Siegel, D. S., H. R. Locke, M. E. Martinez, B. J. Schuessler, M. A. Kist, J. T. Gruber, K. M. Stemp, S. D. Trame & J. M. Davenport

The reproductive cycle of male Eastern Newts (Notophthalmus viridescens) from a high-elevation population in North Carolina, U.S.A. pp. 365-372.

Abstract. The reproductive cycle of male Notophthalmus viridescens from a high-elevation population in North Carolina, U.S.A., was outlined through histological examination of testes, sperm ducts, and secondary sexual characteristics (genial glands and collecting ducts of the kidneys). Similar to other populations of N. viridescens, proliferation of spermatogonia was a spring event with the meiotic stages of spermatogenesis restricted to the months of June through August (summer months). Spermiation immediately followed in September with sperm filling the Wolffian ducts. Spermiation continued until the following summer where mature sperm from the previous summer could still be found in cranial portions of testes while the more caudal portions of testes were undergoing meiosis to produce sperm for the subsequent season. This overlap of spermatogenic cycles was not observed in studies of N. viridescens from other populations. Sperm were found in Wolffian ducts until the following July, indicating potential for mating from September to July. Secretory granules filled epithelial cells of genial glands and kidney collecting ducts from September to July, providing support for this prolonged potential mating season. In other populations of N. viridescens, secondary sexual characteristics were atrophied for a longer window of time, at minimum July through August. In culmination, while the spermatogenic cycle of high-elevation North Carolina populations of N. viridescens was found to be similar to that of other populations, the mating season was potentially extended. Considering mating in N. viridescens was typically reported as a fall through spring event, the ecological factor most responsible for driving this extended mating window was potentially protracted exposure to cooler temperatures at higher elevations.

Key words. Amphibia, Caudata, newt, Salamandridae, testis, spermatogenesis, spermatozoa, mating.