Dendronotus kamchaticus Ekimova, Korshunova, Shepetov, Neretina, Sanamyan & Martynov, 2015

Korshunova, Tatiana, Bakken, Torkild, GrØtan, Viktor V., Johnson, Kjetil B., Lundin, Kennet & Martynov, Alexander, 2021, A synoptic review of the family Dendronotidae (Mollusca: Nudibranchia): a multilevel organismal diversity approach, Contributions to Zoology 90 (1), pp. 93-153 : 123

Dendronotus kamchaticus Ekimova, Korshunova, Shepetov, Neretina, Sanamyan & Martynov, 2015

Fig. 7

Dendronotus kamchaticus Ekimova, Korshunova, Shepetov, Neretina, Sanamyan

& Martynov, 2015: 869–872, Figs 6E , 8D , 16A, B, 17, 18A; Korshunovaet al., 2016a: 32–36, Figs 4C, D , 5 .

Extended diagnosis. Body narrow. Five to six pairs of branched dorsolateral appendages. Four to six oral veil appendages. Five to six appendages (apparently similar in size or posterior longer) of rhinophoral stalks. Lateral papilla of rhinophoral sheaths present. Rhinophoreswith 5–11 lamellae. Lip papillae 4–15. Basal colour semitransparent to brownish with irregularly scattered small brownish dots. Dorsalprocessesof jaws inclined posteriorly at approximately 70° to the longitudinal axis of the jaw body and 0.37 of its length. Masticatory processes possibly beardenticlesandridge-likestructures.Radula with upto 44 rows of teeth. Central tooth with almost completely reduced denticles and furrows at adult stages, subadults may bear small denticles. Up to eleven lateral teeth with up to nine denticles. Ampulla moderately voluminous with several (at least two or three) folded loops. Bursa copulatrix large, rounded. Seminal receptaculum small, placed distally at a moderately short distance from the vaginal opening. Prostate discoid with circa 7–25 alveolar glands. The vas deferens is moderate in length, penis relatively long, slightly curved. Body length up to 30 mm.

Distribution. NW Pacific from Kamchatka to Japan Sea, Russia, and NE Pacific in Salish Sea, Canadaand USA.

Bathymetry. 7–17 mdepth.

Remarks. Though this species previously was confused with D. frondosus , D. albus and D. venustus , D. kamchaticus is well delineated from those species according to the morphological features (semitransparent grayish with white-tipped dorsolateral appendages and digestive gland often penetrating all branches of all dorsolateral appendages to body brownish colouration without dorsal subparallel stripes), radular patterns (usually almost smooth central teeth in adults) and molecular phylogenetic data (figs1,2).Intheoriginaldescriptionbranchesof the dorsolateralappendages were incorrectly described as bulbous and short (see Ekimova et al., 2015: Fig. 8D ), despite the presence of this species in the same paper ( Ekimova et al., 2015: Fig. 16A, B) represented by photos of live paratypes with more elongated, not exactly bulbous, though still shortened branches. Further, in a specimen of D. kamchaticus from the Sea of Japan the branches were described as elongated and also very different from the original description and Fig. 8D in Ekimova (2015). This significant discrepancy compared with the original description was explained: “because different ontogenetic stages were used in the description and this study, as well as cerata morphology may be altered in preserved specimens” ( Ekimova et al., 2016: 38). However, this discrepancy was not due to the different ontogenetic stages. In the original description of D. kamchaticus , the typespecimenswererepresentedbyanalmost adult holotype (12 mm preserved length) with a mature reproductive system whereas seven paratypes were subadults (2–10 mm of preserved length). Most importantly, the drawinginEkimova(2015: Fig.8D )depictedthe largest holotype, with an adult reproductive system and the artificially bulbous branches were only seen in the preserved specimen, without any considerable ontogenetic modifications. The largest specimen so far known of D. kamchatcius (adult, 30 mm) from the NE Pacific, also has considerably elongated branches ( Korshunova et al., 2016a). This fully confirms that the branches were described and figured incorrectly in the original description.

Figures

FIGURE 4 Dendronotus yrjargul sp.nov.(a–n) and D.kalikal (o–t), external and internal morphology.a–c: living holotype of D.yrjargul NTNU-VM-76306 (a) and its habitat (b, c), dorsal,ventral and lateral views with egg mass and associated hydroid Abietinaria fusca, respectively; d: Dendronotus yrjargul, habitat of living paratype NTNU-VM-76302;e: jaw of holotype; f:denticles on the masticatory edge of the holotype; g: jaws of paratype NTNU-VM-76302; h:discoid ridge-like structures on the masticatory edge of paratype NTNU-VM-76302;i: details of discoid structures on the masticatory edge of paratype NTNU-VM-76302; j: anterior part of radula of holotype; k:central teeth of radula of holotype;l:lateral teeth of radula of holotype; m:central teeth of radula of paratype NTNU-VM-76302; n: lateral teeth of radula of holotype; o: living holotype of D.kalikal; p: jaw of D.kalikal, specimen from Kurile Islands;

FIGURE 5 Dendronotus nordenskioeldi sp. nov.ZMMU Op-665, external and internal morphology.a–b:living holotype, dorsal and lateral views respectively;c:ventral view of preserved holotype;d: jaw of holotype; e: irregular denticles on the masticatory edge of the holotype;f:posterior part of radula; g:central teeth of radula; h: lateral teeth of radula of holotype.Scale bars: d: 1mm; e: 20 µm; f:100 µm; g, h: 30 µm. PHOTOGRAPHS BY O. ZIMINA (A, B) AND T. KORSHUNOVA (C). SEM MICROGRAPHS BY A. MARTYNOV

FIGURE 6 Reproductive systems. a, Dendronotus yrjargul sp. nov.; b, D.kalikal; c, D.elegans; d, D. nordenskioeldi sp. nov. Scale bars:a–d 1mm.Abbreviations:am, ampulla; bc, bursa copulatrix; fgm, female gland mass; fo, female opening; p, penis; pr, prostate; rs, receptaculum seminis; ud, uterine duct; vd, vas deferens; vg, vaginal duct.

FIGURE 7 Representaives of the genus Dendronotus (living specimens). PHOTOGRAPHS BY T. KORSHUNOVA, A. MARTYNOV, K. FLETCHER, D. MILLER, Y. FUJIWARA, K. HASEGAWA, K. SANAMYAN, N. SANAMYAN, AND O. ZIMINA

FIGURE 8 Dendronotus elegans. External and internal morphology.a: living specimen ZMMU Op-713 from Greenland, near East Atlantic North American coast; b: jaw, same specimen; c; posterior part of radula, general overview,same specimen; d: close up of smooth central teeth, same; e: close up of lateral teeth, same; f:living specimen ZMMU Op-714 (as “D.niveus”) from the White Sea (subarctic); g: jaw, same specimen; h:masticatory edge of the jaws,same; i: posterior part of radula, general overview,same specimen; j: close up of smooth central teeth, same; k: living specimen ZMMU Op-715 from the Laptev Sea (Arctic); l: jaw, same specimen; m: posterior part of radula, close up of smooth central teeth, same; n: lateral teeth, same.o: discoid prostate with numerous alveols (which considerably exceed the considerably underestimated number presented in the first description of D.niveus), same specimen; Scale bars: b, l, 1mm; c: 300 µm; d, h–j, m: 100 µm; g: 1000 µm; e, n: 30 µm. PHOTOGRAPHS BY O. ZIMINA (A, K) AND T. KORSHUNOVA (F). SEM MICROGRAPHS BY A. MARTYNOV