Witchellia albida (Buckman, 1926)

Sandoval, José, 2022, Sonniniidae Ammonitina, Middle Jurassic from Southern Spain: taxonomic, biostratigraphical and palaeobiogeographical analysis, Geodiversitas 44 (27), pp. 801-851 : 828

Witchellia albida (Buckman, 1926) [M]

( Figs 8B ; 11A ; 12 A-D)

Dundryites albidus Buckman, 1926 : T.A. 6, pl. 687 (HT); 1926: T.A. 7, p. 12.

Witchellia albida – Fernández-López 1985: 81, text-figs 8D, 8E, pl. 5, fig. 6, pl. 6, fig. 3. — Chandler & Whicher 2015: pl. 19, figs 2, 3.

Dundryites aff. albidus [M] – Dietze et al. 2007: 6, pl. 3, fig. 1.

Dundryites albidus [M] – Dietze et al. 2007: 6, pl. 3, fig. 2.

MATERIAL EXAMINED. — JAC11.7.5 , JAC13. R.3 , JAC13. R.34 , JAC22.30.1 , JAC22.32.5 , JAC22.35.3 , JAC22.35.5 , JAC22.42.7 , JAC22.42.8 , JAC22.43.14 , JAC22.43.15 , JAC22.43.16 , JAC22.43.17 , JAC22.43.18 , JAC22.44.9 , JAC22.44.10 , JAC22.44.11 , JAC22. R.3 , JAC22. R.6 and JFA. R.1.

MEASUREMENTS. — See Table 14.

DESCRIPTION

Medium-sized relatively involute macroconchs with medium (U/D varying between 0.23 and 0.30) and shallow umbilicus. The whorl section ( Fig. 11A ) is subrectangular with a subvertical umbilical wall, rounded umbilical edge, almost flat flanks and tabulate ventral area with a high keel. The innermost whorls are not preserved. In the inner whorls, the ribs, some of which arise divided from a small thickening near the umbilical edge, are moderately falcate. Later the ribbing is irregular with a thick rib, which can bifurcate at mid-flank height and is followed by secondary ribbing that is well marked only in the upper part of the flanks where the ribs bend strongly forward. Finally, the ribbing becomes wide and spaced and tends to fade at the BC end. The septal suture, preserved in the specimen JAC22.R.3 ( Fig. 8B ), is complex; L is tripartite, strongly asymmetrical and incised, and the L-U 2 saddle is narrow at the base and incised above.

REMARKS

The Subbetic forms described above are quite similar to the HT of W. albida (Buckman, 1926) , but some are slightly more evolute and have more persistent ribbing.Considering the morphology of the septal suture, Dietze et al. (2007: 13) excluded W.albida from the Witchelliinae , restoring the genus Dundryites Buckman. According to these authors, “ D. ” albidus Buckman shows intermediate characters between Witchellia and Sonninites .

DISTRIBUTION

According to Buckman (1926), the HT of W. albida is from the Mollis horizon. Callomon & Chandler (1990: 97) cited it from the Trigonalis Subzone (Bj-8). According to Chandler et al. (2006: fig. 2), the type is from the Bj-5 horizon (Ovale Zone), but in the type locality the species is also present in the Laeviuscula Zone and Subzone(Bj-10a horizon).At Little Down Wood (Dundry Hill, Somerset, England), this species occurs in the Ovale Zone associated with W. romanoides ( Douvillé, 1885) , W. patefactor (Buckman, 1923) , W. pavimentaria (Buckman, 1927) , W. connata (Buckman, 1927) , W. cf. jugifera ( Waagen, 1867), W. cf. zugophora (Buckman, 1922) , and Fissilobiceras fissilobatum ( Waagen, 1867) , among others, but specimens resembling ‘ Dundryites’ albidus range upwards into the Laeviuscula Zone ( Dietze et al. 2007: 5-7). Chandler et al. (2014) cited W. albida in the Laeviuscula Zone (Trigonalis Subzone, Bj-8b horizon) from Frogden Quarry, Oborne, Dorset ( England). The specimen figured by Chandler & Whicher (2015) is from the base of the Laeviuscula Zone (Sayni Subzone). In the Iberian range ( Spain), the species is common in the Ovale Zone, but it is probably present also in the lower part of the Laeviuscula Zone (Fernández-López 1985: 82). The Subbetic specimens are found in the Laeviuscula Zone (Trigonalis and probably Laeviuscula subzones) of Sierra de Alta Coloma area (Jaén Province) and Rio Fardes area (Granada Province).

Figures

FIG. 8. — Septal suture of some Subbetic sonniniids: A, Sonninia (Euhoploceras) cf. polyacantha (Waagen, 1867) [M], specimen JAQ1.3.1; B, Witchellia albida (Buckman, 1926) [M], specimen JAC13.R.3; C, Witchellia hyalina (Buckman, 1924) [M], specimen JAC11.8.21; D, E, Witchellia companyi n. sp. [M], specimens JAC11.8.22 and JAC11.8.16 (HT); F, Dorsetensia liostraca Buckman, 1892 [M], specimen JGa8.32.4. Scale bars: 5 mm.

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. 12. — A-D, Witchellia albida(Buckman, 1926) [M]: A, JAC11.7.5,Laeviuscula Zone,Sierra de Alta Coloma (JAC11 section); B, JAC22.35.5,Laeviuscula Zone, Trigonalis Subzone,Sierra de Alta Coloma (JAC22 section); C, JAC13.R.3,Laeviuscula Zone?, Sierra de Alta Coloma (JAC13 section); D, JAC22.R.3, Laeviuscula Zone?, Sierra de Alta Coloma (JAC22 section). E-G, Witchellia rubra (Buckman, 1926) [M]: E, JAC3.71.4, Laeviuscula Subzone, Sierra de Alta Coloma (JAC3 section); F, JAC22.R.8, Laeviuscula Zone?, Sierra de Alta Coloma (JAC11 section); G, JAC3’.4.11, Propinquans Zone, Patella Subzone, Sierra de Alta Coloma (JAC3’ section). Scale bar: 1 cm.