14th International Echinoderm Conference

14th International Echinoderm Conference
Date: 20-24 August 2012
Place: Brussels, Belgium

PRESENTATIONS and ABSTRACTS

1) Baumiller, T. K. 2012. Arm regeneration frequencies in the Florometra serratissima (Crinoidea, Echinodermata): impact of depth of habitat on rates of arm loss.

2) Foltz, D. and Mah, C. 2012. Emergent trends & patterns in modern phylogenetics of the Asteroidea.

Evolution and classification of the Asteroidea (aka the starfishes or sea stars) has included several exchanges that are among the most contentious within echinoderm biology and the field of invertebrate zoology. Discussions in asteroid phylogeny have historically been dominated by discussion of morphological characters from both fossil and living taxa. Only recently have molecular data sets, in conjunction with meaningful and comprehensive taxon sampling, become available to test several of these contentious issues.  Our phylogenetic analysis of the Asteroidea is based on five genes (mitochondrial 12S rDNA, 16S rDNA and COI and nuclear 18S rDNA and early-stage histone H3) totaling about 2Kb of data for 100 ingroup taxa, 14 sea urchin species, 8 brittlestar species and 2 sea cucumber species, and includes nearly every extant family, including the rarely encountered Myxasteridae, the deep-sea Caymanostellidae, and the Xyloplacidae. For some families nearly all genera are included (e.g., Pterasteridae, Odontasteridae).  Efforts at phylogenetic reconstruction are ongoing, but several trends have emerged from independently performed studies using morphological and molecular data sets. General trends are summarized below:
1. Forcipulates+Brisingida are a monophyletic clade that is separated from the other Asteroidea (also Janies et al. 2011, Blake 1987)
2. Velatida are separated from the “Spinulosida”-the Solasteridae and the Echinasteridae. (also Janies et al. 2011, Matsubara et al., 2004)
3. The Solasteridae and Asterinidae are closely related. The Asterinidae may not be monophyletic. (also Janies et al. 2011, Matsubara et al., 2004, Waters et al., 2004)
4. Gale’s “Tripedicellaria” is not supported by any current evidence (also Janies et al. 2011, Blake 1987)
5. We support Paxillosida as derived within the Valvatacea (w/Forcipulataceans as outgroup). (also Janies et al. 2011, Matsubara et al 2005, Blake 1987).
Our analysis also offers further insight into the phylogenetic position of enigmatic members of the asteroid lineage such as Xyloplax and Podosphaeraster. Biogeographic comments related to the Valvatida and the Forcipulatacea are offered in light of our phylogenetic results.

3) Mah, C., Mercier, A., Eleaume, M., Markello, K., Neil, K., Howell, K., Nizinski, M., York, A. and Foltz, D. 2012. Discovery of a globally distributed species of Hippasteria (Goniasteridae; Valvatida) and its implications for classification and taxonomy

The goniasterid starfish Hippasteria includes 15 nominal species and is widely distributed in cold-water settings, usually deep-sea or subpolar (i.e. subArctic or sub Antarctic). Several species of Hippasteria are well-documented predators of cold-water corals and other cnidarians. A single nominal species, Hippasteria phrygiana has been identified as occurring throughout the North and South Atlantic, the South Pacific (New Zealand, Chile) and southern Indian Ocean (Kerguelen). The closely related H. spinosa displays widespread occurrence throughout the North Aleutian Islands and the North Pacific to the Okhotsk Sea. Given the presence of H. phrygiana and H. spinosa in high northern latitudes, it was predicted that these would show trans-Arctic gene flow.  In order to test relationships among the many nominal species of Hippasteria, we sampled populations of Hippasteria spp. throughout the world, including the Aleutian Islands, New Zealand, Chile, North Atlantic (American & European), and Kerguelen Islands in the southern Indian Ocean. Partial sequences for a mitochondrial gene (cytochrome oxidase subunit I) and a nuclear gene (ATP synthase, intron #5) were obtained for approximately 150 specimens.  Our results showed no genetic exchange between trans-Arctic populations. The widespread H. phrygiana identified from Atlantic, New Zealand, and Kerguelen populations and H. spinosa from the North Pacific were all supported as one widely distributed lineage, which has recently diversified. This discovery resolves taxonomic questions regarding widely distributed “species” of Hippasteria that have historically been separated based on minor morphological differences and/or their presence in a specific area. For example, two species, H. hyadesi (from Chile and Patagonia) and H. trojana (New Zealand), are supported as synonyms of H. phrygiana. More surprising is that the widely distributed North Pacific H. spinosa and several closely related species (e.g., H. aleutica) are also apparent synonyms of H. phrygiana.

