Witchellia companyi, Sandoval, 2022

Sandoval, José, 2022, Sonniniidae Ammonitina, Middle Jurassic from Southern Spain: taxonomic, biostratigraphical and palaeobiogeographical analysis, Geodiversitas 44 (27), pp. 801-851 : 834-835

Witchellia companyi n. sp. [M]

( Figs 8 D-E; 11C; 13D-F)

urn:lsid:zoobank.org:act:A30DAB70-2DED-4484-8755-90D94C4825A5

DIAGNOSIS. — Macroconch planulate and evolute with wide and shallow umbilicus, rectangular compressed section, fine keel, ribbing varying throughout ontogeny with the BC end becoming smooth or finely striate, very simple septal suture.

TYPE MATERIAL. — Holotype: Specimen JAC11.8.16 (HT), Department of Stratigraphy and Palaeontology, Faculty of Sciences, University of Granada ( Spain) . — Paratypes: specimens JAC11.8.14 , JAC11.8.15 , JAC11.8.17 , JAC11.8.18 , and JAC11.8.19 ( PT).

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

DERIVATION OF NAME. — In honour of my colleague Miguel Company, professor of Palaeontology at the University of Granada, Spain.

MATERIAL EXAMINED. — JAC11.8.14 , JAC11.8.15 , JAC11.8.16 , JAC11.8.17 , JAC11.8.18 , JAC11.8.19 , JAC11.8.23 , JAC11.8.31 , JAC22.54.6 and JAC22.54.7 .

MEASUREMENTS. — See Table 19.

DESCRIPTION

Medium-sized planulate macroconchs, evolute (U/D varying between 0.39 and 0.42 in complete adult specimens) with moderate whorl expansion and a relatively wide and shallow umbilicus. The whorl section ( Fig. 11C ) is almost rectangular, with flat and inclined (at times almost vertical) umbilical wall, a rounded umbilical edge, flattened flanks, and a narrow, tabulated ventral region, with a thin and relatively high keel lacking lateral grooves. It has a simple opening with little ventral expansion. The ornamentation is reminiscent of that of W. romanoides . The innermost whorls are not detectable in any of the available specimens and have no tuberculate stage. The inner and intermediate whorls present weak flexuous, subradial ribs, strongly projecting forward in the ventral region, which during ontogenetic development are usually successively simple, divided, fasciculate, grouped at the umbilical border, and again simple. The outer whorls may become almost smooth, with flexuous growth striae arranged in bundles. The septal suture ( Fig. 8 D-E) is relatively simple; E is as deep as L, the saddle E-L is wide and strongly asymmetrical, L is tripartite, L-U 2 is narrow and high, and the umbilical lobes are slightly retracted.

REMARKS

The most similar species are W. romanoides ( Douvillé, 1885) and W. pseudoromanoides Dietze, Chandler & Schweigert 2003 , but both are more involute and the former is also usually less ornamented whereas the latter is more strongly ribbed and has a broader whorl expansion. W. companyi n. sp. could possibly be a direct descendant of latest W. romanoides .

DISTRIBUTION

Lower Bajocian, Laeviuscula Zone (Laeviuscula Subzone)– Propinquans Zone (Patella Subzone). The species has been recorded only in the Sierra de Alta Coloma area ( Granada and Jaén Provinces).

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.