Parasmittina raigioidea Liu et al., 2001

Fig. 12 A–C

Parasmittina raigioidea Liu et al., 2001: 629, pl. 58, figs 1–2.

Material

MALAYSIA: MSL BRY020b, Pulau Betong, Penang, encrusting barnacle on oyster raft.

Description

Colony encrusting, multiserial, unilamellar. Ancestrula and early astogeny not observed. Autozooids subhexagonal, distally rounded, about 0.24–0.51 mm long by 0.19–0.27 mm wide; boundary walls salient with a fine fissure; frontal shield convex, coarsely pustulose, about 20 marginal areolar pores separated by ridges, impinging on central part of shield in older zooids, no pseudopores; primary orifice elliptical, about 0.09 mm long by 0.10 mm wide, lappets developed laterally, lyrula broad, about 9 μm high by 25 μm wide at top edge, condyles present about one-quarter along orifice; oral spine bases numbering 1 or 2; ovicell not observed. Avicularia adventitious, variable in size, shape and orientation but not clearly polymorphic (i.e., intermediates existing between common morphologies); usually located lateral to orifice or on proximal frontal shield, the former directed proximally, the latter distally or laterally, 0.08–0.23 mm long by 0.05–0.08 mm wide; rostrum acutely triangular to spatulate with a moderate shelf, straight or slightly curved; cross-bar calcified, straight to concave; opesia semielliptical.

Remarks

Acknowledging the problems in discriminating between species of Parasmittina, this material is tentatively assigned to P. raigioidea, a species described originally from South China, on account of the similar range of avicularian morphologies to those seen in pl. 58, figs 1 and 2 of Liu et al. (2001). These authors recognised two types of small avicularia – triangular and spatulate – as well as giant avicularia.

The Malaysian material shows a range of avicularian morphologies and sizes and it is unclear whether there is one highly variable type of avicularium or several polymorphs.