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PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES 
Series 4, Volume 65, 28 Sept. 2018, No. 3 
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 Nino 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 Nino Southern 
Oscillation (ENSO). 
Hermosita hakunamatata (Ortea, Caballer and Espinosa, 2003). Punta Entrada, Isla Mag¬ 
dalena, Bahia 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 Bahia 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 Bahia Magdelena. 
Noumeaella rubrofasciata Gosliner, 1991. Outer Pinnacles, Carmel Bay, California, 1 speci¬ 
men, 43 m depth, 4 March 2017 (C. Bauder, personal communication to JG, 5 March 2017; Baud- 
er 2017) to Panama (Hermosillo 2004). 
Previous northe rnm ost 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 hiltoni (O’Donoghue, 1927). Pinnacle Rock, Bodega Bay, Sonoma Co., California, 
7 specimens, low rocky intertidal, 25 November 2015 (Sones 2015) to Cedros Island, Baja Cali¬ 
fornia, 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 individ¬ 
uals 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 persist¬ 
ence 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 sig¬ 
nificant 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 
