Limnophis bicolor GÜNTHER, 1865
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Higher Taxa | Colubridae (Natricinae), Colubroidea, Caenophidia, Alethinophidia, Serpentes, Squamata (snakes) |
Subspecies | |
Common Names | E: Bicolored Swamp Snake |
Synonym | Limnophis bicolor GÜNTHER 1865: 96 Limnophis bicolor — BOCAGE 1866: 47 Helicops bicolor — MONARD 1931: 102 Glypholycus bicolor — WITTE 1933: 86 Glypholycus bicolor — LAURENT 1947: 10 Limnophis bicolor — BROADLEY 1998 Limnophis bicolor — BROADLEY et al. 2003: 175 Limnophis bicolor — WALLACH et al. 2014: 384 Limnophis bicolor — CONRADIE et al. 2020 |
Distribution | SW Angola, S Zambia (Okavango and Zambezi drainage basins), E/S Democratic Republic of the Congo (Zaire), elevation 1000 - 1800 m. |
Reproduction | oviparous |
Types | Syntypes: BMNH 1946.1.14.53-54 |
Diagnosis | Diagnosis (genus): “Habit stout, cylindrical; form of the head as in Tropidonotus; tail rather short. Scales smooth, short, in nineteen rows; anal and subcaudals divided. A single anterior and two posterior frontals; loreal present. Maxillary teeth in an uninterrupted series, gradually increasing in size posteriorly, the last being distinctly larger than the preceding, and not grooved” (Günther 1865: 96; still valid fide W. Conradie, pers. comm. 12 July 2020). General description: The body is cylindrical and elongated, tapering gradually to a relatively short tail (males: 20–23% of total length, females: 16–20% of total length). Head is small and barely wider than the ‘neck’. The eye is medium to large with a round pupil. Dorsal scales smooth with no apical pits, in 19-19-17 scale rows; ventrals 130–143 males, 127–139 females; cloaca divided; paired subcaudals 50–61 males, 37–57 females. One (rarely two) preocular; the nasal suture intersects the 1st supralabial and not the loreal; two postoculars; temporals usually 1+2 (sometimes 1+3+3, 1+2+3, 1+3+4), the parietal rarely in direct contact with 6th supralabial (in 32% of specimens examined); supralabials usually 8–9 (rarely 7), 3rd and 4th (sometimes 3rd, 4th and 5th) contacting eye, 6th the largest; infralabials 9–10, first five (rarely first four) in contact with 1st chin shield. Maxillary teeth 26–31, slightly increasing in size posteriorly (Bogert 1940), Conradie et al. 2020). Colouration: The dorsum is uniform dark olive green to black, with 5–7 dark vertebral scale rows, often bordered by a broad pale brown stripe on either side of the body, 3–4 scale rows wide. Lateral edges of ventrals dark, joining the darker lower dorsal scales. Supra- and infralabials cream coloured, but dark brown to black-edged anteriorly, giving the appearance of a vertically barred lip. The venter varies from pale yellowish to reddish with no markings (Conradie et al. 2020). Size: Largest male 405 + 137 = 542 mm (TM 55550, Tchivinguiro, Angola); largest female 553 + 106 (t) = 660 mm (NMZB 10731, Ikelenge, Zambia). Bocage (1985) recorded a larger female with a total length of 760 mm (Conradie et al. 2020). |
Comment | Subspecies: Limnophis bicolor bangweolicus MERTENS 1936 has been elevated to full species status. Type species: Limnophis bicolor GÜNTHER 1865 is the type species of the genus Limnophis GÜNTHER 1865. Previously the genus was considered as a member of the Colubrinae. Habitat: Mostly associated with streams and lagoons in the higher plateaus of Angola, Zambia and DRC. Except for the two low-lying records with a degree of uncertainty (e.g. Bengo and Kinshasa), most of the known occurrences are at elevations between 1 000 and 1 800 m (Conradie et al. 2020). Distribution: for a map of the genus see Deepak et al. 2021: Fig. 1. Phylogenetics: for a phylogenetic analysis of Sub-saharan Natricine genera see Deepak et al. 2021. |
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