Home Acknowledgments Conventions Glossary Maps References Links Articles Thumbnails Species list Family Next species _______________   Additional Photos   underside   young, < 10 mm   young, about 12 mm   dark   shell   probable egg mass _______________   GALLERY	Pleurobranchus cf. peroni Cuvier, 1804   Maximum size:  about 75 mm (Hoover, 2006). Identification:  The notum of this species is covered with rounded tubercles, some of which are distinctly darker. The lighter creases between the tubercles give it a reticulated appearance. The background color ranges from light orange to dark wine-red. In the latter animals, the contrasting dark tubercles may be difficult to see. Very young animals are reticulated with white lines, lack darker tubercles and have violet tipped rhinophores. With growth, the lines disappear, scattered tubercles darken and the violet tips disappear. It can be distinguished from Pleurobranchus albiguttatus by its larger, more rounded tubercles and its contrasting dark tubercles. Natural history:  Pleurobranchus cf. peroni is a common nocturnal species found in moderately exposed to highly exposed rocky habitats and in Halimeda kanaloana beds. It occurs in tide pools and subtidally to depths of 18 m (59 ft). It contracts its rhinophores rhythmically while crawling and lays a cream, spiral egg mass with a frilly margin. Distribution:  Big Island, Maui, Oahu, Kauai, French Frigate Shoals, Midway and Kure; probably also known from Reunion and Japan. Taxonomic notes:  This is the species listed as Pleurobranchus sp. in Bertsch and Johnson, 1981 and Pleurobranchus sp. 1/Pleurobranchus sp., in Hoover, 1998 & 2006. It is referred to as the "polygon pleurobranch" in Hoover, 1998 & 2006. It differs from Pleurobranchus peroni as illustrated on the Sea Slug Forum in having proportionately larger tubercles and less white pigment in juveniles. (Note 1) It was probably first reported from Hawaii in Pease, 1860 (as Pleurobranchus reticulatus) and Pleurobranchus violaceus, Pease, 1864 may also be a synonym. Although this species matches the description of Pleurobranchus peronii in Kay, 1979, the photo of that species is actually of the dark form of P. albiguttatus. Photo:  Michelle White: about 55 mm: Mala Wharf, Maui; January 1, 2009. Observations and comments: Note 1:  Both juvenile and mature animals comparable to the Hawaiian specimens are known from Reunion in the Indian Ocean. Some mature animals from Japan also have comparably large tubercles (though they retain white on the notum, unlike those from Hawaii). That suggests that both the "large-tubercle form" and the "small-tubercle form" typically illustrated under the name Pleurobranchus peroni are broadly sympatric in the Indo-Pacific and readily distinguishable (particularly as juveniles). The "small tubercle form" has not yet been found in Hawaii. Assuming that they do represent two distinct species, examination of the type material may be needed to establish the identity of the "real" P. peroni.
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