Chaetostoma formosae, Ballen, 2011

Ballen, Gustavo A., 2011, A New Species Of Chaetostoma Tschudi (Siluriformes: Loricariidae) From Colombia With A Definition Of The C. anale Species Group, Papéis Avulsos de Zoologia 51 (26), pp. 383-398 : 384-394

Chaetostoma formosae sp. nov.

( Figs. 1-3 )

Holotype: ICNMHN 17114 , male, 97.4 mm SL, Colombia: Departamento de Boyacá, San Luis de Gaceno, caño Chuy affluent of río Upía , Boyacá – Casanare border, upper río Meta basin, Orinoco drainage, coll. Y. Lopez-Pinto, 1-Jan-2009.

Paratypes: All from Colombia . CZUT-IC 7280 , 14 , 64.2-92.4 mm SL, Meta, San Carlos de Guaroa, río Orotoy below the Chichimene bridge, at the confluence with the quebrada San Francisco , 03°53’00”N, 73°40’40.7”W, coll. A. Ortega-Lara, 25-Mar-2010 ; ICNMHN 1172 , 29 , 43.7 - 41.9 mm SL, Meta, Acacías, río Acacías affluent of río Metica , 3°58’N, 73°42’W, coll. J. Castro & G. Castaño, 26-Feb-1987 ; ICNMHN 1479 , 26 , 50.0- 90.2 mm SL, Meta, Acacías, Manzanares, quebrada La Candelaria affluent of río Guayuriba , 4°07’N, 73°47’W, coll. P. Cala, 10-Jan-1988 ; ICNMHN 2182 , 1 , 84.0 mm SL, Casanare, Yopal, quebrada Cuyandera affluent of río Cusiana , 5°21’N, 72°26’W, coll. J.I. Mojica, 1-Jan-1992 ; ICNMHN 5593 , 3 , 55.0- 80.9 mm SL, Meta, Restrepo, between Restrepo and Cumaral , río Guatiquía basin, 4°15’N, 73°27’W, coll. J. Arroyabe, 1-Jan-1998 ; ICNMHN 7966 , 10 , 38.9-71.3 mm SL, Meta, San Martín, Hacienda Guaduales , 3°37’N, 73°39’W, coll. unknown, 5-Jun-1975 ; ICNMHN 8018 , 3 , 54.8-79.7 mm SL, Meta, Restrepo, río Caney , 4°17’N, 73°32’W, coll. G. Galvis & G. Briceño, 1-May-1993 ; ICNMHN 8024 , 5 , 57.8-72.3 mm SL, Meta, Restrepo, caño Caibe , 4°12’N, 73°26’W, coll. G. Galvis & G. Briceño, 1-May-1993 ; ICNMHN 16364 , 4 , 72.1-103.1 mm SL, Meta, San Martín, Finca El Caduceo, río Camoa (= caño Camoa ), 3°38’N, 73°38’W, coll. G. Galvis et al., 20-May-2006 ; ICNMHN 17594 , 3 , 58.1-89.2 mm SL, Meta, Parque Nacional Natural La Macarena, río Guejar , 3°21’N, 73°57’W, coll. G. Galvis, 1-Sep-1987 ; MLS 1242 , 3 , 80.4 -93.0 mm SL, Casanare, Villanueva, Finca La Victoria , 4°36’N, 72°55’W, coll. Brother R. Casallas , 12-Dec-2007 .

