Nothobranchius pienaari, 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 : 49-51

Nothobranchius pienaari sp. nov.

( Figs. 6–8 )

Nothobranchius rachovii , non Ahl, 1926: Pienaar, 1968: 64

Holotype. MRAC A4-039-P-0081, adult male, 36.4 mm SL, Mozambique, Chokwe to Massingir road, 101 km SE of Massingir, Mazimechopes River system, 24° 24.7' S, 32° 46.6' E, B. Watters, R. Wildekamp, B. Cooper, J. Jordaan, J. Bornman and J. Ippel, 10 April 2004.

Paratypes. MRAC A4-039-P-0082-0083, two females, 35.8–38.5 mm SL, collected with holotype; MRAC A4-039-P-0022, one male, 30.8 mm SL; Mozambique, EN1 road from Vilankulo to Beira, SE of Mexungue, Gorongose River system, 20° 42.97' S, 34° 07.86' E; B. Cooper and R. Wildekamp, 31 March 2004; MRAC A4-039-P-0066-0072, 2 males, 5.3–38.0 mm SL, 5 females, 21.8–30.3 mm SL, Mozambique, road Nhamatanda (Vila Machado) to Inchope, 8 km SE of Dundo, Pungwe River system, 19° 40.7' S, 34° 46.7' E, B. Watters, R. Wildekamp, B. Cooper, J. Jordaan, J. Bornman and J. Ippel, 4 April 2004.

Diagnosis. Morphology similar to N. rachovii and N. krysanovi but distinguished from those by a slightly deeper body in males (see Table 3). Nothobranchius pienaari is distinguished from other species of the genus by the following combination of characters: male with colouration consisting of alternating blue-green to grey-green and dark red-brown to almost black scale margins and oblique bars on body and dorsal and anal fins, dark brown spotted basal half of caudal fin, and orange subterminal and black terminal band. It can be distinguished from the other species of the subgenus Nothobranchius as follows: from N. furzeri by male colouration and a slightly higher number of dorsal fin rays (14–16 vs. 14 or 15); from N. orthonotus by male colouration, lower number of scales on the mid-longitudinal series (26–31 vs. 28–33) and from N. kadleci by male colouration and shape of the frontal region, higher number of dorsal and anal fin rays (14–16 vs. 13 or 14 and 15–17 vs. 13 or14). Female distinguished by faint brown oblique bars on posterior part of flanks. Nothobranchius pienaari can also be distinguished from N. rachovii and N. krysanovi by a much higher number of diploid chromosomes (2n = 34 vs. 2n = 16 for N. rachovii and 2n = 18 for N. krysanovi ). It can also be distinguished from the karyotypes of N. furzeri and N. orthonotus that both have with 2n = 38 a higher number of diploid chromosomes ( Scheel, 1981).

Description. Morphometric data for N. pienaari are presented in Table 3. Robust Nothobranchius species of medium size. Snout slightly pointed, mouth terminal, slightly upward directed. Body laterally compressed and deep. Dorsal profile concave on head and convex from nape to end of dorsal fin, especially in older males. Upper and lower profile of caudal peduncle straight.

Dorsal fin rays 14–16; anal fin rays 15–17. Pelvic fins short, not reaching first anal fin ray. Pectoral fin reaching past first pelvic fin ray.

Scales on median longitudinal line 26–31+2 or 3 on caudal fin base, most with shallow pit in centre with one neuromast. Transverse row of scales above pelvic fin 11 or 12. circumpeduncular scales 12 or 13. Supraorbital squamation G-type. Anterior scales partly covered with epidermal tissue. Frontal and central supraorbital neuromast systems fused, forming two distinct, shallow grooves, both lined with three shallow lobes on both sides. Posterior cephalic neuromast system in two curved grooves.

Male: maximum observed size 38.5 mm SL. Body laterally compressed and deep. All unpaired fins rounded, dorsal and anal fin covered with thin layer of epidermal tissue. Papillae on all rays of dorsal and anal fins, projecting slightly from epidermis. Opercular membrane projecting from opercle, distal end wrinkled.

