Une Raie anormale trouv\ue9e \ue0 Concarneau

Volume: 36Start Page: 180End Page: 18

Genome size of some selachian fishes

The nuclear DNA content of 23 chondrich- thyan species (9 Squalomorphii, 11 Batoidea and 3 Galeomorphii) has been studied. Their genome size ranged from 5.4 pg/N in Raja clavata (Batoidea) to 32.3 pg in Ëtmoplerus spinax (Squalomorphii). The lowest values so far recorded for selachians have been reported within the Batoidea, with a slight interspecific variability at the intrafamilial level. In contrast, the Squalomorphii displayed a high DNA content, with values mostly above those of all the other selachians hitherto assayed, and with a wide interspecific variability at the intrafamilial level. The results are discussed in relation to the data for other Chondrichthyes, and comparison is made with the genome size in other vertebrate classes. © 1980 Taylor and Francis Group, LLC

Egg capsules of the yellownose skate Zearaja chilensis (Guichenot 1848) and the roughskin skate Dipturus trachyderma (Krefft and Stehmann 1974) (Rajiformes: Rajidae) from the south-eastern Pacific Ocean

Egg capsules of Zearaja chilensis were obtained from individuals kept in captivity and from dead specimens captured in Valparaíso Bay, central Chile. One female under laboratory conditions deposited three pairs of egg capsules in 6 days. The egg capsules of Dipturus trachyderma were obtained from a female captured in Valdivia, south Chile. Fresh egg capsules of both species were golden-brown and thick walled. Size of egg capsules of Z. chilensis ranged from 94 to 144 mm in capsule length and 64 to 76 mm in capsule width. Those of D. trachyderma ranged between 197 and 199 mm in capsule length and 110. 0 and 129. 0 mm in capsule width. Range and mean values of capsule length and width of egg capsules described in this study were smaller than those reported for the same species in the south-western Atlantic Ocean. This is the first report on egg-laying rate of Z. chilensis and the first description of egg capsules of Z. chilensis and D. trachyderma from the south-eastern Pacific Ocean