Non-type specimens: All collections from Colombia. ICNMHN 1150 , 63 , 51.8-80.7 mm SL, Meta, Acacías, Hacienda Cisneros, río Acacías , affluent of río Metica , 03°58’N, 73°44’W, coll. P. Cala, 1-Apr-1985 ; ICNMHN 1156 , 3 , 48.1-69.5 mm SL, Casanare, Yopal, small creek 3 km on the road to Guacavia , 05°17’N, 72°27’W, coll. P. Cala, 25-Nov-1971 ; ICNMHN 11966 , 2 , 47.3-76.7 mm SL, Meta, Acacías, Vereda La Esmeralda , 04°01’N, 73°44’W, coll. J.I. Mojica et al., 22-Apr-2004 ; ICNMHN 1476 , 2 , 53.5-71.1 mm SL, Meta, Villavicencio, Villavicencio-Acacías road, río Ocoa , 04°06’N, 73°32’W, coll. A. Silfvergrip, 6-Jan-1988 ; ICNMHN 1477 , 6 , 35.5-52.4 mm SL, Meta, Villavicencio, caño Quenane at the río Negro , coll. A. Silfvergrip, 13-Jan-1988 ; ICNMHN 2526 , 5 , 57.6-95.9 mm SL, Meta, Parque Nacional Natural La Macarena, La Curia Station of INDERENA, caño La Curia, affluent of río Guejar , 03°19’N, 73°59’W, coll. G. Galvis, 19-Sep-1987 ; ICNMHN 3435 , 2 , 59.2-63.4 mm SL, Meta, Acacías, caño Orotoy, affluent of río Acacías , 03°58’N, 73°47’W, coll. G. Galvis et al., 29-Apr-1989 ; ICNMHN 3455 , 1 , 84.5 mm SL, Meta, Acacías, caño Orotoy, affluent of río Acacías , 03°58’N, 73°47’W, coll. G. Galvis et al., 29-Apr-1989 ; ICNMHN 6761 , 13 , 58.2-64.4 mm SL, Meta, Villavicencio, Estación Apiay, río Ocoa , 04°05’N, 73°34’W, coll. Daphnia Consulting Company, 1-Oct-2001 ; ICNMHN 6762 , 13 , 56.7-72.1 mm SL, Meta, Villavicencio, Estación Apiay, río Ocoa , 04°05’N, 73°34’W, coll. Daphnia Consulting Company, 1-Oct-2001 ; ICNMHN 7357 , 1 , 65.2 mm SL, Meta, Villavicencio, Estación Apiay, río Ocoa , 04°05’N, 73°34’W, coll. Daphnia Consulting Company, date unknown ; ICNMHN 7962 , 5 , 53.7-60.2 mm SL, Meta, Villavicencio, Villavicencio-Puerto López road, caño Quenane , 04°05’N, 73°12’W, coll. P. Cala, 1-Feb-1971 ; ICNMHN 7963 , 13 , 38.3-73.7 mm SL, Meta, San Martín, río Humadea , 03°46’N, 73°31’W, coll. P. Cala, 1-Jun-1976 ; ICNMHN 7977 , 3 , 54.0- 77.9 mm SL, Meta, Cumaral, quebrada Piedras Negras , 04°14’N, 73°19’W, coll. G. Galvis, 1-Oct-1990 ; ICNMHN 7987 , 2 , 81.6-90.2 mm SL, Amazonas, Leticia, Parque Nacional Natural Amacayacu , Quebrada Mata-Mata , affluent of río Amazonas , 03°49’N, 69°58’W, coll. J. Ramirez, 1-Apr-1985 ; ICNMHN 8001 , 1 , 70.4 mm SL, Amazonas, Leticia, Parque Nacional Natural Amacayacu , Quebrada Mata-Mata , affluent of río Amazonas , 03°49’N, 69°58’W, coll. J. Ramirez, 1-Apr-1985 ; ICNMHN 8010 , 4 , 52.5 -59.0 mm SL, Meta, Restrepo, caño Caibe , 04°15’N, 73°29’W, coll. G. Galvis, 1-Jun-1989 ; ICNMHN 8015 , 3 , 44.9-52.4 mm SL, Meta, Cumaral, río Caney , 04°13’N, 73°32’W, coll. G. Galvis & G. Briceño, 1-Oct-1993 ; ICNMHN 8022 , 2 , 72.0- 77.2 mm SL, Meta, Guamal, Caño Orotoy, affluent of río Acacías , coll. G. Galvis et al., 7-Dec-1985 ; ICNMHN 8038 , 3 c&s, 69.0- 96.1 mm SL, Amazonas, Leticia, Parque Nacional Natural Amacayacu , Quebrada Mata-Mata , affluent of río Amazonas , 03°49’N, 69°58’W, coll. J. Ramirez, 1-Apr-1985 ; ICNMHN 11970 , 10 , 54.8-66.3 mm SL, Meta, Acacías, caño Orotoy, affluent of río Acacías , 03°58’N, 73°47’W, coll. J.I. Mojica et al., 21-Apr-2004 ; ICNMHN 11971 , 2 , 46.7-48.5 mm SL, Meta, Guamal, Vereda El Carmen, quebrada Guamal, affluent of río Humadea , 03°53’N, 73°46’W, coll. Proyecto Ornamentales Orinoco, 21-Apr-2004 ; ICNMHN 12775 , 9 , 48.4-75.1 mm SL, Meta, Restrepo, caño Mateguadua affluent of río Upía , 04°14’N, 73°33’W, coll. Proyecto Ornamentales Orinoco, 5-Oct-2004 ; ICNMHN 12776 , 43.4-75.9 mm SL, Meta, Acacías, Vereda La Loma, caño Chichimene affluent of río Acacías , 03°59’N, 73°48’W, coll. Proyecto Ornamentales Orinoco, 2-Oct-2004 ; ICNMHN 12777 , 1 , 63.2 mm SL, Meta, Acacías, Vereda La Loma, caño Chichimene affluent of río Acacías , 03°59’N, 73°48’W, coll. Proyecto Ornamentales Orinoco, 3-Oct-2004 ; ICNMHN 13141 , 2 , 47.8-58.6 mm SL, Meta, Acacías, Estación Corveica, río Acacías , 03°59’N, 73°42’W, coll. Proyecto Ornamentales Orinoco, 18-Apr-2004 ; ICNMHN 13208 , 1 , 55.1 mm SL, Meta, Cubarral, río Ariari , 03°47’N, 73°50’W, coll. G. Galvis, date unknown ; ICNMHN 17595 , 18 , 52.6 -84.0 mm SL, Casanare, río Cusiana basin, exact locality unknown, coll . V. Ortiz , 1-Jul-1997 ; ICNMHN 17596 , 4 , 36.6-66.1 mm SL, Meta, Cumaral, caño Caibe , 04°16’N, 73°32’W, coll. Biology Students (Universidad Nacional de Colombia), 23-Apr-2005 .

