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Rhyacotriton (Dunn, 1920) Torrent Salamanders
Rhyacotriton cascadae (Good & Wake,
1992) Cascade Torrent Salamander
Rhyacotriton kezeri (Good & Wake, 1992)
Columbia Torrent Salamander
Rhyacotriton olympicus (Gaige, 1917) Olympic
Torrent Salamander
Rhyacotriton variegatus (Stebbins &
Lowe, 1951) Southern Torrent Salamander
Rhyacotritonidae is comprised of four species,
differentiated mainly by molecular data. All four species are found in the
western United States, and are characterized by their preference for cold
streams and temperate, coniferous forests. Originally, the single species in
the genus Rhyacotriton was included in the families Ambystomatidae and Dicamptodontidae, and
later placed at the family level, and further divided into four species...
Introduction & General Description
 Rhyacotritonids are collectively
referred to as Torrent Salamanders, and are found exclusively in the western
United States, specifically northern California, Oregon, and Washington. Torrent
Salamanders are found in humid coniferous forests, and well-oxygenated, cold
streams during breeding times. All species are biphasic, with aquatic larvae
and terrestrial adults. Rhyacotritonids are unique among most other
western species in that they may breed during any time of the year, although
breeding is
concentrated during spring and early summer.
 The four species are very similar in appearance, with a characteristic
tannish-gold to brown dorsal coloration and bright orange belly. The dorsum
is usually blotched with colors of light and dark brown, with scattered
white dots or blotches. Some individuals, or entire populations, may lack
dorsal blotching, and instead are a solid brown. The dorsal coloration may
be highly contrasted against the bright ventral surface at the sides of the
abdomen in darker individuals. There is much pattern and color variation
among populations and individual. The limbs and tail are short and robust in
all species. Rhyacotritonids are noted for their square-shaped
cloaca, see photo at left, resultant from swollen glands on either side of the vent (Petranka,
1998). Rhyacotritonids generally do not exceed 4.3 inches in total length,
with females averaging 2-3% larger than males (Petranka, 1998).
Rhyacotritonidae
is comprised of four species, in the single genus Rhyacotriton. This
genus was formerly comprised of one species, Rhyacotriton olympicus,
and included as a subfamily in Ambystomatidae, or in the family
Dicamptotontidae. Good & Wake, 1992, found that Dicamptodon,
Rhyacotriton, and Ambystoma were morphologically and biologically
distinct, and that Rhyacotriton warranted classification at the
family level. Rhyacotriton olympicus was eventually elevated to family
level. Further molecular analysis showed that R. olympicus consisted
of four distinct groups, based on protein variations (Good & Wake,
1992). These four groups became the four species currently recognized, R.
olympicus, R. cascadae, R. kezeri, and R. variegatus (Good &
Wake, 1992). Furthermore, each species contains well-differentiated
populations that often possess distinguishable coloration and
pattern.
There is no evidence of reproductive isolation among the species,
however, protein analysis show that gene exchange has not occurred between
the species for 3.2-9.5mya (Petranka, 1998). This lack of gene flow further
supports species level classification.
Larvae are stream-type, with short gills, long and slender bodies, and
low tail fins. The prominent eyes are positioned dorsally, and limbs are
functional upon hatching (Petranka, 1998). The fore mentioned
characteristics, in addition to reduced lungs, are thought to be derived
adaptations to a stream environment (Nussbaum & Tait, 1977; Worthington
& Wake, 1971). Metamorphosis is slow in Rhyacotritonidae, taking 3-5 years
(Petranka, 1998).
Rhyacotriton
cascadae (Good & Wake, 1992) Cascade Torrent Salamander
Taxonomic Synonyms: Rhyacotriton
cascadae (Good & Wake, 1992)
Vernacular Names: Cascade Torrent Salamander, Cascades Torrent
Salamander, Cascades Salamander
Blotching is generally heavy on the dorsal side of the R.
cascadae, and concentrated where the dorsal color contrasts the ventral
color, along the sides of the abdomen. Some individuals may be entirely
unspotted (Stebbins, 2003). Blotching or spotting is often present on the
orangish-yellow underside. Some populations have a dark band across the
posterior portion of the cloaca (Petranka, 1998).
