Melanotaenia grunwaldi [Topo River] - photo© Gary Lange

Melanotaenia grunwaldi

Species Summary
Adult male Melanotaenia grunwaldi are yellow-brown dorsally on head and greenish brown on upper back, grading to whitish ventrally; blue midlateral stripe from eye to caudal-fin base, widest portion on caudal peduncle where it covers about two horizontal scale rows; narrow brass-coloured stripe between each scale row on upper two-thirds of side; longitudinal yellowish zone on side immediately above blue mid-lateral stripe, extending onto upper caudal peduncle, also yellow ventrally on caudal peduncle below blue midlateral stripe; diffuse bluish zone anteriorly on lower side beginning at level of lower pectoral-fin base, extending posteriorly to level of about tenth soft anal ray; yellowish stripe (with metallic reflections) behind eye extending across upper cheek and middle of operculum where punctuated posteriorly with small red spot; dorsal, anal, pelvic and caudal fins yellow, except broadly translucent whitish on base of second dorsal and distal margin of anal and caudal fins; pectoral fins translucent yellowish. Colour pattern of female similar to that of male except lacking yellow areas on body and fins.

Melanotaenia grunwaldi is a member of the "Goldiei" rainbowfish group that share a wide range of morphological and meristic features and lack notable differences, as would be expected for closely related species. Due to their great similarity, the species belonging to the "Goldiei" group are most reliably distinguished on the basis of genetic differences, colouration, and their geographically isolated distribution. The challenge with the "Goldiei" species group is that while they all have strong genetic differences and some clear colouration differences, morphological and meristic differences are minimal in most cases.

Lebki River Habitat - photo© Andreas Wagnitz

Distribution & Habitat
Melanotaenia grunwaldi is currently known only from three sites in the upper Wami River system, which rises in hills within about 15-20 km southeast of the coastal town of Nabire, in West Papua. These sites are located along the Nabire-Enarotali road, one at the Topo River, another in a nearby tributary, and the third at the Lebki River. The first two locations are about 10 km south of Nabire and lie at an elevation of about 193 m above sea level. The third is about 6 km farther inland at an elevation 116 m. Specimens were captured in moderately fast-flowing conditions over a rock and gravel bottom. Temperature and pH values of 25.0-26.3°C and 7.5-8.2 respectively were recorded.

Melanotaenia grunwaldi [Lebki River] - photo© Andreas Wagnitz

Remarks
Melanotaenia grunwaldi was named "grunwaldi" in honour of Norbert Grunwald, a well-known German aquarist who devoted much of his life to keeping rainbowfishes and for his many years of service in connection with the Internationale Gesellschaft für Regenbogenfische (IRG) and its journal Regenbogenfisch.

The very first specimens of Melanotaenia grunwaldi were collected in the Wami River system by G. R. Allen and H. Bleher in 1982. M. grunwaldi (Topo River) were first collected for the aquarium hobby in 2012 by Gary Lange and Johannes Graf. Further collections from the Pepaya River (tributary of the Topo River) and Lebki River were collected in 2015 by Hans-Georg Evers, Jeffrey Christian and Andreas Wagnitz.

Literature
Allen G.R., P.J. Unmack and R.K. Hadiaty (2016) The Goldiei group of rainbowfishes (Melanotaeniidae) from the Birds Neck Region of New Guinea (Papua and West Papua Provinces, Indonesia) with descriptions of five new species and recognition of Melanotaenia dumasi Weber. aqua, International Journal of Ichthyology 22(1): 1-32.

Adrian R. Tappin
June, 2016