The Larvae of Eurycea bislineata major

Abstract

YW E have recently had opportunity to examine a series of 88 specimens, mostly larvae, of Eurycea bislineata major Trapido and Clausen, taken in the Laurentides National Park, Quebec, during the summer of 1938. We named this subspecies on the basis of adult material (1938), and we can now point out the larval characters which differentiate Eurycea bislineata major from bislineata. The comparisons with and distinctions from the latter are based on material from the vicinity of Ithaca, New York. We are grateful to Mr. Richard Bernard for acquainting us with the E. b. major material, and indebted to Dr. V. D. Vladykov, Director of the Biological Station of the Laurentides National Park, for the opportunity to examine the specimens collected by him and his colleagues, and to Miss Octavia Bailey for her painstaking drawings illustrating the larvae. Oliver and Bailey (1939) have suggested that the characters used to distinguish major are insufficient for the adequate definition of a nomenclatorially recognizable race. Since we consider subspecies to be variations geographically correlated and hence worthy of recognition, E. b. major still impresses us as significant and taxonomically valid. Although the characters of the adults represent developments correlated with extreme size, this tendency toward largeness, with associated characters, has yet to be duplicated generally by another regional population. The larvae of E. b. major of all sizes from 15 mm. to 70 mm. differ strikingly from those of E. b. bislineata in coloration. E. b. major is much darker than E. b. bislineata, as reference to the accompanying drawings will show. Of more significance, perhaps, than this mere intensification of the coloration, are the differences in pattern. In E. b. bislineata (fig. 1, A) the color pattern of the sides continues across the back, only interrupted by the series of dorso-lateral light spots; in E. b. major these dorso-lateral light spots border a relatively light band down the back (fig. 1, B). Individuals of E. b. bislineata approaching transformation and adult coloration have the back lighter than the sides, but the light dorsal band mentioned above is found in E. b. major of all sizes, even newly hatched specimens of 15 or 16 mm. The clear throat region of E. b. major is marked by the encroachment on each side of a semicircle of the dark dorsal pigmentation (fig. 1, D): in E. b. bislineata there is seldom even any indication of ventro-lateral pigmentation in the throat region (fig. 1, C). Three or four of the largest E. b. major (68-70 mm.) show a marked development of dark ventral coloration on the body (fig. 1, D). We have never seen E. b. bislineata with other than a clear venter. The darkening of the belly apparently occurs in only the oldest of E. b. major larvae. The shape of the fin fold perhaps affords the most significant difference. E. b. major has the fin rising more abruptly at the base of the tail, and more truncate at the end, as well as higher over its entire length (fig. 1, E), than in E. b. bislineata.