| Family: |
Hypopomidae (Bluntnose knifefishes) |
| Max. size: |
16 cm TL (male/unsexed); 13.3 cm TL (female) |
| Environment: |
benthopelagic; freshwater; pH range: 7.5 - 7.6 |
| Distribution: |
South America: upper Madeira River basin in Bolivia, Brazil, and Peru. |
| Diagnosis: |
Anal soft rays: 175-212. Brachyhypopomus arrayae can be distinguished from other species of the genus Brachyhypopomus by the following combination of characters: presence of prominent pale uninterrupted middorsal stripe from occipital region to base of caudal filament (vs. absence in all congeners except B. beebei, B. belindae, B. flavipomus, B. gauderio, B. pinnicaudatus, and B. verdii); anal-fin with 174-212 rays (vs. 214-230 in B. beebei; precaudal vertebrae 20-23 (vs. 24-26 in B. belindae and B. verdii); pectoral fin with 16-19 rays, mode 16 (vs. 12-15, mode 13 for B. gauderio (except populations from Uruguay drainages) and vs. 13-15, mode 14 for B. pinnicaudatus (except populations from coastal French Guiana). It has similar pigmentation and overlapping meristic counts and morphometric proportions with some populations of B. gauderio and B. pinnicaudatus from which it can be distinguished by the contact of a small ascending process on the endopterygoid (mesopterygoid of Mago-Leccia, 1978) with the orbitosphenoid (Arratia & Schultze, 1991; de Santana & Crampton, 2011), (vs. the lack of a contact between the ascending process on the endopterygoid and the orbitosphenoid in B. gauderio and B. pinnicaudatus (Ref. 116763). |
| Biology: |
The type series was sampled from high-conductivity whitewater floodplain sites and from the lower, seasonally inundated reaches of terra firme streams. Found most commonly in marginal root
mats, and in emergent or submerged aquatic vegetation. The recorded water parameters at the sampling sites were the following: conductivity 150-160 μScm-1, dissolved oxygen 5.0-6.0 mgl-1, temperature 27-28°C, and pH 7.5-7.6. Adults in spawning condition were observed during the dry season in June-July 2007. Aquatic insect larvae and other small aquatic invertebrates were found in the stomach contents of specimens from the type locality. Brachyhypopomus arrayae co-occurs in geographical sympatry and ecological syntopy with whitewater floodplain-occurring species such as B. bombilla, B. brevirostris, B. pinnicaudatus, and B. walteri. Largely allotopic in the region of the type locality with the following terra firme stream occurring species: B. alberti and B. sullivani, although B. arrayae was found with B. alberti at the ecotone between terra firme streams and floodplain systems (Ref. 116763). |
| IUCN Red List Status: |
Not Evaluated (N.E.) Ref. (130435)
|
| Threat to humans: |
harmless |
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