Bryocalyx cinnameus, Cook & Bock, 2000

Cook, P. L. & Bock, P. E., 2000, Two new genera of Bryozoa (Calloporidae) from New Zealand, Journal of Natural History 34 (7), pp. 1125-1133 : 1129-1132

Bryocalyx cinnameus n. sp.

(®gures 3±10)

Material

HOLOTYPE: NZOI, H-611, Station S150, 45 ss46.0¾S, 174ss24.5¾E, east of South Island, 164 m, 26 October 1979, epibenthic sled . PARATYPE, P951, from the same locality, including colonies in ®gures 3, 4; and Museum of Victoria, SEM preparation including zooids in ®gures 5±10, one colony and two fragments .

Etymology

The name cinnameus was suggested by Dr D. P. Gordon, and is derived from the Latin, cinnamum, referring to the cinnamon colour of the colonies.

Distribution South Island, New Zealand.

Description

Colonies conical or fan-shaped, anchored by proximal rhizoids, autozooid frontals facing outwards. Ancestrula elongated, with a proximo-lateral rhizoid; other rhizoids arising during astogeny, as a result of ontogenetic changes to the frontal membranes of proximally placed zooids. Autozooids with shallow lateral walls, raised distally, gymnocyst marginal, smooth. Frontal membrane extensive, operculum terminal, with a marginal sclerite. Zooids communicating through two or three lateral pore-plates, and a row of ®ve or six distal pores within an oval plate with raised rim, which constitutes the entire disto-basal wall. Brooding zooids slightly wider than autozooids, with a wider operculum. Ovicell ectooecium a tripartite skeleton of calci®cation, with large, paired lateral, and a single basal, uncalci®ed foramen, covered by a membrane. Entooecium a thinly calci®ed capsule within the ectooecial structure. The ovicell is tilted backward from the zooid frontal and is bordered proximally by a pair of thick spinous processes; it is not closed by the operculum.

Remarks

The material from Stn S150 comprises more than 230 colonies or parts of colonies. These include 10 complete conical colonies, four with the ancestrula and primary rhizoid present, and 48 fan-shaped colonies with 10 zooids or more present. The remainder consist of smaller fragments of fewer than 10 zooids, some of which, however, have very large frontal rhizoids, and may have had an independent existence. The four largest conical colonies have 50, 25, 24 and 20 zooids, but no ovicells. Each of the larger, isolated, fan-shaped segments has one ovicell, and, on average, 11 autozooids. Two smaller segments of only four autozooids have one and two ovicells present, respectively. The largest colony measures approximately 3.0 mm in height and nearly 2.0 mm in diameter at the upper edge of the cone. The ancestrula is very elongated (La 0.66±0.80 mm), but the primary autozooid budded distally from it is relatively short and stout (Lz 0.50 ±0.60 mm); zooid length increases again with astogeny. The early colony appears to be fan-shaped, although slightly curved towards the basal side. At the second or third generation, one, or an opposing pair of marginal zooids are budded facing basally. These, together with some kenozooidal tissue complete the base of the cone. A rhizoid arises from a proximo-lateral pore and measures 1.0± 1.25 mm in length. Later rhizoids arise from lateral septular pores of autozooids on the basal side of fan-shaped segments. Many secondary rhizoids are very turgid, even when preserved in alcohol, measuring 0.30±0.45 mm in diameter. They may reach 3.0 mm in length and all subdivide terminally, ending in numerous ®ne rootlets, some of which may themselves reach a length of 2.0 mm. Minute foraminiferans and shell fragments, etc., occur in large numbers, adhering to the surface of the rootlets, which form a tangled mass. Some of the secondary rhizoids apparently occur later in astogeny, as an ontogenetic, intussusceptive expansion of the cuticle and epidermis of the frontal membrane of an autozooid (see ®gure 10). In this respect, they resemble the`moribund’ expansions observed by Cook (1985: 37), rather than rhizoids developing from a pore-plate. They function exactly like other rhizoids, but as the zooid from which they originated has an operculum, and, at one time, had an ori®ce, they are not strictly kenozooids.

The large ovicells somewhat resemble those of species of Crassimarginatella at the early stages of their ontogeny, as ®gured by Harmelin (1973). At this point in development, the enveloping ectooecium consists of only a pair of lateral ¯aps, leaving large basal and frontal foramina similar to those of B. cinnameus at the late stages of ovicell ontogeny. The central bar of ovicell calci®cation has a median suture, and the ovicell seems to be formed from two valves, like that of Bryocalyx sp. (see ®gure 8).

Bryocalyx cinnameus resembles Parastichopora vanna Cook and Chimonides (1981) , from south-eastern Australia, which has fan-shaped colonies anchored by rhizoids. However, P. vanna has avicularia and a basal lamina, so that the details of colony structure are not the same. Concertina cultrata Gordon (1986: 27) , from deep water oOE South Island, New Zealand, also has membraniporine zooids and robust rhizoids, but the colonies are bilaminar, and avicularia are present. The mode of life of all these colonies is almost certainly very similar, and resembles that of other sand-fauna species, anchored within, or upon, the surface layers of ®nely particulate sea-bottom sediments.