Melanotaenia wokamensis
Wokam Rainbowfish
Species Summary
The Aru Archipelago, a cluster of islands on the shallow continental shelf between New Guinea and northern Australia, was largely overlooked by ichthyologists for a century after Dutch collectors first sampled its rivers in 1907–09. Aquarium enthusiast Heiko Bleher brought Aru rainbowfishes to hobbyist attention after visits in 2004 and 2007, and two expeditions in 2013 (organised by Gerald Allen, Mark Erdmann and colleagues, with genetic work by Peter Unmack) revealed the islands to be an unexpected hotspot of rainbowfish speciation: seven species in all, most found nowhere else. Melanotaenia wokamensis belongs to the Aru ‘Goldiei’ group, most similar to M. kolaensis of neighbouring Kola Island.
Etymology
The species name wokamensis is a suffix denoting place, referring to Wokam Island, Aru Islands, Maluku Province, Indonesia, the type locality.
Etymology compiled from C. Scharpf (2022), “Fishes of Sahul: An Etymological Survey (Part 5), the rainbowfishes (continued)”, Fishes of Sahul 36(4): 1968–1992, and etyfish.org.
Distribution & Habitat
Melanotaenia wokamensis is known only from three tributaries of Sungai Tunguwatu on western Wokam Island: narrow (3–5 m wide) limestone channels through rainforest, prone to flash flooding after heavy afternoon rain, where the species was most common in deep pools below cascades and small waterfalls.
Description & Comparison with Similar Species
Live males are light blue above with metallic reflections, a dark blue mid-lateral stripe bordered by bold, relatively broad red-orange stripes, and a bright blue patch behind the pectoral fin; the second dorsal and anal fins are blue with a broad reddish outer margin. It differs from its closest relative M. kolaensis in these brighter, wider red-orange stripes flanking the dark mid-line (M. kolaensis lacks them, showing a plain white to pale blue stripe instead), and from both M. picta and M. senckenbergianus in usually having fewer and larger scales (10 transverse rows, 33–34 lateral scales, versus 11–12 and 35–36 respectively). Unlike the otherwise slender Aru ‘Goldiei’ group, young Melanotaenia wokamensis under 50 mm SL are already noticeably deep-bodied.
Account compiled for Home of the Rainbowfish from G. R. Allen, R. K. Hadiaty, P. J. Unmack & M. V. Erdmann (2015), “Rainbowfishes of the Aru Islands, Indonesia with descriptions of five new species and redescription of M. patoti Weber and M. senckenbergianus Weber”, aqua, International Journal of Ichthyology, 21(2): 71–106.
References
- Allen G.R., R.K. Hadiaty, P.J. Unmack and M.V. Erdmann (2015) Rainbowfishes (Melanotaenia: Melanotaeniidae) of the Aru Islands, Indonesia with descriptions of five new species and redescription of M. patoti Weber and M. senckenbergianus Weber. aqua, International Journal of Ichthyology 21(2): 66-108.