Melanotaenia flavipinnis (male) - photo© Gary Lange

Melanotaenia flavipinnis

Species Summary
Melanotaenia flavipinnis was described from 20 specimens collected from two creeks on Misool Island in the Birds Head region of western New Guinea. Colour of adult males is: head brownish dorsally and on snout; preoperculum yellowish to white; operculum pale blue with dark blue stripe crossing uppermost portion with silvery white patch immediately below; green on dorsal half of body; pale yellow stripe between each scale row of body; dark blue midlateral stripe on posterior half of body, initially one scale row in width, but expanding to two rows (midlateral and row just below) on caudal peduncle; dark blue stripe on upper operculum continued just above and behind pectoral-fin base, incorporating 2-3 midlateral scales and connected to previously mentioned stripe by row of pale blue scales with dark blue margins; three lowermost horizontal scale rows of side with mauve streak on centre of each scale; side of breast bluish, sometimes with pink blush; dorsal, anal and pelvic-fins yellow; caudal-fin translucent grey to brownish; pectoral fins translucent. The colour pattern of the females are similar to that of males except sometimes lacking prominent dark blue midlateral stripe, in which case this feature is mainly light blue.

Male paratypes from the nearby Gam River were generally similar in colour to the holotype, although they exhibit a slightly more yellowish hue on the dorsal half of the body with less yellow on the ventral half. In addition, the black midlateral stripe on the posterior body was uniformly two scales wide, rather than initially covering a single scale row.

Adult males are only slightly deeper bodied, and have slightly longer fin-ray elements than in females. The longest soft dorsal-fin rays of males are located in the middle portion of the fin, in contrast to that of females, which are situated anteriorly. In addition, the depressed first dorsal fin of adult males extends to the base of the second or third soft ray of the second dorsal fin, compared with the spine or first ray in females.

Distribution & Habitat
Melanotaenia flavipinnis is known only from the southeastern portion of Misool Island in two drainage systems, Gam River and Ifaupan Creek, which are separated by a distance of only 4 km. The type locality consists of a narrow (about 1-2 m wide), relatively shallow (to about 0.5 m depth) stream with very gradual gradients flowing through second growth forest, about 3.5 km upstream from the sea. The type specimens were mainly collected over sand and gravel bottoms.

Remarks
Gerald Allen (1982) described M. misoolensis from 23 specimens collected by a Dutch expedition in 1948. The specimens were located during a visit to the Zoological Museum in Amsterdam. Subsequent trips were made by Gerald Allen to the type locality in 1999 and 2002 with the goal of obtaining additional specimens as well as genetic samples and live photographs. The type locality at the Wai Tama (tributary of the Kasim River system) is situated in the northwestern portion of the island. During the 1999 trip numerous streams were sampled while circumnavigating the island, but only one other location yielded rainbowfish specimens, the Gam River in the southeastern portion, or approximately 40 km distance from the Wai Tama site. Initially, the fishes from both sites were identified as M. misoolensis. Although, they differed in colour pattern, most meristic and morphometric features were very similar. Genetic analysis by Peter Unmack indicated they were most likely a single species. The Gam River fish was also collected by Heiko Bleher at a nearby creek (Ifaupan Creek) in 2001. The distinctly different appearance of fish from the two locations and the opportunity to collect additional specimens from Ifaupan Creek in 2013 by H. Bleher, M. Erdmannn, and G. Allen, provided impetus for a re-examination of their status. Although the two main river systems containing Melanotaenia, the Kasim and Gam, originate relatively close (within 4-5 km) to each other in central-southern Misool, the two systems comprise well separated drainages, with the Kasim River flowing towards the northwest and the Gam River to the southeast.

Melanotaenia flavipinnis differs most notably from M. misoolensis, with regards to colour pattern, relative positions of the first dorsal and anal fins, and height of the anal fin. Although both species have a prominent dark blue midlateral stripe (at least in adult males), that of M. misoolensis is more irregular in appearance, consisting of a solid posterior section encompassing two scale rows (as opposed to 1-2 rows in M. flavipinnis), anterior section embracing about 4-5 scales and usually extending onto upper half of adjacent scale row below (vs. 2-3 scales in M. flavipinnis), and 2-3 isolated dark patches (each covering 1-2 midlateral scales and part of adjacent scale row above) between the anterior and posterior sections. Other consistent differences found in M. misoolensis include the predominately whitish or translucent dorsal and anal-fins that grade to pale yellow distally (vs. entirely yellow), whitish pelvic-fins (vs. yellow), large red spot on the operculum (vs. white spot), and lack of yellow colouration on the body.

Literature
Allen G.R., R.K. Hadiaty and P.J. Unmack (2014) Melanotaenia flavipinnis, a new species of Rainbowfish (Melanotaeniidae) from Misool Island, West Papua Province, Indonesia. aqua, International Journal of Ichthyology, 20 (1): 35-52.

Adrian R. Tappin
June, 2014