Arroyo toad
| Arroyo toad | ||||||||||||
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Arroyo toad ( Anaxyrus californicus ) |
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| Anaxyrus californicus | ||||||||||||
| ( Camp , 1915) |
The arroyo toad ( Anaxyrus californicus ) is a medium-sized California toad. The common name refers to their main habitat : Arroyo is a highly lined, very shallow river called, which often dries up in summer and after heavy rains leads to water again and is even flooded.
This toad was first discovered by the American biologist and zoologist Joseph Grinnell on April 1, 1904 in Tujunga Wash , near Sunland , Los Angeles County . However , it was not described until 1915 by the paleontologist and zoologist Charles Lewis Camp after a specimen found in 1912 on a lawn in Santa Paula , Ventura County .
features
morphology
Male arroyo toads grow to 44 to 58 mm long, female 44 to 68 mm long.
In terms of physique, the toad is very short and thick and equally covered with brown-tipped warts everywhere. The head is very short and wide, the crests of the skull are weak or absent and the nasal region lies on a bony protrusion. The distance between the eyes, which narrows slightly towards the front, is about 4.6 to 5.75 mm, and the mouth is about 6.5 to 8 mm wide. Larger, mostly light-colored warts can be found behind the corners of the mouth. The eyelids are provided with tubercles . The tympanum is oval and its mean diameter is shorter than the diameter of the eye. There are at least twelve large whitish tubercles under the tympanum, and several of them are also present behind the tympanum.
The thighs are very short. Compared to the front legs, the rear legs are relatively long. There are no glands on the thighs. About half of the feet are webbed. On its hind feet, the arroyo toad has a very small, round, wart-like outer metatarsal tubercle that is also used for digging. The inner metatarsal tubercle has a sharp-edged callus.
The skin secreting secretions is relatively soft and the warts on the back are generally somewhat smaller and bordered with black. Only occasionally are the warts somewhat larger and then have a rather sharp point, sometimes several. The parotid glands are relatively far apart, are almost twice as long as they are wide, elongated oval shaped and become darker and wider towards the rear. The front third of the parotid glands has the same light color as the band between the eyes, and there are two small black spots at the back, which meet at an obtuse angle towards the front.
coloring
The basic color of the arroyo toads is usually gray or olive-brown to dark olive-colored dorsally , but brown individuals have also been observed. In pre-adult animals, light and dark areas on the head and back are still in stark contrast to one another, which fades with increasing age. A lighter area can be seen on the back.
Coloring of females
In contrast to the basic color, they are colored ocher-olive on the dorsal side and white on the ventral side. After moulting, they are noticeably lighter. On the mouth, two parallel black vertical stripes meet a horizontal stripe in front of the eyes. From the middle of the upper eyelid there is a black stripe diagonally to the back, which becomes wider towards the back line, but these stripes do not meet. Behind this horizontal stripe, they generally have a wood-brown to hazelnut-colored band between the eyes, which in pre-adult animals is ocher-olive-colored, and which continues under the eyes to the mouth. There is another spot of the same color right between the nostril and the eye, and there is a black spot under the eye. In front of the parotid glands there is a matt black spot with a light brown or hazelnut-colored wart in the center. The front third of the parotid glands has the same light color as the band between the eyes, and there are two small black spots at the back, which meet at an obtuse angle towards the front. Immediately behind each of the parotid glands is another large black spot, behind which a row of ocher-olive-colored warts extends laterally at an angle to the groin area. A black line runs under this row of warts and sometimes a hazel-colored band over it. After moulting, these wart marks stand out quite noticeably. The throat is pale ocher-olive or linden-colored, the inflated, almost spherical throat pouch is white to pink, the underside of the foot is ocher-wine-red and the inside of the hind legs and the lower abdomen are light wine-colored to fawn or light grayish-wine-colored. Behind the corners of the mouth there are two or three ocher-olive-colored warts. The thighs are provided with horizontal stripes, one half on the front thigh and two black stripes on the front and rear lower legs. The pupil has a light bluish-gray-yellow border above and below with spots of the same color or ocher-apricot-colored spots on the otherwise black iris .
