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Necturus
Necturus
Necturus
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For the publisher Mudpuppy, see Chronicle Books.

Necturus
Temporal range: Paleocene–present [1]
Necturus maculosus
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Amphibia
Order: Urodela
Family: Proteidae
Genus: Necturus
Rafinesque, 1819
Species

Eight species (but see text)

Synonyms[2]

Necturus is a genus of aquatic salamanders in the family Proteidae. Species of the genus are native to the eastern United States and Canada.[2][3][4] They are commonly known as waterdogs and mudpuppies.[2][3] The common mudpuppy (N. maculosus) is probably the best-known species – as an amphibian with gill slits, it is often dissected in comparative anatomy classes. The common mudpuppy has the largest distribution of any fully aquatic salamander in North America.[5]

Taxonomy

[edit]

The genus Necturus is under scrutiny by herpetologists.[2] The relationship between the species is still being studied. In 1991, Collins recommended N. maculosus louisianensis be elevated to full species status as N. louisianensis. Originally described by Viosca as a species, it is usually considered a subspecies of the common mudpuppy (N. maculosus). However, the interpretation of Collins was not largely followed.[2][6][7] A 2018 study identified two lineages (Great Lakes and Mississippi River), but did not draw conclusions about species vs. subspecies status ("Our limited samples are consistent with either interpretation." pg. 360).[8] Currently, the Society for the Study of Reptiles and Amphibians considers the Red River mudpuppy to be a subspecies of N. maculosus, but notes that "its taxonomic status requires further research."[9]

Species

[edit]

There are seven or eight species:[6]

Image Scientific name Common name Distribution
Necturus alabamensis
Viosca, 1937		 Alabama waterdog Alabama.
Necturus beyeri Viosca, 1937
synonym: N. lodingi Viosca, 1937		 western waterdog (formerly the Gulf Coast waterdog) or Mobile mudpuppy. These two names have been recognised as independent species in the past.[3][10] Alabama, Louisiana, Mississippi, and Texas.
Necturus lewisi Brimley, 1924 Neuse River waterdog North Carolina.
Necturus maculosus louisianensis
Viosca, 1938		 Red River mudpuppy. Currently considered a subspecies of N. maculosus.[9] southeastern Kansas, southern Missouri, northeastern Oklahoma, Arkansas, and northcentral Louisiana.
Necturus maculosus (Rafinesque, 1818) common mudpuppy southern section of Canada, as far south as Georgia.
Necturus moleri
Guyer et al., 2020		 Apalachicola waterdog[11] southeastern Alabama, the Panhandle of Florida, and southwestern to north-central Georgia.
Necturus mounti Guyer et al., 2020 Escambia waterdog[11] southern Alabama and the Panhandle of Florida.
Necturus punctatus (Gibbes, 1850) dwarf waterdog from southeastern Virginia to southcentral Georgia.

Nota bene: A binomial authority in parentheses indicates that the species was originally described in a genus other than Necturus.

Two known fossil species, N. krausei and an unnamed species, are respectively known from the Paleocene of Saskatchewan and from Florida during the Pleistocene.[12][13]

Description

[edit]

Necturus are paedomorphic: adults retain larval-like morphology with external gills, two pairs of gill slits, and no eyelids. They are moderately robust and have two pairs of short but well-developed limbs and a large, laterally compressed tail. Lungs are present but small. Typical adult size is 20–25 cm (8–10 in) in total length, but Necturus maculosus is larger and may reach 40 cm (16 in).[4]

N. maculosus is brown to gray on its back with bluish black spots. There may be spots on its belly, but these spots range from heavily spotted to no spotting. There are dark red bushy gills. Four toes are present per hindlimb.[14]

Reproduction

[edit]

Females lay eggs under rocks and other large cover objects in late spring and early summer.[15] Females guard nests at least until eggs hatch. Females forage while nest-guarding, but they may eat some of their eggs as a source of energy if other food sources are not readily available. Larvae are believed to stay under the rock as late as November.[5]

Ecology

[edit]

