Microsternarchus brevis Cox Fernandes, Nogueira, Williston & Alves-Gomes, 2015
photo by Cox Fernandes, C.

 Family:  Hypopomidae (Bluntnose knifefishes)
 Max. size:  5.3 cm TL (male/unsexed); 5.32 cm TL (female)
 Environment:  pelagic; pH range: 4.01 - 5; depth range 0 - 2 m
 Distribution:  South America: Brazil.
 Diagnosis:  This species is distinguished by the following characters: short caudal filament 12.8-20.9% of TL; size of body small 3.75-5.32 cm SL; slightly inferior mouth 1.34-2.42 cm HL; pigmentation on body uniformly distributed along the entire area, including head; it also lacks a well delineated dark area on the pseudotympanum, where the anterior end of the posterior lateral line nerve branches with the dorsal ramus of the posterior lateral line nerve (Ref. 104297). Description: The electric organ occupies about 10% of greatest body depth and 1% from the snout to posterior end of anal fin; it is deep in the first 2/3 of he body, located above the proximal radials and is more visible over the last 1/3 of body above the end of the anal fin. The electrolytes appear to be large, consist of 1-2 bilateral pairs of columns rows parallel to the axis of the body. Accessory electric organ absent on head or humeral region (Ref. 104297).
 Biology:  This species is collected in shallow areas from 0.5-1.5 m in the dry season or at the beginning of the rainy season. It also occurs in black-water streams along the middle part of the rio Negro Basin (Amazon). Along stream margins, it occurs in well oxygnated waler and prefers weak current with abundant submerged vegetation, roots and leaf litter. In areas with stronger current, this species tends to inhabit submerged trees and tangled roots of epiphytic plants. Variation of physico-chemical water parameters taken in 2002-2007: conductivity 9.0-22.2 µS/cm, temperature 25-26°C, ph 4.01-5.0 and dissolved oxygen 4.12-7.10 mg/L. Stomach contents of one specimen contains parts of zooplankton. Associated genera of gymnotiforms species collected in the area were Brachypopomus and Hypopgus (Ref. 104297).
 IUCN Red List Status: Not Evaluated  (Ref. 96402)
 Threat to humans:  harmless
 Country info:   

 Entered by: Capuli, Estelita Emily - 05.02.16

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