Dendronotus jamsteci

Martynov, Alexander, Fujiwara, Yoshihiro, Tsuchida, Shinji, Nakano, Rie, Sanamyan, Nadezhda, Sanamyan, Karen, Fletcher, Karin & , 2020, Three new species of the genus Dendronotus from Japan and Russia (Mollusca, Nudibranchia), Zootaxa 4747 (3), pp. 495-513: 500-503

publication ID

https://doi.org/10.11646/zootaxa.4747.3.4

publication LSID

lsid:zoobank.org:pub:357D0749-89D1-4DE4-8BDE-A32F40C4EF38

DOI

http://doi.org/10.5281/zenodo.3704153

persistent identifier

http://treatment.plazi.org/id/03DB1E58-0B21-FFC3-0889-4C6CFC45FEE6

treatment provided by

Plazi

scientific name

Dendronotus jamsteci
status

sp. nov.

Dendronotus jamsteci  sp. nov.

( Figures 1–2View FIGURE 1View FIGURE 2, 5AView FIGURE 5)

http://zoobank.org/ B8DAC5AC-56F4-4C92-90EC-D48C5173772A

Type material. Holotype, JAMSTEC No. 1160047475, 17.5 mm long preserved, dissected, Cruise KS-16-J03, on board ID HPD #1952, Japan, Northern Honshu , off Otsuchi, 39° 18.5378’ N 142° 17.82’ E, 08 March 2016, depth— 670 m, collector Shinji Tsuchida. One paratype, JAMSTEC No. 1160047461, Cruise KS-16-J03, on board ID HPD #1952-07, Dive No. HPD #1952, 21.5 mm long (preserved), Japan, Northern Honshu , off Otsuchi, 39° 18.4453’ N 142° 18.0498’ E, 08 March 2016, depth— 761 m, collector Shinji Tsuchida. Five paratypes, JAM- STEC No. 1160047464, Cruise KS-16-J03, on board ID HPD #1952-10, Dive No. HPD #1952, 2– 7 mm long (preserved), Japan, Northern Honshu , off Otsuchi, 39° 18.4453’ N 142° 18.0498’ E, 08 March 2016, depth— 761 m, collector Shinji Tsuchida. Ca.GoogleMaps  GoogleMaps  GoogleMaps  60 paratypes, JAMSTEC No. 1160047463, Cruise KS-16-J03, on board ID HPD #1952-09, Dive No. HPD #1952, 1.5–15 mm long (preserved), Japan, Northern Honshu , off Otsuchi , 39°18.4453’ N 142°18.0498’ E, 08 March 2016, depth— 761 m, collector Shinji Tsuchida. Three paratypes, JAMSTEC No. 1160047392, Cruise KS-16-J03, on board ID HPD #1950-16, Dive No. HPD #1950, 11– 11.5 mm long (preserved), Japan, Northern Honshu , off Otsuchi , 39° 18.7059’ N 142° 18.0498’ E, 05 March 2016, depth— 684 m, collector Shinji Tsuchida. Nine paratypes, JAMSTEC No. 1160047475, Cruise KS-16-J03, on board ID HPD #1952, 2 – 21 mm long, Japan, Northern Honshu , off Otsuchi , 39° 18.5378’ N 142° 17.82’ E, 08 March 2016, depth— 670 m, collector Shinji Tsuchida. Three paratypes, JAMSTEC No. 1160047380, Cruise KS-16-J03, on board ID HPD #1950- 4, 7– 18 mm long (preserved), Japan, Northern Honshu, off Otsuchi, 39° 18.6579’ N 142° 18.0498’ E, 05 March 2016, depth— 704 m, collector Shinji Tsuchida.GoogleMaps  GoogleMaps  GoogleMaps  GoogleMaps 

Type locality. Japan, off the Pacific coast of Northern Honshu  .

Etymology. In honour of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) which has made a considerable contribution to the understanding of deep-sea fauna in Japan and worldwide.

Diagnosis. Body elongate, 6–7 pairs dorsolateral appendages, colour whitish with brownish spots and streaks, central tooth with well-defined denticles and furrows, vas deferens moderate in length, penis conical, moderately narrow.

Description. Body elongate, up to 21.5 mm in length ( Fig. 2A, BView FIGURE 2), 6–9 branched appendages of oral veil, 4–5 appendages of rhinophoral stalks, 12–15 rhinophoral lamellae, branched rhinophoral lateral papilla present, 6–7 pairs dorsolateral appendages, 20–25 lip papillae. Dorsolateral appendages with thickened primary stalk, moderately branched secondary branches, and blunted tertiary branches ( Fig. 2A, CView FIGURE 2). Reproductive and anal openings placed laterally on right side. General colour whitish with scattered distinct opaque white dots on notum, tips of lateral appendages, oral appendages, lip papillae, and rhinophores ( Fig. 2CView FIGURE 2).

