Facelinidae, Bergh, 1889

Goddard, Jeffrey H. R., Treneman, Nancy, Prestholdt, Tara, Hoover, Craig, Green, Brenna, Pence, William E., Mason, Douglas E., Dobry, Phillip, Sones, Jacqueline L., Sanford, Eric, Agarwal, Robin, McDonald, Gary R., Johnson, Rebecca F. & Gosliner, Terrence M., 2018, Heterobranch Sea Slug Range Shifts in the Northeast Pacific Ocean associated with the 2015 - 16 El Niño, Proceedings of the California Academy of Sciences 65 (3), pp. 107-131 : 116-118

Facelinidae

Hermissenda opalescens (Cooper, 1863) . Yellow Bank, Clayoquot Sound, Vancouver Island, British Columbia, 24 specimens, 15 July 2016 ( Merlo et al. 2018) to Baja California Sur ( Angulo-Campillo 2005); northern Gulf of California, Mexico (Farmer and Collier, 1963; Keen 1971).

Previous northernmost locality: Charleston, Oregon ( Goddard 1984 [as H. crassicornis , form lacking bluish-white stripe on cerata; see remarks below])

Additional northern localities: 7 localities in Barkley Sound, Vancouver Island, British Columbia, summer 2016 ( Merlo et al. 2018), Cape Flattery, Washington (Chibahdehl Rocks, Box Canyon, Steve’s Cave), August 2015 ( Fig. 2D ) (K. Fletcher, personal communication with images to JG, 26 April 2016), Haystack Rock, Cannon Beach ( Cullin 2017), Oceanside Beach State Park (observed by TP, 24 April 2016), Otter Crest (observed by TP, June to July 2016), Seal Rock (observed by TP, May to July 2016), Strawberry Hill (observed by TP, April to July 2016 and JG, 4 June 2016; for image see <http://www.inaturalist.org/observations/3527960>), Bob Creek (observed by TP, 7 May and 5 July 2016). Additional records of H. opalescens from Oregon in 2016 and 2017 are available on iNaturalist (<http://www.inaturalist.org/taxa/494603-Hermissenda-opalescens>).

Remarks: Lindsay and Valdés (2016) reinstated H. opalescens as distinct from H. crassicornis (Eschscholtz, 1831) and showed that externally H. opalescens can be distinguished in the Northeast Pacific Ocean from H. crassicornis by the lack of white stripes on the cerata of the former. The two color forms have long been recognized in field guides to nudibranchs from the northeastern Pacific Ocean (e.g., Behrens 1980; McDonald and Nybakken 1980). Lindsay and Valdés (2016, pp. 7 and 8) described the range of H. opalescens as extending from “the Sea of Cortez through Oregon,” but in their conclusions described H. opalescens as ranging north only to Bodega Bay, apparently using a more conservative standard based solely on specimens they sequenced. They then stated that H. crassicornis and H. opalescens overlap in range “between Point Reyes and Bodega Bay,” a distance of only a few km. However, based on the presence or absence of the ceratal stripes, images by Bruce Wight available on the Sea Slug Forum <http://www.seaslugforum. net/showall/hermcras> show that H. crassicornis has been known since at least 2000 from as far south as San Miguel Island, California. Further, Goddard (1984, 1987, 1990), citing Behrens (1980), noted directly or indirectly the presence of non-striped Hermissenda (what we now know to be H. opalescens ) at Charleston, Cape Arago, and Humbug Mountain, Oregon, and Punta Gorda in northern California. He found few H. opalescens relative to the numbers of H. crassicornis at these sites, and their occurrence was probably associated with the El Niño events of 1982-83 and 1986-88 (for images see <https://www.inaturalist.org/observations/12907271>, <https://www. inaturalist.org/observations/12771009>). Hermissenda opalescens has therefore ranged to at least southern Oregon in the past, and H. crassicornis to at least the edge of the Southern California Bight, both likely as ephemeral range shifts driven by opposite phases of the El Niño Southern Oscillation (ENSO).

