Staurotheca profunda, Pena Cantero & Vervoort, 2003

Cantero, A. L. Peña & Vervoort, W., 2003, Species of Staurotheca Allman, 1888 (Cnidaria: Hydrozoa: Sertulariidae) from US Antarctic expeditions, with the description of three new species, Journal of Natural History 37 (22), pp. 2653-2722 : 2703-2705

Staurotheca profunda sp. nov.

(figure 16; table 5)

Material examined. 22 / 1592, one fragment ca 30 mm long (holotype, USNM 1003273 ) .

Description. Material consisting of a single fragment ca 30 mm long, polysiphonic over almost its entire length. Main stem giving rise to three branches on the same side and another branch on the opposite side; branching approximately in one plane.

Hydrothecae alternately arranged in one plane (figure 16A, B), forming two longitudinal rows. Hydrothecae (figure 16A–C) only slightly immersed into the branches, strongly curved outwards. Adcauline hydrothecal wall free for approximately half of its length. Free adcauline wall straight or slightly convex. Abcauline hydrothecal wall concave. Aperture circular; rim even and usually provided with numerous short renovations, tilted downwards, forming an acute angle with long axis of branch. Hydrotheca lacking mushroom-shaped diaphragm.

Gonothecae not found.

Remarks. In spite of the scarcity of available material, there is enough evidence to conclude that we are dealing with a new species. Staurotheca profunda sp. nov. is characterized by the arrangement of the hydrothecae, in alternate pairs (cf. table 6), and by the shape of the hydrothecae that have a dish-shaped operculum, strongly pointing towards the inclusion of this species in the genus Staurotheca .

The alternate arrangement of the hydrothecae in two longitudinal rows is unusual in the genus (cf. table 6). Only S. abyssalis sp. nov. has the same disposition as a general feature, although S. australis , S. stolonifera and S. vervoorti also have hydrothecae arranged in two longitudinal rows, usually in (sub)opposite pairs (in S. australis and S. stolonifera also in an alternate pattern). Staurotheca amphorophora may occasionally have two longitudinal rows of hydrothecae arranged in (sub)opposite pairs.

Staurotheca profunda sp. nov. differs from all those species by the shape of the hydrotheca. In Staurotheca abyssalis sp. nov. the hydrotheca is adnate to the branch for ca one-quarter of its adcauline length. In S. vervoorti , by contrast, the hydrotheca is adnate for its full adcauline length. In S. stolonifera , the hydrotheca is free for ca one-third to one-quarter of its adcauline length. Finally, in S. australis the hydrotheca is different and it is adnate to the branch for a much longer part of the adcauline wall.

Ecology and distribution. Staurotheca profunda sp. nov. has been collected from depths between 1647 and 2044 m at Burdwood Bank (Scotia Sea).

Etymology. The specific name profunda refers to the deep waters from which it originates.

Hydrothecae

Length of abcauline wall 900–950 Length of free adcauline wall 530–650 Length of adnate adcauline wall 650–740 Length of adcauline wall 1180–1310 Diameter at rim 320–370