Of the Eastern Newt, Notophthalmus Viridescens David M

Of the Eastern Newt, Notophthalmus Viridescens David M

Bull. Chicago Herp. Soc. 41(8):149-153, 2006 The “False Breeding Season” of the Eastern Newt, Notophthalmus viridescens David M. Sever Department of Biological Sciences Southeastern Louisiana University Hammond, LA 70402 Abstract 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 I became interested in variation in the life history of most widely distributed salamanders in North America, and can Notophthalmus viridescens when studying female sperm storage be found from eastern Texas northward to Canada and then in a population of red-spotted newts on the Department of eastward to the Atlantic coast (Petranka, 1998). Four subspe- Energy’s Savannah River site, near Aiken, South Carolina cies are recognized. A great deal of literature exists on the life (Sever et al., 1996). In the pond inhabited by the newts we history of the eastern newt, but most of it concerns the north- studied, mating took place from December into April, and eastern form, the red-spotted newt, N. v. viridescens. Much of females, which do indeed store sperm in cloacal spermathecae, this interest was sparked by the discovery that many popula- kept laying eggs through May. Then something remarkable tions have pond-dwelling, aquatic adults and larvae, but the happened: all of the newts vanished from the pond, not to be larvae metamorphose into an immature “red eft” stage that seen in the water again until the following October. Thus, the leaves the water and assumes a terrestrial existence for any- adult “aquatic” stage was not a permanent condition; even the where from one (Gibbons and Semlitsch, 1991) to seven adults in this population had a terrestrial phase. (Healy, 1974) years. Red efts, especially younger ones, can be I wanted to see how widespread this condition was in the bright vermilion and have granular skin, but as efts reach literature, but the more I delved into past studies, the more I maturity, the morphology changes once again as the animals was impressed with just how much variability exists. The migrate back to aquatic, generally lentic habitats (Petranka, literature is quite extensive, but serious gaps exist in our 1998). The adult animals are a shade of green dorsally, and knowledge of life histories of eastern newts, especially western have compressed tails. In N. v. viridescens, both the eft and and southern populations. Studies on the northern red-spotted the adult have a lateral row of red spots bordered by black, newt, however, date back into the nineteenth century. One resulting in the traditional common name. In the other sub- aspect of the life history of the red-spotted newt that has come species, the red spots are either absent (central newt, N. v. under much scrutiny is the timing of the breeding season, louisianensis and the Florida peninsula newt, N. v. piaropicola) especially if an autumnal “false breeding season” exists. In or form a series of broken lines (broken-striped newt, N. v. this paper, I review some of the relevant literature dealing with dorsalis). Aquatic adult males develop especially prominent the timing of the breeding season in Notophthalmus viridescens. tail fins during the breeding season. The aquatic adult and the I emphasize the older literature, which is not easily accessible. terrestrial eft are so different that the original descriptions by First, however, I shall review the nomenclatural history of the Rafinesque (1820) placed them in different subgenera, and the species, and the relationship of the taxonomy to discoveries controversy over whether they represented different species or about the life history of the red-spotted newt. not was not definitely settled until Cope (1889). The existence of a terrestrial stage and an aquatic stage is Taxonomic History not just limited to Notophthalmus viridescens, but is generally The eastern newt was first described by the great American characteristic of all salamanders within the Salamandridae naturalist Constantine Samuel Rafinesque (Rafinesque, 1820). referred to as “newts” (including other species in the genus As mentioned previously, he placed the adult form and the red Notophthalmus and those in the genera Cynops, Taricha, Tri- eft in different subgenera; the genus he choose for both was turus plus some more obscure taxa), and is the reason for Triturus, a genus Rafinesque described in 1815 that contains separating out these species by this common designation from the European newts. The adult form, with a type locality of other salamanders. Within Notophthalmus viridescens, how- “Lake George, Lake Champlain” in New York, was designated ever, some populations contain paedomorphic individuals, Triturus (Diemictylus) viridescens (vulgar name, “Green which do not fully metamorphose (i.e., larval gills are retained) Ebbet”), and the eft, with no type locality except in the broad- and which may spend their entire life in a permanent pond est terms (“states of New York, New Jersey, Connecticut, (Noble, 1926, 1929; Brandon and Beemer, 1966; Healy, 1974; Vermont, etc.”), was named Triturus (Notophthalmus) miniatus Reilly, 1986, 1987). 