Browsing by Author "Conant, Roger, 1909-"
Now showing 1 - 8 of 8
Results Per Page
Sort Options
Item Evidence for the specific status of the water snake Natrix fasciata. American Museum novitates ; no. 2122(New York, N.Y. : American Museum of Natural History, 1963) Conant, Roger, 1909-"A new interpretation of the sipedon-fasciata complex of the water snake genus Natrix is proposed. Natrix fasciata is elevated to specific status with the inclusion of three fresh-water races, fasciata, confluens, pictiventris; pending studies on the salt-marsh snakes, the forms clarki, compressicauda, and taeniata are retained as additional races of fasciata. The remaining members of the complex, namely, sipedon, pleuralis, and insularum, are left in the species Natrix sipedon. Sympatry between the species sipedon and the species fasciata is demonstrated over a wide area, with specific instances listed from Arkansas, Florida, Georgia, Illinois, Louisiana, Mississippi, North Carolina, Oklahoma, and Tennessee. The two species are allopatric in many other areas; for example, from east central North Carolina to Georgia their respective ranges meet on opposite sides of the Fall Line. Intermediate specimens that combine characters of both sipedon and fasciata are described from several localities near the Fall Line in South Carolina and Georgia where there is evidence of recent disturbance of the habitat by mankind. Such intermediate specimens are believed to be the products of hybridization. Many specimens of sipedon from near the common boundary of the two species in the Carolinas and extreme southeastern Virginia exhibit head patterns that include a dark postocular element grossly similar to the dark postocular stripe that is characteristic of fasciata. This phenomenon is interpreted as convergence. Natrix sipedon occurs on the Outer Banks of North Carolina and in brackish waters along the inner (mainland) edge of Pamlico Sound. Natrix fasciata in the same general region is confined to fresh-water habitats on the mainland, except that it apparently has fortuitously reached the Shackleford Banks, which lie close inshore. On this island, on the adjacent mainland, and at the head of the Pungo River estuary, in all of which fresh- and brackish-water habitats are in close proximity, there is evidence of hybridization between sipedon and fasciata"--P. 33-34.Item Miscellaneous notes and comments on toads, lizards, and snakes from Mexico. American Museum novitates ; no. 2205(New York, N.Y. : American Museum of Natural History, 1965) Conant, Roger, 1909-Item A new water snake from Mexico, with notes on anal plates and apical pits in Natrix and Thamnophis. American Museum novitates ; no. 2060(New York, N.Y. : American Museum of Natural History, 1961) Conant, Roger, 1909-"A new striped race of the Mexican west coast water snake, which bears a remarkable resemblance to a garter snake (Thamnophis), is diagnosed and described as Natrix valida thamnophisoides. Populations of this form are the only members of the species complex known to occur at fairly high elevations. Their distribution is compared with the ranges of the lowland populations, and intergradation between thamnophisoides and subspecies valida is discussed. It is shown that paired apical pits occur on the dorsal scales, especially of the nuchal region, in many Thamnophis, thus refuting the statement of several authorities that such pits are absent in all garter snakes. It is also shown that pits may be absent in some water snakes, especially in the Natrix valida complex. The condition of the anal plate, whether single or divided, although widely used in keys for the separation of the genera Natrix and Thamnophis, also varies, at least in a few species"--P. 20-21.Item Notes on three Texas reptiles, including an addition to the fauna of the state. American Museum novitates ; no. 1726(New York, N.Y. : American Museum of Natural History, 1955) Conant, Roger, 1909-Item A review of the water snakes of the genus Natrix in Mexico. Bulletin of the AMNH ; v. 142, article 1(New York : [American Museum of Natural History], 1969) Conant, Roger, 1909-"This study is concerned primarily with geographical distribution and variation among the three species of water snakes of the genus Natrix in Mexico, but considerable information on ecology and natural history is also included. Among the three species, Natrix valida occurs in western Mexico, but Natrix erythrogaster and Natrix rhombifera not only inhabit eastern Mexico but also range widely in the United States. In the arid northern portions of Mexico these snakes are confined to the rivers and occasional springs and swamps, and the populations