Baseodiscus princeps, (COE, 1901A)

Kajihara, Hiroshi, Abukawa, Shushi & Chernyshev, Alexei V., 2022, Exploring the basal topology of the heteronemertean tree of life: establishment of a new family, along with turbotaxonomy of Valenciniidae (Nemertea: Pilidiophora: Heteronemertea), Zoological Journal of the Linnean Society 196, pp. 503-548 : 538-539

BASEODISCUS CF. PRINCEPS ( COE, 1901 A)

( FIG. 3O–Q )

Baseodiscus curtus: Yamaoka, 1940: 234–236 , textfig. 13, pl. XVI, figs 8–11 (Akkeshi, Japan).

Baseodiscus princeps: Iwata, 1954: 15 ; Kajihara, 2017: 423, fig. 16.2e (Akkeshi, Japan).

Baseodiscus cf. princeps: Chernyshev, 2008: 271 , fig. 1F–I (Amursky Bay, Russia).

? Taeniosoma princeps Coe, 1901a: 173–177 , pl. XVI, figs 1–3, pl. XVIII, fig. 6 (Alaska).

Material examined: Three specimens. ICHUM 6339, extracted DNA and remaining body preserved in 99% EtOH; 12 June 2012, intertidal, under boulder, Daikoku-jima (42°57′39″N, 144°52′31″E), Hokkaido, Japan, collected by H. Kajihara. One specimen (DNA voucher: ICHUM 6340 ) , 8 July 2011, off Iturup Island (44°53.05′N, 147°15.18′), 114 m depth, collected by A. V . Chernyshev during cruise 41 of the S/ V Akademik Oparin. One specimen (DNA voucher ICHUM 6341 ) , 25 July 2005, Aniwa Bay (46°06.9′N, 142°15.7′E), 25 m depth, collected by A. V . Chernyshev during cruise 31 of the S/ V Akademik Oparin.

Sequences: From ICHUM 6339 : LC178604 , 18S (1785 bp) ; LC178636 , 28S (2119 bp) ; LC178685 , 16S (503 bp) ; LC190957 , COI (658 bp). From ICHUM 6340 : LC178605 , 18S (1797 bp) ; LC178637 , 28S (2090 bp) ; LC178686 , 16S (503bp) ; LC190958 , COI (658bp). From ICHUM 6341 : LC178606 , 18S (1796 bp) ; LC178638 , 28S (1202 bp) ; LC178687 , 16S (503 bp) ; LC190959 , COI (658 bp) .

Description: Background body colour bright yellow, dorsally mottled with irregular, light-brown patches often intensively fused together, especially in anterior part of body; dorsal mottling may extend ventrolaterally or even ventrally; body up to 30 cm long ( Fig. 3O–Q ).

D i s t r i b u t i o n: N o r t h - w e s t Pa c i f i c: i n t e r t i d a l, Akkeshi, Hokkaido, Japan ( Yamaoka, 1940; present study); subtidal, Far East Russia, Aniwa Bay (25 m) and off Iturup (114 m) (present study). Baseodiscus princeps s.s. was originally described from Alaska (Cape Fox, Yakutat, Orca), USA ( Coe, 1901a).

Remarks: This species was first reported as Baseodiscus curtus by Yamaoka (1940) from Daikokujima, Akkeshi Bay, Hokkaido, Japan. Iwata (1954) applied the name Baseodiscus princeps to it. As Chernyshev (2008) pointed out, specimens from Far Eastern Russia differ from B. princeps s.s. in that the dark-coloured markings are present not only dorsally, but also ventrally. Barcode sequences from topotypes should eliminate this uncertainty as to the application of the name princeps .

POTENTIAL FOOD ITEMS

Unidentified terebellid polychaete sequences were detected by BLASTn searches against the NCBI database of COI sequences derived from ICHUM 6315 and ICHUM 6316 ( B. hemprichii ), ICHUM 6320 ( B. quinquelineatus ) and ICHUM 6322 ( B. aff. marmoratus ), and a 28S sequence from ICHUM 6324 ( B. aff. maculosus ), each with ~85% identity values. Some of the cloned COI sequences (658 bp) from ICHUM 6310 ( B. narusei ) were 99% identical (differing by two bases in 658 bp) with AB430534, from an octopus identified by Kaneko et al. (2011) as Octopus cyanea Gray, 1849.

Chernyshev & Polyakova (2018: 124) stated: ‘Some sequences isolated in the process of cloning of COI sequences from the specimen of Sonnenemertes cantelli 38DS belonged apparently to its prey (according to BLAST search, it is an unknown sipunculid – GenBank MF 512129). Moreover, a COI sequence (GenBank MF 512130) of a similar sipunculid was detected in the specimen of S. cantelli 31DS through direct sequencing.’

Figures

Figure 3. A, Baseodiscus aff. marmoratus (Bürger, 1890) (voucher DNA, ICHUM 6322); B, Baseodiscus aff. maculosus (Bürger, 1895a) (voucher DNA, ICHUM 6324); C–E, Baseodiscus delineatus (Delle Chiaje, 1822-1829), ICHUM 6326; F, Baseodiscus cf. curtus (Hubrecht, 1879), ICHUM 6328; G, H, Baseodiscus urgorrii sp. nov., holotype, MCZ IZ-135319, entire body (G) and protruding proboscis (indicated by an arrowhead, H); I, Baseodiscus punnetti (Coe, 1904), specimen different from any voucher specimens in this study; J, K, Baseodiscus kakuii sp. nov., holotype, ICHUM 6334, anterior body (J) and