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Melanotaenia sikuensis
Melanotaenia sikuensis — holotype, male, 91.0 mm SL, Siku Creek, Birds Neck Isthmus, West Papua — photo © Bambang Dwisusilo

Melanotaenia sikuensis

Kadarusman, Sudarto & Pouyaud, 2015

Species Summary

Melanotaenia sikuensis is one of eight closely related rainbowfishes from the Birds Head region of West Papua, Indonesia, described together in 2015 on the basis of combined evidence: a cytochrome oxidase I (COI) gene phylogeny, genotyping at 12 microsatellite loci, and diagnostic morphological characters. The approach revealed a level of cryptic diversity in the region well beyond what traditional morphological survey alone had detected. It belongs to the ‘Southern Birds Head’ group, within the ‘Birds Neck’ species cluster genetically allied to M. angfa, M. parva, M. naramasae and M. rumberponensis.

Etymology

The species is named for Siku Creek, the type locality.

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 sikuensis is known only from the type locality, a small creek about 5 m wide flowing eastward to Cendrawasih Bay through a karstic landscape.

Description & Comparison with Similar Species

Live males and females are similarly coloured: overall yellow, with a continuous blue-violet mid-lateral stripe two to three scales wide from the pectoral region to mid-body, widening to three or four scale rows on the caudal section, and no margin stripe on the dorsal or anal fins. Melanotaenia sikuensis is distinguished from M. angfa and M. parva by the dorsal-fin origin sitting behind (not level with or ahead of) the anal-fin origin, a shorter caudal peduncle, and a thicker mid-lateral stripe on the caudal peduncle, and from its closest relative M. rumberponensis by a slenderer caudal peduncle, shorter pelvic fin and fewer gill rakers.

Melanotaenia sikuensis
Melanotaenia sikuensis — paratype, female, 77.6 mm SL, same data as the holotype — photo © Bambang Dwisusilo

Account compiled for Home of the Rainbowfish from M. F. I. Nugraha, Kadarusman, N. Hubert, J.-C. Avarre, R. K. Hadiaty, J. Slembrouck, O. Carman, Sudarto, R. Ogistira & L. Pouyaud (2015), “Eight new species of Rainbowfishes (Melanotaeniidae) from the Birds Head Region, West Papua, Indonesia”, Cybium 39(2): 99–130.

References