Mylossoma albiscopum ( Cope, 1872 )

Mateussi, Nadayca T. B., Oliveira, Claudio & Pavanelli, Carla S., 2018, Taxonomic revision of the Cis-Andean species of Mylossoma Eigenmann & Kennedy, 1903 (Teleostei: Characiformes: Serrasalmidae), Zootaxa 4387 (2), pp. 275-309 : 280-285

Mylossoma albiscopum ( Cope, 1872)

( Figs. 1 , 4–9 ; Table 2)

Myletes albiscopus Cope, 1872: 267 , pl. 12, Fig. 1 [original description; type-locality: "Ambyiacu"].

Myletes duriventris (non Cuvier, 1818). — Valenciennes, in Cuvier & Valenciennes, 1850: 206 [in part; redescription].

Mylossoma albiscopus .— Fowler, 1907: 475 [lectotype designation].— Nelson, 1961: 608 [swim bladder morphology].— Böhlke, 1984: 42 [type-material listed].

Mylosoma [sic] albiscopus .— Eigenmann, 1910: 444 [listed].— Eigenmann, 1915: 266 [partim; brief redescription].

Mylossoma argenteum Ahl, 1928: 192 [original description; type-locality: "Amazonenstrom"].— Ahl, 1929: 273 [redescription].

Mylossoma duriventris .— Norman, 1929: 813 [partim; brief description].— Ortega & Vari, 1986: 9 [listed, Peru].— López & Nass, 1989: 121 [larval development].— Taphorn, 1992: 481 [partim; description].

Mylossoma albiscopum .— Eigenmann & Allen, 1942: 249 [diagnosis].

Mylossoma duriventre (non Cuvier, 1818).— Eigenmann & Allen, 1942: 249 [partim; Peru].— Géry, 1976: 50 [listed].— Machado-Allison & Castillo, 1992: 19 [redescription; synonymy; allometry; Orinoco basin, Venezuela].— Taphorn, 1992: 481 [description; río Apure basin, Venezuela].— Machado-Allison & Fink, 1996: 78 [Río Orinoco basin; brief description].— Oliveira & Araújo-Lima, 1998: 349 [larvae habits and distribution, rio Solimões, Brazil].— Jégu, 2003: 187 [partim; listed].— Cabrera & Vaca, 2006: 21 [Pando, Bolivia].— Santos et al., 2006: 45 [Manaus area, fishery].— Brito et al., 2011: 129 [Orinoco basin; brief description; ecological notes].— Ota et al., 2013: 26 [rio Madeira basin, Brazil; brief description, photo].

Diagnosis: Mylossoma albiscopum differs from M. aureum by presenting the last abdominal spine reaching the anal-fin origin or almost (vs. last abdominal spine clearly separated from anal-fin origin), 36–37 vertebrae (vs. 38– 39), and a conspicuous black blotch on the opercle (vs. blotch absent or faded on the opercle). It differs from M. duriventre and M. unimaculatum by having 31 (rarely 30) to 38 branched anal-fin rays (vs. 26 to 32). Also, it can be distinguished from M. unimaculatum by having 28 to 36 circumpeduncular scales (vs. 34 to 40) and 74 to 99 perforated scales (vs. 95 to 110).

Description: Morphometric data presented in Table 2. Body deep, compressed laterally. Dorsal profile slightly concave at posterior region of head and convex between head and dorsal fin. Ventral profile convex; slightly concave at isthmus and strongly convex from this point to end of anal fin. Highest body depth on vertical line passing through dorsal-fin origin. Caudal peduncle deeper than longer.

Eyes lateral at middle of head; upper margin of eyes below longitudinal axis of lateral-line origin. Frontal and parietal fontanel broadly expanded laterally. Snout short and rounded in lateral view. Nostrils dorsolateraly positioned, above longitudinal axis through upper margin of eye.

Mouth terminal, slightly upturned, at same level of orbits. Premaxilla slightly projected, with inner premaxillary row over or surpassing dentary row ( Fig. 6 ). Premaxillary teeth molariform, with robust base; outer portion of anteriormost three teeth of outer row and posterior portion of remaining teeth pointed. Inner premaxillary row with two teeth, separated from outer row. Outer premaxillary row with five teeth. Dentary with four (rarely five) tricuspid, robust, molarifom teeth; symphyseal dentary teeth present, with robust base and large conical cusp, behind main row. Maxilla edentulous ( Fig. 2 ).

