Witchellia striata, Sandoval, 2022

Sandoval, José, 2022, Sonniniidae Ammonitina, Middle Jurassic from Southern Spain: taxonomic, biostratigraphical and palaeobiogeographical analysis, Geodiversitas 44 (27), pp. 801-851 : 835-836

Witchellia striata n. sp. [M]

( Figs 11D ; 13 G-H)

urn:lsid:zoobank.org:act:565D9D7B-5E38-4DA9-82A3-74C76491E98B

Witchellia rubra – Sandoval 1990: 146, pl. 1, fig.7, non Buckman, 1926.

DIAGNOSIS. — Macroconch, planulate, relatively involute with shallow umbilicus, compressed rectangular section with a very shallow depression in the lower part of the flanks, tabulate venter with a relatively high hollow keel. Weak falcate ribbing that progressively fades, being replaced by bundles of striae. The septal suture is simple.

TYPE MATERIAL. — Holotype: specimen JAC11.4.27, held in the Department of Stratigraphy and Palaeontology , Faculty of Sciences, University of Granada ( Spain).

TYPE LOCALITY AND OCCURRENCE. — Sierra Alta Coloma (JAC11 section; Jaén Province), central sector of the Median Subbetic, Betic Cordillera , S Spain, Lower Bajocian (Laeviuscula Zone, Trigonalis Subzone) .

DERIVATION OF NAME. — Ornamentation composed mainly of striae.

MATERIAL EXAMINED. — Two specimens: JAC4.36.1, JAC11.4.27 ( HT).

MEASUREMENTS. — See Table 20.

DESCRIPTION

Planulate semi-involute, medium-sized shells, with appreciable uncoiling throughout ontogeny and with medium-wide, shallow umbilicus. An almost rectangular compressed whorl section ( Fig. 11D ), which has a vertical umbilical wall, an abrupt umbilical edge at right angles, and almost flat flanks with a very shallow depression (barely noticeable) in its lower part. The venter is clearly tabulate with a high hollow keel. The aperture is not well preserved, although the holotype is almost complete and appears to be adult. The inner and middle whorls support fine falcate ribs, which are single or divided into the inner third of the flanks. The weak and poorly marked secondaries strongly project forward along the ventrolateral edge. From the last part of the PH, ribbing progressively weakens, being replaced by bundles of striae or by very faint ribs in the BC. The septal suture, typical of Witchellia , has short lobes and low saddles.

REMARKS

These Subbetic forms are quite similar to the HT of W. hyalina but are slightly more involute, have less marked ribs on inner whorls, falcate rather than sinuous ornamentation, and bear striae that form bundles in the BC. Moreover, the new species appears to be chronostratigraphically earlier. W. romanoides is more evolute, has any depression in the lower part of the flank and has more pronounced and less striate ornamentation.

DISTRIBUTION

Laeviuscula Zone, Trigonalis Subzone; Sierra de Alta Coloma (sections JAC4 and JAC11; Jaén Province).

Figures

FIG. 11. — Cross-sections of some species of Witchellia: A, Witchellia albida (Buckman) [M], specimen JAC22.R.3; B, Witchellia hyalina (Buckman) [M], specimen JAC11.8.21; C, Witchellia companyi n. sp. [M], specimen JAC11.8.16 (HT); D, Witchellia striata n. sp. [M], specimen JAC11.4.27 (HT). Scale bars: 5 mm.

FIG. 13. — A, Witchellia hyalina (Buckman, 1924) [M], JAC11.8.21, Propinquans Zone,Patella Subzone, Sierra de Alta Coloma (JAC11 section); B, Witchellia sayni Haug, 1893 [M], JAC11.(4-7).1, Laeviuscula Zone?, Sierra de Alta Coloma (JAC11 section); C, Witchellia laeviuscula (J. de C. Sowerby, 1824) [M], JAC3.71.2, Laeviuscula Subzone, Sierra de Alta Coloma (JAC3 section); D-F, Witchellia companyi n. sp. [M], JAC11.8.16 (HT), JAC11.8.22, JAC11.8.14, Propinquans Zone, Patella Subzone, Sierra de Alta Coloma (JAC11 section); G, H, Witchellia striata n. sp. [M]; G, JAC11.4.27 (HT), Laeviuscula Zone, Trigonalis Subzone, Sierra de Alta Coloma (JAC11 section); H, JAC4.36.1, Laeviuscula Zone, Sierra de Alta Coloma (JAC4 section). Scale bar: 1 cm.