Conescharellina multiarmata ( Maplestone, 1909 )

Bock, Philip E. & Cook, Patricia L., 2004, A review of Australian Conescharellinidae (Bryozoa: Cheilostomata), Memoirs of Museum Victoria 61 (2), pp. 135-182 : 148

Conescharellina multiarmata ( Maplestone, 1909)

Figures 2C–F

Bipora multiarmata Maplestone, 1909: 268 , pl. 75 figs 2a, b.

Conescharellina multiarmata .— Livingstone, 1924: 212.

not Trochosodon multiarmatus . — Gordon, 1989: 83, pl. 49 D–F (= Trochosodon gordoni sp. nov., see below).

Specimens examined. BMNH 2000.2.23.4; (3 colonies, part of material sent by Maplestone to the BMNH, labelled “cotypes”); NMV F98981 , probably NSW (31 small colonies from two boxes labelled by Maplestone, probably part of type material) ; NMV F101884 , stn BSS-169 (1 colony) ; NMV F101885 , stn BSS-170 (1 colony) ; NMV F98982 , F98983 , stn SLOPE-2 (20 colonies, 4 with roots, 2 with corals on antapical side) ; NMV F101886 , stn SLOPE-7 (1 colony) ; NMV F101887 stn SLOPE-39 (2 colonies) ; NMV F101888 , stn SLOPE-40 (47 colonies) ; NMV F101889 . stn SLOPE-48 (1 colony) ; NMV F101890 , stn GAB-030 (1 colony) .

Description. Colony conical, higher than wide. Calcification smooth to finely mamillate. Orifices in radial series, small, elongated, with a small sinus flanked by distinct condyles, and a raised lateral peristome. Adapical pore obviously tubular, opening on the inside of the peristome edge. Avicularia very small, rounded, 4 placed laterally and 1 proximolaterally near the orifice sinus; bar with a minute ligula. Frontal pores minute, forming a pattern among the orifices. Antapical surface solid with pores and small avicularia at maturity; marginal peristome with small paired avicularia. Lunate root pores in radial series with the zooid orifices, present towards the adapical region of the colony.

Colonies 1.9–2.2 mm in height and 1.8–2.2 mms wide. They comprise approximately 4–12 or more astogenetic generations, arranged radially, and include 8–10 zooids per whorl. The numerous colonies from the SLOPE stations are wider than those from Maplestone’s collection, inferred to be from New South Wales. Mature colonies may show a small central area of cancelli on the antapical surface.

Remarks. C. multiarmata differs from C. biarmata , that also has very small colonies, in the details of the primary orifice and character and distribution of the minute avicularia. These alternate with minute frontal pores and have a rounded rostrum; the bar has a single small ligula. Paired avicularia are visible on the antapical surface of marginal zooids but are not as prominent as those of C. eburnea . In some zooids, the adapical pore is prominent and a tubular extension of its calcification can be seen to descend into the peristome, like that of Trochosodon asymmetricus ( Fig. 2D ). The colonies from the SLOPE stations are generally larger than those from the Maplestone collection. A colony from stn SLOPE-2 has an incorporated antapical solitary coral present ( Fig. 2F ).

Gordon (1989) identified specimens from New Zealand as Maplestone’s species and assigned them all to Trochosodon . The New Zealand material appears to be referable to Trochosodon but certainly not to Conescharellina multiarmata : it is here renamed Trochosodon gordoni sp. nov.

Figures

Figure 2. A–B, Conescharellina biarmata (Maplestone, 1909). NMV F98980. A, lateral view of colony, growth direction arrowed, scale=1 mm. B, detail of orifices with adapical pore, avicularia and slit-like frontal septular pores, scale= 100 µm. C–D, Conescharellina multiarmata Maplestone, NMV F98981. C, Lateral view of colony, growth direction arrowed, scale=500 µm, D, detail of orifices from slightly antapical view, showing tubular adapical pores, avicularia and minute frontal septular pores, scale = 200 µm. E–F, Conescharellina multiarmata (Maplestone, 1909). E, NMV F98983, orifices and avicularia; note pattern of septular pores, scale= 200 µm. F, NMV F98982, Antapical view of colony showing small solitary coral. Note paired, marginal peristomial avicularia, scale= 500 µm.