First gill arch with elongated, conical gill rakers; epibranchials 8(1), 10(2), 11(1), 12(30), 13(15), 14(15) or 15(2); one (65) gill raker at cartilage between epi- and ceratobranchial; ceratobranchials 11(3), 12(1), 13(7), 14(21), 15(15), 16(18) or 17(5).

Body completely covered by small cycloid scales. Accessory scales covering intersections of major scales, mainly at anterior portion of body. Lateral line complete, with 74(1), 76(1), 78(1), 79(2), 80(0), 81(1), 82(4), 83(3), 84(6), 85(9), 86(5), 87(6), 88(9), 89(5), 90(7), 91(9), 92(12), 93(6), 94(6), 95(6), 96(3), 97(1), 98(2) or 99(1) perforated scales, slightly advancing on caudal fin. Scales series above lateral line 42(1), 43(3), 44(2), 45(1), 46(9), 47(3), 48(4), 49(4), 50(15), 51(6), 52(9), 53(6), 54(6), 56(3), 57(2) or 58(1). Scales below lateral line 37(1), 40(4), 41(2), 42(3), 43(4), 44(3), 45(6), 46(4), 47(7), 48(3), 49(4), 50(9), 51(3), 52(5), 53(5), 54(3), 55(2) or 56(2). Circumpeduncular scales 28(6), 30(13), 32(38), 33(8), 34(25), 35(1) or 36(4). Ventral keel with a serra of spines. Pre-pelvic spines 23(2), 24(2), 25(6), 26(9), 27(7), 28(25), 29(18), 30(25), 31(17), 32(6), 33(4) or 34(1). Postpelvic spines 10(2), 11(3), 12(18), 13(31), 14(40), 15(19), 16(7) or 17(1). Anal spines 5(17), 6(43), 7(45), 8(18) or 10(2) ( Fig. 6 ).

Dorsal fin not preceded by spine, its origin equidistant from tip of snout and end of hypural plate. First dorsalfin ray much shorter than second ray; in some specimens covered by skin, in such cases discernible only if dissected or x-rayed ( Fig. 6 ). Branched dorsal-fin rays gradually decreasing in size, dorsal-fin rays 13(3), 14(28), 15(57) or 16(19). Adipose fin short, longer than deep, entirely covered by small scales. Pectoral fin falcate, with i(107) + 12(3), 13(2), 14(26), 15(53), 16(34), 17(6) or 18(1) rays. Pelvic fin small, with i + 6 (123) branched rays. Anal fin long, with convex edge, median and posterior rays longer than anterior ones, not lobed; sheath of scales covering at least two-thirds of anal-fin length; anal-fin rays 30(2), 31(6), 32(6), 33(17), 34(35), 35(26), 36(17), 37(14) or 38(5). Caudal fin bifurcated, lobes of similar size, with 16(4), 17(106), 18(5) or 19(1) rays. Vertebrae 36(4) or 37(4). Supraneurals 4(8).

Color in alcohol. General body color brownish-yellow, darker dorsally ( Fig. 5 ). Fins hyaline to yellowish; caudal-fin and anal-fin bases often dark. Conspicuous black or brown blotch on opercle. Juvenile specimens with several vertical brownish bands on flanks and a rounded black or brown ocellar blotch below dorsal fin ( Fig. 7 ).

Color in life. General body color silvery, darker dorsally; orange or reddish tint on anterior portion of abdominal region, head and around the eyes. Presence of a black blotch on opercle. Anal fin with yellow to orange tint, sometimes with a dark band along distal margin; dorsal- and pectoral-fin bases orange, with posterior portion hyaline; pelvic fin hyaline; caudal fin with yellow, orange and red tint, sometimes with dark distal band ( Figs. 1 , 8 , 9 ).

Geographic distribution. Mylossoma albiscopum is widespread across the Amazon and Orinoco river basins ( Fig. 3 ).

Ecological notes. According to Santos et al. (2006), Mylossoma albiscopum is an herbivore with tendency to omnivory feeding on fruits, seeds and larvae of aquatic insects. The species commonly occurs at whitewater rivers and their associated floodplain lakes and channels ( Santos et al., 2006; Machado-Allison, 2005). The spawning period is relatively long, with two spawning peaks during the flood season ( Santos et al., 2006). Mylossoma albiscopum is one of the most important species in commercial fisheries in the Brazilian Amazon (e.g. Cardoso & Freitas, 2008; Ota et al., 2013).

