Trilobitoceras peculiaris gen. et sp. nov.

urn:lsid:zoobank.org:act: D75CCA9E-1207-4384-8848-3AF713D0D894

Figs 23–24, Table 13

Diagnosis

Species of Trilobitoceras gen. nov. with moderately depressed whorl profile (ww/wh ~ 1.65). Suture line with a broadly rounded median saddle.

Etymology

From the Latin ‘ peculiaris ’, meaning ‘peculiar’ and referring to the unusual conch shape.

Type material

Holotype ALGERIA • Mouydir, south of Oued Temertasset (locality MOU-Z); Argiles de Teguentour (Upper Pericyclus-Progoniatites Assemblage; early late Tournaisian); Korn et al. 2002 Coll.; illustrated in Fig. 23A; MB.C.30477.

Paratype 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. 23B; MB.C.30478 .

Description

Holotype MB.C.30477 is a phragmocone fragment with almost half a whorl length (Fig. 23A). It has a depressed whorl profile (ww/wh= 1.63) with a broadly rounded venter characterised by two deep and wide ventral grooves. The flanks are almost parallel in their middle and the umbilical wall is almost flat (Fig. 24A). The suture line, whose course is determined by the shape of the whorl profile, has a very wide external lobe in which a low, broadly rounded median saddle rises (Fig. 24B).

Paratype MB.C.30478 is a fragment consisting of only two chambers of the phragmocone (Fig. 23B). The conch geometry is very similar to the holotype, although the ww/wh ratio is slightly higher with a value of 1.72. (Fig. 24C) The suture line is also similar to the holotype; however, the specimen also shows the rather narrow, rounded V-shaped internal lobe (Fig. 24D).

Remarks

Trilobitoceras peculiaris gen. et sp. nov. has a very similar conch morphology like T. planidorsale, but differs in the course of the suture line: T. peculiaris gen. et sp. nov. possesses a mid-ventral saddle but T. planidorsale possesses a mid-ventral lobe.