Hart, M. W., Jeffrey, C. H. & Emlet, R. B. 2011. Molecular phylogeny of echinometrid sea urchins: more species of Heliocidaris with derived modes of reproduction. Invertebrate Biology 130, 175-185.

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Publication

Pachechinus bajulus is an endemic Australian sea urchin with an unusual mode of brooded larval development. We used mitochondrial and nuclear gene sequences to estimate the phylogenetic relationships among Pachechinus and other Echinometridae, including wellstudied species of Heliocidaris with planktonic development. We found strong evidence for the planktotrophic species Heliocidaris tuberculata as the sister group to a clade of three closely related species in which development is known (Heliocidaris erythrogramma, P. bajulus) or suspected (Pachechinus australiae) to be lecithotrophic. Clade support values and likelihood ratio tests rejected monophyly of Heliocidaris species. The sister group to H. erythrogramma is most likely the two Pachechinus species. We resolve the paraphyly problem by reassigning the Pachechinus species to the genus Heliocidaris (the senior synonym), which has six extant species including Heliocidaris australiae and Heliocidaris bajulus. The phylogeny has potentially important implications for comparative studies of developmental morphology and genetics that have assumed a close sister-group relationship between H. erythrogramma and H. tuberculata, and highlights the need for such data from H. bajulus and other Heliocidaris species.

Echinoidea

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