Celaenorrhinus galenus

Celaenorrhinus galenus (Fabricius 1793) group

Celaenorrhinus galenus (Fabricius 1793) was originally described from "Indiis" – apparently an error of locality. It is variable through its range from Sierra Leone to Kenya to Malawi, and closer study may reveal more than one species. At present the Kenyan population can be divided into two subspecies: opalinus Butler 1900 (TL ‘Roromo’, [Limuru], Kenya) from the Central Highlands to Western Kenya, and biseriata (Butler 1888) (TL ‘Kilima-njaro’) found from the coast, inland to Kibwezi.

The two subspecies opalinus and biseriata were both originally described as valid species, but Evans (1937) treated them as forms of galenus, and this practice has continued (e.g. Ackery et al. 1995). However, Larsen (1991) recognised opalinus as a subspecies of C. galenus, and Collins & Congdon (1998) did the same for biseriata. Larsen (2005) subsequently referred to biseriata as probably being a valid species without taking any formal action.

Subspecies biseriata is larger than opalinus; the fore wing spots are larger, particularly those in the distal half of space 1B which are joined together, and those in spaces 4 and 5; the large orange spot on the hind wing covering spaces 3–5 is interrupted by a bar across the middle, but is continuous with the orange cilia, at least in spaces 4 and 5. In contrast, ssp. opalinus is smaller; the fore wing spots are smaller, including the two small ones in the distal half of space 1B, of which the lower is separate and displaced basally; the large orange spot of the hind wing is sometimes interrupted in space 3, but never in spaces 4–5 and the orange spot is nearly always separated from the orange cilia in spaces 4 and 5 by a dark bar. I found no significant consistent difference between the early stages of the two, except that the mature caterpillars of biseriata are larger, and the head capsules are significantly larger. Furthermore, the male genitalia show significant and obvious differences, the clasp of biseriata being much larger, and the uncus is different. I have not found the two taxa sympatric anywhere in Kenya, but patches of woodland east and downhill from Nairobi would be worth checking for this possibility. On balance, given the consistent wing marking differences, genitalia differences and caterpillar size differences, the two taxa would seem to be distinct species. However, this does not resolve the relationship of these two taxa to galenus itself. So, without reviewing material from the wider range of galenus, opalinus and biseriata I am reluctant to raise these two subspecies to species status in isolation, not least because the problem is being addressed (M. Libert in prep.) in preparation for T.B. Larsen’s revision of the African Hesperiidae.

Vuattoux (1999) reports rearing three specimens of ssp. galenus on Hypoestes forskaolii (= verticillaris) (Acanthaceae), which as reported below is also a food plant for both opalinus and biseriata. Larsen (2005) attributes a record of Clerodendrum paniculatum (Lamiaceae) to Vuattoux (1999), but this is a misinterpretation of an adult nectaring: “ un autre [adulte] a été capturé sur une inflorescence de Clerodendrum paniculatum Vent. ”. Heath et al. (2002) refer to Hypoestes and Justicia as the food plants of C. galenus galenus, but these may be based on records from other subspecies (or species).

Either opalinus or biseriata seem to be found almost everywhere there is forest left in Kenya, except I have not found either in the coastal forests just above sea level. Kielland (1990) also notes galenus as common from 300 to 2400 m, “in all forested areas of Tanzania, except perhaps coastal forests”. However, this observation was made before biseriata was recognised as a valid subspecies and the description of C. handmani by Collins & Congdon (1998), and hence the records of C. galenus from lower and higher altitudes probably refer to that subspecies and species respectively.