Coloring of the males
In contrast to the basic coloration, the males are dorsally dull dark gold yellow, grayish to dark grayish olive colored. A light olive-ocher-colored or golden-yellow band runs between the eyes. The iris is more blotchy and of a not as strong black as in the female. The middle and lower part of the throat and the parotid glands are colored ocher to wine red. The dorsal spots do not stand out quite as noticeably as in the females. The warts, which are particularly noticeable because of their shape and size, have one or more, mostly brownish tips. The wart lines, which run obliquely laterally from the parotid glands to the groin , stand out clearly from the rest of the body color.
Differences from other species
Prairie toad
It can easily be confused with the fully grown prairie toad ( Anaxyrus cognatus ), which is about a third larger , but the arroyo toad has only a very small outer metatarsal tubercle under the somewhat longer hind foot, its less pronounced crests are about 10 to 20% wider and the color scheme on the back is more uniform, with no major green spots. In addition, the parotid glands are somewhat larger. The abdominal surface is noticeably finer granulated.
Anaxyrus microscaphus
Compared to Anaxyrus microscaphus , the parotoid glands in Arroyo toads are oval and longer. They are almost parallel to each other. While the skin of A. microscaphus is relatively smooth, it is rougher in the arroyo toad. A. microscaphus is also only native to Utah , Nevada and Arizona , the range does not overlap with that of the arroyo toad. Confusion is therefore impossible in nature.
Type specimen
The type specimen is labeled with the number 4364 at the Museum of Vertebrate Zoology at the University of California, Berkeley . It is female and was found on May 22, 1912 at around 8 p.m. on a lawn in the middle of Santa Paula, Ventura County, 150 feet above sea level. The site is in the semi-arid fauna of San Diego , where the rivers periodically dry up in summer. Charles Lewis Camp described it in 1915 in the University of California publications in zoology under the scientific name Bufo cognatus californicus . It was then considered a subspecies of the prairie toad ( Bufo cognatus ). In the meantime it was placed as a subspecies to other Bufo species, most recently to the very similar toad Bufo microscaphus . After recognition as a separate species in 1998, it was classified together with all other North American representatives of the genus Bufo in the genus Anaxyrus .
Anatomical size specifications of the type specimen:
- Body length: 63.6 mm
- Head dimensions (length × width): 17.7 × 25 mm
- Orbit (diameter): 8.5 mm
- Interorbital space : 4.6 mm
- Foreleg:
- Lower leg length: 16.6 mm
- Foot length: 16 mm
- Hind leg:
- Thigh length: 25.7 mm
- Lower leg length: 24.6 mm
- Foot length without toes: 15 mm
- Total foot length: 43 mm
Cycle of life
Life expectancy
By marking individual individuals, it was found that arroyo toads have an approximate life expectancy of five years. It is predominantly the females that survive that long. If North American bullfrogs appear in the breeding area, the breeding season is severely disturbed, as arroyo toads are hunted and eaten especially then. On average, only one male for every 19 females was counted during this period, which often led to local extinction. In addition, 55 to 80% die during the winter (torpor).
Courtship
It has been observed that male pre-adult animals around ten to twelve months old have already performed courtship songs. Still, none of them have mated as the females prefer the largest males. Mating was not observed until the following spring (second year of life). The female toads usually do not mate until they are three years old. It was also found that the males did not grow during the breeding season and that those who courted for the first time in their second year of life became considerably larger.
The breeding cycle is long, beginning in coastal areas in early February, in mountainous areas from late March to early April and continues into July. You can hear the males' courtship calls almost only at night in the silent outriggers of open rivers. During this time, however, there are interruptions for days, which can also be triggered by floods, high tides, cold or windy weather, among other things. When the water level drops to a shallow, flowing stream, the courtship song is resumed. Two to three days before and after the full moon, the courtship calls are also very reduced. The males call from about 2 to 4 cm deep water, 1 to 2 m away from the bank, facing there and unobstructed by any vegetation. The females do not answer for about ten days.
