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Carangaria/misc (Various families in series Carangaria) >
Polynemidae (Threadfins)
Etymology: Polydactylus: Greek, poly = a lot of + greek, daktylos = finger (Ref. 45335); luparensis: The specific name luparensis is based on the Batang Lupar River in reference to the holotype locality. Local name of this species is Gemian.
Environment: milieu / climate zone / depth range / distribution range
Ecologie
; zoet water pelagisch; diepte 3 - 5 m (Ref. 83753). Tropical; 2°N - 1°N, 111°E - 112°E
Asia: Malaysia, Borneo. Currently known only from the mouth of the Batang Lupar River, Borneo, Malaysia (Ref. 83753).
Grootte / Gewicht / Leeftijd
Maturity: Lm ? range ? - ? cm
Max length : 72.0 cm SL mannelijk / geslacht onbekend; (Ref. 83753)
Korte beschrijving
Determinatiesleutels | Morfologie | Morfometrie
Dorsale stekels (totaal) : 9; Dorsale zachte stralen (totaal) : 13; Anale stekels: 3; Anale zachte stralen: 11. A species of Polydactylus that differs from all of its congeners by the following combination of characters: 8 dorsal-fin spines, first spine tiny, second spine very strong (its width more than 5 times of width of remaining spines); 13 second dorsal-fin soft rays; 11 anal-fin soft rays; 12 pectoral-fin rays, its length 22–24% (mean 23%) of SL, posterior tip not reaching a vertical through posterior tip of depressed pelvic fin; 6 pectoral filaments, fourth or fifth filament longest, its length 77–85% (mean 81%) of SL, posterior tip extending slightly beyond caudal-fin base; pored lateral-lined scales 67–75 (mean 71); lateral line unbranched, extending onto upper end of lower caudal-fin lobe; 6 scale rows above lateral line, 8 below; 14 gill rakers on upper limb, 18 on lower limb, 32 in total; occipital profile concave; posterior margin of maxilla extending considerably beyond a vertical through posterior margin of adipose eyelid; depth of posterior margin of maxilla 4–5% (mean 5%) of SL, greater than orbit diameter; well-developed swimbladder present; basal half of third to sixth pectoral filament white, becoming black distally. Polydactylus luparensis can be easily distinguished from all Indo-Pacific congeners by having the black distal half of the third to sixth pectoral filaments (whitish in the latter). Only two other taxa, Polynemus melanochir dulcis Motomura & Sabaj, 2002 and P. melanochir melanochir Valenciennes in Cuvier & Valenciennes, 1831, in the family Polynemidae have the black pectoral filaments (Motomura & Sabaj, 2002; Motomura, 2004b) (Ref. 83753).
Inhabiting turbid brackish water. The species is abundant in the river mouth especially from June to August and mainly caught by gill nets. Juveniles have also been observed in the same place (local fishermen, pers. comm.) (Ref. 83753).
Levenscyclus en paargedrag
Maturiteit | Voortplanting | Paaien | Eieren | Fecunditeit | Larven
Lim, P.K.A., H. Motomura and A.C. Gambang, 2010. Polydactylus luparensis, a new species of threadfin (Perciformes: Polynemidae) from the Batang Lupar River, Sarawak, Borneo, Malaysia. Zootaxa 2405:63-68. (Ref. 83753)
Status op de Rode Lijst van het IUCN (Ref. 130435: Version 2024-1)
Gevaar voor de mens
Harmless
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Estimates based on models
Fylogenetische diversiteitsindex (Ref.
82804): PD
50 = 0.5000 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00562 (0.00268 - 0.01179), b=3.06 (2.87 - 3.25), in cm total length, based on LWR estimates for this (Sub)family-body shape (Ref.
93245).
Trofisch niveau (Ref.
69278): 3.8 ±0.5 se; based on size and trophs of closest relatives
Weerstandsvermogen (Ref.
120179): Gemiddeld, minimale populatieverdubbelingstijd 1,4-4,4 jaar (Preliminary K or Fecundity.).
Fishing Vulnerability (Ref.
59153): High vulnerability (55 of 100).