Molecular data. DNA barcoding method showed a high level of genetic distance between Mylossoma albiscopum (called as M. duriventre “group 5” in Mateussi et al., 2016) and the remaining analyzed species, ranging from 0.053 to 0.084. Mylossoma albiscopum was recovered as the sister-taxa to M. duriventre and M. unimaculatum (called as M. duriventre “group 3 and 4” in Mateussi et al., 2016).

Remarks. Myletes albiscopus was described by Cope (1872) from the río Ambyiacu, a tributary of the rio Amazonas at Departamento Loreto, Peru and, recorded from the rio Paraguay basin in Paraguay, by Eigenmann & Kennedy (1903). Eigenmann (1915) redescribed Mylosoma [sic] albiscopus based on specimens from the Paraguay and Amazon rivers basins, i.e., his account mixed specimens of both M. albiscopum and M. duriventre . This confusion between both species persisted in the literature up to the present.

Mylossoma albiscopum has been considered a synonym of M. duriventre ( Taphorn, 1992; Jégu, 2003). Since specimens from both the Amazon and Orinoco river basins differ from the species occurring at the La Plata basin, and the restriction of the type-locality of Myletes duriventris (= Mylossoma duriventre ) for the rio Paraguai basin (see under this species, below), we consider herein M. albiscopum as a valid species restricted to the Amazon and Orinoco basins. Therefore, records of M. duriventre from these basins actually correspond to M. albiscopum .

