Michoacan Stream Salamander, Puerto Hondo Stream Salamander
© 2018 Axel Hernandez (1 of 8)
Larvae of Ambystoma ordinarium resemble those of Ambystoma opacum, and have sparse, but evenly distributed melanophores in addition to the rows of light silver-yellow specks. The larval fins are well-developed, and darken and mottle at maturity. Larval gills are reduced in size but bushy. Ambystoma ordinarium larvae reach a maximum size of 100 mm SVL and 191 mm in total length. Ambystoma ordinarium possesses features of both pond-dwelling and mountain brook-dwelling species. The dorsal and ventral fins of hatchlings are fully developed, as is typical of pond-type larvae, while gills are both diminutive and bushy, as is typical of mountain brook-type larvae. (Anderson and Worthington 1971; Anderson 1975).
Distribution and Habitat
Life History, Abundance, Activity, and Special Behaviors
Neoteny is prevalent in this polymorphic species, but not uniform within populations. Metamorphic adults are terrestrial and have been observed to occupy the high-elevation woods and streamside habitats alongside juveniles. Paedomorphic adults and larvae are found in the montane streams (Anderson and Worthington 1971).
An average of 109 eggs are laid singly or in clusters of 2-5 eggs onto the undersurfaces of roots, branches, and rocks, hanging free in the current. Eggs are pigmented and measure 9.9 mm including all layers of egg capsules. Each egg is encased in two inner capsules plus a third, thicker outer capsule. Egg clusters are observed not within an envelope, but consisting of individual eggs stuck together (Anderson and Worthington 1971).
Ambystoma ordinarium appears to have a prolonged breeding season which may extend throughout the entire year, unusual for a temperate salamander. In the wild, eggs, embryos of various stages and larvae of different sizes have been found in both July and January. The testis and cloacal glands of males undergo no periodic changes once mature, suggesting the capability to reproduce year-round. Periodic changes do occur in females, but reproductive cycles are asynchronous within a population, evidence also of the species’ ability to breed throughout the year. Opportunistic breeders are able to continuously add small numbers of larvae to colonies throughout the year. Since environmental conditions are fairly consistent year-round, the staggered breeding may serve to reduce intraspecific competition for resources in the small mountain streams (Anderson and Worthington 1971).
Stream-breeding is unusual among ambystomatid salamanders, as most of these species breed in ponds. Only two Ambystoma species, Ambystoma rosaceum and Ambystoma ordinarium, breed in moving water in a natural setting. It is thought that Ambystoma ordinarium has invaded stream habitats relatively recently, in evolutionary time. As would be expected for stream-dwelling salamanders, older larvae and neotenic adults show reduced fins, possess no balancers, develop limbs and digits early, and have a reduced gill size. However, new hatchlings have fully developed fins and well-developed ypsiloid cartilage, as is typical of pond-breeding salamanders. The hatchlings of Ambystoma ordinarium are thus more mature than those of typical pond breeders, but less mature than those of stream breeders. Adults and larvae alike walk on the bottom more than they swim (Anderson and Worthington 1971).
Ambystoma ordinarium is perhaps the only primarily diurnal species of Ambystoma. Individuals generally remain hidden under cover of stream banks or underneath logs in the early part of the day, coming out by late morning (Anderson and Worthington 1971). It is possible that this behavior can be attributed to the slight rise in cold mountain water temperatures that facilitates daytime feeding. The lack of natural predators also encourages diurnal activity (Alavarado-Diaz et al. 2002).Ambystoma ordinarium feeds on both terrestrial and aquatic prey. Terrestrial prey items for this species include grasshoppers, as well as ants, leafhoppers, scuds, earthworms, and nematodes. Aquatic prey items include aquatic insect larvae (especially caddisfly larvae), small aquatic beetles, and clams (Alavarado-Diaz et al. 2002; Duellman 1961).
Trends and Threats
Possible reasons for amphibian decline
Local pesticides, fertilizers, and pollutants
Alavarado-Diaz, J., Garcia-Garrido, P., and Suazo-Ortuño, I. (2002). ''Food habits of a paedomorphic population of the Mexican salamander, Ambystoma ordinarium (Caudata: Ambystomatidae).'' The Southwestern Naturalist, 28(1), 100-102.
Anderson, J. D. (1975). ''Ambystoma ordinarium.'' Catalogue of American Amphibians and Reptiles. Society for the Study of Amphibians and Reptiles, 164.1-164.2.
Anderson, J. D., and Worthington, R. D. (1971). ''The life history of the Mexican salamander Ambystoma ordinarium Taylor.'' Herpetologica, 27, 165-176.
Duellman, W. E. (1961). ''The amphibians and reptiles of Michoacán, México.'' University of Kansas Publications, Museum of Natural History, 15, 1-148.
IUCN, Conservation International, and NatureServe. 2006. Global Amphibian Assessment: Agalychnis annae. www.globalamphibians.org. Accessed on 19 October 2007.
Shaffer, H. B. (1984). ''Evolution in a paedomorphic lineage. II. Size and shape in the Mexican ambystomatid salamanders.'' Evolution, 38, 1194-1206.
Weisrock, D. W., Shaffer, H. B., Storz, B. L., Storz, S. R., and Voss, S. R. (2006). ''Multiple nuclear gene sequences identify phylogenetic species boundaries in the rapidly radiating clade of Mexican ambystomatid salamanders.'' Molecular Ecology, 15(9), 2489-2503.
Written by Sharon Liu (sharonliu AT berkeley.edu), UC Berkeley
First submitted 2007-10-18
Edited by Kellie Whittaker (2007-10-20)
Species Account Citation: AmphibiaWeb 2007 Ambystoma ordinarium: Michoacan Stream Salamander <http://amphibiaweb.org/species/3844> University of California, Berkeley, CA, USA. Accessed Nov 14, 2018.
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Citation: AmphibiaWeb. 2018. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 14 Nov 2018.
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