Phylogenetic placement of the monotypic genus Holopodostreptus Carl, 1913 and notes on the systematics of Pseudonannolenidae (Spirostreptida: Cambalidea)

The genus Holopodostreptus Carl, 1913 is a poorly known monotypic genus endemic to Ecuador. It differs from most other Pseudonannolenidae by a set of characteristics of the gnathochilarium and gonopods. Herein, we provide descriptive notes of males of H. braueri Carl, 1913 based on recently collected material. Females of the species are described for the first time, and images of the vulvae are provided. In addition, we attempt for the first time to place Holopodostreptus in a phylogenetic context. With a total of 14 taxa and 41 morphological characters, and under implied weighting (k = 6), a single most-parsimonious tree is recovered (total fit = 35.86). The genus is recovered as sister-group of Physiostreptus Silvestri, 1903. The clade Holopodostreptus + Physiostreptus is supported by one synapomorphy (absence of setae on the prefemoral process of leg-pair 1 in males) and one homoplastic transformation (narrow telopodite). Based on the phylogenetic results, notes on the subfamilies Pseudonannoleninae, Cambalomminae and Physiostreptinae and a key for all pseudonannolenid genera are provided.