Goniatites rodioni Korn & Ebbighausen, 2006

Goniatites rodioni Korn & Ebbighausen, 2006 View in CoL

Fig. 2 View Fig

Goniatites rodioni Korn & Ebbighausen View in CoL in Klug et al., 2006: 24, text-figs 20–21, 22a.

Goniatites crenistria View in CoL – 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 GoogleMaps .

Description

All the newly available specimens are fragments, with MB.C.32197.1 being the best preserved ( Fig. 2A View Fig ). 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 View Fig ).

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.