Stroborineceras insalahensis, 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 : 75-77

Stroborineceras insalahensis gen. et sp. nov.

urn:lsid:zoobank.org:act:F19AF373-B30D-4DCA-ADDE-C0C2678A753F

Figs 6–7 , Table 2

Diagnosis

Species of Stroborineceras gen. nov. with depressed, rounded-triangular whorl profile (ww/wh ~1.50), venter strongly flattened, ventrolateral shoulder subangular with sharp longitudinal ridges. Whorls not embracing. Ornament with fine spiral ridges in the submarginal ventral position; five or six spiral ridges are located on the flank.

Etymology

Named after the town of In Salah in the central Sahara Desert.

Type material

Holotype ALGERIA • Mouydir , south of Oued Temertasset (locality MOU-E07); Argiles de Teguentour (Upper Pericyclus-Progoniatites Assemblage; early late Tournaisian); Korn et al. 2002 Coll.; illustrated in Fig. 6B ; MB.C.30445.1 .

Paratypes ALGERIA • 2 specimens; Mouydir , south of Oued Temertasset (locality MOU-E07); Argiles de Teguentour (Upper Pericyclus-Progoniatites Assemblage; early late Tournaisian); Korn et al. 2002 Coll.; illustrated in Fig. 6A, C ; MB.C.30445.2 – MB.C.30445.3 • 1 specimen; Mouydir , south of Oued Temertasset (locality MOU-D2); Argiles de Teguentour (Upper Pericyclus-Progoniatites Assemblage; early late Tournaisian); Korn et al. 2002 Coll.; illustrated in Fig. 6D ; MB.C.30446.1 • 18 specimens; Mouydir , south of Oued Temertasset (localities MOU-D2, MOU-A, MOU-C5, MOU-D1, MOU-E06, MOU-V, MOU-Z); Argiles de Teguentour (Upper Pericyclus-Progoniatites Assemblage; early late Tournaisian); Korn et al. 2002 Coll.; MB.C.30446.2 , MB.C.30447.1–MB.C.30447.4 , MB.C.30448.1– MB.C.30448.2 , MB.C.30449.1–MB.C.30449.6 , MB.C.30450 , MB.C.30451 , MB.C.30452.1– MB.C.30452.3 • 1 specimen; Sebkha de Timimoun 11 km south-west of Timimoun (locality TIM-B0); Grès de Kahla supérieur (Upper Pericyclus-Progoniatites Assemblage; early late Tournaisian); Korn et al. 2002 Coll.; MB.C.30453 .

Description

Holotype MB.C.30445.1 is a whorl fragment of about 90 degrees angular length, consisting of the last chambers of the phragmocone and part of the body chamber ( Fig. 6B ). The maximum whorl height is 11 mm. The whorl profile is rounded-triangular and depressed (ww/wh = 1.51) with a flattened venter and an almost semi-circular area encompassing the flanks and dorsum ( Fig. 7A ); the ventrolateral shoulder is subangular. The specimen bears at least eight longitudinal lines, two of which are on the edge of the venter and six on the flank. The suture line shows a broad, almost semi-circular external lobe, a tightly rounded ventrolateral saddle and a shallow and very broad lateral lobe. On the dorsum the suture line shows an almost straight course ( Fig. 7E ).

The paratypes illustrate that the variation is quite low; all specimens show very similar whorl profiles, ornament and suture line. Compared to the holotype, the paratype MB.C.30445.2 ( Fig. 6A ) has more strongly developed spiral lines on the flanks and the paratypes MB.C.30445.3 ( Fig. 6C ) and MB.C.30446.1 ( Fig. 6D ) show slightly more distinct submarginal ridges on the venter.

Remarks

Stroborineceras insalahensis gen. et sp. nov. differs from S. felis gen. et sp. nov. by the more depressed whorl profile (ww/wh = 1.55 in S. insalahensis gen. et sp. nov. but only 1.25 in S. felis gen. et sp. nov.), by the flattened or weakly convex venter (concave in S. felis gen. et sp. nov.) and by the considerably stronger spiral lines (weakly developed and absent on the venter in S. felis gen. et sp. nov.).

Figures

Fig. 6. Stroborineceras insalahensis gen. et sp. nov. from Oued Temertasset (all Korn et al. 2002 Coll.). A. Paratype MB.C.30445.2. B. Holotype MB.C.30445.1. C. Paratype MB.C.30445.3. D. Paratype MB.C.30446.1. Scale bar units =1 mm.

Fig. 7. Stroborineceras insalahensis gen. et sp. nov. from Oued Temertasset (all Korn et al. 2002 Coll.). A. Whorl profile of holotype MB.C.30445.1. B. Whorl profile of paratype MB.C.30446.1. C. Whorl profile of paratype MB.C.30445.3. D. Whorl profile of paratype MB.C.30445.2. E. Suture line of holotype MB.C.30445.1, at ww =15.3 mm, wh=10.2 mm. F. Suture line of paratype MB.C.30445.3, at ww =15.1 mm, wh =9.8 mm. Scale bar units =1 mm.

Tables

Table 2. Conch dimensions (in mm) and ratios of Stroborineceras insalahensis gen. et sp. nov.

Specimen	dm	ww	wh	uw	ah	ww/dm ww/wh uw/dm			WER	IZW
MB.C.30445.3	–	15.9	10.4	–	–	–	1.53	–	–	–
MB.C.30445.1	–	15.6	10.3	–	–	–	1.51	–	–	–
MB.C.30446.1	–	14.5	9.3	–	–	–	1.56	–	–	–
MB.C.30445.2	–	13.6	9.2	–	–	–	1.49	–	–	–