The “False Breeding Season” of the Eastern Newt, Notophthalmus viridescens

The terrestrial red eft stage is so different from the body form of the aquatic adult of the eastern newt that the two were considered separate species for nearly 60 years. Some populations lack the eft stage whereas in other populations the adults are aquatic only during the breeding season. In populations in which the adults are permanently aquatic or migrate to breeding ponds in fall, an autumnal mating season may occur, which has been termed the “false breeding season” because oviposition does not occur until the spring mating season. However, this period is not “false” but rather the early portion of an extended mating season made possible by female sperm storage. The eastern newt, Notophthalmus viridescens, is one of the most widely distributed salamanders in North America, and can be found from eastern Texas northward to Canada and then eastward to the Atlantic coast (Petranka, 1998). Four subspecies are recognized. A great deal of literature exists on the life history of the eastern newt, but most of it concerns the northeastern form, the red-spotted newt, N. v. viridescens. Much of this interest was sparked by the discovery that many populations have pond-dwelling, aquatic adults and larvae, but the larvae metamorphose into an immature “red eft” stage that leaves the water and assumes a terrestrial existence for anywhere from one (Gibbons and Semlitsch, 1991) to seven (Healy, 1974) years. Red efts, especially younger ones, can be bright vermilion and have granular skin, but as efts reach maturity, the morphology changes once again as the animals migrate back to aquatic, generally lentic habitats (Petranka, 1998). The adult animals are a shade of green dorsally, and have compressed tails. In N. v. viridescens, both the eft and the adult have a lateral row of red spots bordered by black, resulting in the traditional common name. In the other subspecies, the red spots are either absent (central newt, N. v. louisianensis and the Florida peninsula newt, N. v. piaropicola) or form a series of broken lines (broken-striped newt, N. v. dorsalis). Aquatic adult males develop especially prominent tail fins during the breeding season. The aquatic adult and the terrestrial eft are so different that the original descriptions by Rafinesque (1820) placed them in different subgenera, and the controversy over whether they represented different species or not was not definitely settled until Cope (1889). The existence of a terrestrial stage and an aquatic stage is not just limited to Notophthalmus viridescens, but is generally characteristic of all salamanders within the Salamandridae referred to as “newts” (including other species in the genus Notophthalmus and those in the genera Cynops, Taricha, Triturus plus some more obscure taxa), and is the reason for separating out these species by this common designation from other salamanders. Within Notophthalmus viridescens, however, some populations contain paedomorphic individuals, which do not fully metamorphose (i.e. , larval gills are retained) and which may spend their entire life in a permanent pond (Noble, 1926, 1929; Brandon and Beemer, 1966; Healy, 1974; Reilly, 1986, 1987). I became interested in variation in the life history of Notophthalmus viridescens when studying female sperm storage in a population of red-spotted newts on the Department of Energy’s Savannah River site, near Aiken, South Carolina (Sever et al. , 1996). In the pond inhabited by the newts we studied, mating took place from December into April, and females, which do indeed store sperm in cloacal spermathecae, kept laying eggs through May. Then something remarkable happened: all of the newts vanished from the pond, not to be seen in the water again until the following October. Thus, the adult “aquatic” stage was not a permanent condition; even the adults in this population had a terrestrial phase. I wanted to see how widespread this condition was in the literature, but the more I delved into past studies, the more I was impressed with just how much variability exists. The literature is quite extensive, but serious gaps exist in our knowledge of life histories of eastern newts, especially western and southern populations. Studies on the northern red-spotted newt, however, date back into the nineteenth century. One aspect of the life history of the red-spotted newt that has come under much scrutiny is the timing of the breeding season, especially if an autumnal “false breeding season” exists. In this paper, I review some of the relevant literature dealing with the timing of the breeding season in Notophthalmus viridescens. I emphasize the older literature, which is not easily accessible. First, however, I shall review the nomenclatural history of the species, and the relationship of the taxonomy to discoveries about the life history of the red-spotted newt.