Willey 1 has recently referred to the absence of the ventral fins in a mate specimen of Amia calva and urges the necessity of recording such observations as they are likely to throw some light on «natural mutations amongst fishes.» In the course of my studies on the freshwater fishes of India, I have come across a few «mutations» of this nature and I take this opportunity of bringing them to notice.
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I will now briefly deal with the two Indian genera of freshwater fishes that are distinguished from their nearest relatives by the absence of the ventral fins. These are Channa, Gronow and Apua, Blyth. The genus Channa, which was hitherto known from Ceylon, the Philippines, China and Japan, has recently been recorded from Burma by Chaudhuri.2 According to both Günther 3 and Day 4 this genus is distinguished from Ophiocephalus, Bloch by the absence of the ventral fins and the pyloric or coecal appendages. In the original description of the genus by Gronovius 5 the only significant phrase is « Ventrales nullae». I have examined two species of Channa, one described by Chaudhuri (op. cit.) and the other contained in Dr. N. Annandale's Chinese collection. In both these species pyloric appendages similar to those of Ophiocephalus are present. The only character, therefore, that distinguishes Channa from Ophiocephalus is the absence of the ventral fins. The occasional absence of the ventrals has been regarded in other genera as an abnormality or a case of genital variation; but in Channa this character seems to have become permanent, for large series of specimens with the ventrals absent have been collected from the same locality. Moreover, no species of Channa has been described having the same specific characters as any known species of Ophiocephalus. Some people attribute the absence of the ventrals to the habits of these fishes, but how far this is true I have no evidence to judge at present.
It is otherwise in the case of the second genus, Apua which was described from two specimens and has not been recorded since. Vinciguerra 6 doubted the existence of Apua and referred his specimens to Acanthophtalmus from which Blyth's genus is distinguished chiefly by the absence of the ventral fins. I have carefully examined the two unique type-specimens preserved in the Indian Museum and a large series of fresh specimens of Acanthophtalmus pangia from Manipur. I do not find any trace of the ventrals or of accidental injury in the former. Moreover, I cannot distinguish Blyth's specimen from Acanthophtalmus pangia except by the absence of the ventrals. I am, therefore, led to believe that the specimens of Apua were abnormal and that the genus Apua cannot stand distinct from Acanthophtalmus.
I conclude, therefore, that the cases of Apua and Channa are not to be considered parallel. Channa has been found by numerous collectors at many different places over a very wide area and the ventrals are invariably absent. Apua on the other hand, has only once been collected and only two individuals were then found.
I have carefully dissected a specimen of Channa burmanica Chaudhuri, and have not been able to find any trace of the pelvic girdle.
1 Willey, Proc. Zool. Soc. London, pp. 89-90 (1920). Back
2 Chaudhuri, Rec. Ind. Mus. XVI, p. 784 (1919) . Back
3 Günther, Cat. Brit. Mus. Fishes III, p.468 and 483. Back
4 Day, Fishes of India II, p.356. Back
5 Catalogue of fish in the British Museum, p.99 (1854). The above citation is a republishing. This is the original text passage [snakeheads.org] Back
6 Vinciguerra, Ann. Mus. Civ. Stor. Nat. Genova, XXIX, pp. 348-349 (1889). Back
These passages were originally published 1921 under the above title in: Records of the Indian Museum, vol. 22 no.1, pp. 27-33.
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