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Melanotaenia ericrobertsi
Melanotaenia ericrobertsi — from top: freshly captured male, about 85 mm SL; aquarium-acclimated male, about 70 mm SL; and two aquarium-acclimated females, about 60 and 50 mm SL, Suswa, West Papua — photo © Gary Lange

Melanotaenia ericrobertsi

Allen, Unmack & Hadiaty, 2014

Suswa Rainbowfish

Species Summary

Melanotaenia ericrobertsi is one of three closely related rainbowfishes from the Birds Head Peninsula of West Papua, Indonesia, described together in 2014. It was first collected in 1982 near Suswa village and originally included among the type series of M. irianjaya, but genetic evidence later showed it to be a distinct species, in fact more closely related to M. fasinensis from further down the same catchment.

Etymology

The species is named in honour of Eric Roberts, a pilot with Associated Mission Aviation, Papua Province, Indonesia, an aquarium-fish enthusiast who collected live specimens and is responsible for the introduction of this species to the aquarium hobby.

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 ericrobertsi is known only from the vicinity of Suswa village, in the foothills of the Tamrau Mountains at an elevation of about 176 m, roughly 120 km east of Sorong. The type locality is part of the extensive Kladuk River system, about 215 km upstream from the Karabra Estuary on the Birds Head’s south coast. The stream, 15–30 m wide at the type locality, flows through primary and secondary rainforest over gravel and sand, with fish concentrated mainly around log debris.

Melanotaenia ericrobertsi
Melanotaenia ericrobertsi — aerial view of the type locality near Suswa, Birds Head Peninsula — photo © Gerald R. Allen

Description & Comparison with Similar Species

Adult males have pronounced blackish zones on the front and rear mid-lateral parts of the body, a feature that separates Melanotaenia ericrobertsi at a glance from the very similar M. irianjaya, which lacks these dark zones and has a much broader white margin on the second dorsal fin. The two also differ in the shape of the male anal fin: in Melanotaenia ericrobertsi the longest rays sit at the front of the fin, an arrangement unusual for the genus, whereas in M. irianjaya the fin is more evenly rounded with the tallest rays in the middle. From its closer genetic relative M. fasinensis, which shares almost identical proportions and scale counts, Melanotaenia ericrobertsi is best told apart by those same dark mid-lateral zones, absent in M. fasinensis.

Account compiled for Home of the Rainbowfish from G. R. Allen, P. J. Unmack & R. K. Hadiaty (2014), “Three new species of Rainbowfishes (Melanotaeniidae) from the Birds Head Peninsula, West Papua Province, Indonesia”, aqua, International Journal of Ichthyology, 20(3): 139–158.

References