Obelia racemosa Fraser, 1941b

Calder, Dale R. & Choong, Henry H. C., 2018, Names of hydroids (Cnidaria, Hydrozoa) established by Charles McLean Fraser (1872 - 1946), excluding those from Allan Hancock Expeditions, Zootaxa 4487 (1), pp. 1-83: 71

publication ID

https://doi.org/10.11646/zootaxa.4487.1.1

publication LSID

lsid:zoobank.org:pub:524B23B9-8EAA-4BD6-8937-A1B8F1C057B9

persistent identifier

http://treatment.plazi.org/id/0392282A-FFA0-FFA2-AEC1-5FA0188FFBDB

treatment provided by

Plazi

scientific name

Obelia racemosa Fraser, 1941b
status

 

? Obelia racemosa Fraser, 1941b 

? Obelia racemosa Fraser, 1941b: 82  , pl. 15, fig. 7.

Holotype: USNMAbout 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 NMNHAbout NMNH ( USNMAbout 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  .

USNM

Smithsonian Institution, National Museum of Natural History

NMNH

Smithsonian Institution, National Museum of Natural History

Kingdom

Animalia

Phylum

Cnidaria

Class

Hydrozoa

Order

Leptothecata

Family

Campanulariidae

Genus

Obelia

Loc

Obelia racemosa Fraser, 1941b

Calder, Dale R. & Choong, Henry H. C. 2018

2018
Loc

Obelia racemosa

: 82