Nothobranchius krysanovi, Shidlovskiy, Konstantin M., Watters, Brian R. & Wildekamp, Rudolf H., 2010

Shidlovskiy, Konstantin M., Watters, Brian R. & Wildekamp, Rudolf H., 2010, Notes on the annual killifish species Nothobranchius rachovii (Cyprinodontiformes; Nothobranchiidae) with the description of two new species, Zootaxa 2724, pp. 37-57 : 45-49

Nothobranchius krysanovi sp. nov.

( Figs. 4 & 5 )

Nothobranchius rachovii , non Ahl, 1926: Watters et al., 2009

Holotype. MRAC A4-039-P-0078, male, 31.2 mm SL, Mozambique, 12 km S of Nicuadala in direction of Quelimane, Licungo River system, 17° 39.5' S, 36° 51.5' E, B. Watters, B. Cooper, R. Wildekamp, J. Jordaan, J. Bornman and J. Ippel, 6 April 2004.

Paratypes. MRAC A4-039-P0079-0080, 2 males, 24.3–26.0 mm SL, collected with holotype; MRAC A4-039-P-0079, male, 28.8 mm SL, 4 females 27.2–30.2 mm SL, Mozambique, 84 km from Caia ferry on road to Nicuadala, Lima River system, 17° 33.8' S, 36° 04.4' E, B. Watters, B. Cooper, R. Wildekamp, J. Jordaan, J. Bornman and J. Ippel, 5 April 2004.

Diagnosis. Morphology similar to N. rachovii . Nothobranchius krysanovi is distinguished from other species of the genus by the following combination of characters: males with bright colouration consisting of alternating light blue and orange-red oblique bars on body, dorsal and anal fins, and orange-brown caudal fin with orange subterminal and black terminal band. Female with faint brown oblique bars on posterior part of flanks. It can be distinguished from the other species of the subgenus Nothobranchius as follows: from N. furzeri by male colouration, higher number of dorsal fin rays (15–17 vs. 14 or 15); from N. kadleci by male colouration and shape of the frontal region, higher number of dorsal and anal fin rays (15–17 vs. 13 or 14 and 15–17 vs. 13 or 14) and from N. orthonotus by male and female colouration, and lower number of scales on the mid-longitudinal series (27–29 vs. 28–33).

Nothobranchius krysanovi can also be distinguished from N. rachovii by its higher number of diploid chromosomes (2n = 18 vs. 2n = 16); and from N. pienaari by its much lower diploid chromosome number (2n = 18 vs. 2n = 34).

Description. Morphometric data are presented in Table 3. Robust Nothobranchius of medium size. Snout pointed, mouth terminal, directed slightly upward. Body laterally compressed and deep. Dorsal profile concave on head, convex from nape to end of dorsal fin; more convex in older males than in younger specimens. Profile of caudal peduncle nearly straight.

Supraorbital squamation G-type with frontal part partly covered with epidermal tissue. Frontal and central supraorbital neuromast systems fused and forming two distinct shallow grooves. Both lined with three shallow lobes at both sides of the groove. Posterior cephalic neuromast systems in two curved grooves.

Dorsal fin rays 15–17, anal fin rays 15–17. Scales on the median longitudinal line 27–29+3 on caudal-fin base, most with shallow pit with one neuromast. Transverse row of scales above pelvic fins 11, circumpeduncular scales 12. Pelvic fins short, not reaching origin of anal fin. Pectoral fins reaching to first pelvic fin rays.

Male: maximum size observed 31.2 mm SL. Body laterally compressed and deep. All unpaired fins rounded, dorsal and anal fin covered with epidermal tissue. Papillae on the dorsal and anal fin rays, tips projecting through epidermis. Opercular membrane projecting from opercle, distal edge slightly wrinkled.

Female: smaller than male, maximum size observed 30.2 mm SL. Body less deep than in male. Dorsal and caudal fins rounded, anal fin triangular, tip rounded, rays 3–7 longer and more rigid. Anal fin positioned more posteriorly than in male. No epidermal tissue covering dorsal and anal fins or papillae on rays. Opercular membrane not projecting from opercle.

Colouration. Live male (see Fig. 4 ): body colour iridescent light-blue. Scales with distinct orange-red margins. Margin of some scales on posterior part of body and caudal peduncle more distinct, forming oblique bars, lower end forward. Snout and head carmine-red to orange-red, throat orange-red. Back anterior to dorsal fin carmine-red or brown-red. Operculum with 2 or 3 orange-red oblique stripes. Projecting part of branchiostegal membrane red to orange-red. Iris yellow-bronze to gold with incomplete dark vertical bar. Caudal fin orange-brown in the inner three quarters followed by a lighter orange subterminal band and black margin. Dorsal fin bright blue with red or red-brown spots, larger in proximal part and smaller distally. Spots may merge into oblong markings across fin. Dorsal fin with narrow blue-white margin. Anal fin similar to dorsal fin with lighter iridescent blue distal part lacking spots. Ventral fins bright blue with dark red proximal spots. Pectoral fins transparent translucent red with wide blue-white margin. Iris golden with dark vertical bar. Live female (see Fig. 5 ): body colour grey-brown, darker on the back to silver on abdomen. Several faint brown oblique bars, lower end to front, on posterior part of flanks. All fins colourless. Iris bronze or gold with incomplete vertical dark bar.

Distribution and habitat. Nothobranchius krysanovi is known from ephemeral pools and swamps on floodplains in coastal lowlands of east-central Mozambique north of the lower Zambezi River (see Fig. 3 ). It is presently known only from the basin of Kwa-Kwa River and its tributaries. Water level in the habitats is subject to seasonal changes and generally the water disappears completely during the dry season. Grass vegetation is usually found near the habitat margins. Much of the swamps may be utilised by local inhabitants for the cultivation of rice. Aquatic vegetation may comprise Nymphea , Ottelia , Lagarosiphon and Utricularia species. Sympatric fish species observed are N. orthonotus , Clarias gariepinus , Ctenopoma multispine , Protopterus amphibius (Peters, 1844) and unidentified Barbus and cichlid species. Nothobranchius krysanovi has an annual mode of reproduction.

Etymology. The species is named in honour of Prof. Eugeny Y. Krysanov, a scientist at the Russian Academy of Science, who carried out cytological studies on Nothobranchius species, as well as the effects of radiation on their chromosomes in the Chernobyl area. The species name is pronounced “kree-sa-nofi”.

Figures

FIGURE 3. Distribution of Nothobranchius rachovii (diamond symbol), N. krysanovi sp. nov. (triangle symbol) and N. pienaari sp. nov. (square symbol). Red-filled symbols represent type localities. Note that individual symbols may represent multiple sites where such sites are in close proximity to one another. Question marks beside two of the diamond symbols indicate sites of populations of unconfirmed affinity.

FIGURE 4. Nothobranchius krysanovi sp. nov., male ~ 31 mm SL, topotype, not preserved; Mozambique: south of Nicuadala in the direction of Quelimane, Licungo River system (MOZ 04 - 10). Photograph: R. Wildekamp.

FIGURE 5. Nothobranchius krysanovi sp. nov., female ~ 27 mm SL, topotype, not preserved; Mozambique: south of Nicuadala in the direction of Quelimane, Licungo River system (MOZ 04 - 10). Photograph: B. Watters.