Female: smaller than male, maximum observed size 35.8 mm SL. Body less deep than male. Dorsal and caudal fin rounded, anal fin more posteriorly situated than in male, triangular, tip rounded, rays 3–8 longer, more rigid and branched only near tip. No epidermal tissue on dorsal and anal fins, and no papillae on rays.

Colouration. Live male (see Figs. 6 & 7 ): body colour light to dark blue-green to green scale centres. Scales with cherry-red to dark red-brown, sometimes almost black margins. These margins form narrow oblique bars, lower end forward. Bars on every second row of scales. Males of some populations appear very dark to almost black. Head grey-brown. Abdomen lighter grey-brown to pale pink, back olive-brown. Operculum with 3-4 dark red-brown oblique stripes. Throat pink to silver-grey depending on population. Projecting part of branchiostegal membrane brick-red or red-brown; may have narrow light blue edge. Iris bronze or golden with incomplete vertical dark bar. Proximal part of caudal fin silver-grey, with bronze sheen in some cases, and small dark brown markings between rays. In some populations these markings can merge and form irregular cross bars. Caudal fin margin black with, in most populations, a red to orange submarginal band. Width of this band varies between populations from broad to narrow or barely discernable. Dorsal fin light blue-grey with bronze hue and numerous dark red-brown or brown spots and stripes which may merge to form irregular bands across the fin rays. Submarginal part of dorsal fin green-grey or blue-grey with small dark spots. Dorsal fin with narrow white-blue margin. Anal fin blue-grey with irregular red-brown spots that may merge to bands. Markings are larger in proximal part of fins. Submarginal parts darker; may have narrow blue-white margin. Ventral fins blue-grey with red-brown markings in basal third. Pectoral fins colourless with blue-white margin. Iris bronze to golden with dark cross-bar. Nothobranchius pienaari is polymorphic in the colouration of its caudal fin. The orange submarginal band ranges from wide and very distinct to almost absent, depending on the population.

Live female (see Fig. 8 ): body colour mainly grey-brown, darker on the back and lighter on abdomen. Posterior part of flanks with several darker but faintly developed bars, inclined to the rear. Fins colourless. Iris bronze or golden with incomplete vertical dark bar.

Distribution and habitat. Nothobranchius pienaari occupies a vast area in the coastal lowlands of central and southern Mozambique and the adjacent part of northeastern RSA (see Fig. 3 ). It is known from temporary pools and swamps in the floodplains of several rivers flowing into the Indian Ocean south of the lower Zambezi River to the basins of the Chefu, Limpopo, and Mazimechopes Rivers in southwestern Mozambique and northeastern RSA. The Kruger National Park population in the RSA has a unique elevated position but is also within the drainage system of the Limpopo River ( Watters, 2006, Watters et al., 2009). Usually found in water-filled depressions in the floodplains of rivers and bordering swamps. Water depth is variable with the progress of the season. Aquatic vegetation may consist of Nymphea , Ottelia , Lagarosiphon and Utricularia species. Other fish species that may occur with N. pienaari are N. furzeri , N. kadleci , N. orthonotus , as well as non-annual fishes like Clarias gariepinus , Protopterus annectens and unidentified Barbus species ( Watters et al., 2009, Reichard et al., 2009, Reichard, 2010).

Etymology. Named after Dr. U. de V. Pienaar, retired biologist of the Kruger National Park, Republic of South Africa, and discoverer of Nothobranchius species, in honour of his efforts to protect and conserve these populations. The species name is pronounced “pea-nahri”.

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 6. Nothobranchius pienaari sp. nov., male ~ 35 mm SL, Mozambique: Mazimechopes River system, Chokwe to Massingir road (MOZ 04 - 13). Photograph: B. Watters.

FIGURE 7. Nothobranchius pienaari sp. nov., male var. ~ 30 mm SL. Not preserved; Mozambique: Gorongose River system, north of Save in the direction of Inchope (MOZ 04 - 2). Photograph: R. Wildekamp.

FIGURE 8. Nothobranchius pienaari sp. nov., female ~ 27 mm SL, topotype, not preserved; Mozambique: Mazimechopes River system, Chokwe to Massingir road (MOZ 04 - 13). Photograph: B. Watters.