The courtship song is a long musical trill of about 6 to 11 seconds duration, which begins gently with a slightly rising tone and then becomes evenly louder. At 15 ° C the tone is mainly 1.46 kHz and the trill time 44 per second. In addition, no call concerts are formed. The courtship song is very similar to the louder, rougher trills of the prairie toad and is reminiscent of the somewhat higher and longer call of the American toad ( Anaxyrus americanus ).
A very rapid series of chirping tones signals to a male that it has accidentally eaten up another male to mate (protest call). The trill is piercing, with a distinctive belly voice that makes it difficult to pinpoint the exact position of the toad. However, the singing quality of the protest call is almost the same as that of the courtship call, but is very different from the rough protest call of the prairie toad.
Hybridization
Male arroyo toads were observed in amplexus (clasps) with late-breeding female northern toads that produced severely malformed hybrid larvae that had already died in larval age. Small male northern toads also try to clasp female arroyo toads for breeding. It has not yet been observed whether this also creates hybrid larvae. As there are differences between these two species in the main breeding season, spawning grounds and larval behavior, such hybrid reproduction is very rare.
Spawn
Many more males than females can be found in the pools at the beginning of the breeding season. Reproduction takes place in water and is not promoted by rainfall, but a water temperature of over 11 to 13 ° C is clearly preferred. Female arroyo toads breed from 66 to 78 mm in length and usually avoid running waters until they are ready to spawn. Even from a greater distance they choose the courting male and approach him directly. Females ready to spawn can still be observed in mid-July, so spawning will take several weeks. The egg-laying takes place in the courtship area near the male and does not take longer than an hour. About 42 to 65 eggs (several thousand per female) are placed in about 40 egg packets in a gelatinous mass in two or three 3 to 10 m long, wildly intertwined egg strings on the 2 to 31 cm deep bottom of shallow, barely noticeable flowing water between Leaves, brushwood, gravel and mud spawned close together (about 35 eggs over a length of 30 mm). They are deposited on fine sediment, the egg strings are never entangled around branches, roots or rubble and are fully exposed to light. The number of eggs varies greatly from person to person, it ranges between 2100 and 10,300, but mostly around 4,700. The egg shell, filled with water, measures 4.4 to 5.3 mm in diameter and is relatively firm and clear. The Vitellus is 1.2 to 1.6 mm in size, black above and white or gray below. The upper egg pole is dark, the lower one light. The spawning is endangered by drying out or flooding of the rivers.
Larval stage
At a water temperature of 12 to 16 ° C, the larvae hatch from the beginning of June 4 to 6 days after they have laid their eggs, and they remain attached to it for another 5 to 6 days until the egg shell has dissolved. After hatching, the tadpoles stay together for about 15 to 18 days. The total body length is 17 to 34 mm, and the outer lower lip is one-third to one-half longer than the inner one. Their basic color is dark and pigmented on top with a matt gold color, dorsal more extensive dots. The eyes are also matt gold colored. Ventrally they are white to guano-colored and shimmer in a pink shade. Clear guano-colored spots can also be seen on the underside of the tail muscles. The tail membranes appear translucent. The larvae reach a maximum tail length of an average of 34 mm. So far no larval polymorphism has been found. The tadpoles enjoy no protection whatsoever in the water, but live hidden and, as very good swimmers, are quite able to cover a distance of around 2 to 4 m with one pull if disturbed in deep water. Otherwise they are considered to be true to their location and move a maximum of 5 cm with one train. The larvae colonize shallow, open watercourses from silt to coarse sediments, but prefer sand and gravel as well as locations under tree roofs, all aquatic vegetation is avoided. They feed on substrates, decompose detritus and ingest microorganisms from beneath the surface of fine sediments or between gravel. Macroscopic algae or aquatic vegetation are spurned.
metamorphosis
Metamorphosis occurs around 65 to 80 days after hatching , which lasts for at least ten days. The very different rainy seasons result in large time differences in the brood development, so you can see the young toads at the earliest from the end of April to the beginning of October at the latest, but mainly from late May to early July.
