Obelia racemosa Fraser 1941
Creators
Description
? Obelia racemosa Fraser, 1941b
? Obelia racemosa Fraser, 1941b: 82, pl. 15, fig. 7.
Holotype: USNM 4883: Canada, Nova Scotia, Western Bank, 91–119 m, 0 7 June 1880, schooner Mist, one colony, 25 cm high (Fraser 1941b), in poor condition, gonophores not seen, labelled “ syntype ”; ethanol.
Type locality. Canada, Nova Scotia: Western Bank off Cape Breton Island, 50–65 fm (91–119 m) (Fraser 1941b).
Current status. Species inquirenda.
Remarks. In being designated as the “ type ”, material of Obelia racemosa at the NMNH (USNM 4883) was fixed as the name-bearing type of the species by Fraser (1941b). Although listed as a syntype in the online database, the specimen count is given as “1.” Fraser’s (1941b) original account of the species implies that it was based on a single specimen, as his description began with the words “Colony large….” The type examined here, consisting of one colony and a few fragments of it, is considered the holotype. Obelia racemosa has not been reported again. The holotype specimen is in poor condition, with no hydranths, little or no coenosarc, and few hydrothecae.
Gonosomes were lacking in Fraser’s (1941b) hydroid, and he assigned the species to Obelia Péron & Lesueur, 1810 with question. From his description and illustration, and from the type specimen, however, we consider that generic assignment to be correct.
The principal distinguishing characters of O. racemosa appear to be: (1) the stiff racemes formed by distal branchlets and pedicels, and (2) the densely clustered arrangement of the hydrothecae. Although regarded as a synonym of O. dichotoma (Linnaeus, 1758) in WoRMS, O. racemosa somewhat resembles O. plicata Hincks, 1868 in its strongly polysiphonic colony form. The latter species too, however, is considered identical with O. dichotoma in the current WoRMS list, likely following Cornelius (1990, 1995). Its general mode of branching is similar to O. longissima (Pallas, 1766), but the hydrocaulus of that species is usually monosiphonic. Further study is needed to explore the status of these putative species. Fraser’s hydroid was considered a valid species in Cairns et al. (2002), and listed as O. racemosa.
Notes
Files
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Linked records
Additional details
Identifiers
Biodiversity
- Family
- Campanulariidae
- Genus
- Obelia
- Kingdom
- Animalia
- Order
- Leptothecata
- Phylum
- Cnidaria
- Scientific name authorship
- Fraser
- Species
- racemosa
- Taxon rank
- species
- Type status
- holotype
- Taxonomic concept label
- Obelia racemosa Fraser, 1941 sec. Calder & Choong, 2018
References
- Fraser, C. M. (1941 b) New species of hydroids, mostly from the Αtlantic Ocean, in the United States National Museum. Proceedings of the United States National Museum, 91, 77 - 89. [14 November 1941: noted in Contents page of the journal] https: // doi. org / 10.5479 / si. 00963801.91 - 3125.77
- Peron, F. & Lesueur, C. Α. (1810) Tableau des caracteres generiques et specifiques de toutes les especes de meduses connues jusqu'a ce jour. Annales du Museum d'Histoire Naturelle, 14, 325 - 366.
- Linnaeus, C. (1758) Systema naturae per regna tria naturae, secundum classes, ordines, genera, species cum characteribus, differentiis, synonymis, locis. Editio decima, reformata. Laurentii Salvii, Holmiae, 823 pp.
- Hincks, T. (1868) A history of the British hydroid zoophytes. John van Voorst, London, 338 pp. https: // doi. org / 10.5962 / bhl. title. 1322
- Cornelius, P. F. S. (1990) European Obelia (Cnidaria, Hydroida): systematics and identification. Journal of Natural History, 24, 535 - 578. https: // doi. org / 10.1080 / 00222939000770381
- Cornelius, P. F. S. (1995) North-west European thecate hydroids and their medusae. Part 2. Sertulariidae to Campanulariidae. Synopses of the British Fauna, New Series, 50, 1 - 386.
- Pallas, P. S. (1766) Elenchus zoophytorum sistens generum adumbrationes generaliores et specierum cognitarum succinctas descriptiones cum selectis auctorum synonymis. Franciscum Varrentrapp, Hagae, 451 pp. https: // doi. org / 10.5962 / bhl. title. 6595
- Cairns, S. D., Calder, D. R., Brinckmann-Voss, Α., Castro, C. B., Fautin, D. G., Pugh, P. R., Mills, C. E., Jaap, W. C., Αrai, M. N., Haddock, S. H. D. & Opresko, D. M. (2002) Common and scientific names of aquatic invertebrates from the United States and Canada: Cnidaria and Ctenophora. Second Edition. American Fisheries Society Special Publication, 28, 1 - 115.