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on food sponge

with egg mass

sp. #1

Goniobranchus sp. #1
Maximum size:  50 mm (Kay & Young, 1969).

Identification:  This is a broad, flattened species with a white notum densely reticulated in red, a yellow marginal band, yellow rhinophores and orange-lined gills. The notum is decorated by a series of enlarged, dome-shaped pustules with violet-red tips. The latter feature distinguishes it from the similar appearing Goniobranchus petechialis and Goniobranchus sp. #5.

Natural history:  Goniobranchus sp. #1 is commonly seen in moderately protected to exposed rocky habitats at depths of 6-60 m (20-197 ft). It is nocturnally active but may also be found under rocks, crawling on sand, or resting in the open on shaded cliffs during the day. Scott Johnson reports it apparently feeding on a white sponge. It lays a light peach egg mass and probably feeds on a yellow sponge.

Distribution:  Big Island, Maui, Molokai, Oahu, Kauai and Niihau: widely distributed in the Indo-Pacific.

Taxonomic notes:  Although labeled in various sources on-line as a form of Goniobranchus tinctoria, this appears to be a distinct species based on the enlarged hemispherical pustules on the notum, its solid-yellow rhinophores and its nocturnal habits. It is listed as Chromodoris petachialis in Bertsch & Johnson, 1981, Kay, 1979 and Kay & Young, 1969. Although Kay, 1979 suggests that it was first reported from Hawaii in Pease, 1860 as Doris reticulata, it seems more likely that that name refers to Sclerodoris sp. #1, instead. Therefore, it was probably first recorded in Hawaii from Ala Moana, Oahu in Dec., 1961. (Kay & Young, 1969) It's listed as Chromodoris sp. 1 and referred to as the "red-spotted nudibranch" in Hoover, 1998 & 2006.

Photo:  PF: Makena, Maui; 2007.

Observations and comments:

Note 1:  ( )
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