Phylogeny of the Nasutitermtinae and Revision of the Neotropical Genus Syntermes Holmgren (Isoptera: Termitidae)

Abstract

The Nasutitennitixiae are one of the most diverse subfamilies of termites, with more than 80 genera and 600 known species. Soldiers of most Nasutitermitinae have their heads modified for, chemical defense, with a long frontal tube connected to a reservoir of defensive secretions. These nasute soldiers are capable of squirting noxious substances on enemies and have vestigial mandibles. A group of 13 neotropical genera of Nasutitermitinae, the mandibulate nasutes, have soldiers with functional mandibles and various degrees of development of the frontal tube; they have been considered to represent intermediate stages toward the evolution of the nasute soldier, and would correspond to the basal branches of the Nasutitermitinae. This work investigates the phylogenetic relationships of the mandibulate nasutes. A cladistic analysis based on 35 morphological characters indicates that the traditional phylogenies are incorrect and that the mandibulate nasutes form a monophyletic group in which a long frontal tube evolved independently. The analysis of a fragment of the 16S rRNA gene provides some support for the same conclusion, but with lower resolution. The taxonomy of the genus Syntermes, traditionally considered the most primitive of the Nasutitermitinae, is revised, and 23 species are now recognized. Six species are described as new: S. barbatus, S. cearensis, 5. crassilabrum, S. longiceps, 5, nanus, and 5. tanygnathus; the imagoes of 5. aculeosus, S. chaquimayensis, and S. wheeleri are described for the first time; two species, S. bolivianus and 5. wheeleri, are revalidated; and six new synonyms are proposed: S, hageni (previously treated as a synonym of S. dims) and 5. lighti are junior synonyms of 5. granéis; and S. solidus, S. chaquimayensis parvinasus, 5. emersoni, and 5. robustus are junior synonyms of S. spinosus. A phylogenetic analysis of the species of Syntermes was based on 45 characters indicates that most characters of this genus that have been considered primitive are actually derived. Based on the cladistic analysis of the mandibulate Nasutitermitinae, Cahuallitermes, new genus, is described with two species from tropical North America, C. aduncus, new species, from southern Mexico and C intermedins, new combination, from Belize and Honduras.