Date of Award

Winter 2017

Project Type


Program or Major

Biological Sciences

Degree Name

Master of Science

First Advisor

Larry G Harris

Second Advisor

Terrence M Gosliner

Third Advisor

Alan M Kuzirian


Until recently, the nudibranch genus Tenellia (Nudibranchia: Fionidae) was thought to include a single or group of species restricted to temperate estuarine waters. Given the addition of numerous other species from recent studies, the genus now encompasses species from polar, temperate, and tropical oceans from oceanic to estuarine salinities. One such fionid, Tenellia adspersa, is found in temperate estuarine waters globally and its presence is ecologically important as its congeners are capable of decimating colonies of their hydroid prey within a single generation (approx. 20-60 days). The literature is historically vague and conflicted on the morphology, taxonomy, and geographic distribution of the various estuarine species of Tenellia, that includes: T. adspersa (Nordmann, 1844), T. fuscata (Gould, 1870), T. pallida (Alder & Hancock, 1842), T. mediterannea (Costa, 1866), T. ventilabrum (Dalyell, 1853), and Embletonia fuscata (Chambers, 1934). While Tenellia adspersa has been affirmed by several authors, others have proposed the taxon is comprised of at least two species.

This study represents an extensive sampling of T. adspersa, and the first to incorporate more than two genetic sequences within a phylogenetic study. Specimens of T. adspersa were collected from global localities to produce a more current and detailed phylogenetic analysis and systematic review of the genus. Ninety-five specimens were collected from Eastern Pacific, Western Atlantic, and Eastern Atlantic localities. From these, forty-five specimens were sequenced for the genes cytochrome c oxidase subunit I (CO1), 16S ribosomal RNA, or the histone protein H3. While morphological analyses were informative but not definitive in separating species, molecular analyses revealed a species complex; with multiple groups. Species delimitation by the Automatic Barcode Gap Discovery tool, coupled with a TCS haplotype network analysis and Maximum Likelihood were conducted. They revealed several distinct clades within the T. adspersa species complex (TASC). Eleven new sequences of T. adspersa fit into the larger Fionidae phylogeny, in addition to two previous specimens from past studies. There is 100% support for the monophyletic status of a T. adspersa species complex. Equally supported are four distinct clades, two primary and two secondary, within the species complex based upon geographic localities. These molecular analyses elucidate both natural distributions and introductions for this cryptic nudibranch.