Hadimopanella apicata Wrona, 1982

Wrona, Ryszard, 2004, Cambrian microfossils from glacial erratics of King George Island, Antarctica, Acta Palaeontologica Polonica 49 (1), pp. 13-56 : 42

Hadimopanella apicata Wrona, 1982

Fig. 18E, F.

cf. Hadimopanella apicata Wrona ; Müller and Hinz−Schallreuter 1993: 584, fig. 16G, H [full synonymy].

Material.— Four isolated sclerites from erratic boulders Me33 and 66. Figured specimens, ZPAL V. VI/24 S20, 36 .

Description.—These small discoidal phosphatic sclerites (diameter 47–84 µm, mode 58 µm) consist of two layers (Fig. 18E, F). The lower layer forms an expanded base, with smooth and flat or slightly convex to concave surface. The upper layer forms the crown (cap), bearing one node. The nodes are usually 10 µm in diameter and 15 µm high. These specimens usually have a fine corrugation on the margin of nodular surfaces. The crown sometimes does not cover the base; in such cases the suture between the outer and inner layers is displayed, revealing a striated basal margin (Fig. 18F 1) in a characteristic radiating pattern. The elevation of the upper surface ranges from about 25–35 µm.

Remarks.—The Antarctic specimens differ slightly in their generally smaller size compared to Spitsbergen type specimens from the Lower Cambrian of the Hornsund region ( Wrona 1982). They are reminiscent of H. apicata specimens found in the Lower Cambrian of Comley, Shropshire, England ( Hinz 1987: pl. 4: 3, 6), as well as of the subcircular plate with a strongly developed, tall central cone identified as Palaeoscolecida genus indeterminate cf. H. apicata ( Müller and Hinz−Schallreuter 1993) . The ornamentation can also be compared with the much smaller platelets occurring in many articulated cuticles of various palaeoscolecid genera.

Occurrence.—Allochthonous Early Cambrian (Botomian) boulders (Me33 and 66), King George Island, Antarctica.