Diagnosis: Chaetostoma formosae sp. nov. differs from all the species currently in Chaetostoma with the exception of Chaetostoma anale and Chaetostoma jegui by the presence in mature males of an enlarged second unbranched anal-fin ray bearing two distinct posterior dermal folds, and reaching the base of the caudal fin when fully developed ( Figs. 1B , 3 ). Chaetostoma formosae differs from C. anale in having an angular distal pelvic-fin margin in mature males (vs. W-shaped distal margin in mature C. anale males, Figs. 1C , 4B ), and the leading pelvic-fin ray neither elongate nor filamentous, not reaching beyond the adjacent branched ray in mature males (vs. leading pelvic-fin ray both enlarged and filamentous, longer than the remaining rays in mature males of C. anale ). Chaetostoma formosae differs from C. jegui in having dark spots restricted to the head and the dorsal region surrounding the dorsal-fin base, and with compound pterotic and lateral plates bordered by dark pigment (vs. dark background with light blotches in C. jegui ); and by the shape of the distal margin of the pelvic fin strongly projected and angular in mature males, vs. distal margin straight and with leading-fin ray sometimes surpassing the distal margin of the fin as evident in photographs).

Chaetostoma formosae further differs from Chaetostoma anomalum , C. breve , C. carrioni , C. dorsale , C. loborhynchos , C. machiquense , C. microps , C. nudirostre , C. platyrhynchus , and C. sovichthys by having a parieto-supraoccipital dermal keel (vs. skin on the parieto-supraoccipital unmodified in the form of a dermal keel in the cited species) and by the presence of strongly recurved cheek odontodes (vs. cheek odontodes straight in the same species cited above, Figs. 5 and 6 ). In addition, C. formosae differs from C. platyrhynchus by having an unplated snout (vs. snout plated in C. platyrhynchus ).

