Sternarchella calhamazon Lundberg, Coz Fernandes, Campos da Paz & Sullivan, 2013

Family:  Apteronotidae (Ghost knifefishes), subfamily: Apteronotinae
Max. size:  18.54 cm TL (male/unsexed)
Environment:  benthopelagic; freshwater
Distribution:  South America: Brazilian and Peruvian Amazon. Widespread and common in large river channels of the Amazon-Solimões mainstem and major tributaries from the Pará and Tocantins to Iquitos, and upstream in rio Negro to at least the confluence of rio Branco, and in the rio Madeira to at least the confluence wit río Beni.
Diagnosis:  Anal soft rays: 147-165; Vertebrae: 77-79. This species is distinguished from its congeners by the following characters: presence of a flat posterior dorsal surface of the basihyal (vs. ridge); with 12 or fewer teeth on pharyngobranchial (vs. 14); a small body cavity usually with less than 14 pre-caudal vertebrae present (vs. 14); without a crown of thorny projections present at border of parietals and supraoccipital (vs. present in patriciae, orthos) (shared with duccis, orinoco, rex, raptor, schotti, sima); with a deep caudal peduncle, 27-42% HL (vs. 15-21% HL) (Ref. 126780). Description: unique tail shape and the following associated characters: unusually deep caudal peduncle and electric organ; caudal peduncle depth at end of anal fin contained 12-18 times in LEA (length from snout tip to end of anal-fin base), 0.7-2.5 times in its length, and electric organ depth at end of anal fin about equal to or a little greater than snout length; caudal peduncle abruptly tapering before caudal fin; hemal spines above middle third of anal fin elongate, nearly twice longer than adjacent proximal anal-fin radials; two rows of intermuscular bones visible along ventral and ventrolateral sides of posteriorly deepening electric organ; precaudal vertebrae 13-15 including 4 vertebrae of the Weberian complex (Ref. 93342).
Biology: 
IUCN Red List Status: Least Concern (LC); Date assessed: 21 July 2020 Ref. (130435)
Threat to humans:  harmless
Country info:   
 


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