Hantazuia imagawai, Korshunova & Fletcher & Martynov, 2025
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-FFEE-FC0F-FBE1FE62F920 |
treatment provided by |
Plazi |
scientific name |
Hantazuia imagawai |
status |
sp. nov. |
Hantazuia imagawai sp.nov.
( Figs 1, 9)
urn:lsid:zoobank.org:act:
Etymology: In honour of citizen scientist Kaoru Imagawa (今 川 郁), Japan, the chief manager of the Ocean Blue dive club in Okinawa, who greatly contributed to the present study by observing and collecting nudibranchs.
Holotype: KM1059 , L = 10 mm (live), Japan, Okinawa, Arasaki , stones, 5 m depth, 30 October 2021, coll. Kaoru Imagawa.
Description
External morphology ( Fig. 9A–C) 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 15–20 small curved lobes with cerata in total (placed partly in a scallop-like pattern, if counting only the ceratal lobe-based groups, there will be correspondingly fewer in number) and separately placed cerata along dorsal edges, which are formed by a reduced discontinuous notal edge ( Fig. 9A–C). 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. 9A, C) Background colour semi-transparent dark greyish. Cerata distinctly zoned—opaque white for approximately two-thirds of their length and orange brownish apically. Rhinophores covered with milky-whitish pigment over almost their entire length. Apical parts of cerata without opaque cap of white pigment. The blackish ampulla shines through the anterior part of the dorsal side and is characteristically well visible in living specimens. Blackish and whitish gonad shines through the mid and posterior parts.
Jaws ( Fig. 9F, G) Jaws oval-triangular. Edge of masticatory processes bears up to at least 26 denticles that may form compound row of thickened denticles comprised of some smaller tubercles.
Radula ( Fig.9D, E) Radula formula in holotype about 12 × 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 about 10 well-defined distinct denticles, but narrowly-arranged toward cusps. Lateral teeth absent.
Reproductive system ( Fig. 9H–J) Hermaphroditic duct leads to oval, relatively large swollen ampulla. Vas deferens moderately long, narrow, somewhat convoluted, leads to very distinct, thick prostate. Penial sheath is oval. Penis is broadened conical, bears short, very slightly curved/almost straight stylet. Oviduct connects through insemination duct into female gland complex. Proximal receptaculum seminis elongate. Distal receptaculum seminis present, rather rounded, almost sessile on a short stalk.
Ecology: Shallow waters, stony habitats.
Distribution: In our material, present from the tropical part of Japan in Okinawa Island. Potentially may occur in other parts of the tropical regions of Japanese Islands and toward the Philippines.
Remarks: Hantazuia imagawai sp. nov. externally differs from both Hantazuia yugoikedai sp. nov. and Hantazuia kimotoi sp. nov. by its paler brownish, rather than yellowish, body and ceratal coloration, and further H. imagawai sp. nov. also reliably differs from both H. yugoikedai sp. nov. and H. kimotoi sp. nov. by the shape of its copulative stylet, which is significantly shorter and almost straight, only rather slightly curved ( Fig. 9H, I). The COI uncorrected p -distances between the Hantazuia imagawai sp. nov. clade and the H. yugoikedai sp. nov., clade are 12.3%–12.8%, and between the H. imagawai sp. nov. clade and H. kimotoi sp. nov. clade are 12.8%–13.1%.
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