Celleporaria pilaefera ( Canu and Bassler, 1929 )

Dick, Matthew H. & Grischenko, Andrei V., 2016, Rocky-intertidal cheilostome bryozoans from the vicinity of the Sesoko Biological Station, west-central Okinawa, Japan, Journal of Natural History 51 (3 - 4), pp. 141-266 : 186-187

Celleporaria pilaefera ( Canu and Bassler, 1929)

( Figure 14 (a–e))

Holoporella pilaefera Canu and Bassler 1929, p. 422 , pl. 60, figs 2–6.

Celleporaria pilaefera: Hayward 1988, p. 343 , pl. 16e, f. Tilbrook et al. 2001, p. 70, fig. 13 (a–c). Tilbrook 2006, p. 135, pl. 24A, B.

Not Celleporaria pilaefera: Scholz 1991, p. 300 , pl. 10, fig. 4.

Material examined

NSMT-Te 1092 ( SES- 21), bleached, on SEM stub; NSMT-Te 1093 (REEF-5), bleached, on SEM stub; NSMT-Te 1094, dried colony, SES site; NSMT-Te 1095, dried colony, SES site; NSMT-Te 1096, two dried fragments, REEF site; NHMUK 2016.5.13.22 ( SES- 22), bleached, on SEM stub; NHMUK 2016.5.13.23-25, three dried fragments, SES site.

Measurements

AzL, 0.37–0.59 (0.461 ± 0.057); AzW, 0.23–0.39 (0.322 ± 0.035) (n = 45, 3). OrL, 0.09–0.15 (0.121 ± 0.012); OrW, 0.12–0.19 (0.152 ± 0.012) (n = 45, 3). OvL × OvW, 0.26 × 0.32, 0.19 × 0.29 (n = 2). Largest colony observed 12 mm across.

Description

Colony forming an encrusting sheet, initially unilaminar but becoming multilaminar and disclike due to frontal budding; whitish to light tan; operculum light brownish-yellow. Zooids at colony margin ( Figure 14 (a)) irregularly hexagonal, barrel-shaped or nearly quadrate; delineated by incision and shallow groove. Frontal wall convex, uniformly finely granulated, with eight to 13 small, round areolae around margin; areolae sometimes offset from margin. Primary orifice ( Figure 14 (b)) D-shaped, with shallowly concave proximal margin; slightly broader than long. Condyles small, rounded; close to corners of orifice, pointing proximomedially. Oral spines lacking. Early in ontogeny, uniporous septulum in frontal wall gives rise to suboral avicularian chamber proximal to orifice, offset to one side or other; chamber bears conical umbonate process ( Figure 14 (a, c)); rostrum raised at high angle to frontal plane, facing laterally; mandibular portion semicircular, with blunt denticles at end; opesial portion smaller, semicircular; crossbar thin, complete. With age, frontal area proximal to orifice becomes raised and thickened; process atop avicularian chamber granulated like rest of frontal wall and ranging in size from a scarcely evident umbo, to a very tall (up to 0.65 mm), cylindrical process ( Figure 14 (d)). Ovicell ( Figure 14 (e)) hyperstomial, with wide opening; ooecium cup-like, often asymmetrically placed with respect to midline of maternal zooid; covered with secondary calcification, granulated like frontal wall. Aside from a single suboral avicularium per zooid, no other frontal or vicarious avicularia observed. Ancestrula not observed.

Remarks

Our material appears to be conspecific with specimens recently described and illustrated as C. pilaefera from Mauritius ( Hayward 1988), Vanuatu ( Tilbrook et al. 2001) and the Solomons ( Tilbrook 2006). Zooid size and all other characters are similar, with one glaring exception. In all other populations reported, colonies have large, spatulate vicarious avicularia, which are entirely lacking in our specimens. In some other populations, however, the vicarious avicularia have been noted as sparse ( Tilbrook et al. 2001) or rare ( Tilbrook 2006). It is noteworthy that in only one of 10 colonies did zooids develop tall, cylindrical suboral projections; zooids in the others either lacked a projection on the suboral avicularium or had only a small conical process.

Canu and Bassler (1929) originally described C. pilaefera from the Philippines. There has been no redescription of the type material, and some question remains ( Tilbrook et al. 2001) as to whether the material in the more recent studies mentioned above has been correctly attributed to C. pilaefera . The identity of Philippine material that Scholz (1991) identified as C. pilaefera is also questionable, as autozooids bear five conspicuous oral spines.

Occurrence

Celleporaria pilaefera was moderately common, with 10 colonies detected at the SES and REEF sites. This species is broadly distributed in the Indo-West Pacific, with the known range extending from Mauritius eastward to Vanuatu and the Solomon Islands, and as far northward as Okinawa.