| Family: |
Zenarchopteridae (Internally fertilized halfbeaks) |
| Max. size: |
4.28 cm SL (male/unsexed); 7.25 cm SL (female) |
| Environment: |
pelagic; freshwater; depth range - 0 m |
| Distribution: |
Asia: Mangola River basin (Sungai Mangolo, Sungai Tawo-Tawo and Sungai Watumbasi) in Sulawesi Tenggara, Indonesia. |
| Diagnosis: |
Dorsal soft rays (total): 11-13; Anal soft rays: 14-17; Vertebrae: 37-39. Nomorhamphus sagittarius can be diagnosed from all congeners by the following combination of characters: lower jaw elongated; one to seven teeth along dorsal surface of extended portion of lower jaw (absent in some specimens); fins and ventral surface of lower jaw orange; absence of black fin pigmentation; base of the pectoral fin with a distinct black spot; a lanceolate, dorsally slightly curved spiculus in the male andropodium, its middle segments in contact with the distal tip of the third anal-fin ray; seven to ten segments proximal to spinae (mode eight); segments three to seven (mode three to five) of second anal-fin ray in males with a dorsal and a ventral row of ‘subsegments’ forming small squares and rectangles of different sizes, so that these segments seem to be subdivided; second anal-fin ray with an elongated fourth or fifth segment (mode fifth) in some males (78.6% of the adult male type specimens); and third anal-fin ray slightly constricted longitudinally, giving the appearance of two distinct rays, distal part of this ray is slightly curved ventrally to contact spiculus (Ref. 97329). |
| Biology: |
Collected from three streams (Sungai Mangolo, Sungai Tawo-Tawo and Sungai Watumbasi) in Sulawesi Tenggara, Indonesia. There are two sampling sites for Sungai Mangolo: one is about 6-8 m wide and 10-100 cm deep with a sandy and rocky bottom and clear water at the type locality near the Scout Camping Ground of the Forestry Department area; and the other one is about 5-7 m wide, 10-50 cm deep and moderate running with a few boulders and stones at this point, is covered by rain forest canopy and with murky water due to traditional gold mining in the area. Sungai Tawo-Tawo is about 3-5 m wide and 10-50 cm deep at the sample site and characterized by a sandy and gravel bottom and by clear water with much riparian vegetation. The Sungai Watumbasi is 1-3 m wide, 10-30 cm deep and characterized by a muddy-sandy bottom (Ref. 97329). |
| IUCN Red List Status: |
Endangered (EN); Date assessed: 16 January 2020 (B1ab(iii)) Ref. (130435)
|
| Threat to humans: |
harmless |
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