Description: Measurements presented in Table 1. Small-sized Chaetostoma , with largest examined specimen 103.1 mm SL (paratype male, ICNMHN 16364). Head and body slightly depressed and wide. Dorsal profile of anterior portion of head in lateral view convex from unplated region of snout to vertical through posterior nares, then moderately convex toward dorsal-fin insertion. Dorsal profile of body straight to slightly convex and slightly concave from dorsal-fin insertion to caudal-fin origin. Ventral profile of head and body straight from snout tip to insertion of ventral leading caudal-fin ray.

Interorbital area ranging from slightly flat to convex. Dorsal surface of snout region convex. Head in dorsal view roundish or oval with irregular margin due to development of integument and underlying fatty tissues. Snout naked, covered by epithelial papillae and ridges apparently being formed by fusion of papillae. Anterior margin of plated portion of snout roughly V- or U-shaped, starting on snout midline and then extending further posteriorly to dorsal margin of exposed portion of opercle forming ventral margin nearly parallel or slightly transverse to ventral head margin. Unplated snout region more extensive in mature males than in females. Parieto-supraoccipital dermal keel present, less evident or even apparently lost in faded specimens due to dehydration or inadequate preservation.

All lateral plate series other than ventral series complete from compound pterotic to caudal peduncle; ventral series incomplete anteriorly and beginning just anterior to pelvic-fin insertion. Abdomen completely naked. First anal-fin pterygiophore not exposed. Median series with 23-25 plates (mode 24), showing individual and intraindividual variation.

Cheek apparatus with five protruding hypertrophied cheek odontodes supported by internal bony ossicles and basally covered with skin. Some individuals with six cheek odontodes. Despite apparent variation in number, inner ossicles present only five sockets as evident in c&s specimens. Hyperthropied cheek odontodes distally and strongly recurved, usually not surpassing posterior margin of exposed opercle when adpressed. Some specimens with supernumerary odontodes on fleshy ridge posterior to hypertrophied cheek odontodes and ventral to exposed opercle. Exposed portion of opercle roughly triangular in shape, weak mesial indentation evident externally where musculus dilatator operculi complex inserts onto opercle. Cheek plates not exposed, but located anterior to margin of opercle as evident in c&s specimens. Fleshy ridge posterior to cheek odontodes present, sometimes reaching ventral margin of exposed opercle dorsally when cheek odontodes adpressed. Frontal, infraorbital, nasal, exposed opercle, compound pterotic, sphenotic, and parieto-supraoccipital bones supporting odontodes. Odontodes present on exposed portion of opercle, those on lateral and posterior margins longer and thicker than those on dorsal surface.

Odontodes flat and sharp on lateral plates but flat and spatulate on area between orbit and naris, mesethmoidal region and dorsal surface of snout. Odontodes flat and spatulate on dorsal surface of dorsal-fin leading ray and spinelet, adipose fin, and dorsal leading ray of caudal fin. Odontodes flat and spatulate on ventral and lateral surfaces of pectoral and pelvic fin, and on anterior surface of anal fin and ventral leading ray of caudal fin. Hypertrophied pectoral-spine odontodes basally surrounded by fleshy collar and frequently with small posterior papilla; fleshy papillae present when odontodes are not fully developed, as well as among developed odontodes on pectoral-fin spine (as described for Dekeyseria by Sabaj et al., 1999). Remaining odontodes developing directly on plates and rays without associated papillary soft tissues. All plates of lateral series with largest odontodes on posterior margin and shorter ones on plate surface.

