Echinoclathria vasa, Lehnert, Helmut, Stone, Robert & Heimler, Wolfgang, 2006

Lehnert, Helmut, Stone, Robert & Heimler, Wolfgang, 2006, New species of deep­sea demosponges (Porifera) from the Aleutian Islands (Alaska, USA), Zootaxa 1250, pp. 1-35 : 7-10

Echinoclathria vasa sp. nov.

( Fig. 4 a–c, Fig. 5 a–f)

Description

The sponge is stalked, with a vase shaped body ( Figs. 4 a, b, c) growing on exposed bedrock. The stalk is 3 cm high x 0.5–0.8 cm wide, whereas the vase shaped body is 9 x 3 cm, walls 5–10mm in thickness. Consistency, except for the stalk, is very soft and elastic. The color changed from white to orange brown after freezing the sponge.

Skeleton: The ectosome is a thin membrane packed with anchorate isochelae. The choanosome consists of a plumose arrangement of thick, shorter styles. The tracts are 60–135 µm in diameter and often branch in two or three tracts. Near the surface they are replaced by brushes of thin, longer styles, fanning out towards the surface, with many isochelae in between. The brushes of thinner styles overlap considerably and so produce a dense arrangement of spicules near the surface.

Spicules: Megascleres are large thick styles ( Fig. 5 a), measuring 760–920 x 16–21 µm, small thin styles ( Fig. 5 b) with finely acanthose heads ( Fig. 5 c), 740– 1230 x 4–6 µm, being slightly curved to sinuous. Microscleres are reduced, palmate isochelae with narrow central alae which display some variability in structure ( Figs. 5 d, e, f), 21–27 µm.

Discussion

This species is assigned to Echinoclathria because of the occurrence of two categories of styles, the arrangement of the styles in a choanosmal plumose reticulate arrangement of shorter styles followed by subectosomal brushes of longer (thinner) styles and the occurrence of peculiar, reduced isochelae which are regarded as derived from palmate isochelae. Echinoclathria vasa differs from all known species of the genus in the presence of these reduced palmate isochelae. All previously known species possess normal palmate isochelae. There are 33 species of Echinoclathria described, most of them from warm seas. There is only one congener known from the area, E. beringensis ( Hentschel, 1929) . This species lacks microscleres and has two categories of smaller styles (large, 412 µm, small, 176 µm). Echinoclathria foliata ( Bowerbank, 1874) is known from the N­Atlantic. It has a fan­shaped growth form, and further differs in having smaller styles (ectosomal subtylostyles, 196–365 µm, choanosomal styles, 320–570 µm). There is an additional category of acanthostyles (98–280 µm), the isochelae are differently shaped and smaller (16–20 µm) and it has toxas (266–370 µm).

Distribution

Known only from the type­locality.

Etymology

Named after the vase­shaped growth form, from lat. vas­vase.

Figures

FIGURE 4. Echinoclathria vasa sp. nov. a, Holotype. b, Holotype in situ at 744 m depth in Amchitka Pass c, Holotype during collection. Note characteristic shape of upper end of vase.

FIGURE 5. Echinoclathria vasa sp. nov. a, Thick style, lower left to upper right. b, Thin style, lower right to upper left. c, Acanthose end of thin style. d, Palmate isochela, narrow alae, note rounded ends of alae e, palmate isochela, note different points of alae f, Palmate isochela, both alae with two points, upper right acanthose end of thin style.