Hantazuia kimotoi, Korshunova & Fletcher & Martynov, 2025

Korshunova, Tatiana, Fletcher, Karin & Martynov, Alexander, 2025, The endless forms are the most differentiated-how taxonomic pseudo-optimization masked natural diversity and evolution: the nudibranch case, Zoological Journal of the Linnean Society 204 (4) : -

publication ID

https://doi.org/10.1093/zoolinnean/zlaf057

publication LSID

lsid:zoobank.org:pub:D09886E-5D7C-40D1-B86A-118A3ADE5773

persistent identifier

https://treatment.plazi.org/id/03EF87FE-FF8F-FFEF-FED9-FF05FC3CFBC5

treatment provided by

Plazi

scientific name

Hantazuia kimotoi
status

sp. nov.

Hantazuia kimotoi sp.nov.

( Figs 1, 8)

urn:lsid:zoobank.org:act:

Etymology: In honour of citizen scientist Nobuhiko Kimoto (木元伸彦), Japan, the founder of a comprehensive web-site ‘Nudibranchs of the world’ (世界のウミウシ), who most kindly helped us in observing and collecting nudibranchs.

Holotype: KM1068 , L = 13 mm (live), north-western Pacific , Japan, Honshu, Jogāshima Island waters, stones, 10–20 m depth, 14 August 2023, coll. Yugo Ikeda.

Paratype: KM1072 , L = 5 mm (live), north-western Pacific , Japan, Honshu, Jogāshima Island waters, stones, 10–20 m depth, 18 September 2023, coll. Yugo Ikeda.

Description

External morphology ( Fig. 8A–D, K, L) Body narrow. Foot and tail narrow, anterior foot corners moderate in length. Rhinophores similar in length to oral tentacles, smooth. Dorsal cerata finger-shaped to fusiform, forming up to about 20–25 small curved lobes with cerata in total (placed partly in a scallop-like pattern, if counting only the ceratal lobe-based groups, they will be correspondingly fewer in number) and separately placed cerata along dorsal edges, which are formed by a reduced discontinuous notal edge. Apices of cerata gradually pointed, with elongated cnidosacs. Digestive gland diverticulum fills significant volume of the cerata. Anal opening pleuroproctic on right side below middle ceratal lobes. Reproductive openings lateral, below first-second and third-fifth ceratal lobes/separate cerata.

Colour ( Fig. 8A–D, K, L) Background colour semi-transparent whitish to greyish. Cerata opaque yellowish to lemon-coloured (granulated when magnified) throughout most of the length with somewhat lighter bases. Cnidosacs in subapical parts of cerata similar in colour or slightly darker. Apical parts of cerata without opaque cap of white pigment, semi-transparent. Rhinophores covered with yellowish-whitish pigment over almost their entire length. The blackish ampulla, seminal receptacles, vas deferens and other ducts, as well as more lighter greyish thick prostate (with darker elements inside) shine through anterior part of dorsal side and are characteristically well visible in living specimens. Whitish to pinkish gonad shines through the mid and posterior parts.

Jaws ( Fig. 8G, H) Jaws oval-triangular. Edge of masticatory processes bears up to at least 17 denticles that may form compound row of thickened denticles comprised of some smaller tubercles.

Radula ( Fig. 8E, F, M) Radula formula in two specimens about 19 × 0.1.0. Central teeth considerably narrow, elongate-triangular, rather feather-shaped with short, narrow, commonly double cusps. Central teeth bear up to at least nine well-defined distinct, but denticles narrowly-arranged toward cusp. Lateral teeth absent.

Reproductive system ( Fig. 8I, J, N–P) Hermaphroditic duct leads to oval swollen ampulla. Vas deferens moderately long, narrow, convoluted, leads to very distinct, thick prostate. Penial sheath is oval. Penis is broadened conical, bears relatively short, slightly curved stylet. Oviduct connects through insemination duct into female gland complex. Proximal receptaculum seminis elongate. Distal receptaculum seminis present, oval, almost sessile on a short stalk.

Ecology: Shallow waters, stony habitats.

Distribution: In our material, present from the Pacific side of middle Japan (Honshu). But according to one GenBank sequence ( Fig. 1), quite paradoxically it also occurs in the Philippines, but that needs to be checked with more new material. Potentially may reliably occur in other parts of Honshu and more southern main Japanese Islands.

Remarks: Hantazuia kimotoi sp. nov. is externally similar to Hantazuia yugoikedai sp. nov., but reliably differs from it by the shape of its copulative stylet, which is significantly shorter and less curved ( Fig. 8I, J, N–P). The potential external difference between H. kimotoi sp. nov. and H. yugoikedai sp. nov. is that the latter has somewhat shorter anterior foot corners and is possibly larger in length at the adult stage ( Fig. 8B, C), but this needs to be checked further. Uncorrected COI p -distance within the Hantazuia kimotoi sp. nov. clade is 1.22%. The COI uncorrected p -distances between the H. kimotoi sp. nov. clade and the H. yugoikedai sp. nov. clade are 12.3%–12.8%, between the H. kimotoi sp. nov. clade and the H. imagawai sp. nov. clade they are 12.8%–13.1%.

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