Two recent studies have suggested that divergent mitochondrial lineages may be present within spirostreptid
genera such as Bicoxidens Attems, 1928. Bicoxidens, similar to many other endemic soil invertebrates, exhibits low
dispersal capabilities and strict microclimate habitat preferences, attributes that often lead to geographic isolation.
Given that prolonged geographic isolation often lays the foundation for population genetic differentiation, genetic
divergence and possibly speciation, there was good reason to suspect that Bicoxidens may consist of several
distinct lineages. On this basis, the mitochondrial cytochrome c oxidase subunit 1 (COI) was used to reconstruct
the phylogeny of Bicoxidens and reveal divergent lineages within the genus. Maximum likelihood and Bayesian
inference analyses recovered a paraphyletic Bicoxidens phylogram with divergent lineages present in three
species – B. friendi, B. flavicollis and B. brincki – suggesting high genetic diversity within the genus. Bayesian
genetic cluster analyses suggested the presence of multiple distinct mitochondrial lineages within the genus
with four identified in B. flavicollis alone. It was therefore concluded that the divergent lineages observed among
Bicoxidens populations may suggest the presence of hidden species.
