Cyana nigrilineata ( Hampson, 1900 )

Koshkin, Evgeny S., 2023, Description of the male of Cyana nigrilineata (Hampson, 1900) (Lepidoptera, Erebidae: Arctiinae), a little-known species endemic to Sumatra Island, Zootaxa 5375 (1), pp. 137-141 : 137-140

Cyana nigrilineata ( Hampson, 1900)

( Figs 1 A, B, C, D, H ; 2 A, B)

Chionaema nigrilineata Hampson, 1900: 311 , plate XXVII, fig. 2 (Type locality: “ Sumatra ”).

Material examined. 4 ♁, Indonesia, Sumatra Island , West Sumatra Province, Solok regency, Gunung Talang district, vicinities of Batang Barus desa, 00°58’ S, 100°36’ E, 1091–1200 m, 26– 28.03.2019, leg. E.S. Koshkin.

Description of the male. Adult. Wingspan 38.5–40 mm, forewing length 17–18 mm. Head white. Labial palps short, slightly curved, red. Proboscis well-developed, brown.Antennae red, scape covered with white scales. Thorax white, with oval red spot in central part. Patagium white, trimmed with red along margins. Tegula completely white. Abdomen light pink dorsally with yellow tint ( Fig. 1 A, B ). Legs white with brown-black and yellow-brown bands ( Fig. 1 H ). Protibia and mesotibia with dark brown bands. Tarsomeres of pro- and mesolegs with interrupted yellow-brown and white bands. Metalegs white with small yellow-brown sections in tarsomeres. Forewings white. Androconial lobe is located along costal margin. Subbasal red line thin, short, ending with rounded red spot at base of discal cell. Antemedial line thin, black with sparse red scales, curved inwards at end. Costal margin from antemedial line to almost base of wing is black. Postmedial line thin, black, but short section at beginning is red; it curved outwards in middle part. Discal spot black, rounded; in some specimens, smaller black spot below it. In discal cell before discal spot located large red spot of oval or triangular shape. Subterminal band red, slightly widened below. End of androconial lobe with red scales. Hindwings beige-pinkish, slightly darker at margins. Cilia white on fore- and hindwings ( Fig. 1 A, B ). Underside of wings white-pinkish with more intense pink oblong-rounded relief spot under androconial lobe ( Fig. 1 C ). Male genitalia. Uncus small, thin, apically pointed. Tegumen narrow, longer than uncus. Saccus wide, rounded. Valva long, narrow, with slightly dilated and rounded apex. Saccular process almost stout, quite narrow, not reaching the apex of the valva, with strong inward-curved apical spine. Aedeagus short, almost straight, with short unidirectional saccate vesica without cornuti ( Fig. 2 A, B ).

Distribution. Indonesia: Sumatra Island (West and Southwestern regions).

Ecology. Cyana nigrilineata inhabits mountain forests at altitudes of about 1100–1200 m ( Fig. 3 ).

Discussion. Male of Cyana nigrilineata differs from female in the presence of an androconial fold at the costal margin of the forewing, the more pronounced subbasal line, the non-serrated subterminal band, and the presence of a red spot in the discal cell. The similar differences between sexes are expressed in the most similar species C. malayensis (Hampson, 1914) ( Fig. 1 E, F ).

According to the external morphology and the structure of male genitalia, Cyana nigrilineata is most closely related to C. malayensis and C. barisana Roesler & Küppers, 1976 ( Fig. 1 E, F, G ). Cyana malayensis is distributed in Thailand, Peninsular Malaysia, Sumatra, Borneo and Palawan ( Roepke 1946; Bucsek 2012; Holloway 2001; Lourens 2017) while C. barisana occurs in Sumatra (type locality: «N-Sumatra b. Berastagi Umg. Kampong, 1350 m ») and Borneo ( Roesler & Küppers 1976; Holloway 2001). Thus, these three species co-occur in Sumatra, which is confirmed during current study ( Figs 1 , 3). Cyana nigrilineata differs from C. malayensis in the strong reduction of the red pattern elements on the forewing and thorax upperside, particularly in the absence of the red patterns along the antemedial and postmedial lines, on the tegulae, on the posterior margin of the dorsal side of the thorax, and also in the reduced subbasal line. Additionally, C. malayensis has a wider black antemedial line. The shape of the bends of the antemedial and postmedial lines are almost identical in these two species. Specimens of C. malayensis from Sumatra have a little variability in the shape of the lower bend in the antemedial line, from weakly ( Fig. 1 F ) to strongly curved (as in C. nigrilineata ). Cyana nigrilineata differs from C. barisana by the same features as from the previous species, as well as by the lack of black areas between the subbasal and antemedial lines, and between the postmedial line and the subterminal band. In turn, C. barisana differs from C. malayensis only in the presence of the aforementioned black areas ( Fig. 1 G ). The coloration of the underside of both wings and legs is almost identical in these three species ( Fig. 1 H, I, J ).

The male genitalia structures of these three species are also very similar ( Fig. 2 ). The saccular process of Cyana nigrilineata is narrower and straighter than in C. malayensis , in which it has a bend at outer margin and is sharply tapered towards to the apex ( Fig. 2 A–D ). The vesica of C. barisana is longer than in C. nigrilineata and C. malayensis , and zigzag curved whereas it is unidirectional in the congeners.

Figures

FIGURE 1. Cyana spp., habitus.A, B, C, D, H—C. nigrilineata; E, F, I—C. malayensis; G, J—C. barisana. A–C, F–J—males, D–E—females; A, B, D, E, F, G—dorsal view, C—ventral view, H, I, J—lateral view. Locality and date for all specimens (except D): Indonesia, Sumatra Island, West Sumatra Province, Solok regency, vicinities of Batang Barus desa, 26–28.03.2019. (Figures A–C & E–J by Evgeny Koshkin, D—C. nigrilineata type after Hampson, 1900).

FIGURE 2. Cyana spp., male genitalia. A, B—C. nigrilineata, C, D—C. malayensis, E—C. barisana. Collecting data as Fig. 1. Photos by Evgeny Koshkin.

FIGURE 3. Habitat of Cyana nigrilineata, C. malayensis and C. barisana: Indonesia, Sumatra Island, West Sumatra Province, Solok regency, vicinities of Batang Barus desa, 1165 m, 27.03.2019. Photo by Evgeny Koshkin.