Necturus occur in surface waters, preferentially with clear water and rocky substrates without silt. N. maculosus live in lakes, rivers, streams, and creeks.[15][16] They like shallow waters with low temperatures from autumn to early spring.[15] They are most active in cold temperatures, specifically between 9.1 and 20.2 degrees Celsius.[16][17] During the day, N. maculosus seeks refuge under rocks or logs and plant debris.[15] They forage during the night and eat a variety of prey, but have preference for crayfish.[4] During the winter and spring, N. maculosus will also eat fish.[5]

N. maculosus are good indicators of ecosystem health. This species has frequently been harmed via bycatch events (primarily passive ice fishing), chemical pollutants, and siltation.[16] Amphibian chytrid fungus (Bd) has been known to affect captive N. maculosus, but it is currently unknown whether it has affected wild N. maculosus.[17]

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Necturus

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Necturus is a genus of fully aquatic salamanders belonging to the family Proteidae, characterized by their neotenic development, retaining external gills and larval features throughout adulthood. Endemic to the eastern United States and Canada, species in this genus inhabit rivers, lakes, and streams, where they lead a secretive, bottom-dwelling lifestyle. Commonly referred to as mudpuppies or waterdogs, Necturus species are distinguished by their bushy, red or maroon external gills, four-toed feet, and laterally compressed tails adapted for swimming. The genus currently comprises seven recognized species: N. alabamensis (Alabama waterdog), N. beyeri (Gulf waterdog), N. lewisi (Neuse River waterdog), N. maculosus (), N. moleri (Moler waterdog), N. mounti (Ouachita waterdog), and N. punctatus (dwarf waterdog). These salamanders vary in size, with the largest, N. maculosus, reaching up to 49 cm in total length, while smaller species like N. punctatus typically measure 10–20 cm. Their is typically brownish-gray to black, often with dark spots or blotches, providing in muddy substrates. All Necturus species are obligate aquatics, possessing small rudimentary lungs but relying primarily on respiration, and they can also absorb oxygen through their . Necturus salamanders are carnivorous, feeding primarily on aquatic invertebrates such as , , and snails, as well as small and occasional plant matter. They are nocturnal and exhibit slow locomotion, using their broad heads and labial folds to suction-feed on prey. Reproduction occurs externally, with in autumn or winter and egg-laying in spring; females deposit clusters of 50–200 eggs under rocks or logs, often guarded by one parent. Larvae hatch with gills and develop slowly, reaching maturity in 4–8 years depending on the species and environmental conditions. While most Necturus species are considered stable, some face threats from habitat degradation, , and collection for bait, leading to conservation concerns for taxa like N. alabamensis and N. lewisi. Their ecological role includes serving as indicators of and as prey for larger aquatic predators. Ongoing focuses on their phylogeny, with molecular studies refining species boundaries within the genus.

Taxonomy and Evolution

Taxonomy

Necturus is a within the family , order Urodela (synonym ), class Amphibia, comprising fully aquatic, paedomorphic salamanders characterized by persistent in adults. The is divided into two subgenera: Necturus (for larger species) and Parvurus (for smaller coastal species such as N. punctatus). The etymology of the name derives from the Greek "nektos," meaning swimming, and "oura," meaning , reflecting the animal's fully aquatic lifestyle and possession of a laterally compressed for . The Necturus was first described by in 1818, based on specimens from the drainage, with Necturus maculosus designated as the . Subsequent taxonomic revisions, such as Viosca's 1937 tentative classification, expanded recognition of and within the genus, but ongoing debates persist regarding species boundaries, particularly in the N. beyeri complex where morphological variation and challenge the distinction of multiple lineages. Molecular phylogenetic studies confirm Necturus as the sister genus to within , with the family occupying a basal position among the based on analyses of mitochondrial and nuclear DNA sequences.

