Aplysia vaccaria Winkler, 1955
It's big. Very big. Possibly it is the largest known slug on earth. Keen (1971) reported specimens to 255 mm in total length; Winkler & Dawson (1963) reported specimens up to 30 inches (75 cm) in total length. This is slime personified! In an earlier Nudibranch of the Week (BOW #33), we illustrated Eveline Marcus holding in one hand Aplysia californica Cooper, 1863, and in the other Aplysia vaccaria Winkler, 1955. She was all smiles, as one could only expect a slug-aficionada to be.
As currently known, this species has a disjunct range; it has been reported from the Pacific coast of California and northeastern Baja California, from Monterey Bay (Behrens, 1991) to Cabo Colnett (Farmer, 1967); it has also been reported from inside the Gulf of California at Bahía de los Angeles (Lance, 1967) and Puertecitos (Farmer, 1968).
This species of anaspidean slug is characterized by its large size, black body coloration, firm body, and tight apposition of the parapodia; it does not produce purple ink as does Aplysia californica (Berhens, 1991). For a slug of this size, its internal shell is correspondingly huge.
Beeman (1968) discussed Aplysia vaccaria, but did not mention A. cedrosensis Bartsch & Rehder, 1939, even though it had been cited by Marcus (1961: 10) in Part One of the Veliger volume 3 supplement. There has been some discussion over the valid species of Aplysiinae in the northeastern Pacific. Farmer (1993) cited three species of Aplysia from the southern California: Aplysia californica, A. vaccaria, and A. cedrosensis. Based on the information he presented in his talk to the Western Society of Malacologists, there is a strong possibility that A. cedrosensis andA. vaccaria are synonyms, in which case A. cedrosensis would have taxonomic priority. The status of Aplysia reticulopoda Beeman, 1960, is a bit of an enigma; I suspect it has been synonymized with Aplysia vaccaria, but neither Dave Behrens nor I could find the reference. There is obviously a bit of work that can be done on these Aplysia species from the Pacific coasts of California and Baja California.
While diving at Piedras Plancas (27 51.8' N; 115 02' W), in the Punta Eugenia region, Baja Calfornia Sur, my colleagues and I found a copulating group of A. vaccaria with their egg mass. This seems to be the most southerly report of this species from the Pacific coast of the Baja California peninsula.
Part of this research was conducted under the auspices of a grant from the
Mexican federal biodiversity agency, CONABIO (Comisión Nacional para el
Conocimiento y Uso de la Biodiversidad). I am also grateful to Orso Angulo
Campillo and José Luis Arreola for field assistance.
Aplysia vaccaria photo courtesy of Wes Farmer
Send Wes E-Mail at firstname.lastname@example.org
Taxonomic Information and shell photo courtesy of Dr. Hans Bertsch