Hesperiinae Latreille 1809

HESPERIINAE Latreille, 1809

Hesperiinae is a long recognised subfamily of Hesperiidae, although it is only since Higgins (1975) that Heteropterinae has been separated from Hesperiinae and recognised as a subfamily. Warren et al. (2008, 2009) find morphological and molecular evidence strongly supporting Hesperiinae as a monophyletic subfamily. However, the tribal classification of Hesperiinae is much less clear, and large groups of genera are treated as incertae sedis in their analysis. For the Afrotropical Hesperiinae, Ampittia Moore is now placed in Aeromachini Tutt and Brusa Evans, Zenonia Evans, Gegenes Hübner, Parnara Moore, Borbo Evans, and Pelopidas Walker are placed in Baorini Doherty but all other African genera are incertae sedis. The Hesperiinae tribes Taractrocerini Voss, Thymelicini Tutt, Calpodini Clark, Anthoptini A. Warren, Moncini A. Warren and Hesperiini Latreille are not represented in Africa.

At this time we have not reared or located food plant records for the following Hesperiinae genera found in Africa: Brusa, Fulda Evans, Galerga Mabille, Gyrogra Lindsey & Miller, Lepella Evans, Malaza Evans, Miraja Evans, Mopala Evans. Osphantes Holland, Paracleros Berger, Prosopalpus Holland and several new genera which T.B. Larsen (pers. comm.) will describe.

Traditionally, Hesperiinae are considered to use monocotyledons as food plant plants, and in Europe they only feed on grasses (Poaceae). Thus, one of the questions in MJWC’s mind when he started rearing Hesperiinae was why are there so many species—how do they avoid competitive displacement if they all feed on grasses? In fact many genera do not feed on grasses, but feed on other families of monocotyledons, such as Arecaceae, Asparagaceae (especially Dracaena), Costaceae, Cyperaceae, Marantaceae, and Zingiberaceae. Furthermore, especially in Africa, a significant number of genera feed on dicotyledonous plants, and it seems clear that at least two, perhaps more, groups of genera have evolved from an ancestor that made the food plant switch from monocotyledons back to dicotyledons. These groups and other Hesperiinae will be treated in future papers, and in this contribution, we treat the only two tribes of Hesperiinae that are recognised by Warren et al. (2009) and include African species: Aeromachini and Baorini.

The two tribes treated here seem to be almost entirely grass (Poaceae) feeders—at least in Africa. However, even amongst Poaceae feeders, there may be specialisation. Sometimes this is obvious, e.g. bamboo feeders, but other times it is less obvious, e.g. on broad leaved grasses such as Setaria, or on fragile, narrow leaved grasses such as Cynodon. Furthermore, entomologists tend to identify food plants as just “grass”, especially when it is a nonflowering grass, and the authors have had to resort to this sometimes for this work. Today, this could be addressed by collecting samples in silica gel or using FTA® paper (Whatman, Inc.) for subsequent DNA-based identification, even for non-flowering food plants (see discussion of methods and uses in Gaskin et al. (2011) in the context of weed biological control). There still seem to be many Hesperiinae species that can be found on a wide variety of grasses—what D.H. Janzen (pers. comm.) characterised as ‘lawnmowers’, when we discussed this issue, some years ago. It may be that many Baorini fit this description, although in all cases more field work is needed to clarify this. There may also be geographical, ecological or temporal differences in food plant utilisation, or preferred food plants, which will only become apparent as more detailed location-specific information becomes available. For example a particular food plant may be routinely used in one part of a skipper’s range but only when other food plants are unsuitable in another part. A further complication is that in captivity, caterpillars will often accept several different grasses—which makes rearing them easier, but there is the risk of food plants accepted in captivity entering the literature as natural food plants—which further collections may show them to be, but the original record is an artefact of captivity until confirmed from field observations and collections (Cock 2010a, b). Because many grass-feeders will accept a variety of grasses in captivity, this can be used to good effect, by rearing them from ova obtained from wild-caught females, and in this way the early stages can be documented, even if the natural food plant grasses are unknown (Dethier 1939).