Neoplecostomus microps, photo by K.S.
Cummings
Neoplecostomus microps, photo by K.S.
Cummings
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| 1a. | Body behind head incompletely plated dorsally and laterally. | 2 |
| 1b. | Body behind head completely plated dorsally and laterally (plates may be absent ventrally). | 3 |
| 2a. | Plates anterior to dorsal fin absent. No hypertrophied odontodes on leading edge of pectoral fin spine in nuptial males (VIEW). | Lithogenes |
| 2b. | Plates anterior to dorsal fin present. Hypertrophied odontodes on leading edge of pectoral fin spine in nuptial males (VIEW). | Hemipsilichthys nudulus |
| 3a. | Ventral surface of the pectoral girdle exposed (i.e. supporting odontodes) mesial to the coracoid strut (VIEW - C&D). | Hypoptopomatinae |
| 3b. | Ventral surface of the pectoral girdle covered in skin or plates mesial to the coracoid strut (coracoid strut may be exposed; plates may cover the pectoral girdle, but the odontodes are supported by the plates and not the girdle - VIEW - A&B). | 4 |
| 4a. | Caudal peduncle dorsoventrally flattened; rectangular in cross-section (VIEW). Adipose fin absent. | Loricariinae |
| 4b. | Caudal peduncle not dorsoventrally flattened; oval, round, or triangular in cross-section (if caudal peduncle is depressed, it is never rectangular). Adipose fin absent or present. | 5 |
| 5a. | Edge of snout naked (VIEW - A). | 6 |
| 5b. | Edge of snout covered with plates (VIEW - B). | 9 |
| 6a. | Cheek plates evertible (VIEW - B). Nuptial male with no hypertrophied odontodes along snout (Fig. 6a-c) and no thick flesh present on posterior process of cleithrum. | 7 |
| 6b. | Cheek plates not evertible (VIEW - A). Nuptial male with hypertrophied odontodes present along snout (Fig. 6d) and thick flesh present on posterior process of cleithrum. (The apparent loss of plates on the snout in these species is actually due to thick flesh covering the plates and occurs only in nuptial males.). | 8 |
| 7a. | No fleshy tentacles on snout (VIEW). | Chaetostoma (part) |
| 7b. | Fleshy tentacles on snout (best developed in males, but females possess some small tentacles at edge of snout; VIEW). | Ancistrus |
| 8a. | Plates on abdomen. Dorsal fin spinelet absent (VIEW - location of dorsal-fin spinelet) | Isbrueckerichthys |
| 8b. | No plates on abdomen. Dorsal fin spinelet present as small, rectangular, platelike structure (VIEW - C&D). | Hemipsilichthys |
| 9a. | Postdorsal ridge of 3+ median, unpaired preadipose plates present (adipose fin may or may not be present (VIEW - C). | 10 |
| 9b. | Postdorsal ridge absent or restricted to usually 1 (occasionally 0 or 2) median, unpaired preadipose plates (VIEW - A&B). | 12 |
| 10a. | Adipose-fin membrane and spine absent (VIEW). | Corymbophanes |
| 10b. | Adipose-fin membrane and spine present present. | 11 |
| 11a. | 8-10 dorsal fin rays. Postdorsal ridge contacting dorsal fin membrane in adults. Anterior median, preadipose plates contacting lateral plates. | Delturus |
| 11b. | 7 dorsal fin rays. Postdorsal ridge not contacting dorsal fin membrane. Anterior median, preadipose plates not contacting lateral plates. | Upsilodus ( = Hemipsilichthys gobio?) |
| 12a. | 8+ branched dorsal fin rays. | 13 |
| 12b. | 7 branched dorsal fin rays. | 22 |
| 13a. | More than 60 teeth per jaw ramus. Nuchal plate covered by plates and dorsal fin spinelet covered by skin, both rarely supporting odontodes. No plates on the abdomen. Usually no strong keels on lateral plates [Chaetostoma(Cordylancistrus) platycephalus develops keels on the plates , but they are not well-developed]. | 14 |
