Merocanites consequius, Korn, 2025

Merocanites consequius sp. nov.

urn:lsid:zoobank.org:act:15FA1A69-02FA-458B-9EDC-8877AC2C147C

Fig. 5 View Fig ; Table 2 View Table 2

Diagnosis

Species of Merocanites with a strongly applanate whorl cross section (ww/wh ~ 0.60 at 90 mm conch diameter); flanks flattened and subparallel and separated from the rounded venter by a rounded ventrolateral shoulder; umbilical margin rounded. Suture line with a small, V-shaped external lobe; three lobes present on the flanks, the adventive lobe is asymmetric with a steep dorsal flank, followed by the lateral lobe and the second umbilical lobe, which closely resemble each other. Width of the lateral lobe 0.26–0.28 of its depth.

Etymology

After the Latin ‘ consequius ’ (adj. masc.) = ‘following’, because of the late occurrence of the species.

Type material

Holotype

MOROCCO – Anti-Atlas • Gara el Itima , near locality GI-J; 31°02.747′ N, 3°42.429′ W; Zrigat Formation, horizon GI-1 (Late Viséan); 2007; Korn et al. leg.; MB.C.32199.1 ; illustrated in Fig. 5B View Fig .

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Paratypes

MOROCCO – Anti-Atlas • 3 specs; same data as for the holotype; MB.C.32199.2 to MB.C.32199.4 .

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Description

Holotype MB.C.32199.1 is the fragment of a phragmocone with a whorl height of 31 mm ( Fig. 5B View Fig ), which leads to a reconstructed phragmocone diameter of about 90 mm ( Table 2 View Table 2 ). The ww/wh ratio is nearly 0.60. The whorl profile shows a semicircular venter, almost parallel and flattened flanks, a rounded umbilical margin and convex umbilical wall. The whorl embraces very little of the previous one.

The suture line has a small, V-shaped external lobe that is only half as deep as the three lobes on the flank ( Fig. 5C View Fig ). The outer of these three lobes, the adventive lobe, is asymmetrical with a strongly curved ventral and an almost vertical dorsal flank. Two more, almost identical lobes follow on the flank. Both are very narrow and deep; they are slightly wider than the neighbouring saddles. These lobes are slightly pouched and the saddles appear slightly inflated. On the umbilical wall there is another, short and V-shaped lobe. The internal lobe has parallel walls and is very narrow and very deep with nearly parallel flanks.

The larger paratype MB.C.32199.2 (71 mm wh) is also a fragment of the phragmocone and shows the same morphology as the holotype ( Fig. 5A View Fig ). The suture line is almost identical to that of the holotype.

Remarks

All species of Merocanites possess similar conch shapes, but differences can be recognised in the whorl profile, the width of the umbilicus and the suture line. It is important to note that the suture line changes during ontogeny, with the lobes on the flank becoming increasingly symmetrical and narrower during ontogeny. Any comparison of species must take this into account. A potential phylogenetic trend may also be discernible, with younger species displaying narrower lobes compared to older ones.

Merocanites consequius belongs to those species that already exhibit very narrow lobes at a relatively early ontogenetic stage, with a whorl height of 30 mm. The lateral lobe has a width-to-depth ratio of 0.26, compared to approximately 0.30 in M. quadrilobus . A similar suture line to M. consequius can be found in M. ogivalis , but this species differs from M. consequius by having a significantly narrower umbilicus (uw/dm = 0.32) than M. consequius (uw/dm> 0.40).