R. cascadae
are found from the west slope of the Cascade Mountains, just north of Mt.
St. Helens, Skamania County, Washington, south to northeast Lane Co., Oregon
(Stebbins, 2003). R. cascadae are do not come into contact with the
other three species. Breeding occurs at nearly all times of
the year, but is concentrated in the warmer months of spring and early
summer. Females may mate two or more times per year. Although courtship is
unknown, eggs are thought to be deposited singly, and strewn about in deep
cracks and crevices in shaded streams (Petranka, 1998). Larvae
are stream type, with short gills, streamlined bodies, and low tail fins.
The tail fins are unmottled, and the eyes positioned dorsally. Larvae are
light brown dorsally, with cream colored bellies. Light black and white
spots are often found on the dorsal and ventral surfaces. Older larvae may
grow up to .37 mm per month (Nussbaum & Tait, 1977), and transform
around 37-45 mm in total length. Metamorphosis is slow, taking 3-5 years.
Juveniles reach sexual maturity at 1-1.5 years after metamorphosis, at
5.5-6.0 years old (Petranka, 1998).
Rhyacotriton
kezeri (Good & Wake, 1992) Columbia Torrent Salamander
Taxonomic Synonyms: Rhyacotriton
cascadae (Good & Wake, 1992)
Vernacular Names: Cascade Torrent Salamander, Cascades Torrent
Salamander, Cascades Salamander
Blotching is generally heavy on the dorsal side of the R.
cascadae, and concentrated where the dorsal color contrasts the ventral
color, along the sides of the abdomen. Some individuals may be entirely
unspotted (Stebbins, 2003). Blotching or spotting is often present on the
orangish-yellow underside. Some populations have a dark band across the
posterior portion of the cloaca (Petranka, 1998).
R. cascadae
are found from the west slope of the Cascade Mountains, just north of Mt.
St. Helens, Skamania County, Washington, south to northeast Lane Co., Oregon
(Stebbins, 2003). R. cascadae are do not come into contact with the
other three species. Breeding occurs at nearly all times of
the year, but is concentrated in the warmer months of spring and early
summer. Females may mate two or more times per year. Although courtship is
unknown, eggs are thought to be deposited singly, and strewn about in deep
cracks and crevices in shaded streams (Petranka, 1998). Larvae
are stream type, with short gills, streamlined bodies, and low tail fins.
The tail fins are unmottled, and the eyes positioned dorsally. Larvae are
light brown dorsally, with cream colored bellies. Light black and white
spots are often found on the dorsal and ventral surfaces. Older larvae may
grow up to .37 mm per month (Nussbaum & Tait, 1977), and transform
around 37-45 mm in total length. Metamorphosis is slow, taking 3-5 years.
Juveniles reach sexual maturity at 1-1.5 years after metamorphosis, at
5.5-6.0 years old (Petranka, 1998).
Rhyacotriton
kezeri (Good & Wake, 1992) Columbia Torrent Salamander
Taxonomic Synonyms: Rhyacotriton
kezeri (Good & Wake, 1992)
Vernacular Names: Columbia Torrent Salamander, Oregon Olympic
Salamander
R. kezeri usually lack blotching on the brown or
greenish dorsum, except those populations near the contact zone with R.
variegatus in Tillamook Co., Oregon (Good & Wake, 1992). In some
populations and individuals there is a smooth transition from the dark
dorsal coloration to the paler ventral coloration, occurring along the sides
of the abdomen. However, some may have highly contrasting dorsal and ventral
coloration that end abruptly along the abdomen. The ventral pattern is also
variable, consisting of orange or yellow coloration with or without mild
spotting. Hatchling larvae possess two dark,
longitudinal rows along the back (Petranka, 1998). R.
kezeri are found near Chehalis River in Gray Harbor Co., Washington,
south to the start of R. variegatus populations near the Little
Nestucca River and Grande Ronde Valley in Polk, Tillamook, and Yamhill
Counties, Oregon (Stebbins, 2003). R. kezeri do not hybridize with R.
variegatus at the contact zone (Petranka, 1998).
