Synthecium nanum Fraser, 1943a

Sertularia tubitheca Αllman, 1877: 24, pl. 16, figs. 5, 6.

Synthecium tubithecum .— Jäderholm, 1903: 291, pl. 13, fig. 7.

Synthecium nanum Fraser, 1943a: 80, pl. 18, fig. 10.

Holotype. MCZ-IZ 9003: USA, Florida, W of the Dry Tortugas, 24°36’40”N, 83°02’20”W, 22 January 1868, 16 fm (29 m), Pourtalès Gulf Stream Exploration, Steamer Bibb, one colony, 3 mm high, with three hydrothecal pairs, in only fair condition, on stem of Thyroscyphus marginatus (Allman, 1877), without gonophores, coll. L.F. de Pourtalès, labelled “ type ”; ethanol.

Type locality. USA, Florida: off Dry Tortugas, 24°36’40”N, 83°02’20”W, 16 fm (29 m), Pourtalès Gulf Stream Exploration (Fraser 1943a).

Current status. Invalid.

Remarks. Fraser (1943a) described Synthecium nanum from a collection of hydroids at the MCZ. No types of it were designated therein by him, but the species is based on known material (MCZ-IZ 9003). Little data are included with this hydroid in the current online database of the MCZ, and the number of specimens is unstated. However, in a very brief account, Fraser (1943a) described the hydroid as “…consisting of a single, unbranched, erect stem…” No other type material of the species is known to exist. The type, examined during this study, is indeed a single small colony. It is therefore the holotype by monotypy.

Synthecium nanum is, as noted earlier (Calder 1991), a junior subjective synonym of S. tubithecum (Allman, 1877) . Fraser’s (1943a) hydroid was originally found in the same sample as Allman’s (1877) type of S. tubithecum . The specimen is considered a juvenile colony of that well-known species.