Posterior tip of dorsal fin reaching or surpassing origin of adipose spine when adpressed. Dorsal-fin leading ray not elongate or extending beyond margin of remainder of fin. Dorsal-fin leading ray stiff basally but flexible distally. Distal margin of dorsal fin slightly convex. Margin of dorsal-fin spinelet moderately acute, covered in smaller individuals, yet visible through skin, bearing odontodes protruding through skin. Dorsal-fin spinelet exposed in mature specimens, regardless of sexual condition. Dorsal-fin lock functional. Dorsal-fin ray formula ii,8. Adipose spine preceded by one unpaired plate, spine absent in one specimen examined. Dorsal procurrent caudalfin rays 5-7 (mode 6) and ventral procurrent rays 3-5 (mode 4) as evident in c&s preparations and alcoholpreserved specimens. Caudal fin oblique with lower portion longer than upper portion; dorsal and ventral unbranched leading rays longer than branched rays. Distal margin straight or slightly emarginate. Caudal fin base covered by acute platelets variable in number. Caudal-fin ray formula i,14,i. Anal-fin base short; anal fin length variable and dependent on sexual condition; males with longer rays than females. Relative length of anal-fin rays generally ascending from posteriormost to anteriormost ray fin (i <4 <3 <2 <1 ≤ ii). First branched ray in females usually largest as opposed to modal formula depicted above; variation present in relative length of anal-fin rays in some specimens showing first unbranched ray longer than fourth branched ray. Anal-fin ray formula ii,3-4 (mode ii,4). Pectoral-fin spine with short and thick hypertrophied odontodes on tip but with distinct dorsal row of odontodes throughout midline, showing sexual variation in odontode curvature. Tip of pectoral-fin spine when adpressed reaching to level of vent in mature specimens. Posterior margin of pectoral fin from straight to slightly convex. Tip of adpressed pectoral-fin spine reaching from one-third to middle of leading pelvic-fin ray length. Pectoral-fin ray formula i,6. Tip of pelvic-fin leading ray reaching posteriorly to, or beyond, anal-fin insertion when adpressed. Odontodes on dorsal surface of pelvic-fin rays presenting sexual dimorphism. Pelvic fin with variable distal margin from convex and round in females to strongly convex and angular in mature males (See below for comments on ontogenetic, sexual and individual variation). Pelvic-fin leading ray more than twice as thick as remaining rays. Pelvic-fin ray formula i,5.

Iris operculum present. Short, fleshy flap with round margin present between anterior and posterior nares, deeper mesially. Upper lip with multiple series of papillae, those proximate to mouth opening small and round, followed distally by larger and widely elongate ones. Lower lip with medium-sized round papillae anteriorly and smaller ones posteriorly, with smooth skin close to posterior margin of lip; border crenate. Maxillary barbels moderate in length, separate distally from lower lip. Lower lip basally fused up to one-third or even half of total barbel length in some individuals; fleshy ridge present dorsally almost over entire length of each barbel, also showing individual variation. Buccal papilla present at symphysis of premaxillae. Premaxillary ornamentation usually consisting of individual small papillae arranged transversely. Dentary ornamentation consisting of mesial transverse papillary ridge and secondary single papillae arranged lateral to main ridge.

Jaws wide transversely. Posterior margin of premaxillae forming nearly straight line. Dentary wider than premaxilla. Both ramii with nearly straight cups only recurved on lateral margins. Tooth peduncle fairly long, narrow, and distally recurved. Cusps asymmetrically developed with lateral tooth cusp approximately one-half length of medial cusp. Dentary teeth 50-120, premaxillary teeth 35-79, showing ontogenetic variation increasing with age.

Coloration in alcohol: Overall body background from grayish-green to light brown with black marks on head, fins and body. Head and dorsum with black spots, more numerous on head than on dorsum; lateral plates bordered with black pigment always on anterior portion of body, and occasionally on posterior plates. Posterior head margin bordered by black pigment. Parieto-supraoccipital fleshy keel usually black, but sometimes less intensely pigmented. Pectoral, pelvic, dorsal, anal, and caudal fins with hyaline membranes and black longitudinal bands adjacent to each ray; branched rays unpigmented. Pectoral-fin spine with black longitudinal dorsal band along entire length. Dorsal fin with basal anterior black spot between leading ray and first branched ray. Anteriormost ray in anal fin sometimes pigmented longitudinally; longest unbranched ray and paired posterior ridges in mature males dark gray in coloration. Caudal fin with light reddish areas at least on upper and lower tips, sometimes along entire distal margin. Venter light without dark pigment, postanal ventral plates with some black transverse bars or spots in some individuals.

