Trochosodon asymmetricus, 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 : 167-168

Trochosodon asymmetricus sp. nov.

Figures 18, 19A–C

Holotype. NMV F99010 , stn SLOPE-6 (colony with root).

Paratypes. NMV F99011 (figured), stn SLOPE-6 (1 worn colony) . Other specimens. NMV F101969 , stn SLOPE-7 (1 colony) .

Etymology. asymmetro s (Gr.) – without symmetry, referring to the position of the adapical pore.

Diagnosis. Trochosodon with radial series of peristomes, alternating with minute, rounded avicularia. Zooid orifices deeply concealed. Adapical pore asymmetrically placed. Root pores circular.

Description. Colony domed, very small, wider than high; orifices apparently arranged radially; calcification granular. Peristomes raised, tubular, with intervening radial series of minute, rounded avicularia; occasional, asymmetrically placed adapical avicularia; bar without ligula. Primary orifice oval, deeply concealed, with a short, rounded sinus. Adapical pore tubular, present in peripheral and subperipheral zooids, asymmetrically placed inside the margin of the peristome. Ovicells inferred to be asymmetrical. Root pores adapical, circular, with a rim and 1 adjacent avicularium. Antapical surface with occasional short radial series of isolated cancelli, derived from the frontal septular pores of the antapical surface of the zooids.

Colony diameter 2.5 mm, height 1.5 mm, 5 whorls of 8–9 zooids per whorl.

Remarks. T. asymmetricus is the only species among those examined (except T. optatus , see above, and a few zooids of C. stellata ), that exhibits an asymmetrically placed adapical pore. No ovicells have been found but it may be inferred that these, too, would be in an asymmetrical position between the rows of zooid orifices, as are the ovicells of T. optatus Harmer (1957) , together with those of C. striata , C. brevirostris and C. longirostris of Silén (1947), as well as the specimens described by Harmer (1957) assigned to C. catella Canu and Bassler (1929) . The tubular appearance of the adapical pore resembles that figured by Livingstone (1925) in “ C. crassa ”. There are more zooids per whorl than in Trochosodon anomalus but there are several closely similar characters shared by these two species. Both have finely tuberculate calcification and similar radial series of avicularia alternating with the orifices. The primary orifice is also almost identical in appearance (compare Figs 19A , 24F ). However, the adapical pores are completely different in position, so it is inferred that the types of ovicells would be an important distinction between the two taxa. T. asymmetricus occurs from two adjacent stations from the New South Wales slope, from 770 to 1096 m.

Figures

Figure 19. Trochosodon asymmetricus sp.nov. NMV F99011, paratype. A, detail of orifices and asymmetrically placed, tubular adapical pores, scale =100 µm. B, adapical region showing rounded root pores and avicularia, scale = 200 µm. C, detail of marginal peristomes, orifices, adapical pores, and avicularia, scale = 200 µm.

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.