| 13b. | Fewer than 60 teeth per jaw ramus. Nuchal plate and dorsal fin spinelet exposed, supporting odontodes. Usually with plates on abdomen (plates may develop late ontogenetically); if specimen is large (> 50 mm SL) and has no plates on abdomen, lateral plates have strong keels formed by long, stout, sharp odontodes. | 17 |
| 14a. | Anal and adipose fins absent (VIEW). | Leptoancistrus |
| 14b. | Anal and adipose fins present. | 15 |
| 15a. | One or two of the cheek odontodes greatly elongated and thickened, longer than head. | Dolichancistrus |
| 15b. | All cheek odontodes of approximately the same length. | 16 |
| 16a. | Cheek odontodes very short (VIEW - A). | Chaetostoma platyrhynchus |
| 16b | Cheek odontodes longer (VIEW - B). | Cordylancistrus |
| 17a. | Adipose fin absent. | 18 |
| 17b. | Adipose fin present. | 19 |
| 18a. | Lateral plates with well-developed keels. Pterotic-supracleithrum greatly expanded, longer than tall (VIEW - C). | Acanthicus |
| 18b. | Lateral plates without well-developed keels. Pterotic-supracleithrum not greatly expanded, taller than long (VIEW - A&B). | Undescribed Rhinelepini from Río Uruguay |
| 19a. | Usually more than 10 teeth per jaw ramus. | Pterygoplichthys |
| 19b. | Usually ten or fewer teeth per jaw ramus. | 20 |
| 20a. | Lower lip round (VIEW - C&D). Tentacles present above upper lip (VIEW - D). Supraoccipital raised into a crest (VIEW). Only 1-4 teeth per premaxilla that are extremely long. | Leporacanthicus |
| 20b. | Lower lip oval (VIEW - A&B). Frimbriae absent above upper lip (VIEW - A-C). Supraoccipital not raised into a crest. Usually more than 4 teeth per premaxilla; teeth moderately long. | 21 |
| 21a. | 8-9 dorsal-fin rays. Pterotic-supracleithrum not expanded (VIEW - A). Found in the Amazon and Orinoco systems, and in the Guianas. | Pseudacanthicus |
| 21b. | 9-11 dorsal-fin rays. Pterotic-supracleithrum moderately expanded (VIEW - B). Found in the Paraná and São Francisco systems. | Megalancistrus |
| 22a. | Dorsal fin with membrane of last ray expanded posteriorly, attaching to preadipose plate or the adipose spine (VIEW - B). | 23 |
| 22b. | Dorsal fin with membrane of last ray not expanded posteriorly, not attaching to preadipose plate or the adipose spine (VIEW - A). | 25 |
| 23a. | Gill openings large. Skin at base of dorsal-fin and pectoral-fin spine textured with fleshy, fimbriate folds (at least in nuptial males; VIEW). | Parancistrus |
| 23b. | Gill openings restricted. Skin at base of dorsal fin and pectoral fin without fleshy, fimbriate folds. | 24 |
| 24a. | Premaxillas long, nearly forming straight line at union; more than 26 teeth per jaw ramus. | Baryancistrus |
| 24b. | Premaxillas short, forming acute angle at union; 26 or fewer teeth per jaw ramus. | Spectracanthicus (includes Oligancistrus) |
| 25a. | Teeth large, spoon-shaped with little or no stalk (VIEW - B). | 26 |
| 25b. | Teeth viliform (threadlike) or large with long stalk (VIEW - A&C). | 27 |
| 26a. | Cheek without elongated, evertible odontodes (VIEW - A). | Cochliodon |
| 26b. | Cheek with elongated, evertible odontodes (VIEW - B). | Panaque |
| 27a. | Cheek plates not evertible (not loosely embedded in connective tissue; firmly attached to suspensorium), if hypertrophied odontodes are present on cheek, their supporting plates are fairly immobile (VIEW - A). Cheek plates covering anteroventral corner of the opercle do have slight mobility, but can not be held at right angle to head. | 28 |
| 27b. | Cheek plates evertible (loosely embedded in connective tissue, not firmly attached to suspensorium), usually with hypertrophied odontodes (VIEW - B). Evertible cheek plates and odontodes can be held almost at right angle to head. | 45 |
