Adalaria olgae Martynov, Korshunova, Sanamyan & Sanamyan, 2009, sp. nov.

Adalaria olgae sp. nov.

(Figures 3 D, H; 6G–H; 7C; 10; 11E, F, H; 12C–D. Table 2)

Type Material. Holotype, ZMMU Lc-37451, NW Pacific near Kamchatka peninsula, Starichkov Id., 20–26 m depth, collected by T.A. Korshunova and A.V. Martynov, 14.08.2008. Paratypes, ZMMU Lc-37452, two dissected specimens, same locality and collectors as holotype, 20–25 m depth, 14.08.2008. Paratype, ZMMU Lc-37453, one dissected specimen, same locality and collectors as holotype, 19.08.2008. Paratypes, ZMMU Lc-37454, three specimens, same locality and collectors as holotype, 14.08.2008. Paratypes, ZMMU Lc- 37455, ten specimens, same locality and collectors as holotype, 14.08.2008.

Type locality. NW Pacific, SE Kamchatka, Starichkov Id., 18–26 m depth.

Etymology. Adalaria olgae sp. nov. is named in honour of the daughter of two authors (AM and TK). Description. External morphology. The dimensions of the holotype are 13.5 mm x 7 mm (Fig. 10). The length of 10 living specimens ranged from 5.5 to 13.5 mm, the width ranged from 3.5 to 7 mm. The consistency of the living animals is rather soft. The notum is moderately broad, rounded in front and posteriorly. The rhinophores are long and retract into sheaths with smooth edges, except for 3 tubercles of variable size at the edges of the sheaths (Fig. 10 D). The rhinophoral sheath edges are capable of some contraction in living specimens. There are 6–9 rhinophoral lamellae. The clavus of each rhinophore lacks a ridge posteriorly. The notum is densely covered with club-shaped or almost globular tubercles on a short stalk (Fig. 10 A). The top of the tubercles often has a peculiar wrinkled appearance, somewhat tulip-shaped (Fig. 10 C). The tubercles of the mid-notal area are somewhat wider and more globular than those at the notal edge. Larger tubercles are regularly intermingled with smaller ones. Rays of spicules radiating from the bases of tubercles form a network on the surface of the apparently soft notum (Fig. 6 G). The spicules are not conspicuous externally. Each tubercle contains dense bundles of spicules, which do not protrude through the tubercle surface. The strongly calcified spicules are of various sizes, some with a narrow channel inside, some solid (Fig. 6 H). A gill cavity is absent. Ten to thirteen unipinnate gills form a semicircle around the anus (Figs. 10 A, C). Within the gill circlet, one long and four shorter elongate tubercles are situated just before the anus. The oral veil, as in Adalaria slavi sp. nov., consists of a single, broad trapezoid anterior triangular projection which is medially not fused with the hyponotum, and two ventro-lateral flattened lobes (Fig. 10 B). The tentacular lobes are less defined than in Adalaria slavi, so the general appearance of the oral veil is more similar to other Adalaria and Onchidoris species (Figs. 8 A–C). The foot is broad, anteriorly rounded and thickened, and posteriorly slightly projecting beyond the notum in crawling animals forming a rounded tail (Fig. 10 A).

Colour. The living specimens have a remarkable, bright lemon yellow ground colour, which is constant in all studied specimens (Fig. 10). Under magnification the yellow pigment appears as numerous small dots. The rhinophores (including lamellae) are similar in colour to the ground colour. The upper part of tubercles is lighter. The gills are semitransparent-white, without traces of the yellow pigment (Fig. 10). Bright white gill glands are in the notum at the gill bases.

Anatomy. Digestive system. The anterior part of the buccal bulb is modified into the prominent buccal pump having a short, broad, but conspicuous stalk (Fig. 7 C). The buccal pump is fully banded by a relatively broad peripheral muscle (Fig. 7 C). The lateral sides of the buccal pump have thin muscular fibres. The rounded labial disk is covered by yellowish cuticle bearing fine distinct regular polygonal elements (Figs. 3 D, H). The radular formula in four specimens (11–13 mm length) is 30– 31 x 3–4.1.1.1.4–3. A few anterior radular rows have only two or three outer lateral teeth, whereas most of the further radula rows possess four laterals. Radular teeth are slightly yellowish. The central tooth is small, elongated, rectangular, and folded (Figs. 11 E, H). The first lateral tooth is provided with a long, wide base and a strong, slightly curved cusp. The cusp bears 4–8 denticles that are placed in a characteristic pattern. The outermost 1–3 denticles are conspicuously larger than the rest (Figs. 11 F, H). There is a prominent triangular knob medial to the denticular ridge and a poorly defined medial wing. Outer lateral teeth are slightly elongated plates, with a downward directed cusp on its lower outside corner, and all are similar in size and shape (Figs. 11 E–F). The stomach is relatively small and narrow. A stomach caecum is absent.

Circulatory system. In the pericardial sac the thin-walled, triangular posterior auricle and a smaller sized, oval ventricle are present. A well-defined blood gland lies above the central nervous system.

Central nervous system. The cerebral and pleural ganglia are well separated, the latter being somewhat smaller in size. The optic nerve is very short. The eyes are relatively large, with black pigment in all studied specimens. The pedal ganglia are smaller than the cerebrals, lay below them, and are connected to them by very short connectives. The rhinophoral ganglia are rather irregular, round or elongate. The buccal ganglia are roundish-oval. Gastro-esophageal ganglia are present. Five pairs of cerebral nerves, two pleural and three pedal ones are detected.