The jaws are ovoid with strong dorsal processes, denticles present. Masticatory processes bear ca. 60 denticles (holotype, including simple triangular and broadly lamellated ones ( Fig. 2D, EView FIGURE 2). Radula formula is 33 × 1–6.1.6–1 (paratype 7 mm), 34 × 3–8.1.8–3 (holotype), 38 × 3–8.1.8–3 (paratype 20 mm), 29 × 3–8.1.8–3 (paratype 21.5 mm). Central tooth strongly denticulated and bearing up to 17 distinct denticles ( Fig. 2FView FIGURE 2) with well-defined furrows. Lateral teeth are short, slightly curved, bearing up to 9 long denticles ( Fig. 2GView FIGURE 2).

Reproductive system triaulic ( Fig. 5AView FIGURE 5), ampulla moderately thin, triple folded ( Fig 5AView FIGURE 5, am), prostate consisting of 50–60 alveolar glands ( Fig. 5AView FIGURE 5, pr), vas deferens moderate in length ( Fig. 5AView FIGURE 5, vd) expanding to a narrow penial sheath ( Fig. 5AView FIGURE 5, psh), penis short and conical ( Fig. 5A, pView FIGURE 5), vagina long and twisted ( Fig. 5AView FIGURE 5, vg), bursa copulatrix is medium-sized, rounded ( Fig. 5AView FIGURE 5, bc) with small seminal receptaculum placed distally ( Fig. 5AView FIGURE 5, rs).

Biology. On hydroids within sand and muddy substrates.

Distribution. Presently known only off the Pacific coast of Northern Honshu ( Japan), at depths of 670– 761 m.

Remarks. Dendronotus jamsteci  sp. nov. is superficially similar to D. frondosus  and D. primorjensis  , but different in the details of 1) colouration: compared to D. frondosus  and D. primorjensis  , D. jamsteci  sp. nov. has a weakly coloured whitish ground colour with dispersed brownish spots), 2) radula: D. jamsteci  sp. nov. has different number of rows (up to 8 in D. jamsteci  sp. nov., up to 9 in D. primorjensis  , up to 10 in D. frondosus  ) and denticles on the central (up to 17 denticles in D. jamsteci  sp. nov., up to 18 in D. primorjensis  , up to 14 in D. frondosus  ) and lateral tooth (up to 9 denticles in D. jamsteci  sp. nov., up to 8 in D. primorjensis  , up to 7 in D. frondosus  ), and 3) reproductive system: D. jamsteci  sp. nov. considerably differs in the number of alveolar glands (50–60 in D. jamsteci  sp. nov., 12–19 in D. primorjensis  , 16–30 in D. frondosus  ) as well as details in the patterns of the bursa and copulative organ arrangements. Importantly, according to the molecular phylogenetic data ( Fig. 1View FIGURE 1), D. jamsteci  sp. nov. doesn’t belong to the clade comprised of D. frondosus  , D. primorjensis  and D. venustus  (this species readily differs externally from D. jamsteci  sp. nov. by its bright yellow markings or large amounts of opaque white pigment) ( MacFarland 1966; Stout et al. 2010) but is sister to the clade that includes D. subramosus  and D. albus  . However, both the latter species are considerably different morphologically from D. jamsteci  sp. nov.. Particularly, although D. subramosus  externally shares a similar brownish colouration with D. jamsteci  sp. nov. it lacks lateral rhinophoral papilla common in most species of the genus Dendronotus  including D. jamsteci  sp. nov. By this feature, it readily differ from D. jamsteci  sp. nov., whereas D. albus  considerably differs from D. jamsteci  sp. nov. by its uniform whitish or lilac colour and patterns of the radula and reproductive system. Such a discrepancy of molecular and morphological evolution is very interesting. From the NW Pacific species D. kalikal  , D. jamsteci  sp. nov. differs by the absence of subparallel brownish dorsal stripes, details of the radula and very significantly by the molecular data ( Fig. 1View FIGURE 1). Two other NW Pacific species, D. kamchaticus  and D. zakuro  sp. nov., are substantially different from D. jamsteci  sp. nov. by their colouration and the smooth central teeth of their radula at the adult stage and in addition, they belong to a different molecular clade ( Fig. 1View FIGURE 1). None of these species inhabit bathyal depths as D. jamsteci  sp. nov. does, and their bathymetric distribution is restricted to shallow waters, not deeper than 60 m. Recently, a deep-sea species off the NE Pacific coast, D. claguei, was described ( Valdés et al. 2018). For that species, only H3 gene data was provided in the cited publication, so the absence of COI and 16S data prevented its use here for molecular analysis because the H3 gene is almost identical for closely related species of the genus Dendronotus  . D. claguei fundamentally differs from D. jamsteci  sp. nov. by its uniform translucent white colour, radular details, and in addition D. claguei inhabits upper abyssal depths (2369 m) and not upper bathyal depths (670–761 m) as D. jamsteci  sp. nov. does. Maximum intraspecific and minimum interspecific genetic distances for the COI marker in the species of the genus Dendronotus  including D. jamsteci  sp. nov. are presented in Table 2.