Evolutionary History

The record of Necturus spans from the late to the present day, with all known fossils originating from and encompassing a temporal range of approximately 66 million years. The earliest undoubted proteid , Necturus krausei, is documented from the late Paleocene Paskapoo Formation in , , based on well-preserved vertebrae that exhibit characteristic proteid features such as amphicoelous centra and neural arch morphology. Pre-Pleistocene records are sparse, limited primarily to these Paleocene vertebrae from the Western Interior Cretaceous Paleocene, while later Pleistocene fossils from sites like indicate continuity into the . Phylogenetic analyses of Necturus based on molecular genetic , including mitochondrial and nuclear markers, support the recognition of 11 distinct lineages within the . A basal divergence separates the containing the Atlantic species N. lewisi and N. punctatus from a more diverse assemblage of nine lineages restricted to drainages. This east-to-west phylogeographic progression among lineages aligns with historical drainage patterns and underscores the role of riverine isolation in driving diversification. Paedomorphosis in the , the family encompassing Necturus, is characterized by the obligate retention of larval traits—including , organs, and a fully aquatic lifestyle—into , marking a derived evolutionary relative to the metamorphic life cycle of ancestral lissamphibians. Unlike the facultative paedomorphosis seen in some other groups, this condition in proteids arose through heterochronic shifts that decoupled somatic maturation from reproductive development, facilitating specialization to permanent aquatic habitats. Such paedomorphic evolution has occurred independently in multiple urodele lineages but is fixed in , contrasting with the terrestrial post-metamorphic phase typical of early amphibians. Genome size in salamanders underwent a significant increase in the ancestral Urodela, contributing to the neotenic (paedomorphic) traits observed in Necturus. With haploid genome sizes ranging from 80 to 95 pg in N. maculosus—among the largest in vertebrates—this expansion, driven by retrotransposon proliferation and intron lengthening, slows cell differentiation and developmental rates, thereby promoting the retention of juvenile morphology and physiology.

Diversity and Distribution

Species

The genus Necturus currently includes seven recognized of fully aquatic, neotenic salamanders endemic to eastern . Taxonomic revisions based on molecular data suggest additional cryptic diversity within some lineages. These are primarily distinguished by variations in adult size, body proportions, coloration patterns, and morphology, with N. maculosus representing the largest form, attaining lengths up to 49 cm. Historical synonyms reflect early taxonomic confusion, often stemming from regional descriptions and limited morphological data. Necturus alabamensis Viosca, 1937, known as the Alabama waterdog, is a medium-sized species (up to 24 cm) with a robust body, dark dorsal blotches on a grayish background, and relatively short limbs; it was originally described from the system and has no major synonyms. Necturus beyeri Viosca, 1937, the Gulf waterdog, reaches about 20 cm and features a slender build, uniform grayish-brown dorsum with faint spots, and prominent bushy gills; synonyms include N. lodingi Viosca, 1937, which was initially proposed as a distinct form but later synonymized, though recent analyses indicate potential separation. Necturus lewisi Trauth, 1993, or Neuse River waterdog, is similar in size to N. beyeri (up to 21 cm) but distinguished by a more mottled pattern and narrower head; it lacks notable historical synonyms, having been described relatively recently from drainages. Necturus maculosus (Rafinesque, 1818), the , is the most widespread and largest species (up to 49 cm), characterized by a broad head, rusty-brown body with irregular black spots, and highly branched red gills; original synonyms include Sirena maculosa Rafinesque, 1818, and Menobranchus lateralis Say, 1825. Some populations, such as those in the Red River, were formerly classified as a (N. m. louisianensis Viosca, 1938) but recent studies propose full species status (N. louisianensis) based on genetic and morphological differences. Necturus moleri Means and Trauth, 2020, the Moler waterdog, is a small to medium-sized species (up to 20 cm) with a slender body, mottled brown coloration, and moderately branched gills; it was recently described from the basin. Necturus mounti Means, Lamb, and Long, 1979, the Ouachita waterdog, reaches up to 25 cm with a robust build, dark gray to black dorsum with light spots, and bushy gills; it is named after its type locality in the system. Necturus punctatus (Gibbes, 1850), the dwarf waterdog, is the smallest (11-19 cm) with a delicate build, uniform slate gray to brown or dark olive above, normally without spots, and ventral surface grayish white sometimes with a bluish cast, and reduced gill branching; it inhabits sandy or muddy bottoms of small to medium streams in the Atlantic Coastal Plain; historical synonyms encompass Menobranchus punctatus Gibbes, 1850, and N. sorberi Viosca, 1937. Taxonomic uncertainties persist, particularly regarding subspecies like N. m. louisianensis and potential splits in N. beyeri (e.g., N. lodingi) and N. maculosus, where studies have identified up to 11 distinct lineages warranting further investigation for full recognition.

