Doto splendida, Pola & Gosliner, 2015

Pola, Marta & Gosliner, Terrence M., 2015, A new large and colourful species of the genus Doto (Nudibranchia: Dotidae) from South Africa, Journal of Natural History 49, pp. 1-17 : 5-9

Doto splendida sp. nov.

( Figures 1–3)

Doto sp. I Pola and Gosliner, 2010: 935

Type material

Holotype: adult specimen, 5 mm preserved ( South Africa, western Cape Province, western False Bay, Miller’ s Point , 34°13.84 ′ S, 18°28.47 ʹ E; intertidal, found feeding on Eudendrium [ California Academy of Sciences ( CASIZ176124 )]. Collected by T. M. Gosliner, 3 January 2008.

Paratype: one adult specimen completely dissected and sequenced for molecular studies, 20 mm alive (10 mm preserved), water depth: 3 m (same locality, date and collector as holotype) [ CASIZ176123 ] .

Etymology

The specific name refers to the beautiful and conspicuous colour of the animal. From the Latin word splendidus, meaning brilliant, magnificent appearance.

Distribution

Thus far this species is only known from Western Cape Province, South Africa.

External morphology ( Figure 1)

The body is slender and elongate ( Figure 1A). Its length reaches 20 mm alive. The head bears a pair of smooth rhinophores with blunt apices, surrounded by rhinophoral sheaths that reach half of the total length of the rhinophores in living specimens ( Figure 1A). The sheaths are rather slender, the diameter being double that of the rhinophore itself. Above, the sheaths are undulate, trumpet-shaped with their anterior side ending with a rather long, tongue-like projection at the upper end ( Figure 1A). A wide oral veil is present in front of the rhinophores. It is entire, rounded and expanded laterally, without projections. On each side of the body, up to 7 cerata occur, the hindmost usually being smaller than the anterior and middle cerata. The cerata are large, elongate, with rounded tubercles that decrease in size basally towards the body. The base of the cerata is not pedunculate. Each ceras bears six or seven rings of six–seven simple or more complex semiglobular tubercles and one larger tubercle at the top ( Figure 1A, B). At the inner side of a ceras a pseudobranch is situated with 4–5 ramifications of varying lengths. The genital opening is located slightly below and in front of the first ceras on the right side, and protrudes as a cylindrical genital papilla. On this side, between the first and second cerata, the anus and nephroproct together form a prominent papilla. The pericardium starts just behind the first ceras. The posterior end of the foot is long and limaciform ( Figure 1A). The posterior end of the foot is narrow and extends slightly from under the mantle. The pericardium forms a swelling on the back, between the first and second cerata.

Colouration ( Figure 1). The body is transparent, with a faint orange hue covered with occasional small opaque white dots dispersed over the frontal veil, the upper half of the rhinophores, the borders of their sheaths, the posterior end of the foot and the tubercles of the cerata. The yellow digestive gland is clearly visible through the transparent faint orange body wall. The branches of the digestive gland in the cerata are intense pink. The tubercles of the cerata are faint orange, similar to the ground colour with small white dots more or less abundant ( Figure 1A, B). The foot is transparent.

Internal anatomy ( Figures 2, 3)

The jaws are very thin with a smooth masticatory process. The uniseriate radula is composed of 85 horseshoe-shaped teeth with three strong lateral denticles on either side of the median cusp ( Figure 2A, B). The salivary glands are located just in front of the buccal bulb. They have a globular appearance opening into the oesophagus via a thin duct. Furthermore, above and at the posterior end of the salivary glands, there are three rounded giant cells. The pedal gland lies at the anterior part of the foot and around the oral opening. It is composed of numerous semispherical follicles.

The reproductive system is androdiaulic ( Figure 3). The hermaphroditic gland is granulate, appearing as a compact mass clearly visible under the mantle. It is connected with the ampulla by a narrow hermaphroditic duct. The ampulla is large, thick and elongate. The rather long, postampullary duct splits into the vas deferens and the oviduct. The vas deferens begins as a large pyriform prostate gland and then tapers into a long and thin vas deferens with several loops and entering into the muscular penial bulb. Within the penial bulb is the elongate, conical and unarmed penis ( Figure 2B, C). The oviduct is rather wide and elongated, forming a U-shaped loop before it dilates into the seminal receptacle, a spacious sac similar in length and width to the prostate gland. It continues with the vagina, which is short and slender. The female glands are very well developed and open together with the vagina.

Molecular data ( Figure 4)

As indicated in Table 1, some gene fragments were not available for the analysis; in particular some nuclear fragments of the gene H3 and some 16S fragment for some isolated species of Doto are missing. After alignment 1472 bp were used. We obtained 18 new sequences; 6 for H3, 6 for COI and 6 for 16S. The saturation plots of uncorrected differences against corrected sequence divergence divided by codon indicated no saturation for any gene (not shown). Figure 4 shows the phylogenetic hypothesis based on the combined data set represented by BI.

Figure 4 clearly indicates that D. splendida sp. nov. represents a distinct lineage and that it clusters with two eastern Pacific (from the Pacific coast of Mexico and California, respectively) species rather than with any other Atlantic taxa. The available species of Doto constitute a clade with the maximum support (PP = 1; BS = 100). Doto pinnatifida , D. coronata , D. eireana , D. floridicola and D. koenneckeri form a well-supported clade (PP = 0.98; BS = 78) while D. splendida sp. nov. clusters with D. columbiana and Doto sp. H (PP = 0.99; BS = 72). The phylogenetic relationship of this clade with the one including D. antarctica , Doto sp. 2, Doto sp. 7, Doto sp. K and D. ussi (PP = 0.98; BS = 87) is not resolved. DNA sequences for Doto rosea are not available, but the morphological differences highlighted below clearly separate D. rosea of the new species. The sister taxon to the genus Doto is not yet fully resolved. Figure 4 shows that Hancockia californica is closer than Notobryon or Dendronotus , but this relationship is not supported either by the analysis of Bayesian inference nor by maximum-likelihood analysis.