During the metamorphosis, the animals seek out shallow waters on open banks. When the tail is reabsorbed into a stub, they go ashore. The fore limbs begin to develop about two to three days before the tail is fully resorbed. The body size of the young toads after metamorphosis varies between 9 and 22 mm, but averages 12 to 15 mm, measured from the tip of the mouth to the cloaca . For the first three to five weeks, hundreds of them cavort on the sparsely overgrown sand and gravel banks of their home waters.
Juvenile stage
Juvenile toads live very hidden for a long time a few meters from their home shore, where they enjoy full sunlight during the day (soil temperature: 30 to 43 ° C) on sparsely vegetated sand or gravel banks. During windy or cool weather and at night they look for damp gravel pits. From a body length of about 20 to 25 mm (from mouth to cloaca) they begin to actively dig, become nocturnal and hide during the day in shallow caves or in the bank vegetation. After dusk they look for food in the riparian forests. From a body length of about 30 mm, which is reached within three to five weeks after the metamorphosis, they change their behavior and disperse in the immediate vicinity of flowing water. Shortly afterwards they colonize the adult habitats and remain active until the beginning of autumn. By the beginning of October, many of the young toads had reached a body length of 45 to 50 mm, and some began courting in the following spring.
A laboratory test showed that juvenile arroyo toads and northern toads ( Anaxyrus boreas ) grew at approximately the same speed in spatially separated groups of the same number of individuals. Without spatial separation, it was found that arroyo toads grew only half as fast and the northern toads grew at the same rate, and the latter ate about three times more crickets. This interaction has not yet been explored in nature.
Juvenile and pre-adult arroyo toads are mainly diurnal. They can be found from pools separated from the river up to several hundred meters away in hot, dry sand plains. In the late afternoon they become noticeably less, many dig backwards into small caves in the loose sand or gravel, others dig under larger rocks and still others use hoof prints of larger livestock or rodent burrows. Some also go back to the pools, where they rest among the active adults at night. The larger the young toads, the more active they become at night - this change usually takes place at the beginning of August. Towards the end of August you can rarely find the toads during the day.
Adult animals
Except during the breeding season, adult arroyo toads are mainly active at night and in the early morning hours. When the rivers carry very little water during the day or the rivers are only damp, they stay close together in groups of 10 to 15 individuals on the river bed, individually but also in silent branches, under overhanging river banks and in rodent burrows. Some bury themselves just below the surface of the earth, others up to half a meter deep in the sand. The hotter it gets on the summer days, the deeper they bury themselves in order not to dry out. After summer thunderstorms they escape the higher water level in the rivers or floods and can therefore also be found in large numbers on paved roads, which is why many of the toads are run over.
nutrition
Juvenile arroyo toads feed primarily on ants and small flies. In captivity, they also take crickets, although these are much larger. Adult toads eat other invertebrates, some of them larger, especially the nocturnal ant species Liometopum occidentale . For many weeks they form a column and always follow the same path, so that most toads return to the same feeding place at night. In 60 to 90 minutes they absorb 25% of their own weight in food. The feces of adult Arroyo toads normally have more than 95% of their mass Liometopum exoskeletons, on the surface it resembles that of the toad lizards ( Phrynosoma sp. ), Which only contains diurnal species of ants.
