Revision, phylogeny and historical biogeography of the genus Apodrosus Marshall, 1922 (Coleoptera: Curculionidae: Entiminae)

Abstract

Abstract The Caribbean weevil genus Apodrosus Marshall, 1922 is revised, including a redescription of A. argentatus Wolcott, 1924 and A. wolcotti Marshall, 1922 and description of 11 new species: A. adustus, sp.n. (Bahamas), A. andersoni, sp.n. (Dominican Republic), A. artus, sp.n. (Dominican Republic), A. earinusparsus, sp.n. (Dominican Republic), A. empherefasciatus, sp.n. (Bahamas), A. epipolevatus, sp.n. (Puerto Rico), A. eximius, sp.n. (Dominican Republic), A. mammuthus, sp.n. (Mona Island, Turks and Caicos Islands), A. quisqueyanus, sp.n. (Dominican Republic), A. stenoculus, sp.n. (Dominican Republic) and A. viridium, sp.n. (Dominican Republic). A key to the species and illustrations of external and internal structures are provided. Apodrosus is characterized as a monophyletic group by two unreversed synapomorphies – i.e., the presence of a median fovea on the apex of abdominal sternum VII and a J- or Y-shaped spermatheca – and is furthermore differentiated from related taxa by a unique combination of diagnostic features including the presence of premucro, a complete tegminal plate in males, the absence of longitudinal sclerites in the genital chamber of females, and an apical projection on the spermathecal cornu. A phylogenetic reconstruction of 20 taxa (7 outgroup, 13 ingroup) and 25 morphological characters yielded a single most parsimonious cladogram (L=61 steps, CI=42, RI=74) with the ingroup topology (A. artus, (A. andersoni, (A. earinusparsus, (A. epipolevatus, A. wolcotti)))), (A. eximius, ((A. argentatus, A. mammuthus), (A. viridium, (A. stenoculus, (A. quisqueyanus, (A. adustus, A. empherefasciatus)))))). The phylogeny indicates that Anypotactus bicaudatus Champion (Anypotactini Champion) is the sister group to Apodrosus, thereby calling into question the traditional tribal placement of this genus in the Polydrusini. The host plant associations of most species remain uncertain. A reconstruction of the historical biogeography of Apodrosus suggests that post-GAARlandia (Greater Antillean+Aves Ridges land span) vicariance was an important factor in the diversification of the higher-elevation inhabiting A. artus-A. wolcotti clade. Conversely, the species richness of the lower-elevation inhabiting A. eximius-A. empherefasciatus clade is most plausibly explained through a series of independent and likely more recent colonization events from the ancestral source area of southwestern Hispaniola to several smaller western Caribbean islands, or – in the case of Hispaniola – within-island areas of endemism.