Phylogenetic relationships are hypothesized and a revised taxonomy for the Sphecosoma genus group is proposed, based on a cladistic study of adult morphological characters. These moths have a neotropical distribution and are accurate mimics of polybiine wasps. The last complete treatment of the group was by Hampson in 1898. We provide a taxonomic history of genera associated with Sphecosoma.
We examined 61 of the 89 described species in the 14 genera associated with Sphecosoma. These genera included Abnormipterus Orfila, Bombopsyche Hampson, Metamya Travassos, Methysia Butler, Myrmecopsis Newman, Orcynia Walker, Phaeosphecia Hampson, Pleurosoma Orfila, Pompiliodes Hampson, Pompilopsis Hampson, Pseudosphecosoma Strand, Sphecops Orfila, Sphecomimax Bryk, and Sphecosoma Butler. To establish putative outgroups, we examined dissections of 39 species of 37 ctenuchine–euchromiine genera and we selected 13 species in 7 genera. Outgroup genera included Calonotos Hübner, Chrysocale Walker, Horama Hübner, Isanthrene Hübner, Macrocneme Hübner, Metaloba Hampson, and Pseudopompilia Druce. The data set consisted of 52 adult morphological characters (22 binary, 30 multistate, 195 states total) from head, thorax, and abdomen. Characters were traditional and novel (i.e., microtymbals, abdominal apophyses) and were unrelated to wasp mimicry. Maximum parsimony (MP) was performed.
The final analyses yielded 24 most parsimonious trees in two islands (L = 353, CI = 0.42, RI = 0.64). The tree islands differ in the placement of Orcynia and Pseudopompilia. Our revised classification includes six genera and two species groups that reflect clades supported by both islands. The following genera are included in our revised concept of the Sphecosoma genus group: Horama, Methysia, Myrmecopsis, Pleurosoma, Pseudopompilia, and Sphecosoma. Within Sphecosoma, we recognize two species groups, the S. cognatum species group and the S. aliena species group. We remove Orcynia from the Sphecosoma genus group.
We provide redescriptions and diagnoses of the six genera and two species groups along with illustrations of relevant structures. Our revised taxonomy results in six new generic synonyms, 22 new combinations and one new species name (Sphecosoma donahuei Simmons), summarized in a species checklist.