4) Borrero-Perez G.H. , Honey M. , Bin Kamarudin B.K.R. , Kerr A. , Kim S. , Menez A. , Michonneau F. , Ochoa J.A. , Olavides R.D. , Paulay G. , Samyn Y. , Setyastuti A. , Solis-Marin F. , Starmer J. and VandenSpiegel D. The littoral sea cucumber (Echinodermata: Holothuroidea) fauna of Guam re-assessed – A diversity curve that still does not asymptote.

The Micronesian island of Guam has been an important site for the study of tropical holothuroid taxonomy for almost 200 years. Despite such substantial attention by both expeditions and resident taxonomists, new records are being regularly added to the fauna demonstrating the challenge of documenting the biota of even a small hyper-diverse area. Guam is the type locality of species described by Quoy & Gaimard (1833) and Brandt (1835). A survey of the sea cucumber fauna by Rowe & Doty (1977) led to one of the most used guides for the identification of tropical Pacific sea cucumbers because of the color illustrations of living animals it presented. Focus on echinoderms including holothuroids continued with numerous new records added in the following decades. Paulay (2003) summarized the fauna last, recording 46 species, including 9 new records. At this stage the fauna was thought to be well documented. A week-long workshop on holothuroid systematics sponsered by the NSF PEET project in 2010 included a substantial field work component, sampling both during the day and night, with snorkeling and SCUBA, across a variety of habitats, yielding more than 40 species. 10 of these proved new records for Guam; two proved new to science. Further sampling by Kerr’s lab since the workshop has added two additional species. The holothuroid fauna of Guam thus now comprises 58 species that belong to 17 genera and 7 families. This contribution presents them as an illustrated and briefly annotated checklist.

5) Samyn Y., Michonneau F., Starmer J., Uyeno D., Naruse T., Kerr A., and Paulay G. 2012. The enigmatic sea cucumber Holothuria (Stichothuria) coronopertusa Cherbonnier, 1980 (Echinodermata: Holothuroidea) reexamined.

In 1980, the reknown French taxonomist G. Cherbonnier introduced the new subgenus Stichothuria to accommodate a remarkableNew Caledonian species, Holothuria coronopertusa, characterised by enlarged dorsal and terminal papillae and an ossicle assemblage that combines tables, buttons and C-shaped bodies. Recent surveys in Eastern South Africa, Palau, Guam, and Okinawa obtained additional specimens of H. coronopertusa. In Palau, Guam and Okinawa the species was encountered in deep water (30-100m), while in South Africa it came from relatively shallow depths.  Re-examination of the holotype in the Paris Museumand new material allowed us to redescribe the species and determine its affinities.  We found that the C-shaped ossicles derive from the longitudinal muscles and not from the body wall as thought by Cherbonnier. Such ossicle distribution fits with the diagnosis of the subgenus Mertensiothuria.Phylogenetic analysis based on DNA sequence data clearly place H. coronopertusa among other species of Mertensiothuria.While these results suggest that the species is not that divergent, it remains remarkable because of its large size (to ~1 m), deep habitat in the tropics, and relatively high latitude occurrence.

6) Ausich, W. I., Kammer, T. W., Deline, B., and Sumrall, C. D. 2012. Constructional morphology of the crinoid oral region.

7) Kammer, T. W., Ausich, W. I., Sumrall, C. D. and Deline, B. 2012. Inferring crionid origins based on oral region homologies in pelmatozoans.

Crinoids first appear in Early Ordovician rocks. Their phylogenetic relationships with other echinoderm clades are obscure. Previous approaches that have focused on thecal, arm, and stem characters, typically those best preserved, produce ambiguous results. A new approach focuses on oral region axial skeletal characters (Universal Elemental Homologies) in crinoids and blastozoans, collectively the pelmatozoans. Based on comparative anatomy, the following oral region characters are judged to be generally homologous among early Paleozoic crinoids, glyptocystitid rhombiferans, coronoid blastoids, eumorphocystid diploporans, and eocrinoids: a mouth frame with an identical (or nearly) arrangement of oral plates, moveable peristomial (mouth) and ambulacral cover plates, 2-1-2 ambulacral symmetry, hydropore position, and rigid attachment of the oral surface to the underlying theca. Collectively, these functionally-integrated characters appear to have evolved slowly because of the relative complexity of food processing, thus preserving symplesiomorphic homologies across clades. Derived characters separating these clades include recumbent vs. elevated ambulacra, presence-absence of ambulacral floor plates, brachioles vs. arms, location of the periproct, etc. Phylogenetic hypotheses based on oral region characters suggest crinoids are nested in a larger clade including glyptocystitids and coronoids, with eumorphocystids and eocrinoids as less inclusive sister clades. A previous hypothesis of a close relationship between crinoids and edrioblastid edrioasteroids is not supported based on analysis of oral region characters.