dcsimg

Description

provided by NMNH Antarctic Invertebrates

"Adelascopora gen. nov.

Diagnosis

Colony erect, bilaminate, branching, with or without chitinous nodes. Autozooids with cryptocystidean frontal calcification, perforated by numerous small pseudo-pores ; a simple, crescentic ascopore present in the middle of the frontal surface. Vertical walls with large, multiporous septula. Primary orifice more or less semicircular ; the proximal border straight, with an indistinct condylar ridge. ovicells globular, prominent, budded from the proximal frontal wall of the autozooid distally succeeding the maternal autozooid ; entooecium thinly calcified, ectooecium entirely membranous ; aperture small, overhanging orifice of maternal autozooid. No avicularia. No spines.

Type species : Microporella divaricata Canu, 1904.

Discussion

M. divaricata Canu (Fig. 5A-D) differs from all other species of Microporella in its unusual colony form. It also differs in its interzooidal communication system, which in Microporella consists of well-calcified basal pore chambers, in its lack of avicularia, and, most importantly, in its ovicell. In all species of Microporella the ovicell is recumbent, thickly calcified, and is closed by the operculum of the brooding autozooid. In species of Fenestrulina the calcification of the ectooecium is generally thin, and may be incomplete, but in all species of that genus the auto-zooids are linked by substantial basal pore chambers, and have also a complexly calcified ascopore. Microporella divaricata is thus seen to be sufficiently distinct from other species of the Microporellidae to warrant a separate generic identity, and is here designated as type species of the new genus Adelascopora. A second species has also been isolated from the "Discovery" samples and is described below as Adelascopora secunda sp. nov.

Geographical distribution

Adelascopora divaricata was reported from the Bellingshausen Sea by Waters (1904), who recognized it as the same species described by Canu (1904) from Tertiary deposits of Patagonia. Part of Canu's material is conserved in the Waters Collection at the Manchester Museum. It is, as far as it is possible to judge, closely similar to the present specimens, but differs in that the autozooids are much smaller. It is possible that the Recent material represents a different species, but more fossil specimens are required before this possibility can be considered. Subsequent reports of Recent A. divaricata, are those of Livingstone (1928) from Queen Mary Land, and Androsova (1972) from Adelie Land. The present material comprises four samples, from the Palmer Archipelago ("Discovery" stn. 160), Oates Land ("Terra Nova" stn. 194), and the Ross Sea ("Terra Nova" stn. 316, "Discovery" stn. 1660)." (Hayward & Thorpe, 1988: 292)