Glossolepis pseudoincisus [Lake Ifaten] (male+female) - photo© Buddy Jonkers

Glossolepis pseudoincisus

Allen and Cross, 1980
Tami River Rainbowfish

Species Summary
From October 1954 until May 1955, an expedition was made in Dutch New Guinea (West Papua) by the "Rijksmuseum van Natuurlijke Historie" in Leiden. The ichthyologist of the museum, Marinus Boeseman, was the leader of the expedition. His task was to provide a thorough knowledge of the fish fauna by intensively surveying as many rivers and lakes as possible in West Papua. This task was taken to heart and in a relatively short period many localities were visited, resulting in a rich collection for the museum in Leiden. This collection included many rainbowfishes, but a thorough study of this material and descriptions of all the new species was never made by Boeseman.

As part of his preparation for the revision of the rainbowfish family, Gerald Allen studied the Dutch collection of 1954-55 at the end of the seventies. He discovered no less than 4 new rainbowfish species, which he described in 1980 together with Norbert Cross. These species were Melanotaenia boesemani, Melanotaenia ajamaruensis, Melanotaenia japenensis and Glossolepis pseudoincisus. Glossolepis pseudoincisus was named pseudoincisus with references to its similar appearance and geographic proximity to Glossolepis incisus.

Distribution & Habitat
Specimens of G. pseudoincisus were collected by Boeseman in November, 1954 in an ox-bow lake of the Tami River, about 30 kilometres to the east of Lake Sentani. They are also known from Lake Ifaten, Lake Iwom and Lake Yaniruk.

Glossolepis pseudoincisus [Lake Ifaten] - photo© Gunther Schmida

In January 2001, Heiko Bleher collected a new Glossolepis rainbowfish from Lake Ifaten, an isolated crater lake situated in the mountains near Lake Sentani in West Papua. Lake Ifaten is about 300 metres above sea level. The lake has a diameter of around 250 metres. Water temperature 28°C, pH 9.0.

The fish look similar to Glossolepis incisus, but the scales are different (they're smaller and differently aligned). The new species is not as big as Glossolepis incisus; the body shape is more compact; the red coloration is more intense and the fin marking and shape is more pronounced. Also the Lake Ifaten Rainbowfish shows colour after three month of age - Glossolepis incisus needs nearly a year before they show proper colours.

The Lake Ifaten Rainbowfish has a very typical Glossolepis head. Very prominent at an age of one year, are the marks on the gill plate. A unique pattern of red lines that - so it appears - are drifting criss-cross. The females of the Lake Ifaten Rainbowfish are differently coloured. They have strong horizontal zigzagging yellow stripe colouration across the whole body. They also remain small - up to 6 cm total length.

Adrian R. Tappin
Updated August, 2015

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Glossolepis pseudoincisus