WITCHELLIINAE, Callomon & Chandler, 2006

Sandoval, José, 2022, Sonniniidae Ammonitina, Middle Jurassic from Southern Spain: taxonomic, biostratigraphical and palaeobiogeographical analysis, Geodiversitas 44 (27), pp. 801-851 : 822

Subfamily WITCHELLIINAE Callomon & Chandler, 2006

Witchelliinae Callomon & Chandler in Chandler, Callomon, King, Jeffreys, Varah & Bentley, 2006: 370.

DESCRIPTION

Medium to relatively large macroconchs [M], but smaller than those of Sonniniinae . Coiling is involute to moderately evolute, with a compressed whorl section, varying from typically rectangular or subtriangular, to even ovate or oxycone, with a more or less developed keel. The ribs, radial or slightly proverse and simple or divided near the umbilical edge, have irregular thickness and usually fade towards the outer whorls, which in some forms become completely smooth or the ornamentation is reduced to striae. The innermost whorls of some forms have small lateral tubercles. The aperture has plain mouth borders. Dimorphic microconchs [m], (until now usually nominated Pelekodites ), small adult at 20-60 mm in diameter, are usually ribbed to the end of the BC and have final adult mouth borders with long, spatulate lappets in some forms. The dimorphic size ratio is modest, between 2:1 and 3:1. The septal suture is simple, with L wide and short; scarcely retracted umbilical lobe, and barely trimmed saddles.

REMARKS

As indicated above, Howarth (2013) included the genera Asthenoceras Buckman, 1899 , Fontannesia Buckman, 1902 , Newmarracarroceras Hall, 1989 , Witchellia Buckman, 1889 , and Guhsania McLearn, 1926 in the subfamily Witchelliinae but placed Dorsetensia in Sonniniinae . However, as also shown above, Asthenoceras and presumably also Fontannesia , Newmarracarroceras , and Latiwitchellia should be transferred to Grammoceratinae , as they coincide in coiling, ribbing, and type of keel as well as presenting an extremely simple septal suture (see Sandoval et al. 2012). Nevertheless, the genus Dorsetensia , which succeeds Witchellia in time, and from which it possibly descended, is included here in Witchelliinae . Witchellia and Dorsetensia have a similar section, similar coiling and ornamentation, and also a comparable dimorphism. The slightly more complex septal suture of Dorsetensia is the only remarkable difference.

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