Acuticryphops acuticeps ( Kayser, 1889 )

Feist, Raimund, 2002, Trilobites from the latest Frasnian Kellwasser Crisis in North Africa (Mrirt, central Moroccan Meseta), Acta Palaeontologica Polonica 47 (2), pp. 203-210 : 208

Acuticryphops acuticeps ( Kayser, 1889)

Fig. 4A–D, F, H.

Cryphops acuticeps ( Kayser, 1889) ; Feist and Schindler 1994: 212, pl. 5: 1–11 (see list of older synonymies therein).

Cryphops acuticeps ( Kayser, 1889) ; Feist 1995: 235–239, fig. 11.6.

Cryphops acuticeps ( Kayser, 1889) ; Crônier 1999: 189, figs. 2–8.

Acuticryphops acuticeps (Kayser) ; Crônier and Feist 2000: 505–506, pl. 1: 9.

Material.—Figured specimens: 1 cephalon from locality 1, upper trilobite association ( UM 2− RF 221); 2 cephala from locality 2, upper trilobite association ( UM 2− RF 220, 223); 1 pygidium from locality 2 ( UM 2− RF 222); additional material from section “2”, upper trilobite association: 15 cephala ( UM 2− RF 224–238), 4 pygidia UM 2− RF 239–242); from section “1”, lower trilobite association: 3 cephala ( UM 2− RF 243–245), 2 pygidia ( UM 2− RF 246–247).

Remarks.—The cephalon is characterized by the frontal outline of the glabella, which is strongly protruding adaxially, typically pointed centrally. This feature is less marked in younger specimens. The visual surface of the eyes has an inconstant number of eye−lenses: in the population of Mrirt 2, morphs exhibiting between 1 and 7 lenses co−occur. This feature, and in particular the occurrence of morphs with a single lens, has so far only been observed in Acuticryphops acuticeps populations from Coumiac, southern France. Whereas the populations of cephala are very close to those from Coumiac, both in outline of the glabella and features of the eye−lobe, the pygidia from Mrirt are more flattened dorso−ventrally and are shorter. More material is needed for statistical analyses in order to evaluate the constancy of these features in which case the Moroccan material might represent an independent taxon. Unfortunately, pygidia of Acuticryphops acuticeps from the Rhenish Slate Mountains remain insufficiently known and, in particular, no pygidia have yet been recovered from the type locality Martenberg.