Conescharellina diffusa, 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 : 153-154

Conescharellina diffusa sp. nov.

Figures 5D–F , 6A–B

Holotype. NMV F98989 , South Australia (no other details), from box labelled “ Bipora philippinensis ” in Maplestone’s hand.

Paratypes. NMV F101930 , South Australia, as above (3 colonies) .

Other specimens. NMV F101931, South Australia, Maplestone Collection (55 colonies); NMV F101932, Kangaroo Island, South Australia, Maplestone Collection (1 colony); NMV, F101933, probably NSW, Maplestone Collection (3 colonies); NMV F101934, stn BSS-065 (8 colonies, 5 with roots); NMV F101935, stn BSS-171 (1 colony); NMV F101936, stn SLOPE-49, (2 colonies); NMV F101937, stn GAB-020 (1 colony); NMV F101938, stn GAB-067 (1 colony); NMV F101939, stn GAB-069 (1 colony); NMV F101940, stn GAB-118 (3 colonies); NMV F101941, stn GAB-129 (2 colonies); NMV F98990, Dampier DA-2-37-01, North-western Australia (2 colonies, one with 8 ovicells, both with roots); NMV F101942, Dmitri Mendeleev collection, Tasmania (1 colony).

C. aff. diffusa : Specimens from the Tertiary of Victoria with very similar but not identical characters: Bairnsdale, NMV P311803 ( Fig. 5F ), P311804, plus 20 additional colonies; Muddy Creek (three colonies).

Etymology. diffusus (L.) – extended, dispersed, with reference to the wide distribution of this species.

Diagnosis. Conescharellina with large, often elongated, conical colonies, zooid orifices radial, surrounded by a rim of peristome. Root pores frequent, lunate, without avicularia. Avicularia in series alternating with orifices, small, rounded to subtriangular, bar without a ligula; non-palatal area with spinous processes. Ovicells fragile, with a wide ectooecial rim.

Description. Colony often large, conical, very narrow or domed, higher than wide. Zooid orifices apparently radial, alternating with radial series of rounded avicularia. Calcification smooth. Primary orifice with a fairly deep, round- ed sinus and paired condyles, surrounded by a peristome rim; adapical pore outside peristome. Ovicells fragile, with a wide ectooecial rim and a semitransparent entooecial frontal area. Avicularia paired, lateral and slightly adapical, or in series alternating with orifices. Orientation lateral and adapical; rostrum rounded to subtriangular, bar without ligula, but with 3 or more very fine, spinous processes on the non-palatal side. Antapical surface solid, with a small, central cancellate area. Lunate pores frequent, occurring in series with the avicularia but without any accompanying small avicularia.

Recent colonies with up to 28 zooid whorls and more than 14 zooids per whorl, height up to 5.0 mm, diameter 3.5 mm. Fossil colonies rounded, height 2.5 mm, diameter 3 mm.

Remarks. The Recent colonies are among the largest and most widely distributed of the Australian species examined. The avicularia appear to be unique in possessing small calcareous spine-like structures on the non-palatal side of the bar. Some zooids show evidence of the development of an ectooecial lamina surrounding the adapical pore; others appear to have also developed an entooecial layer above the pore ( Fig. 6B ). Usually, colonies are distinctly higher than wide but five of eight from Bass Strait (stn 64) are shorter and more rounded in outline. All five have long roots, in one case, anchored terminally to a fragment of a “scrupocellariid” bryozoan. The two colonies from north-western Australia are also conical but somewhat rounded; their avicularia show non-palatal spinous processes. One colony has eight fragile and only partially complete ovicells ( Fig. 5D ), showing that these have a very thinly calcified entooecium and a wider ectooecium than those of Trochosodon fecundus sp. nov. and C. stellata sp. nov.

Records of C. diffusa are widely separated. It ranges from north-west Australia to New South Wales , the west and central Australian Bight , South Australia , Bass Strait, and Tasmania , from 15 m. (north-west Australia) to 200 m. (Tasmania) .

The fossil colonies are much smaller and domed; their avicularia do not possess any non-palatal projections and it appears probable that, although closely related, they are not referable to C. diffusa sensu stricto ( Fig. 5F ). The specimen of “ Bipora cancellata ” from Bairnsdale described by MacGillivray (1895: 89, pl. 12 fig. 1; NMV P22727) appears to be conspecific with those listed here from Bairnsdale and Muddy Creek.

Figures

Figure 5. A–C, Conescharellina ecstasis sp. nov. A, NMV 98988. Adapical view, scale = 500 µm. B–C, NMV 98987, holotype. B, lateral view of colony, growth direction arrowed, scale = 1 mm. C, detail of adapical surface showing secondary calcification, avicularia and lunate root pore with three small avicularia, scale = 200 µm. D–F, Conescharellina diffusa sp. nov. D, NMV F98990. Adapical view of colony showing lunate root pores and broken ovicell (arrow), scale = 500 µm. E, NMV F98989, holotype. Lateral view of large colony, growth direction arrowed, scale = 1 mm. F. Conescharellina aff. diffusa sp. nov. NMV P311803, Bairnsdale, Victoria, Miocene. Lateral view of colony, scale = 500 µm.

Figure 6. Conescharellina diffusa sp. nov. NMV F98989, holotype. A, detail of zooid orifices with adapical pores, lunate root pores and avicularia with non-palatal spinules (arrow), scale = 200 µm. B, detail of orifices with adapical pores; orifice at left shows broken laminae of ectooecium and overlying entooecium of developing ovicell; orifice at right shows adapical pore surrounded by ectooecial lamina of ovicell (arrow). Note non-palatal spinules of avicularia, scale = 200 µm.