Comparative geometric morphometrics of male genitalia in Xiphocentron subgenera (Trichoptera: Xiphocentronidae): new species, revision and phylogenetic systematics of the subgenus Sphagocentron

Abstract

Geometric morphometric statistics have been employed to reduce the subjectivity of visual evaluations in taxonomy. Taxonomy in most insect groups relies strongly on male genitalia morphology which is often the structure with most data available, which is also true to caddisfly taxonomy. Here we revise the caddisfly subgenus Xiphocentron (Sphagocentron) adding five new species after 40 years: X. dactylum sp. nov., X. eurybrachium sp. nov., X. tapanti sp. nov., and X. tuxtla sp. nov. Additionally, we describe a new X. (Antillotrichia): X. drepanum sp. nov. from French Guiana and provide new species records of Xiphocentronidae from Bolivia, Costa Rica and Ecuador. We performed exploratory geometric morphometric analysis on the male genitalia’s preanal appendage to characterize the shape differences among the species, and to investigate its utility to classify species to subgenera. In order to infer species relationship and assess if shape congruences are due to phylogenetic signal or convergence data from 100 landmarks and semilandmarks, and 30 discrete characters were used to generate a phylogenetic hypothesis. The morphometry partially supports the subgenera delimitations, but the Antillotrichia subgenus greatly overlapped with other subgenera. The discriminant analysis overall classification correctness was 64%. Some suggested phenotypic groups were due to convergence. According to the preanal appendage morphometry, X. (Antillotrichia) fuscum is a Sphagocentron species. The phylogenetic analysis recovered Sphagocentron as monophyletic, but not Antillotrichia. Sphagocentron subgenus was placed within a clade of several Antillotrichia species, with X. (A.) fuscum as the sister of the other Sphagocentron species, although support values were low.