Paracoryphellidae M. C. Miller, 1971

Ekimova, Irina, Valdés, Ángel, Stanovova, Maria, Mikhlina, Anna, Antokhina, Tatiana, Neretina, Tatiana, Chichvarkhina, Olga & Schepetov, Dimitry, 2021, Connected across the ocean: taxonomy and biogeography of deep-water Nudibranchia from the Northwest Pacific reveal trans-Pacific links and two undescribed species, Organisms Diversity & Evolution (New York, N. Y.) 21 (4), pp. 753-782 : 772-774

Family Paracoryphellidae M. C. Miller, 1971

hypothesis of genus Ziminella, Bayesian inference, concatenated dataset of four markers (COI+16S +H3+ 28S), species-level clades and outgroups are collapsed to a single branch, except target spe - cies. Numbers above branches indicate posterior probabilities from Bayesian inference, numbers below branches, bootstrap support from maximum likelihood. C, molecular phylogenetic hypothesis of genus Zeusia , maximum likelihood, concatenated dataset of three markers (COI +16S +H3), species-level clades and outgroups are collapsed to a single branch, except target species. Numbers above branches indicate posterior probabilities from Bayesian inference, numbers below branches, bootstrap support from maximum likelihood

Genus Ziminella Korshunova, Martynov, Bakken, Evertsen, Fletcher, Mudianta, Saito, Lundin, Schrödl & Picton, 2017

Ziminella vrijenhoeki Valdés, Lundsten & N. G. Wilson, 2018

( Fig. 15 )

Material studied: MIMB 42255 , Bering Sea, 60°50′3.5″ N, 174°22′21.4″ E, depth 660 m, July 03, 2018 , R / V Akademik Lavrentyev, 1 specimen .

External morphology ( Fig. 15A–C ): Body length 21 mm. Body elongate, broad, with well-developed continuous notal edge. Cerata in dense indistinct rows. Oral tentacles short, wide. Foot corners short and wide. Rhinophores conical, smooth. Anal opening dorso-lateral, posterior to pericardium. Reproductive opening under notal edge on right anterior part of body.

Color ( Fig. 15A–C ): Dorsal side of body, head and oral tentacles light orange. Rhinophores intense orange. Digestive gland diverticula grayish orange to light brown. Cnidosac region dotted by white pigment. Dorsal cerata with orange subapical rings, lateral cerata lack this pigmentation.

Anatomy: Buccal mass large, muscular. Jaws elongate triangular plates, with up to 15 rows of rounded denticles on masticatory border ( Fig. 15D, E ). Radular formula 25× 1.1.1 ( Fig. 15F ). Rachidian tooth with large central conical cusp and up to eight denticles on each side ( Fig. 15G, H ). Lateral teeth triangular, narrow, with pointed cusp and up to 14 denticles on inner side ( Fig. 15I ). Reproductive system diaulic. Ampulla very long, convoluted, forming loops. Prostatic vas deferens long and convoluted. Penis slightly curved, elongate. Receptaculum seminis oval.

Molecular data: On our phylogenetic reconstruction of four markers (COI, 16S, H 3, 28S) here studied specimen forms a single clade with the type specimen of Z. vrijenhoeki (PP= 1; ML = 100) ( Fig. 14B ). This species is sister to the rest of Ziminella species in the ML analysis (ML = 100), but shows unresolved relationships with both Ziminella and Chlamylla in the BI analysis.

Biology: This species was found in seep communities with Calyptogena as a dominant species. Local seepage occurs through cracks in carbonate plates; such places are marked with thick bacterial mats and Calyptogena settlements. In the vicinity, several large buccinid gastropods, pogonophorans, and terebellid tubeworms were noted and various small ophiuroids are also an abundant component of the community. Cnidarian fauna is represented by abundant soft coral Caryophyllia and rare Hormatiidae anemones.

Distribution: Known from the deep sea off California ( Valdés et al.,2018) and from the Bering Sea (present study).

Superfamily Aeolidioidea Gray, 1827

Family Aeolidiidae Gray, 1827

Genus Zeusia Korshunova, Zimina & Martynov, 2017 Zeusia herculea ( Bergh, 1894)

= Aeolidia grandis Volodchenko, 1941 syn. nov.

( Fig. 16 )

Material studied: MIMB 42254 , Bering Sea, 61°10′40.1″ N, 174°52′14.9″ E, depth 536 m, June 28, 2018 , R / V Akademik Lavrentyev, 1 specimen .

External morphology ( Fig. 16A–C ): Body length 29 mm. Body wide, possessing numerous elongate, flattened cerata in distinct dense rows. Smooth conical oral tentacles. Rhinophores slightly tuberculated. Anus pleuroproctic. Genital openings on right side, at 1/3 of body length.

Color ( Fig. 16A–C ): Body, head, oral tentacles, and foot bright orange. Rhinophores intense orange, with lighter tubercles. Cerata semitransparent, with brownish digestive gland seen through body wall and numerous white dots. Cnidosac region dotted by white pigment, and wide orange ring below. Lateral cerata lack orange pigmentation.

Anatomy: Buccal mass large, muscular. Jaws elongate oval, lacking denticles on masticatory border. Radular formula 23×0.1.0 ( Fig. 16D, E ). Rachidian tooth wide, lacking central cusp, with up to 25 long sharp denticles on each side ( Fig. 16F, G ). Reproductive system diaulic. Ampulla long, convoluted. Prostatic vas deferens long and winding, forming several loops. Penile sheath broad. Receptaculum seminis oval.

Molecular data: On the three-marker phylogenetic tree (COI, 16S, H3) our specimen forms a single clade with Z. herculea (PP= 1; ML = 100), collected in the NE Pacific, near the type locality. Zeusia herculea clade is sister to Z. hyperborea Korshunova, Zimina & Martynov, 2017 (PP = 1; ML = 100). Within the family Aeolidiidae , the genus Aeolidia is sister to Zeusia (PP=1; ML = 100).

Biology: This specimen was found in an ophiuroid community, far from methane seeps. Crustacean benthic fauna is a common component, with many hermit crabs, shrimps, and other decapods found in the area. Large buccinid gastropods, Myxoderma sea stars and Achorax bivalves also occur. Cnidarian fauna is represented by numerous species of Sagartiidae , Liponema and rarely large anemones.

Distribution: North Pacific deep-sea areas from California to the Sea of Okhotsk ( Korshunova et al., 2017b; Valdés et al., 2018; Volodchenko, 1941; present study).

Figures

Fig.15 Ziminella vrijenhoeki Valdés et al. 2018, MIMB 42255, external morphology and SEM micrographs of internal morphology. A, dorsal view. B, ventral view. C, living specimen in natural environment. D, jaw masticatory border. E, details of denticulation of

Fig. 14 Results of molecular analysis of different aeolid groups. A, genus Cuthona, COI haplotype network produced with TCS method in PopART. Colors of circles refer to the geographic origin of each haplotype. The relative size of circles is proportional to the number of sequences of that same haplotype. B, molecular phylogenetic hypothesis of genus Cuthona, maximum likelihood, concatenated dataset of three markers (COI+16S+H3), species-level clades and outgroups are collapsed to a single branch, except Cuthona and Bohuslania species. Numbers above branches indicate posterior probabilities from Bayesian inference, numbers below branches, bootstrap support from maximum likelihood. C, molecular phylogenetic

Fig. 16 Zeusia herculea (Bergh, 1894), MIMB 42254, external morphology and SEM micrographs of internal morphology. A, dorsal view. B, ventral view. C, living specimen in natural environment. D, posterior radular portion. E, anterior radular portion. F, G,