Comparative neurocranial morphology of angelsharks from the south-western Atlantic Ocean (Chondrichthyes, Elasmobranchii, Squatinidae): implications for taxonomy and phylogeny

Neurocrania of three species of angelsharks from the south-western Atlantic Ocean, occurring off south-eastern and southern Brazil, are described. A detailed morphological description is provided of the neurocranium of Squatina guggenheim and compared with S. argentina and S. occulta. Despite being generally conservative, the neurocranium of Squatina presents significant differences among these species which aid in their identification, which is otherwise problematical. The main distinctions were found in rostral projections, anterior fontanellae, supraorbital crests, upper and lower postorbital processes, otic capsules, suborbital crests, and pterotic processes. Squatina guggenheim and S. occulta share more neurocranial characters when compared to S. argentina. No basal angle was found, but we confirm the presence of a very much reduced and barely noticeable basioccipital fovea in Squatina; systematic implications within elasmobranchs of these and other features are discussed.

Ahamulina n. gen. (Cestoda: Diphyllidea) from the polkadot catshark, Scyliorhinus besnardi (Carcharhiniformes: Scyliorhinidae), off Brazil

A new genus and species of diphyllidean, Ahamulina catarina n. gen. n. sp., is described from the polkadot catshark, Scyliorhinus besnardi, from Santa Catarina, Brazil. The new genus exhibits apical organ armature that is unique among diphyllideans in the arrangement and shape of the apical hooks as well as in the lack of lateral hooklets. The taxon also exhibits a bipartite cirrus sac. This is the seventh diphyllidean reported from a shark, and the third reported from a catshark suggesting that the dearth of cestode data for these particular sharks belies the true extent of diphyllidean diversity they host.