Distribution and habitat
Arroyo toads come to heights between 300 and 1000 m above sea level on sandy and gravelly river banks covered with Baccharis sp., Sour grasses (Cyperaceae), short grasses and herbs, river beds and river terraces up to several 100 meters wide in the coastal mountains and valleys of California and Lower California , from southern Monterey County to northwest Lower California, but also along larger rivers in the deserts of mountainous areas around San Gabriel and in San Bernardino County , in the highlands, as well as in grassland and scrubland. Rather seldom they can also be found on rivers with densely vegetated floodplains; in higher rivers they can be found more frequently on isolated Frémont poplars ( Populus Fremontii ), white alders ( Alnus rhombifolia ), willows ( Salix sp.), Oaks and plane trees . Very shallow and slowly flowing waters or gently sloping streams with a lot of boulders and larger rocks as well as large-scale deposits of fine sediments are preferred, which either carry water continuously and often form intertwined rivulets or dry out in midsummer. But they would have to keep water for about four to five months from spring to summer so that reproduction can take place (see below). If the rivers are largely flooded after a severe storm or a strong summer thunderstorm, you will look for them there in vain. They can also be found increasingly on irrigated fields. They can cope well with both light frost and temperatures above 46 ° C.
These distinct habitat differences indicate that much larger areas of California, which are now largely urbanized, were inhabited by arroyo toads, and that the ecological scope of this toad is underestimated by data collection of the now remaining populations.
District
Due to extensive seasonal migrations in the coastal areas of the highlands, arroyo toads are at times widely dispersed. While the largest adult males stay in the breeding area for the whole season, smaller males constantly migrate upstream and downstream and court for a few nights in different areas. Within a few years they cover two to three kilometers and are then so big that they mostly settle down. The adult females are particularly sedentary and move around with a continuous activity radius of a maximum of 50 meters. They almost always breed in the same area. Older juvenile and subadult toads make extensive migrations on the bank, the females disperse upstream to breed.
In the floodplain forest zone, arroyo toads dig shallow burrows during the breeding season, where they hide during the day. They prefer sandy soil that lies loosely over finer or coarser substrates. These buildings are mostly located in a relatively open environment, a preference for certain vegetation is not shown. During the dry season they dig their constructions closer to the shore, probably to keep their water balance balanced. Instead of digging, they move into small mammal structures.
Territorial behavior
Some of the adult males return to the same courtship area for many consecutive nights during their migrations. In females, on the other hand, pronounced loyalty to the territory and breeding territory was observed. If the water level changes during the breeding season, the mating location is adjusted accordingly. During the courtship the males sit still and hardly move, an action radius of 0.5 to 4 meters is very rarely exceeded. Any territorial conflict behavior during courtship has not yet been proven.
Breeding habitat
Deep or fast waters are unsuitable for breeding. On the other hand, calm, open edges of running waters are preferred, mostly on gravel and sand, less often on silt and coarser stones and extremely rarely on boulders and rocks. They remain protected under the canopy of trees or steep bank overhangs. The brood is almost never found in overgrown or stagnant water and puddles. Side channels of rivers and creeks are only used until the water stops there.
Summer rest and hibernation
Adult and pre-adult arroyo toads rest around August / September after the breeding season in order to prevent dehydration due to the high summer temperatures. The activity starts to decrease from the beginning of July. The juvenile and subadult animals, on the other hand, usually remain active even during these high temperatures and only calm down from the beginning of November.
Most adult toads go into hibernation ( torpor ) during their summer rest , so they remain relatively inactive from August at the earliest until March at the latest. Little is known about how they hibernate - they probably choose a slightly higher location to avoid possible flooding.
Predation and prey protection
Predators
Eggs and juvenile larvae of the arroyo toads have very few predators , for example the goblin fish ( Gambusia affinis ) and the red American crayfish ( Procambarus clarkii ) have been observed stealing and eating individual eggs. Even two-channel garter snakes ( Thamnophis hammondii ) took repeated eggs and choked the eggshells again. Free-swimming larvae are actively hunted by garter snakes ( Thamnophis sp. ) And eaten by introduced fish such as the green sunfish ( Lepomis cyanellus ) and Cottus asper . The number of feeding victims decreases when the young toads become nocturnal and disperse and subadult and adult toads are in the breeding season.
