Late Givetian ammonoids from Hassi Nebech (Tafilalt Basin, Anti-Atlas, southern Morocco)

Abstract

The Hassi Nebech area of the SE Tafilalt (Tafilalt Basin, Anti-Atlas, Morocco) yielded the richest and most diverse late Givetian ammonoid fauna on a global scale. Above the distinctive regional "Lower Marker Bed" (<i>Synpharciceras clavilobum</i> Zone), abundant loosely collected limonitic specimens derive from hypoxic shales of the <i>Taouzites taouzensis</i> to <i>Petteroceras errans</i> zones. The ontogenetic morphometry and intraspecific variability of a total of 30 species representing five families, the Acanthoclymeniidae, Taouzitidae, Pharciceratidae, Petteroceratidae, and Tornoceratidae, are documented. New taxa are: <i>Pseudoprobeloceras praecox</i> n. sp., <i>Scaturites minutus</i> n. gen. n. sp., <i>Darkaoceras velox</i> n. sp., <i>Pharciceras decoratum</i> n. sp., <i>Ph. fornix</i> n. sp., <i>Ph. subconstans</i> n. sp., <i>Ph. involutum</i> n. sp., <i>Lunupharciceras incisum</i> n. sp., <i>Transpharciceras procedens</i> n. gen. n. sp., <i>Stenopharciceras progressum</i> n. sp., <i>Pluripharciceras</i> n. gen. (type species: <i>Synpharciceras plurilobatum</i> Petter, 1959), <i>Plu. orbis</i> n. sp., <i>Synpharciceras frequens</i> n. sp., <i>Lobotornoceras bensaidi</i> n. sp., <i>Nebechoceras eccentricum</i> n. gen. n. sp., and <i>Phoenixites lenticulus</i> n. sp. The documentation of conch and particularly suture ontogeny and intraspecific variability necessitates a revised diagnosis for ten taxa. <i>Manticoceras pontiformis</i> Termier & Termier, 1950, <i>Probeloceras costulatum</i> Petter, 1959, and <i>Pseudoprobeloceras nebechense</i> Bensaïd, 1974 are regarded as subjective junior synonyms of <i>Ps. pernai</i> (Wedekind, 1918). <i>Sandbergeroceras acutum</i> Termier & Termier, 1950 is a subjective synonym of <i>Taouzites taouzensis</i> (Termier & Termier, 1950). <i>Pharciceras applanatum</i> Bensaïd, 1974 is transferred to <i>Extropharciceras</i>. Other forms (<i>Ph</i>. aff. <i>tridens</i>, <i>Ph</i>. cf. <i>subconstans</i> n. sp., <i>Extropharciceras</i> n. sp. 2, <i>Ex</i>. cf. <i>arenicum</i>, <i>Ex</i>. cf. <i>applanatum</i>, <i>Synpharciceras</i> sp., <i>Plu</i>. cf. <i>plurilobatum</i>) are described in open nomenclature. <br><br> doi:<a href="http://dx.doi.org/10.1002/mmng.201300001" target="_blank">10.1002/mmng.201300001</a>