pt. 1981  Convoluticeras.-Ruan:27.
     2001  Irdanites Klug: 506.
     2002  Irdanites.-Korn & Klug: 68.

Type species: Irdanites korni Klug, 2001, 507 [OD].

Klug, 2001, p.506: Conch of small to moderately large size, advolute or evolute and thinly discoidal to discoidal; without or with a small imprint zone. Whorl cross section oval to subcircular. Protoconch ovoid and large (0.9 to 1 mm), umbilical window large. Moderately wide to wide umbilicus. High to very high whorl expansion rate (2.4 to 3.5 at dm > 15 mm). Sculpture with shallow ribs with gently rursiradiate or rectiradiate direction which fade out dorsally and ventrally. Coarse growth lines parallel to the ribs with biconvex course, with a shallow lateral sinus, a distinct ventrolateral salient of varying size, and a deep ventral sinus; the growth lines are sometimes fasci- or virgatipartite. Suture line with a small external lobe, a broad lateral lobe, and sometimes with a small internal lobe.

Comparisons (Klug, 2001, p.506): Irdanites is separated from Palaeogoniatites HYATT 1900 because the adult conch of Irdanites is advolute. The growth lines of Palaeogoniatites have a significantly lower ventrolateral salient and a shallower ventral sinus (at dm > 13 mm). Additionally, the whorls of Irdanites have an oval cross section. In contrast to Irdanites, Archanarcestes BECKER & HOUSE 1994 has a distinct imprint zone, growth lines with deep lateral and ventral sinuses and a very high ventrolateral salient, and a well defined V-shaped internal lobe. However, a close phylogenetic relation of these two genera is likely. Teicherticeras ERBEN 1960 differs from Irdanites in having a subrectangular to subtrapezoidal and laterally flattened whorl cross section, in lacking a lateral sinus in growth lines and ribs, and many species of the former genus have a lower whorl expansion rate.

A:   Conch advolute or evolute, Ww/D = 0.3 - 0.4.
B:   High ventrolateral salient, deep ventral sinus.
C:   Riblets fascipartite.
G:   EL or ELI.