| 28a. | Adipose fin absent (raised preadipose plate may be present in Rhinelepis). | 29 |
| 28b. | Adipose fin present (an occasional, aberrant specimen may lack an adipose fin). | 33 |
| 29a. | 1 unbranched and 4 branched anal fin rays. Teeth spoon-shaped (VIEW - B; teeth often smaller than in typical members of the Hypostomus cochliodon group). | Cochliodon levis |
| 29b. | 1 unbranched and 5 branched anal fin rays. Teeth narrow (VIEW - A&C). | 30 |
| 30a. | Spinelet of dorsal fin not well developed (visible only as rectangular patch of odontodes - VIEW - C&D). Anus well separated from anal fin spine. Eye bilobed (dorsal flap of iris present - Fig. 27a). | 31 |
| 30b. | Spinelet of dorsal fin well developed (visible as triangular bone with odontodes - VIEW - B). Anus almost in contact with anal fin spine. Eye not bilobed (dorsal flap of iris absent - Fig. 27b). | 32 |
| 31a. | Hypertrophied odontrodes present along snout margin in nuptial males (Fig. 6d). | Hemispsilichthys (part) |
| 31b. | Hypertrophied odontodes absent along snout margin in all individual (Fig. 6a-c). | Pareiorhina |
| 32a. | One medium-sized plate posterior to pterotic-supracleithrum (VIEW - A). Patch of hypertrophied odontodes on cheek in adult. Lateral plates well keeled. Tall ridges on pterotic-supracleithrum. | Pseudorinelepis |
| 32b. | Patch of small plates just posterior to pterotic-supracleithrum (VIEW - B). No patch of hypertrophied odontodes on cheek in adult. Lateral plates not- or weakly-keeled. Short ridges on pterotic-supracleithrum. | 33 |
| 33a. | Plate present between opercle and pterotic-supracleithrum (VIEW - B). Exposed part of sphenotic not in contact with orbit (VIEW - B). Abdomen fully plated in adults. | Rhinelepis |
| 33b. | Plate absent between opercle and pterotic-supracleithrum (as in VIEW - A). Exposed part of sphenotic in contact with orbit (VIEW - A). Abdomen naked, or with a few scattered areas of plates. | Pogonopomoides |
| 34a. | 1 unbranched and 5 branched anal-fin rays. | 35 |
| 34b. | 1 unbranched and 4 or fewer branched anal-fin rays. | 41 |
| 35a. | Abdomen with no small plates. | 36 |
| 35b. | Abdomen with at least some small plates (plates may be deeply embedded such that only the odontodes pierce the skin). | 39 |
| 36a. | Caudal peduncle with 4-5 rows of plates (VIEW - A). | 37 |
| 36b. | Caudal peduncle with at least one column of only 3 rows of plates (VIEW - B). | 38 |
| 37a. | Hypertrophied odontodes on snout absent in all adults (Fig. 6a-c). Hypertrophied odontodes on cheek do not fold into a groove underneath opercle (Fig. 34a). Lateral section of cleithrum not well developed (Fig. 35a). | Hemipsilichthys? (Undescribed species of uncertain taxonomic relationships) |
| 37b. | Hypertrophied odontodes on snout present in all adults (Fig. 6d). Hypertrophied odontodes present on cheek that fold into a groove underneath opercle (Fig. 34b). Lateral section of cleithrum not well developed (Fig. 35b-2). | Pseudancistrus(part) |
| 38a. | Body narrow, cigar-shaped (Fig. 38). Hypertrophied odontodes absent on cheek of nuptial male (Fig. 6a-c). Suprapreopercle absent (Fig. 39a). | Kronichthys |
| 38b. | Body wide (Fig. 2). Hypertrophied odontodes present on cheek of nuptial male (Fig. 6c). Suprapreopercle present (Fig. 39b). | Hemipsilichthys(part) |
| 39b. | Spinelet of dorsal fin well developed (visible as triangular bone with odontodes; VIEW - B). Anus almost in contact with anal fin spine. Eye not bilobed (dorsal flap of iris absent - VIEW - B). Odontodes on the lateral plates in depressions between raised ridges; no odontodes on top of ridges (VIEW - B). 22-26 lateral line plates. 50+ teeth per jaw ramus. | Pogonopoma |
