Witchellia hyalina (Buckman, 1924)

Sandoval, José, 2022, Sonniniidae Ammonitina, Middle Jurassic from Southern Spain: taxonomic, biostratigraphical and palaeobiogeographical analysis, Geodiversitas 44 (27), pp. 801-851 : 831

Witchellia hyalina (Buckman, 1924) [M] ( Figs 8C ; 11B ; 13A )

Hyalinites hyalinus Buckman, 1924 : T.A. 5, pl. 519 (HT).

Sonninites simulans – Buckman 1926: T.A. 6, pl. 631. — Chandler & Whicher 2015: pl. 11, fig. 3.

Sonninites aff. simulans – Sandoval 1994: 205, pl. 1, fig. 1.

MATERIAL EXAMINED. — JAC3’.5.8 , JAC3’.5.9 , JAC11.8.21 , JAC11.8.22 , JAC22.47.7 , JAC22.47.8 , JAC22.58.3 , AC 22.58.4 , JAC22.59.7 and JAC22.61.3 .

MEASUREMENTS. — See Table 16.

DESCRIPTION

Planulate evolute shells, with scarcely appreciable uncoiling throughout ontogeny. The umbilicus is relatively wide and shallow. A rectangular compressed whorl section ( Fig. 11B ) has an almost vertically sloping umbilical wall, rounded umbilical edge, almost flat flanks and rounded venter with a well-developed keel. The aperture has sinuous edges and a long ventral prolongation that adjusts to the path of the growth striae. The inner whorls vary depending on the specimen, but generally thickenings are present near the umbilical edge, from which one or two sinuous ribs emerge that weaken in the outer part of the flanks. This ornamentation progressively fades, so that throughout almost the entire last whorl of the PH and in the BC, the ribbing is replaced by growth striae. The septal suture ( Fig. 8C ) is more complex than in other Witchellia species; L, tripartite, is deeper than E, the E-L saddle is wide and high, L-U 2 is narrow, incised and asymmetric, and the umbilical lobes are gently retracted.

REMARKS

The HT of “ Hyalinites ” hyalinus Buckman , from Sherborne, Dorset ( England) is a septate PH of 92 mm in diameter. Subbetic specimens are smaller and slightly more evolute, but coincide in all other characters. Differences in size may be the consequence of the habitat where they lived. For example, a British specimen is from marine offshore with a large amount of aliments, whereas Subbetic forms are from a typical marine basin where, generally, food is scarcer. The differences in the degree of coiling may come from the fact that the Subbetic forms are complete or nearly complete adult specimens, whereas the English forms are PHs, and, as indicated above, little uncoiling of the shells occurs throughout ontogeny. The type of “ Sonninites ” simulans Buckman closely resembles the type of “ H. ” hyalinus , as both forms coincide in coiling, whorl-section, keel, ornamentation in the last preserved whorls, and septal suture. Only minor differences are detected on the innermost whorls, but these are not considered sufficient to separate two species. Furthermore, both HTs are from the same locality and from the same stratigraphic level. Therefore, here, the two forms are considered synonymous.

DISTRIBUTION

The only known specimen figured and nominated as “ Hyalinites ” hyalinus Buckman is the HT that, according to Buckman (1924) comes from the Sauzei of Clatcombe, Sandford Lane, Sherborne, Dorset ( England). The HT of “ Sonninites ” simulans Buckman is also from the Sauzei Zone of Sandford Lane, Sherborne. The specimen figured by Chandler & Whicher (2015), from the Inferior Oolite of Dorset, is from Bj-11 horizon, Propinquans Zone (Patella Subzone). In Morocco, this species occurs in the lower part of the Propinquans Zone ( Sadki 1996). Subbetic specimens are from the Laeviuscula Zone (Laeviuscula Subzone) and the Propinquans Zone (Patella Subzone?) of the Sierra of Alta Coloma (JAC3’, JAC11 and JAC22 sections; Jaén 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. 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.