CRIBRILINIDAE Hincks, 1879

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 : 2682-2684

Family CRIBRILINIDAE Hincks, 1879

Genus Filaguria Moyano, 1991 Filaguria lithocrustata sp. nov.

( Figure 6A, B )

Material

Holotype: St. 53 Marion Island (46 ° 55 9 S, 37 ° 33 9 E), 600–775 m, SAM A27523 . Paratype: St. 17 Marion Island (46 ° 41 9 S, 37 ° 49 9 E), 335–375 m, SAM A27524 .

Other material. St. 16 Marion Island (46 ° 51 9 S, 38 ° 04 9 E), 160–170 m, SAM A27522 .

Description

Colonies forming small irregular patches on rock, thickly calcified. Autozooids oval, convex, separated by deep grooves; 0.8–1.1X 0.55–0.6 mm. Gymnocyst reduced forming a smooth, imperforate rim around autozooid. Frontal shield consisting of 14–21 (most commonly 18–20) broad costae, not touching around the edges of the shield but fused medially, and at two to three points along their length, leaving large round lacunae between them. One small uncalcified spot (pelmatidium) present on the surface of most costae, usually at the second point of fusion between adjacent costae. The distalmost pair of costae with broad bases, and especially thickened, forming a stout, nodular apertural bar. Aperture bordered by four to six (usually five) short, stout, flattened and basally jointed oral spines; proximal pair persist in ovicelled zooids. Large avicularia absent. Ovicell elongate oval, about 0.3 mm longX 0.4 mm wide; hyperstomial, with a longitudinal median ridge and, on each side, an elongate, drop-shaped, transverse frontal fenestra; closed by autozooidal operculum. Small, irregularly shaped kenozooids sporadically distributed throughout the colony, lacking an aperture and with a complete, though reduced, frontal shield.

Etymology

Greek, lithos, stone; Latin, crusta, shell or rind, with reference to the growth habit of the species.

Remarks

Filaguria lithocrustata sp. nov. is very similar to the Antarctic species Filaguria spatulata (Calvet, 1909) , which also has about 20 costae, fused medially and at one or two points along their length, and four to five oral spines. However, in F. spatulata the uncalcified spots on the surfaces of the costae are situated close to the median line of fusion of the costae ( Moyano 1991, Plates 8, 9), while in F. lithocrustata sp. nov. they are not median in position, but usually close to the second point of lateral fusion between adjacent costae. Filaguria lithocrustata differs from F. spatulata in its larger autozooids, and in the prominent, thickened apertural bar, which does not occur in the latter species. The ovicell of F. lithocrustata sp. nov. has a distinctive shape, with narrow drop-shaped fenestrae, and large avicularia are absent.

D’Hondt (1979) listed F. spatulata from Heard Island and McDonald Island, in the southern Indian Ocean, although it is otherwise known no further north than the South Shetland Isles. The source of d’Hondt’s records is not apparent.

Figures

Figure 6. (A, B) Filaguria lithocrustata sp. nov., SAM A27523: (A) ovicelled autozooid, X70; (B) autozooids and a small kenozooid, X40. (C–E) Sclerodomus myriozoides, SAM A27530: (C) part of colony plus young branch, X15; (D) abfrontal view of colony showing four series of autozoids, X30; (E) aperture showing associated avicularia.