Conescharellina humerus, 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 : 162-163

Conescharellina humerus sp. nov.

Figures 14B–F

Holotype. NMV P311812 , Miocene, Balcombe Bay , Victoria.

Paratypes. NMV P311813 , P311814 , Miocene , Balcombe Bay .

Other specimens. Miocene, Balcombe Bay (43 colonies); Miocene, Batesford Quarry (170 colonies); Miocene, Muddy Creek (7 colonies); Miocene, Paraatte Bore (8 colonies); Miocene, Puebla Clay, Torquay (16 colonies); Miocene, Mount Schanck, South Australia (approximately 125 colonies).

Etymology. humerus (L.) – a shoulder, with reference to the outline of the lateral avicularia and peristome from antapical view.

Diagnosis. Conescharellina with slightly domed colonies. Zooid orifices radial. Avicularia small, lateral, forming a

“shoulder” visible on marginal peristomes. Round root pore near the centre adapically, surrounded by small avicularia.

Description. Colonies small, slightly domed, distinctly wider than high. Orifices radially arranged towards the margin of the colony. Primary orifices with a distinct, deep, rounded sinus and paired condyles, peristome raised laterally, adapical pore outside peristome. Avicularia small, paired, rounded, lateral and antapical, directed inwardly, bar with ligula, subrostral chamber prominent, visible as a lateral “shoulder” in marginal zooids. A fairly large, rounded root pore near the centre of the adapical region, surrounded by a circlet of six avicularia. Antapical surface cancellate centrally, otherwise smooth, with small avicularia.

Colony diameter 3.3 mm, height 1.5 mm, number of whorls 4, number of zooids per whorl 7.

Remarks. The colonies of C. humerus are widely distributed in the Victorian Tertiary but are not as numerous as those of C. macgillivrayi . C. humerus is immediately recognisable by the profile of the marginal peristomes formed by the prominent lateral avicularian rostra. The rounded root pore with circlet of avicularia is reminiscent of those found in C. eburnea , C. plana , C. perculta and in Crucescharellina australis .

Figures

Figure 14. Conescharellina macgillivrayi sp. nov. and C. humerus sp. nov. A, C. macgillivrayi NMV P311811, antapical view of colony, showing cancelli, scale = 500 _m. B–F. C. humerus, B, NMV P311814, adapical view of colony, showing root pore, scale = 500 µm. C–D. NMV P311812. C, Adapical view of colony, scale = 500 mm. D, detail of orifices and avicularia, scale = 200 µm. E, NMV P311814, detail of root pore (see Figure 14B), scale = 100 µm. F, NMV P311813, detail of marginal zooids, showing profiles of peristomes and avicularia, scale = 100 µm.