Stroboceras mane, Korn & Bockwinkel, 2022

Korn, Dieter & Bockwinkel, Jürgen, 2022, Early Carboniferous nautiloids from the Central Sahara, southern Algeria, European Journal of Taxonomy 831, pp. 67-108 : 81-82

Stroboceras mane sp. nov.

urn:lsid:zoobank.org:act:D423198E-EA1D-44F1-A1E3-C1E31F6FDC4E

Fig. 10 , Table 5

Diagnosis

Species of Stroboceras with weakly depressed, rounded-trapezoidal whorl profile (ww/wh ~1.45), venter strongly flattened, ventrolateral shoulder angular with sharp longitudinal ridges. Whorls not embracing. Whorl profile with wide longitudinal groove on the outer flank near the ventrolateral margin.

Etymology

From the Latin ‘ mane ’, meaning ‘early, morning’ and referring to the stratigraphically early occurrence of the species.

Type material

Holotype ALGERIA • Mouydir , south of Oued Temertasset (locality MOU-Y); Argiles de Teguentour (Lower Pericyclus-Progoniatites Assemblage; early late Tournaisian); Korn et al. 2002 Coll.; illustrated in Fig. 10A ; MB.C.30458.1 .

Paratype ALGERIA • Mouydir , south of Oued Temertasset (locality MOU-Y); Argiles de Teguentour (Lower Pericyclus-Progoniatites Assemblage; early late Tournaisian); Korn et al. 2002 Coll.; MB.C.30458.2 .

Description

Holotype MB.C.30458.1 is a phragmocone fragment with about 22 mm conch diameter; it is partly embedded in a haematite nodule ( Fig. 10A ) and was sectioned for the study of the whorl profile. The conch is discoidal and evolute (ww/dm=0.51; uw/dm= 0.45). The whorl profile is rounded-trapezoidal with almost flat venter separated from the convex flanks by an angular ventrolateral shoulder. Next to this shoulder is a shallow, wide longitudinal groove ( Fig. 10B ). The whorls apparently do not touch each other, but this may be caused by dissolution of the shell wall.

The suture line has a very broad external lobe, an angular ventrolateral saddle in the area of the ventrolateral shoulder and a flat, somewhat undulating lateral lobe ( Fig. 10C ). The siphuncle has a subcentral position.

Remarks

Stroboceras mane sp. nov. is an ancestral species of the genus and differs from almost all other species by the non-embracing whorls. Another distinguishing criterion is the very weak formation of longitudinal ridges and grooves.

Figures

Fig. 10. Stroboceras mane sp. nov. from Oued Temertasset, holotype MB.C.30458.1 (Korn et al. 2002 Coll.). A. Ventral and lateral views. B. Cross section. C. Suture line, at ww =9.9 mm, wh=5.5 mm. Scale bar units =1 mm.

Tables

Table 5. Conch dimensions (in mm) and ratios of Stroboceras mane sp. nov.

Specimen	dm	ww	wh	uw	ah	ww/dm	ww/wh	uw/dm	WER	IZW
MB.C.30458.1	22.0	11.2	7.6	9.9	7.6	0.51	1.47	0.45	2.34	0.0