Doto kwakwak Gosliner & Adayapalam, 2025

Doto kwakwak Gosliner & Adayapalam View in CoL sp. nov.

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( Figs. 2E–F View FIGURE 2 , 3C View FIGURE 3 , 5B View FIGURE 5 , 6 View FIGURE 6 )

Doto sp. 4 — Behrens et al., 2022: 114, lower photos.

Type material. Holotype. CASIZ 234657 , 4.5 mm preserved, off Cuvier Park 32.843073°N – 117.281888°E, La Jolla, California, 27 February 2022, Chloe and Trevor Van Loon collectors. GoogleMaps

External morphology ( Fig. 2E–F View FIGURE 2 ). The living animal has a translucent white body color with a cream colored ovotestis visible through the body. There are small opaque white spots visible along the margins of the foot, along the margin of the rhinophore sheath, and on the entire length of the rhinophore. The dorsal notum and sides of the body have numerous scattered ovoid saffron yellowish orange spots, some of which have irregular borders and are slightly raised. The digestive gland within each ceras is light brownish with opaque white glands present within the tubercles on the cerata. There are 7 pairs of cerata with 4 whorls of elongate tubercles with bulbous tips. The size of the tubercles varies, but in general the more basal ones are smaller with the largest being the single terminal tubercle. The cerata often lack pseudobranchs but in one large ceras the pseudobranch consisted of a single linear axis without lateral branches. The rhinophoral sheaths are well-elevated from the notum with an extension on the anterior side. The head is broader than the rest of the body with a pair of curved lobes situated laterally. The anal papilla is situated dorsally, posterior to the second right ceras and genital openings on right side of body, immediately ventral to the first ceras. On the head of one specimen, photographed from off the east end of Santa Cruz Island, there is a brown patch of what appears to be a subcutaneous pigmentation ( Klug, 2019). An additional specimen, from off the Palos Verdes Peninsula and included in Behrens et al. (2022) has subcutaneous black streaks extending from the head to near the posterior end of the body.

Buccal armature ( Fig. 6 View FIGURE 6 ). The buccal mass is small and muscular. The jaws are thin and membranous. The radula is elongate and narrow, consisting of a ribbon of at least 69 teeth. The teeth are simply arched posteriorly with a series of anterior denticles. Each tooth has an elongate central cusp that extends more anteriorly than the lateral denticles. There are one to two pairs of elongate denticles on either side of the central cusp. On the outer side of the tooth there are an additional 1–2 smaller denticles on either side of the tooth.

Reproductive system ( Fig. 5B View FIGURE 5 ). The reproductive system is androdiaulic. The pre-ampullary duct is short and expands into the wide, ovoid ampulla. The ampulla again narrows distally and divides into the oviduct and vas deferens. The oviduct widens into a serial receptaculum seminis that narrows into an elongate curved vagina that terminates at the female gonopore adjacent to the penis. The vas deferens widens into a curved, thickened prostatic portion and narrows into a thin, curved ejaculatory portion. The distal end of vas deferens enters the thick, curved penial sac, which terminates adjacent to the opening of the vagina. The female glands are not well differentiated from each other, but the mucous gland comprises the bulk of the organs and terminates adjacent to the opening of the vagina and penis and has a separate aperture.

Etymology. The species epithet comes from the Kumeyaay indigenous name kwakwak, meaning yellow, signifying the yellow-orange spots on the notum that distinguish this species. The Kumeyaay are the original inhabitants of the region around the type locality in San Diego County.

Distribution. Known intertidally from La Jolla, and subtidally from off the Palos Verdes Peninsula, Isla Vista, and Anacapa and Santa Cruz Islands, California, USA ( Behrens et al., 2022, present study).

Remarks. This species is known only from a few photographs and the only documented specimen collected is the holotype, from La Jolla, CA ( Fig. 2E View FIGURE 2 ) ( Van Loon, 2022). Six other specimens have been photographed: three from Anacapa Island in the Channel Islands by Johnson (2018) ( Fig. 2F View FIGURE 2 ) and Klug (2017, 2020); one from Santa Cruz Island in the Channel Islands ( Klug, 2019); one by Margaret Webb from off Haggerty’s, Palos Verdes, CA ( Behrens et al., 2022); and one from the shallow subtidal off Coal Oil Point, Isla Vista, CA by Mazza (2019).

In our phylogeny, Doto kwakwak and Doto kya are sister to most of the other members of the Atlantic/eastern Pacific clade ( Fig. 1 View FIGURE 1 ). Of the species found along the Pacific coast of the United States and Canada, it can be readily distinguished externally by the presence of yellowish-orange spots on the body. Similarly, D. kwakwak , like D. amyra and D. urak , generally lacks the scattered brown pigment on the body that is found in D. kya and D. columbiana , but some specimens may have subcutaneous dark pigment ( Klug, 2019). In D. amyra , the lateral extensions of the foot are elongate, whereas, they are much shorter in D. columbiana , D. kya , D. lancei Marcus & Marcus, 1967 , D. urak , and D. kwakwak . In D. urak and D. kwakwak , the rhinophore sheaths are flared apically while they are largely cylindrical in D. amyra , D. columbaiana , D. kya , and D. lancei . The ceratal tubercles of D. kwakwak , D. urak , D. lancei , and D. kya are spherical to elongate apically, while those of D. columbiana and D. amyra are much lower to flattened or irregular in shape ( Fig. 3B View FIGURE 3 ). Also, the opaque white glandular apices of the ceratal tubercles of D. kwakwak , D. urak , and D. kya differ from those of D. columbiana , D. lancei , and D. amyra , which lack opaque white on the tubercle apices. Doto kwakwak has many tubercles of different sizes shapes (some bulbous and some longer), in contrast to D. amyra , D. urak , D. lancei , D. columbiana , and D. kya , which have uniformly tuberculate cerata. The cerata or D. kwakwak are elongate like those of D. amyra , D. kya , D. lancei , and D. columbiana , but tend to get longer towards the posterior end of the body. The cerata of D. urak are shorter and more rounded. The digestive gland within the ceratal core of D. kwakwak appears to be a much more vibrant rust/red color, than in D. kya , D. lancei , and D. columbiana , which have beige to light orange cores. In D. kwakwak , a pseudobranch is either absent from the inner side of the cerata or if present is only an unbranched vertical line. In all other eastern Pacific species of Doto a well-developed, branched pseudobranch is present ( Fig. 3B View FIGURE 3 ).

As stated in the remarks regarding D. urak , the species of Doto from the Pacific coast of North America all have similar radular tooth morphology, and there is nothing distinctive about the radular teeth of D. kwakwak . The reproductive system of D. kwakwak is similar to that of D. columbiana ( Marcus, 1961a: fig. 129) with a relatively short, curved ejaculatory segment and a relatively short penial sac. However, the vaginal duct of D. columbiana has a distinct sphincter as in D. amyra , in contrast to that of D. kwakwa k ( Fig. 5B View FIGURE 5 ), D. urak ( Fig. 5A View FIGURE 5 ), and D. kya ( Marcus, 1961a: fig. 140).

Doto kwakwak is molecularly distinct and is a single distinct species according to each species delimitation method undertaken. D. kwakwak interspecific p -distances to the closest species are: 12.51–12.99% to Doto amyra , 14.27% to D. columbiana , 14.09–14.46% to D. kya , 13.54–14.64% to D. lancei , 12.47–12.84% from D. sp. B, 14.09% to D. sp. C, 14.83% to D. sp. I, and 13.90–14.93% to D. urak .

Little is known about the natural history of this species and its larval biology and development mode remains unknown.