Range extension for the region of sympatry between the nudibranchs Hermissenda opalescens and Hermissenda crassicornis in the northeastern Pacific

In the summer of 2016, three students in Marine Ecology armed with curiosity and a love for the ocean started exploring the docks at BMSC and, much to everyone’s surprise, they found something odd – they found a cryptic species of nudibranch that shouldn’t have been there! This simple discovery, which started off as a student project, grew in scope to include researchers from across Canada and California, and was just recently published in the journal FACETS.

This work advances our knowledge of the Hermissenda (Gastropoda, Heterobranchia) pseudocryptic species complex along the Pacific coast of North America, including H. crassicornis (the more northerly species) and H. opalescens (the more southerly species).  We report the unexpected presence of H. opalescens from collections on the West coast of Vancouver Island.  This new evidence substantially revises the northerly range limit for this species, previously reported as northern California, and indicates a substantial region of sympatry with H. crassicornis.  Our analyses also add further detail regarding the morphological differences that can be used to distinguish the two species.  We believe these findings are valuable in two ways: 1) contributing to evidence of northward range shifts in response to either the recent marine “heat wave” in the North Pacific or global climate change, and 2) interpreting potential intraspecific versus interspecific differences in the neurobiology of Hermissenda given the extensive catalogue of previous studies of learning and memory in these animals.

Spearheaded by Russell Wyeth (StFX), this highly collaborative work included BMSC undergraduate students (Emily Merlo (SFU), Kathryn Milligan (UBC), and Nola Sheets (UVic)), BMSC faculty (Chris Neufeld, Tao Eastham), and researchers from the University of Guelph (Dirk Steinke, Paul Hebert) and California State Polytechnic University (Ka’ala Estores-Pacheco, Ángel Valdés)

Link to article.