Range extension for the region of sympatry between the nudibranchsHermissenda opalescensandHermissenda crassicornisin the northeastern Pacific

Abstract

The mollusc nudibranch genus Hermissenda Bergh, 1879 was recently discovered to include three pseudocryptic species, dividing a single species H. crassicornis (sensu lato) into H. crassicornis Escholtz, 1831, H. opalescens J.G. Cooper, 1863, and H. emurai Baba, 1937. The species were distinguished by both genetic and morphological evidence, and the distribution of sampled animals suggested the three species had mostly distinct geographical ranges. Here, we report the presence of both H. crassicornis and H. opalescens in Barkley and Clayoquot Sounds, British Columbia, Canada, based on diagnostic characters and molecular data congruent with the differences described for these two species. This result extends the region of sympatry for the two species from northern California, USA, to, at least, Vancouver Island, British Columbia in 2016. Depending on how long this overlap has occurred, the possible northward expansion of H. opalescens would have implications for understanding the effects of short-or long-term environmental changes in ocean temperatures as well as complicating the interpretation of past neurobiological studies of H. crassicornis (sensu lato).

Why didn’t the nudibranch cross the ocean? Understanding biogeographic and evolutionary relationships ofHermissenda(Nudibranchia: Myrrhinidae) Bergh, 1878

“…Our GBIF map, including iNaturalist data, agrees with the Merlo et al (2018) (Harrigan & Alkon, 1978). According to that rate, the 2.5-cm Hermissenda on vessel BF-356, would be approximately 72 days post-hatching.…”

“…Our GBIF map, including iNaturalist data, agrees with the Merlo et al (2018) range extension of Hermissenda opalescens north to Vancouver Island. Our map also shows a more southern extension of H. crassicornis than previously understood, extending the area of range overlap between H. opalescens and H. crassicornis .…”

“…3). Previous work has made haplotype networks for each Hermissenda species separately, but none have shown all three together (Lindsay and Valdés, 2016; Merlo et al, 2018). The haplotype network we produced shows three distinct groups, with our samples clustering according to species groups (Fig.…”

“…Lindsay and Valdés (2016) reported that the area of overlap between the two species to be between Bodega Bay and Point Reyes in California, with H. crassicornis extending as far north as Alaska and H. opalescens ranging south to the tip of Baja California. Additional observational data in the northeastern Pacific then extended the range of H. opalescens north to Vancouver Island (Merlo et al, 2018). An increased area of sympatry could also mean increased opportunities for hybridization, as has been shown in both marine and terrestrial organisms (Arce-Valdés and Sánchez-Guillén, 2022; Garroway et al, 2009; Hobbs et al, 2018).…”

Looking at the Nudibranch Family Myrrhinidae (Gastropoda, Heterobranchia) from a Mitochondrial ‘2D Folding Structure’ Point of View

“…The family Myrrhinidae includes charismatic species, which is distributed worldwide and interesting from different points of view. Hermissenda crassicornis (Eschscholtz, 1831) is a model organism used in various research fields, such as neurology, ecology, ethology, pharmacology and toxicology [ 33 , 34 , 35 , 36 , 37 , 38 , 39 ]. Species belonging to the genus Phyllodesmium are a group of highly specialised nudibranchs with sophisticated species-specific mechanisms of mimicry with external body features indistinguishable from their cnidarian hosts and are animal models for several studies on chemistry and cell biology or focused on the mechanisms of the symbiotic relationship with the zooxanthellae living in their digestive gland cells [ 40 , 41 , 42 ].…”