STICHASTERIDAE AND

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 : 652

THE STICHASTERIDAE AND SYNONYMY OF THE NEOMORPHASTERIDAE

Among the most diverse stemward clades is a lineage (99% bootstrap support on the two-gene tree; 100% bootstrap support on the 3-gene tree) that includes nearly all members of the Stichasteridae , as designated by Perrier (1885) and Sladen (1889). Perrier’s (1885) Stichasteridae included Stichaster , Neomorphaster , and Granaster . Sladen (1889) modified the Stichasteridae to include Stichaster , Neomorphaster , and Tarsaster , as well as Stichaster (= Allostichaster ) polyplax and Stichaster (= Cosmasterias ) felipes. Our results also show Neosmilaster , Pseudechinaster , and Smilasterias as members of the Stichasteridae .

Our results uphold Stichaster as monophyletic, but not Cosmasterias . Cosmasterias dyscrita was separated from a larger clade of Stichasteridae in both trees. In the three-gene tree, Cosmasterias lurida is a member of the sister group to the large clade containing C. dyscrita . In the two-gene tree, C. lurida is supported as part of the same clade as C. dyscrita .

Based on the position of Neomorphaster within the stichasterid clade, the monotypic Neomorphasteridae Fisher, 1923 should be synonymized with the Stichasteridae Perrier, 1885 . Our results do not support Neomorphaster as the sister taxon to Zoroaster , as indicated by Mah (2000). However, the shared morphological similarities may be indicative of plesiomorphic character states between zoroasterids and stichasterids.

Sampled members of the Stichasteridae lineage are limited to temperate waters in the Southern Hemisphere, with two exceptions: the deep-water Neomorphaster occurring in the Northern Hemisphere in the North Atlantic (none have been reported from the South Atlantic), and Neosmilaster sp. nov. (supported as the sister to Neosmilaster steineni ) from the North Pacific. The unsampled North Atlantic Stichasterella was placed within the Stichasteridae by Mortensen (1927), based on several shared morphological characters. If Stichasterella is upheld as a member of this clade, it would also be included among the Northern Hemisphere Stichasteridae . There is evidence that the stichasterid lineage has experienced some extinction and range restriction. Blake & Peterson (1993) described the Neomorphaster -like Pegaster from the Cretaceous of California. A significant level of forcipulatacean diversity that is restricted to the Australia / New Zealand /South Pacific region includes members of the stichasterid clade, including Stichaster , Pseudechinaster , Allostichaster , Smilasterias , and ‘ Cosmasterias ’ dyscrita (a separate lineage from C. lurida ). Only the shallow-water South Australian Uniophora was absent from our sampling. However, Uniophora shares several morphological characters with other stichasterids, and therefore we suggest it will probably be included as a member of the Stichasteridae in future molecular phylogenetic studies.