PORANIIDAE, Perrier, 1894

Mah, Christopher & Foltz, David, 2011, Molecular phylogeny of the Valvatacea (Asteroidea: Echinodermata), Zoological Journal of the Linnean Society 161 (4), pp. 769-788 : 776

THE PORANIIDAE

The basal phylogenetic position of the Poraniidae relative to the larger cluster of valvataceans is consistent with Blake (1987), who separated the Poraniidae from the Asteropseidae . This is a position contrary to the perspective of traditional revisions, which have often treated the two families as closely linked to one another (e.g. Hotchkiss & Clark, 1976, A.M. Clark, 1984; Gale, 1987a). The thickened dermal tissue present on members from both groups has led to several studies supporting the two groups as closely related (e.g. A.M. Clark, 1984; Gale, 1987b; Blake et al., 2000). Our results are consistent with the notion of Blake et al. (2000), who discussed the possibility that the thickened dermal tissue in the Poraniidae and the Asteropseidae were subject to homeomorphy, which would explain the difficulty in correctly placing these taxa within a classification.

The Poraniidae is represented by two early Mesozoic fossils, the Triassic Noriaster barberoi , described from northern Italy by Blake et al. (2000) and the Middle Jurassic Sphaeriaster jurassicus , described by Hess (1972). Noriaster is supported in Blake et al. (2000) as phylogenetically similar to Porania , suggesting a possible time frame for diversification of the Valvatacea on the tree. The Triassic represents a potentially important period for recognizing diversification in the Asteroidea early in the Mesozoic and the basal location of the Poraniidae does not disagree with Triassic fossil occurrence for the group.