Flabellopora umbonata ( Haswell, 1881 )

Bock, Philip E. & Cook, Patricia L., 2004, A review of Australian Conescharellinidae (Bryozoa: Cheilostomata), Memoirs of Museum Victoria 61 (2), pp. 135-182 : 177

Flabellopora umbonata ( Haswell, 1881)

Figures 29A–C

Eschara umbonata Haswell, 1881: 41 , pl. 2 figs 5, 6.

Bipora umbonata . — Whitelegge, 1887: 345.— Livingstone, 1924: 209.— Livingstone, 1926: 98, pl. 5 figs 4, 5.

Bipora mamillata Maplestone, 1909: 270 , pl. 77 fig. 7.

Conescharellina mamillata . — Bretnall, 1922: 191.

Specimens examined. NMV F99395, stn SLOPE-40 (1 colony); NMV F101976, stn GAB-020 (2 young and 1 trilobed colony with roots, plus fragments); NMV F101977, stn GAB-030 (2 young and 2 trilobed colonies with roots, plus fragments); NMV F101978, stn GAB-045 (1 trilobed colony with roots, plus fragments); NMV F101979, stn GAB-056 (1 colony with fragments); NMV F101980, stn GAB-067 (1 trilobed colony); NMV F101981, stn GAB-074 (5 fragments); NMV F101982, stn GAB-084 (2 trilobed colonies plus fragments); NMV F101983, stn GAB-088 (1 colony plus fragments); NMV F101984, stn GAB-093 (1 large colony); NMV F101985, stn GAB-112 (1 colony); NMV F101986, stn GAB-117 (1 trilobed colony plus fragments); NMV F101987, stn GAB-119 (2 young and 3 trilobed colonies); NMV F101988, stn GAB-128 (1 trilobed colony); NMV F101989, stn SOELA-S03/84/74, E. Tasmania, 320 m (1 colony).

Description. Colony leaf-shaped, sometimes trilobed. Zooid frontal shield continuous, without zooid borders; calcification smooth with umbonate mamillae occurring among the orifices and the avicularia. Orifices almost circular, patent, with a rounded sinus, peristomial rim raised, narrow; adapical pores present. Avicularia small, rostra subtriangular or rounded, bar without a ligula. Septular pores rare, scattered. Root pores lunate, on the adapical edge, surrounded by thickened calcification.

Remarks. Livingstone (1924, 1926) and Harmer (1957) examined specimens from Queensland that were reported to be from Haswell’s original material, although only fragments of this were preserved. Maplestone’s (1909) type specimen of Bipora mamillata was unique but Livingstone (1924) mentioned “ types ” that may have had a different provenance. Both Livingstone and Harmer were convinced that F. umbonata was identical with B. mamillata, Maplestone (1909) however had noted some differences, both within Haswell’s suite of specimens and between them and his colonies from New South Wales.

The numerous specimens examined here are often slightly worn and very few possess roots. There are small differences among specimens but these seem to be the result of astogenetic position, ontogenetic thickening and wear. Some specimens have larger umbonate mamillae among orifices than others and some have larger avicularia but none of these differences is correlated with locality. The specimens from stations GAB-020, GAB-030 and GAB-119 include several very young colonies. These are lanceolate and consist principally of parallel series of antapically directed zooids with few laterally inclined series. Later growth illustrated the development of paired lateral laminae, giving the typically trilobed shape. One regenerated colony from station GAB-093 has a diameter of 28 mm and has developed nine thickened rays from an irregular central area. It is possible that other species of Flabellopora occur in Australian waters but have not yet been recognised.

Figures

Figure 29. A–C, Flabellopora umbonata (Haswell, 1881). NMV F99395, stn GAB-056. A. Colony, growth direction arrowed, scale = 1 mm. B. Antapical region showing orifices and avicularia, adapical pore arrowed, scale = 200 µm. C. Adapical region, root pore arrowed, scale = 1 mm.