Choneziphius Duvernoy, 1851

Lambert O., 2005, Systematics and phylogeny of the fossil beaked whales Ziphirostrum du Bus, 1868 and Choneziphius Duvernoy, 1851 (Mammalia, Cetacea, Odontoceti), from the Neogene of Antwerp (North of Belgium), Geodiversitas 27 (3), pp. 443-497 : 465

Genus Choneziphius Duvernoy, 1851

Choneziphius Duvernoy, 1851: 63 .

Belemnoziphius Huxley, 1864: 395 , partim.

Ziphius Owen, 1870 : pl. 2, fig. 1, partim.

Proroziphius Leidy, 1876: 87 ; 1877: pl. 32, figs 1-4.

TYPE SPECIES. — Ziphius planirostris Cuvier, 1823 by present designation.

OTHER INCLUDED SPECIES. — Choneziphius macrops ( Leidy, 1876) and C. liops Leidy, 1876 (figured in Leidy 1877). EMENDED DIAGNOSIS. — This fossil ziphiid genus differs from all the other known living and fossil ziphiids in: the mesorostral groove dorsally closed at the level of the antorbital noches by the joined medial margins of the premaxillary sac fossae, forming a prominent ridge posteriorly deviated on the left, and separating deeply concave anterior portions of the premaxillary sac fossae. It further differs from:

– Ziphirostrum and Messapicetus in: flatter and lower maxillary surface at the dorsal base of the rostrum; more asymmetrical premaxillary sac fossae (ratio between maximum widths of left and right premaxillae at the level of the fossae lower or equal to 0.65); elevated longitudinal maxillary crest on the supraorbital process;

– Aporotus in: fusion of the elevated premaxillae over the mesorostral groove;

– Ziphius in: dorsal roofing of the mesorostral groove by the premaxillae; less elevated vertex not overhanging the bony nares as clearly as in Ziphius ;

– Tusciziphius in: concavity of the surface of the premaxillary sac fossa anteriorly followed by a deep longitudinal foramen; much narrower transverse premaxillary crests on the vertex.

The vertex is only known from the species C. planirostris .

DISCUSSION

The drawing of the partial rostrum from Suffolk, identified by Lankester (1870: pl. 33, figs 1-4) as Choneziphius packardi is not detailed enough and the fragment is probably too eroded to allow a specific or even generic determination.

The fragmentary C. trachops is similar to C. planirostris ; the only difference clearly noted by Leidy (1877) is the less excavated premaxillary sac fossae. However, this character is demonstrat- ed here as variable in C. planirostris .

C. liops might represent a different species, given its relatively shorter rostrum, with a stronger anterior narrowing.

The holotype of Proroziphius macrops sensu Leidy, 1876 , from the Phosphate Beds of South Carolina, is discussed below, and is considered as a member of the genus Choneziphius , C. macrops . In the same way, the poorly preserved holotype of Proroziphius chonops Leidy, 1877 (USNM 16689) should probably be included in the genus Choneziphius : it shows premaxillary sac fossae separated by a deviated crest, the complete dorsal roofing of the mesorostral groove, and the roughly horizontal dorsal surface of the maxillae at the base of the rostrum, typical of Choneziphius .