Abstract
(1) The characteristics of pharyngeal bones and their teeth in two genera and seven species of Japanese Acheilognathid fishes are described in this paper.
(2) The characteristics of the pharyngeal bones and their teeth in Acheilognathid fishes, as a whole, are summarized as follows: Pharyngeals with prominent anterior angle, breadth 2.5-3.0 in length, length 10-13 in body length of the fish. Teeth only one-rowed, 5, 0, 0-0, 0, 5 in dental formula, moderately compressed, laterally symmetrical, with well developed long and narrow grinding surface. Tips of teeth smoothly, weakly recurved and more or less expanded, with pointed ends.
(3) As a substitute for conclusion, the writers have established the following key according to the characters of them, for conveniences in identification.
A1 Side of pharyngeal teeth without serrations
B1 Length of bone about 12.1-13.0 in body length, breadth of bone 2.75 in length, anterior and posterior edentulous processes equal in breadth……Rhodeus ocellatus (KNER)
B2 Length of bone about 11.1-12.0 in body length, breadth of bone less than 2.75 in length, anterior edentulous process broader than posterior one.
C1 First tooth with grinding surface, breadth of pitted surface of anterior edentulous process about 1/2 in breadth of the process, breadth of pitted surface of bone above 80% in breadth of the bone…… Acheilognathus lanceolata (TEMMINCK et SCHLEGEL)
C2 Grinding surface of first tooth degenerative, breadth of pitted surface of anterior edentulous process less than 1/3 in breadth of the process, breadth of pitted surface of bone about 76% in breadth of the bone…… Acheilognathus limbata (TEMMINCK et SCHLEGEL)
A2 Side of pharyngeal teeth with serrations
D1 Pitted surface reaching to middle region of anterior limb……
Acheilognathus longipinnis REGAN
D2 Pitted surface reaching to near top of anterior limb
E1 Breadth of bone less than 2.6 in length, length of bone above 13 in body length…… Acheilognathus cyanostigma JORDAN et FOWER
E2 Breadth of bone above 2.6 in length, length of bone less than 13 in body length
F1 Length of bone 10-11 in body length, groove of anterior margin of grinding surface reaching to central region of the grinding surface, anterior and posterior edentulous processes equal in length……Acheilognathus rhombea (TEMMINCK et SCHLEGEL)
F2 Length of bone about 12 in body length, groove of anterior margin of grinding surface not reaching to central region of the grinding surface, anterior edentulous process longer than posterior one…… Acheilognathus tabira JORDAN et THOMPSON
