Palaeozygopleura lukesi, Frýda, Jiří, Ferrová, Lenka & Frýdová, Barbora, 2013

Frýda, Jiří, Ferrová, Lenka & Frýdová, Barbora, 2013, Review of palaeozygopleurid gastropods (Palaeozygopleuridae, Gastropoda) from Devonian strata of the Perunica microplate (Bohemia), with a re-evaluation of their stratigraphic distribution, notes on their ontogeny, and descriptions of new taxa, Zootaxa 3669 (4), pp. 469-489 : 481

Palaeozygopleura lukesi sp. nov.

Fig. 3 A–N

Holotype. UUG JF 922 ( Fig. 3 A–C, H, and I).

Paratypes. The shells figured herein as Figure 3 D (paratype A; UUG JF 923), Figure 3 E,F (paratype B; UUG JF 924), Figure 3 G (paratype C; UUG JF 925), Figure 3 J,M (paratype D; UUG JF 926), Figure 3 K (paratype E; UUG JF 927), Figure 3 L,N (paratype F; UUG JF 928), and 32 unfigured specimens (UUG JF 929–960). All paratypes come from the type locality.

Type locality. Císařský lom quarry, S of the village of Konĕprusy (49°55'00.99"N, 14°3'36.420"E).

Type horizon. Middle part of the Konĕprusy Limestone (Praha Formation), at the same level as Konepruselia zaki Frýda and Ferrová, 2011.

Etymology. After our friend Pavel Lukeš, who has contributed considerably to our understanding of the Devonian stratigraphy of the Barrandian area ( Bohemia).

Diagnosis. Palaeozygopleura with slightly convex sides, convex whorl profile; whorls symmetrically arched, ornamented by prominent, regularly spaced, asymmetrically curved opisthocyrt costae; costae covering lateral as well as basal surface of whorls ( Fig. 3 F); collabral costae culminating slightly above mid-whorl; angle between costae and lower as well as upper suture about 45 degrees; pleural angle of adult shell about 15 degrees; apical angle at first three whorls about 28 degrees; diameter of first half of whorl about 0.27 mm.

Description. High-spired, multiwhorled dextrally coiled shell with up to 10 whorls; sides of shell slightly convex; pleural angle about 15 degrees, sutural slope angle about 17 degrees; lateral whorl sides between sutures very convex and symmetrically arched; sutures relatively deep; base of whorls rounded, anomphalous; lateral, basal parts of whorls ornamented by prominent, asymmetrical arched costae; costae forming wide asymmetrical arched sinus; sinus culminating above middle of whorl; angle between costae, lower as well as upper suture about 45 degrees; distance between costae about double that of costae; protruding protoconch relatively large; diameter of first half of whorl about 0.27 mm, that of embryonic chamber about 0.14 mm; first preserved costae from end of first whorl; preservation of shell not allowing for determination of exact position of protoconch/teleoconch boundary.

Comparison. The deep, asymmetrically arched costae differ P. lukesi from the majority of the species of genus Palaeozygopleura , which have either a straight or symmetrical arched costae. Only three Early Devonian palaeozygopleurid gastropods: P. devonicans , Bojozyga mira , and P. chlupaci Frýda, 1993 , have distinctly asymmetrically arched costae. Shells of P. lukesi have very convex lateral sides of the whorls, in contrast to P. devonicans , where the moderately convex whorls are flattened in their median region (Horný 1955: pl. 1, figs 1, 2). Shells of P. lukesi have a much wider pleural angle than B. mira . In addition, B. mira has less convex whorls, which are rather flat below the upper suture, and a much finer, and less arched costae. The Pragian aged P. lukesi resembles the Lochkovian P. chlupaci by the shape of its costae, but it differs from the latter species by much lower whorls, a wider apical angle, and symmetrically arched whorl side between sutures.

Pathology. An anomalous development of the ornamentation was found on the lateral whorl in one specimen (UUG JF 928: Fig. 3 N), which was most likely caused by shell repair after a failed predation attack. Similarly damaged shells of other species of Palaeozygopleura were described in the Pragian P. a li na e (see Horný 1955: pl. III, fig. 4), in the Lochkovian P. chlupaci (see Frýda 1993: fig. 2.6), and also occur in the Emsian P. vaneki Frýda, Ferrová, Berkyová and Frýdová, 2008 (this study).

Stratigraphic and geographic distributions. Palaeozygopleura lukesi is only known from its type locality and horizon.

Figures

FIGURE 3. Palaeozygopleura lukesi sp. nov. from middle Early Devonian (Pragian) age strata of the Konĕprusy Limestone (Praha Formation) in Barrandian, Czech Republic. A – C, H, and I. Holotype (UUG JF 922), D. Paratype A (UUG JF 923), E, F. Paratype B (UUG JF 924), G. Paratype C (UUG JF 925), J, M. Paratype D (UUG JF 926), K. Paratype E (UUG JF 927), L, N. Paratype F (UUG JF 928). All samples are from the type locality. A— shell width 1.5 mm, shell height: B, C— 4.6 mm, D— 3.9 mm, E, F— 3.8 mm, K— 3.6 mm, L— 5 mm, figure height of shell detail: G— 1.1 mm, H— 1.5 mm, I— 1.6 mm, J— 5.6 mm, M— 2.8 mm, N— 2.1 mm.