Fjordia chriskaugei, Korshunova, Tatiana, Martynov, Alexander, Bakken, Torkild, Evertsen, Jussi, Fletcher, Karin, Mudianta, I Wayan, Saito, Hiroshi, Lundin, Kennet, Michael Schroedl, & Picton, Bernard, 2017

Korshunova, Tatiana, Martynov, Alexander, Bakken, Torkild, Evertsen, Jussi, Fletcher, Karin, Mudianta, I Wayan, Saito, Hiroshi, Lundin, Kennet, Michael Schroedl, & Picton, Bernard, 2017, Polyphyly of the traditional family Flabellinidae affects a major group of Nudibranchia: aeolidacean taxonomic reassessment with descriptions of several new families, genera, and species (Mollusca, Gastropoda), ZooKeys 717, pp. 1-139 : 25-28

Fjordia chriskaugei sp. n. Fig. 23

Coryphella lineata (auctt.)

Flabellina lineata sensu, part.: 88.

Non Aeolis lineata Lovén 1846: 8.

Type material.

Holotype, ZMMU Op-477, 45 mm long (live), Norway, entrance of the Sognefjord, Gulen Dive Resort, 19.03.2015, depth 20 m, coll. T.A. Korshunova, A.V. Martynov. 1 paratype, ZMMU Op-402, 28 mm long (live), Norway, entrance of the Sognefjord, Gulen Dive Resort, 18.03.2015, depth 10-20 m, coll. T.A. Korshunova, A.V. Martynov. 1 paratype, ZMMU Op-404, 28 mm long (live), Norway, entrance of the Sognefjord, Gulen Dive Resort, 16.03.2015, depth 20 m, coll. T.A. Korshunova, A.V. Martynov. 1 paratype, ZMMU Op-405, 30 mm long (live), Norway, entrance of the Sognefjord, Gulen Dive Resort, 16.03.2015, depth 20 m, coll. T.A. Korshunova, A.V. Martynov. 1 paratype, ZMMU Op-412, 42 mm long (live), Norway, entrance of the Sognefjord, Gulen Dive Resort, 17.03.2015, depth 10-20 m, coll. T.A. Korshunova, A.V. Martynov. 1 paratype, ZMMU Op-499, Achill Island, Co. Mayo, Ireland, 06.04.2015, coll. B.E. Picton.

Type locality.

Gulen Dive Resort, Norway.

Etymology.

In honour of Christian Skauge (Gulen Dive Resort and Scubapixel), the organiser of the "Nudibranch Safari" and our great friend, who first noticed the heterogeneity of the traditional C. lineata in the field in Norway, including photographic records.

Diagnosis.

Discontinuous notal edge, background colour translucent white, digestive gland diverticula pink, orange-brown to reddish-brown, apical parts of cerata with white pigment, usually one to several punctuated fine white lines run along dorsal face of cerata, thin opaque white lines on dorsal and lateral sides, rachidian tooth with up to 10 distinct denticles delineate from central cusp, lateral teeth with up to eleven denticles on teeth edge, penis is a broad lobe.

Description.

External morphology (Fig. 23 A–E). Body relatively narrow. Foot and tail moderate, anterior foot corners long. Oral tentacles long. Rhinophores ca. 1.5 times longer than oral tentacles, slightly wrinkled. Dorsal cerata finger-shaped to fusiform, forming several clusters along dorsal edges. Apices of cerata gradually pointed, with elongate cnidosac. Distinct notal edge remains mostly below cerata clusters. Digestive gland diverticulum fills significant volume of cerata. Anal opening on right side below second large cluster of cerata. Reproductive openings lateral, below first anterior cluster of cerata.

Colour (Fig. 23A, D). Background colour translucent white. Digestive gland diverticula pale pink, orange-brown to reddish-brown depending on locality and diet. Pinkish oral tube, oesophagus, hindgut, and gonads shine through dorsal sides. Thin opaque zigzag white line runs along middle of whole dorsum from head to tail. Similar single thin median line runs on both lateral sides of the body. Rhinophores background colour similar to body; along dorsal side of rhinophores runs a thin white line; apical white pigment absent. Dorsal sides of oral tentacles covered with thin opaque white line. One to several punctuated fine white lines run along dorsal face of cerata, sometimes absent. Apical parts of cerata without any opaque cap of white pigment.

Jaws (Fig. 23G, H). Masticatory process more than one-third as long as jaw body. Edge of masticatory processes bears ca. 60 denticles that continue to form several reduced rows of denticles on body of masticatory processes.

Radula (Fig. 23I). Radula formula: 13 × 1.1.1. Rachidian tooth elongate-triangular with short narrow cusp of less than 1/3 of tooth length (Fig. 23I). Rachidian tooth bears between seven and ten well-defined separated long lateral denticles not adpressed towards the cusp. Cusp delineated from adjacent first lateral denticles. Lateral teeth (Fig. 23I) broadly triangular with obtuse and considerably attenuated posteriorly outer process and between eight and eleven sharp long denticles on internal edge.

Reproductive system (Fig. 23 J–L). Diaulic. Hermaphroditic duct leads to convoluted ampulla of about two whorls. Vas deferens very short, attached to dorsal side of penial sheath, no distinct prostate. Penial sheath large, wide. Penis is broad lobe (Fig. 23L). Oviduct connects through insemination duct into female gland complex. Vagina short and indistinct. Proximal receptaculum seminis large, oval, swollen. Distal receptaculum seminis present.

Ecology.

Associates with Tubularia colonies usually at depth 20-40 m. Attacks and feeds on polyps of Tubularia indivisa L., 1758. Juveniles probably start to feed on Eudendrium spp. or other smaller athecate hydroids. This species is abundant in some localities. Egg mass narrow cord; forms irregular, compressed pink or off-white spirals. Reproduction period from February to June; larva planktotrophic veliger with oval shell.

Distribution.

Northeast Atlantic, including Ireland, Great Britain (Scotland, England, Wales), Norway.

Remarks.

Fjordia chriskaugei sp. n. is distinguished morphologically from F. lineata ( Lovén, 1846) s. str. (Fig. 24) by faint dotted lines on the dorsal surface of the cerata, the complete absence of the apical white cap, by rhinophores longer than oral tentacles, and by the distinct cusp of the rachidian teeth which is placed above the adjacent lateral denticles. Molecular analysis corroborates the morphological data (see Discussion) showing F. chriskaugei sp. n. as a species distinct from F. lineata s. str. (Fig. 1). Thompson and Brown (1984, pl. 27) and Picton and Morrow (1994, p. 95) illustrate this species as Coryphella lineata and their descriptions are a composite of the two species. The majority of specimens demonstrate significant uniformity in the body shape and colour. In some specimens from Ireland the irregular white lines on the cerata can be completely absent.