Doto urak, Gosliner & Adayapalam, 2025

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

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( Figs. 2A–D View FIGURE 2 , 3A View FIGURE 3 , 4 View FIGURE 4 , 5A View FIGURE 5 )

Doto amyra View in CoL — Behrens, 1980: 77, lower left photo, misidentification; Behrens, 1991: 78, upper photo, misidentification; Behrens & Hermosillo, 2005: 96, middle photo, misidentification.

Doto sp. form A— Goddard, 1996; Shipman & Gosliner, 2015; Behrens et al., 2022: 112, lower left photo.

Type material. Holotype. CASIZ 182040 , Cabrillo launch ramp 33.713231°N – 118.283415°E, San Pedro Harbor, 12 December 2009, Á. Valdés collector. GoogleMaps

Paratypes: CASIZ 056222 , 15 specimens, mouth of Drake’s Estero Marin County, CA, 24 April 1984, Jeff Goddard, collector. GoogleMaps CASIZ 184511 , 7 specimens, one dissected, Ellwood boulder field, between Gaviota and Goleta , Santa Barbara County, California, 15 March 2010, Jeff Goddard collector. GoogleMaps CASIZ 217592 , one specimen, Santa Cruz boat harbor 35.964552°N – 122.001849°E, Santa Cruz, CA, 18 August 2017, Brenna Green, collector. GoogleMaps CASIZ 217599 , one specimen, Santa Cruz boat harbor 35.964552°N – 122.001849°E, Santa Cruz, CA, 18 August 2017, Brenna Green, collector GoogleMaps .

External morphology ( Fig. 2A–D View FIGURE 2 ). The living animals are 4–7 mm in length and the preserved holotype is 4.5 mm. The body color is translucent white with cream colored ovotestis visible through the body wall. There are a few to many small opaque white spots visible on the tips of the rhinophores not extending to the sheath or the head. The rhinophores extend just slightly above the sheath, which is well elevated from the notum. The apical margin of the rhinophore sheath is flared and of uniform width around the entire margin or wider anteriorly, and a few opaque white spots are occasionally present along the sheath margin. The digestive gland within each ceras ranges from a peach salmon to vibrant pinkish red. There are 4–7 pairs of cerata with around 15 tubercles on each ceras. The well-spaced tubercles are arranged in about 3–5 loosely organized whorls and are ovoid in shape. Each tubercle has an opaque white glandular apex. In some individuals ( Fig. 2C View FIGURE 2 ) cerata have been lost and are regenerating. The pseudobranch ( Fig. 3A View FIGURE 3 ) has up to five palmately lobed branches that are situated near the base of each ceras on the inner side. The anus is located on the right side between the first and second cerata. The genital opening is situated under the first ceras on the right side. The head is rounded with short, rounded extensions visible laterally.

Buccal armature ( Fig. 4 View FIGURE 4 ). 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 75 teeth. The asymmetrical 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. The first two denticles on either side of the central cusp are offset, giving the tooth an asymmetrical appearance. There are two to three 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. 5A 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 convoluted vagina that terminates at the female gonopore adjacent to the penis. The vas deferens widens abruptly into a curved, thickened prostatic portion and narrows into a thin, undulating ejaculatory portion. The distal end of vas deferens enters the large, straight 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 name urak comes from the southern Ohlone word for salmon, indicating the salmon pink to orange color of the cerata which is a distinctive feature of this species. The Ohlone people were the original inhabitants of much of the range of this species.

Distribution. Known from San Diego County to Humboldt County, California, USA.

Remarks. Doto urak is sister to D. amyra , and both are sister to D. columbiana . Doto urak is externally most similar to D. amyra and has been confused with this species previously (D. Behrens, 1980, 1991; D. Behrens & Hermosillo, 2005). Both species lack dark pigment on the body. Doto amyr a is distinctly longer than D. urak and can reach 12 mm in length. The rhinophores on most D. amyra specimens are proportionately shorter than those of D. urak . The rhinophore sheaths of D. urak are wide and more flared than those of D. amyra . The ceratal cores and digestive glands of D. amyra are a much lighter white/beige color, while those of D urak are generally a salmon pink to orange or dark rust/red color. Additionally, D. urak has ceratal tubercles with opaque white glands that are not evident in D. amyra . In D. urak , the ceratal tubercles are more widely spaced than in D. amyra . Also, the tubercles in D. urak are more rounded and regular in shape than the flatter ovoid tubercles of D. amyra . The cerata of D. amyra are usually longer, with some exceptions noted ( Agarwal, 2019) and also have more rows of tubercles. In D. amyra , the pseudobranch extends most of the length of the ceras with a few short lateral branches ( Marcus, 1961a, figs. 131, 132, 136) whereas D. urak has a palmately branched pseudobranch that is found basally on each ceras ( Fig. 3A View FIGURE 3 ). Previous literature on both species have indicated that D. amyra is more transparent than its counterpart, but some images suggest otherwise ( McDonald, 2017). The most significant difference is in the developmental biology of the two species: Doto urak lays eggs averaging 76 µm in diameter and has planktotrophic larvae, while D. amyra lays eggs averaging 152 µm in diameter and has lecithotrophic larvae (J. H. R. Goddard, 1996; Shipman & Gosliner, 2015).

Internally, the radular teeth of most of the northeastern Pacific Doto species are very similar in shape and appear to all have a certain degree of asymmetry ( Marcus, 1961a). The reproductive systems are also similar in form with a serial receptaculum seminis ( Marcus, 1961a), but do appear to differ in several details of their anatomy. In D. urak , the penial sac is more elongate than that of D. amyra ( Marcus, 1961a: figs. 134, 138 as D. wara , fig. 146 as D. ganda ), while the prostate is not as convoluted as in D. amyra . Also, there is a distinct muscular sphincter at the distal end of the vagina in D. columbiana ( Marcus, 1961a: fig. 129) and D. amyra ( Marcus, 1961a) that is apparently absent in D. urak and D. kya ( Marcus, 1961a) .

Doto urak is molecularly distinct (BI = 1, ML = 100) and is a single distinct species according to each species delimitation method undertaken. D. urak has an intraspecific variation p -distance of 0.00–1.90%. The interspecific p -distances between D. urak and the closest sister species are: 4.95–6.69% to Doto amyra , 7.90–9.09% to D. columbiana , 10.49–12.68% to D. kya , and 6.29–7.54% to D. sp. B.