Hermosita hakunamatata (Ortea, Caballer and Espinosa, 2003) . Punta Entrada, Isla Magdalena, Bahía Magdalena, Baja California Sur, Mexico, 3 specimens, with egg masses, on hydroid Solanderia , 2-5 m depth, 1 September 2015 ( Fig. 3A ) (observed by CH; also see Bertsch and Aguilar Rosas 2016) to Panama ( Hermosillo 2004 [as Phestilla hakunamatata ]).

Previous northernmost locality: Isla Isabella, Nayarit, Mexico ( Hermosillo 2004).

Remarks: The specimens from Bahía Magdelena are the first record of H. hakunamatata from the Baja California peninsula. It was not recorded by Angulo-Campillo (2005) during his four year survey of opisthobranchs from Baja California Sur, including Bahía Magdelena.

Noumeaella rubrofasciata Gosliner, 1991 . Outer Pinnacles, Carmel Bay , California, 1 specimen, 43 m depth, 4 March 2017 (C. Bauder, personal communication to JG, 5 March 2017; Baud- er 2017) to Panama ( Hermosillo 2004).

Previous northernmost locality: Malibu, California ( Goddard et al. 2016).

Additional northern localities: Anacapa Island, California, 1 specimen, 12 m depth, north side of East Anacapa Is. , 10 February 2018 ( Klug 2018) .

Phidiana hilton i (O’Donoghue, 1927). Pinnacle Rock, Bodega Bay , Sonoma Co., California, 7 specimens, low rocky intertidal, 25 November 2015 ( Sones 2015) to Cedros Island, Baja California, Mexico (Farmer and Collier 1963) .

Previous northernmost locality: Palomarin, Marin Co., California (WP and DM, personal observations, January 2011); Duxbury Reef ( Behrens 2004; and see Goddard et al. 2011).

Additional northern localities: Dillon Beach , Marin Co., California, low rocky intertidal, April 2014 – December 2017 ( Thompson, 2017), and 8 specimens, 30 April 2017 ( Fig. 3B ) (observed by WP, DM, PD) .

Remarks: P. hiltoni was first sighted in Bodega Bay at Pinnacle Rock in 2015, and 5 individuals were recorded during a survey on 4 December 2017 (JS and ES, personal observations). Thompson (2017) also recorded specimens from Dillon Beach, just 7 km south, in May, June, July, and December 2016, as well as in March, May, July, and August 2017, also indicating the persistence of this species in Bodega Bay following the initial sighting reported in 2015. Goddard et al. (2011, Appendix) compiled historical records of heterobranchs from Marin and Sonoma counties, which provide robust evidence for the historical absence of P. hiltoni in the region. Additional significant records can be extracted from Steinberg (1963) and Marcus (1961), with many of those records originating from the old Pacific Marine Station at Dillon Beach. Together, all of these sources document the occurrence from the 1940s through 1970s of nearly 50 species of heterobranchs from the outer coast of northern Marin and Sonoma counties, and Phidiana hiltoni is not among them.

Figures

Figure 3. Nudibranch sea slugs found at new northern localities in the Northeastern Pacific Ocean, 2015–2017. A Hermosita hakunamatata, La Bocana, Bahía de Magdalena, Baja California Sur, Mexico, 1 September 2015. Image by CH. B Phidiana hiltoni, Dillon Beach, California, 30 April 2017. Image by DM. C Taringa aivica, Mission Bay, San Diego, California, 14 June 2018. Image by CH. D Diaphoreolis lagunae, Whiskey Creek, Curry Co., Oregon, 19 May 2017 (grid squares 2 mm on a side). Image by NT.

FIGURE 2. Nudibranch sea slugs found at new northern localities in the Northeastern Pacific Ocean, 2015–2017. A Doris cf. pickensi, Morro Bay, California, 25 May 2016. Image by CH. B Doriopsilla albopunctata, Whiskey Creek, Curry Co., Oregon, 19 May 2017. Image by NT. C Doriopsilla fulva, Netarts Bay, Oregon, 16 July 2016. Image by Todd Cliff. D Hermissenda opalescens, Box Canyon, Neah Bay, Washington, 20 August 2015. Image by Doug Miller.