The phylogeography and social structure of the narrow endemic velvet worm species Opisthopatus amaxhosa were investigated by conducting fine‐scale sampling in its distribution range in the Eastern Cape province of South Africa. In addition, and as part of larger grant on forest biodiversity, Opisthopatus specimens sampled at localities not included during a recent evaluation of the genus were included in a new phylogeny. A total of 89 specimens from 18 sample localities were collected at three forest patches for O. amaxhosa samples, while an additional six Opisthopatus sample localities were included. For O. amaxhosa, we sequenced the COI locus for all specimens, while a subset of specimens was sequenced for two nuclear loci, 18S rRNA and the fushi tarazu intron (FTz). Phylogenetic analyses using maximum likelihood and Bayesian inferences of the latter species revealed the presence of two highly divergent clades, characterised by marked uncorrected sequence divergence values. In addition, these two clades did not share any maternal haplotypes, were characterised by high FST values and fixed nuclear difference for the 18S rRNA locus, while the FTz intron was genetically invariant. Furthermore, the application of scanning electron microscopy between the two genetically divergent clades also revealed the presence of fixed ventral and dorsal scale numbers. Collectively, this provides evidence for a novel species that is present at a fine scale. Divergence time estimations suggest that the two clades diverged during the late and early Pleistocene with climatic cycling potentially causal to the fragmentation. The social structure was male‐biased, and samples from the same logs were not always genetically identical. At the broader scale, the inclusion of new specimens within Opisthopatus revealed no novel lineages. Fine‐scale sampling appears more important to detect alpha taxonomic diversity compared to broadscale sampling.
Aaron Barnes, Savel R. Daniels