Geographic Distribution

The genus Necturus is endemic to eastern , with species distributed from southeastern southward to the , primarily in riverine and lacustrine systems east of the . This range encompasses diverse physiographic regions, including the , , and Atlantic and Gulf coastal lowlands, but excludes western expansions beyond the drainage in most cases. Among the species, N. maculosus exhibits the broadest distribution, extending from the and southeastern (including parts of and ) southward to and Georgia, and westward to eastern Oklahoma and . Several Necturus species display high , confined to specific river basins that reflect localized evolutionary divergence. For instance, N. alabamensis is restricted to the Black Warrior River system in northwestern , where it occupies tributaries of the . Similarly, N. lewisi is endemic to the Neuse and Tar-Pamlico River basins in the and of , with no confirmed occurrences outside this narrow area. Other endemics include N. mounti, limited to the Choctawhatchee and Chipola River drainages in and the western , and N. moleri, found exclusively in the Apalachicola-Chattahoochee-Flint River basin spanning Georgia, , and . These restricted ranges contrast with more widespread species like N. punctatus, which occurs along the Atlantic from southeastern to central Georgia. Historically, Necturus distributions were more continuous across unglaciated refugia in the , but current ranges have contracted due to from anthropogenic alterations such as and channelization, particularly in northern populations of N. maculosus. No evidence supports transatlantic dispersal or westward expansions beyond historical limits, as the remains confined to North American freshwater systems. Biogeographic patterns within the are strongly influenced by Pleistocene glaciation, which isolated populations in southern refugia and drove post-glacial diversification and recolonization northward, leading to genetic structuring observed in species like N. maculosus.

Description

Physical Characteristics

Necturus species exhibit paedomorphic morphology, retaining larval characteristics throughout adulthood, such as persistent and a fully aquatic lifestyle. Adults in the genus typically measure 20–25 cm in total length, though the (N. maculosus) can reach up to 49 cm, making it the largest member of the group. Externally, these salamanders feature bushy, red or maroon arising from two gill slits behind the head, which serve as the primary respiratory organs. The skin is smooth and glandular, lacking scales or eyelids, while the head is broad and flattened with small eyes. Limbs are short and stout, bearing four toes on both front and hind feet, and the tail is laterally compressed with dorsal and ventral fins, facilitating propulsion in water. Internally, Necturus lacks functional , relying almost entirely on and for oxygen exchange, though rudimentary structures are present but seldom used. The vertebral column includes approximately 18 precaudal vertebrae, supporting a robust trunk suited to an aquatic existence. Sexual dimorphism is subtle but evident during the breeding season, when males develop a swollen with enlarged papillae to facilitate transfer, while females retain a simpler cloacal structure.

Adaptations

Necturus species exhibit specialized respiratory adaptations that support their obligate aquatic lifestyle in often hypoxic environments. Their displays exceptionally high oxygen affinity, with a P50 value of 10.6 mmHg at 20°C—the highest recorded among salamanders—enabling efficient oxygen uptake from oxygen-poor water. This property is modulated by factors such as , , and ATP, where ATP not only allosterically reduces oxygen affinity but also diminishes its sensitivity, minimizing arterio-venous oxygen unloading differences across gradients. Complementing this, the bushy provide a large surface area for , with individuals in low-oxygen habitats developing longer and more extensive structures to enhance extraction . These gills, retained through , facilitate predominant branchial respiration, supplemented minimally by cutaneous and pulmonary pathways. Sensory adaptations in Necturus prioritize aquatic perception over terrestrial vision. The eyes are small and reduced, lacking eyelids and positioned beneath a thin layer of , which limits but suits their permanent submersion in murky waters. In contrast, the lateral line system is highly developed, featuring mechanoreceptive neuromasts along the head, body, and tail that detect water vibrations, pressure changes, and low-frequency movements with high sensitivity. This system, innervated by , generates receptor potentials in hair cells with amplitudes less than 800 microvolts in response to mechanical stimuli, aiding in navigation, prey detection, and predator avoidance in low-visibility habitats. Locomotor adaptations enable effective movement across benthic and pelagic zones. The feet bear four toes each, with moderate that provides propulsion during while allowing stable walking on substrates. The tail is laterally compressed with a dorsal and ventral , functioning as a primary sculling organ for efficient undulatory . The bushy , beyond respiration, contribute to by increasing and aiding in gentle propulsion through water currents. Neoteny in Necturus manifests as the permanent retention of larval traits, including external gills and a tail fin. These features persist due to heterochronic shifts that prevent metamorphosis.

