Description
Aneides niger is a moderately sized, robust, black salamander. Males have snout-vent lengths ranging from 68.8 - 85.7 mm while females range from 58.3 - 73.7 mm. They are morphologically similar to other Aneides flavipunctatus complex. As is diagnostic of Aneides species, the heads are large and laterally expanded behind the eyes, creating a triangular appearance. The head width in males ranges from 10.5 - 16.3 mm, while head length in females ranges from 8.9 - 10.9 mm. The jaws of A. niger are very strong and individuals tend to show conspicuous musculature behind their eyes. Nasolabial grooves are present (Reilly and Wake 2019).

Although Myers and Maslin (1948) reported 12 - 14 coastal grooves with some specimens having a partial groove above the groin in the southern range, Lynch (1981) reported 16 – 18 costal grooves with the majority of specimens having 17. The limbs are long and robust, with the hindlimbs being slightly longer than forelimbs. The adpressed limbs are separated by 2.5 – 4.0 costal grooves in males and 2.0 – 3.5 costal grooves in females. The digits are slender, long, and terminally expanded. The longest digit is a toe. The tails are robust and moderate in length, up to 80% of the snout-vent length. The tails are capable of regeneration (Reilly and Wake 2019).

Aneides niger is nearly identical in body size and shape to the other members of the Aneides flavipunctatus complex (A. flavipunctatus, A. iecanus, and A. klamathensis), but can easily be distinguished by A. niger having a uniform black coloration without spotting or speckling and by geography. Additionally, A. niger is distinguished from A. aeneus by its larger size, rounded rather than flattened head and body, more robust appearance, shorter limbs and digits, and black coloration. Aneides hardii is much smaller and less robust than A. niger. Aneides ferreus and A. vagrans are smaller and have a less robust but more prehensile tail, and longer digits and limbs than A. niger. Aneides lugubris is larger, has a lighter coloration, less robust but more prehensile tail, and longer limbs and digits than A. niger. Only A. lugubris occurs in sympatry with A. niger (Reilly and Wake 2019).

In life, adults have a uniform shiny black coloration across the entire body, lacking light spots and speckling. Occasional adults will have a small number of very small light spots (Myers and Mastlin 1948, Reilly and Wake 2019).

In juveniles, the dorsal and ventral surfaces are covered with small white dorsal spots and frosted with a net-like gradual saturation of brassy iridophores that are lost as they mature. Juveniles can be significantly lighter than adults, exhibiting black, grey or slightly green color beneath the spotting (Myers and Mastlin 1948, Reilly and Wake 2019).

Sexual dimorphism is present in A. niger as size differences between males and females. Males are on average 8.2 mm longer in snout-vent length than females. Male heads are on average of 2 mm wider than females. Male forelimbs and hindlimbs average 2 and 1.6 mm, respectively longer than female forelimbs and hindlimbs. Males also tend to have more prominent jaw musculature, and males have conspicuous mental glands (Reilly and Wake 2019). If adults have iridophores they are the same size as juveniles (Lynch 1981).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: United States

U.S. state distribution from AmphibiaWeb's database: California

View distribution map in BerkeleyMapper.

Aneides niger is restricted to the Santa Cruz Mountains on the lower San Francisco Peninsula in Santa Cruz, western Santa Clara, and eastern and southern San Mateo counties, California. The species is present from sea level to approximately 800 m. Aneides niger inhabits lowland and foothill forests in areas of high moisture, particularly heavily shaded, wet streamside habitat. Individuals are often found submerged in or in contact with water (Myers and Mastlin 1948, Reilly and Wake 2019).

Life History, Abundance, Activity, and Special Behaviors
Aneides niger have adaptions for climbing, with features that include long toes and a rounded prehensile tail. However, this species exhibits a semi-aquatic habitat choice and occupies a distinct environmental space than other Californian Aneides (Rissler and Apodaca 2007, Reilly and Wake 2019). Individuals are usually found in and around streams and seepages, requiring a high degree of moisture. It is the most semiaquatic of the Aneides species (Myers and Mastlin 1948, Reilly and Wake 2019).