Again and again, adult arroyo toads are eaten by North American bullfrogs ( Rana catesbeiana ), as they are often found in the same area of distribution - in this case they are also considered the main predator. They find their male victims through their courtship calls and even hunt down couples located in amplexus . Individual bullfrogs can devour a large part of the local population. Occasionally two-lined and common garter snakes ( Thamnophis sirtalis ) hunt single sexually mature animals; but if they escape, they usually die later from their injuries. Except for shrews (Soricidae) and wedge-tailed plovers ( Charadrius vociferus ), no mammals or birds have been documented as predators.
Occasionally cannibalism has also been observed, so the adult toads occasionally eat the juvenile and pre-adult of their own species.
Prey protection mechanisms
Since the eggs and young larvae hardly have any predators, it is assumed that they are inedible for potential predators at this stage. There is apparently no discomfort in older larvae. Larvae prevent capture by garter snakes through efficient hiding places, behavior patterns and escape reflexes, but this is of little use against introduced sunfish (Centrarchidae). When disturbed, they arch against the surface of the water and dig into the deeper water. Green sunfish use this escape reaction by making a sideways arch and prey on the larvae in shallow water.
Since their color pattern is very similar to the environment, young toads are difficult to spot. So they remain motionless when a predator approaches. Subadult and adult toads hide very quickly in dense vegetation at night. During courtship, the males retreat underwater in case of danger and cover up to 25 meters. They do not adopt any specific posture when threatened by a predator, and no visible release of secretions from the parotid glands as a stress response has been observed.
Diseases and parasites
So far, no cases of disease have been reported among the wild populations. The juvenile toads caught in 1991 for laboratory breeding were all quickly killed by an epidemic of potty mushrooms (Chytridiomycota), while no unexplained deaths were known in the wild this season.
Spawn expelled into deeper and cooler water is often attacked by fungi. The larvae are often of cyst-forming metacercariae unidentified flukes infest (Trematoda), whose hosts are the birds. During metamorphosis, these cysts are concentrated in the groin area and, when the tail is resorbed, also on the coccyx . A small, unidentified tapeworm (cestoda) has often been discovered in the body's muscles . Harmful effects from these parasites have not yet been observed.
Thermal ecology
The reference to temperature is very important to understand the ecology of all organisms, especially in ectothermic animals. The body temperature measured in the cloaca of the arroyo toads is 17 to 37 ° C and thus slightly below the respective ambient temperature (air, soil or water temperature). While adults prefer temperatures of 16 to 21 ° C at night, juveniles prefer temperatures of 26 to 37 ° C during the day. The activities of the pre-adult animals increase very quickly after sunrise until in the late afternoon the temperature of the soil and air falls below the 25 ° C mark. Even under extremely hot conditions, they do not dry out, but rather a small amount of water when touched and thus keep your skin moist. The highest recorded body temperature of a juvenile arroyo toad is 37.2 ° C with a ground temperature of 47 ° C and an air temperature of 38.6 ° C.
Hazard and protection
Compared to earlier, the population density of arroyo toads has decreased significantly, often to the point of local extinction. Very dense populations in particular are now extinct. The number of populations reached a clear low in the early 1990s after an extended period of drought and several decades of disadvantageous agriculture and hydraulic engineering, but most of these populations have recovered considerably. With normally twelve adults per hectare , the population density is relatively low; on coastal rivers it often doubles, usually unevenly, and can therefore be compared ecologically with Anaxyrus microscaphus .
Changes in water level result in high spawn mortality. Both being stranded by rapids and being washed away by even slight flooding are commonplace. Both late rains and thus minor floods as well as hydraulic engineering such as the construction of dams can partially decimate the survival of the spawn and young larvae in the river areas.
The mortality rate among pre-adult animals appears to be very high, so it has been observed less and less for several decades. Likewise, cannibalism among individuals of this species contributes to this. Mainly because of human water and canal construction together with long, severe drought periods and unfavorable agricultural use, they were decimated by 65% in their breeding areas at the time between the 1950s and 1990s, and at the end of 1994 they were even listed locally as "critically endangered". However, since significant progress was made in hydraulic engineering and canal construction, populations were able to recover somewhat in the 2010s, especially in public areas. Currently, most of the populations live in isolation, restricted to both river source areas in front of reservoirs and narrow alluvial forest corridors along broad channels to dams, gravel pits, towns and military training areas. Today the arroyo toad is endangered and many populations have been wiped out in recent years. It is protected under the Endangered Species Act .