| 39a. | Spinelet of dorsal fin absent or not well developed (visible only as rectangular patch of odontodes; VIEW - C&D). Anus well separated from anal fin spine. Eye bilobed (dorsal flap of iris present; VIEW - A). Odontodes on lateral plates on ridges; ridges not very tall (VIEW - A). 27+ lateral line plates. Fewer than 40 teeth per jaw ramus. | 40 |
| 40a. | Nuptial male with hypertrophied odontodes along snout margin (VIEW - B). 5+ rows of plates on the caudal peduncle (VIEW - A). No dorsal-fin spinelet (VIEW - location of dorsal-fin spinelet). | Isbrueckerichthys |
| 40b. | Nuptial male without hypertrophied odontodes along snout margin (VIEW - A). At least one column of only 3 rows of plates on the caudal peduncle (VIEW - B). Small, rectangular, platelike dorsal-fin spinelet (VIEW - C&D). | Neoplecostomus |
| 41a. | Hypertrophied odontodes present on the snout of nuptial males (VIEW - B). | 42 |
| 41b. | Hypertrophied odontodes absent on the snout of nuptial males (VIEW - A). | 44 |
| 42a. | Frontal not forming dorsal rim of orbit. Hypertrophied odontodes present on the lateral plates and caudal-fin spines of nuptial males. White to tan base color with black spots laterally. Small plates present on entire abdomen in adults. Distributed west of the Andes in Ecuador. | Isorineloricaria spinosissima |
| 42b. | Frontal forming dorsal rim of orbit . Hypertrophied odontodes absent on the lateral plates and caudal-fin spines of nuptial males. Brown or gray base color with mottling laterally. Small plates on abdomen either absent or sparsely distributed. Distributed east of the Andes. | 43 |
| 43a. | Hypertrophied odontodes on snout present in adult males and females. Hypertrophied odontodes present on cheek that fold into a groove underneath opercle. | Pseudancistrus (part) |
| 43b. | Hypertrophied odontodes on snout present only in nuptial males. If hypertrophied odontodes present on cheek they are at a right angle to the head and do not fold into a groove underneath opercle (VIEW). | Hemipsilichthys (part) |
| 44a. | Distributed west of the Andes (including the Lago Maracaibo basin). Dark brown ground color. 2+ (usually 3 although two rows may coalesce) rows of plates between suprapreopercle and exposed portion of opercle (VIEW C). | Hemiancistrus annectens group (an undescribed genus sister to Pterygoplichthys) |
| 44b. | Distributed east and west of the Andes. Dark brown or white to tan ground color (those species to the west of the Andes have a white to tan ground color). 1-2 (usually 1) rows of plates between suprapreopercle and exposed portion of opercle (VIEW A). | 58 |
| 45a. | Median row of odontodes on each lateral plate forming sharp keels. | Dekeyseria |
| 45b. | Median row of odontodes on each lateral plate not forming sharp keels. | 46 |
| 46a. | Fewer than 10 teeth per jaw ramus. Premaxillas short, forming acute angle at union | 47 |
| 46b. | More than 10 teeth per jaw ramus. Premaxillas long, nearly forming straight line at union. | 50 |
| 47a. | Lower lip oval (VIEW - A&B). 5 rows of plates on the caudal peduncle (VIEW - A) | 48 |
| 47b. | Lower lip round (VIEW - C&D). 3 rows of plates on the caudal peduncle (VIEW - B). | 49 |
| 48a. | Dentary teeth very long; crowns consisting of one large and one small lobe, moderately spoon-shaped (VIEW - C). With gold spots in life (VIEW). Large adult size >100 mm. | Scobinancistrus |
| 48b. | Dentary teeth moderately long; crowns consisting of two nearly equally sized lobes, not spoon-shaped. With dramatic black and white stripes and a black E on the snout; VIEW). Small adult size <100 mm. | Hypancistrus |
| 49a. | Lower lip fimbriate (VIEW - C). | Exastilithoxus |
| 49b. | Lower lip not fimbriiate (as in VIEW - D). | Lithoxus |