Reproductive system. (Figs. 12 C, D). The ampulla is long and wide, but not filled by sperm in all studied specimens and thus generally appeared inconspicuous (Figs. 12 C, D, a). The post-ampullar duct bifurcates into a thick prostatic loop and a proximal oviduct (Fig. 12 D). The prostatic part of vas deferens is a relatively long thickened loop (Figs. 12 C, D, pr), which does not encircle the bursa copulatrix. The prostate is wide, swollen, filled with sperm and not granulated. The prostate transitions into a long swollen single-looped penial sheath, which contains several loops of the ejaculatory part of the vas deferens (Fig. 12 C, psh). The inverted penial sheath and ejaculatory duct (penis) are long and rather thick, without spines, but have two additional short terminal knobs, not united into a singular structure (Figs. 10 E; 12D, p). The vagina is very short and somewhat widened (Fig. 12 D, v); it forms a short stalk to the relatively large globular bursa copulatrix (Fig. 12 D, bc) containing a pinkish-brown substance. The proximal oviduct is very short and indistinct, entering near the base stalk of the bursa copulatrix. The seminal receptacle is hardly distinguishable and just represented by an elevation of the bursa stalk (12D, rs). The combined distal oviduct and uterine duct emerges near the junction of the ampulla and seminal receptacle. This duct is long and wide, narrowing and diminishing within the nidamental glands (Figs. 12 C, D, dov).

Biology. Specimens were found predominantly on large boulders covered with several species of encrusting bryozoa, at 18–26 m depth, where the species is considerably less common than Adalaria slavi.

Distribution. Presently known only from the type locality.

Remarks. Adalaria olgae sp. nov. is well distinguished from other species of the genus by a number of characters. From A. proxima (Figs. 8 B; 11G) and A. loveni the present species markedly differs in having considerably fewer outer lateral teeth (3–4 instead of 9–13), by the shape of the first lateral tooth (curved beak shaped with small denticles instead of almost straight smooth cusp) by its relatively short and markedly swollen prostate, a penis with two short terminal knobs, by the different shape of the notal tubercles, the bright yellow-lemon ground colour with off-white gills, and also by its smaller body length. Adalaria tschuktschica (Figs. 11 I, M) and Lamellidoris spiculoides differ from Adalaria olgae in having spiniform, elongate notal tubercles, a semicircular oral veil without evident tentacle lobes and a larger number of distinctly shaped outer lateral teeth. Adalaria evincta significantly differs from Adalaria olgae by its globular tubercles on a very narrow stalk bearing distinctly protruding long spicules, and a couple of internal features that are summarized in Table 2. Adalaria jannae is found in Kamchatka waters, but more shallowly and never together with the new species (Fig. 8 A); it is well distinguished externally from Adalaria olgae in having smaller and more slender notal tubercles, a very hard notum with a translucent strong spicule network (Figs. 6 K; 8A), and the presence of a well defined postbranchial gland. Internally A. jannae also clearly differs from Adalaria olgae by its radula that is entirely devoid of central teeth, among other features (Table 2). Finally, the present species differs considerably from the sympatric and syntopic Adalaria slavi sp. nov. (Figs. 9; 11A–D) regarding colour, unipinnate versus bi- and tripinnate gills, less defined tentacle lobes on the oral veil, a stalked buccal pump, fewer outer lateral teeth and their shape, a swollen prostate, and the tiny knob-shaped seminal receptaculum that is integrated at the base of the bursal duct. The coloration of Adalaria olgae (intense lemon yellow with semitransparent-white gills) is especially remarkable and diagnostic. Whereas for some predominantly white onchidoridid species yellowish colour variations have been reported (e.g. for Adalaria proxima (Fig. 8 B) and Onchidoris muricata; Thompson & Brown 1984; Millen 1985) all collected specimens of Adalaria olgae showed a homogenous invariable intense lemon yellow colour, which markedly differs this new species from any yellowish onchidoridid colour varieties (including yellow and orange variants of A. jannae recorded from NE Pacific only). Its colour pattern also readily distinguishes Adalaria olgae from all other onchidoridids of similar size of the Kamchatka waters.

In the present study radulae of Adalaria olgae were compared with those of juvenile Adalaria proxima (Fig. 11 E–F and 11L respectively). Adalaria proxima at the length of ca. 10 mm transforms the denticulate first lateral teeth (Fig. 11 L) into a smooth one (Fig. 11 G) (Thompson 1958; Thompson & Brown 1984; present study). Adalaria olgae has denticulate first lateral teeth, and, at this size, already has a mature reproductive system. Thus, the first lateral teeth of the juvenile type persist in adult Adalaria olgae. Denticulation pattern, however, differs between A. proxima juveniles and Adalaria olgae: the former posess 2–3 large similar-sized denticles (Fig. 11 L), whereas the new species has usually more than 5 denticles, which are differentiated into larger and smaller ones (Fig. 11 F, H). All studied A. proxima specimens of 10–15 mm length (Barents Sea, Martynov et al. 2006) had immature, poorly developed reproductive systems but already entirely smooth first lateral teeth, whereas all investigated Adalaria olgae (8–13 mm) possess mature, well differentiated reproductive system and denticulated first laterals. Details of the reproductive system (for instance the very short vagina and distinct swollen prostate) and dorsal tubercles shape also significantly differ between Adalaria olgae and A. proxima (Table 2). Comparisions of the external shape of the adults and juveniles of A. proxima (Fig. 8 B and 8C respectively) and adult specimens of Adalaria olgae (Fig. 10) highlight these differences. Distinguishing features of Adalaria olgae sp. nov. are summarized in Table 2.