Ludwigella Buckman, 1901

Seyed-Emami, Kazem, Fürsich, Franz T., Wilmsen, Markus, Majidifard, Mahmoud R. & Shekarifard, Ali, 2008, Lower and Middle Jurassic ammonoids of the Shemshak Group in Alborz, Iran and their palaeobiogeographical and biostratigraphical importance, Acta Palaeontologica Polonica 53 (2), pp. 237-260 : 254-255

Subgenus Ludwigella Buckman, 1901

Graphoceras (Ludwigella) cornu ( Buckman, 1887) Fig. 6B, E.

1887 Ludwigia cornu ; Buckman 1887: pl. 4: 3, 4.

1969 Graphoceras (Ludwigella) cornu ( Buckman, 1887) ; Contini 1969: 73, pl. 5: 8, 9; pl. 12: 13–15, 17; pl. 24: 55–57; text−figs. 20–23 (with synonymy).

1971 Graphoceras (Ludwigella) cornu ( Buckman, 1887) ; Caloo 1971: pl. 1: 3–6, 10–12; pl. 2: 16, 19; pl. 3: 23–28, 30, 31.

2004 Graphoceras cornu ( Buckman, 1887) ; Myczyński 2004: 102, figs. 29/4, 30/8.

Material.— Three specimens from Kuhe Bashm (050511− 15/1, 050511−15/8, 050511−15/9).

Dimensions (in mm)

Specimen D U H W

050511−15/9 26 ~32 ~43 ~32

050511−15/8 29 29 ~44 ~29

Description.—Moderately involute Graphoceratinae with high−ovate, slightly fastigate whorl cross−section and a sharp keel. The ribbing is strongly falcate. The prorsiradiate primary ribs bifurcate mostly within the inner half of the flank. The secondary ribs are strongly rursiradiate, slightly concave and nearly angular to the primaries.

Discussion.—Our specimens falls well within the range of variation of the species as given by Contini (1969: especially

pl. 12: 5). Stratigraphic and geographic range.—Kuhe Bashm, level

IX. Together with Graphoceras (G.) concavum from the Late Aalenian, Otoceras concavum Zone.

Graphoceras (Ludwigella) cf. rudis (Buckman, 1889) Fig. 6D, F.

1889 cf. Ludwigia rudis ; Buckman 1889: 103, pl. 15: 12.

1967 cf. Ludwigia (Ludwigella) rudis Buckman 1889 ; Seyed−Emami 1967: 61, pl. 2: 3; pl. 7: 16.

1969 cf. Graphoceras (Ludwigella) rudis (Buckman) 1889 emend.; Contini 1969: 71, pl. 5: 7; pl. 22: 6–12; pl. 14: 52–53; text−fig. 19 (with synonymy).

2001 cf. Graphoceras (Ludwigella) rudis Buckman ; Rulleau et al. 2001: pl. 23: 6a, b, 7a, b.

Material.—Two fragmentary specimens from Sharif−Abad (050512−11/4, 050512−11a/13).

Description.—The fragmentary specimens are relatively evolute, with a rectangular−ovate whorl cross−section, a broad venter and a low blunt keel. The ornamentation consists of falcate, blunt ribs, irregularly bifurcating near to the umbilicus.

Discussion.—The fragmentary specimens is closely comparable to the specimens figured by Rulleau et al. (2001: pl. 23: 6, 7).

Stratigraphic and geographic range.—Sharif−Abad, level G. Late Aalenian, Otoceras concavum Zone.