Etymology: This species is named formosae , an adjective in genitive case derived from the latin formosa. The name honours my sister, Laura María Ballen, in recognition of her unconditional love and support to me.

Sexual variation: Males of Chaetostoma formosae differ in several ways from females. The most conspicuous feature is the enlarged anal fin in mature males, where the second unbranched anal-fin ray elongates, also developing two posterior and longitudinal fleshy ridges and reaching the ventral caudal-fin base once the ray is totally developed ( Fig. 3 ); in females such condition is absent, presenting the second unbranched anal-fin ray comparable in length to the branched adjacent ones. Mature males develop a fleshy dorsal ridge on the pelvic-fin leading ray, from insertion of fin to near the tip of ray; in contrast, females lack such a condition as well as the coloration associated to the fleshy ridge. In addition, mature males show a more extensive unplated portion of snout, whereas mature females show a more plated snout. Development of odontodes on pectoral-fin spines is more pronounced in males than in females but both sexes show odontode development; in addition, the dorsal longitudinal single row presents acute recurved odontodes in mature males whereas mature females show straight odontodes. Distal margin of pelvic fin convex in both sexes, but males always show an angular margin whereas females usually show round margin; however, some larger females can approach the male condition. Males develop several rows of acute recurved hypertrophied odontodes protruding from skin on the dorsal surface of pelvic-fin rays, whereas mature females present odontodes visible through skin but not protruding as in males. Males present a pointed and discrete genital papilla, in contrast to females where the papilla is wide and pad-like. Both kinds of papilla show terminal aperture; however, once reaching maturity and when eggs are mature, females show a swollen posterior portion, what makes the papilla to give the impression of being directed proximal to the vent tube. Males are larger than females (largest male examined 103.1 mm SL vs. largest female examined 71.4 mm SL, both mature adults).

Ontogenetic variation: Some structures show ontogenetic variation. Pectoral-fin spines are longer in mature individuals. In addition, the parieto-supraoccipital fleshy ridge is always evident in immature individuals whereas in some large adults it might be less evident and hard to visualize either by preservation effects or due to a more extensive development of skin surrounding lateral plates occurring with age, therefore causing the ridge to be less evident. Teeth in premaxillary and dentary rami less numerous in immature individuals than in adult ones, probably due to growth of ramus cup with age allowing more teeth to develop, as reported for Farlowella (Retzer & Page, 1996) . Distal margin of pelvic fin also shows ontogenetic variation with immature individuals showing a straight margin in contrast to adult males and females where margin is convex and either angular or round respectively as described above.

Distribution: Chaetostoma formosae is currently known from western piedmont tributaries of the upper río Meta and Guaviare basins, in departments of Meta and Casanare, Eastern Colombia, Orinoco drainage ( Fig. 2 ).

Some referred specimens were reported as collected in Colombian Amazonia ( Fig. 2 , southernmost record with a question mark). Such records are far outside the known range for the genus in Colombia and raise questions on the validity of their locality information. Further searches in the ICNMHN catalog database recovered some other Andean components supposedly collected in the Parque Nacional Natural Amacayacu by J. Ramírez. Those fishes include Astroblepus sp. , Dolichancistrus fuesslii and Eremophilus mutisii , as well as some Amazonian species such as Brachyplatystoma filamentosum . Furthermore, D. fuesslii and E. mutisii are known to have allopatric distributions; the former along the Cordillera Oriental piedmont east of Andes and the latter over the Sabana de Bogotá, without known localities across the eastern watershed of the Cordillera Oriental. Even though some of the collections deposited by J. Ramírez at ICNMHN represent Amazonian taxa, some other specimens belong to strictly Andean species (e.g., Astroblepus spp. , D. fuesslii and E. mutisii ). Additionally, all of the collections by J. Ramírez were catalogued by the same people, increasing the possibility of an erroneous assignation of locality data for fishes apparently originating from several localities on the Cordillera Oriental in Colombia. Given the situation of such collections, those referred specimens (ICNMHN 7987, 8001 and 8038) are assigned to an unknown locality restricting their distribution to the Upper río Meta basin.

