Early Cretaceous Freshwater Fish Fauna in Kyushu, Japan

Early Cretaceous Freshwater Fish Fauna in Kyushu, Japan 191
combination of following characters. The body depth is contained 3.5 to 3.8 times in
the standard length. The head length is contained 3.2 to 3.9 times in the standard
length. The number of vertebrae is 45 to 47, with 22 caudal vertebrae. The
number of ribs is 19 to 23.
Holotype. KMNH VP 100,188, an almost complete specimen, with its right side
exposed, but the middle of the body is slightly moved. The standard length is 38.6
Paratypes. KMNH VP 100,189, an almost complete specimen, with its left side
exposed, but the anterior part of mandible is missing. The standard length is 31.8
mm. KMNH VP 100,190,an almost complete specimen, with its right side exposed,
but the anterior end of the head region and the posterior part of the body are missing.
The body bents at the middle. The length from the pectoral insertion to the anal
origin is 13.8mm. KMNH VP 100,191, a specimen with its right side exposed.
The head and the anterior part of the abdomen are missing. The body bents at the
middle. The length from the anal origin to the end of the hypural is 16.2 mm.
Locality. Minamigaoka (KM-1), Kokura-kita-ku (Kokura Northern Ward), Kita
kyushu City, Fukuoka Prefecture, Japan.
Horizon. The Third Formation (the upper formation, W3, correlated to the Lower
Wakamiya Formation) of the Wakino Subgroup in the Kwanmon Group, the Lower
Cretaceous.
Etymology. The species name, robustus, means strong or robust, which refers to the
fact that the body depth of this species deeper than that of W. aokii.
Description of the holotype.
The body is moderate. The body depth is contained 3.8 times in the standard
length. The head length is contained 3.9 times in the standard length. The outline
of the head dorsal margin is slightly convex. The outline from the occipital region to
the dorsal origin is slightly convex (Fig. 60). The restored outline of the abdomen is
slightly convex (Fig. 61). Median fins are relatively posterior in position. The
dorsal origin is behind the anal origin and about vertical with the 13th anal fin
pterygiophore (the anterior two-thirds of the anal fin base). The first dorsal
pterygiophore is inserted between the 5th and the 6th caudal vertebrae. The dorsal
fin base is contained 2.8 times in the anal fin base. The pectoral fin is long and
reaches the pelvic insertion. The caudal fin is forked. The number of principal
dorsal fin rays is 10. There are 11 dorsal fin pterygiophores. The number of
principal anal fin rays is 20. There are 19 anal fin pterygiophores. Ten pectoral fin