Sphingidae of the Eastern Palaearctic

HYLOICUS FORMOSANA (Riotte, 1970)

Male Hyloicus formosana, Jenai, Taiwan. Photo: © NHMUK

TAXONOMY

Sphinx formosana Riotte, 1970, Ent. Z., Frankf. a.M. 80: 14. Type locality: Central Formosa [Taiwan, Nantou Hsien], Wushai [Jenai].

ADULT DESCRIPTION AND VARIATION

Wingspan: 68--75mm. A close relative of Hyloicus crassistriga Rothschild & Jordan, 1903 from Japan, but wings much narrower, forewing with apex slightly falcate, hindwing with apex pointed. Forewings with a general dusting of pale grey scales over the upperside; however, in collections these grey scales fade to brown with age.

Male genitalia similar to those of Hyloicus crassistriga, but valve more robust; harpe with outer margin dentate at dorsal half, ventral edge more produced; saccus longer; sacculus characteristically with a strongly toothed outer edge; phallus sigmoidal, ending in a curved point and with a subapical lateral convexity.

Adult Hyloicus formosana, Alishan Forest Recreation Area, Alishan Township, Chiayi Hsien, Taiwan, 2178m, 4.vii.2018. Photo: © Lin MeiHui, courtesy Taiwan Moth Information Center.

ADULT BIOLOGY

A montane species, occurring above 2000m altitude.

FLIGHT-TIME

Taiwan: vi (Nantou Hsien; Taichung Hsien); 2.vii (Yilan Hsien); 4.vii.2018 (Chiayi Hsien).

EARLY STAGES

OVUM: Unknown.

LARVA: Body apple-green, with three longitudinal white lines per side, with the ventro-lateral partially broken up into a line of 'blobs'. The dorso-lateral and ventro-lateral edged with black/grey, the dorsal pair bordering a dark mahogany-brown dorsal band. The green areas with fine grey-white tubercles; the brown anal flap/claspers with fine black tubercles. First thoracic segment edged with blue frontad. Horn black, thin, slightly curved and tubercled. Head oval, light mahogany brown with yellow cheek stripes, which are bordered in front with darker brown. Very similar to that of the closely related Hyloicus centrosinaria (Kitching & Jin, 1998) from Sichuan, China.

Full-grown larva of Hyloicus formosana, Malun Shan, Heping District, Taichung Hsien, Taiwan, 2080m, 12.viii.2018. Photo: © Grace Yeh, courtesy Taiwan Moth Information Center.

PUPA: Unknown.

Larval hostplants. Unknown.

PARASITOIDS

Unknown.

LOCAL DISTRIBUTION

Taiwan: Nantou Hsien (Jenai); Yilan Hsien (Taipingshan; Datong township, 2621m); Taichung Hsien (Tashiiehshan, Anmashan, 2230m; Heping District, Malun Shan, 2080m; Heping District, Qika Villa, 2524m); Chiayi Hsien (Alishan Township, Alishan Forest Recreation Area, 2178m).

GLOBAL DISTRIBUTION

Endemic to the northern central mountains of Taiwan.

Part of the relict eastern Palaearctic fauna of montane Taiwan. Closely related species are found in Japan (Hyloicus crassistriga Rothschild & Jordan, 1903) and southwest mainland China (Hyloicus centrosinaria (Kitching & Jin, 1998)).

Global distribution of Hyloicus formosana. Map: © NHMUK.

BIOGEOGRAPHICAL AFFILIATION

Holarctic; eastern Palaearctic region. Pleistocene refuge: Monocentric -- Taiwan refugium.

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