Nexosa tonkinensis Heppner & Bae

Heppner, John B. & Bae, Yang-Seop, 2015, Review of Nexosa Diakonoff in Vietnam, with a new species and a new subspecies, and transfer to the tribe Archipini (Lepidoptera: Tortricidae: Tortricinae: Archipini), Zootaxa 3999 (1) : -

Nexosa tonkinensis Heppner & Bae , new species

( Figs. 2 , 5–6 , 8 )

Type locality. Cuc Phuong Natl. Park, Mac Lake (155m), Ninh Binh Prov., Vietnam.

Description. Wing expanse: 12.3 mm (n = 1). Male. Unknown. Female ( Fig. 2 ). Head ( Figs. 5–6 ): Vertex white and tan-fuscous, and neck white; frons white, with tan eye margins; antenna light tan alternating with dark brown, ventrally setous but unscaled; labial palpus white on both basal segments, with apical segment brownfuscous at middle, and mesally the same but less fuscous near apex. Thorax: Brown-fuscous; tegulae same; venter white, with white-tan at neck; legs white, with brown-fuscous on femurs and tibiae dorsally, with some brownfuscous on tarsal segments. Forewing brown-fuscous, with irrorated white area on dorsal middle, narrowing to tornus and half of basal area; costal margin with brown alternating with 6–7 tan strigulae, more whitish nearer apical quarter, with yellow line at apical 1/4 curved to tornus, margined by iridescent silver but becoming dull brown halfway to tornus; silver subterminal line; black spot near tornus with small light yellow spots; fringe dark fuscous, with white near apex and near tornus; venter of wing like dorsum but duller and more yellow marks on costa and apex. Hindwing white in basal half, brown-fuscous at base and some brown-fuscous irrorations near anal margin and angled beyond base; dark brown line at 1/3, angled midway to base; a large black patch along termen and tornus, with several small yellow and silver spots towards tornus and subterminal silver line; fringe white except brown-fuscous near apex and along tornal and anal margins; venter of wing like dorsum but duller. Abdomen: Brown-fuscous with pale white scale row on posterior margin of each tergite; venter cream-white; anal tuft fuscous. Female genitalia ( Fig. 8 ) elongated, with short ovipositor, papilla anales setous and flattened; sterigma 2-stepped quadratic and dorso-ventrally somewhat flattened, smaller at ductus entrance, more widened horizontally posteriorly, and with lateral extension and large setose lobe posterolateral to sterigma; ostium bursae ovate, simple, wider than deep; ductus bursae simple, of subequal width to bursa opening but somewhat sclerotized, with colliculum-like short collar anterior to ostium and by ductus seminalis-accessory bursa attachment; ductus seminalis emergent laterally from entrance duct of very large ovoid accessory bursa (nearly twice size of bursa), which is emergent from ductus bursae at posterior end of subostium (or colliculum); bursa copulatrix simple, oval, and with smooth walls; signum absent.

Specimens studied. Holotype female: Cuc Phuong Natl. Pk., Mac Lake (155 m), Vietnam, 4–7 May 2009, J. B. Heppner (genitalia slide JBH 3126). Deposited with FSCA/McGuire Center, on indefinite loan from PPRI (Hanoi, Vietnam).

Etymology. The species is named after Vietnam.

Biology. Like N. hexaphala , these moths are likely diurnal. Nothing is known of the life history and biology of the species.

Distribution. This species is known only from northern Vietnam.

Discussion. The new species superficially looks like the new genus related to Mictocommosis ( Heppner & Bae 2015) , but can be easily distinguished by its three silvery forewing apical lines, as in all Nexosa species (except N. picturata ), whereas the Mictocommosis relative has only two silvery apical lines. Also, N. tonkinensis has a prominent orange mark between the silvery lines, whereas in the Mictocommosis relative this area is dark brown. Likewise, the female genitalia are very different, with N. tonkinensis lacking the signum and ductus sclerotizations so prominent in Archipini . Unfortunately, the female genitalia of N. hexaphala remain unknown, but the congeneric species have female genitalia with many similarities to N. tonkinensis , as can be seen in the figures in Diakonoff (1977). The other two Asian Nexosa species, N. marmarastra and N. picturata , are very similar to N. tonkinensis , but differ in the longer orange mark of the forewing apical region, which is only half as long in N. tonkinensis , whereas the markings also differ in the lines of the basal half of the hindwing.

It is noteworthy that the single specimen of N. tonkinensis was captured at the same locality in Cuc Phuong National Park on the same date as the two known females of another new species very similar in appearance but with drastically different genitalia and named in another new genus ( Heppner & Bae 2015).

Figures

FIGURE 8. Nexosa tonkinensis, n. sp., female genitalia, with details a) sterigma, ostium, and basal duct of accessory bursa and ductus seminalis (slide JBH 3126).

FIGURES 1 – 2. Nexosa species in Vietnam. 1. N. hexaphala tamdaoana, n. subsp., holotype male (13.8 mm wingspan). 2. N. tonkinensis, n. sp., holotype female (12.3 mm wingspan).

FIGURES 3 – 6. Nexosa species head close-ups (lateral and dorsal views). 3 – 4. N. hexaphala tamdaoana, n. subsp., male. 5 – 6. N. tonkinensis, n. sp., female.