New Rivulus killi named

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Yet another new species of rivulid killifish in the subgenus Melanorivulus has been described, this time from the Paran River drainage in central Brazil.

Wilson Costa named the new species Rivulus faucireticulatus in the latest issue of Ichthyological Exploration of Freshwaters.

Rivulus faucireticulatus is distinguished from all other Melanorivulus in having a unique colour pattern of a broad sub-basal red stripe on the dorsal fin in males, ventral portion of the head with a black reticulate pattern in females, caudal fin orange in the dorsal and ventral portions and yellow in the middle in females.

Rivulus faucireticulatus is named after the black reticulate colour pattern on the throat of females (from the Latin fauces, meaning throat and reticulatus, meaning with a net-like pattern), and is known only from the type locality in the Claro River (part of the upper Paran River drainage).

The small ponds that constitute the type locality are in an open area at an altitude of 787 m moderately exposed to sunlight. The water in the ponds was clear, pH 5.5 and at a depth of 1.5 m. All of the adults were collected close to the surface of the ponds, near emerging aquatic plants.

The same study also describes two poorly-known species of the subgenus Melanorivulus (R. pinima and R. vittatus) from the Claro River drainage.

Rivulus pinimaThis species is distinguished from other Melanorivulus in having a combination of: longitudinal rows of red dots along entire flank, black pigmentation on the head vestigial or absent, a longitudinally elongate white mark above the caudal spot in females, the absence of bars on the unpaired fins, dorsal and anal fins rounded in males, 34"37 scales in longitudinal series and 9"10 scales in the transverse series.

Rivulus pinima is found in shallow parts of streams with clear and slightly acid (pH 6.0"6.2) water.

Rivulus vittatusThis species is distinguished from other Melanorivulus in having a combination of: broad chevron-like red bars on the flanks in males, dark pigmentation concentrated on middle of posterior portion of head and on humeral region, dorsal and anal fins pointed in males, 31"34 scales in longitudinal series and a E-patterned frontal squamation.

Rivulus vittatus is found in shallow creeks and lagoons close to small rivers that have clear, slightly acid (pH 6.0) water.

Practical Fishkeeping was unable to obtain images of the species for reproduction.

For more information, see the paper: Costa, WJEM (2007) A new species of Rivulus from the Claro river drainage, upper Paran river basin, central Brazil, with redescription of R. pinima and R. vittatus (Cyprinodontiformes: Rivulidae). Ichthyological Exploration of Freshwaters 18, pp. 313"323.