Lamontichthys RIBEIRO, 1939

 Key to the species

 Key to the species of the genus Lamontichthys orientated on CARVALHO PAIXÃO & TOLEDO-PIZA, 2009.

Teeth with short cusps; anterior tip of snout covered with plates or with an inconspicuous area lacking plates; dentary 11.5-19.1% HL in specimens larger than 100 mm SL

> 2 <

Teeth with long cusps; anterior tip of snout not covered with plates; dentary 18.4-23.4% HL in specimens larger than 100 mm SL

> 4 <

19-21 lateral plates in the mid-ventral series; a single large triangular plate extending from base of last pelvic-fin ray to anterior margin of anus; 5-6 lateroventral thoracic

plates in specimens larger than 100 mm SL; dorsal-fin spine not prolonged into a long filament. (lago Maracaibo drainage)

L. maraceibero

15-18 lateral plates in the mid-ventral series; more than one plate from base of last pelvic-fin ray to anterior margin of anus; 6-10 lateroventral thoracic plates in

specimens larger than 100 mm SL; dorsal-fin spine prolonged into a long filament

> 3 <

Pectoral-fin spine prolonged into a long filament in specimens larger than 60 mm SL; head width 97.4-111.1% HL; interorbital distance equal to distance from orbit to exposed margin of cleithrum (rarely shorter). (upper and middle rio Amazonas basin)

L. filamentosus

Pectoral-fin spine not prolonged into a long filament; head width 82.6-96.9% HL; interorbital distance larger than (rarely equal to) distance from orbit to exposed margin of

cleithrum. (rio Orinoco basin)

L. llanero

Distal tip of last dorsal-fin ray extending short of vertical through anal-fin origin; orbital diameter 16.6-17.3% HL in specimens larger than 70 mm SL; two small plates on the

ventral mid-line of the caudal peduncle. (rio Tocantins basin)

L. parakana

> 5 <

L. stibaros

First branched dorsal-fin ray 21.9-26.0% SL and pectoralfin spine 19.7-22.4% SL in specimens larger than 50 mm SL; dark pigments arranged in transversal bands along dorsalfin spine. (upper rio Tocantins basin)

L. avacaneiro

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