Kiunga filamentosa
Filament-fin Blue-eye
Species Summary
Kiunga filamentosa is a tiny blue-eye of the Upper Fly River system in Western Province, Papua New Guinea, one of three species described in the 2024 revision of the genus Kiunga. Adults reach about 30 mm in standard length. Like its close relative K. auromarginata it has comparatively tall dorsal and anal fins and a high number of fin rays, but it is unique in the genus in that presumed males develop elongate, thread-like pelvic fin rays that extend well past the origin of the anal fin — the feature for which it is named. To date the species is known only from preserved material; its colour in life has not yet been documented.
Distribution & Habitat
Kiunga filamentosa is known only from two sites about 2.8 km apart along the Drimkas Road — a road built in 2018 — at 6.7 and 9.8 km west of the Fly River, roughly 25 km northeast of the town of Kiunga. The creeks, reached only because of the new road, are clear, slow-flowing lowland rainforest streams about 5 m wide and 1–1.5 m deep, with soft organic beds in the deeper pools and shallower gravel runs between them.
Description
A small species, 18–30 mm SL. The second dorsal fin has about 15–19 segmented rays and the anal fin 16–20, both moderately elevated, and there are 3–4 cheek scales — features shared with K. auromarginata and separating the two from the lower-count K. ballochi and K. bleheri. Kiunga filamentosa is set apart from all congeners by the filamentous pelvic fins of presumed males, which reach well beyond the anal-fin origin (this feature is absent, or damaged and not evident, in other specimens).
Etymology
The species name filamentosa is Latin for filamentous, referring to the filamentous pelvic fins of presumed males.
Etymology compiled from C. Scharpf (2024), “Fishes of Sahul: an Etymological Survey (Part 7), Pseudomugilidae and Telmatherinidae”, Fishes of Sahul 38(2): 2176–2189, and etyfish.org.
Remarks
The Drimkas creeks were first sampled in 2018 and reported in the 2020 review of the genus under the name K. ballochi; the 2024 revision showed the Drimkas population to be a distinct species. Genetic analysis places Kiunga filamentosa closest to K. auromarginata.
Account compiled for Home of the Rainbowfish from G. R. Allen, M. P. Hammer, P. J. Unmack & A. W. Storey (2024), “A remarkable radiation of five species in the genus Kiunga (Teleostei: Pseudomugilidae) from the Fly River system, Papua New Guinea with descriptions of three new species”, Fishes of Sahul 38(2): 2137–2157, with discovery history from P. K. Amick, M. Yarrao & A. W. Storey (2020), “A review of the genus Kiunga (Teleostei: Pseudomugilidae), with notes on distribution, potential environmental impacts and recommendations for research and conservation”, Fishes of Sahul 34(3): 1626–1636.