Kowalatrochus sanctacrucensis, Krawczyński, 2002

Krawczyński, Wojciech, 2002, Frasnian gastropod synecology and bio-events in the Dyminy reef complex of the Holy Cross Mountains, Poland, Acta Palaeontologica Polonica 47 (2), pp. 267-288 : 276-278

Kowalatrochus sanctacrucensis sp. nov.

Fig. 8A–K .

Holotype: GIUS 4−1569 /Ko−81 ( Fig. 8A ).

Type horizon and locality: As for the genus.

Derivation of name: From Latin name of the Holy Cross Mountains.

Material.—Thirtytwoalmostcompletelypreservedshellsand about 60 fragments with well preserved ornamentation (ZPAL Ga−VI/49–55, 57–59; GIUS 4−1017/Gr−149, 4−1019–1020/ Gr−151–152, 4−1022–1028/Gr−154–160, 4−1030–1034/ Gr−162–166, 4−1045/Gr−177/2, 4−1115/Jaź−10, 4−1119–1128/ Jaź−14–23, 4−1213–1214/SKo−9–10, 4−1217–1227/Ko−4–14, 4−1257–1258/Ko−44–45, 4−1336/Ko−58, 4−1348/Ko−70/8, 4−1351–1352/Ko−73–74).

Diagnosis.—Ornamentation consists of nine spiral cords on the whorl ramp and 10–11 spiral cords below the periphery onthebase.Widecollabralundulationsarealsovisibleonthe ramp.

Description.—Large−sized shell (to 5 cm of height), trochiform with 7–8 whorls and thick walls of the spire. The height of the spire is a little larger than the height of the aperture. The ramps of the whorl are relatively sleeply sloping and weakly arched. A small callus is present on the cryptomphalous base. Small funicles surround the umbilicus. Sutures shallow, poorly demarcated. Aperture rounded, outer lip narrow along its edges. Protoconch is unknown. Pleural angle is stable (55–65°). Growth lines prosoclinal on the ramp and base. Ornamentation is mainly spiral: 9 spiral cords and 13–14 wide collabral undulations on the ramp of the whorl; the ninth spiral cord forms a prominent periphery; two strong spiral cords just below periphery, and the next 8–9 cords are weak. All spiral cords flattened and intersected by growth lines.

Variability.—The shells of Kowalatrochus sanctacrucensis show moderate differences of the translation index H/W (1.15–1.65) and the index of apertural shape Ha / Wa (1.1–1.5) ( Fig. 11 ).

Distribution.—Holy Cross Mountains: Kowala, set A 2, Jaźwica, set I–K, and?Sitkówka−Kowala, set B (the upper Sitkówka Beds; early Frasnian); Grabina, set A (the upper Sitkówka Beds; middle Frasnian).

Figures

Fig. 8. Kowalatrochus sanctacrucensis association from the early and middle Frasnian of the upper Sitkówka Beds. A–J. Kowalatrochus sanctacrucensis gen. et sp. nov. A. Apertural view of shell, holotype GIUS 4−1569/Ko−81, × 2. B, C, E–G, I. Apertural and lateral views of shell with well preserved ornamentation. B, C. ZPAL Ga−VI/59. E. GIUS 4−1217/Ko−4. F. GIUS 4−1223/Ko−10. G. GIUS 4−1219/Ko−6. I. ZPAL Ga−VI/58. B, C, E–G. Natural size. I. × 1.5. D, J. Shells with poorly preserved last whorl, Jaźwica, set I, natural size. D. GIUS 4−1127/Jaź−22. J. GIUS 4−1120/Jaź−15. H. Shell with poorly preserved ornamentation, Grabina, set A, GIUS 4−1019/Gr−151, × 1.7. K. Kowalatrochus cf. sanctacrucensis gen. et sp. nov., lateral views, Sitkówka−Kowala, set B, GIUS 4−1214/SKo−10, × 2. L, M. Westerna subcostata (Schlotheim, 1820) comb. nov., Sitkówka−Kowala, set B, GIUS 4−851/SKo−6, natural size. L. Apertural view with well preserved ornamentation. M. Lateral view with shown palatal folds on internal mould. N. Coelozone sp., lateral view with wide selenizone, GIUS 4−1237/Ko−24, × 5. O. Naticopsis (Naticopsis) inflata (Roemer, 1843), apertural view of juvenile shell, GIUS 4−1238/Ko−25, × 6. P. Naticopsis (Naticopsis) protogaea (Goldfuss, 1844), lateral view of poorly preserved shell, GIUS 4−1353/Ko−75, × 2. A–C, E–G, I, N–P. Kowala, set A2.

Fig.11.Distributionoftranslation(H/W)andofaperturalshape(Ha/Wa)indexesof Kowalatrochus sanctacrucensis gen.etsp.nov.fromtheearlytomiddle Frasnian of the upper Sitkówka Beds.