| Family: |
Sternopygidae (Glass knifefishes) |
| Max. size: |
24.1 cm TL (male/unsexed); 17.5 cm TL (female) |
| Environment: |
benthopelagic; freshwater; depth range 10 - 18 m |
| Distribution: |
South America: Brazil. |
| Diagnosis: |
Diagnosis: Distinguished from it congeners (except R nigrimans) by the presence of long pectoral fins (P1/HL = 124.0 ± 9.7 vs. 60-100), with chromatophores generally restricted to the distal portions of the fin rays, creating a dark tip. Differs from R nigrimans by smaller adult body size; shorter caudal appendage with absence of sexual length dimorphism; smaller teeth on premaxilla, mesopterygoid, and dentary; and less numerous teeth on the premaxilla (18-20 vs. 20-25), mesopterygoid (8 vs. 11-13), and dentary (1213 vs. 25-34; n = 2 adults for each species) (Ref. 55969). |
| Biology: |
This species is common in the main channel of the whitewater rivers of the Tefé region where it was found both in trawl-net samples at depths of 10-18 m and also, very abundantly, on sandy and muddy beaches sampled with seine nets. It occurs with R. eastwardi, caviceps, and electrogrammus, but not with nigrimans or navalha. The preferred habitat of this species is turbid river water with electrical conductivity in the range of 80-150 µScm-1. Mature males and females were found during the rising water phase of the Amazon River and were encountered among many other immature specimens on beaches. There in no information about the breeding habits of this species. Feeds on aquatic invertebrates-mainly larvae of Trichoptera and Ephemeroptera larvae, also of Coleoptera and Chironomidae. Some specimens had also ingested large amounts of adult Conchostraca (Ref. 55969). |
| IUCN Red List Status: |
Least Concern (LC); Date assessed: 03 December 2020 Ref. (130435)
|
| Threat to humans: |
harmless |
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