Poloniproductus BIERNAT et LAZAREV, 1988

Mergl, Michal & Budil, Petr, 2019, Rhynchonelliform Brachiopods And Trilobites Of The ‘ Upper Dark Interval’ In The Koněprusy Area Devonian, Eifelian, Kačák Event; The Czech Republic, Fossil Imprint 75 (1), pp. 92-107 : 96-97

Genus Poloniproductus BIERNAT et LAZAREV, 1988

T y p e s p e c i e s. Productella varians BIERNAT, 1966 ;

Skały Beds, Eifelian; Poland.

Poloniproductus varians ( BIERNAT 1966) Pl. 1, Figs 6–11

1896 Productella subaculeata var. angustior ; Gürich, p. 217.

1896 Productella subaculeata var. latior ; Gürich, p. 218.

1966 Productella varians n. sp.; Biernat, pp. 66–77, text-figs 19–21, pl. 11, figs 1–23, pl. 12, figs 1–16, pl. 13, figs 1–10.

1988 Poloniproductus varians ( BIERNAT, 1966) ; Biernat and Lazarev, pp. 67–68, text-fig. 2, pl. 17, figs 1–5, pl. 17, figs 1–5, pl. 18, figs 1–4, pl. 19, figs 1–3, pl. 20, figs 1, 2.

2009 Poloniproductus varians ( BIERNAT, 1966) ; Halamski, pp. 67, 68.

2013 Poloniproductus varians ( BIERNAT, 1966) ; Halamski and Baliński, p. 253, fig. 5. [for complete synonymy see Halamski (2009) and Halamski and Baliński (2013)]

M a t e r i a l. Three ventral valves ( PCZCU 2266 , PCZCU 2268 , PCZCU 2269 a), two dorsal valves ( PCZCU 2267 , PCZCU 2294 ) and one juvenile dorsal valve ( PCZCU 2270 ) .

D e s c r i p t i o n. The shell is deeply concavo-convex, with a thin-walled dorsal valve and much thicker ventral valve. The outline is transversely ovate. The largest entire shell is 8.5 mm wide and 6.0 mm long but fragments indicate slightly larger shell size.

The dorsal valve is deeply concave, with maximum concavity anteriorly, having flattened corners and a weakly concave posteroaxial part of the shell. The cardinal extremities are subrectangular, the maximum width lies at the posterior one-third. The interior is unknown except for the presence of fine endospines. Ornamentation of the dorsal valve consists of fine concentric growth lines arranged ca. 0.1 mm apart having a somewhat wavy course. These lines change to coarse rugellae near the hinge line. Shallow imperfectly bordered large pits covering the dorsal surface have the same spacing as the spines on the opposite (ventral) valve.

The ventral valve is highly convex in transverse and axial profiles, with flattened posterolateral corners. The beak is prominent, with asymmetric cicatrix, shortly overturned above the hinge lines. The interior has densely evenly spaced pustules. Ornamentation of the ventral valve consists of evenly spaced fairly coarse thick-walled suberect spines. Proximal parts of the spines are distinctly curved. The entire spine length is unknown. Concentric ornamentation consists of fine growth lines having a wavy course around the base of the spines. Lines closer to the hinge lines are coarser, forming short rugellae. Radial ornamentation is absent.

R e m a r k s. The disarticulated valves found in the UDI of the Srbsko Formation clearly resemble externally those of Poloniproductus varians ( BIERNAT, 1966) which is an abundant productid of the Skały Beds of the Holy Cross Mountains ( Biernat 1966, Biernat and Lazarev 1988). The only difference is the smaller size of specimens from the UDI, but they most likely represent immature individuals.

O c c u r r e n c e. UDI, samples TM 10, TM 11, TM 12; outside Bohemia, the species is known from the Upper Eifelian (Skały Beds) to Lower Givetian of the Łysogóry region of the Holy Cross Mountains, Poland ( Biernat and Lazarev 1988, Halamski 2009), and from the Upper Eifelian to Lower Givetian of eastern Anti-Atlas, Morocco ( Halamski and Baliński 2013).