Material examined. Type-material. Lectotype: ANSP 8021 , 1 (rd), 160 mm TL, río Ambyiacu , Peru, R. Perkins. Lectotype of Myletes albiscopus (designated by Fowler, 1907) . ZMB 20854, 1 (rd), 97.2 mm SL, rio Amazonas. Syntype of Mylossoma argenteum . Non-types. Bolívia. Rio Amazonas basin. Beni: MNHN 1989.1381, 3, 99.2–110.5 mm SL, Trinidad , rio Mamore , 0 1 Sep 1984, L. Lauzanne & G. Loubens. Brazil. Rio Amazonas basin. Amapá: LBP 20517, 1, 113.1 mm SL, Laranjal do Jari , rio Jari , 00°42'57''S 52°29'42''W, 25 Sep 2015, C. Oliveira & B.F. Melo . Amazonas: INPA 20263, 2, 92.3–121.6 mm SL, Manaus, canal Xiborena (trib. rio Amazonas), 03°12'30"S 59°59'00"W, 13 Apr 2000, C. Cox-Fernandes et al. INPA 28058, 2, 29.7–58.5 mm SL, Tefé , RDS Amanã, Lago Teodoro (trib. rio Amanã ), 02°44'17"S 64°39'44"W, 15 Mar 2003, M. Catarino . INPA 29057, 2, 97.2–105.9 mm SL, Carauarí, RDS Uacari, rio Juruá , 05°55'51"S 67°49'16"W, 23 Nov 2007, R. G. Frederico & L. J. Queiroz . INPA 29064, 3, 85.5–117.6 mm SL, Carauarí, RDS Uacari, rio Juruá , 05°55'51"S 67°49'16"W, 24 Nov 2007, R. G. Frederico & L. J. Queiroz . INPA 33884 , 1 , 104.3 mm SL, Nhamundá , rio Amazonas, 02°13'51"S 56°46'23"W, 21 Sep 2009, R. Leitão & H. Lazzarotto . INPA 45467 , 1 (sk), Careiro da Várzea, Ilha Marchantaria, lagos do Catalão , 03°14'00"S 59°56'00"W, 0 2 Feb 2014, S. A. Amadio . Pará: INPA 33899 , 1 , 148.6 mm SL, Oriximiná, lago Caipuru, rio Trombetas tributary, 01°46'34"S 55°56'37"W, 26 Sep 2009, R. Leitão & H. Lazzarotto . MPEG 10118, 2, 44.1–50.8 mm SL, Juruti, lago do Piranha , rio Amazonas, 02°12'40"S 56°06'59"W . MPEG 14102, 2, 82.6–87.4 mm SL, Juruti , rio Amazonas, 02°11'23"S 56°08'04"W . MPEG 15148, 2, 79.3–85.9 mm SL, Juruti , rio Amazonas, 02°12'34.6"S 56°08'10"W . Roraima: INPA 2266, 3, 231.7– 239.7 mm SL, ilha de Maracá, rio Uraricoera, 03°25'00"N 61°40'00"W, 13 Aug 1988, M. Jégu . Rio Madeira basin. Amazonas: INPA 24350 , 4 , 96.0– 124.3 mm SL, comunidade Cachoeirinha, Manicoré , rio Madeira , 05°48'34"S 61°17'48"W (city coordinates), 16 Sep 2004, L. R. Py-Daniel . INPA 24351 , 3 , 118.8 –130.0 mm SL, comunidade Itapinima, rio Madeira , 05°24'37"S 60°43'16"W, 22 Sep 2004 . INPA 24352 , 1 , 121.8 mm SL, comunidade Vencendor, lago Acará , 03°38'09"S 62°42'31"W, 18 Sep 2004, L. R. Py-Daniel et al. . INPA 38478 , 1 , 82.1 mm SL, Humaitá, lago do Pirapitinga , 07°00'45"S 62°51'32"W, 19 Aug 2011, Costa et al. . INPA 38611, 2, 71.9–72.6 mm SL, Humaitá, lago Redondo, 06°43'04"S 62°19'34"W, 23 Aug 2011, Costa et al. LIRP 8677 , 1 , 86.4 mm SL, Manicoré, rio Manicoré , 05°52'06"S 61°21'22"W, 0 3 Aug 2010 . UFRO-ICT 20879 , 2 , 78.5 –122.0 mm SL, Nova Olinda do Norte, lago Sampaio , 03°49'06"S 59°05'30"W, 16 Sep 2012, J. A. Lima-Filho . Rondônia: INPA 21908 , 1 , 131.9 mm SL, Vale do Guapo, rio Cautário, 12°03'21"S 64°22'33"W, 12 Jul de 2003, G. Torrente-Vilara. LBP 10144, 1 (rd), 242.6 mm SL, Porto Velho, rio Abunã , 09°01'06"S 65°43'00"W, 23 Aug 2010, C. Oliveira et al. . LBP 12089, 1, 38.4 mm SL, Porto Velho, rio Madeira , 08°51'42"S 64°03'49"W, 26 Aug 2010, C. Oliveira et al. . MZUSP 13963 , 2 (rd), 152.3–154.7 mm SL, lago Cururu, rio Machado, 08°20'48"S 62°42'24"W, 20 May 1978, M. Goulding. NUP 17118, 1, 165.1 mm SL, Alta Floresta d'Oeste, rio Branco (trib. rio Guaporé ), 11°55'37''S 62°24'32''W, 13 Sep 2013, H. Pains-Silva . UFRO-ICT 13307 , 2 , 108.8 –132.0 mm SL, Porto Velho, cachoeira Santo Antônio, rio Madeira , 08°48'30"S 63°36'53"W, 13 Dec 2008 . UFRO-ICT 8138, 2, 149.3– 162.5 mm SL, Costa Marques, Colocação Jatobá, rio Cautário , 12°35'S 60°55"W, 29 Aug 2003, G. Torrente-Vilara . UFRO-ICT 20211 , 1 , 141.1 mm SL, Guajará-Mirim, rio Pacás Novos , 10°51'47''S 65°16'21''W, 20 Jan 2013, F. Vieira . UFRO-ICT 20223 , 1 , 84.1 mm SL, Guajará-Mirim, rio Guaporé , 11°36'36''S 65°13'30''W, 10 Jan 2013, F. Vieira . Rio Negro basin. Amazonas: INPA 3683 , 1 , 194.5 mm SL, cachoeira do Caranguejo, rio Negro , 01°45'59"S 62°41'47"W, 0 7 Mar 1990 . LBP 21790, 1, 125.6 mm SL, Manaus, Catalão, rio Negro, 03°12'00''S 59°57'39''W, 12 May 2016, N.T.B. Mateussi et al. LBP 21833, 3, 102.5– 140.9 mm SL, Manaus, Catalão, rio Negro , 03°12'00''S 59°57'39''W, 12 May 2016, N.T.B. Mateussi et al . Rio Purus basin. Acre: MCP 35491, 1 , 109.7 mm