Morphology matters: congruence of morphology and phylogeny in the integrative taxonomy of Clevelandellidae (Ciliophora: Armophorea) with description of six new species

Abstract

Abstract Armophorid ciliates of family Clevelandellidae represent ecologically interesting symbionts of ecologically interesting hosts: wood-eating cockroaches of subfamily Panesthiinae unrelated to the termite/Cryptocercus lineage. Moreover, these protists exhibit a peculiar morphology, with the posteriorization of oral structures being the most striking of their unique characters. Despite that, the family is relatively understudied, with only a handful of morphologically novel species being described since its erection more than 80 years ago. Recently, however, several clevelandellid species were described solely on the basis of molecular characters and it has been suggested that morphology should be abandoned in favour of purely molecular taxonomy. In our study we report on the diversity of Clevelandellidae from the widest host spectrum assessed so far, characterize a majority of previously described Clevelandellidae species, and describe six new Clevelandella species. By applying an integrative taxonomical approach, using molecular and modern morphological methods, we demonstrate the pitfalls of a purely molecular approach and show that morphology still has its place in the taxonomy of Clevelandellidae. Moreover, thanks to a combination of observations of in vivo cells, protargol preparations, and scanning electron microscopy (used for the first time in Clevelandellidae), we were able to clarify morphological uncertainties of previous works and discuss various morphological peculiarities of Clevelandellidae.