Was Gordon Robilliard right? Integrative systematics suggests that Dendronotus diversicolor Robilliard, 1970 is a valid species

Canadian Journal of Zoology. 2016. Vol. 0. No. ja.

Ekimova I., Valdés Á., Schepetov D., Chichvarkhin A.

Nudibranch molluscs of the genus Dendronotus Alder and Hancock, 1845 are widely distributed in the Northern Hemisphere. Taxonomic studies on the genus Dendronotus have been problematic due to high variability in colour pattern in many species, as well as in external morphology and anatomy. In the present paper, we studied specimens of Dendronotus from northern Pacific presumably belonging to the species Dendronotus albus MacFarland, 1966. Molecular and morphological data revealed the existence of two distinct species among the material examined: D. albus, which has a wide range from Kamchatka and the Kurile Islands (from where we report this species for the first time) to California in North America, and the pseudo-cryptic species Dendronotus diversicolor Robilliard, 1970, which has been previously considered a junior synonym of D. albus. D. diversicolor occurs from California to British Columbia in sympatry with D. albus. D. albus and D. diversicolor can be clearly distinguished by colour pattern, internal and external morphology and molecular sequence data. Despite some similarities in radular and external morphology between D. albus and D. diversicolor, these two species are phylogenetically distant and belong to different clades within the genus Dendronotus which suggests convergent evolution.

Keywords: evolution, Systematics