Early Cretaceous Freshwater Fish Fauna in Kyushu, Japan

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172 Yoshitaka Yabumoto length. The head length is contained 3.4 times in the standard length. The dorsal fin base is contained 2.3 times in the anal fin base. The number ofprincipal dorsal fin rays is 11. There are 11 dorsal fin pterygiophores. The number of principal anal fin rays is 19. There are 19 anal fin pterygiophores. The number ofpectoral fin rays is 10. The dentary bears small canine like teeth on its oral margin. The maxilla bears small teeth almost entirely on its oral margin. The palatine is slender and has minute teeth. The supramaxilla is present. One infraorbital is visible at the postero-ventral corner of the orbit and has a sensory canal along the orbital margin. The total number of vertebrae is 34, with 17 caudal vertebrae. In KMNH VP 100,178, the body depth is contained 2.4 times in the standard length. The head length is contained 3.3 times in the standard length. The dorsal fin base is contained 1.8 times in the anal fin base. The number of principal dorsal fin rays is 10. There are 11 dorsal fin pterygiophores. The total number of vertebrae is 35, with 18 caudal vertebrae. The number of ribs is 15. In KMNH VP 100,179, the body depth is contained 2.1 times in the standard length. The head length is contained 3.2 times in the standard length. The dorsal fin base is contained 1.9 times in the anal fin base. The number of principal dorsal fin rays is 11. Nine pectoral fin rays is visible. The total number ofvertebrae is 35, with 18 caudal vertebrae. The number of ribs is 15. In KMNH VP 100,180, the body depth is contained 2.2 times in the standard length. The head length is contained 3.7 times in the standard length. The first dorsal pterygiophore is above the second caudal vertebra. The dorsal fin base is contained 1.9 times in the anal fin base. The number of principal dorsal fin rays is 11. There are 11 dorsal fin pterygiophores. The number of principal anal fin rays is 18. There are 18 anal fin pterygiophores. In KMNH VP 100,181, the body depth is contained 2.1 times in the standard length. The head length is contained 3.4 times in the standard length. The dorsal fin base is contained 1.7 times in the anal fin base. The number of principal dorsal fin rays is 10. The number of principal anal fin rays is 20. There are 20 anal fin pterygiophores. The number of ribs is 15. In KMNH VP 100,182, the body depth is contained 2.7 times in the standard length. The head length is contained 3.4 times in the standard length. The dorsal fin base is contained 2.1 times in the anal fin base. There are 11 dorsal fin pterygiophores. The number of principal anal fin rays is 19. There are 19 anal fin pterygiophores. Seven large canine like teeth are preserved at the posterior part of the orbit on the parasphenoid. The total number of vertebrae is 35, with 18 caudal vertebrae. The number of ribs is 15. Remarks. Aokiichthys uyenoi is close to Yungkangichthys hsitanensis Chang & Chou, 1974 in having almost same number of dorsal and anal fin rays and almost same proportion (Tab. 3). But it differs from Y. hsitanensis in having the smaller number of
EarlyCretaceous Freshwater Fish Fauna in Kyushu, Japan 173 vertebrae. The number of vertebra is 34 to 35 in A. uyenoi, 44 in Y. hsitanensis. A. uyenoi is closest to Aokiichthys otai in having almost same meristic characters and almost same proportion with the exception of the relative position of the median fins (Tab. 3). The origin of the dorsal fin is vertical with the fourth anal fin pteryg iophorein A. uyenoi. The originofdorsal fin is vertical with the anal origin in A. otai. Aokiichthys praedorsalis sp. nov. (Figs. 48-50, pis. 48-49) Diagnosis. It differs from other species of the genus Aokiichthys in having the combination of following characters. The dorsal fin is large. The anal origin is behind the dorsal origin and about vertical with the 7th dorsal fin pterygiophore (the middle of the dorsal fin base). The length of dorsal fin base is contained 1.2 times in the length of anal fin base. The number of dorsal fin rays is 11 to 13. The number of anal fin rays is 15 to 17. The parasphenoid teeth are larger than those of the premaxilla and the dentary. The length of lower jaw is contained 1.5 times in the head length. The known size is 57.7 to 146.7 mm. Holotype. KMNH VP 100,155, an almost complete specimen, but a dorsal part of caudal peduncle is missing. The head and caudal skeletons are poorly preserved. The standard length is 146.7 mm. Paratypes. KMNH VP 100,156, an anterior part of the body. The length from the anterior end of the premaxilla to the posterior end of the 20th vertebra is 82 mm. KMNH VP 100,157, an almost complete specimen with its right side exposed. The standard length is 61.8 mm. KMNH VP 100,158, an almost complete specimen, with its left side exposed. The standard length is 57.7 mm. Locality. Tokuriki (TO-1), Kokura-minami-ku (Kokura Southern Ward), Kitakyu shu City, Fukuoka Prefecture, Japan. Horizon. The First Formation (the lower formation, Wj, correlated to the Sengoku Formation) of the Wakino Subgroup in the Kwanmon Group, the Lower Cretaceous. Etymology: The species name, praedorsalis, means anterior position of the dorsal fin, which refers to the fact that the dorsal origin is situated before the anal fin in this species. Description of the holotype. The body is deep. The body depth is contained 2.8 times in the standard
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Early Cretaceous Freshwater Fish Fauna in Kyushu, Japan

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