _117572) ; 2♂♂, Shashur Gompa , 32.57913° N, 077.02896° E, 3470 m, 27. VI.2021; 1♂, Dhok , 32.69587° N, 077.2206° E, 3736 m, 29. VI.2021; 1♂, Dhok , 32.69587° N, 077.2206° E, 3736 m, 29. VI.2021 ( BOLD Sample Id: BC_ ZSM _ Lep _117584) ; 1♂, Jispa , 32.64262° N, 077.18973° E, 3327 m, 30. VI.2021; 1♂, Trilokinath , 32.6788° N, 076.68676° E, 3238 m, 06.VII.2021 ( BOLD Sample Id: BC_ ZSM _ Lep _117573) ; 1♀, Trilokinath , 32.6788° N, 076.68676° E, 3238 m, 06.VII.2021 ( BOLD Sample Id: BC_ ZSM _ Lep _117580) ; 1♀, Duling , 32.65684° N, 076.80959° E, 3047 m, 11.VII.2021 ( BOLD Sample Id: BC_ ZSM _ Lep _117581) ; 1♂, Spiti Valley, Chicham , 32.33903° N, 077.98894° E, 4026 m, 04.VIII.2021 ; 1♀, Chicham , 32.33903° N, 077.98894° E, 4026 m, 04.VIII.2021 ( BOLD Sample Id: BC_ ZSM _ Lep _117582) ; 1♀, Chicham , 32.33903° N, 077.98894° E, 4026 m, 04.VIII.2021 ( BOLD Sample Id: BC_ ZSM _ Lep _117583) ; 2♂♂, Kibber , 32.34908° N, 078.03315° E, 4516 m, 05.VIII.2021 ; 1♂, Tashigang , 32.31392° N, 078.05563° E, 4870 m, 06.VIII.2021 ( BOLD Sample Id: BC_ ZSM _ Lep _117585) ; leg. S. Kumari.

Description:

Forewing length: Male: 17–19 mm, Female: 15–17 mm.

Antennae filiform in female; quadripectinate in male, flagellum slightly dentate and brown ventrally, basal one-third whitish dorsally. Vertex ochreous. Frons reddish-brown. Palpi short, upwardly directed, not reaching the frons and pale ochreous laterally. Collar, tegulae, patagia and thorax greyish-ochreous, sometimes with reddish-brown irroration; abdomen pale ochreous. Ventral side pale ochreous; legs with greyish-brown suffusion; femoral part of the legs and ventral side of the thorax with rose-red or vinous irroration. Legs features typical of the genus; foretibia with a well-developed median epiphysis; hindtibia in males with three tibial spurs; hair pencil absent. Forewing greyish-ochreous, sometimes reddish fawn-colour, apically elongated with obliquely straight outer margin; female forewing smaller, narrower and outwardly stretched with acute apex. Costa darker, sometimes with rose-red irrorations. Antemedial line greyish to red-brown, sinuous, often indistinct especially in males. Postmedial band oblique with irregular distal border, proximal border comparatively straight, slightly narrower towards inner margin, dark greyish-brown sometimes with rose-red irroration on the distinctly defined inner side; marginal band light grey, often obscure; area between the two bands paler, concolorous with ground colour. Terminal line dark grey. Cilia greyish-brown, distally paler. Discocellular dot small and black. Hindwing pale ochreous, markings as in forewing except antemedial line absent; postmedial band consisting of two distinct greyish-brown outwardly curved lines strongly bent at M1, area in between filled with lighter grey. Discocellular dot blackish-grey. Cilia as in forewing. Underside pale ochreous with fuscous suffusion in the forewing up to postmedial band; markings prominent except antemedial line not traceable in both wings; scattered rose-red irroration in hindwing and costal-half of forewing. Cilia darker than upper side (see figs 4–7).

Male genitalia ( Fig. 34 ): Uncus long; apex non-dilated, setose, and bilobed with large central concavity on distal margin. Gnathos non-sclerotised, triangular with small median process. Valva broad, symmetrical; apex sclerotised, spinulose, forming short, digitate process. Costa slightly curved and sclerotised. Sacculus sclerotised, folded ventrally over the valva; basally bulbed; apical half separated from valva, developed as a long, thick, slender, highly curved arm, tip modified as a thick, sclerotised, rounded plate. Juxta sclerotised, tongue-shaped with strongly sclerotised and irregular distal margin. Aedeagus ( Fig. 41 ) strongly sclerotised, apical half curved; vesica without cornuti. Posterior margin of the 8 th abdominal sternite ( Fig. 48 ) moderately sclerotised, bilobed with deep incision.

Female genitalia ( Fig. 55 ): Papillae anales ovally-elongated, setose, posterior margin with small central concavity; posterior apophyses three times the length of anterior apophyses. Ductus bursae strongly sclerotised, slightly curved, almost the length of corpus bursae. Antrum shallow without any deep invagination. Corpus bursae rounded to oval; signum consists of two strongly sclerotised, parallel, elongated, flat sclerites with acute tips, located anteriorly at the junction with ductus bursae. 7 th sternite sclerotised; posterior margin strongly concave, two blunt, short, horn-shaped projections on the sides.

Remarks: We encountered a few individuals with similar markings except their overall appearance is distinctly more rose-red. The forewing markings, especially the postmedial band, exhibit a much greater rose-red hue on the inner side than the usual greyish-brown. Both the antemedial line and costal markings showed pronounced rose-red suffusions. Moreover, the cilia on both wings and the underside of these specimens displayed a more prominent suffusion of rose-red.

