Early Cretaceous Freshwater Fish Fauna in Kyushu, Japan

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jgg Yoshitaka Yabumoto The coracoid is low and round at the posterior margin. The posterior end of the lower jaw is placed almost below the posterior margin of the orbit. The parasphe noid tooth is not visible. There are villiform teeth on the endopterygoid. The palatine is slender and has minute teeth. The total number of vertebrae is 35, with 19 caudal vertebrae. The anterior end of the vertebral column is not visible. The number ofabdominal vertebrae is estimated on the basis of the ribs. The number of ribs is 14. There is a series of median supraneurals behind the head and ending above the first caudal vertebra. Each supraneural from the first to the third is leaf-shape with a ridge running from a dorsal end to a ventral end. The other supraneurals are cylindrical. The first preural centrum bears the narrow parhypural. The neural arch and spine of the first preural centrum are separated each other. Five hypurals are visible. The first hypural is the largest. The second hypural is about one fifth of the first one in width. There is a space between the second and third hypurals. The second to fifth hypurals are slender. There are two ural centra. The second ural centrum bears at least three hypurals (HYU3-5). Three uroneurals are visible. The epural is not visible (Fig. 43). The first uroneural extends forward to the first ural centrum. Description of the paratypes. In KMNH VP 100,174, the body depth is contained 2.1 times in the standard length. The head length is contained 3.7 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 12. There are 12 dorsal fin pterygiophores. The number of principal anal fin rays is 19. The dentary bears small canine like teeth on its oral margin. The suture between the dentary and anglo-articular is not visible. Three large canine like teeth are visible on the parasphenoid at the posterior part of orbit. The total number of vertebrae is 36, with 19 caudal vertebrae. In KMNH VP 100,175, the body depth is contained 2.4 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. The number of principal anal fin rays is 19. There are 20 anal fin pterygiophores. The total number of vertebrae is 34, with 18 caudal vertebrae. The number of ribs is 14. Remarks. This new species, Aokiichthys otai, resemble Yungkangichthys hsitanensis Chang & Chou, 1974 (Fig. 29) 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 thesmaller numbers ofvertebrae. The number ofvertebrae is 34 to 36in A. otai, 44 in Y. hsitanensis. A. otai is closest to Aokiichthys uyenoi in having almost same meristic character and the proportion with the exception of the relative position of the median fins (Tab. 3). The origin of dorsal fin is vertical with the anal origin in A.
Early Cretaceous Freshwater Fish Fauna in Kyushu, Japan 167 otai. The origin of dorsal fin is vertical with the fourth anal fin pterygiophore in A. uyenoi. Aokiichthys uyenoi sp. nov. (Figs. 44-47, PI. 47) Diagnosis. It differs from other species of the genus Aokiichthys in having the combination of following characters. Large teeth are present on the parasphenoid. The body is deep and the body depth is contained 2.1 to 2.5 times in the standard length. The median fins are relatively posterior in position. The dorsal origin is behind the anal origin and is vertical with the fourth anal fin pterygiophore. The number of principal dorsal fin rays is 9 to 11. The number of principal anal fin rays is 18 to 21. The range of size is 46.3 to 69.4 mm in standard length. The number ofvertebrae is 34 to 35 with, 17 to 18 caudal vertebrae. The number of ribs is 14 to 15. Holotype. exposed. KMNH VP 100,176, an almost complete specimen with its right side The standard length is 56.2 mm. Paratypes. KMNH VP 100,177, an almost complete specimen with its right side exposed, with the counter part of the anterior part of the body, but the central part of the caudal skeleton is missing. The standard length is 59.4 mm. KMNH VP 100,178, an almost completespecimen with its leftside exposed, but the caudal fin is missing. The standard length is 69.4 mm. KMNH VP 100,179, an almost com plete specimen with its right side exposed. The standard length is 53.3 mm. KMNH VP 100,180, an almost complete specimen with its left sideexposed. The standard length is 61.9 mm. KMNH VP 100,181, an almost complete specimen with its right side exposed. The standard length is 46.3 mm. KMNH VP 100,182, an almost complete specimen with its left side exposed. The standard length is 65.5 mm. Etymology. The species is named for Dr. Teruya Uyeno, a ichthyologist who gave me many valuable advice for the present study and has contributed to the study of fish fossils in Japan. Locality. Tokuriki (TO-1), Kokura-minami-ku (Kokura Southern Ward), Kitakyu shu City, Fukuoka Prefecture, Japan. Horizon. The First Formation (the lower formation, W,, correlated to the Sengoku Formation) ofthe Wakino Subgroup in the Kwanmon Group, the Lower Cretaceous.
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Early Cretaceous Freshwater Fish Fauna in Kyushu, Japan

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