Cellaria boninensis Silén, 1938

Martino, Emanuela Di, 2023, Scanning electron microscopy study of Lars Silén’s cheilostome bryozoan type specimens in the historical collections of natural history museums in Sweden, Zootaxa 5379 (1), pp. 1-106 : 54-56

Cellaria boninensis Silén, 1938

( Fig. 28 ; Table 26)

Cellaria boninensis Silén, 1938: 353 , text-figs 45, 46, 76–80, pl. 17, fig. 121.

Material examined. Lectotype (designated here) UPSZTY 2477 A, the best preserved specimen among syntypes UPSZTY 2477 A–D, Bonin Islands (Ogasawara), Japan; depth 45–60 m. Leg. Prof. S. Bock 1914 . Paralectotypes: the remaining specimens.

Description. Colony erect, flexible, jointed, dichotomously branching ( Fig. 28A ); internodes straight and cylindrical, 260–320 µm wide ( Fig. 28B, C ).

Autozooids hexagonal to lozenge-shaped, longer than wide (mean L/ W 1.86), distinct, separated by a slightly raised outline, alternately arranged in whorls of four ( Fig. 28D ); cryptocyst finely and densely granular, concave, depressed centrally and rising peripherally, forming an inner ridge concentrical to zooidal outline but more rounded, oval to rhomboidal ( Fig. 28A–D ).

Orifice placed centrally or slightly more distally, wider than long, occupying c. one-eighth of the zooidal frontal length (mean OpL/ZL 0.12), semicircular with proximal margin markedly convex and a pair of blunt proximolateral condyles ( Fig. 28D, F )

Avicularia vicarious, rare, usually two per internode; outline and cryptocyst similar to those of autozooids; rostrum 150–170 µm long, raised, slightly curved and asymmetrical, with rounded tip ( Fig. 28E ); mandible same shape and length as the rostrum.

Ovicells absent in the present material. Reparative frontal and intramural budding observed in some autozooids (e.g. Fig. 28D ).

Remarks. Although in the first description of this species there is no designation of type specimens ( Silén 1938), this appears later in Silén (1941, p. 70) in which numerous detached colonies from locality 35 are indicated as the type material. There is also a discrepancy between the depth indicated by Silén (1938, 1941) in the locality paragraph of the species description (100–120 m) and the depth of locality 35 (45–60 m) as reported in the list of localities by Silén (1941, p. 3).

Hastings (1947), followed by Whitten (1979), listed this species as a synonym of C. tenuirostris ( Busk, 1852b) , considering that the long, narrow zooids mentioned as the main difference between the two species by Silén (1938) was not a reliable specific character, and adding that Silén might be misled by Busk’s figure (1852b, pl. 53, fig. 4), representing C. bicornis and not C. tenuirostris . However, the two species also differ in the avicularium rostrum: straight, symmetrical, thin and pointed (i.e. needle-shaped) in C. tenuirostris (e.g. Gordon 1984, pl. 18B; Achilleos et al. 2020, table 2); slightly curved and asymmetrical, wider and rounded in C. boninensis (see Fig. 28E ).

This species has also been reported in the South China Sea ( Gordon 2016).

Figures

FIGURE 28. Cellaria boninenis Silén, 1938. Lectotype (designated here) UPSZTY 2477A, Bonin Islands, Japan. A. View of internodes at branch bifurcation. B, C. Close-up of each internode in (A). D. Close-up of autozooids, the one at the bottom showing zooid reparation by intramural budding. E. Close-up of the avicularium. F. Close-up of the orifice. Scale bars: A–C = 500 µm; D = 200 µm; E = 100 µm; F = 20 µm.