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Calotriton asper (Gray, 1858) Pyrenean Brook Salamander, Pyrenean
Mountain Newt
formerly: Euproctus asper (Duges, 1852)
Physical Description
 Calotriton
apser is the largest of the Brook Salamanders, measuring 4-6
inches (10-16cm) as adults. The rough skin of the dorsum is light or
dark gray, to brown with yellowish spots. The ventral side consists of a
wide, jagged yellow or orange stripe, often with small black blotches.
Some individuals may possess a solid or discontinuous yellow or orange
stripe down the dorsum and top of tail. Alpine populations are typically
darker in coloration. The darker color indicates the presence of higher
concentrations of melanophores, which protect the salamander from
powerful UV radiation, as well as aid in the absorption of heat. The
tail is laterally compressed (when aquatic), and typically the same
length of the body from snout to vent. Females can be distinguished from
males by their elongated, pointed cloacal opening (males are rounded)
(van der Meijden, 2002). Males can live up to 20 years, and females
up to 26 years.
Subspecies
Calotriton asper asper (Duges, 1852), and Calotriton asper
castelmouliensis (Wolterstorff, 1925). Although formally recognized
as two subspecies, many do not distinguish between the two, and both are
sometimes considered a single form (Hofrichter, 2000).
Distribution & Natural Habitat
 Calotriton asper are found throughout the French and Spanish Pyrenees
Mountains, with concentrations in the eastern and central sections.
C. asper
are distributed across a wide altitudinal range,
including elevations of 575 - 9500 feet (175 - 2900 meters), with
population concentrations around the 6560 feet (2000 meter) area (Hofrichter,
2000). Populations tend to reside in areas that remain frost-free for 4
to 5 months out of the year. During snowy winters, C. asper will
hibernate buried under ground. During their active period (spring and
summer), adult C. asper can be found in cold, running
streams and brooks (usually around 41°F to 59°F, or 5°C to 15°C).
Cave dwelling populations are adapted to feeding only on the scarce
invertebrate species present in their dark homes, and can survive for several
months with very little food, or no food at all. Although not unique to
cave-dwelling individuals, the approach to hunting in complete darkness changes
from that of daytime or low lighting.
Breeding Behavior
Breeding takes place in spring and summer,
usually between April and August, in aboveground areas. The exact time
and duration varies for different populations, and may begin as early as
winter in some cave-dwelling populations (Hofrichter, 2000). Males
become territorial and aggressive during the breeding season, and will
mark their territories with chemical secretions. Territorial males will
ward off competing males by means of beating the ground with the tail,
and sometimes biting (Hofrichter, 2000).
C. asper are unique in that their eggs are fertilized
by direct cloacal contact. To signal the female, the male
will raise his tail in an almost-vertical position (van der Meijden,
2002). Amplexus consists of the male gripping the female by wrapping his
tail around her cloacal region in such a way that his cloaca is in
direct contact with hers. During amplexus, the male transfers
spermatophores directly to the female’s cloaca. Amplexus may last for
several hours, and can sometimes appear to be a jumbled knot of newts
(as in the photo above).
The female produces 20-60 eggs, and attaches them
individually under rocks or other debris in cool, moving streams or
brooks (van der Meijden, 2002). Eggs are approximately 3.5-5mm in
diameter, excluding the gelatinous outer protection (van der Meijden,
2002). Upon hatching, larvae are approximately 13mm, with reduced gills,
rounded tail, and streamlined bodies (typical stream-type larvae).
Metamorphosis generally begins 14 months after hatching (generally the
following summer), when the larvae are 50-60mm in length (van der
Meijden, 2002). Higher elevation populations may remain in the larval
stage for two years, beginning metamorphosis two summers after hatching,
and measuring 95mm(van der Meijden, 2002). Complete metamorphosis can
take a month or two at average summer temperatures of 50°F-55°F (10°C-13°C),
and neotenic specimens have been discovered in the Valle de Aran (van
der Meijden, 2002).
The young morphs are inconspicuously dark gray to black, with
or without a yellow-orange dorsal stripe and yellow spots. Sexual
maturity is reached at approximately 2-3.5 years for males, and up to 6
years for females (depending on the elevation).
Feeding Habits
C. asper are opportunistic feeders, as well as hunters. They
accept an array of food items, including aquatic and terrestrial
insects, insect larvae, aquatic crustaceans, snails, slugs, mussels, and
amphibian eggs and larvae (including their own) (Hofrichter, 2000).
Cave dwelling populations are adapted to feeding only on the
scarce invertebrate species present in their dark homes, and can survive
for several months with very little food, or no food at all (Hofrichter,
2000). Although not unique to cave-dwelling individuals, the approach to
hunting in complete darkness differs from that of daytime or low
lighting. When in complete darkness, C. asper will abandon the
"straight and rapid" lunging approach, and opt for a slow,
persistent chase across much longer distances (Hofrichter, 2000). To
capture food, cave dwelling Calotriton rely on smell and motion
detection through vibrations in a similar manner as other cave dwelling
species, such as the Olm, although the sense is less developed in
Calotriton.
Aboveground Calotriton populations rely mainly on motion detection
by sight, and typically will not pursue their prey over long distances (Hofrichter,
2000).
Despite the less-than-abundant food supply in most caves,
cave dwelling species have some advantages over their ground dwelling
counterparts; there are no predators in the caves, the temperatures are
relatively stable (no extremes), and the risk of dehydration is
virtually absent.
Threats
C. asper is a declining species in some regions due to the
introduction of brown trout into their immediate ecosystem, and
increased pollution from mass tourism) (van der Meijden, 2002). Other
factors aiding in the decline of some populations include loss of
habitat caused the damming of breeding brooks and streams, road
construction, fatalities from autos, and automobile pollution) (van der
Meijden, 2002). Populations still thrive where the more inaccessible
areas where pollution, construction, and foreign game fish have not been
introduced.
Misc. Notes
Through mitochondrial DNA sequences, the genus Calotriton
has been shown to be closely related to the genus Triturus. Calotriton
and Euproctus split from the common ancestor some 9 million
years ago, when the Pyrenees Mountains separated from the islands of
Corsica and Sardinia (Hofrichter, 2000).
References
Uiblein, F., J.P. Durand, C. Juberthie, & J. Parzefall. 1992. Predation in
caves: the effects of prey immobility and darkness on the foraging behaviour of
two salamanders, Calotriton asper and Proteus anguis.
Bahavioural Processes 28: 33-40.
Griffiths, Richard A. Newts and Salamanders of Europe.
San Diego, CA: Academic Press Inc., 1996.
Hofrichter, Robert. Amphibians: The World of Frogs, Toads, Salamanders and Newts.
Firefly Books, 2000.
Obst, Fritz Jugen, Udo Jacob, and K. Richter. Completely Illustrated Atlas of Reptiles and Amphibians for the Terrarium.
Neptune City, NY: T.F.H. Publications, Inc., 1989.
van der Maijden, Arie. (2002). Calotriton asper, Pyrenean Brook Newt. AmphibiaWeb.
http://elib.cs.berkeley.edu/cgi-bin/amphib_query?table=amphib&special=one...etc. (Accessed: 2002).
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