Scrupocellaria sinuosa Canu & Bassler, 1927

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 : 39-42

Scrupocellaria sinuosa Canu & Bassler, 1927

( Figures 7 , 8 )

Scrupocellaria sinuosa Canu & Bassler, 1927: 4 , pl. 1, figs 4–5.? Scrupocellaria spatulata: Ryland & Hayward, 1992: 237 , fig. 9.

Material examined. Holotype: NMNH 8426, Albatross Station 3999, Pacific II, vicinity of Kawai Island, Hawaii. Other material examined: MTQ G25291, Nelly Bay, Magnetic Island, off Townsville, 19.17215° S, 146.84733° E, 24 May 2011, 5 m, coll. KJT; MTQ G26019, 23.45496° S, 151.92351° E, 25 November 2010, 10 m, coll. KJT.

Description. Autozooids at very slight angle to each other, alternating and imposing a jagged appearance to the branch profile, in short internodes of generally 4–6 autozooids (up to seven in holotype); autozooids gracile, 0.370–0.508 mm (0.392±0.041) long, 0.133–0.147 mm (0.139±0.005) wide, with smooth, extensive proximal gymnocyst, approximately equal to 1.5–2 times area of elongate-oval opesia, cryptocyst very narrow and smooth. Scutum originating from just proximal of mid-point of inner lateral margin of opesia, most often oval or eggshaped, covering approximately half opesial area, distal lobe slightly larger than proximal lobe. Two (rarely three) inner (medial) orificial spines, four outer orificial spines, long, the most proximal spines shortest, directed frontally and distorting the opesial margin, the remaining three outer spines longest (ca 0.5 mm) disto-frontolaterally directed, six spines in axial autozooids. Lateral avicularia dimorphic: only small lateral avicularia present in Hawaiian material, on distolateral corner of all autozooids, laterally directed, perpendicular to autozooidal surface, with smooth-edged triangular rostrum and hooked tip, mandible triangular, with an acuminate, hooked tip; in Queensland specimens the small lateral avicularia are sometimes replaced by an enlarged avicularium, rostrum trifoliate, orientated parallel to zooidal axis. Frontal avicularia rarely present in Queensland material, but common in Hawaiian material, small, aquiline, obliquely directed frontoproximally. Ovicells almost globular, about 0.200 mm long and 0.145 mm wide, with 9–15 small ectooecial pores. Single axial vibraculum; other vibracula projecting distal to opesia, 0.123–0.134 mm (0.131±0.003) long, visible frontally, drop-shaped, slit-shaped setal groove directed proximomedially, setae long (ca 1mm). A rhizoid foramen present in proximal wall of all lateral vibracula, not axial vibraculum; rhizoids usually only present at base of branch.

Remarks. Scrupocellaria sinuosa is characterised by its alternating autozooids, its extensive gymnocyst, its oval scutum, small frontal avicularia, small lateral avicularia sometimes replaced by an enlarged trifoliate avicularium and long non-bifurcating spines.

Scrupocellaria sinuosa was characterized by Canu & Bassler (1927) by its pyriform scuta and the presence of one inner and three outer spines. However, autozooids in the holotype (NMNH 8426; see Figure 7 ) have three or four outer and one or two inner distal spines, similar to those observed in the Queensland specimen. The Queensland colony differs from those from Hawaii in the presence of enlarged trifoliate lateral avicularia replacing the small ones (see Figure 8 E).

The trifoliate lateral avicularia are also found in Scrupocellaria spatulata (d’Orbigny, 1851) . He named the species based on Red Sea specimens figured by Savigny (1817, pl. 12, fig 1.1–1.7), but neither type specimens nor description accompanied Savigny’s illustrations. Harmer (1926) redescribed S. spatulata based on Indo-Pacific material, synonymizing S. pusilla Smitt, 1872 within it, based on its size and the position of the lateral avicularia ( Osburn 1940). Scrupocellaria spatulata has been reported from several localities in tropical and subtropical waters, e.g. Komodo Island, Indonesia ( Winston & Heimberg 1986), Heron Island, Australia ( Ryland & Hayward 1992), New Caledonia (d’Hondt & Gordon 1996) and Vanuatu ( Tilbrook et al. 2001). Winston & Heimberg (1986) characterised this species by zooids with 4–5 distal spines, smaller frontal scuta than those of S. sinuosa , and the absence of dimorphic lateral avicularia. Ryland & Hayward (1992), however, described enlarged slender avicularia with digitate rostra in those specimens found from Queensland. In addition, the specimen figured by d’Hondt & Gordon (1996, fig. 6F, G) is distinguished by the shape of the frontal scutum from the other specimens previously assigned to S. spatulata . Both Heron Island and New Caledonian specimens require re-examination and probably belong to distinct species. In addition, the examination of specimens assigned to S. spatulata at the NHMUK has revealed that at least four further distinct species have been misidentified as S. spatulata , each characterised by the size of the autozooids, the size of their scuta, the size and position of the basal vibracula, the shape and size of lateral avicularia, the presence of rhizoidal pores on the axial vibracula and the number of oral spines.

Recently, d’Hondt (2006) used the name Scrupocellaria muricata ( Lamouroux, 1816) for Savigny’s plates ( Savigny 1817, pl. 12, figs 1.1–1.7). However, examination of specimens from Japan identified as Crisia muricata by Lamouroux (1816) (MNHN 19680) reveals that this species is neither conspecific nor congeneric with S. spatulata from the Red Sea. Instead this species belongs to a complex of morphologically similar species nominally assigned to Tricellaria occidentalis auctt . These species are characterised by irregular frontal scuta and no basal vibracula. Since it is not possible to determine type material for d’Orbigny’s species, S. spatulata , we use the name Scrupocellaria sinuosa for Australian material.

Scrupocellaria sinuosa is similar to Scrupocellaria hamata n. sp. (below) in its overall appearance; these species differ in the sizes of their autozooids, lateral avicularia and vibracular chambers.

Distribution. Scrupocellaria sinuosa was originally described from Hawaii at 12–270 m depth. A single specimen was recently collected from Nelly Bay, Magnetic Island, off Townsville, Queensland (5 m depth), whilst another was found at Heron Island.

S. sinuosa has also recently been found from Lizard Island, GBR (Tilbrook pers. obs.).

Figures

FIGURE 7. Scrupocellaria sinuosa Canu & Bassler, 1927. A – B, NMNH 8426, Holotype. A, frontal surface of bifurcating branches; note the presence of frontal avicularia and ovicells. B, basal surface at branch bifurcations; note the positions of the vibracular chambers and the single axial vibraculum. Scale bars: 500 µm (A, B).

FIGURE 8. Scrupocellaria sinuosa Canu & Bassler, 1927. A – D, MTQ G 25291; E, MTQ G 226019. A, frontal view of colony with dimorphic lateral avicularium; note the paucity of frontal avicularia. B, frontal view of branch bifurcation. C, basal surface at branch bifurcation; note the single axial vibraculum. D, basal surface of branch showing a vibracular chamber adjacent to a lateral avicularium. E, ovicelled zooids proximal to a branch bifurcation; note the distinctive lateral avicularium at lower right. Scale bars: 500 µm (A); 100 µm (B – D); 200 µm (E).