BRISINGIDA, Fisher, 1928

Mah, Christopher & Foltz, David, 2011, Molecular phylogeny of the Forcipulatacea (Asteroidea: Echinodermata): systematics and biogeography, Zoological Journal of the Linnean Society 162 (3), pp. 646-660 : 653

THE BRISINGIDA

Our results ( Figs 2 , 3 ) recover the Freyellidae ( Freyella and Freyastera ) as the sister group to more archetypical brisingidans, such as Hymenodiscus and Astrostephane . The greater taxon sampling in Figure 2 supports the former Freyellidae and Brisingidae as the sister group to Odinella , Brisingaster , and Novodinia . The latter two genera emerge as the sister group to Odinella . This result is similar to the morphology-based phylogenetic trees developed by Mah (1998, 1999), who supported those brisingidans, occurring in shallower depths, with widely abundant papulae present on the abactinal surface ( Odinella , Novodinia , and Brisingaster ), as the sister group to the other, more derived brisingidans.

Mah (1998, 1999) considered Odinella , Novodinia , and Brisingaster as having an intermediate brisingid morphology relative to an asteriid or labidiasterid sister taxon. This was especially the case for Odinella , which has the distinct, wing-like ambulacral ossicles present in asteriids rather than the vertebrae-like ambulacrals present in other brisingidan genera. This perspective is consistent with Mah’s (1998) hypothesis of a bathymetric shift between the shallower-water members of this clade and the deeper-water Freyellidae and Brisingidae .

It should be noted that, although a new classification has not been finalized, our placement of the brisingidans as a derived sister branch to the Asteriidae disagrees with the ordinal-level ranking that places it on a parallel with the Forcipulatida .

Figures

Figure 2. Maximum-likelihood tree for 95 forcipulate taxa and nine velatidan taxa, rooted on 111 taxa belonging to the Valvatida, Paxillosida, and Notomyotida (these taxa have been omitted for clarity), and based on 261 bp of sequence data for the 12S rDNA gene and 437 bp for the 16S rDNA gene. Bootstrap support values are based on 250 pseudoreplicates and are shown as percentages when ± 50%. Named clades correspond either to traditional taxonomic groups or to geographically restricted lineages.

Figure 3. Maximum-likelihood tree for 78 forcipulate taxa and five velatidan taxa, based on 327 bp for the early-stage histone H3 gene plus the same rDNA sequences that were used in Figure 2. Bootstrap support values are based on 200 pseudoreplicates. Other details are as described in Figure 2.