Early Cretaceous Freshwater Fish Fauna in Kyushu, Japan

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178 Yoshitaka Yabumoto Horizon. The First Formation (the lower formation, Wb correlated to the Sengoku Formation) of the Wakino Subgroup in the Kwanmon Group, the Lower Cretaceous. Description. The snout is rounded. The outline ofthe head dorsal margin is slightly convex. The pectoral fin rays and the pelvic fin rays are visible. The gape of the mouth is large. The lower jaw is long and narrow. The dentary bears large canine like teeth. The suture between the dentary and the anglo-articular is not visible. The premaxilla and the maxilla bear large canine like teeth. The teeth ofjaws are almost same in size. The posterior end of the lower jaw is placed behind the orbit. Eight canine like teeth are preserved on the parasphenoid at about center of the orbit. The parasphenoid teeth are almost same with the teeth ofjaws in size. There are villiform teeth on the endopterygoid. There is a series of median supraneurals. The supraneurals are cylindrical. Remarks. This species differs from other species of the genus, Aokiichthys, in having the combination of following characters. The snout is rounded. The length of PREM OEN Fig. 51. Aokiichthys sp., KMNH VP 100,159.
Early Cretaceous Freshwater Fish Fauna in Kyushu, Japan 179 lower jaw is contained 1.3 times in the head length. The parasphenoid teeth are almost same with the teeth of jaws in size. The position of pelvic fin indicates the deep body (Fig. 51). The present author does not describe it as a new species, because the specimen is too incomplete. Family Wakinoichthiidae nov. Diagnosis. This new family differs from other families of the Osteoglossiformes in the following combination of characters. The body is slender, and the bodydepth is contained 6 times or more in the standard length. The head length is contained 4 times or more in the standard length. The long pectoral fin extends beyond the pelvic fin insertion. The gape ofthe mouth is large and the lower jaw is long with small canine-like teeth on the dentary. Large teeth are absent on the parasphenoid. The frontals are long and narrow. The number of principal caudal fin rays is 18 (1,8,8,1). The number of hypurals is 7. The first uroneural does not extend to the second preural centrum. Two parts of the first ural centrum are present. The neural arch and spine of the first preural centrum are complete. The number of vertebrae is 48. The median supraneurals are broad. The dorsal origin is behind the anal origin. The dorsal fin base is about half of the anal fin base. The end of the dorsal fin base does not reach the end of the anal fin base. Diagnosis. Type species. Genus Wakinoichthys gen. nov. As for the family, monotypic genus. Wakinoichthys aokii sp. nov. Etymology. The generic name, Wakinoichthys consists of Wakino, the name of the formation in which the type specimen was yielded, and ichthys, a Greek word meaning fish. Remarks. The presence ofthe parasphenoid teeth is not clear (at least large teeth are absent on the parasphenoid), but the following combination of characters indicate that the Wakinoichthiidae is a member ofthe teleostean fish order Osteoglossiformes: 1) the median fins are relatively posterior in position, 2) the premaxilla and dentary have canine like teeth, 3) the endopterygoid has villiform teeth, 4)the pectoral fin elongates, 5) the series ofsupraneurals are present, 6) the anterior and the posterior parts ofthe first ural centrum are present, 7) the straplike uroneurals are present, 8) the number of hypural is seven, 9) the neural arch and spine of the first preural centrum are complete, 10) the number of principal caudal fin rays, is 18. Seven families and about twenty genera of the Osteoglossomorpha are known
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Early Cretaceous Freshwater Fish Fauna in Kyushu, Japan

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