Acanthodesia perambulata ( Louis & Menon, 2009 ) 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 : 8

Acanthodesia perambulata ( Louis & Menon, 2009) comb. nov.

Fig. 3 D–F

Biflustra perambulata Louis & Menon, 2009: 61 , figs 2–7.

Material

MALAYSIA: MSL BRY004, Pantai Pasir Hitam, Langkawi, on floating plastic washed ashore.

Description

Colony encrusting, multiserial, unilamellar, locally multilamellar ( Fig. 3D ). Ancestrula and early astogenetic stages not observed. Autozooids rounded rectangular, gently convex distally, 0.43–0.60 mm long by 0.30–0.50 mm wide, the first zooids in new rows narrow and about 2 × longer than wide, later zooids becoming progressively broader until approximately equidimensional immediately before row bifurcation ( Fig. 3F ); zooidal boundaries marked by a fine fissure; mural rim salient, narrow, pustulose; opesia occupying nearly all frontal surface, ovoidal; gymnocyst lacking; cryptocyst narrow, broadest at proximolateral corners, planar, with sporadic pustules that increase in abundance and become dense around edge of opesia; no spine bases, spinules or tubercles. Kenozooids developed at convergences between colony lobes, variable in shape and size, opesia ovoidal.

Remarks

This species was originally described from Cochin, India, where colonies are erect and bilamellar, unlike the encrusting colonies from Langkawi assigned here to Acanthodesia perambulata . However, the skeletal morphology and dimensions of the autozooids is almost identical in the Indian and Malaysian material and it is known that a single species can exist as either encrusting or erect bifoliate colonies. Tilbrook & Gordon (2015) list this species (as Biflustra perambulata ) from the Straits of Johor, Singapore. Compared to the similar species Acanthodesia grandicella Canu & Bassler, 1929 (e.g., Gordon et al. 2008; Tilbrook 2012), A. perambulata has smaller zooids that are less granular and have weaker calcification. Nevertheless, molecular sequence data is needed to show that these fouling invasive species really are distinct from one another.

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.