Goniatites rodioni Korn & Ebbighausen 2006

Goniatites rodioni Korn & Ebbighausen, 2006 Fig. 2 Goniatites rodioni Korn & Ebbighausen in Klug et al., 2006: 24, text-figs 20–21, 22a. Goniatites crenistria – Delépine 1941: 66, pl. 4 figs 2–3. Diagnosis (from Korn & Ebbighausen, 2006, emended here) Species of Goniatites with a conch reaching a diameter of 70 mm. Conch globular to spindle-shaped at 20 mm diameter (ww/dm 0.90–1.10), pachyconic to globular at 40 mm diameter (ww/dm 0.70–0.90) and pachyconic at 60 mm diameter (ww/dm 0.65–0.75). Umbilicus very narrow in all stages larger than 20 mm dm (uw/dm 0.05–0.15). Shell ornament with crenulated, biconvex and rursiradiate growth lines with prominent dorsolateral projection. External sinus very shallow. Suture line with a moderately narrow external lobe (0.40–0.45 of the external lobe depth) and a low median saddle (0.25–0.35 of the external lobe depth). Type material Holotype MOROCCO – Anti-Atlas • Gara el Itima locality GI-J; Zrigat Formation, horizon GI-1 (Late Viséan); 2004; Ebbighausen and Korn leg.; MB.C.9084.1; illustrated by Korn & Ebbighausen (in Klug et al. 2006: text-fig. 20a–b). Paratypes MOROCCO – Anti-Atlas • 71 specs; same data as for the holotype; 2004; Ebbighausen and Korn leg.; MB.C.9084.2 to MB.C.9084.72. Other material examined MOROCCO – Anti-Atlas • 11 specs; 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.32197.1 to MB.C.32197.11. Description All the newly available specimens are fragments, with MB.C.32197.1 being the best preserved (Fig. 2A). It is from a specimen with a conch diameter of 44 mm, which is spherical and very narrowly umbilicate at this ontogenetic stage (ww/dm = 0.95; uw/dm = 0.11). The suture line has a very narrow, V-shaped external lobe with almost straight flanks. The external lobe, the ventrolateral saddle and the adventive lobe are approximately equally wide; the adventive lobe displays weakly sinuous flanks (Fig. 2B). Remarks (from Korn & Ebbighausen in Klug et al. 2006) A comparison of Goniatites rodioni with the other species of the genus that lack spiral ornament is rather easy. Goniatites sphaericus (Sowerby, 1814) has a similar conch, but differs in the much higher median saddle (0.45 of the external lobe depth) from G. rodioni (0.25). Goniatites crenistria Phillips, 1836 has, unlike G. rodioni, growth lines that run with almost linear course across flanks and venter. In this respect, G. hudsoni Bisat, 1934 and G. americanus Gordon, 1971 resemble G. rodioni, but these species differ in the suture line: G. rodioni has a very narrow external lobe, which is narrower than the adventive lobe than the other two. Furthermore, the growth lines in G. rodioni show a much higher dorsolateral projection.