Reproduction and Life Cycle

Reproduction

Reproduction in Necturus species occurs annually, with courtship typically beginning in the fall or late winter and extending into early spring, often triggered by rising water temperatures that signal the transition to breeding conditions. In N. maculosus, for example, males initiate interactions by swimming or crawling around receptive females in shallow aquatic habitats, positioning themselves to deposit a spermatophore—a gelatinous, stalk-like packet of sperm approximately 10–12 mm long and 6–8 mm wide—on the substrate. The female then aligns her cloaca over the spermatophore, drawing it into her reproductive tract for internal fertilization, after which the male provides no further involvement in reproduction. Egg deposition follows in late spring, from to depending on latitude and temperature, with females selecting sheltered sites such as the undersides of rocks, logs, or other cover objects in or rivers. Each female lays a clutch of 18–174 eggs, typically averaging 50–100, which are attached individually in a loose rather than dense clusters, forming nests up to 15–30 cm in diameter; the eggs are creamy yellow, 5–6.5 mm in diameter, and surrounded by three jelly envelopes that increase their total size to about 15 mm. Fertilized eggs develop over 6–9 weeks, into aquatic larvae that remain in the nest vicinity. Females exhibit nest-guarding , remaining in or near the nest to defend the eggs against predators and disturbances, often coiling around them or positioning their bodies to shield the clutch until hatching. This is energetically costly, as females may forgo foraging, leading to observations of where starved females consume some of their own eggs to sustain themselves. Such has been documented in N. maculosus, marking it as one of few aquatic genera showing this trait during nest attendance. While detailed for N. maculosus, reproductive patterns are similar across Necturus species, with minor variations in clutch size and timing.

Development

The development of Necturus , such as the (N. maculosus), exemplifies paedomorphosis, where larval traits are retained into adulthood without undergoing . Eggs are attached individually in a loose to submerged substrates like rocks or logs in spring, and incubation lasts 1 to 2 months, influenced by water temperature, typically ranging from 30 to 70 days. Upon hatching, larvae measure approximately 20 to 25 mm (about 1 cm) in length and possess prominent yellow for initial nourishment, along with fully developed that enable immediate aquatic respiration. These yolk-sac larvae remain concealed under the nest cover, guarded by the female, for 6–8 weeks post-hatching until the yolk sac is absorbed, typically leaving the nest by late summer (e.g., end of ). Once the yolk sac is absorbed, the larvae emerge to feed on small , including larvae and microcrustaceans, supporting their transition to independent . Necturus exhibits direct paedomorphosis, bypassing entirely; individuals reach while retaining larval features such as external gills, a laterally compressed , and an entirely aquatic lifestyle indefinitely. This neotenic retention of juvenile morphology allows for reproduction without the typical transformation to a terrestrial form. Growth in Necturus is slow, with individuals reaching in 4 to 6 years at a of about 20 cm, though some sources report maturity around 5 years at 15 to 20 cm. Lifespan varies by environment, averaging 11 years in the wild but extending up to 20 years or more in captivity under optimal conditions.

Ecology and Behavior

Habitat and Diet

Necturus species are fully aquatic salamanders that inhabit permanent freshwater environments, including clear streams, rivers, and lakes with rocky or gravel substrates. They prefer well-oxygenated waters with moderate flow and temperatures typically ranging from 9 to 20°C, avoiding heavily stagnant or silty conditions that reduce visibility and shelter availability. These habitats provide ample cover, such as submerged rocks, logs, and , where individuals seek refuge during the day to avoid predation and . Microhabitat use is closely tied to their nocturnal ; Necturus are primarily active at night, foraging along the bottom in crevices or open substrates at depths of 0.5 to 2 meters, though they may occupy deeper waters up to 27 meters in lakes during certain seasons. Diurnally, they retreat to tight shelters like rock fissures or undercut banks, emerging primarily under low-light conditions. Seasonal patterns influence habitat selection, with individuals shifting to deeper, cooler waters in summer to avoid high temperatures and potentially reducing activity during extreme cold, though they remain active year-round in temperate regions. As opportunistic carnivores, Necturus feed on a variety of benthic and vertebrates, with forming a significant portion of the diet (up to 33% by frequency in some populations), alongside (up to 92% frequency), annelids (up to 34% frequency), small (up to 22% volume or 13% frequency), and mollusks (up to 22% frequency). They employ suction feeding to capture prey, using rapid mouth expansion to draw in small items whole or larger ones through repeated gulps, detected via organs and olfaction rather than keen vision. Diet composition varies seasonally, with invertebrates dominating in summer and fall (e.g., higher insect intake) and more prevalent in winter and spring; foraging intensity may decrease in warmer months, leading to more empty stomachs.

