Taxonomy | Geometridae | Geometrinae | genus Berta

There are three Berta species found in Hong Kong, all confirmed by dissection and, for two species, rearing.
They are B. chrysolineata; B. rugosivalva & B. zygophyxia.

Whilst preparing the genus write up for the forthcoming Illustrated Guide to the Moths of Hong Kong, I have been head scratching a lot to try and figure out if it is possible to id these three species in the field. Looking at all the posts on iNat from Hong Kong, plus conflicting literature (Moths of Borneo, Fauna Sinica Insecta, Moths of Wutongshan, plus various websites covering the Oriental region), I was none the wiser, and getting a few more white hairs. Time to reach out to others and see what gives. So an email to Sir Anthony Galsworthy, who described B. rugosivalva, and to Mark Sterling, who has faced this dilemma by wielding the dissecting gear, resulted in confirmation that field id is not a realistic proposition. Chop Chop time if one wants an id to species rank.

Consequently, for Hong Kong observations of any Berta individual, no matter how different it might look, I have created the iNat taxon complex for this group - https://www.inaturalist.org/taxa/960018-Berta-chrysolineata-zygophyxia-rugosivalva
All Hong Kong observations, unless backed by dissection or rearing from larva found on a known host (chrysolineata on lychee; rugosivalva on Castanopsis and zygophyxia on Terminalia and Combretaceae) should be identified to this species complex, please.

Elsewhere in the Oriental region there are other species to consider, in particular B. digitijuxta, B. annulifera, so this complex created for iNat is probably applicable to Hong Kong only.

Posted on October 30, 2019 01:05 PM by hkmoths