Harpoceratinae Neumayr, 1875

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 : 248-250

Subfamily Harpoceratinae Neumayr, 1875 Genus Protogrammoceras Spath, 1913

Subgenus Protogrammoceras Spath, 1913 Protogrammoceras (Protogrammoceras) cf. celebratum ( Fucini, 1900)

Fig. 4H.

1900 cf. Grammoceras celebratum ; Fucini 1900: 41, pl. 10: 1, 2.

1989 cf. P. (Protogrammoceras) celebratum ( Fucini, 1900) ; Meister 1989: 40, pl. 3: 14, 15; pl. 4: 1 (with synonymy).

1997 cf. Protogrammoceras celebratum (Fucini) ; Dommergues et al. in Cariou and Hantzpergue 1997: pl. 8: 3.

1998 cf. Protogrammoceras gr. celebratum ( Fucini, 1900) ; Géczy and Meister 1998: 108, pl. 12: 7–9; pl. 13: 1–3, 5.

Material.—Two fragmentary specimens from Shahmirzad (050514−6/11, 050514−6/12).

Description.—The figured specimen (050514−6/12) is a planulate and evolute member of the Harpoceratinae with a high−ovate acute whorl cross−section and a distinct, high keel. The ribs are simple, falciform, fine and dense, projecting strongly on the venter.

Discussion.—The strongly falciform and fine ribbing resembles P. celebratum . The specimens therefore is placed, with reservation, within the range of variation of the species, as given by Ferretti (2002: 208).

Stratigraphic and geographic range.—Shahmirzad, level II. P. celebratum is widely distributed within eastern Europe and the Mediterranean, occurring in the Amaltheus stokesi Subzone of the Amaltheus margaritatus Zone. In Iran, Protogrammoceras is a very rare taxon. At Shahmirzad, it was collected just below the beds with Amaltheus .

Subgenus Matteiceras Wiedenmayer, 1980 Protogrammoceras (Matteiceras) cf. nitescens ( Young and Bird, 1828)

Fig. 4K.

1828 cf. Ammonites nitescens ; Young and Bird 1828: 257.

1992 cf. Protogrammoceras (Matteiceras) nitescens ( Young and Bird, 1828) ; Howarth 1992: 66, pl. 4: 4–6; pl. 5: 2; text−fig. 12 (with synonymy).

Material.—One fully septate inner whorl from Shahmirzad (050514−6/10).

Dimensions (in mm)

Specimen D U H W

050514−6/10 26 34 39 ~38

Description.—A relatively evolute form with a slightly higher than wide, ovate whorl cross−section. The venter is fairly broad, with a well−defined keel. The ribs are moderately coarse, simple or indistinctly bifurcating close to the umbilicus. On the inner part of the flank the ribs are prorsiradiate. On the outer part of the flank the ribs bend backward and become rursiradiate. Near the venter the ribs become raised and project strongly on the venter but fade before reaching the keel.

Discussion.—The described specimen is a fully septate inner whorl. Although incomplete, it shows some resemblance to P. (M.) nitescens , especially to the specimen figured by Meister (1989: pl. 3: 12). Compared with the latter, our specimen is less evolute and the ribbing less coarse.

Stratigraphic and geographic range.—Shahmirzad, level II. In Europe, P. (M.) nitescens is not uncommon in the Amaltheus stokesi Subzone. In Iran, it has been encountered for the first time, just below the beds with Amaltheus .