Early Cretaceous Freshwater Fish Fauna in Kyushu, Japan

208 Yoshitaka Yabumoto
standard length. The restored outline of the abdomen is remarkably convex. The
head length is contained 3.6 to 3.7 times in the standard length. The angle between
the upper and lower limbs of the preopercle is right-angled. The depth between the
dorsal margin of the body and the abdominal vertebral column at the maximum
depth of the body is contained 3.3 times in the depth from the abdominal vertebral
column and the ventral margin of the body. The number of dorsal fin pteryg
iophores is 10 to 12. The number of anal fin pterygiophores is 23 to 24. The total
number of vertebrae is 34 to 36, with 16 caudal vertebrae. The number of ventral
scutes is 17 to 18 in total, with 10scutes between the pectoral and pelvic fins, and 7
to 8 scutes between the pelvic and anal fins. The number of supraneurals is 7.
Holotype. KMNH VP 100,217, an almost complete specimen, with its left side
exposed, but the posterior part of the caudal fin is missing. The standard length is
46.6 mm.
Paratypes. KMNH VP 100,218, an almost complete specimen, with its left side
exposed. The standard length is 36.8 mm. KMNH VP 100,219, an almost com
plete specimen, with its left side exposed. The length from the snout to the fifth
caudal vertebra is 32.2 mm. KMNH VP 100,220, an almost complete specimen,
with its left side exposed, but the dorsal fin, a part of the abdomen and the posterior
part of the caudal fin are missing. The standard length is 47.1 mm. KMNH VP
100,221, an almost complete specimen, with its left side exposed, but the anterior part
of the mandible and the posterior part of the anal fin are missing. The standard
length is 29.3 mm.
Locality. Kumagai (KD-34), Kokura-kita-ku (Kokura Northern Ward), Kitakyu
shu City, Fukuoka Prefecture, Japan.
Horizon. The Fourth Formation (the uppermost formation, W4, correlated of the
Upper Wakamiya Formation) of the Wakino Subgroup in the Kwanmon Group, the
Lower Cretaceous.
Etymology. The species name, altisomus, means deep body, which refers to the fact
that this species has the deepest body among the species of the genus from the
Wakino Subgroup.
Description of the holotype.
The body is deep and the body depth is contained 2.3 times in the standard
length. The head length is contained 3.7 times in the standard length. The snout
is round. The outline of the head dorsal margin is almost straight, but the restored
outline is slightly convex. The outline from the occipital region to the dorsal origin