Conescharellina obscura, 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 : 154-155

Conescharellina obscura sp. nov.

Figures 7 , 8A–C

Bipora philippinensis . — Maplestone, 1910: 6, pl. 1 figs 2, 2a (not

Busk, 1854).

Holotype NMV F98991 , stn BSS-155 .

Paratype NMV F98992 , stn BSS- 155.

Other specimens. BMNH as C. philippinensis , 1909.11.12.12 and 13, Green Point, Port Jackson, NSW (Maplestone Collection, possibly from Whitelegge’s material, 2 colonies with ovicells); BMNH 1899.5.1.1148, Port Jackson (Hincks Collection, 5 colonies); BMNH, as L. cancellatus , 1934.10.20.88, Port Stephens, NSW (Vine Collection, 2 colonies); NMV F101943, stn GAB- 048; (1 colony with ovicells); NMV F101944, stn GAB- 074; (3 colonies); NMV F101945, stn GAB- 108 (1 colony); NMV F101946, stn GAB- 113 (2 colonies); NMV F101947, stn GAB- 118 (2 colonies); NMV F101948, stn GAB-131 (1 colony); NMV F101949, Dampier DA-2-09-02 (1 colony with root); NMV F101950, Dampier DA-2-73-01 (2 colonies with roots).

Etymology. obscura (L.) – hidden, referring to the confusion of records with those of C. cognata , C. stellata and C. philippinensis .

Diagnosis. Conescharellina with flat, often large colonies. Zooid orifices oval with a short sinus, peristomes not prominent. Avicularia rounded, lateral and antapical, near the orifice, bar with 1–3 ligulae. Root pores lunate. Ovicells globular, very fragile, with an extensive area of entooecium frontally.

Description. Colony fairly flat, even lenticular, distinctly wider than high. Zooid orifices quincuncial, sunken in surrounding peristome, that is not prominent. Orifice oval, with a short, rounded sinus and small condyles. Adapical pore within peristome calcification. Avicularia rounded, lateral and antapical near the orifice, bar with 1–3 ligulae. Lunate root pores frequent adapically, with 1, occasionally 2, lateral avicularia. Antapical surface covered with small cancelli.

Colonies up to 14 mm in diameter but usually much smaller, maximum number of zooid whorls estimated as 15, and zooids per whorl 20.

Remarks. The close but superficial similarity in colony form means that records of this species were originally confused with those of C. cognata , that also has large, flat colonies with numerous antapical cancelli. The colonies from the GAB stations are very large, ranging from 9 to 12 mm in diameter and are hollow antapically; those from stns GAB- 074 and GAB- 118 are more domed and nearly solid antapically. In the smaller colonies from stn BSS- 155, the lunate root pores are present but they are very rare or absent from the large colonies. Again, this is in contrast to C. cognata , where they are common throughout colony growth. Although the large, flat colonies resemble those described in “ C. crassa ” by Tenison Woods (1880), they differ in orifice shape and the types of avicularia and root pores present. Antapical oral avicularia are also found only in C. pustulosa , from which C. obscura differs in colony shape and size, orifice shape and form of the antapical cancelli. Whitelegge (1887) described specimens from Port Jackson as Bipora philippinensis , with a depressed conical shape and orifices with a wide sinus. Avicularia with subcircular mandibles occurred in pairs and sometimes on the antapical side of each orifice. The antapical surface had cancelli and avicularia. Ovicells were present and were “globose and smooth, with a faint fimbriated stigma in front.”

Colonies referred to this species were observed alive by Whitelegge (1887: 347) for three days. He noted pairs of “tubular filaments” attached to annelid tubes and to fragments of shell. He thought that these roots originated from avicularia and did not recognise the function of the lunate root pore that he also reported. Maplestone (1910: 6, pl. 1, fig. 2) illustrated ovicells in specimens of Whitelegge’s material that he also referred to C. philippinensis but noted that he could see no frontal stigma. Maplestone’s specimens from Port Jackson, in the BMNH collection, are probably part of Whitelegge’s material and are here referred to C. obscura sp. nov., whereas those in the NMV collection from South Australia, also labelled Bipora philippinensi s, are here assigned to another new species, C. diffusa . The two slides from Green Point (1909.11.12.12 and 13) each contain a single, fairly flat colony, less than 2.5 mm in diameter, with most of the opercula and mandibles intact. They each include two fragile ovicells and up to eight partially developed ovicells. These are globular, like those figured by Maplestone (1910). They appear to have an extensive area of frontal entooecial calcification and a series of minute pores close to the ovicell base, that may mark the limit of the ectooecium. There is no sign of any striations or a “stigma”. The other, smaller specimens from the BMNH collections are obviously conspecific but have no ovicells. They too, have most of the opercula and mandibles present; only one preparation shows the primary orifice clearly. One of the five specimens from Port Jackson ( Fig. 8C , Hincks collection, BMNH 1899.5.1.1148) is similar in characters to specimens from Bass Strait ( Fig. 8B , stn BSS- 155) except for the greater width of the orifice sinus. C. obscura occurs from north-west Australia and across the Great Australian Bight to New South Wales, from a depth range of 12 to 125 metres.

Figures

Figure 7. Conescharellina obscura sp. nov. A, NMV F98991, holotype. Lateral and adapical view of large colony, scale= 500 µm.

Figure 8. Conescharellina obscura sp. nov. A–B, NMV P98992. A, adapical view of small colony, showing lunate root pores, scale = 500 _m. B, detail of zooid orifices, avicularia, and one lunate root pore, scale = 200 µm. C, BMNH 1899.5.1.1148, Hincks Collection, Port Jackson, New South Wales. Detail of zooid orifices with adapical pores, avicularia and one lunate root pore. Note the wide orifice sinuses, scale = 200 µm.