Crepidula dilatata (Gastropuda, Calyptraeidae) truly living in the SW Atlantic.

PENCHASZADEH, P. E.; PASTORINO, G.; CLEDÓN, M.

Charleston

Encuentro; 68th Meeting of American Malacological Society; 2002

Crepidula fecunda Gallardo, 1979, was described from Bahía Chinquihu.(41°3I'S-73°03'W) in the Chilean Pacifico C. dilatata Lamarck, 1822, idifferentiated by its direct development and the presence of embryos consumir»nurse eggs. Adult morphological features are identical. Therefore, earlier recordreferring to the presence of C. dilatata in the Atlantic coast of South America nee,validation. The type locality of C. dilatata remains unknown but the Western coasof South America as a probable type locality has been mentioned in a commentelist of the types from Larnarcks collection. Egg capsules and adult, males anfernales were collected from Bahía Ensenada, Ushuaia (~55°S) to Golfo Nuev(-42°30'S) in Chubut province. Collections were during February 2000. Wstudied more than 100 brooding females. Most fernales were brooding egg rnasseat advanced stages of embryonic development, containing embryos and uncleavenurse eggs or crawling juveniles.The observed material was completely hornogeneous, with only one developmentmode characterized by the presence of nurse eggs. Each egg capsule (n= IS(contains 203-375 eggs (rnean = 303, ~O_ ~_ .54)0 with only. 2 to 12 developirembryos, representing as an average, the 2.4% of the initial egg number. TIaverage uncleaved egg diameter was 214 urn (SO = 13 um, 11=72). Hatchiroccurs at a crawling juvenile stage. Brooding females measured 11-32 mm (me;= 22 mm) in shell length, but in this protandric species the loss of penis can Ialready observed at 11 mm of shell length. Males (with a penis) measured rmmof shell length. This study confirms the presence of C. dilatata in 1Southern Atlantic and, up to our k.nowledge and as far as we observed, res rictsfecunda to the Pacifico [P]