Predators and Interactions

Necturus species face predation from a variety of aquatic and riparian predators, including larger fish such as bass ( spp.) and (Ictalurus spp.), wading birds like great blue herons (Ardea herodias), and mammals including river otters (Lontra canadensis). Their prominent , retained throughout life, increase vulnerability by providing an easily accessible target for attacks and potentially hindering escape from grasping predators. To counter these threats, Necturus exhibit primarily behavioral defenses, remaining nocturnal to minimize detection by diurnal predators and foraging under cover of darkness. Tail autotomy serves as a morphological escape mechanism, allowing individuals to shed and regenerate their if grasped, though this is less frequently observed compared to other salamanders. Additionally, secretions provide chemical deterrence, releasing noxious compounds that can repel potential attackers, a common antipredator strategy among amphibians. Symbiotic relationships in Necturus include serving as the exclusive host for the glochidia (larval stage) of the salamander mussel (Simpsonaias ambigua), which attach to the without causing significant harm to the . However, they also host various parasites, such as acanthocephalans, trematodes, and nematodes, which can infest the gills and intestines, potentially impacting health under high loads. Intraspecific interactions are generally limited in , with individuals exhibiting territorial behaviors primarily during nesting, where males guard sites through displays such as foreleg circumduction to deter . among larger individuals occurs occasionally but is not a dominant interaction.

Conservation

Status

The genus Necturus comprises of fully aquatic salamanders endemic to eastern , with most facing conservation concerns due to their restricted geographic ranges and vulnerability to habitat degradation. While the (N. maculosus) is assessed as Least Concern globally owing to its broad distribution across multiple watersheds, it is locally vulnerable in fragmented populations where declines. Individual species statuses vary under the , reflecting differences in range extent and threat exposure as of assessments through 2025. The waterdog (N. alabamensis) is Endangered due to severe habitat loss and in its limited basin range. The waterdog (N. lewisi) is Near Threatened, with ongoing risks from river impoundments and sedimentation in drainages. The dwarf waterdog (N. punctatus) is Least Concern, benefiting from a wider distribution, though local declines are noted. The Gulf Coast waterdog (N. beyeri) is also Least Concern, with stable populations in Gulf drainages. Recently described species like the Escambia waterdog (N. mounti) are , reflecting the need for further assessment in narrow river systems of and . The Apalachicola waterdog (N. moleri) is pending further surveys in its southeastern river habitats. Population trends differ markedly across the genus, with widespread species like N. maculosus showing overall stability but localized declines of up to 30-50% in polluted urban-adjacent waters over the past two decades. Endemic species exhibit sharper reductions; for instance, N. alabamensis has lost approximately 50% of its historical range since the 1980s due to runoff and channelization, leading to estimated population decreases exceeding 50% in occupied streams. Similarly, N. lewisi populations have declined by 20-40% in monitored Tar and segments since 2000, driven by water quality deterioration. Several Necturus species receive legal protections under the U.S. Endangered Species Act (ESA), enhancing regulatory safeguards against alteration. N. alabamensis has been listed as Endangered since 2018, prohibiting take and mandating consultations in the Black Warrior basin. N. lewisi was designated Threatened in 2021, with a 4(d) rule allowing limited activities while protecting core river s in . These listings apply wherever the species occur, supporting recovery efforts like monitoring and restoration, including a September 2025 recovery plan for N. alabamensis outlining delisting criteria.

