Aphelaeceras azzelmattiense, 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 : 97-98

Aphelaeceras azzelmattiense sp. nov.

urn:lsid:zoobank.org:act:88F44087-A4B4-4FD7-9C36-CF189028289E

Fig. 25 , Table 14

Diagnosis

Species of Aphelaeceras reaching about 130 mm conch diameter. Conch with weakly compressed whorl profile (ww/wh ~ 0.65); venter double-keeled with narrow longitudinal groove; flanks convergent, umbilical margin subangular, umbilical wall oblique, weakly concave. Shell surface nearly smooth.

Etymology

Named after the type locality Gara Azzel Matti.

Type material

Holotype ALGERIA • Ahnet , west-southwest of Gara Azzel Matti; ‘ Dalle des Iridet’ (Ammonellipsites-Merocanites Assemblage; Tournaisian–Viséan boundary interval); Wendt and Kaufmann 1995 Coll.; illustrated in Fig. 25 ; MB.C.30479.1 .

Paratype ALGERIA • 1 specimen; Ahnet , west-southwest of Gara Azzel Matti; ‘ Dalle des Iridet’ (AmmonellipsitesMerocanites Assemblage; Tournaisian–Viséan boundary interval); Wendt and Kaufmann 1995 Coll.; MB.C.30479.2 .

Description

Holotype MB.C.30479.1 is an incomplete, partially broken and desert-eroded specimen with a conch diameter of almost 120 mm ( Fig. 25 ). The conch is very thinly discoidal (ww/dm=0.19) with a rather wide umbilicus (uw/dm=0.44) and moderate coiling rate (WER =1.95). The conspicuous, lyriform whorl profile is widest at the distinct, subangular umbilical edge. It shows an oblique, concave umbilical wall, convergent flanks and a double-keeled venter with a deep longitudinal median groove.

Paratype MB.C.30479.2 is an incomplete specimen with 60 mm diameter, which largely complements the morphology of the holotype.

Remarks

Aphelaeceras azzelmattiense sp. nov. differs from all the other species of the genus in the concave umbilical wall.

Figures

Fig. 25. Aphelaeceras azzelmattiense sp. nov., holotype MB.C.30479.1 (Wendt & Kaufmann 1995 Coll.) from Azzel Matti. Scale bar units =1 mm.

Tables

Table 14. Conch dimensions (in mm) and ratios of Aphelaeceras azzelmattiense sp. nov.

Specimen	dm	ww	wh	uw	ah	ww/dm	ww/wh	uw/dm	WER	IZW
MB.C.30479.1	119.2	22.9	35.6	52.9	33.8	0.19	0.64	0.44	1.95	0.05