Dwarf water cobra
The dwarf water cobra ("Naja nana") is a small species of cobra found in the Democratic Republic of Congo (Katanga). The dwarf water cobra is venomous and is part of the subgenus "Boulengerina", which includes related species such as "Naja annulata", "Naja christyi", and "Naja melanoleuca". Taxonomy. "Naja nana" is classified under the genus "Naja" of the family Elapidae. It was first described by Collet and Trape in 2020 with two specimens from Lac Mai-Ndombe in the western Democratic Republic of the Congo. The generic name "Naja" is a Latinisation of the Sanskrit word "" (), meaning "cobra . The specific epithet nana" is Latin "nanus", feminine nana, in reference to its small size, up to only about , unlike Naja annulata and Naja christyi, the two other African species of semi-aquatic najas, the first of which reaches long and the second exceeds long (M. Collet, pers. obs.). Type and distribution. Holotype: MNHN-RA 2019.0042 collected in 2017 in by a fisherman from Lake Mai-Ndombe in the Democratic Republic of Congo. Paratypes: MNHN 2019.0043-0049, SDC NN.08-10 (10 specimens), collected in 2017 by fishermen from Lake Maï-Ndombe near Bokebeni and neighboring villages. Description. With only two  specimens available, dissection was not attempted so the first and second characters of Vidian canal position and number of solid maxillary teeth were not checked. However there are at least three solid teeth on the right maxilla of the female and the fangs are not modified for spitting. The specimens have the 6th or penultimate upper labial high, one preocular, rostral much broader than deep, internasals shorter than the prefrontals and dorsal scales are highly polished. The male specimen has one anterior temporal, however, the female has the 6th upper labial fused with the anterior temporal and lower second temporal  on both sides. Abnormal fused head shields were observed in some species Naja (Boulengerina) nana belongs to the genus Naja by its characteristic posture of defense and its cephalic scaling including in particular the absence of loreal. It is characterized by the following combination of characters: (1) a predominantly aquatic way of life and the straight row arrangement of the dorsal scales, which distinguishes it from all other species of the genus Naja except Naja annulata and Naja christyi and places it in the Boulengerina subgenus; (2) a small size, at most about one meter, which distinguishes it from Naja  annulata and Naja christyi whose length reaches more than ; (3) a specific dorsal and ventral coloration, with the back of a black color more or less studded with small white or yellowish spots, the abdomen mostly whitish with each ventral scale more or less bordered posteriorly with black and the underside of the tail black, while Naja annulata is light brown with dark rings and Naja christyi is dark brown with transverse yellow lines to the front of the body and neither of these two species shows a ventral coloration similar to that of Naja nana; (4) usually 19 rows  of mid-length dorsal scales (rarely 17 or 18 in males and 18, 20 or 21 in females), instead of 17 in Naja christyi and 21 to 25 in Naja annulata; and (5) from 186 to 209 ventral, including 186 to 202 in males and 192 to 209 in females, instead of 206 to 221 in Naja christyi and 192 to 226 in Naja annulata. In the Boulengerina subgenus, Naja nana is easily distinguished from Naja multifasciata which has 15 to 17 rows of dorsals, 153 to 175 ventral and 30 to 39 subcaudals, instead of 19 to 21, 186  to 209 and 64 to 76 respectively at Naja nana. The five species of the Naja melanoleuca complex are very distinct, in particular by the oblique arrangement of their dorsal scales (straight in Naja nana) as well as by their much less aquatic way of life. Naja nana sp, on the other hand, is very similar to Naja annulata and Naja christyi by its morphology and its exclusively piscivorous diet. It is distinguished from these two species by the following characteristics: (1) a significantly smaller size, almost always less than one meter, with a maximum of instead of around in  Naja annulata and more than in several specimens of Naja christyi which have been kept at serpentarium of the antivenom center in Kinshasa (M. Collet, pers. obs.); (2) a specific coloration, especially dorsal, black spotted with white, instead of light brown with black rings all along the body in Naja annulata (or only on part of the body in the subspecies N. a. Stormsi (Dollo, 1886) from Lake Tanganyika), and uniformly dark brown with a few light beige transverse lines on the front of the body in Naja christyi; (3) a different number of rows of dorsal to mid-body  scales, usually 19 in Naja nana sp. Nov. (rarely 17 in males and 21 in females) instead of 17 in Naja christyi and 21 to 25 in Naja annulata; (4) a different number of ventral scales, from 186 to 209 in Naja nana (186 - 202 in males and 192 - 209 in females), instead of 206 to 221 in Naja christyi and 192 to 226 in Naja annulata. Size. LR2896 (male): snout-vent ; tail ; total = . Tail length is 20.23% of total length. Total length/tail length = 4.94 within the range of the male paratypes). LR2895 (female): snout-vent (longest  female paratype ); tail (longest female paratype ); total = (longest female paratype ). Tail length is 21.41% of total length (total length/tail length = 5.05 - slightly lower than the range of the female paratypes) DNA sequencing. Female specimen was sampled for DNA while still alive. Sequencing of the mtDNA strangely showed that it was not distinguishable from that of "N. annulata" (W. Wüster, pers. comm. 2021). Behaviour in captivity. A slim "Naja" species, that will swim and climb,but seems to prefer a terrestrial habitat although it will hunt and defecate in water where possible. The acclimatisation process for wild caught  specimens is critical to the captive success of the species, the general quality of the health of the animals from the Congo is highly variable and most of the imported samples come in to the importer in very poor condition. Specimens surviving the initial acclimatisation processwill readily take fish from early on in captive care. Once acclimatised many captive specimens have been converted onto a mainly rodent-based diet - however it is unknown if this will have an effect on the long-term health of the specimens, and therefore a varied diet is recommended. One case of cannibalism of a  conspecific snake is known. Captive breeding of this species has been successful within Europe, with multiple reports of captive breeding and incubation with varied success with neonate survival. The original breeding by Peter Pastor (2015 and pers. comm. 2020) produced 4 viable eggs after a successful mating of one of his two pairs. The eggs were relatively large, elongate, approximately 70 x 24 mm (estimated from a photograph of an egg next to a tape measure). Incubation at 29 °C (84 °F) was exactly 70 days (laid June 17, first hatching August 26).