Celleporella marionensis, Branch & Hayward, 2005

Branch, M. L. & Hayward, P. J., 2005, New species of cheilostomatous Bryozoa from subantarctic Marion and Prince Edward Islands, Journal of Natural History 39 (29), pp. 2671-2704 : 2687-2689

Family HIPPOTHOIDAE Busk, 1859

Genus Celleporella Gray, 1848 Celleporella marionensis sp. nov.

( Figure 8 A–E)

Material

Holotype: St. 55 Marion Island (46 ° 55 9 S, 37 ° 35 9 E), 42–47 m, SAM A27555 . Paratype: St. 20 Marion Island (46 ° 49 9 S, 37 ° 41 9 E), 34–42 m, SAM A27473 .

Other material. St. 31 Marion Island (46 ° 60 9 S, 37 ° 55 9 E), 42–85 m, SAM A27474 .

Description

Colony forming thick, fan-shaped sheets, encrusting pebbles, coherent but with small spaces between the tubular communication structures linking adjacent zooids. Autozooids, ovicelled female zooids and presumed male zooids present. Autozooids elongate oval, convex; commonly 0.4–0.45X, 0.2 mm; primary orifice as long as wide, 0.09 mm; with a deep U-shaped sinus comprising approximately one-fifth total length and occupying half the total proximal width; condyles distinct, bifid; frontal shield with coarse, transverse corrugations and three to four prominent umbones in a longitudinal series down the midline. Female zooid slightly shorter than autozooid; primary orifice wider than long, more or less D-shaped, proximal edge almost straight, with a short, narrow, U-shaped sinus; frontal shield with three to four prominent umbones in a median longitudinal series, the distalmost umbo not completely obscuring the orifice; ovicell globular with about six large pores around its periphery, and up to nine blunt umbones on its frontal surface. Male zooids smaller than autozoids, up to 0.3 mm long, with smaller orifice, 0.04 mm wide. Ancestrula not present.

Etymology

Named with reference to the type locality.

Remarks

This species is most similar to C. bougainυillei (d’Orbigny, 1842), which is common in shallow coastal waters of magellanic South America and ranges southwards to South Georgia and the tip of the Antarctic Peninsula. It differs in the proportionately larger sinus of the autozooid orifice, and in the morphology of the female zooid, in which the sinus is proportionately much smaller than in the latter species, and distinctly parallel-sided rather than rounded. The ovicell of C. marionensis is similar to that seen in some populations of C. bougainυillei in having peripheral perforations ( Moyano 1986), but differs in bearing a conspicuous group of frontal umbones. Significantly, all specimens of C. marionensis sp. nov. encrusted pebbles from depths of 35–84 m, while C. bougainυillei seems to be invariably associated with algae.

Celleporella bougainυillei is also recorded here from Marion Island, considerably extending its known geographical range. However, in view of the facts that the type locality of C. bougainυillei is the Falkland Isles; that d’Orbigny’s original materials do not seem to have been described or figured again since the introduction of the taxon, and that Moyano (1986) has drawn attention to morphological differences between geographically remote populations of the species, it may prove to be that this extensive range encompasses several similar but distinct species.

Celleporella alia Hayward, 1993 , previously known only from the South Orkney Islands, South Georgia and the southern Patagonian Shelf, is also here recorded from Marion Island. It forms thin, translucent sheets on bryozoans and on hydrozoans such as Lafoea dumosa and Symplectoscyphus subdichotomous The autozooids of C. alia are closely conjoined and rather flat; the frontal shield bears fine longitudinal ridges and transverse wrinkles but umbones are small and sparsely developed. The female zooid has an ovicell with about 20 tubaeform pores, and its orifice has a V-shaped sinus.

Figures

Figure 8. Celleporella marionensis sp. nov., SAM A27555: (A) female zooid with ovicell, small male zooid and orifice of autozooid, X150; (B) autozooid with two distal spines, X200; (C) orifice of autozooid, X450; (D) female orifice, X450; (E) male orifice, X450.