Trimerocephalus (Trifoliops), 2003

Crônier, Catherine, 2003, Systematic relationships of the blind phacopine trilobite Trimerocephalus, with a new species from Causses-et-Veyran, Montagne Noire, Acta Palaeontologica Polonica 48 (1), pp. 55-70 : 56-58

Subgenus Trimerocephalus (Trifoliops) subgen. nov. Fig. 2A–D.

Type species: Trimerocephalus (Trifoliops) trifolius ( Osmólska, 1958) ; Upper Devonian (Famennian); Holy Cross Mts., Poland .

Derivation of the name: After the clover−shaped cephalic outline; subgenus being distinguished from other species representative of genus

CRÔNIER—PHYLOGENY OF PHACOPINE TRILOBITE TRIMEROCEPHALUS 57

A 3 A1 A 2 B3 B1 B2 B4 C1 C3 C4 D1 D2 C2 C5 D 3

Trimerocephalus by a clover−shaped cephalic outline: the frontal border widens distally close to antero−lateral angles.

Diagnosis.—Subgenus of Trimerocephalus McCoy exhibiting the following characteristics: clover−shaped cephalic outline; subpentagonal glabella with parabolic frontal outline; S1 continuous; facial suture cutting the cheeks. Vincular furrow very broad (tr.) and deep with an angular curve; posterior band of the cephalic doublure narrow (sag.). Dense and fine granulation. Pygidium with a posterior margin strongly widened transversally.

Species included.— Trimerocephalus (Trifoliops) trifolius ( Osmólska, 1958) subgen. nov. and Trimerocephalus (Trifoliops) nigritus subgen. et sp. nov.