Thorunna purpuropedis Rudman & S. Johnson, 1985

Description

Mantle purplish white with a broad orange marginal band (the inner half of the band is more opaque). Just inside the orange border runs an irregular red line that thickens and thins, giving in places the appearance of a row of red spots. Rhinophore stalks transparent; clubs with a whitish core and red lamellae. Gills watery red, deeper opaque at the edges. The foot is pale purple — the source of the species' name — deepening posteriorly and on the oral tentacles. Body elongate with a relatively narrow mantle margin, the anterior edge held horizontally and the foot folded down so that the animal appears spatulate. Seven simple gills wave rhythmically. Holotype 10 mm long alive; paratype 4 mm preserved.

Distribution

Type locality is the lagoon side of Ikuren Island, Enewetak Atoll, Marshall Islands (under a dead coral block, 8 m, August 1981, collected by S. Johnson). Originally known only from Enewetak Atoll; subsequent records also from Japan.

Etymology

The specific epithet purpuropedis is a Latin compound of purpureus (purple) and pes (foot), referring to the pale purple foot of the species (verbatim from the original description).

Remarks

The co-author Mr S. Johnson collected at Enewetak Atoll and contributed partial descriptive material on this species (and on Chromodoris galactos), which Rudman incorporated as a co-authored treatment in this comparative review. Although the colour pattern resembles Goniobranchus fidelis, Goniobranchus rubrocornutus (described in the same paper), and Goniobranchus latus, the species clearly belongs in Thorunna on radular, reproductive, and gill characters. The closest in colour is Goniobranchus latus, but Thorunna purpuropedis is distinguished by its purple (not white) foot and red (not white) rhinophores.

---

References

• Thorunna purpuropedis, 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.
• Thorunna purpuropedis, Terrence Gosliner, Ángel Valdés and David Behrens. (2015). Nudibranch and Sea Slug Identification Indo-Pacific. New World Pubns Inc.
• クチバイロウミウシ（新称）, 中野理枝. (2018). 日本のウミウシ. 文一総合出版.