Balnibarbi erugata sombrero ( Fortey, 1974 )

Hopkins, Melanie J., 2019, Phylogenetic analysis and revision of the trilobite subfamily Balnibarbiinae (Olenidae), American Museum Novitates 2019 (3928), pp. 1-1 : 1-

Balnibarbi erugata sombrero ( Fortey, 1974)

Figure 2F

Balnibarbi sombrero Fortey, 1974: 32 , pl. 6, fig. 1-4.

HOLOTYPE: Cranidium, PMO NF 835 (figured in Fortey, 1974: pl. 6, fig. 1-2).

TYPE LOCALITY: Profilstranda, Olenidsletta Member, Valhallfonna Formation, Ny Friesland, Spitsbergen, Svalbard.

STRATIGRAPHIC RANGE: Middle of trilobite zone V 1b ( Fortey, 1980). This zone coincides with the lower Oepikodus evae conodont zone and Pendeograptus fruticosus graptolite zone within the upper Floian (fig. 1; see also Kröger et al., 2017).

DIAGNOSIS: Balnibarbi erugata species with relatively long (sag.) preglabellar field (>0.35 length of glabella) and smooth exoskeletal surface. Known only from cranidia.

Figures

FIGURE 2. Balnibarbi erugata Fortey, 1974, close-ups. A. Balnibarbi erugata erugata, holotype cranidium, PMO-NF-3016. Note exfoliation of frontal area and glabella. Arrow points to terrace lines on anterior border that are expressed on both the external surface and internal mold. B. Anterior border of Balnibarbi erugata erugata, CAMSM F3976, showing faint caeca and very fine granulation on frontal area near anterior border furrow and terrace lines on border. C. Posterior border furrow on Balnibarbi erugata erugata, CAMSM F3976, showing very fine granulation. D. Occipital ring of Balnibarbi erugata erugata, PMO-NF-695, showing very fine granulation on glabella. E. Balnibarbi erugata erugata PMO-NF-772. Arrows point to select pits in anterior border furrow; specimen is exfoliated. F. Balnibarbi erugata sombrero, PMO-NF-2054. Arrows point to select pits in anterior border furrow on exfoliated surface. Scale bars = 1 mm.