The species is nocturnal, foraging at night (Myers and Mastlin 1948). The salamanders have been found at active during the day, but only under conditions of nearly 100% humidity, and were often found in contact with water. During the dry period they live underground (Stebbins and McGinnis 2012, Reilly and Wake 2019).

Aneides niger predominantly forages for small arthropods along the ground, including ants and termites (Myers and Mastlin 1948).

Reproduction of this species is terrestrial. However, courtship and breeding behavior is not very well-studied. It is assumed that females lay approximately 8 - 25 eggs in moist cavities below the ground in July - August and stay with the eggs until they hatch (Stebbins and McGinnis 2012).

Individuals in captivity have been recorded to bite one another. The bites leave large gashes in the skin due to their large teeth and strong jaws (Myers and Mastlin 1948).

Trends and Threats
At the time of the species elevation to full species (2019), A. niger had a recommended IUCN threat status of “Vulnerable”. The species has experienced population declines over the past few decades, with members of the formerly abundant species becoming more difficult to find. Multiple factors have contributed to this decline, including habitat disturbance and destruction, disease (pathogenic fungi), and climate change (becoming hotter and drier). Additionally, A. niger has low genetic diversity and a small range compared to A. flavipunctatus and A. klamathensis. Before the species was raised to a full species, the subspecies had a local status as “Priority 3 Species of Special Concern” from the California Department of Fish and Game. Survey work is needed to accurately determine the distribution, population size, and level of protection needed for long-term persistence (Reilly and Wake 2019).

Comments
The species authority is: Myers, G. S., Maslin, T. P. (1948). “The California plethodont salamander, Aneides flavipunctatus (Strauch), with description of a new subspecies and notes on other western Aneides. Proceedings of the Biological Society of Washington 61: 127–138.

Aneides niger was initially described as a subspecies of A. flavipunctatus, that could be identified based on its isolated distribution, microhabitat choice, and lack of light speckling (Myers and Mastlin 1948). Rissler and Apodaca (2007) first suggested that A. niger be elevated to full species based on their Maximum Likelihood analysis of ND4 and 12S mtDNA. However, the species was not officially elevated until Reilly and Wake’s (2019) BEAST analysis of ND4, cytB, and 12s mtDNA and 13 nuclear loci. Both studies found that A. niger represented the earliest speciation event within the A. flavipunctatus complex.

The species name, “niger”, meaning “black”, is a reference to the species’ shiny black color (Myers and Mastlin 1948).

In comparing different Aneides, Lynch (1981) found that A. niger had the lowest paedomorphism score, indicating that they retain fewer juvenile characters than any other species (Reilly and Wake 2019).

References

Lynch, J. F. (1981). ''Patterns of ontogenetic and geographic variation in the Black Salamander, Aneides flavipunctatus.'' Smithsonian Contributions to Zoology, (324), i-iv, 1-53.

Myers, G.S. and Maslin, T.P., Jr. (1948). ''The California plethodont salamander, Aneides flavipunctatus (Strauch), with descriptions of a new subspecies and notes on other western Aneides.'' Proceedings of the Biological Society of Washington, 61, 127-128.

Reilly, S.B., Wake D.B. (2019). ''Taxonomic revision of black salamanders of the Aneides flavipunctatus complex (Caudata: Plethodontidae).'' PeerJ, 7, e7370 . [link]

Rissler, L. J., and Apodaca, J. J. (2007). ''Adding more ecology into species delimitation: ecological niche models and phylogeography help define cryptic species in the black salamander (Aneides flavipunctatus).'' Systematic Biology, 56, 924-942.

Stebbins, R.C., McGinnis, S.M. (2012). ''Black Salamander Aneides flavipunctatus.'' Field Guide to Amphibians and Reptiles of California: Revised Edition. University of California Press, Berkeley, CA. [link]

Species Account Citation: AmphibiaWeb 2020 Aneides niger: Santa Cruz Black Salamander <https://amphibiaweb.org/species/9048> University of California, Berkeley, CA, USA. Accessed Sep 10, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 10 Sep 2024.

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