Celaenorrhinus Hübner 1819

COCK, MATTHEW J. W. & CONGDON, T. COLIN E., 2011, Observations on the biology of Afrotropical Hesperiidae (Lepidoptera) principally from Kenya. Part 3. Pyrginae: Celaenorrhinini, Zootaxa 3033 (1), pp. 1-67 : 5-6

Celaenorrhinus Hübner 1819 (in Hübner 1816–[1826])

This genus is unique amongst Hesperiidae in that representatives are found in tropical America, Africa and Asia. The type species of the genus, C. eligius (Stoll) , is a South American species. De Jong (1982) made a study of the scent-producing organs of male Celaenorrhinus spp. from all three continents. Having moved two species into the genus, he was able to delimit it based on the unique character of abdominal pouches with scent hairs, which he concludes evolved only once, and was subsequently lost in some species, including those of the African mainland. Warren et al. (2009) included only two species of Celaenorrhinus in their study, C. eligius and the African C. leona Berger and found that these two species were not monophyletic in their cladogram, although they felt two species insufficient to draw any conclusions about the group’s status.

As Warren et al. (2009) point out, adults of a few American Celaenorrhinus spp. are crepuscular and/or nocturnal, and roost diurnally in caves (e.g. Bailey 1880; DeVries et al. 1987) or under culverts, but most Celaenorrhinini are active during the day ( Larsen 2005), and crepuscular behaviour has not been reported for African Celaenorrhinus spp. , although there are observations of roosting by day for Sarangesa spp. (below).

All Neotropical food plant records ( Beccaloni et al. 2008), including my own in Trinidad (Cock & Alston- Smith 1990), are from Acanthaceae , apart from one record of C. stola Evans from Rhynchosia longeracemosa (= Dolicholus longeracemosa ) ( Fabaceae ) in Mexico ( Kendall & McGuire 1975). The caterpillars of the two Trinidad species, C. eligius eligius and C. bifurcus Bell are similar to those of C. proxima (Mabille) and related species, treated below (M.J.W. Cock unpublished). The Asian species of Celaenorrhinus have a more varied range of food

Adults always rest with their wings held flat, and when not feeding usually rest underneath leaves, effectively, and confusingly appearing to disappear when they settle. They feed readily at flowers, when they are easily caught. I have not observed them to feed at water, urine or faeces, but Larsen (1991) records an observation of C. bettoni Butler feeding at faeces, and Kielland (1990) observed C. uluguru Kielland attracted to mud on the road.

The caterpillars are all quite similar, and not readily used to distinguish species. There are also several pairs or groups of closely related species with very similar caterpillars; hence, all caterpillars, but especially those from new host plants, should be reared from sites such as Kakamega Forest where species of unknown biology are to be found. Although all caterpillars appear to have smooth bodies without setae, microscopic examination at x40 shows that all have scattered very short, pale, stalked, stellate setae.

Pupae of the African species which have been reared are either green or brown. Most are bare, with no white waxy covering, but as noted below, this is not the case in C. mokeezi (Wallengren) . Some have one or three projections on the head, others none. All have a well developed proboscis sheath, sometimes extending well beyond the tip of the cremaster. Based on the limited number of Celaenorrhinus spp. that we have reared from Africa, we recognise two sections differentiated on the pupa. The first section comprises those species with a brown pupa with three upturned projections on the head, one frontal, and one on each eye. The second section comprises those species with a green pupa, at most a slight broad frontal protuberance and a proboscis sheath extending significantly beyond the cremaster. It may be that when more species have been reared these two sections will not be so clear cut, but for the moment they provide a useful classification hypothesis.

Aurivillius (1925) gives a brief description of the caterpillar and pupa of C. mokeezi , which he reports to feed on a Justicia sp. Pinhey (1965) gives Isoglossa and Justicia as food plants of C. mokeezi . Clark (in Dickson & Kroon 1978, plate 3) illustrates the life history of C. mokeezi mokeezi in detail. Dickson & Kroon (1978) and Pringle et al. (1994) give the food plant of C. mokeezi mokeezi as Isoglossa woodii (Acanthaceae) in South Africa, but Henning et al. (1997) attribute this food plant to C. mokeezi separata (Strand) . The green pupa of C. mokeezi differs from the two groups that we have recognised, being generally covered with white powder, and having just a short blunt frontal projection (Clark in Dickson & Kroon 1978; Henning et al. 1997), and provides the basis for a third pupal group.