The distribution of Chaetostoma formosae is replicated by that of Chaetostoma dorsale (G.A. Ballen, unpubl. data) and Dolichancistrus fuesslii (Ballen & Vari, in prep.). However, both C. dorsale and D. fuesslii reach higher altitudes than do C. formosae , what could be an artifact of sampling effort from collectors working only eventually on the eastern flank of the Cordillera Oriental in Colombia. The same stands valid for C. formosae , for which the currently-known localities are concentrated in highly-sampled areas where most of the inventories were carried out in the last fifty years (e.g., around Villavicencio, Departamento de Meta) but with few records (and specimens) on the northernmost- and southernmost-known localities of this species. This coincidence in distributions might be interesting for deeper questions concerning vicariance biogeography, but to date, the distributions of these three species are not well understood in terms of northern, southern and altitudinal limits. On the other hand, the phylogenetic relationships within both Chaetostoma and Dolichancistrus are not known, therefore precluding any attempt to use such data for a component analysis concerning potential endemism areas east and west of the Cordillera Oriental in Colombia.

Figures

FIGURE 1: Chaetostoma formosae sp. nov., holotype, ICNMHN 17114, adult male, 97.4 mm SL. A) Dorsal view; B) Lateral view; C) Ventral view. Note the enlarged anal fin in B and C. Scale bar equals 10 mm.

FIGURE 2: Distribution of Chaetostoma formosae sp. nov. Square = type locality; Circles = remaining localities. One symbol may represent either more than one locality or lot of specimens. Dashed areas represent the 3000 masl contour, dotted areas represent the 1000 masl contour. Southernmost symbol with a question mark represents an erroneous record for Leticia, Amazonas, Colombia. Base map provided by John D. Lynch.

FIGURE 3: Posterior portion of the body in dorsal view of Chaetostoma formosae sp. nov., holotype, ICNMHN 17114, adult male, 97.4 mm SL. The square detail shows the distal portion of the anal fin in posterior view; small arrows indicate the posterior dermal folds reaching the tip of the enlarged anal-fin ray in mature males.The large arrow indicates the distal portion of the anal fin for which the detail is provided. Scale bar in the square detail equals 3.3 mm.

FIGURE 4: Chaetostoma anale, ICNMHN 17634, adult male, 188.0 mm SL. A) Dorsal view; B) Ventral view. Note the enlarged anal fin and the W-shaped distal margin of the pelvic fins in B. Scale bar equals 20 mm.

FIGURE 5: Supraoccipital region in species of Chaetostoma in dorsal view, anterior portion of body upward; arrows indicate the parietosupraoccipital keel when present. A-B, species showing fleshy supraoccipital ridge; C-D, species with skin on supraoccipital region unmodified. A) Chaetostoma milesi, ICNMHN 16923, subadult male, 122.6 mm SL; B) Chaetostoma formosae sp. nov., ICNMHN 16364, paratype, adult female, 74.7 mm SL; C) Chaetostoma platyrhynchus, ICNMHN 5492, subadult male, 48.4 mm SL; D) Chaetostoma sovichthys, ICNMHN 16221, adult male, 96.4 mm SL. Scale bars equal 3 mm.

FIGURE 6: Cheek odontodes in species of Chaetostoma in dorsal view, anterior portion of body upward; A and C from right side of the head; B and D from left side of the head. A-B, species showing straight cheek odontondes; C-D, species showing recurved cheek odontodes. A) Chaetostoma sovichthys, ICNMHN 16221, adult male, 96.4 mm SL; B) Chaetostoma platyrhynchus, ICNMHN 5492, subadult male, 48.4 mm SL; C) Chaetostoma formosae sp. nov., holotype, ICNMHN 17114, adult male, 97.4 mm SL; D) Chaetostoma milesi, ICNMHN 16923, subadult male, 122.6 mm SL. Scale bars equal 3 mm.