Acanthodesia cf. irregulata ( Liu, 1992 ) Taylor & Tan, 2015

Taylor, Paul D. & Tan, Shau-Hwai Aileen, 2015, Cheilostome Bryozoa from Penang and Langkawi, Malaysia, European Journal of Taxonomy 149, pp. 1-34 : 9

Acanthodesia cf. irregulata ( Liu, 1992) comb. nov.

Fig. 3 G–L

cf. Membranipora irregulata Liu, 1992: 124 , figs 14–17.

Biflustra irregulata – Gordon et al. 2007: 46, fig. 1d.

Material

MALAYSIA: MSL BRY005, Pulau Betong, Penang, on oyster rafts. MSL BRY006, Balik Pulau, Penang, on plastic. MSL BRY007, BRY026, Batu Maung, Penang, on gastropod shells found among fishing debris.

Description

Colony encrusting, multiserial, unilamellar. Ancestrula twinned, proximally overgrown by later zooids in the example scanned. Autozooids subhexagonal, gently convex distally, 0.36–0.54 mm long by 0.22–0.30 mm wide; zooidal boundaries marked by a fine fissure; mural rim salient, narrow to moderately wide, pustulose; opesia occupying nearly all frontal surface, ovoidal, sometimes pear-shaped; gymnocyst absent or represented by low, rounded tubercles at proximal and proximolateral corners of zooids ( Fig. 3 K–L); cryptocyst narrow, broadest proximally where it forms a shallow planar shelf, variable in width laterally, pustulose. Kenozooids developed at growth irregularities, diamond-shaped, variable in size, opesia teardrop-shaped.

Remarks

Acanthodesia irregulata was originally described from the South China Sea and subsequently identified by Gordon et al. (2007) from Bangladesh. Two characteristic features were noted by Liu (1992): the presence of cuticular spinules on the frontal membrane and operculum, and tubercles at the proximal corners of some of the zooids. The former have not been observed in the studied material from Malaysia, which is bleached. However, tubercles do occur in some of the studied Malaysian specimens ( Fig. 3 K–L) and the size of the autozooids is very similar to that given by Gordon et al. (2007) in their Bangladeshi material. The paucity of taxonomic characters in the skeleton of the Malaysian specimens precludes certain identification as A. irregulata . It should also be noted that more than one species may be represented in Penang to judge from the variations in skeletal morphology; for example, tubercles can be present ( Fig. 3 K–L) or absent ( Fig. 3 G–J), and the width of the mural rim varies between specimens ( Fig. 3 G–L).

Figures

Fig. 3. Species of Acanthodesia. — A–C. A. cf. falsitenuis (Liu, 1992). Kampung Kuala Temoyong, Langkawi, MSL BRY003.A. Zooids. B. Detail. C. Cryptocystal process. — D–F. A. peramabulata (Louis & Menon, 2009). Pantai Pasir Hitam, Langkawi, MSL BRY004. D. Part of colony with overgrowth. E. Group of zooids. F. Wide zooid immediately before a row bifurcation. — G–L. A. cf. irregulata (Liu, 1992). Note variation between specimens in the width of the lateral mural rim, which is particularly broad in I, and the development of tubercles, present only in the colony shown in K and L. G. Pulau Betong, Penang, MSL BRY005. H–I. Batu Muang, Penang, MSL BRY026. J. Balik Pulau, Penang, MSL BRY006. K–L. Batu Maung, Penang, MSL BRY007. Scale bars: A, D = 1 mm; B, I, L = 200 μm; C = 50 μm; E–H, J–K = 500 μm.