Osmolskabole, Lerosey-Aubril & Feist, 2005

Lerosey-Aubril, Rudy & Feist, Raimund, 2005, Ontogeny of a new cyrtosymboline trilobite from the Famennian of Morocco, Acta Palaeontologica Polonica 50 (3), pp. 449-464 : 451

Genus Osmolskabole nov.

Type species: Cyrtosymbole (Waribole) prima Osmólska, 1962 ; Gałęzice , Holy Cross Mountains , Poland, Famennian, Devonian .

Derivation of the name: After professor Halszka Osmólska, Warsaw, in recognition of her fundamental work on cyrtosymboline trilobites.

Assigned species: Cyrtosymbole (Waribole) prima Osmólska, 1962 , Cyrtosymbole (Waribole) secunda Osmólska, 1962 , Cyrtosymbole (Cyrtosymbole) neptis Chlupáč, 1961 .

Diagnosis.— Osmolskabole differs from all other genera of the subfamily by having the following unique combination of characters: glabella low, with strongly tapering and slightly constricted frontal lobe; preglabellar field short; anterior bor− der medially straight and upraised; glabellar furrows faint; palpebral lobes broad (tr.) and far backwardly placed; visual surface very large and gently sloping abaxially, genal spine short; pygidium semielliptical, with slightly inflated border; pygidial axis high with 8–9 rings; postaxial ridge long; post−axial field short or absent; up to 7 pleural ribs, pleural field horizontal adaxially with abaxially impressed pleural and interpleural furrows.

The major traits that distinguish Osmolskabole from Cyrtosymbole , as redefined by Feist and Lerosey−Aubril (2005, this volume), are: glabella (tr. and sag.) low, with strongly tapering frontal lobe and faint glabellar furrows, preglabellar field short, palpebral lobes backwardly placed; eyes comparatively larger (bearing almost twice the number of eye−lenses); inner pleural field horizontal, with adaxially effaced pleural and interpleural furrows, and postaxial ridge conspicuously long.

Osmolskabole share the following features with Pseudowaribole : glabella conical and slightly constricted antero−laterally, palpebral lobes and eyes large, and glabellar, pleural and interpleural furrows frequently effaced. However, it differs from this genus by having the following characteristics: anterior border upraised and straight, vault of glabella higher, dorsal furrows deeper; pygidial border defined.

Remarks.—Previous authors ( Osmólska 1962: 131) were aware of the particularities of the “ neptis – primus –secundus group”( Alberti 1975b) that share some characters with the older Cyrtosymbole , and others with certain species of the younger, late Famennian Cyrtosymbole (Waribole) Richter and Richter, 1926 [= Archegonus (Waribole) sensu Hahn 1965 ; = Pseudowaribole Hahn and Hahn, 1967 ].

After having first assigned this group with doubt to Archegonus (Waribole?) Alberti (1976) reassigned it to Cyrtosymbole . This reflects the hesitation in systematic paleontology when defining a taxon that apparently takes a phylogenetically intermediate position between the older Cyrtosymbole and species of the younger Pseudowaribole . However, we consider that it is adequate to recognize the independant generic status of this group, as it is characterized by a combination of ancestral and derived traits within the evolutionary lineage leading from Cyrtosymbole ( sensu Feist and Lerosey−Aubril 2005 , this volume) to Pseudowaribole .