Dorsetensia pinguis
Creators: name: Sandoval, José
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Cephalopoda
Ammonoidea
Sonniniidae
Dorsetensia
Dorsetensia pinguis

description: Dorsetensia pinguis (Roemer, 1836) [m] & [M?] (Fig. 14 V-X)
Ammonites pinguis Roemer, 1836: 186, pl. 12, fig. 3 (HT).
Sonninia (Poecilomorphus) pinguis pinguis – Huf 1968: 54, pl. 4, figs 7(HT refigured) to fig. 12, pl. 5, figs 1-8.
Dorsetensia pinguis – Morton 1972: 510, pl. 105, figs 1-10, 17-20. — Schlegelmilch 1985: 65, pl. 19, fig. 10 (HT refigured).
Nannina pinguis – Fernández-López 1985: 115, pl. 10, fig. 8.
Dorsetensia (Nannia) pinguis (m) – Metz 1990: 10, pl. 4, fig. 3.
Dorsetensia pinguis pinguis – Ohmert et al. 1995: 52, pl. 1, figs 1-3.
? Sonninia sp. [corresponds to Dorsetensia pinguis auct.] – Dietze et al. 2008: 148, figs 4e, g.
MATERIAL EXAMINED. — JAC3.110.1, JAC3’.22.6, JAC3’.22.12, JAC3’.22.18, JAC3’.22.26, JAC3’.22.28, JAC3’.22.31, JAC3’.22.35, JAC3’.22.36, JAC3’.22.39, JAC3’.22.45, JAC3’.22.48, JAC11. R.68, JAQ 1.70.4, JAQ 1.71.4 and JAQ 1.71.5.
MEASUREMENTS. — See Table 29.
DESCRIPTION
The HT (refigured by Huf 1968 and by Schlegelmilch 1985) is a small septate specimen showing only juvenile stages, with relatively evolute coiling and a barely compressed subquadrangular whorl section.The Subbetic specimens are relatively small, moderately evolute (O/D varying from 0.23 to 0.34 on last preserved whorl), with inner whorls somewhat more evolute than the outer ones. The whorl section is barely compressed, although this is difficult to verify due to the lateral crushing of the specimens. The umbilical wall is steep with a rounded umbilical edge and barely convex flanks while the venter is broad, tabulate with a prominent keel without grooves. The innermost whorls can be smooth, but later broad, simple or bifurcating ribs appear at the umbilical edge and fade on the top of the flanks before reaching the venter. The ribs are slightly flexed on the whorl sides and ventrally project forward. In some specimens, the ribs progressively erase on the outer whorls and the BC end becomes almost smooth. The crushing of the Subbetic specimens makes it difficult to differentiate all the taxonomic characters, but a specific diversity similar to those shown by Huf (1968) or Morton (1972) can be discerned, although most of the Subbetic specimens are smaller. The septal suture cannot be well observed in any of our specimens.
REMARKS
The differences with D. hannoverana (Hiltermann, 1939) are minimal, but the innermost whorls of D. pinguis can be almost smooth whereas they are strongly ornamented in D. hannoverana in all cases. Furthermore, D. hannoverana is more evolute whereas the whorl section of D. pinguis is more compressed and has no furrows limiting the keel. Both morphologies occur in equivalent or the same beds in many localities where they coexist with D. hebridica. As indicated above, Morton (1972: 517) proposed a dimorphic relationship of D. hannoverana [M] with D. hebridica [M] on the one hand with D. pinguis [m] on the other.
DISTRIBUTION
The type comes from Galgenberg near Hildesheim (Germany). In Germany, this species is characteristic of the Pinguis Subzone (Pinguis horizon), for which German authors (Dorn 1935; Buck et al. 1966; Huf 1968; Dietl 1977; Dietl et al. 1984, Metz 1990; Schweigert et al. 2007; Dietze et al. 2008, 2009, 2011a, 2013, 2015, 2017) place it at the base of the Humphriesianum Zone, which is equivalent to the Hebridica Subzone (the upper part of the Propinquans Zone), of current British authors (Morton 1975, 1976; Callomon & Chandler 1990; Chandler et al. 2006, 2017; Chandler & Whicher 2015). In this stratigraphic interval (Hebridica Subzone) is cited in France (Pavia 1983, Rioult et al. 1997; De Baets et al. 2008); Hungary (Galácz et al. 2015); Portugal (Fernández-López et al. 1988); Morocco (Sadki 1996); and Spain, in the Iberian Cordillera (Fernández-López 1985) and the Subbetic domain (Sandoval 1983, 1990). The Subbetic specimens come from the Propinquans Zone (Hebridica Subzone) of Sierra de Alta Coloma area (sections JAC3, JAC3’and JAC11) and Barranco de Agua Larga (section JAQ1; Jaén Province).
description: Published as part of Sandoval, José, 2022, Sonniniidae Ammonitina, Middle Jurassic from Southern Spain: taxonomic, biostratigraphical and palaeobiogeographical analysis, pp. 801-851 in Geodiversitas 44 (27) on pages 843-844, DOI: 10.5252/geodiversitas2022v44a27, http://zenodo.org/record/7150329