Rhyacotriton
olympicus (Gaige, 1917) Olympic Torrent Salamander
Taxonomic Synonyms: Ranodon
olympicus (Gaige, 1917), Rhyacotriton olympicus (Dunn, 1920)
Rhyacotriton olympicus olympicus (Stebbins & Lowe, 1951)
Vernacular Names: Olympic Torrent Salamander, Mountain Salamander,
Olympic Salamander, Olympic Mountain Salamander, Northern Olympic
Salamander
R. olympicus is the largest species of the genus. The
dorsum is usually dark brown or greenish, with little or no dark spotting.
The ventral surface is orange or yellow, with little or no dark spotting.
The transition from dorsal to ventral coloration is abrupt, forming a
"wavy" line along the sides of the abdomen (Stebbins, 2003), which
can be used to differentiate R. olympicus from the other
species. R. olympicus are found from the Olympic
Peninsula in Clallam, Grays Harbor, Jefferson and Mason Counties,
Washington, south to the Chehalis River Valley (Stebbins, 2003). R.
olympicus do not come into contact with the other three species.
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R. cascadae. Photo © Gary Nafis,
California
Reptiles and Amphibians
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R. cascadae. Photo © Gary Nafis,California
Reptiles and Amphibians |
R. cascadae. Photo © Gary Nafis,
California
Reptiles and Amphibians
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R. olympicus.
Adult from Olympic National Park, Quinault Rain Forest, Jefferson Co.,
Washington. Photo © 2002 William Flaxington
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R. olympicus.
Adult from Olympic National Park, Quinault Rain Forest, Jefferson Co.,
Washington. Photo © 2002 William Flaxington |
R. cascadae. Wavy transition from dorsal
to ventral surface. Photo © Gary Nafis,
California
Reptiles and Amphibians
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Rhyacotriton
variegatus (Stebbins & Lowe, 1951) Southern Torrent Salamander
Taxonomic Synonyms: Rhyacotriton
olympicus variegatus (Stebbins & Lowe, 1951), Rhyacotriton
variegatus (Good & Wake, 1992)
Vernacular Names: Southern Torrent Salamander, California Mountain
Salamander, Southern Olympic Salamander
R. variegatus is perhaps the most blotched and
spotted species. The dorsum typically consists of a brownish base color
blotched with black or dark brown, and sometimes dotted with white. The
ventral surface is also usually spotted with black or dark brown. Northern
populations may have reduced or finer blotching on the dorsal and ventral
surfaces, and brighter colored bellies (Stebbins, 2003). Heavily blotched
individuals may also have a preorbital stripe anterior to each eye (Petranka,
1998).
Breeding occurs at nearly all times of the year, with
minimal activity during the winter months, and from May to August (Petranka,
1998). It is thought that southern populations oviposit earlier each year
than northern populations (Petranka, 1998). Females may mate two or more
times per year. Although courtship is unknown, eggs are thought to be
deposited singly, and strewn about in deep cracks and crevices in shaded
streams (Petranka, 1998). Like R. kezeri, hatching likely occurs 5-6
months after deposition. Clutch size is proportional to the
size of the female, with larger females producing larger clutches. Clutch
size is rather small for stream breeding species, averaging between 4 and 16
(Petranka, 1998). Larvae are stream type, with short
gills, streamlined bodies, and low tail fins. The tail fins are unmottled,
and the eyes positioned dorsally. Larvae are light brown dorsally, with
cream colored bellies. Light black and white spots are often found on the
dorsal and ventral surfaces. Larvae may grow up to .42-.50 mm per month
during the first two years of life (Nussbaum & Tait, 1977), and
transform around 30-90 mm in total length, depending on the geographic
population. Welsh & Lind, 1992, report northern California larvae
averaging growth of 2.3 mm per year. Metamorphosis is slow, taking between
1-3 years. Juveniles reach sexual maturity at 1-1.5 years after
metamorphosis, at 4.0-5.0 years old (Petranka, 1998). R.
