Cyerce kikutarobabai Hamatani, 1976

Moreno, Karina, Medrano, Sabrina, Gosliner, Terrence M., Wilson, Nerida G., Krug, Patrick J. & Valdés, Ángel, 2025, Phylogenetic systematics of the genus Cyerce Bergh, 1870 (Mollusca: Heterobranchia: Sacoglossa: Caliphyllidae) from the Pacific and Indian oceans with descriptions of nine new species, Zoological Journal of the Linnean Society 204 (1) : -

Cyerce kikutarobabai Hamatani, 1976

( Figs 26–28)

Cyerce kikutarobabai Hamatani 1976: 283–286 , pl. 1, figs 1A–C, 2A–C. Type locality: Yoron Island , Amami Islands, Japan.

Type material

Cyerce kikutarobabai — holotype untraceable (see: remarks), 1 Apr 1975, 9 mm in length.

Material examined

Okinawa, Ryūkyū Islands , Japan, 23 Apr 1992, 3 m depth, leg. B. Bolland, 1 specimen 5 mm preserved length ( CASIZ 086574 ) . Tulumben , Bali, Indonesia, 1 Oct 2001, leg. M. Miller, 2 specimens ( CASIZ 172614 ) . Nouméa , New Caledonia, 16 Sep 2022, 1 specimen 7 mm preserved length, leg. Luc Bourdil, dissected ( MNHN IM-2019-26210 ) ; 18 Sep 2022, 1 specimen, leg. Luc Bourdil (isolate 22 NC102 ) . Nouméa , New Caledonia, 10 m depth, 14 Oct 2019, leg. A. Doulas, 1 specimen 10 mm preserved length, dissected (isolate KM71 , MNHN IM-201926193 ) .

Range

Western Pacific Ocean ( Hamatani 1976, Rudman 2001, Nakano 2018, Gosliner et al. 2018; present study).

Description

External morphology: Body colour ochre, margin translucent white ( Fig. 26). Pericardium inflated, antero-dorsal, opaque white. Anal papilla located between right rhinophore and pericardium. Head colour translucent, with burgundy hue; darker burgundy mask-like patch surrounding eyes. Rhinophores long, translucent with burgundy hue, with few white spots concentrated near tips. Tentacles translucent with burgundy hue. Cerata inflated, obovate; pale cream, with dorso-medial reddish-brown patch; circular pale yellow to cream spots, irregularly sized, covering reddish-brown patch. Cerata margin outlined with yellow-orange band.

Internal morphology: Pharynx about 2.5 mm in length, buccal bulb smaller than pharyngeal pouch. Radula with 11 teeth in a 10-mm preserved length specimen ( MNHN IM- 201926193); 5 teeth on descending limb, 7 teeth on ascending limb ( Fig. 27A). Teeth moderately wide, slightly curved, about 200 µm in length, with blunt tips ( Fig. 27B). Two rows of ~20 rhomboidal denticles along either side of tooth. Size of denticles varies along tooth, smaller towards base and tip. Penial stylet short, about 100 µm in length, slightly curved, with oval opening, curved blunt tip (cup-like), located at opening of penis ( Fig. 28).

Ecology

Associated with green algae of the genus Halimeda .

Remarks

Hamatani’s (1976) original description of Cyerce kikutarobabai Hamatani, 1976 includes details of the external and internal morphology that closely resemble the specimens examined herein. Hamatani (1976) described the cerata of C. kikutarobabai as having a reddish-purple coloration (more intense towards the cerata margin), yellow-orange irregular round patches on each side of the cerata, and a yellow-orange band outlining the ceratal margin, all consistent with the cerata of specimens examined here. Moreover, Hamatani (1976) described the colour of the rhinophores and tentacles as reddish-purple, similarly observed in our specimens. However, Hamatani (1976) did not describe white spots on the rhinophores as observed in the material here examined. A reddish-purple pattern surrounding the eyes was also described by Hamatani (1976) and resembles the ‘masklike’ pattern on the head of our specimens. Hamatani (1976) did not describe a penial stylet for his specimens. However, our specimens possess a stylet, suggesting this trait could be variable or that the stylet was retracted into the tissue examined by Hamatani (1976). By internal and external morphology, C. kikutarobabai is distinct from all other Cyerce spp.

The holotype of C. kikutarobabai is untraceable and probably lost. It could not be found in the zoological collection of the Seto Marine Biological Laboratory (Tomoyuki Nakano, pers. comm.). According to Kazunori Hasegawa (pers. comm.), most of Hamatani’s type specimens were donated by his family to the Osaka Museum of Natural History. Currently the Hamatani collection is in the process of being fully transferred to the Osaka Museum, curated, and re-organized, but the holotype of Cyerce kikutarobabai has yet to be located at the time of the publication of the present paper.

In molecular phylogenetic analyses, C. kikutarobabai was recovered in a clade with the Mediterranean species C. graeca and C. cristallina (known also from the Western Atlantic). Notably, the external morphology of C. kikutarobabai and C. cristallina display some similarities: both species have maroon to purple rhinophores and heads with large white oval patches around the eyes, and translucent cerata edged in white with a prominent medial stripe or patch the same maroon to purple colour as the head. Cerata of both species are also flecked with small lightcoloured spots.