Necturus beyeri alabamensis Hecht, 1958

Guyer, Craig, Murray, Christopher, Bart, Henry L., Crother, Brian I., Chabarria, Ryan E., Bailey, Mark A. & Dunn, Khorizon, 2020, Colour and size reveal hidden diversity of Necturus (Caudata: Proteidae) from the Gulf Coastal Plain of the United States, Journal of Natural History (J. Nat. Hist.) 54 (1 - 4), pp. 15-41 : 36-39

Necturus beyeri alabamensis Hecht, 1958 , in part

Necturus alabamensis Neill 1963 , in part and misidentification Necturus beyeri Neill 1963 , in part Necturus cf beyeri Bart et al. 1997 , in part Necturus (Parvurus) lodingi Dubois and Raffaëlli, 2012 , in part Necturus cf beyeri Apalachicola lineage Chabarria et al. 2017

Holotype. AUM 35617 ( Figure 15 ), a female collected 1 March 2002 in Big Creek near Cottonwood (31.01916 − 85.35017; WGS84 ), Houston County, AL, by Michael Buntin.

Paratypes. FLMNH 164246 (female); FLMNH 177187 (male) .

Diagnosis. Membership of this species in the genus Necturus is demonstrated by retention of external gills in adults, presence of pigmented skin, presence of four welldeveloped limbs, and reduction of digits on hind limbs to four toes. This species is unique in possessing a larval stage lacking numerous small white spots and an adult stage that is small in size, possesses dark dorsal and lateral spotting that is no larger than the size of the eye, and evidence of spotting on the mandible of the chin and lateral portion of the belly. Five sequence autapomorphies distinguish this species, all of which are ambiguous ( Chabarria 2008). This species is sister to the Mobile lineage + N. alabamensis + Pearl lineage + N. beyeri + N. maculosus ( Figure 1 ).

Comparisons. Necturus moleri has a juvenile stage that is pinkish grey and lacks white spotting, features that distinguish this species from the Mobile, Pearl, Pontchartrain and Western lineages of N. beyeri (numerous small white spots); N. alabamensis (light dorsolateral stripes); N. lewisi (middorsal light stripe); and N. maculosus (light dorsolateral stripes). Larvae of N. moleri are indistinguishable from those of N. mounti and N. punctatus . As adults, N. moleri typically possesses small (no larger than size of eye) dark spots, but might lack spots altogether, features that distinguish this species from the Pearl, Pontchartrain and Western lineages of N. beyeri and from N. lewisi (large dark dorsal spots). Adults of North Carolina populations of N. punctatus are similar in adult dorsal colour pattern to N. moleri while South Carolina and Georgia populations typically lack dark spots. Adults of N. alabamensis and N. maculosus frequently have large dark spotting on the dorsal and lateral surfaces (rarely seen in N. moleri ) but may retain faded evidence of the dorsolateral light stripe of the larval stage (never seen in N. moleri ). In life, the chin of N. moleri typically has small dark spots on the mandibles and the belly is dull white with a gradual change along the border between the immaculate white mid-venter and the light brown sides of the body. These features distinguish this species from N. mounti (typically with bright white chin and belly with sharp border between venter and sides of body).

Necturus moleri may possess a karyotype that includes 3 (Econfina Creek, Jackson Co FL, Choctawhatchee drainage; Guttman et al. 1990), 4 (Black Creek near Bruce, Walton Co FL, Choctawhatchee drainage; Sessions and Wiley 1985), or 6 (Juniper Creek, Marion Co GA, Chattahoochee drainage; Sessions and Wiley 1985) pairs of telocentric chromosomes. These characteristics of the karyotype represent a transition from an ancestral state lacking telocentric chromosomes ( N. punctatus and N. lewisi ) to a derived state of 6 pairs of telocentric chromosomes ( N. maculosus and the Western lineage of N. beyeri ; Sessions and Wiley 1985). Similarly, the Y chromosome changes from an ancestral condition with reduced heterochromatism ( N. lewisi and N. punctatus ) to a derived condition possessing extensive heterochromatism ( N. maculosus and the Western lineage of N. beyeri ), with N. moleri displaying intermediate levels of heterochromatism ( Sessions and Wiley 1985). Additional karyotypic data are needed from N. mounti and the Mobile, Pearl and Pontchartrain lineages to determine whether the above modifications of the presumed primitive Necturus karyotype are autapomorphies of N. moleri or are synapomorphies of all Gulf Coast Necturus .

Description of holotype. The type specimen measures 197 mm TOT, 134 mm SVL, and 63 mm TL; number of costal grooves is 16. The dorsum is a uniform dark greyish brown. The top of the head has numerous small dark brown punctations. The sides of the body are off- white, shading gradually to the dark dorsal colouration. The chin is light brown with a few dark brown punctations, especially along the mandibles. The gular fold is immaculate white, and the venter of the body is light brown with a few dark spots anteriorly, becoming immaculate shiny white at mid-venter, and shading gradually to a light smoky brown along the sides of the body. The holotype has the following values for measured morphological features – ED: 2.0 mm; EL: 0.9 mm; GD: 5.8 mm; GEL: 22.5 mm; GL: 24.9 mm; HWE: 17.2 mm; HWG: 28.9 mm; POL: 23.2 mm; REW: 2.2 mm; SL: 6.8 mm; SRE: 9.5 mm; SW: 6.6 mm; WBW: 27.5 mm.

