Goniobranchus rubrocornutus (Rudman, 1985)

Description

Mantle translucent creamy white with a broad orange band right at the edge. Just inside the orange border is an irregular red band that thickens and thins to give a wavy appearance, sometimes broken into red patches. Inside the red band is a thin opaque-white line, and inside that a broad opaque-white band of dendritic mantle glands. Rhinophore stalk almost transparent; the lamellae of the club are red — the source of the species' name. Gill lamellae also red. Underside white. Body length 6-13 mm preserved.

Distribution

Type locality is Hoi Ha, Flynn Point, Hong Kong (3 m depth, April 1982). Originally recorded in 1985 from the Marshall Islands (Bikini Atoll), Hong Kong, the Great Barrier Reef (Lizard Island), and from Japan (Baba, 1938, recorded as Glossodoris marginata). Subsequent records extend to Australia, Malaysia, the Philippines, Palau, and American Samoa.

Etymology

The specific epithet rubrocornuta is a Latin compound of ruber (red) and cornu (horn), referring to the species' characteristic red rhinophores (verbatim from the original description).

Remarks

Originally described as Chromodoris rubrocornuta and later transferred to Goniobranchus. Closely resembles Goniobranchus fidelis, but is distinguished by (1) red (not black) rhinophores and gills and (2) the absence of reddish-purple prolongations into the central white field. Also similar in colour pattern to Goniobranchus latus (Risbec, 1928) and to Thorunna purpuropedis described in the same paper.

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References

• Glossodoris marginata, Baba K. (1938). Opisthobranchia Of Kii, Middle Japan. Journal of the Faculty of Agriculture, Kyushu University. 6(1): 1-19. https://doi.org/10.5109/22587
• ウチナミシラヒメウミウシ（新称）, 中野理枝. (2004). 本州のウミウシ. ラトルズ.
• ウチナミシラヒメウミウシ（新称）, 小野篤司. (2004). 沖縄のウミウシ. ラトルズ.
• Goniobranchus rubrocornutus, Johnson R.F. & Gosliner T.M. (2012). Traditional taxonomic groupings mask evolutionary history: a molecular phylogeny and new classification of the chromodorid nudibranchs. PLoS ONE 7(4): e33479.
• Goniobranchus rubrocornutus, Terrence Gosliner, Ángel Valdés and David Behrens. (2015). Nudibranch and Sea Slug Identification Indo-Pacific. New World Pubns Inc.
• Goniobranchus rubrocornutus, Soong G.Y., Bonomo L.J., Reimer J.D. & Gosliner T.M. (2022). Battle of the bands: systematics and phylogeny of the white Goniobranchus nudibranchs with marginal bands (Nudibranchia, Chromodorididae). ZooKeys. 1083: 169-210. https://doi.org/10.3897/zookeys.1083.72939