Ditomopyginae Hupé, 1953

Fortey, Richard A. & Heward, Alan P., 2015, A new, morphologically diverse Permian trilobite fauna from Oman, Acta Palaeontologica Polonica 60 (1), pp. 201-216 : 204

Subfamily Ditomopyginae Hupé, 1953

Remarks.—Higher level classification of the trilobites described below has been contentious, with some authors placing them in Phillipsiidae (e.g., Owens 2003) and others in Proetidae (e.g., Jell and Adrain 2003). However, a cluster of taxa around Ditomopyge does seem to comprise a compact group, and this subfamily is retained here. Ditomopygine trilobites are divided into at least 17 genera ( Owens 2003) and the characters discriminating them are relatively few, and often a matter of degree rather than “presence or absence”. The group as a whole would benefit from a critical cladistic analysis. Unfortunately, not all the type species are known from complete material. Here we add a few, very well-preserved species which should add clarity to future character coding, which we are mostly placing in previously established genera, basing our assignments particularly on criteria listed in Haas et al. (1980), Owens (1983), and Liebermann (1994). We suggest below a few additional characters that may prove of service as synapomorphies defining phylogenetically-based genera: in Hentigia the reduced genal spines, wedge shaped glabella with short lateral glabellar furrows, and flattened tubercular sculpture; in Iranaspidion , the longitudinally subdivided based of the composite anterior glabellar lobe and spinose genal ridge; in Acanthophillipsia coarse, encrinurid-like tuberculation and uniquely longitudinally divided cephalic border. Permian species hitherto accommodated within Paladin are not considered related to that predominantly Carboniferous Laurentian genus and are the basis of a new genus, Simulopaladin , typified by a pyriform glabella with an occipital ring with three turbercles, and wide, flat cephalic borders. The course of the facial sutures in the described species are all basically similar and the “greek letter” system often used in proetoids is not considered necessary here. However, we remove Triproetus from Ditomopyginae and place it in Proetidae , since it lacks the typical glabellar structure of ditomopygines and has a short pygidium with few segments.

All the species described below are known with certainty only from the type locality.