Skryjelites auritus, Valent, Martin, Fatka, Oldřich, Szabad, Michal, Micka, Václav & Marek, Ladislav, 2015

Valent, Martin, Fatka, Oldřich, Szabad, Michal, Micka, Václav & Marek, Ladislav, 2015, Skryjelites auritus gen. et sp. nov. and Quasimolites quasimodo gen. et sp. nov. — two new middle Cambrian hyolithids (? Mollusca) from the Czech Republic, Zootaxa 4007 (3), pp. 419-426 : 422-423

Skryjelites auritus sp. nov.

( Figs. 2 B, C, 3)

1983 Skryjelites auritus sp. nov.; Marek, p. 42–43.

Holotype. NM L40479 ( Figs. 3 C, D); inner surface of operculum.

Paratypes. NM L40721 ( Fig. 3 A); outer surface of operculum. NM L40480 ( Fig. 3 B, E); outer surface of operculum. NM L40725 ( Fig. 3 F); external mould of venter. NM L40720 ( Fig. 3 G); external mould of venter. NM L40724 ( Fig. 3 H); internal mould of conch. NM L40723 ( Fig. 3 I); external mould of dorsum. NM L40722 ( Fig. 3 J); external mould of dorsum. All specimens come from the Buchava locality.

Type horizon and locality. Middle Cambrian, Buchava Formation, Skryje Member, Paradoxides (Eccaparadoxides) pussilus Biozone; Barrandian area, Skryje–Týřovice Basin, Buchava locality, Czech Republic (N 49°56'33.0", E 13°44'41.8").

Material. In addition to the holotype, other 18 opercula, some of them incomplete and 13 fragmented conchs.

Etymology. From the Latin auritus , long-eared, eared.

Diagnosis. The same as for the genus.

Description. Conch orthocone; ventral side very slightly arched; dorsal side vaulted in regular arch. W/h index = 1.4. Angle of divergence reaching about 16 degrees. Lateral edges sharp, sharply rounded on moulds. Conch with orthogonal aperture; ligula attaining length of about two thirds of apertural width. Drop-like paired dorsal apertural muscle scars laterally elongated. Ventral apertural muscle scar indistinct transversally elongated, being broken in a very obtuse angle in its middle. Presence of apical septa could not be proved. Oblong lines of transversally broken traverse riblets developed on the dorsal side of the conch ( Fig. 3 S). Very fine growth-lines developed on ventral side of conch ( Fig. 3 R).

Monoclaviculate operculum. Narrow clavicles showing asymmetrical T-shaped cross-section. Cardinal processes broadly diverging, with their anterior ends opened; distal ends of cardinal processes cone convoluted and accrued to the surface of cardinal area. Conical shield slightly vaulted; cardinal shield plain. Cardinal area bearing distinct, radially arranged and distally tapered teeth. Surface sculpture consisting of fine growth-lines ( Figs. 2 B, 3G).

Dimensions. Maximum length of conch attained about 30 mm.

Occurrence. The type species S. auritus sp. nov. is known only from the middle Cambrian of the Skryje–Týřovice Basin at the Buchava, Hradiště, Dlouhá hora and Luh localities ( Figs. 1 , 2A ).

Figures

FIGURE 3. Skryjelites auritus gen. et sp. nov.; middle Cambrian, Buchava Formation, Skryje Member, Paradoxides (Eccaparadoxides) pusillus Zone, Buchava locality. Scale bar = 1 mm. Skryjelites auritus gen. et sp. nov. A. Paratype, NM L 40721, outer surface of operculum. B. Paratype, NM L 40480, outer surface of operculum. C. Holotype, NM L 40479, inner surface of operculum. D. Holotype, NM L 40479, lateral view of inner surface of operculum. E. Paratype, latex cast of NM L 40480, lateral view of outer surface of operculum. F. Paratype, NM L 40725, external mould of venter with distinct growth lines in apertural region. G. Paratype, NM L 40720, external mould of venter. H. Paratype, NM L 40724, frontal view of internal mould of conch. I. Paratype, NM L 40723, external mould of dorsum with distinct sculpture. J. Paratype, NM L 40722, external mould of dorsum with distinct sculpture.

FIGURE 2. A. Stratigraphic distribution of Skryjelites auritus gen. et sp. nov. and Quasimolites quasimodo gen. et sp. nov. within the Buchava Formation of the Skryje – Týřovice Basin (biostratigraphy after Fatka et al. 2011). 0. Biskoupky. 1. Buchava. 2. Hradiště; 3. Dlouhá hora. Skryje - Luh (southern slope above the Skryjský potok).

FIGURE 1. A, Barrandian area within the Czech Republic. B, Simplified sketch map showing the location of fossil sites in the middle Cambrian Buchava Formation within the Skryje – Týřovice Basin, Central Bohemia (geology modified from Mašek et al. 1997). 1. Buchava locality. 2. Hradiště locality. 3. Dlouhá hora. 4. Skryje - Luh locality (southern slope above the Skryjský potok); the Biskoupky locality is situated about 11 km to the south-west of Čilá.