Gonothyraea integra Fraser, 1940a

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: 69

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Gonothyraea integra Fraser, 1940a


Gonothyraea integra Fraser, 1940a 

Lomedea gracilis Dana, 1846: 689  , pl. 61, figs. 7a, b [incorrect subsequent spelling of the generic name Laomedea  ] [binomen suppressed by the ICZN for the purposes of both the Principle of Priority and the Principle of Homonymy (Opinion 1465)].

Obelia hyalina Clarke, 1879: 241  , pl. 4, fig. 21.

Obelia congdoni Hargitt, 1909: 375  .

Laomedea sargassi Broch, 1913: 13  .

Gonothyraea integra Fraser, 1940a: 576  , pl. 32, fig. 3.

Holotype. USNM 43435View Materials: USA, Rhode Island, Block Island, near North Light , 24 August 1880, R/ V Fish Hawk, 24 m, one colony, now on four fragments of a species of Sargassum  and with some hydroid fragments detached, 8 mm high, in fair to fairly poor condition, with gonophores, labelled “ type ”; other species of hydroids present; ethanol. 

Paratypes. BCPM 976-00403-001: USA, Rhode Island, Block Island, near North Light, 24 August 1880, 24 m, on Sargassum  , in poor condition, with gonothecae, labelled “cotype”; dry at some time, 60% IPA.

BCPM 976-00403-002: USA, Rhode Island, Block Island, North Light , 24 August 1880, on Sargassum  , one colony, 1.2 cm high, in relatively poor condition, with gonothecae; slide (slide cover slip broken). 

Type locality. USA, Rhode Island: Block Island, 1¼ miles (2 km) from North Light, 13 fathoms (24 m), on sunken Sargassum ( Fraser 1940a)  .

Current status. Invalid.

Remarks. Fraser (1940a) designated material at the NMNH ( USNM 43435) as the “ type ” (i.e., the namebearing type) of Gonothyraea integra  . It is listed as the holotype in the online database of the NMNH. While its substrate (a species of Sargassum  ) is now in four fragments, the hydroids on them are likely all part of the same colony and indeed comprise the holotype. Specimens in the Fraser Hydroid Collection at the RBCM ( BCPM 976- 00403-001; BCPM 976-00403-002) are paratypes.

Hydroids described as Gonothyraea integra  by Fraser (1940a) were collected on sunken Sargassum  at a depth of 13 fm (24 m) off Block Island, Rhode Island, USA. From his generic assignment of the species, Fraser must have assumed that its gonophores were vestigial medusoids but, from examination of the holotype, we believe they are developing medusae. It is probable that this species is the common obeliid of the pelagic Sargassum  community in the North Atlantic Ocean. That hydroid, commonly assigned over the last few decades of the 20th century to Obelia dichotoma ( Linnaeus, 1758)  , is now considered a different species. The earliest name applied to it was Lomedea gracilis Dana, 1846  (= Laomedea gracilis  ), based on specimens from “Gulf-weed” in the Gulf Stream off North Carolina. That specific name, however, has been placed on the Official Index of Rejected and Invalid Specific Names in Zoology (ICZN Opinion 1465). Obelia hyalina Clarke, 1879  , the next available name, was resurrected for the species in a previous work ( Calder 2013). Junior synonyms of O. hyalina  , recognized as the valid name of the species here, include O. congdoni Hargitt, 1909  and Laomedea sargassi Broch, 1913  . Names applied by Bosc (1797) to hydroids on pelagic Sargassum  , including one vaguely resembling O. hyalina  , have not been used as valid for more than a century. Most are nomena dubia, and in the interests of nomenclatural stability are best abandoned.


British Columbia Provincial Museum


Empresa Pernambucana de Pesquisa Agropecu�ria, IPA


Smithsonian Institution, National Museum of Natural History


Smithsonian Institution, National Museum of Natural History


Royal British Columbia Museum














Gonothyraea integra Fraser, 1940a

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

Lomedea gracilis

Dana, 1846 : 689

Obelia hyalina

Clarke, 1879 : 241

Obelia congdoni

Hargitt, 1909 : 375

Laomedea sargassi

Broch, 1913 : 13

Gonothyraea integra

Fraser, 1940a : 576