the genus Abraxas in Hong Kong
There are at least four species of Abraxas Leach, 1815 (Geometridae, Ennominae, Abraxini) in Hong Kong, all probably belonging to the subgenus Calospilos Hübner, 1825.
The adult moths are typical broadly rounded-winged, slender bodied geometrid moths, with white or pale cream wings, upon which pale to dark grey markings are usually present along the outer edges, as well as grey spotting medially and near the tornus (anal angle), the latter spot often comprising a smattering of black and orange scales plus a metallic pale blue streak. The body is orange-yellow, with chequered or reticulate black patterning. As such, the genus is readily identifiable – there is no similar looking moth genus in Hong Kong.
Now the tough part.
The subgenus Calospilos is species rich, but most of the species look roughly the same externally, and almost all have a high degree of variation in the extent of grey markings. The most well known species of the subgenus is the Clouded Magpie, a.k.a. Abraxas sylvata (=Phalaena ulmata Fabricius, 1775. Systema entomologiae : 632, a junior synonym of Phalaena sylvata Scopoli, 1763, Ent. Carniolica: 220) from the Palaearctic region, extending throughout Europe to western Asia, and from Japan as the subspecies microtate Wehrli, 1931. A. sylvata is designated the type species of the subgenus, and thus regarded as representative of the subgenus. A. sylvata is not known from nearby Taiwan, although there are 17 other Abraxas species recorded there, 11 of which are also in the subgenus Calospilos.
What about Hong Kong?
Well, adult moths of three of the four species here are pretty much the same in appearance as each other and as sylvata. We know (because the voucher material has been dissected) there are Abraxas illuminata Warren, 1894 and A. amicula Wehrli, 1935 here. We also know (because it’s dna match the one Hong Kong Abraxas voucher tested) A. tenuisuffusa Inoue, 1984 is here. On iNaturalist, any one of these three species can be identified as Complex Abraxas amicula-illuminata. In the field (and hence from a live habitus photo) it is not possible to id the observation to species rank.
The 4th and (so far) last species in the group from Hong Kong is not yet identified. It has much less grey marking, and a more extensive tornal patch on both the fore and hind wings.
The Larvae…..
Fortunately, the larvae of two of these species are known:
Abraxas illuminata larvae are black, abdominal segments 2 to 5 have one large and two very small white blotches on the side of the abdomen, in the full grown larva . . .
(photo by Andrew Hardacre on iNaturalist)
Abraxas amicula larvae are striped longitudinally . . .
(photo by Andrew Hardacre on iNaturalist)
However, there is a third type of patterning, quite similar to A. illuminata – the spots on sections A2 to A5 are replaced by white “uneven” banding . . .
Could this be a younger instar of A. illuminata? or is it A. tenuisuffusa, or even the unidentified Abraxas species above, or perhaps yet another species not yet formally documented from Hong Kong????
(photo by Kit Law on iNaturalist)
Well there you have it – that’s as much non-technical info that there is for this genus in Hong Kong. If you want to find out more, like the larval hosts, or associating unidentified larvae with the adults, then get out into the field, seek, observe, question and rear.
For more technical stuff, seek out the late Prof. Hiroshi Inoue’s 1984 paper on the genus:
Inoue, H., 1984. The genus Abraxas of Taiwan. Bulletin of the Faculty of Domestic Sciences, Otsuma Women’s University 20: 93-128.
There is also now available online the Moths of Nepal series, of which Abraxas is covered in part 4, plates 120 and 121 . . . dissected specimens of illuminata and amicula are illustrated therein.
Hong Kong Moths 