Trochosodon anomalus, 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 : 169-170

Trochosodon anomalus sp. nov.

Figures 24A–F

Holotype. NMV F99018 stn SLOPE-7.

Paratypes. NMV F99019 , stn SLOPE-7 (2 colonies) .

Other specimens. BMNH 1976.1.6.2, Challenger stn 185, Cape York, Australia, 279 m (26 colonies); NMV F101974, Challenger stn 185 (10 colonies).

Etymology. From anomalos (Gr.) – irregular, inconsistent, deviating, with reference to the combination of character states found in several genera, that are uniquely possessed by this species.

Diagnosis and description. Colonies very small, less than 2 mm in height and diameter but appearing to be higher than wide. Calcification mamillate. Zooids arranged in alternating whorls, each of 3 zooids, appearing to be in radial series; peristomes elongated and prominent. Primary orifice with a shallow, rounded sinus and paired condyles, adapical pore symmetrically placed on the edge of the peristome. Avicularia paired, lateral, widely separated from the orifices, alternating in radial series; rostra rounded, bar without a ligula. Adapical region with avicularia and small rounded pores; antapical region with a few avicularia only.

Colony diameter 0.5–1.5 mm, height 0.5–1.5 mm, number of whorls 2–4, number of zooids per whorl 3.

Remarks. Specimens of T. anomalus are of great interest as they include characteristics “typical” of both Trochosodon and Conescharellina ; in some features they even resemble species of Batopora , from which they are readily distinguished by the presence of an adapical pore. The arrangement of the radial series of avicularia suggests assignment to Conescharellina but the lack of basal cancelli and the presence of prominent, tubular peristomes allow its inclusion here with other species of Trochosodon .

The numerous colonies from Cape York indicate that the distribution of this tiny species extends from Queensland to New South Wales, from lower shelf to slope depths. The similarities between T. anomalus and T. asymmetricus are described above.

Figures

Figure 24. Trochosodon anomalus sp.nov. A–B, NMV F99018, holotype. A, lateral view of colony, direction of growth arrowed, scale = 500 _m. B, antapical view showing developing zooid, scale = 500 µm. C–D, BMNH 2003.11.27.2. C, lateral view of colony, growth direction arrowed, scale = 500 µm. D, antapical view, scale = 500 µm. E–F, NMV F99018, holotype. E, adapical region showing root pores and avicularia, scale = 200 µm. F, detail of orifices and avicularia, scale = 200 µm.