SL, Rio Branco, rio do Rola (trib. rio Acre ), 10°03'24"S 68°10'29"W, 24 Jun 2003 . Amazonas: INPA 28222 , 1 , 230.5 mm SL, Pauiní, rio Moaco, rio Purus , 07°52'55"S 69°11'18"W, 21 Mar 2007, L. H. Claro & R. G. Frederico . INPA 28227 , 1 , 169.2 mm SL, Pauiní, rio Moaco, rio Purus , 07°52'55"S 69°11'18"W, 21 Mar 2007, L. H. Claro & R. G. Frederico . INPA 36677, 2, 105.4– 125.8 mm SL, Beruri, RDS Piagaçu-Purus, lago Adão, rio Purus , 04°13'20"S 61°53'53"W, 24 Oct 2009, B. Morales . INPA 36691 , 4 (6), 106.0– 132.7 mm SL, Beruri , RDS Piagaçu-Purus, lago Macacão, 04°13'S 61°53'W, 27 Oct 2009, B. Morales . INPA 41655 , 11 , 75.0–182.0 mm SL, Tapauá, igarapé Castanhalzinho, rio Purus , 04°59'50"S 62°59'38"W, 10 Aug 2012, L. R. Py-Daniel et al. . Rio Solimões basin. Amazonas: INPA 3057 , 1 , 88.8 mm SL, Careiro, lago Jacaretinga , rio Solimões , 03°46'05"S 60°22'09"W, 10 Jul 1989, M. Kirkaparick . INPA 3774 , 3 (7), 124.5–136.0 mm SL, rio Javari , 04°11'02"S 70°35'02"W, 14 Oct 1976, Ictiologia INPA staff . INPA 48706, 2, 38.3–109.1 mm SL, Iranduba, ilha da Marchantaria, rio Solimões , 03°17'05"S 60°11'10"W, 20 Mar 1976, Ictiologia INPA staff . INPA 10145 , 2 , 53.0–56.0 mm SL, Iranduba, ilha da Marchantaria, rio Solimões , 03°17'05"S 60°11'10"W, 17 Feb 1992, P. Petry . INPA 19437 , 1 , 69.4 mm SL, reserva Mamirauá, lago Arawaé , c. 02°11'32"S 65°42'30"W, 0 1 Jul 1996, W. Crampton . INPA 23017 , 2 , 79.0–81.0 mm SL, comunidade Catalão, rio Solimões , 0 3 Nov 1999, L. R. Py-Daniel et al. . INPA 48704, 4, 39.6–50.3 mm SL, Tabatinga, rio Solimões, 03°57'32"S 69°20'19"W, 0 2 Sep 2003, J. Zuanon et al. INPA 48703, 4, 21.5–63.8 mm SL, Coari, Ressaca Geral do rio Solimões , 03°57'32"S 69°20'19"W, 13 Sep 2003, L. R. Py-Daniel et al. INPA 33146 , 1 , 46.4 mm SL, Fonte Boa, lago Ressaca Grande, rio Solimões tributary, 02°28'26"S 66°09'17"W, 0 8 Sep 2003, J. Zuanon et al. INPA 33148 , 1 , 67.7 mm SL, Anamã, rio Solimões , 03°39'29"S 61°29'28"W, 16 Sep 2003, L. R. Py-Daniel et al. . INPA 33150, 3, 37.6–44.6 mm SL, Santo Antônio, rio Solimões, 03°09'13"S 67°58'44"W, 0 5 Sep 2003, J. Zuanon et al. INPA 33382, 5, 53.1–69.6 mm SL, Coari , lago do Apurá , rio Solimões tributary, 03°53'55"S 63°25'37"W, 12 Sep 2003, L. R. Py-Daniel et al. MCP 31654, 1 , 126.0 mm SL, Alvarães, flooded forest between lago Periquito Redondo and lago Periquito Comprido, confluence between rio Solimões and rio Japurá, 03°05'26"S 64°46'31"W, 0 5 May 1998, W. Crampton . MPEG 4774, 3, 66.7–76.4 mm SL, Maraã, rio Solimões, c. 02°18'07"S 65°00'03"W. LBP 1695, 3, 25.1–47.8 mm SL, Careiro , lago do Vanico , rio Solimões , 03°09'17"S 59°53'12"W, 0 5 Jul 2003, C. Oliveira et al. LBP 18175, 3 (rd), 59.8–71.0 mm SL, Manacapuru, rio Solimões , 03°18'53"S 60°38'58"W, 21 Aug 2013, C. Oliveira et al. MCP 31655, 1 , 88.9 mm SL, Tefé, canal do Mamirauá, 03°06'40"S 64°47'52"W . MCP 31656, 1 , 83.4 mm SL, Alvarães, ilha do Prego, rio Solimões , 03°10'37"S 64°48'01"W, 15 Jan 2001 . Rio Tapajós basin. Pará: MCP 20992, 5 , 84.0– 91.9 mm SL, Santarém, rio Tapajós, 02°25'00"S 54°44'00"W. Colombia. Rio Amazonas basin. Amazonas: LBP 24293, 2, 53.7–56.5 mm SL, Leticia, Lago Yahuarcaca, rio Amazonas, 04°11'45''S 69°57'20''W, 12 Nov 2016, C. Oliveira & B.F. Melo . Rio Meta basin. Meta: MNHN 2007.0227, 2, 189.7– 198.9 mm SL, Puerto López , Caño Victoria , rio Meta , 04°15'N 72°30'W, 0 4 May 1995, S. P. Pedreros. Peru. Rio Amazonas basin. Loreto: LBP 12540, 5, 38.8–45.8 mm SL, isla de Iquitos, río Itaya tributary, Punchana, Maynas, 03°43'39"S 73°13'58"W, 16 Aug 2011, C. Oliveira et al. . LBP 24292, 1, 65.9 mm SL, rio Amazonas , 04°14'04''S 69°57'42''W, 14 Nov 2016, C. Oliveira & B.F . Melo. Río Ucayali basin. Ucayali: MCP 44251, 1 , 76.4 mm SL, Pucallpa, Caño Cashibo (trib. río Yarinacocha ), 08°16'15"S 74°37'50"W, 28 Jul 2009 . Venezuela. Rio Orinoco basin. MNHN 1887.0806 , 1 , 56.1 mm SL ; MNHN 1887.0807, 1, 66.2 mm SL; MNHN 1887.0808, 1, 45.5 mm SL; MNHN 1887.0809 , 1 , 44.3 mm SL, rio Orinoco, 1887, Chaffanjon. Bolivar: LBP 18873, 2, 112.4– 116.6 mm SL, Caicara del Orinoco , Laguna de Castilleros , 07°30'50"N 66°09'19"W, Apr 2014, A. Granado . Guárico: LBP 10230, 1, 135.2 mm SL, Cabruta, río Apure , 07°37'24"N 66°24'48"W, 21 Apr 2010, C. Oliveira & V. Tagliacollo.

