Early Cretaceous Freshwater Fish Fauna in Kyushu, Japan

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180 Yoshitaka Yabumoto from Upper Jurassic to Recent in Africa, America, East Indies, Australia and Asia. Among them, most of Mesozoic genera (excepting Chandlerichthys from Middle Cretaceous deposits of North America by Grande, 1986) are known from Upper Jurassic to Lower Cretaceous time in eastern Asia. These are Lycoptera, Asiatolepis, Paralycoptera, Yanbiania, Yungkangichthys, Tongxinichthys, Plesiolycoptera, and Kuyangichthys (Takai, 1943; Liu H.-T. et al., 1963; Chang and Chou, 1974, 1976, 1977, 1986; Ma, 1980; Liu H.-T. etal., 1982; Li, 1987). Among these Mesozoicgenera, Wakinoichthys is closer to Lycoptera of the family Lycopteridae in having a slender body, the posterior position of the median fins, a series of leaf-shape supraneurals, and especially its caudal skeleton with seven hypurals, two parts of the first ural centrum, and the complete neural arch and spine of the first preural centrum which were described by Greenwood (1970). But Wakinoichthys differs from Lycoptera in having the following characters. There are no large teeth on the parasphenoid. The dorsal origin is behind the anal origin. The dorsal fin base is about half of the long anal fin base. The pectoral fin elongates. The centra are well ossified. In the caudal skeleton, Wakinoichthys is similar to the hiodontid genus Eohiodon from Eocene deposits ofNorth America (Cavender, 1966; Grande, 1979; Wilson, 1978) and Hiodon of Recent in North America, but differs in having no large teeth on the parasphenoid and the long pectoral fin. The long pectoral fin of Wakinoichthys is similar to that oftheosteoglossoid Singida from ?Paleocene of East Africa (Greenwood and Patterson, 1967), Phareodus from Eocene of North America (Cope, 1883; Grande, 1980) and the extant genera (Osteoglossum in South America and Scleropages in northern Australia and Southeast Asia). But these osteoglossoid genera differ from Wakinoichthys with their caudal skeleton. There are five hypurals in Singida and six hypurals in Phareodus, Scleropages and Osteoglossum (hypurals 3 to6 fused in Osteoglossum) and no uroneurals in Phareodus, Scleropages and Osteoglossum. The first ural centrum is not separated in these osteog lossoid genera (Greenwood, 1967; Greenwood and Patterson, 1967). Wakinoichthys is similar to two genera ofthe family Huashiidae, Huashia from Late Jurassic-Early Cretaceous deposits ofZhejiang Province in China (Chang and Chou, 1974, 1977) and Kuntulunia from Early Cretaceous deposits of Nei Mongol and Nigxia Province in China (Liu et al, 1982, 1985; Zhang, 1990), in the position ofmedian fins, having no large teeth on the parasphenoid and wide supraneurals, but differs in having the slender body, the long pectoral fin, the long and narrow frontals, the large gape of the mouth, seven hypurals, two parts of the first ural centrum and the uroneural not reaching to the second preural centrum. Chang and Chou (1977, 1986) considered that Huashia is related to the Chanidae. Liu et al (1985) and Zhang (1990) referred the Huashiidae to Osteoglossiformes. The caudal skeleton of Wakinoichthys indicates that the genus is closely related to those of the hiodontoid families Lycopteridae and Hiodontidae, which are included within the suborder Notopteroidei, but Wakinoichthys differs from them in having no
Early Cretaceous Freshwater Fish Fauna in Kyushu, Japan 181 large teeth on the parasphenoid. Genera of Notopteridae of the other superfamily (Notopteroidea) differs from Wakinoichthys in having a long anal fin confluent with a reduced caudal fin. Wakinoichthys aokii sp. nov. (Figs. 52-59, Pis. 50-51) Diagnosis. It differs from other species in having the combination of following characters. The estimated range of size is 70 to 120mm in standard length (The estimated maximum standard length is 120mm in the paratype, KMNH VP 100,143.). The body depth is contained 6.4 times in the standard length. The head length is contained 4.4 times in the standard length. The dorsal origin is about vertical with the anterior one fourth of the anal base. The number of principal dorsal fin rays is 10 to 12. There are 10 to 12 dorsal fin pterygiophores and a stay. The number of principal anal fin rays is 20 to 22. There are 19 to 21 anal fin pterygiophores. The total number of vertebrae is 45 to 49, with 24 to 25 caudal vertebrae. The number of ribs is 22 to 23. Holotype. KMNH VP 100,140, a nearly complete specimen from the Fourth Formation. The pelvic fin is missing. The standard length is 70.4mm. Paratypes from the Fourth Formation. KMNH VP 100,141, a nearly complete specimen. The standard length is 104.8 mm. KMNH VP 100,142, a specimen missing the head region. The length from the pectoral insertion to the posteriorend of the hypural is 69.5 mm. KMNH VP 100,143, a specimen missing the anterior part of the head region. The length from the pectoral insertion to the posterior end of the hypural is 85.5 mm. Paratypes from the Third Formation at Minamigaoka (KM-1). KMNH VP 100,184, an almost complete specimen, with its right side exposed, but the upper lob ofcaudal fin and the anterior end of the dentaryare missing. The standard lengthis 59.7mm. KMNH VP 100,185, an almost complete specimen with its right side exposed, but the anterior part of the head is missing. The length between the pectoral insertion and the end of the hypural is 41.0 mm. KMNH VP 100,186, a specimen with its left side exposed. The posterior part of the caudal bones is missing. The body slightly bents at the middle. The length from the snout to the posterior margin of the first preural centrum is 66.0 mm. KMNH VP 100,187, an almost complete specimen with its right side exposed, but the body strongly bents and the part from the posterior dorsal fin base to the posterior anal fin base is missing. Locality. Kumagai (KA-0, KD-34) and Minamigaoka (KM-1), Kokura-kita-ku (Kokura Northern Ward), Kitakyushu City, Fukuoka Prefecture, Japan.
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Early Cretaceous Freshwater Fish Fauna in Kyushu, Japan

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