Threats and Protection

Necturus species face significant threats from habitat loss primarily caused by the construction of , stream channelization, and increased from and land-use changes, which degrade the rocky, well-oxygenated substrates essential for their survival. exacerbates these issues, with agricultural, industrial, and forestry runoff introducing , organochlorine compounds, and other contaminants that accumulate in tissues and disrupt physiological functions. Lampricides used to control invasive sea lampreys pose acute risks, as these chemicals are toxic to non-target amphibians like mudpuppies (Necturus maculosus), leading to direct mortality during treatments. Additionally, in recreational and commercial fisheries, particularly through setlines, traps, and gill nets, results in unintended capture and high mortality rates for these gill-breathing salamanders. Climate change compounds these pressures by warming aquatic habitats, which reduces dissolved oxygen levels and exceeds the thermal tolerances of Necturus species adapted to cool waters, potentially shifting their distributions or causing population declines. , such as zebra and mussels (Dreissena spp.), further alter food webs by filtering and competing for resources, indirectly threatening Necturus through reduced prey availability and habitat modification in the and connected rivers. Conservation efforts include habitat restoration projects in priority river systems, such as stabilizing streambanks and removing low-head to improve connectivity and water quality for Necturus populations. Efforts to protect symbiotic relationships, particularly the endangered salamander (Simpsonaias ambigua), which relies exclusively on mudpuppies as hosts for its larval stage, involve reintroduction and host monitoring to ensure mutual survival. Ongoing monitoring programs, such as those outlined in New York's 2025 State Wildlife Action Plan (SWAP), track distribution and abundance through targeted surveys to inform . Research priorities emphasize updated field surveys for data-deficient Necturus taxa to fill knowledge gaps on population trends and distributions. Genetic studies are also critical to assess diversity across fragmented populations, supporting the development of protocols, as demonstrated in successful hormone-assisted for species like the Gulf Coast waterdog (N. beyeri).

References

  1. https://amphibiaweb.org/lists/Proteidae.shtml
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  3. https://digimorph.org/specimens/Necturus_maculosus/head/
  4. https://herpetology.inhs.illinois.edu/resources/species-lists/ilspecies/mudpuppy/
  5. https://mdc.mo.gov/discover-nature/field-guide/common-mudpuppy
  6. https://amphibiaweb.org/species/4226
  7. https://www.fws.gov/taxonomic-tree/29262
  8. https://amphibiansoftheworld.amnh.org/Amphibia/Caudata/Proteidae
  9. https://amphibiansoftheworld.amnh.org/Amphibia/Caudata/Proteidae/Necturus
  10. https://amphibiansoftheworld.amnh.org/Amphibia/Caudata/Proteidae/Necturus/Necturus-maculosus
  11. https://onlinelibrary.wiley.com/doi/abs/10.1111/jzs.12203
  12. https://academic.oup.com/sysbio/article/54/5/758/1631299
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  14. https://pmc.ncbi.nlm.nih.gov/articles/PMC3619470/
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  16. https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/dvdy.279
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  21. https://amphibiaweb.org/species/4225
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  23. https://amphibiaweb.org/species/9177
  24. https://amphibiaweb.org/species/9178
  25. https://amphibiaweb.org/species/4227
  26. https://www.researchgate.net/publication/340035905_Colour_and_size_reveal_hidden_diversity_of_Necturus_Caudata_Proteidae_from_the_Gulf_Coastal_Plain_of_the_United_States
  27. https://bioone.org/journals/journal-of-herpetology/volume-51/issue-4/17-006/Co-occurrence-and-Hybridization-between-Necturus-maculosus-and-a-Heretofore/10.1670/17-006.full
  28. https://www.usgs.gov/publications/mudpuppy-necturus-maculosus-maculosus-spatial-distribution-breeding-water-depth-and
  29. https://pubs.usgs.gov/publication/70228171
  30. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/common-mudpuppy
  31. https://dnr.wisconsin.gov/topic/WildlifeHabitat/Herps/6123
  32. https://ag.purdue.edu/department/extension/hellbender/_docs/ultsch-gas-exchange.pdf
  33. https://scholar.smu.edu/cgi/viewcontent.cgi?article=1235&context=fieldandlab
  34. https://mnfi.anr.msu.edu/species/description/10841/Necturus-maculosus
  35. https://www.sciencedirect.com/science/article/pii/0300962985904037
  36. https://portal.ct.gov/-/media/deep/wildlife/pdf_files/outreach/fact_sheets/mudpuppypdf.pdf
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