February 11, 2005
From: Bill Rudman
To accompany the Fact Sheet on Phestilla panamica, here are some SEM photos of the radula. This species has many similarities to the widespread Indo-west Pacific species Phestilla lugubris, which also feeds on species of the coral Porites. There appear to be consistent differences in radular morphology.
PHOTOS: SEM photos of the radula of Phestilla panamica (upper right, lower right - 17 mm long preserved) and Phestilla lugubris (lower left - 8 mm long alive). Scale bars = 20 µm. Photos: G. Avern.
In P. lugubris each tooth has five or six large denticles on each side of the central cusp. [see radula of coral-feeders]. The cusp always further forward than the denticles while in P. panamica there can be up to ten denticles on each side and the central cusp is shorter than the denticles. Specimens of P. lugubris I have examined from East Africa, Indonesia and Australia show no difference in tooth morphology. In similar sized animals, P. panamica has more teeth in the radular ribbon than P. lugubris. Two 24 mm long preserved animals of P. panamica had 46 and 52 teeth while a 25 mm long preserved specimen of P. lugubris had only 33 teeth. The largest number of teeth I have counted in P. lugubris was 39 in a 42 mm long live animal.
Rudman, W.B. (1982) A new species of Phestilla; the first record of a corallivorous aeolid nudibranch from tropical America. Journal of Zoology, London, 198: 465-471.
Rudman, W.B., 2005 (Feb 11) Radula of Phestilla panamica. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/12287