Early Cretaceous Freshwater Fish Fauna in Kyushu, Japan

148 Yoshitaka Yabumoto
Table 3.
Comparison of the characters of the lycopterid species having 15 branched
Aokiichthys toriyamai
gen. et sp. nov.
A. changae
gen. et sp. nov.
A. otai
gen. et sp. nov.
A. uyenoi
gen. et sp. nov.
SL 34.8-74.9 mm 62.5-83.1 mm 55.3-60.2 mm 46.3-69.4 mm
counts
D. 9-12 9-11 11-12 9-11
A. 18-20 17-19 19 18-21
V.
35-36
(16--17+17-19)
35-36
(16-17+18-19)
34-36
(16-17+17-19)
34-35
(16-17 + 17-18)
ribs 14-15 14-15 14-15 14-15
ratio
SL/BD 3.0-3.7 3.2-3.7 2.1-2.4 2.1-2.5
AB/DB 1.6-2.1 1.6-2.2 1.8-1.9 1.7-2.3
D/=A* D=A A/D D=A A/D
A., anal fin rays; AB, anal fin base; BD, bodydepth; D., dorsal fin rays; DB,dorsal fin base; SL,
standard length; V., vertebrae.
* The position of the dorsal and anal origins. D/A, the dorsal origin is before the anal origin.
D=A, the dorsal origin is vertical with the anal origin. A/D, the dorsal origin is behind the
anal origin.
Jurassic to Lower Cretaceous time in eastern Asia. These are Lycoptera, Asiatolepis,
Paralycoptera, Yungkangichthys, Yanbiania, Tongxinichthys and Plesiolycoptera (Takai, 1943;
Liu H.-T. et al, 1963; Chang and Chou, 1974, 1976, 1977, 1986; Ma, 1980; Li,
1987). Among these Mesozoic genera, Aokiichthys is close to the genus Paralycoptera,
which has two species P. wui Chang & Chou, 1974 (Fig. 30) and P. changi Ma &
Sun, 1988, and the genus Yungkangichthys, which has only species Y. hsitanensis Chang
& Chou, 1974 (Fig. 29), from Early Cretaceous deposits of Zhejiang and Jilin
(Chang and Chou, 1974, 1977; Ma and Sun, 1988) in having 15 branched caudal fin
rays and thelarge teeth on theparasphenoid. These two genera belong to the family
Lycopteridae (Chang and Chou, 1974, 1977). But Aokiichthys differs from Paralyco
ptera and Yungkangichthys with the smaller number of vertebrae and ribs. The
number of vertebrae is 34 to 36 with 17 to 19 caudal vertebrae in Aokiichthys, 40 to 42
with 20 caudal vertebrae in Paralycoptera, 44 with 22 caudal vertebrae in Yungkangich
thys. The number of ribs is 14 to 15 in Aokiichthys, 20 to 22 in Paralycoptera, 16 in
Yungkangichthys. (Tab. 3).
The number of vertebrae (34 to 36) is the fewest in the Osteoglossomorpha.
Greenwood (1970) listed lycopterid species with as few as forty. Kipalaichthys
sekirskyi has 38 to 40 vertebrae (Casier, 1965; Taverne, 1979).