A Generic Revision of the Stylasteridae (Coelenterata: Hydrozoa) Part 3 Keys to the Genera

摘要: Dichotomous and tabular keys to the 23 genera, 2 subgenera, 5 species groups of Stylasteridae are presented. The stress easily recognized external skeletal characters, most which can be seen using a dissecting microscope, such as: coordination dactylopores gastropores, presence or absence gastroand dactylostyles, cyclosystem orientation, dactylopore spine shape, ampuUar position, gastropore tube length, coenosteal texture. Each these characters is briefly discussed in context its discriminating power phylogenetic value. Two new terms introduced characterize tubes: axial peripheral. Numbers valid for each genus their geographic bathymetric ranges listed. hundred twenty-four stylasterid considered valid, including 24 exclusively fossil species. Stylasterids cosmopolitan, but insular, distribution, ranging from 0-2,789 m. This third an originally conceived two part series, first being description genera (Cairns, 1983b), second analysis those 1984). However, faced with need identify large collection stylasterids following 2-year hiatus study, I found it useful construct herein publish both dichotomous family. Such key could have been extracted coded data matrix published 1984: 52-53, appendix 2); however, were not presented fashion that allowed easy interpretation ready use as key. aim provide efficient accurate method compare characters. used therefore necessarily important phylogenetically 1984; 1987), group distinguish based on obvious, artificial keys, reflect organization many divisions suggested by Cairns (1984; 1987). order roughly phylogenetic, descending degree derivation. DISCUSSION OF CHARACTERS USED IN THE TABULAR KEY was determined ability discriminate taxa ease recognition: more conservative listed left right. Characters 15 10 all characters; 6-8 require observations cross longitudinal section branch; character 9 best viewed aid scanning electron microscopy. will discussed; illustrations definitions structures (1983a; 1983b; 1986a; 1986b; Table 1). increase gastropores major evolutionary trend within 1987): lack least derived state arrangement derived.