Taxonomy
In the first description in 1915, Charles Camp classified the arroyo toad as a subspecies of the very similar, eastern prairie toad ( Bufo cognatus ) and named it Bufo cognatus californicus . Due to external morphological differences between these two toads, George Sprague Myers refuted this taxonomic subordination in 1930 and gave it the species name Bufo californicus . However, the external distinguishing features did not appear to many herpetologists large enough to justify a position as a separate species. Since the arroyo toad differs from Bufo compactilis only in smaller features in pigmentation , Jean Linsdale in 1940 assigned it to this species again as a subspecies. Frederick Shannon (1949), however, did not consider the arroyo toad to belong to the species B. compactilis and placed them and Bufo microscpahus as subspecies of the woodhouse toad ( Bufo woodhousii ) because of their similarities . Due to its unique morphology, Robert Stebbins considered B. microscaphus in 1951 as a separate species with the two allopatric subspecies B. m. microscaphus and B. m. californicus .
Geological and hydrological events in the Young and Middle Pleistocene could best explain the descent and divergence of the Bufo microscaphus complex. Erik Gergus analyzed in 1998 on the basis of Allozymes the taxonomic relationship of the known three subspecies Bufo microscaphus microscaphus , B. m. californicus and B. m. mexicanus with each other. Ten of the 25 evaluated gene loci were different and B. m. californicus seven, in B. m. mexicanus three and in B. m. microscaphus has no alloenzymic autapomorphies . These allozyme differences supported the hypothesis of three different lines of evolution that ultimately led to the development of different species. Accordingly, the taxonomic names of these three species were Bufo californicus , Bufo mexicanus and Bufo microscaphus .
As with other genera of the frogs, the species of the Old and New World have diverged during the long period of continent separation . According to a cladistic analysis of the family tree of the frogs by Darrell Frost et al. in 2006 there was a revision of many genera. The nearctic species of the genus Bufo were placed in their own genus with the name Anaxyrus . This led to a number of new generic name / epithet combinations that also affected the arroyo toad and all of its close relatives in North America.
| author | Renamed to | Reason |
|---|---|---|
| Camp 1915 | Bufo cognatus californicus | Subspecies of the more eastern B. cognatus , as it is very similar to it |
| Myers 1930 | Bufo californicus | Survey in the taxonomic species status due to external morphological differences to B. cognatus |
| Linsdale 1940 | Bufo compactilis californicus | Subspecies to B. compactilis because of only minor differences in pigmentation |
| Shannon 1949 | Bufo woodhousii californicus | Subspecies of B. woodhousii because of similarities to B. microscaphus and B. woodhousii |
| Stebbins 1951 | Bufo microscaphus californicus | Elevation of B. microscaphus to species status due to its unique morphology; allopatric subspecies: B. m. microscaphus and B. m. californicus |
| Gergus 1998 | Bufo californicus | Survey in the species status because of the smallest allozyme differences between Bufo microscaphus , B. mexicanus and B. californicus , which prove their descent from different evolutionary lines |
| Frost et al. 2006 | Anaxyrus californicus | Recognition of the cladistics of Nearctic Bufo as a genus requires a new combination between genus name and epithet |
swell
- Charles L. Camp: Batrachoseps major and Bufo cognatus californicus, new Amphibia from Southern California . In: University of California publications in zoology . tape 12 , no. 12 , 1915, ISSN 0068-6506 , p. 327-334 .
- John D. Cunningham: Observations on the Natural History of the California Toad, Bufo californicus Camp . In: Herpetologica . tape 17 , no. 4 , 1962, ISSN 0018-0831 , pp. 255-260 .
