GENERIC RESUSCITATION AND REDESCRIPTION OF ACTINOTRYX SANCTITHOMAE DUCHASSAING DE FOMBRESSIN AND...
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Transcript of GENERIC RESUSCITATION AND REDESCRIPTION OF ACTINOTRYX SANCTITHOMAE DUCHASSAING DE FOMBRESSIN AND...
GENERIC RESUSCITATION AND REDESCRIPTION OF ACTINOTRYX SANCTITHOMAE DUCHASSAING DE FOMBRESSIN AND MICHELOTTI, 1860
(CNIDARIA: ANTHOZOA: CORALLIMORPHARIA)
Harim ChaDepartment of Ecology and Evolutionary Biology, Natural History Museum and Biodiversity Research Center
The University of Kansas, Lawrence, KS 66045, USA ([email protected])
• 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
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 sanctithomae and propose resuscitation of the genus Actinotryx in this study.
ABSTRACT
Actinotryx santithomae Duchassaing de Fombressin and Michelotti, 1860
• Illustration in the original description Duchassaing de Fonbressin P. and Michelotti G., 1860, Plate VII , fig. 2
This research is supportedby NSF PEET DEB99-78106 to Dr. Daphne Fautin
Is Actinotryx sanctithomae a species of genus Discosoma?
Family Discosomatidae
Nominal genera
ActinodiscusActinotryxAmplexidiscusDiscosomaMetarhodactisOriniaParadiscosomaPhialactisRhodactis
den Hartog (1980) Classification
Discosoma
Major features distinguishing genera in the family Discosomatidae
• Shape of marginal tentacles
• Shape of distal tentacles
• Tentacle-free zone on oral disc
ACKNOWLEDGMENTS
Dr. Daphne Fautin, Dr. Sandra Romano, Matt Kost
National Science Foundation
KU Natural History Museum & Biodiversity Research Center
University of the Virgin Islands
Comparisons of type species of each genus
Distinctive features ofActinotryx sanctithomae
Type species
Characters
Actinotryx sanctithomae
Oriniatorpida
(SMNH type-71 syntype)
Discosomanummiforme
(SMNH type-1156 syntype)
Rhodactis rhodostoma
Shape of marginal tentacle
Digitiform (length: 3-4 mm in preservative)
Digitiform (length: 2-3 mm in preservative)
Reduced digitiform (length: very short)
Digitiform (length: 4-5 mm in preservative)
Shape of discal tentacles
Papilliform Papilliform Nummiform Branched
Tentacle-free zone on oral disc
Yes Yes No No
Nematocyst composition
Holotrichs up to 250 µm long in mesenterial filaments
Microbasic p-mastigophore
Microbasic b-mastigophore
Type specimen has been severely damaged: impossible to measure nematocysts.
Holotrichs up to 160 µm long in mesenterial filaments
Microbasic p-mastigophore
Microbasic b-mastigophore
Holotrichs up to 180 µm long in mesenterial filaments
Microbasic p-mastigophore
Microbasic b-mastigophore
Sphincter muscle development
Weak - diffuse Weak - diffuse Absent or weak Weak- diffuse
Endosymbionts Yes Yes Yes Yes
Whole specimen
• 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
Conclusion
• Actinotryx is distinguished 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.
1 cm