Additionally, we studied the distinct external morphology and genitalia-based diagnostic features of R. borealis compared to R. cinerascens . The differences found (listed below) provide sufficient evidence for species-level differentiation. Therefore, here we propose a new taxonomic status for R. borealis upgrading it from subspecies to species level. However, this change will require future re-consideration following barcode sequencing of R. cinerascens .

Differential diagnosis: Adults of the R. borealis show a very close morphological resemblance to R. cinerascens ( Figs 8, 9 ). However, R. borealis has a slightly paler ground colour, well-developed discocellular dots, a comparatively straighter postmedial band on the forewing and a more distinctly marked postmedial band on the hindwing. Underside with less dark suffusion at the base of the wings and postmedial band better marked on the forewing (cf. Prout 1913). Male genitalia with valva spinulose apically; apical digitate process slightly longer and rounded apical plate of the saccular arm slightly larger (valva not spinulose apically; apical digitate process shorter and rounded apical plate of the saccular arm smaller in R. cinerascens , Fig. 35 ). Postmarginal groove of the 8 th sternite shallower (thin, deeper and less sclerotised in R. cinerascens , Fig. 49 ). Aedeagus is curved in the apical half (only slightly curved apically with straight medial region in R. cinerascens , Fig. 42 ). F emale genitalia of R. borealis has a sclerotised ductus bursae without deep invagination at the antrum (more membranous and with a deep Ushaped invagination at the antrum in R. cinerascens , Fig. 56 ) and signum somewhat shorter than in the latter.

Distribution: India: Himachal Pradesh [Kullu and Koksar (Lahaul and Spiti)], Jammu and Kashmir (Gurez Valley, Eastern Kashmir), Uttarakhand (Mussoorie) ( Prout 1913, 1938). Elsewhere: Not documented.

Genetic data: BIN: BOLD:AAJ5407. Mean and maximum intraspecific genetic divergences are 0.25% and 0.55% respectively. Two further BINs (AFI0862; AFI5687) preliminarily drawn here because of well-matching genitalia, but showing large distances of 7.0–8.4% from typical R. borealis (BOLD:AAJ5407) in BOLD barcode gap analysis and thus, require further integrative study. Both these BINs exhibit 6.74% genetic distance from R. tumulosa and further, AFI0862 is diverging by 6.57% from R. adauctata .

Bionomics: Adults of this species have been predominantly recorded to the east of the Pir-Panjal Mountain range, primarily in the Trans Himalayan region of Jammu and Kashmir, Ladakh and Lahaul and Spiti (Himachal Pradesh) ( Prout 1913, 1938). They usually fly from July to September ( Prout 1913) and have been recorded in large abundance in the cold desert of the Spiti valley (as a single dominant species during the primary field surveys of the first author in the region). The elevational distribution ranges from 3000–5000 m in the Himalayan Dry Temperate forests (13/C2b, C4, C5), Moist Alpine (15/C1) and Alpine Scrub (16/C1, E1) habitats, with a median distribution at ~ 3500 m.

Figures

FIGURES 4–16. Habitus images of Rhodostrophia spp. 4–7. R. borealis (4a–4b: Male, 5a–5b: female, 6a–6b: Male, Syntype, NHMUK, 7a–7b: Female, Syntype, NHMUK. 8–9. R. cinerascens* (8: Male, 9: Female). 10–12. R. herbicolens (10a–10b: Male, 11a–11b: Female, 12a–12b: Female, Syntype, NHMUK), 13–14. R. muricolor (13a–13b: Male, Syntype, NHMUK, 14a–14b: Female, Syntype, NHMUK). 15–16. pelloniaria (15a–15b: Male, 16a–16b: Female). *Specimens and genitalia slide at ZSM-SNSB, Munich; slides and photos prepared by Dr Axel Hausmann.

FIGURES 34–47. Male genitalia images of Rhodostrophia and Tanaotrichia spp. 34–41. Male Clasping organ (CLA). 34. R. borealis, 35. R. cinerascens*, 36. R. herbicolens, 37. R. pelloniaria, 38. R. stigmatica, 39. R. tristrigalis, 40. T. prasonaria trilineata. 41–47. Male aedeagus. 41. R. borealis, 42. R. cinerascens*, 43. R. herbicolens, 44. R. pelloniaria, 45. R. stigmatica, 46. R. tristrigalis, 47. T. prasonaria trilineata. *Specimens and genitalia slide at ZSM-SNSB, Munich; slides and photos prepared by Dr Axel Hausmann.

FIGURES 48–62. Male genitalia images of Rhodostrophia and Tanaotrichia spp. 48–54. Male 8th Abdominal Sternite. 48. R. borealis, 49. R. cinerascens*, 50. R. herbicolens, 51. R. pelloniaria, 52. R. stigmatica, 53. R. tristrigalis, 54. T. prasonaria trilineata. 55–62. Female genitalia images of Rhodostrophia and Tanaotrichia spp. 55. R. borealis, 56. R. cinerascens*, 57. R. herbicolens, 58. R. pelloniaria, 59. R. stigmatica, 60. R. tristrigalis, 61. R. vinacearia, 62. T. prasonaria trilineata. *Specimens and genitalia slide at ZSM-SNSB, Munich; slides and photos prepared by Dr Axel Hausmann.