On a new Ercolania Trinchese, 1872 (Opisthobranchia, Sacoglossa, Limapontiidae) living within Boergesenia Feldmann, 1950 (Cladophorales), with notes on anatomy, histology and biology

A new sacoglossan species, belonging to the genus Ercolania Trinchese, 1872 is described. E. kencolesi sp. nov. has a similar biology as E. endophytophaga Jensen, 1999. Both are living within syncytial algal tubes of members of the Siphonocladales, E. kencolesi sp. nov. in Boergesenia forbesii and E. endophytophaga in Struvea plumosa. Assignment to the genus Ercolania is possible on the base of the cerata, which are round in cross-section, the digitiform rhinophores, sabot-shaped teeth and the presence of a penial stylet. The new species can be easily distinguished from E. endophyto-phaga, by the teeth with a prominent cusp, as well as other Ercolania species, by its unique colouration and its peculiar association to the food alga Boergesenia. Feeding, copulation, egg masses and development are noted. Differences in development further strengthen the distinction of E. kencolesi to E. endophytophaga. Measurement of photosynthetic activity of incorporated chloroplasts during several days clearly shows that chloroplasts are digested.

Effect of growth rate of the food alga on the growth/ingestion efficiency of a marine herbivore

The chlorophycean alga, Brachiomonas submarina var. pulsifera Droop, was grown in two bacteria-free chemostats, differing only in the amount of light each received. Investigations were made into the changes in biochemical composition and calorific value of the cells when they were grown at different growth rates. This information was used to help to explain changes in the growth efficiency of the rotifer Brachionus plicatilis Miiller, grown in a bacteria-free chemostat which was linked to one of the algal chemostats, the algae being supplied as the source of food.