| 1a | - Caudal fin with i-12-i or i-11-i rays; teeth pedunculated, bicuspid, numerous (more than 10 per premaxillae), organized in comb and weakly differentiated; sometimes with filamentous extensions on pectoral, dorsal, upper and/or lower caudal spines
| 2 → |
| 1b | - Caudal fin with i-10-i rays; teeth straight, bicuspid, spoon-shaped, not numerous (less than 20 per premaxillae), strongly differentiated, sometimes reduces in size or absent; often with more or less strong whip on upper caudal spine
| 12 → |
| 2a | - Mouth shape elliptical
| 3 → |
| 2b | - Mouth shape horseshoe like; with three buccal papillae, lateral ones triobate; teeth small and not numerous (around 10 per premaxillae)
| Metaloricaria |
| 3a | - Caudal peduncle strongly depressed, elliptical in transverse section (in average, the minimal depth of the caudal preduncle represents 1 to 3 percent of the SL
| 4 → |
| 3b | - Caudal peduncle weakly depressed, more or less circular in transverse section (in average, the minimal depth of the caudal peduncle represents 5 percent of the SL); abdomen naked; body covered by numerous, short and dense odontodes giving a velvet aspect; species of small size (around 50mm)
| Harttiella |
| 4a | - Rostrum present
| 5 → |
| 4b | - Rostrum absent
| 7 → |
| 5a | - Dorsal fin originating more or less in front of the anal-fin origin
| 6 → |
| 5b | - Dorsal fin originating more or less in front of the pelvic-fin origin; abdominal cover complete and weakly structured in two to three rows
| Sturisoma |
| 6a | - Teeth not numerous (around 20 per premaxillae); two to three rows of abdominal plates; gernal aspect slender, reminiscent of a stick
| Farlowella |
| 6b | - Teeth numerous (around 100 per premaxillae); three rows of abdominal plates
| Aposturisoma |
| 7a | - Snout rounded
| 8 → |
| 7b | - Snout pointed; abdominal cover complete without particular organization, or weakly structured in two or three rows
| Sturisomatichthys |
| 8a | - Pectoral fins with i-6 rays
| 9 → |
| 8b | - Pectoral fins with i-7 rays; pectoral spine sometimes with filamentous extensions
| Lamontichthys |
| 9a | - Eye diameter large (on average around 20 percent of head length); tip of snout naked; without filamentous extensions on pectoral, upper and lower caudal spine
| 10 → |
| 9b | - Eye diameter small (on average around 10 percent of head length); tip of snout covered by plates; with filamentous extensions on pectoral, upper and lower caudal spine
| Pterosturisoma |
| 10a | - Scattered long and thin Odontodes at the sides of mature male specimens
| Quiritixys |
| 10b | - No odontodes at the sides of mature male specimen
| 11 → |
| 11a | - Abdomen completely covered with plates; deeply forked caudal fin
| Cteniloricaria |
| 11b | - Abdomen naked or partially covered with plates; caudal fin less forked
| Harttia |
| 12a | - One to three premaxillary teeth that are strongly reduced in size in comparision to dentary teeth
| Fonchiiloricaria |
| 12b | - Premaxillary teeth absent or nearly equal in size in comparison to dentary teeth
| 13 → |
| 13a | - Lower lip bilobate with a median furrow; surface of this lip more or less smooth or weakly papillose; presence of a double adbominal keel; throat never covered; whip on upper caudal spine weak or absent
| 14 → |
| 13b | - Absence of such a combination of characters; lower lip more often strongly papillose or filamentous
| 18 → |
| 14a | - Presence of a secondary structure in the organization of the abdominal cover forming a perfect elliptical area at the level of the pectoral girdle
| Loricariichthys |
| 14b | - Without such structure
| 15 → |
| 15a | - With conspicuous lines of odontodes on head and snout
| 16 → |
| 15b | - Without lines of odontodes on head and snout
| 17 → |
| 16a | - Rostrum strongly pronounced; maxillary barbels short; premaxillary teeth absent; abdomen covered by large rectangular plates organized in three rows
| Hemiodontichthys |
| 16b | - Rostrum weakly pronounced; maxillary and fringed barbels conspicous and gathered in series at the lip corners; premaxillary teeth present; abdomen covered by large plates organized in two rows
| Furcodontichthys |
| 17a | - Abdomen covered by small plates without particular organization; in adults pelvic-fin spine longer than last pelvic-fin ray; in juvenils presence of a conspicuous basicaudal spot
| Pseudoloricaria |
| 17b | - Abdomen covered by medium-sized plates weakly structured in two or three rows; in adults last pelvic-fin ray longer than pelvic-fin spine; in juvenils absence of a conspicuous basicaudal spot
| Limatulichthys |
| 18a | - Lips papillose; fringed barbels of lower lip absent or inconsoicuous
| 19 → |
| 18b | - Lips generelly filamentous or smooth; fringed barbels of lower lip generelly conspicuous
| 25 → |
| 19a | - Abdomen partially to completely covered by plates
| 20 → |
| 19b | - Abdomen naked; snout rounded; mouth circular; postorbital notches deep; stringly depressed body covered by numerous, short and dense odontodes giving a velvet aspect; species of small size (around 90mm)