Variation. Necturus moleri is of small size, with a largest male of 173 mm SVL (+ 73 mm TL) and a largest female of 134 mm SVL (+ 63 mm TL). Adult males average 126.4 mm SVL (n = 11) and females average 102.3 mm SVL (n = 15). Unlike the type specimen, most individuals of N. moleri are light brown to tan, often with a pinkish cast, and possess numerous small dark dorsal (75% of specimens) and lateral spots (71% of specimens). However, the species might lack spots (11% of specimens) or have bold dark spots (4% of specimens). In ventral colouration, most specimens (71%) have dark spots along the mandibles of the chin and the ventrolateral aspect of the belly but might have spots across the entire chin and belly (25% of specimens) or might be immaculate white (4% of specimens). Thus, the colouration of N. moleri is more variable than N. punctatus or N. mounti , the two species with the most similar size and colour pattern. Juveniles of N. moleri are uniform in colour at the smallest sizes but develop dark dorsal and lateral spotting at sizes above ca. 45 mm SVL. The modal value for costal grooves is 16 (n = 15), with 33% of specimens possessing 17 grooves.

Adult males (n = 6) have the following mean (and range) values for measured morphological features – ED: 1.4 mm (0.3–2.9); EL: 1.8 mm (0.1–3.8); GD: 3.8 mm (2.0–6.4); GEL: 19.1 mm (14.2–24.4); GL: 24.7 mm (18.9–32.1); HWE: 14.5 mm (10.5–17.6); HWG: 22.2 mm (17.5–29.7); POL: 18.7 mm (14.1–23.5); REW: 2.6 mm (1.9–3.8); SL: 7.2 mm (4.7–8.2); SRE: 9.3 mm (6.0–11.2); SW: 5.8 mm (3.6–8.5); WBW: 23.7 mm (17.0–35.5).

Adult females (n = 9) have the following mean (and range) values for measured morphological features – ED: 1.2 mm (0.1–2.9); EL: 1.4 mm (0.1–2.2); GD: 3.2 mm (2.2–5.8); GEL: 14.4 mm (7.9–23.2); GL: 19.4 mm (10.8–24.9); HWE: 11.3 mm (7.1–17.2); HWG: 17.6 mm (11.4–28.9); POL: 14.0 mm (7.4–22.5); REW: 2.1 mm (1.6–2.7); SL: 5.3 mm (3.1–6.8); SRE: 7.1 mm (3.7–9.5); SW: 4.6 mm (2.0–6.6); WBW: 16.7 mm (10.6–27.5).

Etymology. The specific epithet is a noun in the genitive case honouring Paul E. Moler for his tireless devotion to field herpetology of the southeastern United States and for recognising the need to improve our understanding of species richness within Necturus of the Gulf Coastal Plain. The recommended English common name is Apalachicola Waterdog.

Distribution and natural history. This species is restricted to the Apalachicola, Chipola, Choctawhatchee/Pea, Econfina, and Ochlockonee drainages of Alabama, Florida, and Georgia ( Figure 16 ). No life history study has been performed on this taxon, but features are likely to be similar to those of N. mounti .

Figures

Figure 1. Geographic distribution and phylogeny of six mitochondrial lineages (boldface) of Gulf Coast waterdogs typically assigned to Necturus beyeri. Tree is rooted by N. punctatus and paraphyly of N. beyeri is shown by inclusion of N. alabamensis and two lineages of N. maculosus. Phylogenetic construction and lineage names are from Chabarria et al. (2017). Drainages for each lineage are Apalachicola lineage – Apalachicola,Chipola, Choctawhatchee,Econfina, Ochlockonee, and Pea Rivers; Escambia lineage – Blackwater, Escambia (Conecuh in Alabama), Perdido, and Yellow Rivers; Mobile lineage – Dog, Escatawpa, Fish, Mobile, Pascagoula, and Biloxi Rivers; Pearl lineage – Pearl and Wolf Rivers; Pontchartrain lineage – Amite, Bayou Bonfouca, Bayou Lacombe, Blind, Tangipahoa, Tchefuncte, and Tickfaw Rivers; Western lineage – Calcasieu, Cedar Bayou, Old, Neches, Sabine, San Jacinto, and Trinity Rivers.

Figure 15. Photo of dorsum (a) and venter (b) of type specimen of N. moleri (AUM 35617; Houston County, AL; photos by Craig Guyer).

Figure 16. Distribution of localities of specimens assigned to N. moleri. Open circle is approximate location of type specimen.