variegatus are found from the contact zone with R. kezeri near
the Little Nestucca River and Grande Ronde Valley in Polk, Tillamook, and
Yamhill Counties, Oregon, south to Point Arena, Mendocino Co., California (Stebbins,
2003). R. variegatus isolates are also found on the west slope of the
Cascade Mountains, Douglas Co., Oregon, and in the upper drainage of McCloud
River, Siskiyou Co., California (Stebbins, 2003; Petranka, 1998). R.
variegatus does not hybridize with R. kezeri at the contact zone
(Petranka, 1998).
Ecology
Rhyacotritonids are found in coastal areas of northern California, Oregon, and
Washington. There is a contact zone between R. variegatus and R.
kezeri in Tillamook Co., Oregon, although hybridization does not occur
between any of the species. The remaining species are geographically isolated
from one another. Each species consists of rather well-differentiated
populations that inhabit a rather specialized environment. The
terrestrial habitat consists of humid, coniferous forests near aquatic sources.
Old-growth forests with abundant mosses and >80% canopy enclosure are ideal
(Welsh & Lind, 1996). Adults and juveniles are rarely found more than a few
meters from streams, springs, or seepages. Microhabitats of adults include
fissures in streambeds, cracks and crevices in cliff faces, and beneath
partially exposed stream rocks. Rhyacotritonids can tolerate very little water
loss in comparison to other caudate species (Petranka, 1998). Adults
and larvae are found in cold, permanent streams, springs, and seepages with
gravel or cobble substrates. The preferred aquatic habitat is heavily shaded,
cold, flowing waters having northerly visage (Petranka, 1998). Adults may enter
the water at all times of the year, but breeding is concentrated in the warmer
months (Petranka, 1998). Larvae usually are hidden in the loose gravel, or under
stones of streams, springs, and seepages (Petranka, 1998). Both larvae and
adults are typically found in no more than an inch or so of water, but will
retreat to deeper waters if disturbed. There is a contact
zone between R. kezeri and R. variegatus along the Little Nestucca
River, Oregon, where hybridization does not occur. R. cascadae and R.
olympicus are isolated from the other species. As mentioned previously, the
four species do no hybridize.
References
Center for North American Herpetology. (2003).
http://www.cnah.org/
(Accessed: 2000).
Good, D. A., and D. B. Wake. 1992. Geographic variation and speciation in the
torrent salamanders of the genus Rhyacotriton (Caudata: Rhyacotritonidae).
University of California Publications in Zoology 126: 1-91.
Nafis, Gary. Rhyacotriton variegatus (database entry). California
Reptiles & Amphibians.
http://www.californiaherps.com/salamanders/pages/r.variegatus.html
(Accessed: 2004).
Nature Serve Explorer (Database). Nature Serve.
http://www.natureserve.org/explorer/index.htm
(Accessed: 2000-2003).
Nussbaum, R. A., and C. K. Tait. 1977. Aspects of the life history and
ecology of the Olympic Salamander, Rhyacotriton olympicus (Gaige). The
American Midland Naturalist 98:176-199.
Petranka, James W. Salamanders of the United States and Canada. Smithsonian Institution Press, 1998.
Stebbins, Robert C. Western Reptiles and Amphibians (third edition). Houghton Mifflin Company, 2003.
Welsh, H. H., Jr., and A. J. Lind. 1992. Population ecology of two relictual
salamander populations from the Klamath Mountain of northwestern California. In
Wildlife 2001: Populations, Elsevier Applied Science, London: 419-437.
Welsh, H. H., Jr., and A. J. Lind. 1996. Habitat correlates of the southern
torrent salamander, Rhyacotriotn variegatus (Caudata: Rhyacotritonidae),
in northwestern California. Journal of Herpetology 30: 385-398.
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