- Lang Elliott et al .: The Frogs and Toads of North America. A Comprehensive Guide to Their Identification, Behavior, and Calls . Houghton Mifflin Harcourt, Boston, New York 2009, ISBN 978-0-618-66399-6 , pp. 180 f .
- Michael J. Lannoo (Ed.): Amphibian declines. The Conservation Status of United States Species . Berkeley, Los Angeles, London 2005, ISBN 0-520-23592-4 .
- George Sprague Myers: The Status of the Southern California Toad, Bufo californicus (Camp) . In: Proceedings of the Biological Society of Washington . tape 43 , 1930, ISSN 0006-324X , p. 73-77 .
- Robert C. Stebbins: Amphibians of Western North America . Berkeley, Los Angeles 1951, pp. 255-280 .
- Tracy I. Storer: A synopsis of the Amphibia of California. In: University of California Publications in Zoology . tape 27 . Berkeley, London 1925, p. 187-192 .
- Anna A. Wright, AH Wright: Handbook of Frogs and Toads. The Frogs and Toads of the United States and Canada . Comstock, Ithaca 1933, pp. 54-55 .
Individual evidence
- ↑ a b c d e f g h i j k l m n o Lang Elliott 2009. P. 180 f.
- ↑ a b c Sprague Myers 1930. pp. 73-77.
- ↑ a b c d e f g h i j k l m n o p q r s Wright & Wright 1933. pp. 54–55.
- ↑ a b c d e Stebbins 1951. pp. 255-280.
- ↑ a b Storer 1925. pp. 187-192.
- ↑ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af Samuel S. Sweet, Brian K. Sullivan: Bufo californicus Camp 1915. Arroyo toad . In: Michael J. Lannoo (Ed.): Amphibian declines. The Conservation Status of United States Species . Berkeley, Los Angeles, London 2005, ISBN 0-520-23592-4 , pp. 396-400 .
- ↑ Wilbur W. Mayhew: Biology of Desert Amphibians and Reptiles . In: George W. Brown jun. (Ed.): Desert Biology . tape 1 . Academic Press, New York, San Francisco, London 1968, ISBN 0-12-135901-8 , pp. 195-356 .
- ^ A b Brian K. Sullivan: Southwestern Desert Bufonids . In: Michael J. Lannoo (Ed.): Amphibian declines . The Conservation Status of United States Species . Berkeley, Los Angeles, London 2005, ISBN 0-520-23592-4 , pp. 237-240 .
- ^ Anna M. Goebel: Conservation Systematics: The Bufo boreas Species Group . In: Michael J. Lannoo (Ed.): Amphibian declines . The Conservation Status of United States Species . Berkeley, Los Angeles, London 2005, ISBN 0-520-23592-4 , pp. 210-221 .
- ↑ Jean M. Linsdale: Amphibians and reptiles in Nevada . In: Proceedings of the American Academy of Arts and Sciences . tape 73 , 1940, ISSN 0065-6836 , pp. 197-257 .
- ↑ Frederick A. Shannon: A western subspecies of Bufo woodhousii hitherto erroneously associated with Bufo compactilis . In: Bulletin of the Chicago Academy of Sciences . tape 8 , no. 15 , 1949, ISSN 0009-3491 , pp. 301-312 .
- ^ A b c Erik WA Gergus: Systematics of the Bufo microscaphus complex: Allozyme evidence . In: Herpetologica . tape 54 , no. 3 , 1998, ISSN 0018-0831 , pp. 317-325 .
- ↑ a b Darrel R. Frost et al .: The Amphibian Tree of Life. In: Bulletin of the American Museum of Natural History . tape 297 , 2006, ISSN 0003-0090 , p. 363 ( digitallibrary.amnh.org [PDF]).
Web links
- Anaxyrus californicus onthe IUCN 2013 Red List of Threatened Species . Posted by: Geoffrey Hammerson, Georgina Santos-Barrera, 2004. Retrieved February 3, 2014.
- Chants of the Arroyo Toad on californiaherps.com. Retrieved April 24, 2014