occupying individual drainage systems were formerly completely isolated from those of other systems. Theoretically it is now possible in a few areas, however, for semiaquatic snakes, such as Natrix, to move from one river system to another by following the canals of recently developed irrigation projects. Isolation has been of sufficiently long duration to permit the evolution of two distinct subspecies of Natrix erythrogaster, one each in the Río Nazas and Río Aguanaval. A third race of erythrogaster occurs in northeastern Mexico. Natrix rhombifera, which also has three subspecies in Mexico, ranges widely through the lowlands of eastern Mexico. One race occurs in the northeastern states, a second has its center of abundance in the vast and complex drainage system that discharges into the Gulf of Mexico through the Río Pánuco at Tampico, and the third is widespread through the swamplands of southern Veracruz and Tabasco. The distribution of the collecting localities, when plotted on a map of the drainage systems, indicates that stream piracy probably has occurred in Nuevo León and that the Río San Juan has decapitated the headwaters of the Río San Lorenzo of the Río Conchos-San Fernando system, with consequent transfer of the aquatic and semiaquatic faunas to the drainage of the Rio Grande. The break between the two southern races of rhombifera occurs in the region where the Sierra Chiconquiaco and associated highlands extend eastward to the Gulf of Mexico, south of Nautla, Veracruz, and effectively separate the Gulf coastal plain into northern and southern sectors. On the west coast there is a similar, but less massive disruption of the coastal plain immediately south of San Blas, Nayarit. Three races of Natrix come together in this area. One occurs northward as far as the Río Yaqui in Sonora; a second ranges southward along the tenuous and frequently interrupted coastal plain at least to the vicinity of Acapulco, Guerrero; and the third occupies an outlier of the Mexican altiplano in the vicinity of Tepic, Nayarit. A fourth race of valida is confined to the Cape Region of Baja California. The present distribution of the genus Natrix in Mexico suggests that these reptiles were much more widely distributed during one or more pluvial periods of late Pleistocene or Recent time and that increasing aridity in western North America has resulted in the fragmentation of their ranges and the establishment of numerous isolated populations, especially in rivers in the northern part of Mexico. Earlier pluvial periods may also have permitted Natrix valida to range northward around the head of the Gulf of California and from there southward through Baja California, which would explain the presence of the isolated subspecies that has survived in the Cape Region. The various taxa are discussed in detail in the present paper, with emphasis on variation in scutellation and color patterns. Distributions are plotted on a series of six maps. Ten plates, two in color, illustrate all the various subspecies from life; 12 additional plates illustrate habitats in which these reptiles have been collected. Field work in Mexico was conducted in each of 10 different years, and the total accumulated time, including work on parallel studies on garter snakes of the genus Thamnophis, amounted to almost exactly a full year. During these investigations every state and territory in Mexico was visited at least once, as well as the Federal District"--P. 132.Item A review of two rare pine snakes from the Gulf coastal plain. American Museum novitates ; no. 1781(New York, N.Y. : American Museum of Natural History, 1956) Conant, Roger, 1909-Item Turtles of the family Kinosternidae in the southwestern United States and adjacent Mexico : identification and distribution. American Museum novitates ; no. 2642(New York, N.Y. : American Museum of Natural History, 1978) Conant, Roger, 1909-; Berry, James F."Two keys for the identification of the kinosternids of the United States-Mexican border region, one for adults and one for juveniles, are presented in an effort to alleviate the confusion that has long existed in attempting to distinguish among the members of the group. Taxa involved are Kinosternon flavescens flavescens, K. hirtipes murrayi, K. sonoriense, K. subrubrum hippocrepis, Sternotherus carinatus, and S. odoratus. Numerous errors from the literature that were based on the misidentification of specimens are corrected"--P. [1].Item Zoological exploration in Mexico : the route of Lieut. D.N. Couch in 1853. American Museum novitates ; no. 2350(New York, N.Y. : American Museum of Natural History, 1968) Conant, Roger, 1909-; Couch, Darius Nash.