Samla takashigei, 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 : 58

Samla takashigei sp. n. Fig. 47

Type material.

Holotype, ZMMU Op-530, 26 mm long (live), Japan, Osezaki, 11.09.2016, depth 10-15 m, coll. T.A. Korshunova, A.V. Martynov.

Type locality.

Osezaki, Japan.

Etymology.

Named in honour of Hiroshi Takashige (Tokyo), esteemed diver who is very fond of natural history and provided invaluable help during field collection in Osezaki, Japan.

Diagnosis.

Considerably reduced notal edge, forming several slightly elevated rows, background colour whitish with bluish hue, digestive gland in cerata light brownish, subapical parts of cerata orange-brownish, apical parts of cerata without white pigment, rachidian tooth with up to nine distinct denticles, slightly adpressed to central cusp, lateral teeth with up to eight denticles, penis conical.

Description.

External morphology (Fig. 47 A–E). Body narrow. Foot and tail narrow, anterior foot corners long. Rhinophores ca. six times shorter than extremely long oral tentacles, annulated. Dorsal cerata finger-shaped to fusiform, forming eight slightly elevated rows 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 the cerata. Anal opening pleuroproctic on right side between first and second ceratal rows. Reproductive openings lateral, below first anterior cluster of cerata.

Colour (Fig. 47A). Background colour whitish with bluish hue. Digestive gland diverticula light brownish. Rhinophores background colour similar to body. Subapical parts of cerata brighter orange–brownish. Cerata covered with opaque white pigment throughout most of the length. Apical parts of cerata without opaque cap of white pigment.

Jaws (Fig. 47F, G). Masticatory process more than one-third as long as jaw body. Edge of masticatory processes bears approximately 31 sharp denticles that form main single row of denticles on body of masticatory processes.

Radula (Fig. 47H). Radula formula: 19 × 1.1.1 (26 mm). Rachidian tooth elongate-triangular with short narrow cusp of less than 1/3 of tooth length (Fig. 47H). Rachidian tooth bears seven to nine well-defined separated long lateral denticles slightly adpressed towards cusp. Cusp is compressed by adjacent first lateral denticles. Lateral teeth (Fig. 47H) broadly triangular with obtuse and very attenuated posteriorly outer process, bear between six and eight sharp denticles. Some denticles can be forked or even triple.

Reproductive system (Fig. 47I, J). Diaulic. Hermaphroditic duct leads to convoluted ampulla of about two whorls. Vas deferens long, S-shaped, no distinct prostate. Penial sheath is narrow. Penis is narrow conical. Oviduct connects through insemination duct into female gland complex. Vagina short and indistinct. Proximal receptaculum seminis oval, swollen. Distal receptaculum seminis present, small.

Ecology.

Shallow waters, stony habitats.

Distribution.

Pacific side of middle Japan (Honshu).

Remarks.

From all known species of the genus Samla , S. takashigei sp. n. differs by colour pattern and details of the radular teeth and these morphological differences are robustly supported by molecular data (Fig. 2). The three specimens examined demonstrate significant uniformity in the body shape and colour. Our specimens from Vietnam (Fig. 46) are consistent morphologically with the type species of the genus Samla , S. bicolor (Kelaart, 1858) and its recognised synonym S. annuligera Bergh, 1900, according to the original descriptions ( Kelaart 1858; Bergh 1900b) and differ considerably from the Japanese S. takashigei sp. n. However, more species in the S. bicolor species complex are clearly present in the Indo-West Pacific according to the present phylogenetic analysis (Fig. 1); these will need attention in a further study.

Uncorrected p-distances of the mitochondrial barcode marker (COI) between Luisella babai and Samla species range between 19.0-21.0%, supporting the genus Luisella as a separate genus from Samla within the family Samlidae .