149 (“Red Ebbet”). 1962 that because Baird (1850) first referred viridescens to Notophthalmus rather than Diemictylus, that Notophthalmus Spencer Fullerton Baird, founder of the herpetological had preference under the rule of first revisor (ICZN, 1962). collections at the Smithsonian Institution, removed the two forms from Triturus, although he kept them as different spe- Variation in Life History cies. Baird (1850) noted, however, “Thus, of the highly natu- ral genus Notophthalmus (Diemyctylus) one species (Diemycty- The first review of the life-history of the red-spotted newt lus viridescens) is the most aquatic of all American forms, the was by Gage (1891). He opened his paper by stating: “The other (D. miniatus) the most terrestrial; yet the two are so working out of the complete life-history of this newt has extend- much alike in shape as to render it a matter of some difficulty ed from 1819SQ 1820, when Say and Rafinesque first considered to distinguish them.” Note that Baird seemingly considered the it, until the present year. During this period of seventy- genera Notophthalmus and Diemictylus interchangeable, but he two years it has been the subject of numerous investigations; mentioned Notophthalmus first, which gave that name priority. but from the striking changes in coloration, habit, and structure Also, Baird (1850) misspelled Diemictylus, and this mistake passed through in its various stages of development it has was perpetuated for the rest of the nineteenth century. proved unusually puzzling to the naturalist and physiologist.” Edward Hallowell, a Philadelphia physician best known for Gage (1891) established that fertilization in Notophthalmus his work on reptiles, expressed even stronger doubts about viridescens was internal, by isolating four females from New separation of the forms into different species. He stated York from any males. All laid fertile eggs. Gage believed that (Hallowell, 1856), “Diemyctylus viridescens and D. miniatus only 6SQ 7 eggs can be laid before a female requires an additional are probably the same, the orange color and roughness being mating. In New York, the mating/oviposition period was appearances which, the female more especially, presents after a AprilSQ June. Gage, however, noted that specimens from au- long sojourn on land. At least this may be inferred from the tumn appeared to be in breeding condition, and if “the two known habits of European Tritons.” sexes are placed together a typical mating will occur, and the emission of spermatophores will occur exactly as described for The noted American herpetologist and paleontologist Ed- the spring, or proper breeding season. It is not easy to ward Drinker Cope commented on the eastern newt in 1859 in understand the purpose of this autumnal mating, as no eggs his first publication, written at the age of 18. Cope (1859) were ever found in the oviducts in autumn, and it is not known wrote, “We include in the above synonyms (of Diemyctylus whether ovulution [sic] takes place at other times than in the viridescens) those of the nominal species D. miniatus, which spring. .” we think with Dr. Hallowell (’56) is a state of D. virides- cens. The color or character of the skin seems to be de- Jordan (1893), studying a population in Massachusetts, noted pendent upon the amount of moisture in the situations in which that that observations of fall mating by Gage were based upon they are found. Those from high and dry spots are redder and captive specimens, where their sexual activity may be due merely rougher than those from marshy situations.” to the “forced association of the two sexes . at a somewhat higher temperature than . their natural habitat. .” How- Definitive evidence that the forms were the same species did ever, Jordan also observed “on several occasions in the autumn not come for nearly 20 more years when Kelly (1878) reported months . pairs in the ponds engaged in the preliminary that he “. brought home a number of Diemyctylus miniatus ‘Liebesspeil,’ but have at no time observed any approach to Raf., or little red lizard or red eft, and after keeping them in a such an outbreak of sexual susceptibility as occurs in early dark box filled with saturated moss, they changed their color spring.

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