GENERIC RESUSCITATION AND REDESCRIPTION OF

1. This research is supportedby NSF PEET DEB99-78106 to Dr. Daphne Fautin 1 cm GENERIC RESUSCITATION AND REDESCRIPTION OF ACTINOTRYX SANCTITHOMAE DUCHASSAING DE FOMBRESSIN AND MICHELOTTI, 1860 (CNIDARIA: ANTHOZOA: CORALLIMORPHARIA) Harim Cha Department of Ecology and Evolutionary Biology, Natural History Museum and Biodiversity Research Center The University of Kansas, Lawrence, KS 66045, USA (harim@ku.edu) ABSTRACT Actinotryx sanctithomae Duchassaing de Fombressin and Michelotti, 1860 is the only species of genus Actinotryx, which belongs to family Discosomatidae. The Actinotryx has been confused with and is in partial synonymy with most genera in the family Discosomatidae; it is important to clearly circumscribe Actinotryx to resolve nomenclatural ambiguity at the genus level. Type specimens of A. sanctithomae are not extant and specimens of the type were collected from type locality, St. Thomas, US Virgin Islands in August 2004. The specimens were examined and identified as A. sanctithomae based on the original description containing an illustration including several critical morphological features for recognition of A. sanctithomae. The morphological characters are distinct from the ones of other type species of genera in the family Discosomatidae. I redescribe Actinotryx sanctithomaeand propose resuscitation of the genus Actinotryxin this study. Distinctive features of Actinotryx sanctithomae Actinotryx santithomae Duchassaing de Fombressin and Michelotti, 1860 Major features distinguishing genera in the family Discosomatidae • Type species of genus Actinotryx • Type specimens: no longer exist • Type locality:St. Thomas, US Virgin Islands • Where does this species belong? Genus ActinotryxGenus OriniaGenus DiscosomaGenus Rhodactis • Shape of marginal tentacles • Shape of distal tentacles • Tentacle-free zone on oral disc • Nematocyst composition • Endosymbionts • Digitiform marginal tentacles • Papilliform discal tentacles • Tentacle-free zone between marginal and discal tentacles • No distinct sphincter muscle • Holotrichs in mesenterial filaments up to 250 um long • Weak mesogleal development Comparisons of type species of each genus • Illustration in the original description • Duchassaing de Fonbressin P. and Michelotti G., 1860, Plate VII , fig. 2 Conclusion • Actinotryx isdistinguished from Discosoma with which it has been synonymized: its two most distinctive characters are a tentacle-free zone on the oral disc and size of holotrichs in the mesenterial filaments. • Actinotryx sanctithomae is the type species of genus Actinotryx: neotype designation is required. • Orinia torpida, type species of genus Orinia, is a junior synonym of Actinotryx sanctithomae. Family Discosomatidae den Hartog (1980) Classification Discosoma Nominal genera Actinodiscus Actinotryx Amplexidiscus Discosoma Metarhodactis Orinia Paradiscosoma Phialactis Rhodactis ACKNOWLEDGMENTS  Dr. Daphne Fautin, Dr. Sandra Romano, Matt Kost  National Science Foundation  KU Natural History Museum & Biodiversity Research Center  University of the Virgin Islands Is Actinotryx sanctithomae a species of genus Discosoma?