| 50a. | Cheek with only 3 odontodes; cheek odontodes stout and strongly hooked anteriorly (VIEW). | Hopliancistrus |
| 50b. | Cheek with 4+ odontodes; cheek odontodes not particularly stout and relatively straight to moderately hooked. | 51 |
| 51a. | 4-5 rows of lateral plates on caudal peduncle (VIEW - A). | 52 |
| 51b. | 3 rows of lateral plates on caudal peduncle (VIEW - B). | 56 |
| 52a. | Hypertrophied odontodes along edge of snout from evertible odontodes to tip of snout present (present on both males and females although much shorter in females; VIEW - B). Fleshy tentacules associated with odontodes along snout margin (VIEW). Usually 4 predorsal plates (count includes nuchal plate).. | Pseudancistrus |
| 52b. | No hypertrophied odontodes along edge of snout from evertible odontodes to tip of snout (VIEW - A). No fleshy tentacules associated with odontodes along snout margin. 3 predorsal plates (count includes nuchal plate). | 53 |
| 53a. | Usually only 3 (up to 8) elongated cheek odontodes (present only in adults). 2-3 (usually 3) rows of plates between suprapreopercle and exposed opercle (VIEW - C). Posterior margin of posterior process of cleithrum straight (VIEW - A). Distributed solely west of Andes (including Maracaibo basin, but not the Gulf of Guayaquil drainage or drainages south of the Guayaquil). Stomach usually large. | Hemiancistrus annectens group (an undescribed genus sister to Pterygoplichthys) |
| 53b. | Usually at least 10 elongated cheek odontodes present in juveniles and adults. 1-2 (usually one) rows of plates between suprapreopercle and exposed opercle (VIEW - C). Posterior margin of the posterior process of cleithrum pointed (VIEW - B). Distributed both west (only in the Gulf of Guayaquil drainage and drainges south of the Guayaquil) and east of Andes. Stomach small. | 54 |
| 54a. | Distributed west of the Andes. | New genus (formerly Hemiancistrus landoni) |
| 54b. | Distributed east of the Andes. | 55 |
| 55a. | Opercle not supporting odontodes in adults (opercles of juveniles do possess odontodes). Body generally either with contrasting bars (spots sometimes on head and fins), gray with black spots, or tan with very large black spots). | Peckoltia |
| 55b. | Opercle supporting odontodes at all sizes. Body generally spotted, mottled, or unmarked. | Hemiancistrus |
| 56a. | Whiskerlike odontodes anterior to elongated cheek odontodes (VIEW - B). Tentacules on edge of snout of nuptial male longer than associated odontodes (VIEW - D). | Lasiancistrus |
| 56b. | No whiskerlike odontodes anterior to elongated cheek odontodes (all cheek odontodes thick). If tentacules present along snout in nuptial male, they are not longer than their associated odontodes (VIEW B-C). | 57 |
| 57a. | No extremely elongated, anteriorly oriented odontodes on snout of nuptial male. Hypertrophied odontodes along snout margin present in adult males and females. Pectoral-fin spine reaches anus in adults. | New Genus |
| 57b. | Extremely elongated, anteriorly oriented odontodes on snout of nuptial male (VIEW). Hypertrophied odontodes along snout margin present only in adult males. Pectoral-fin spine does not reach anus in adults. | Neblinichthys |
| 58a. | Numerous small papillae inside buccal cavity behind upper jaw. Nuptial males with hypertrophied odontodes only on posterior half of body. Nuptial males with at least the median teeth unicuspid. | Aphanotorulus |
| 58b. | No numerous small papillae inside buccal cavity behind upper jaw. Nuptial males with hypertrophied odontodes on entire body behind head or with hypertophied odontodes absent on body. All individuals with teeth bicuspid. | Hypostomus |
