Sciency Thoughts: Two new species of viviparous Halfbeaks from Sulawesi.

Saturday, 30 August 2014

Two new species of viviparous Halfbeaks from Sulawesi.

Halfbeaks (Zenarchopteridae) are small freshwater, estuarine and fully marine Bony Fish related to Needlefish and Flying FIsh. They are found across the Indo-Pacific Region, distinctive for their elongate lower jaws, which extend some way forward of the mouth. Members of the viviparous (live-young bearing) genus Nomorhamphus are found in hill streams and lakes on Sulawesi and the Philippines.

In a paper published in the Raffles Bulletin of Zoology on 9 May 2014, Jan Huylebrouck of the Zoologisches Forschungsmuseum Alexander Koenig, Renny Kurnia Hadiaty of the Museum Zoologicum Bogoriense and Ichthyology Laboratory at the Research Center for Biology of the Indonesian Institute of Sciences, and Fabian Herder, also of the Zoologisches Forschungsmuseum Alexander Koenig, describe two new species of viviparous Halfbeaks from Sulawesi.

The first new species described is named Nomorhamphus lanceolatus, meaning ‘lance-shaped’, a reference to the shape of the spiculus (a bone in the anal fin). Nomorhamphus lanceolatus is a yellowish-brown Halfbeak with a black spot on its pectoral fin. It’s lower jaw is short for a Halfbeak (confusingly making the Fish less lance-shaped than most of its relatives), and it reaches about 50 mm in length.

Nomorhamphus lanceolatus; Indonesia, Sulawesi: Sulawesi Tenggara; Wawolambo River, near the bridge on the road, between Kolaka and Kendari, 04°02'51.6"S 121°42'40.8"E. (A) male; (B) female. Renny Kurnia Hadiaty in Huylebrouck et al. (2014).

Nomorhamphus lanceolatus was found living in the Wawolambo River in the Sampara river basin, near a bridge on the Kolaka-Kendari road. The river was shaded by trees in the area where the Fish were collected, and about 7-9m wide and 50 cm deep.

The second new species described is named Nomorhamphus sagittarius, meaning ‘archer’ in reference to the shape of the Fish, which resembles an arrow. Nomorhamphus sagittarius is black in colour, with yellowish-orange fins reaching about 65 mm in length, with a strongly elongate lower jaw.

Nomorhamphus sagittarius; Indonesia, Sulawesi: Sulawesi Tenggara; Mangolo River, 03°58'56.6"S 121°34'05.5"E. (A) Male; (B) male, immediately after catching. Renny Kurnia Hadiaty in Huylebrouck et al. (2014).

Nomorhamphus sagittarius was found at two sites in the Sungai Mangolo (River Mangolo) and one site each in two of its tributaries, the Tawo-Tawo and Watumbasi. At the first Sungai Mangolo site the river was 6-8 m wide and 10-100 cm deep, with clear water and a sand and rock riverbed. At the second site the river was 5-7 m wide and 10-50 cm deep, with a rocky bed, overhung by the forest canopy and with water made murky by the activities of gold miners. At the Sungai Tawo-Tawo site the river is 3-5 m with and 10-50 cm deep, with clear water and a sand and gravel river bed, and much vegetation in the river. At the Sungai Watumbasi site the river is 1-3 m wide and 10-30 cm deep with a mud and sand bottom.