Adiniops rachovii Rachow, 1928 : 84

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 : 43-45

Adiniops rachovii Rachow, 1928: 84

( Figs. 1 & 2 )

Type locality. Beira, Portugiesisch-Ost-Afrika.

Material examined. Paralectotypes. ZMB 21389, 2 males, 31.0– 31.4 mm SL; Portugiesisch-Ost-Afrika, Beira (present Beira, Mozambique), 19o 49.8' S, 34o 54.1' E; deposited by A. Rachow, 2 June, 1926. (measured by H.O. Berkenkamp, lectotype not obtained on loan); MRAC A4-039-P-0023-0055, 11 males, 24.5–32.5 mm SL, 21 females, 22.1–26.9 mm SL, Mozambique, Beira, swamps alongside road from town to airport, Pungwe River system, 19o 49.8' S, 34o 54.1' E, B. Cooper and R. Wildekamp, 2 April 2004; MRAC A4-039-P-0056- 0 0 65, 10 males, 22.2–33.4 mm SL, Mozambique, 8 km SW of Tica, on road to Nova Almada, Muda River system, 19° 27.2' S, 34° 23.4' E, B. Cooper and R. Wildekamp, 2 April 2004.

Diagnosis. Nothobranchius rachovii is distinguished from other species of the genus by the following combination of characters: in males, a bright colouration consisting of alternating light blue and orange-red bars on the body and fins, orange-red head, and orange subterminal and black terminal bands in the caudal fin. 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 or15) and a lower number of scales on the mid-longitudinal series (26–28 vs. 28–30); from N. orthonotus by male colouration, lower number of scales on the mid-longitudinal series (26–28 vs. 28–33) and shape of the dorsal profile (convex vs. flat) and 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 or14). Females can be distinguished by the presence of a reflective light blue spot on all scales of the flanks (vs. few, irregularly dispersed light blue-green spots in N. furzeri and N. kadleci or frequent presence of brown spots on body and fins in N. orthonotus ). Nothobranchius rachovii can also be distinguished from all other species of the genus by its low number of diploid chromosomes (2n = 16).

Description. See Table 3 for morphometric data. A robust Nothobranchius species of medium size. Snout pointed, mouth terminal, slightly directed upward. Body laterally compressed and deep. Dorsal profile slightly concave on head, convex from nape to end of dorsal fin. In older males more convex than in younger specimens. Upper and lower profiles of caudal peduncle nearly straight.

Supra-orbital squamation G-type. Frontal part of supraorbital squamation partly covered with epidermal tissue. Frontal and central supraorbital neuromast systems, on top of the head, 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 pits.

Dorsal fin rays 15–17, anal fin rays 15–17 (18 in one male specimen), relative position of base of first dorsal-fin ray over base of second or third anal-fin ray. Pelvic fins short, not reaching origin of anal fin. Pectoral fins reaching to origin of pelvic fins. Scales on the median longitudinal line 26–28 plus 2 or 3 on caudal fin base, most with a shallow pit in centre. Transverse row of scales above pelvic fins 11 or 12, circumpeduncular scales 12 or 13.

Male: maximum size observed 33.4 mm SL. Body laterally compressed and deep. All unpaired fins rounded, dorsal and anal fin covered with epidermal tissue. Papillae on all dorsal and anal fin rays, projecting from epidermis. Tips of dorsal and anal fin rays not projecting from fin membrane. Opercular membrane projecting from opercle, distal edge slightly wrinkled.

Female: smaller than male; maximum size observed 27.1 mm SL. Body less deep than in male (depth 22.8–32.1 vs. 25.5–33.8 % SL). Dorsal and caudal fins rounded, anal fin triangular, tip rounded, rays 3–8 longer and more rigid. Anal fin positioned more posteriorly than in male (pre-anal length 62.8–67.9 vs. 58.4– 65.7 % SL). No epidermal tissue covering dorsal and anal fins or papillae on rays. Opercular membrane not projecting from opercle.

Colouration. Live male (see Fig. 1 ): general body colour iridescent light blue to pale blue-green or bluegrey, variable according to population. Head and throat orange, grading across operculum into light blue of body. Posterior margin of scales orange-red to brown-red, giving a strong reticulated appearance. Locally, scale margins are wider and merge to form chevron-shaped cross-bars, apex rearward. Dorsal and anal fins pale blue to light blue-grey, distally with orange-red to red-brown spots and stripes. Dorsal fin with narrow blue-white margin. Caudal fin pale blue to blue-grey with orange-red to red-brown spots and bars in the basal half, followed by a brown band grading into a wide orange subterminal band. Caudal fin margin black. Ventral fins light blue with some small red proximal spots. Pectoral fins pale translucent orange with light blue margin. Iris golden with dark vertical bar.

Live female (see Fig. 2 ): body colour olive grey-brown, frontal scales on flanks with iridescent light blue to silvery centers. All fins colourless. Iris bronze to golden with dark vertical bar.

Distribution and habitat. Known from temporary pools and swamps or water-filled depressions in the lowland floodplains of the lower Pungwe and lower Zambezi Rivers in eastern Mozambique ( Fig. 3 ). Usually found in water-filled depressions in the floodplains of these rivers. It is likely that N. rachovii also occurs in the lowland floodplains near the mouths of the Indian Ocean flowing rivers between the Pungwe and Zambezi Rivers. Water depth is variable and decreases as the dry season progresses, eventually drying out completely. Littoral vegetation usually consists of grasses, but in some cases grass occurs throughout the habitat. Aquatic vegetation may consist of Nymphea , Ottelia , Lagarosiphon and Utricularia species. Occasionally, the swamps are used by local inhabitants to cultivate rice. Nothobranchius rachovii is frequently found together with N. orthonotus , Clarias gariepinus (Burchell, 1822) , Ctenopoma multispine Peters, 1844 , Protopterus annectens (Owen, 1839) and unidentified Barbus species.

Figures

FIGURE 1. Nothobranchius rachovii, male ~ 33 mm SL, topotype, not preserved; Mozambique: Beira, road to airport (MOZ 04 - 3). Photograph: R. Wildekamp.

FIGURE 2. Nothobranchius rachovii, female ~ 26 mm SL, topotype, not preserved; Mozambique: Beira, road to airport (MOZ 04 - 3). Photograph: B. Watters.

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.