マダガスカル産三畳紀のシーラカンスの新種Whiteia uyenoteruyai (肉鰭亜綱，シーラカンス下綱)とワイテイア科の古生物地理

抄録

Three genera and four species of coelacanths, which are Piveteauia madagascariensis LEHMAN, Rhabdoderma madagascariensis (WOODWARD), Whiteia woodwardi MOY-THOMAS, W. tuberculata MOY-THOMAS have been described from the Lower Triassic of Madagascar. In the present study, we examined a coelacanth fossil from Madagascar deposited in Aquamarine Fukushima and determined it as a new species of the genus Whiteia of the family Whiteiidae. This new species, W. uyenoteruyai sp. nov. is distinguished from other species of the genus in having the combination of the following characters: 20 or more rows of fine long and short ridges separated from each other on scales, ridged ornamentation of lateral line scales on the sensory canal, eight rays on the first dorsal fin, no denticle on fin rays of the first dorsal fin and caudal fins (the third dorsal fin and the second anal fin) and ridges on the posteroventral portion of the operculum. The whiteiid coelacanths are most abundant in the Early Triassic and the origin is probably during the Early Triassic in shallow water along the northern coast of Pangea. Guizhoucoelacanthus guanlingensis LIU et al. from the Middle and Upper Triassic of China is probably derived from the Early Triassic Whiteia, which is most diversified among the family and survived with one species, W. oishii from the Late Triassic of West Timor (237–207 Ma), Indonesia. Atacamaia solitaris from the Late Jurassic of Chile is probably derived from Axelia or Wimania.