Maccoyoceras saharensis Korn & Bockwinkel 2022, sp. nov.
Creators: name: Korn, Dieter
name: Bockwinkel, Jürgen
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Cephalopoda
Nautilida
Trigonoceratidae
Maccoyoceras
Maccoyoceras saharensis

description: Maccoyoceras saharensis sp. nov.
urn:lsid:zoobank.org:act: 029ECCD2-153E-4624-8C6B-B1D24CF0E940
Figs 26–27, Table 15
Diagnosis
Species of Maccoyoceras with subquadrate whorl profile (ww/wh ~1.05), venter slightly flattened, ventrolateral shoulder broadly rounded. Whorls not embracing.
Etymology
Named after the occurrence in the Sahara Desert.
Type material
Holotype ALGERIA • Mouydir, south of Oued Temertasset (locality MOU-A); Argiles de Teguentour (Upper Pericyclus-Progoniatites Assemblage; early late Tournaisian); Korn et al. 2002 Coll.; illustrated in Fig. 26A; MB.C.30480.1.
Paratypes ALGERIA • 1 specimen; Mouydir, south of Oued Temertasset (locality MOU-D1); Argiles de Teguentour (Upper Pericyclus-Progoniatites Assemblage; early late Tournaisian); Korn et al. 2002 Coll.; illustrated in Fig. 26B; MB.C.30481 • 7 specimens; Mouydir, south of Oued Temertasset (localities MOU-A, MOU-B5, MOU-E07, MOU-D2); Argiles de Teguentour (Upper Pericyclus-Progoniatites Assemblage; early late Tournaisian); Korn et al. 2002 Coll.; MB.C.30480.2 – MB.C.30480.3, MB.C.30482.1 – MB.C.30482.2, MB.C.30483.1 – MB.C.30483.2, MB.C.30484.
Description
Holotype MB.C.30480.1 is the fragment of a phragmocone of a quarter whorl length (Fig. 26A); it has a whorl height of 16 mm. The whorl profile is subquadratic with flattened, very weakly convergent flanks, a broadly rounded venter and a broadly rounded dorsum (Fig. 27A). The internal mould shows no ornament, but very faint remnants of spiral striation are visible. The suture line extends with a slight
depression on the venter, a slightly deeper, very broadly rounded lobe on the flank and a very shallow internal lobe (Fig. 27B).
Paratype MB.C.30481 shows the chambered remains of two whorls that touch but do not overlap (Fig. 26B). On the outer whorl with 12 mm whorl height, the profile is subquadrate (ww/wh =1.04) with a wider, flattened venter, weakly divergent, also flattened flanks and a more tightly rounded dorsum (Fig. 27C). The penultimate whorl, 3.8 mm high, is rounded-triangular in profile and somewhat depressed (ww/wh =1.28). The suture line is similar to that of the holotype, but shows a higher ventral area with a slightly deeper external lobe (Fig. 27D).
Remarks
Maccoyoceras saharensis sp. nov. differs from the other species of the genus by the whorl profile form with a strongly rounded ventrolateral shoulder. Another difference could be the strength of the ornament; in M. saharensis sp. nov. no spiral lines were impressed into the internal mould. However, since no shell specimens of the new species are known, it is impossible to say whether spiral lines were actually present. It is therefore also possible that the new species belongs to another genus, for example Lispoceras.
description: Published as part of Korn, Dieter & Bockwinkel, Jürgen, 2022, Early Carboniferous nautiloids from the Central Sahara, southern Algeria, pp. 67-108 in European Journal of Taxonomy 831 on pages 99-101, DOI: 10.5852/ejt.2022.831.1871, http://zenodo.org/record/6885198