Early Cretaceous Freshwater Fish Fauna in Kyushu, Japan

40-42
2.9
Early Cretaceous Freshwater Fish Fauna in Kyushu, Japan 137
Table 2.
Comparison of characters in the speciesof the family Chuhsiungichthyiidae nov.
Chuhsiungichthysyanagidai
sp. nov.
C.japonicus sp. nov. C. tsanglingensis Mesoclupea shoivchangensis
SL 168.2 mm 217.0-220.0 imm 50-140 mm 40-170 mm
counts
D. 20-21 21 21-23 14
A. 32 39 39-40 46
P. 14+ 18 15 12
Vertebrae 40 —
ratio
53-54
SL/BD 3.6 2.4-2.5 3.0-3.7 2.7-3.4
SL/HL 4 —
3.8
AB/DB 1.4 1.6 1.9 4.2
A., anal fin rays; AB, anal fin base; BD, body depth; D., dorsal fin rays; DB, dorsl fin base; HL,
head length; P|, pectoral fin rays; SL, standard length.
Remarks. Although the present fossils are poorly preserved in head region, it
clearly shows a character to be a member of the order Ichthyodectiformes by the
uroneurals covering the lateral surfaces of the preural centra (Fig. 21). The
Ichthyodectiformes contains 13 or 14 genera from Upper Jurassic to Lower Cre
taceous deposits of all continents in the world (Patterson and Rosen, 1977).
Among them, the present new species is considered to belong to the genus Chuhsiung
ichthys from Upper Cretaceous of Yunnan Province (Lew, 1974) because this species
is closest to Chuhsiungichthys tsanglingensis Lew, 1974 (Fig. 22) in the proportion and
meristic characters with the exception of number of anal fin rays (D. 21-23; A. 39-
40; V. 40-42 in C. tsanglingensis) (Tab. 2). This species differs from Mesoclupea,
which has a single species M. shoivchangensis Ping & Yen, 1933 (Fig. 23), from Late
Jurassic of Zhejiang Province and Chekiang Province (Ping and Yen, 1933; Chang,
1963;Chang and Chou, 1974, 1977; Chang and Chow, 1986) in the position and the
size of the dorsal fin (the dorsal fin is small and the dorsal base is situated above the
middle of anal fin base in Mesoclupea) and the meristic characters (D. 14; A. 46; V.
53-54 in Mesoclupea and D. 20-21; A. 32; V. 40 in this species). Chuhsiungichthys
yanagidai differs from Chuhsiungichthysjaponicus with more slender body (the body depth
is contained 2.4 to 2.5 times in the standard length in C.japonicus) and in the number
of anal fin rays (Tab. 2).
Chuhsiungichthys japonicus sp. nov.
(Figs. 24-25, PI. 41)
Diagnosis. This species differs from other species of the genus Chuhsiungichthys in
having the combinationof following characters. The dorsal fin is large. The dorsal