Cupuladria guineensis ( Busk, 1854 )

Martino, Emanuela Di & Taylor, Paul D., 2018, Early Pleistocene and Holocene bryozoans from Indonesia, Zootaxa 4419 (1), pp. 1-70 : 14-15

Cupuladria guineensis ( Busk, 1854)

( Figs 25–28 ; Table 8)

Cupularia guineensis Busk, 1854: 98 , pl. 114, figs 1–5.

Cupuladria guineensis: Harmer, 1926: 266 , pl. 16, figs 5–7; Cook, 1965: 170, pl. 1, figs 1, 2, pl. 2, figs 3, 4.

Figured material. RGM.1350551, Holocene, UPGG 041, off South Sulawesi.

Description. Colony free-living, small, 2–5 mm in diameter, flattened to slightly convex, discoidal. Ancestrula elliptical, smaller than later autozooids, about 270 µm long by 150 µm wide, and with less developed cryptocyst, surrounded by seven autozooids. Autozooids distinct owing to their raised margins, arranged in alternating, radial rows, rounded rhomboidal to pentagonal, longer than wide (mean L/W = 1.28). Gymnocyst smooth, reduced to a narrow, raised rim distally and distolaterally. Cryptocyst well-developed proximally and laterally, reduced distally, sloping steeply inwards, tuberculate, with rounded or pointed denticles projecting into the opesia from the lateral edges giving it a denticulate appearance. Opesia irregularly oval to subrectangular, occupying half to two-thirds of the zooidal frontal surface; a variable number of circular, septular pores visible through the opesia. An auriform vibraculum distal to each zooid, asymmetrical, proximolaterally directed, oriented alternatively to left and right. Vicarious avicularia absent. Dorsal side tuberculate, divided into hexagonal sectors intermittently divided by radial boundaries, each pierced by 2–6 small, circular pores. Granular, lace-like closure plates develop below the level of the cryptocyst in central zooids.

Remarks. Two hundred and sixty-five specimens of Cupuladria guineensis were found in our samples. This species is distinguished from other species of Cupuladria by the pattern of the basal sector boundaries and the broader extent of the cryptocyst ( Cook 1965). After the re-examination of a large number of specimens, and based on the characters of the basal sectors, Cook (1965) recognized two groups roughly corresponding to two geographical areas: a first more ‘northern’ group with tuberculate hexagonal sectors, and a second Australian group with smooth, quadrilateral sectors. It seems likely that fossil and modern records of C. guineensis belong to a cryptic species complex. Morphometric and genetic analyses from the numerous populations are needed to confirm its status.

N, Number of colonies and number of zooids measured; SD, standard deviation.

Figures

FIGURES 25–28. Cupuladria guineensis (Busk, 1854), RGM.1350551, Holocene, UPGG041, off South Sulawesi. 25. General view of the colony. 26. Close-up of the ancestrula and early astogeny with closure plates. 27. Close-up of autozooids and vibracula at the colony edge. 28. General view of the basal surface showing the hexagonal sectors. Scale bars: Fig. 25 = 600 µm; Fig. 26 = 200 µm; Fig. 27 = 100 µm; Fig. 28 = 1 mm.