Sinoflustra amoyensis ( Robertson, 1921 )

Taylor, Paul D. & Tan, Shau-Hwai Aileen, 2015, Cheilostome Bryozoa from Penang and Langkawi, Malaysia, European Journal of Taxonomy 149, pp. 1-34 : 11-12

Sinoflustra amoyensis ( Robertson, 1921)

Fig. 5 D–F

Membranipora amoyensis Robertson, 1921: 49 , fig. 6.

Sinoflustra amoyensis – Liu & Yang 1995: 349, figs 1–2.

Material

MALAYSIA: MSL BRY010, Batu Muang, Penang, encrusting a barnacle from debris adjacent to a fishing jetty.

Description

Colony encrusting, multiserial, unilamellar. Ancestrula and early astogeny not observed. Autozooids subrectangular, rounded distally, slender, typically twice as long as wide, 0.43–0.63 mm long by 0.18–0.28 mm wide; zooidal boundaries marked by a narrow fissure; opesia occupying two-thirds of frontal surface, elongate inverted pear-shaped; cryptocyst convex, widest proximally, narrowing distally, covered by small pustules, about 10–16 cryptocystal spinules extending from mural rim over proximal two-thirds of opesia, but not meeting, distal third of opesia broad and spineless ( Fig. 5F ); gymnocyst lacking. Spines present at distolateral corners of autozooids, spines broken off in studied specimens, leaving a small rounded triangular base with a central pore ( Fig. 5F ). Avicularia not observed.

Remarks

The original figure of Robertson (1921: fig. 6) shows zooids with branching spines at the distolateral corners. Although spines are not preserved in the studied material from Penang, their bases are clearly visible in these locations. Robertson’s Chinese material also has slightly shorter cryptocystal spinules and the opesia is ellipsoidal in outline compared with the elongate inverted pear-shaped opesia of the Penang specimens. However, Liu et al. (2001: pl. 18, fig. 3) figured a Chinese specimen of S. amoyensis with longer spinules and opesia that broaden distally. A putative colony of this species epizoic on a turtle has broader autozooids and short cryptocystal spinules ( Frazier et al. 1992: fig. 1). In view of the morphological variability encompassed by specimens assigned to the species, the Penang material can be identified as S. amoyensis .

Not seen in the Malaysian specimens, but sporadically developed elsewhere in this species, are vicarious avicularia (e.g., Liu et al. 2001: pl. 18, fig. 3). These are longer and wider than the autozooids, and the distal part of the opesia is particularly broad, raised slightly and separated from the proximal part by two small, condyle-like indentations.

Figures

Fig. 5. — A–C. Arbopercula sp. Pulau Betong, Penang, MSL BRY009. A. Group of zooids. B. Zooids showing spines. C. Distal end of a zooid with a pair of oral spines and the proximal circumopesial spine of the next distal zooid. — D–F. Sinoflustra amoyensis (Robertson, 1921). Batu Muang, Penang, MSL BRY010. D. Part of a colony. E. Detail of a group of zooids at the broken edge. F. Opesia and cryptocystal spinules. Scale bars: A, D = 500 μm; B, E = 200 μm; C, F = 100 μm.