Hyolithellus filiformis Bengtson, 1990

Wrona, Ryszard, 2004, Cambrian microfossils from glacial erratics of King George Island, Antarctica, Acta Palaeontologica Polonica 49 (1), pp. 13-56 : 48-50

Hyolithellus filiformis Bengtson, 1990 in Bengtson et al. 1990

Fig. 25A–D.

Hyolithellus filiformis Bengtson in Bengtson et al.; Demidenko in

Gravestock et al. 2001: 93, pl. 9: 9, 11 [full synonymy].

Material.—Ten fragmented tubes from erratic boulders Me32, 33, 66. Figured specimens, ZPAL V.VI/32S26; 105S2; 106S5; 110S7.

Description.—Slightly tapering, almost cylindrical phosphatic tubes, usually variably curved, but short fragments can be straight. They are circular in cross−section with diameter 0.1–0.2mm. The outer surface is covered with evenly spaced transverse ribs. This regular annulation can be disturbed, especially in curved fragments. Inner surface of tubes is smooth. Broken tubes show wall structure as a system of several thin layers. Some specimens have tube walls with irregular microborings produced by an enigmatic organism. Opercula closing the tube aperture or any structure for attachment to the substrate have been observed.

Fig. 25. A–D. Hyolithellus filiformis Bengtson. A. Fragment of tube in lateral view, ZPAL V.VI/105S2, erratic Me66. B. Tube opening, in proximal view, Ą showing thickness of tube wall, ZPAL V.VI/106S5, erratic Me33. C. Curved tube, in oblique lateral view, ZPAL V.VI/110S7, erratic Me66. D. Tube in lateral view, ZPAL V.VI/32S6, erratic Me32. E. Tube of Hyolithellus micans (Billings) , ZPAL V.VI/32S4, erratic Me66, in lateral view (E 1), and its enlarged end (E 2). F, G. Torellella sp. F . Steinkern of slightly curved tube in lateral view, ZPAL V.VI/103S13, erratic Me66. G. Steinkern of curved tube in lateral view, ZPAL V.VI/32S11, erratic Me66. H. Lateral view of Byronia? bifida sp. nov. tube, ZPAL V.VI/115S5, erratic Me66. I. Phosphate steinkern of Stapicyathus stapipora (Taylor) archaeocyath cup, ZPAL V.VI/37S1, erratic Me33; in transverse upper (I 1) and oblique longitudinal (I 2) views.

J. Echinoderm stereom, ZPAL V. VI/109 S10, erratic Me66; J 1, phosphatized echinoderm plate; J 2, detail. K–M. Byronia? bifida sp. nov. K. Tube in lateral view, ZPAL V. VI/35 S17, erratic Me66. L. Distal part of holotype tube in lateral view, ZPAL V. VI/39 S8, erratic Me32. M. Distal part of tube in lateral view, ZPAL V. VI/33 S19, erratic Me33. N. Problematic “smooth cone”—steinkern of coeloscleritophoran shell, ZPAL V. VI/35 S8, erratics Me33; in lateral (N 1), anterior (N 2), oblique upper (N 3), and oblique apical (N 4) views .

Remarks.—The Antarctic specimens demonstrate distinctive features closely similar to those of Australian specimens ( Bengtson et al. 1990; Gravestock et al. 2001), whose biological function and significance have been broadly discussed by Bengtson (see Bengtson et al. 1990).

Occurrence.—Early Cambrian (Atdabanian/Botomian) Kulpara Formation, Parara Limestone, and Koolywurtie Limestone Member, Horse Gully, Yorke Peninsula, Stansbury Basin, and Ajax Limestone, Flinders Ranges, Arrowie Basin , South Australia; allochthonous Early Cambrian (Botomian) boulders (Me32, 33, 66), King George Island, Antarctica.