Conescharellina cognata, Bock & Cook, 2004

Bock, Philip E. & Cook, Patricia L., 2004, A review of Australian Conescharellinidae (Bryozoa: Cheilostomata), Memoirs of Museum Victoria 61 (2), pp. 135-182 : 151

Conescharellina cognata sp. nov.

Figures 3C–G

Holotype. NMV F98985 , Maplestone collection, Kangaroo Island , South Australia, labelled “ Bipora angulopora ”.

Paratypes. NMV F101898 , locality as above (23 colonies) .

Other specimens. NMV F101899, Maplestone collection, South Australia (no details) (23 colonies); NMV F101900, stn BSS-55 (1 colony); NMV F101901, stn BSS-65 (1 colony); NMV F101902, stn BSS-117 (4 colonies with roots); NMV F101903, stn BSS-127 (1 colony); NMV F101904, stn BSS-130 (4 colonies); NMV F101905, stn BSS-132 (1 colony); NMV F101906, stn BSS-138 (1 colony); NMV F98986, stn BSS-155 (34 colonies); NMV F101907, stn BSS-158 (12 colonies); NMV F101908, stn BSS-159 (12 colonies); NMV F101909, stn BSS-161 (11 colonies); NMV F101910, stn BSS-162 (3 colonies); NMV F101911, stn BSS-170 (2 colonies); NMV F101912, stn BSS-171 (8 colonies); NMV F101913, stn BSS-176 (6 colonies); NMV F101914, stn BSS-194 (3 colonies); NMV F101915, stn GAB-019 (1 colony); NMV F101916, stn GAB-020 (5 colonies); NMV F101917, stn GAB-030 (3 colonies); NMV F101918, stn GAB-045 (2 colonies, one with root); NMV F101919, stn GAB-049 (1 colony with root and antapical coral); NMV F101920, stn GAB-067 (1 colony); NMV F101921, stn GAB-098 (2 colonies); NMV F101922, stn GAB-101 (1 colony).

Etymology. cognatus (L.) – related, referring to the similarities of the species with some descriptions of “ C. angulopora ”.

Diagnosis. Conescharellina with large, often flattened colonies; antapical surface flat or hollow, with large cancelli. Zooid orifices with a narrow sinus and large condyles. Avicularia large, lateral, interzooidal, with subtriangular rostrum orientated adapically and laterally. Root pores frequent, lunate.

Description. Colonies very large, usually flattened, occasionally conical, particularly early in astogeny. Calcification smooth. Zooids in irregular quincuncial series, tending to appear radial in very large colonies. Primary orifice an elongated oval with a narrow sinus and prominent condyles, peristome raised laterally and antapically but only a little adapically; adapical pore just outside, or on edge of the peristome. Avicularia interzooidal, lateral and adapical, large, rostrum subtriangular, directed adapically and laterally (usually in the same direction); bar with 1–3 ligulae. Lunate root pores frequent among orifices, apparently replacing avicularia, each with a pair of small lateral avicularia with a ligulate bar. Antapical surface with large, central cancelli, or hollow, covered by series of cancelli and minute avicularia. Proliferal region growing edge with prominent frontal shields visible at all stages of growth.

Colony diameter up to 10 mm, height 3 mm, number of whorls (radial) 18, number of zooids per whorl, at least 10.

Remarks. C. cognata differs from the accepted character of Maplestone’s concept of C. angulopora (see above) that it resembles in several features: its colony shape and the variable but generally slightly wider primary orifice. There is a variation in orifice shape between colonies from Bass Strait, where they are very narrow, and those from Southern Australia. The large avicularia can be seen at the growing edge to be interzooidal ( Fig. 3D ) and are usually consistently orientated in one direction within a single colony, although they vary within samples. The pair associated with each root pore is orientated laterally. Root pores are abundant, apparently replacing avicularia. In the larger colonies, the hollow antapical surface is completely covered by series of cancelli, interspersed with minute, rounded avicularia, totally unlike the solid surface of the conical colonies of C. angulopora (sensu Maplestone) .

C. cognata is common among the samples from GAB and BSS stations and in the Maplestone collection from South Australia. Gordon (1985, 1989) described and figured specimens from the Kermadec region and from New Zealand, that he assigned to C. angulopora . The colonies were not conical but flat. The antapical surface had no avicularia and a small central cancellate area. Gordon used an identical description for both sets of specimens and figured developing ovicells in one of the colonies from the Kermadec region (1985: fig. 23). Although closely similar to the colonies from South Australia, these specimens differ in the more elongated shape of the primary orifices and the characters of the antapical surface.

Figures

Fig.3. A–B, C. magniarmata Maplestone, NMV F98984. A, Lateral view of colony, growth direction arrowed, note adapical secondary calcification, scale= 1 mm. B, detail of orifice with adapical pore and avicularium, scale= 100 µm. C–G, Conescharellina cognata sp. nov. C–E. NMV F98985, holotype. C, lateral view of large colony, growth direction arrowed, scale = 2 mm. D, margin of proliferal region in antapical view, showing zooid orifices with adapical pores and “concealed” frontal shields with marginal septular pores. Chambers of alternating developing interzooidal avicularia arrowed, scale = 500 µm. E, detail of orifices with adapical pores, one with entooecial and ectooecial laminae of developing ovicell (arrow); large, interzooidal avicularia and lunate root pore with small paired avicularia, scale = 200 µm. F, NMV F98986, antapical view of small colony, showing central area of cancelli and alternating “concealed” zooids with marginal septular pores, scale = 500 µm. G. NMV F98985, holotype, detail of antapical surface of large colony, showing alternating series of cancelli, minute avicularia and extensions of septular pores, scale = 200 µm.