Pechoralepis, Valiukevičius & Burrow, 2005

Valiukevičius, Juozas & Burrow, Carole J., 2005, Diversity of tissues in acanthodians with Nostolepis-type histological structure, Acta Palaeontologica Polonica 50 (3), pp. 635-649 : 645

Genus Pechoralepis nov.

Comment.—The new genus Pechoralepis is erected for the former Nostolepis spp. of the fourth structural group.

Derivation of the name: From the Pechora Plate, the region of origin of the type species, and from the Greek lepis, scale.

Type species: Pechoralepis zinaidae ( Valiukevičius, 2003b) ; Timan−Pechora region , Kozhym River , outcrop 236, samples 16–42; Lower Devonian , Lochkovian, Ovinparma Formation, members 1–2 .

Age and geographic distribution: Upper Silurian, Pridoli, Greben’ Regional Stage and Lower Devonian, Lochkovian, Ovinparma and Sotchemkyrt regional stages. Timan−Pechora region ( Russia).

Species included: Type species and Pechoralepis adzvensis ( Valiukevičius, 2003b) , and P. valentinae ( Valiukevičius, 2003b) .

Diagnosis.—Acritolepid acanthodians having prepectoral pinnal plate with oblique rows of tubercles and pectoral spines with a wide leading edge ridge and one pair of lateral ribs; ventral (prepelvic) spines with a wide leading edge ridge and two pairs of longitudinal lateral ribs; head tesserae crowned by semiconcentric or stellate platelets with areal growth zones; rhomboidal to ellipsoidal trunk scales with inclined radial or subradial robust, rounded ridges converging into long medial ridges enclosing a raised central area, with one or two pairs of oblique symmetric neck ridges pointed posteriorly; stranggewebe with long and dense oriented lacunae only developed in a restricted area of the posterior crown; highly odontocytic mesodentine in the anterior part of the crown.

Discussion.—The prepectoral spines of Pechoralepis gen. nov. differ from those of Acritolepis in their sculpture. The ridgeness on scale crowns resembles that of Vesperalia or Nostolepis , but Pechoralepis differs in having the clear oblique neck ridges converging with those of the posteromedian crown and the best developed medial area on scale crown. The type and combination of stranggewebe and odontocytic mesodentine in the crown differ to that of other taxa.