Figures

FIGURE 2. Mylossoma albiscopum premaxillary (pmx) and dentary (den), INPA 45467, Careiro da Várzea, lagos do Catalão, Amazonas, Brazil.

FIGURE 4. Mylossoma albiscopum, lectotype of Myletes albiscopus, ANSP 8021, 160 mm TL, río Ambyiacu, Peru. Right side, reversed. Photo by Kyle Luckenbill.

FIGURE 5. Mylossoma albiscopum, LBP 10144, 242 mm SL, rio Abunã, rio Madeira basin, Porto Velho, Rondônia.

FIGURE 6. Mylossoma albiscopum, radiograph of the lectotype of Myletes albiscopus, ANSP 8021, showing (a) premaxilla projected forward,(b) first dorsal-fin ray reduced in size and(c) ventral serra attached to the anal fin or almost so. Radiography by Kyle Luckenbill.

FIGURE 7. Mylossoma albiscopum, INPA 20336, 46 mm SL, juvenile, rio Solimões, Amazonas, Brazil, showing pattern of darkish bands on flanks and round blotch below dorsal fin.

FIGURE 8. Mylossoma albiscopum, LBP 21833, 95 mm SL, rio Negro, Amazonas, Brazil, specimen freshly collected.

FIGURE 9. Mylossoma albiscopum, freshly collected, marginal lake at rio Amazonas, Oriximiná, Pará, Brazil, not preserved. Photo by Jonathan Ready.

FIGURE1. Mylossoma albiscopum, freshly collected,126 mm SL, IgarapéBelmont, right margin of rio Madeira, downstream the CachoeiraSanto Antônio(nowadays UHE SantoAntônio), 08°38'36''S 63°51'05''W, not preserved.Photo by Bruno Barros.

FIGURE3. Geographic distributionof the four Cis-Andean Mylossomaspecies.One dot may represent more than one locality. Red circles: M. albiscopum; yellow triangles: M. aureum; purple squares: M. duriventre; orange diamonds: M. unimaculatum. Mylossoma aureum is also recorded for the Río Orinoco basin (see text).