Melanotaenia rubrivittata
Laser Red Rainbowfish
Species Summary
Melanotaenia rubrivittata, the Laser Red Rainbowfish, is a small, brilliantly coloured rainbowfish described in 2015 from the Wapoga River system of northwestern Papua Province, Indonesia. It was originally mistaken for M. praecox, described from the Mamberamo drainage roughly 100 km to the east, but genetic analysis showed the Wapoga population to be a distinct species.
Etymology
The species name rubrivittata combines the Latin ruber, red, and vittata, striped, referring to the red body stripes that distinguish it from the similar M. praecox.
Etymology compiled from C. Scharpf (2023), “Fishes of Sahul: An Etymological Survey (Part 6), the rainbowfishes (continued)”, Fishes of Sahul 37(1): 2006–2022, and etyfish.org.
Distribution & Habitat
Melanotaenia rubrivittata is known only from the Wapoga River system near Siewa, a former Freeport Indonesia mining exploration camp roughly 100 km northeast of Nabire, on the edge of Cenderawasih Bay. The type locality, about 130 km upstream at an elevation of only about 70 m, was a small, fully shaded pond some 12 m across and only about 30 cm deep, formed by flooding of the nearby Tirawiwa River, with a soft mud bottom under a layer of dead leaves; further specimens came from a small, closed-canopy forest stream 1.3 km away. The only other fishes recorded alongside it were the gudgeon Mogurnda wapoga and a few juvenile Glossolepis leggetti. Further specimens collected nearby in 2012 came from a small rainforest stream also inhabited by Melanotaenia rubripinnis and Chilatherina alleni. The Wapoga system is an important centre of freshwater fish endemism: every one of these rainbowfishes is known only from this region, except C. alleni, which also occurs in the Siriwo River drainage about 70 km to the southwest, and Mogurnda wapoga and the goby Sicyopterus erythropterus are likewise found nowhere else.
Description
A small rainbowfish, not much exceeding about 50 mm SL. Nuptial males are brilliant neon blue over the upper two-thirds of the body, with five narrow red stripes running between the scale rows, and a silvery white to pale pink belly. The first dorsal fin is blue; the second dorsal fin is blue with a red base and a broad red zone along its outer margin; the anal fin is bluish with a red base and red outer edge; and the caudal fin is red, fading to bluish or translucent towards the rear margin. Nuptial males can also flash a golden-orange stripe running along the middle of the back from the dorsal-fin origin to the snout. Females are much duller, lacking the vivid red fin markings, with only a blue outer margin on the second dorsal and anal fins.
Comparison with Similar Species
Melanotaenia rubrivittata is most similar to M. praecox, sharing a neon-blue ground colour, bright red markings on the median fins, small maximum size and broadly overlapping fin-ray and scale counts. However, M. praecox entirely lacks the red body stripes of male Melanotaenia rubrivittata, tends to be more deep-bodied (average 41% SL versus 38% SL in males), has a slightly shorter snout, and usually has fewer lateral scales (29–30 versus 32–33) and more transverse scales (usually 11 versus always 10 in the new species). Genetic data confirm the two as distinct, if closely related, sister species — curiously, mitochondrial evidence also points to old introgression between Melanotaenia rubrivittata and Chilatherina alleni, a New Guinea species of the unrelated genus Chilatherina.
Account compiled for Home of the Rainbowfish from G. R. Allen, P. J. Unmack & R. K. Hadiaty (2015), “Melanotaenia rubrivittata, a new species of rainbowfish (Melanotaeniidae) from northwestern Papua Province, Indonesia”, Fishes of Sahul 29(1): 846–859.
References
- Allen G.R. & S. Renyaan (2000) Fishes of the Wapoga River System. In: Mack A.L. and L.E. Alonso (eds.) A Biological Assessment of the Wapoga River Area of Northwestern West Papua, Indonesia. RAP Bulletin of Biological Assessment 14, Conservation International, Washington, DC. USA.
- Allen G.R., P.J. Unmack and R.K. Hadiaty (2015) Melanotaenia rubrivittata, A New Species of Rainbowfish (Melanotaeniidae) from Northwestern Papua Province, Indonesia. Fishes of Sahul 29(1): 846-859.