Witchellia Buckman, 1889

Sandoval, José, 2022, Sonniniidae Ammonitina, Middle Jurassic from Southern Spain: taxonomic, biostratigraphical and palaeobiogeographical analysis, Geodiversitas 44 (27), pp. 801-851 : 823-824

Genus Witchellia Buckman, 1889 [M] & [m]

Witchellia Buckman, 1889: 82 .

Zugophorites Buckman, 1922 [M]: pl. 341. — Type species: Z. zugophorus Buckman, 1922 (OD).

? Stiphromorphites Buckman, 1923 [M]: pl. 398. — Type species: S. nodatipinguis Buckman, 1923 (OD).

Pelekodites Buckman, 1923 [m]: pl. 399. — Type species: P. pelekus Buckman, 1923 (OD).

Hyalinites Buckman, 1924 [M]: pl. 519. — Type species: H. hyalinus Buckman, 1924 OD.

Gelasinites Buckman, 1925 [M]: pl. 593A. — Type species: G. gelasinus Buckman, 1925 (OD).

Rubrileiites Buckman, 1926 [M]: pl. 642. — Type species: R. ruber Buckman, 1926 (OD).

Anolkoleiites Buckman, 1926 [M]: pl. 659. — Type species: A. plenus Buckman, 1926 (OD).

Dundryites Buckman, 1926 [M]: pl. 687. — Type species: D. albidus Buckman, 1926 (OD).

Zugella Buckman, 1927 [M]: pl. 750. — Type species: Z. connata Buckman, 1927 (OD).

Spatulites Buckman, 1928 [m]: pl. 765. — Type species: S. spatians Buckman, 1928 (OD).

Maceratites Buckman, 1928 [m]: pl. 766. — Type species: M. aurifer Buckman, 1928 (OD).

TYPE SPECIES. — Ammonites laeviusculus J. de C. Sowerby, 1824 ( Sowerby 1824: 73, pl. 451, figs 1, 2 [OD]).

DESCRIPTION

The dimorphism in Witchelliinae is consistent and clear. Macroconchs [M], discoidal of medium to relatively large size, are involute to semi-evolute with innermost whorls more evolute than the middle and outer ones, with a subrectangular whorl section, an almost vertical umbilical wall, rounded umbilical margin, and flanks that are flat or very slightly convex. The venter is tabulate, sometimes bisulcate, mainly on inner whorls, rarely tricarinate bisulcate, and the more or less developed keel persists throughout ontogeny. The ribbing has irregular thickness, sinuous, radial or slightly proverse. The ribs, simple or more usually grouped in pairs near the umbilical edge, progressively fade throughout ontogeny, sometimes completely disappearing at the adult stages, when they become smooth or finely striated. Some species can have very small tubercles on inner whorls. The peristome is simple. The septal suture is also simple, with wide and short L, and a few incised saddles. The microconchs [m] (formely Pelekodites , Maceratites and Spatulites ), much smaller and slightly more evolute than macroconchs, are usually ribbed to the BC end (although some forms are striate throughout ontogeny) and have spatulate lateral lappets.

REMARKS

Fernández-López (1985) maintained that the non-tuberculate microconchs, which he included in Maceratites , constitute the dimorphous partner [m] of Witchellia , whereas the tuberculate forms, which he included in Pelekodites , are dimorphic of Sonninia . However, this assertion can not be confirmed because the type species of Pelekodites (see Howarth 2013: fig. 82, 4c-d) is not tuberculate.

Certain problems arise concerning with the taxonomic status of the “genera” Stiphromorphites Buckman, 1923 (Buckman 1923: T.A. 4, pl. 398 (type S. nodatipinguis, OD ) (in the Treatise, synonymous with Euhoploceras) and Dundryites Buckman, 1926 (Buckman 1926: T.A. 6, pl. 687 [type D. albidus, OD ]) (in the Treatise synonymous with Sonninites ), as these forms closely resemble Witchellia [M]. Stiphromorphites nodatipinguis , showing intermediate characters between S. (Euhoploceras) and Witchellia , was included in Witchellia by Parsons (1974: 168) and Fernández-López (1985: 67). However, Dietze et al. (2005: 25) considered it to be synonymous with S. (Euhoploceras) adicra ( Waagen, 1867) whereas Chandler et al. (2006: 363) and Chandler & Whicher (2015: pl. 9, fig. 1) indicated that S. (Euhoploceras) nodatipinguis typifies the horizon Bj8-a, in the Laeviuscula Zone, Trigonalis Subzone in Dorset ( England). Dundryites albidus was included as synonymous with Witchellia by Fernández-López (1985: 81), by Chandler & Whicher (2015) and, with some doubt, by Dietze et al. (2003: 11). However, Dietze et al. (2007: 13) excluded it from the Witchelliinae and revived Buckman’s genus Dundryites . D. albidus is thus possibly the ancestor of Sonninites , displaying intermediate characters between Witchellia and Sonninites .

Witchellia bears considerable affinities with S. ( Sonninia ), S. (Euhoploceras), Dorsetensia , and Sonninites . S. ( Sonninia ) is usually larger, has an ovate or ogival whorl section without a ventral tabulate region, a higher keel, more persistent tubercles, and a more complex septal suture. As indicated above, some “ Pelekodites ” and/or “ Maceratites ”, which are here included as synonymous of Witchellia , may represent S. ( Sonninia ) microconchs [m]. S. (Euhoploceras), which precedes it in time, is larger, generally more evolute, has no grouped ribs, more developed tubercles, and a more complex septal suture. Dorsetensia is similar to Witchellia in size, coiling, whorl section, keel, and dimorphism, but its ribs are single (only exceptionally are grouped), it has no tubercles, and its venter is not tabulate. Meanwhile, Sonninites is larger than Witchellia and generally more involute; also, it has an oxyconic whorl section, roughly rectangular in the middle and outer whorls, which are always striate or smooth, and it has a more complex septal suture.

DISTRIBUTION

Middle Jurassic (Lower Bajocian, Ovale Zone-Propinquans Zone): Europe ( England, Belgium, Luxembourg, France, Germany, Switzerland, Poland, Romania, Bulgaria, Italy, Portugal, Spain), North Africa (Atlas Mountains), Arabian Peninsula, Madagascar, the Caucasus, Iran, Tibet ( China), Japan, western Australia, Canada (British Columbia), United States (Alaska, Oregon), and Argentina. In the Subbetic, Witchellia ranges throughout the Ovale, Laeviuscula, and Propinquans zones, being especially abundant in the Laeviuscula Zone of the central sector of the Median Subbetic, Sierra de Alta Coloma area (Jaén Province).