Plumularia polynema Fraser, 1941b

Plumularia polynema Fraser, 1941b: 87, pl. 18, figs. 15a, b.

Holotype. USNM 43459: USA, Massachusetts, off Martha’s Vineyard, R / V Fish Hawk Sta. 1092, 39°58’N, 69°42’W, 369 m, 11 August 1882, trawl, several fragments of a colony, the largest ones 7 mm, 5 mm, and 5 mm long, in rather poor condition, without gonophores, labelled “ type ”; ethanol.

Paratypes. USNM 24360: USA, Massachusetts, off Martha’s Vineyard; ethanol.

BCPM 976-00928-001: USA, Massachusetts, off Martha’s Vineyard, “near USFC Stn. 1038”, in poor condition, without gonothecae; 60% IPA.

Type locality. USA, Massachusetts: off Martha’s Vineyard, 39°58’N, 69°42’W, 202 fm (369 m) (Fraser 1941b).

Current status. Valid.

Remarks. In describing Plumularia polynema, Fraser (1941b) designated material at the NMNH (USNM 43459) as its “ type ”. That collection, thereby fixed as the name-bearing type of the species, is currently listed as syntype material in the NMNH online database. Regarded here as the holotype, the specimen is in three main fragments, two of them corresponding with original illustrations of the species (Fraser 1941b, pl. 18, figs. 15a, b). Fraser’s description mentions a fragment of the hydroid reaching 83 mm in length, but nothing approaching that size exists in the holotype collection.

Another collection of Plumularia polynema mentioned in Fraser’s account (USA, Massachusetts, off Martha’s Vineyard, R/V Fish Hawk Sta. 1038, 39°58’N, 70°06’W; 238 m, 21 September 1881; thought to be material in USNM 24360) was not nominated by him as a type and is excluded from the type series (ICZN Art. 72.4.6). So too is a collection of the species from off Martha’s Vineyard in the Fraser Hydroid Collection at the RBCM (BCPM 976-00928-001). Both of these collections are listed instead as paratypes (ICZN Art. 72.1.3).

This little-known hydroid, from the upper continental slope off Martha’s Vineyard, is currently considered a species inquirenda in WoRMS. Although poorly characterized, we prefer to recognize it as valid based on its bathyal type locality. The gonosome of the species remains unknown.