Marcus & Marcus, 1970
Upper: Hawaii - found under rocks on shallow subtidal reefs (about 1 meter depth) and in basaltic ledges and small caves at night at depths of 5-15 meters. Lower: Enewetak, Marshall Islands - usually under dead coral rocks at depths of 2-12 meters. Specimens were in the 25-40mm range. Photos: Sott Johnson.
The shape of the living animal is very similar to that of Berthellina citrina with an elongately oval mantle completely covering the foot, and rolled rhinophores and tentacular oral veil visible anteriorly. The mantle is soft with some raised wrinkles. It is translucent clear with a reddish brown tinge, more dense in some specimens than others. The mantle wrinkles show as a darker irregular pattern. The viscera show through the mantle as coloured patches. It grows to about 40mm long.
The gill has a smooth rachis. The internal shell is calcified, but very thin. It is relatively small [one-third adult body length] and is situated anteriorly above the viscera, as in Berthellina. This species is considered to be the sole member of distinct genus, closely related to Berthellina. To distinguishing features are an accessory denticle on each radular tooth and a large pedal gland. However studies by Willan (1984, 1987) have been unable to find this gland which was described by Marcus & Marcus (1970). Willam (1987) suggests the gland may be an artifact of preservation.
• Marcus, Er. & Marcus, Ev. (1970) Opisthobranch mollusks from the southern tropical Pacific. Pacific Science, 24(2): 155-179.
• Willan, R.C. (1984) The Pleurobranchidae (Opisthobranchia: Notaspidea) of the Marshall Islands, Central-West Pacific Ocean. The Veliger 27(1): 37-53, Figs 1-44.
• Willan, R.C. (1987) Phylogenetic systematics of the Notaspidea (Opisthobranchia) with reappraisal of families and genera. Am. Malacol. Union Bull., 5(2): 215-241.
Rudman, W.B., 2003 (April 6) Pleuredhera haraldi Marcus & Marcus, 1970. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/pleuhara
April 8, 2003
From: Scott Johnson
Here are three photos of Pleurehdera haraldi. The hn08 numbers are specimens photographed in Hawaii, and the e numbers from Enewetak, Marshall Islands. All these specimens were in the 25-40mm range. In Hawaii, I found them under rocks on shallow subtidal reefs (about 1 meter depth) and in basaltic ledges and small caves at night at depths of 5-15 meters. At Enewetak, they were usually under dead coral rocks at depths of 2-12 meters.
Johnson, S., 2003 (Apr 8) Pleurehdera haraldi from central Pacific. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/9614
Its good to see some photos of living animals of this species. There is certainly no major external feature to easily distinguish it from Berthellina or even Berthella. Your photo e191_1 with its head on the edge of the soft coral colony is tantalising, as we know nothing of its diet. Perhaps as you have shown forBerthellina citrina, cnidarians form part of its diet.