| Ixinandria |
| 20a | - Abdomen partially to completely covered by medium-sized plates; mouth not circular; postorbital notches deep
| 21 → |
| 20b | - Abdomen covered by very small plates not contiguous; mouth circular and thick; postorbital notches weak; teeth few (around 4 per premaxillae); body depth strong (around 12 percent of SL); presence of a long whip on upper caudal spine; predorsal keels strong
| Spatuloricaria |
| 21a | - Without a secondary structure in abdominal cover; abdominal cover weakly organzied in rows; predosal keels more or less pronounced; species of medium size (generally less than 20cm)
| Rineloricaria |
| 21b | - With a seondary structure on abdominal cover consisting in double median row of plates organized in chevrons; predorsal keels strong; species of large size (generally more than 25cm)
| Dasyloricaria |
| 22a | - Predosal odontodes of mature males present; abdomen completely covered with plates; presence of a whip on upper caudal spine; body thin
| 23 → |
| 22b | - Predosal odontodes of mature males absent; abdomen often not completely covered; whip on upper caudal spine weak or absent; body strong
| 24 → |
| 23a | - Predorsal thin, short, bent, scattered odontodes on mature males present; bundled, long, thin, slightly bent odontodes on headsides present; presence short odontodes on pectoral fins
| Leliella |
| 23b | - Predorsal thin, long, nearly straight odontodes on mature males present; on headsides bundled, long, very thin, slightly bent odontodes and a row of scattered, bent, spiny odontodes which are 3 times thicker and 4 times shorter than the other odontodes in this area present; presence of numerous standing bent, spiny odontodes on pectoral fins
| Hemiloricaria |
| 24a | - Abdomen completely plated; presence of a filamentous extension on upper spine, thickened at origin; westandin area of distribution in northwestern south america
| Fonchiiichthys |
| 24b | - Abdomen more or less completely plated; filamentous extension on upper caudal spine weak or absent; area of distribution in southeastern south america
| Rineloricaria |
| 25a | - Mouth opening without particular shape; the most often predorsal keels strong; body generally weakly depressed
| 26 → |
| 25b | - Mouth opening trapezoidal; predorsal keels weak; body strongly depressed
| 30 → |
| 26a | - Abdominal cover the most often complete made of medium small plates
| 27 → |
| 26b | - Abdominal cover incomplete, made of very small plates not contiguous; equal size of dentary and premaxillary teeth; tooth size-reduced; maxillary barbels long, branched and reaching pectoral-fin origin
| Paraloricaria |
| 27a | - Equal size of dentary and premaxillary teeth; tooth very long
| Brochiloricaria |
| 27b | - Different size of dentary and premaxillary teeth, the latter almost two times longer than the former
| 28 → |
| 28a | - 10 to 15 premaxillary teeth; lips extremely filamentous; maxillary barbels long, strongly branched, and reaching prectoral-fin origin
| Ricola |
| 28b | - 3 to 5 premaxillary teeth; lips filamentous; marxillary barbels not reaching pectoral-fin origin
| 29 → |
| 29a | - Abdominal cover complete; small and nearly triangular transverse section at pectoral-fins
| Loricaria |
| 29b | - Abdominal cover incomplete; body depressed and wide transverse section at pectoral-fins
| Proloricaria |
| 30a | - Rostrum weakly pronounced or absent
| 31 → |
| 30b | - Rostrum strongly pronounced; premaxillary teeth absent; dentary teeth numerous (around 15 per dentary) and reduced in size; lips smooth; maxillary barbels short; abdominal cover complete, made of little plates without particular organization; throat covered
| Reganella |
| 31a | - Abdominal cover complete
| 32 → |
| 31b | - Abdominal cover incomplete, most often consisting in a double median row of plates
| 34 → |
| 32a | - Maxillary barbels inconspicuous, not reaching gill opening; teeth very difficult to observe, invisible in normally preserved specimens
| 33 → |
| 32b | - Maxillary barbels conspicuous, reaching gill opening; teeth visible; head large; body strongly depressed
| Pseudohemiodon |
| 33a | - Head triangular and little; body large; trapezoidal in transverse section with a fleshy flap partially covering the branchiostegal membrane
| Pyxiloricaria |
| 33b | - Head rounded; upper lip with numerous filaments reaching the lower lip margin; with plates on the external margin of the maxillary barbels
| Dentectus |
| 34a | - Premaxillary teeth present
| 35 → |
| 34b | - Premaxillary teeth absent; head rounded; eyes small; maxillary barbels conspicuous, reaching beyond pectoral-fin origin
| Planiloricaria |
| 35a | - Maxillary barbels conspicuous, reaching beyond pectoral-fin origin; lips strongly filamentous
| 36 → |
| 35b | - Maxillary barbels reaching gill opening; lips fairly filamentous
| Crossoloricaria |
| 36a | - Rostrum pointed; 12 fringed barbels; iris operculum generally present
| Rhadinoloricaria |
| 36b | - Rostrum generally rounded; 14 fringed barbels; iris operculum absent or vestigial
| Apistoloricaria |
