Peltura sp. A

Ahlberg, Per, Szaniawski, Hubert, Clarkson, Euan N. K. & Bengtson, Stefan, 2005, Phosphatised olenid trilobites and associated fauna from the Upper Cambrian of Västergötland, Sweden, Acta Palaeontologica Polonica 50 (3), pp. 429-440 : 434

Peltura sp. A

Fig. 3H, I .

Material.—One almost complete pygidium, 0.8 mm long (excluding spines) and 1.5 mm wide, and one transitory pygidium, 0.4 mm long (estimated) and 0.9 mm wide.

Remarks.—The larger pygidium ( Fig. 3H ) resembles that of typical Peltura species, but the three pairs of marginal spines are relatively long and directed inwards. The posterior pair of spines is situated quite close to the midline, as in P. acutidens Brögger, 1882 and P. scarabaeoides westergaardi Henningsmoen, 1957 . An ornament of granules is present on the axial rings and on the pleural fields, especially along the anterior edge. Terrace lines are visible on the marginal spines, orientated roughly along the axis of the spines. The transitory pygidium ( Fig. 3I ) has four pairs of marginal spines directed inwards. In this respect it differs from P. scarabaeoides westergaardi , which has three pairs of spines in a transitory pygidium of similar size (see Bird and Clarkson 2003).

Figures

Fig. 3. A. Sphaerophthalmus sp. A, cranidium, SMNH Ar59729 (2.21), sample 2. B. Sphaerophthalmus sp. B, right librigena with intact eye, SMNH Ar59730 (3.11), sample 2. C. Sphaerophthalmus sp. C, incomplete thoracic tergite, SMNH Ar59731 (2.19), sample 2. D–F. Peltura cf. transiens (Brögger, 1882). D. Pygidium, SMNH Ar59732 (1.3), sample 1. E. Pygidium, SMNH Ar59733 (2.7), sample 2. F. Small pygidium, SMNH Ar59734 (3.12), sample 2. G. Peltura cf. paradoxa (Moberg and Möller, 1898), pygidium, SMNH Ar59735 (1.7), sample 1. H, I. Peltura sp. A. H. Pygidium, SMNH Ar59736 (1.2), sample 1. I. Transitory pygidium, SMNH Ar59737 (1.21), sample 1. J. Peltura sp. B, transitory pygidium, SMNH Ar59738 (1.6), sample 1. K–P. Indeterminate olenid fragments. K–M. Occipital rings. K. SMNH Ar59739 (1.19), sample 1. L. SMNH Ar59740 (1.15), sample 1. M. SMNH Ar59741 (2.14), sample 2. N. Axial ring seen edge on, SMNH Ar59742 (1.18), sample 1. O. Axial ring, SMNH Ar59743 (2.22), sample 2. P. Incomplete thoracic tergite, SMNH Ar59744 (1.24), sample 1. Scale bars 0.1 mm.