| Rhamphichthyidae (Sand knifefishes) |
| 18 cm SL (male/unsexed) |
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benthopelagic; freshwater |
| South America: Paraguay. Gymnorhamphichthys britskii is known from tributaries of the Rio de La Plata system. It is known from the upper and lower Paraguay (Neris et al., 2010) basins in Paraguay and Brazil, and the lower Parana´ basin in Paraguay, Brazil, and Argentina (no records from Uruguay basin). The presence of this species in the Upper Parana was likely caused by the formation of the Itaipu reservoir, which allowed dispersal into upstream portions of the Parana through the former Sete Quedas waterfalls (Ref. 87956) |
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This species is distinguished from its congeners except G. hypostomus in having 5-16 (usually 9-13) large dark saddle-shaped pigment bars over the dorsal midline, extending between the nape and a vertical with the end of the anal fin, and sometimes reaching to or slightly below the lateral line; differs from G. hypostomus in having 141-172 (vs. 178-211) anal-fin rays; a shorter snout, preorbital distance 48.1-60.3% of head length (mean 54.6%) (vs. 58.3-68.6%, mean 63.9%); a larger eye, with diameter 5.7-9.0% of head length (mean 7.0%) (vs. 3.3-5.9%, mean 4.3%); a longer distance from tip of snout to posterior nares, 17.1-22.0% of head length (mean19.2%) (vs. 11.2-17.1%, mean 13.8%); 7 (vs. 9-13) displaced hemal spines; and 64-69 (vs. 71-75) vertebrae to end of anal fin (Ref. 87956). |
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Least Concern (LC); Date assessed: 18 November 2020 Ref. (130435)
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| harmless |
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