Fjordia lineata ( Loven , 1846) Loven, 1846

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 : 28-29

Fjordia lineata ( Loven, 1846) comb. n. Fig. 24

Aeolis lineata Lovén, 1846: 8.

Coryphella lineata : Thompson and Brown 1984 (pars.)

Flabellina lineata sensu Malmberg and Lundin 2015 (pars.): 88

Type material.

Original type material lost. Neotype, NTNU-VM-72483, 11 mm long (fixed) is designated here from the Svarte Jan, Idefjorden, Sweden, 06.06.2015, depth 22 m, coll. Mats Larsson, close to Lovén’s original type locality.

Material.

One specimen, ZMMU Op-403, 19 mm long (live), Norway, entrance of the Sognefjord, Gulen Dive Resort, 18.03.2015, depth 10-20 m, coll. Jørn Ari, Tina Malmgren. One specimen, ZMMU Op-406, 27 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. One specimen, ZMMU Op-506, 34 mm long (live), Norway, entrance of the Sognefjord, Gulen Dive Resort, 17.03.2015, depth 20 m, coll. T.A. Korshunova, A.V. Martynov. One specimen, ZMMU Op-506, 37 mm long (live), Norway, entrance of the Sognefjord, Gulen Dive Resort, 17.03.2015, 20 m depth, coll. T.A. Korshunova, A.V. Martynov. One specimen, ZMMU Op-507, 21 mm long (live), Norway, entrance of the Sognefjord, Gulen Dive Resort, 01.03.2014, depth 20 m depth, coll. T.A. Korshunova, A.V. Martynov. One specimen, ZMMU Op-508, 21 mm long (live), Norway, entrance of the Sognefjord, Gulen Dive Resort, 17.03.2015, 20 m depth, coll. T.A. Korshunova, A.V. Martynov.

Type locality.

Oslofjord, Norway.

Diagnosis.

Discontinuous notal edge, background colour translucent white, digestive gland diverticula pink, orange-brown to reddish-brown, apical parts of cerata with white pigment, along dorsal face of cerata runs thin straight or slightly curved line, thin opaque white lines on dorsal and lateral sides, rachidian tooth with up to seven distinct denticles delineate from central cusp, lateral teeth with up to 14 denticles on teeth edge, penis is a broad lobe.

Description.

External morphology (Fig. 24 A–E). Body elongate, graceful, laterally compressed. Foot narrow, tail moderate, anterior foot corners long. Oral tentacles long. Rhinophores long and slightly wrinkled, similar in length to oral tentacles. Dorsal cerata finger-shaped forming two to four indistinct clusters. Apices of cerata pointed. Distinct notum remains only below cerata clusters. Digestive gland diverticulum fills significant volume of the cerata. Anal opening on right side of body between first and second pair of dorsolateral processes. Reproductive openings lateral, below first pair of dorsolateral cerata on right side.

Colour (Fig. 24A). Background colour translucent white. Digestive gland diverticula orange-brown to salmon to bright red to dark brown, almost black when feeding on Bougainvillea . Thin continuous opaque white line runs over middle of dorsum from head to tail. Similar single thin median line runs on both lateral sides of the body. Rhinophores similar in colour to body; apical parts covered with faint opaque white pigment. Dorsal sides of oral tentacles covered with thin opaque white line. Along dorsal face of cerata runs thin straight or slightly curved line. Apical parts of cerata covered with opaque oblique ring of white pigment which connects to median cerata line. Cnidosac obscured by white pigment ring. Scattered small white dots over cerata absent.

Jaws (Fig. 24G, H). Masticatory process more than one-third as long as jaw body. Edge of masticatory processes bears ca. 70 denticles that continue to form several reduced rows of denticles on body of masticatory processes.

Radula (Fig. 24I). Radula formula: 17 × 1.1.1. Rachidian tooth horseshoe-shaped without evident cusp (Fig. 24I). Rachidian tooth bears six or seven well-defined separated long lateral denticles. Cusp indistinct and sunken below adjacent first lateral denticles. Lateral teeth (Fig. 24I) narrowly triangular with sharpened and attenuated outer process and between eleven and fourteen sharp long denticles on internal edge.

Reproductive system (Fig. 24 J–L). Diaulic. Hermaphroditic duct leads to convoluted ampulla of about two whorls. Vas deferens very short, no distinct prostate. Penial sheath large, wide. Penis is broad lobe (Fig. 24K). 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 the Tubularia indivisa and Ectopleura larynx colonies usually at depths of 10-40 m. Attacks and feeds on polyps of Tubularia , Ectopleura , Eudendrium , Bougainvillea and other athecate hydroids. Juveniles probably start to feed on species with smaller polyps. This species is abundant in some localities. Egg mass is irregular compressed spiral cord. Reproduction period from February to June; the larva is a planktotrophic veliger with an oval shell.

Distribution.

Confirmed specimens of F. lineata Northeast Atlantic, including Ireland, Great Britain, Norway (Oslofjord to Lofoten Islands) ( Odhner 1939; present study), Sweden ( Bohuslän region) ( Malmberg and Lundin 2015) western Mediterranean ( Thompson and Brown 1984, Trainito and Doneddu 2014).

Remarks.

Coryphella lineata in the traditional sense (e.g., Odhner 1939; Thompson and Brown 1984; Evertsen and Bakken 2005) is a genera complex (see below) according to both morphological and molecular data (Fig. 1). Lovén’s (1846) original description of Aeolis lineata is short and uninformative. In order to maintain the current usage of the specific name Fjordia lineata ( Lovén, 1846) a neotype is designated here (Fig. 24). The neotype was collected in shallow waters in the Idefjord on the south-eastern coast of Sweden, in the vicinity of the original type locality in the Bohuslän region ( Lovén 1846). All studied specimens shared the characteristic for this species of an expanded white pigment ring at the ceratal tip which is continued as a thin white line down the ceratal body. This feature persists both in subadult and fully mature specimens. The latter differ from subadults in having a broader body and pinkish body colour.