Scrupocellaria cervicornis Busk, 1852a

Tilbrook, Kevin J. & Vieira, Leandro M., 2012, Scrupocellaria (Bryozoa: Cheilostomata) from the Queensland coast, with the description of three new species, Zootaxa 3528, pp. 29-48 : 34

Scrupocellaria cervicornis Busk, 1852a

( Figure 4 )

Scrupocellaria cervicornis Busk, 1852a: 370 ; Busk, 1852b: 24, pl. 62, figs 1–4. Scrupocellaria diadema: Harmer, 1926 (part): 375.

Material examined. Holotype: NHMUK 1854.11.15.81, off Cumberland Island, Queensland, 46 m, fine grey mud, ca 20.57° S, 149.13° E. Other material examined: MTQ G25339, Site 2214, Sample Id 0 20636, SBD 0 13855, Great Barrier Reef, 21.235° S, 151.745° E, 25 May 2004, 45 m.

Description. Autozooids at slight angle to each other, partially back to back; gracile, 0.370–0.410 mm (0.382±0.014) long and 0.197–0.235 mm (0.212±0.013) wide, with smooth, proximal gymnocyst approximately one quarter of large oval opesia; cryptocyst smooth and very narrow. Scutum originating from midway along inner lateral margin of opesia, very robust and covering most of membranous area, shield-shaped, or bifurcated and heart-shaped, the distal edge flaring out frontally, the proximal lobe of the scutum larger than the distal lobe. Two inner spines, and two outer orificial spines, very short, the two most proximal spines distorting the gymnocystal/ cryptocystal rim, directed frontally and bifurcating; a fifth distomedial spine in non-brooding autozooids. Avicularia of two types: lateral avicularia, very small, 0.039–0.065 mm (0.046±0.009) long, on distolateral corner of all autozooids (except axial autozooid), distolaterally directed, with straight-edged triangular rostrum, the mandible curved basally with a sharp, hooked tip; frontal avicularia on most zooids, originating proximal to cryptocystal rim on inner side of zooid, directed distomedially, small and similar in shape to lateral avicularia but raised on a tubular base. Ovicells smooth, 0.115–0.173 mm (0.147±0.021) long and 0.188–0.225 mm (0.210±0.012) wide, with 2–5 circular or elongate oval raised pores. Single axial vibraculum, other vibracula projecting laterally, 0.182–0.192 mm (0.185±0.004) long, visible frontally, spatulate setal groove directed proximomedially, seta long, curving across more than width of branch. A rhizoid foramen is present in proximal wall of all lateral vibracula, but not on axial vibraculum; however, rhizoids usually only present at base of branch.

Remarks. Scrupocellaria cervicornis zooids are characterised by a large shield-shaped or heart-shaped scutum, very small lateral avicularium and often-seen raised, frontal avicularium. Scrupocellaria cervicornis is distinguished from S. diadema by its shorter zooids, a large scutum in both ovicellate and non-ovicellate zooids and frontal avicularium with a shorter base.

Distribution. Originally described from the Whitsunday Group of islands off the Queensland coast, north of Mackay ( Busk 1852a), Scrupocellaria cervicornis has not been recorded since. This is not surprising as Harmer (1926) synonymised it within S. diadema (see notes above). A second specimen was found southeast of the type locatity, and this is only the second record of the species.

Figures

FIGURE 4. Scrupocellaria cervicornis Busk, 1852 a. A – D, MTQ G 25339. A, frontal surface of brooding colony. B, oblique view of basal surface; note the shape of the vibracular chambers. C, frontal surface of brooding zooids at branch bifurcation. D, basal surface at branch bifurcation. Note the spatulate setal groove. Scale bars: 500 µm (A); 100 µm (B, C – D).