Astyanax multidens Eigenmann, 1908

Marinho, Manoela M. F. & Birindelli, José L. O., 2013, Redescription of Astyanax multidens Eigenmann, 1908 (Characiformes: Characidae), a small characid of the Brazilian Amazon, Neotropical Ichthyology 11 (1), pp. 45-54 : 46-51

Astyanax multidens Eigenmann, 1908

Figs. 1-4

Astyanax multidens Eigenmann, 1908: 98 [Óbidos and Silva (=Silves), Lake Saraca].- Eigenmann, 1910: 434 [citation].- Eigenmann, 1921: plate 50, fig. 4 [illustration].- Eigenmann, 1927: 323 [literature compilation].- Eigenmann, 1927: 328 [literature compilation; considered to be allied to A. guianensis ].- Fowler, 1943: 3 [similarity to A. chaparae ].- Fowler, 1948: 55-56 [literature compilation; in part, not rio Paraguay].- Géry, 1977: 426 [identification key].- Vari & Howe, 1991: 7 [catalogue of type specimens].- Lima et al., 2003: 111 [literature compilation].- Lima et al., 2007: 46 [literature compilation].

Diagnosis. Astyanax multidens is distinguished from all congeners except A. angustifrons (Regan) , A. aurocaudatus Eigenmann , A. gisleni Dahl , A. goyanensis (Miranda Ribeiro), A. guaporensis Eigenmann , A. guianensis Eigenmann , A. henseli Melo & Buckup , A. leopoldi Géry, Planquette & Le Bail , A. nasutus Meek , A. nicaraguensis Eigenmann , A. superbus Myers , and A. totae Haluch & Abilhoa by having five to seven maxillary teeth (vs. less than five). Astyanax multidens is distinguished from the aforementioned species, except A. angustifrons , A. guaporensis , A. guianensis , A. leopoldi , A. nicaraguensis , and A. totae by having 31 to 34 pored lateral-line scales (vs. more than 34). Astyanax multidens is distinguished from A. totae and A. nicaraguensis by having 20 to 23 branched anal-fin rays (vs. 15 to 18 and 24 to 29, respectively); from A. angustifrons and A. leopoldi by the absence of a dark blotch on the caudal peduncle (vs. presence); and from A. guaporensis and A. guianensis by having a dark triangular blotch on middle caudal-fin rays (vs. middle caudal-fin rays hyaline).

Description. Morphometrics presented in Table 1. Overall body size small (largest examined specimen 52.8 mm SL). Body compressed, moderately elongate. Greatest body depth slightly anterior to dorsal-fin origin. Dorsal profile of head convex from upper lip to vertical through anterior nostril; straight from that point to tip of supraoccipital spine. Dorsal profile of body slightly convex along predorsal region, straight and posteroventrally inclined along dorsal-fin base, straight to slightly convex from terminus of dorsal-fin base to adipose-fin origin, and concave along caudal peduncle. Ventral profile of head and body convex from tip of lower jaw to anal-fin origin, straight and posterodorsally inclined along anal-fin base, and concave along caudal peduncle.

Jaws equal, mouth terminal. Premaxillary teeth in two rows ( Fig. 3 ). Outer row with 2*(3), 3*(23), 4*(8), or 5*(2) tricuspid teeth. Inner row with 5*(32) or 6 (2) tri- to pentacuspid teeth. Tip of maxilla slightly posterior of vertical through anterior margin of eye, with 5*(21), 6 (9), or 7 (8) uni- to tetracuspid teeth. Dentary with 4* large pentacuspid, one tricuspid and series of 6-10 small uni- to tricuspid teeth. Central median cusp in all teeth longer than lateral cusps. Branchiostegal rays 4. First gill arch with 2 (2) or 3 (2) hypobranchial, 9 (2) or 10 (2) ceratobranchial, 1 intermediate cartilage, and 6 (3) or 7 (1) epibranchial gill rakers. Each gill raker with small denticles on its length.

Scales cycloid, with few radii on posterior border. Lateral line straight to slightly curved ventrally, with 31*(2), 32*(3), 33*(18) or 34 (14) perforated scales from supracleithrum to caudal-fin base. Longitudinal scale rows between dorsal-fin origin and lateral line 5 (33) or 6 (4). Longitudinal scale rows between lateral line and pelvic-fin origin 3*(3), 4*(28) or 5*(6). Predorsal scales 8 (1), 9 (18), or 10* (14) in one series. Row of 5 (8), 6 (8), 7 (9), or 8 (3) scales at base of anteriormost anal-fin rays. Circumpeduncular scale rows 14. Caudal fin with scales along basal one-sixth of upper lobe and basal one-fourth of lower lobe.

Pectoral-fin raysi,11*(2), i,12*(9), i,13 (15), i,14 (7), or i,15 (1). Tip of adpressed fin at pelvic fin-origin or falling slightly short of that point. Pelvic-fin rays i,7*(33) or i,8 (1). Tip of adpressed fin at anal-fin origin or falling slightly short. Supraneurals 3 (1) or 4 (3). Dorsal-fin origin at middle of SL and slightly posterior to vertical through pelvic-fin origin. Dorsal-fin rays ii,9. First unbranched ray about one-half length of second unbranched ray. Base of last dorsal-fin ray slightly anterior to vertical through anal-fin origin. First dorsal-fin pterygiophore inserted behind neural spine of 5 th vertebra. Adipose-fin origin at vertical through base of 16 th to 18 th branched anal-fin rays.Anal-fin rays iv,20 (1), iv,21*(17), iv,22 (12), or iv,23*(4). First anal-fin pterygiophore inserted behind haemal spine of 12 th (3) or 13 th (1) vertebra. Caudal-fin rays i,9,8,i*. Caudal fin forked, with lobes of similar size. Dorsal procurrent caudal-fin rays 11 (3) or 12 (1); ventral procurrent caudal-fin rays 11 (4). Total vertebrae 32 (4): precaudal vertebrae 15 and caudal vertebrae 17.

Color in alcohol. Overall ground color yellowish. Opercular area silvery. Lips, anterior portion of maxilla, and dorsal portion of head with small dark chromatophores. Larger chromatophores on upper one-half of opercle. Scales of two or three dorsalmost longitudinal scale rows bordered by dark pigmentation. Humeral blotch conspicuous, vertically oriented, from one scale row ventral of, and three scale rows dorsal of lateral line, and over three scales horizontally. Lower half of humeral spot often interrupted by clear horizontal area. Clear area between humeral blotch and posterior pigmented area that fades longitudinally. Stripe extending over four or five longitudinal scale rows dorsal to lateral line, and from vertical through 7 th or 8 th lateral line scale to caudal peduncle. Dark pigmentation along horizontal septum, approximately from vertical through dorsal-fin origin to caudal peduncle. Clear area anterior to caudal-fin base. Pectoral, pelvic and adipose fins with scattered dark chromatophores. First unbranched dorsal-fin ray with dark chromatophores; remaining rays hyaline. Distal portion of interadial membranes of all dorsal-fin rays with scattered dark chromatophores.Anal fin with scattered small chromatophores. Chromatophores frequently concentrated at proximal and distal portions of interadial membranes. Caudal fin with somewhat and sometimes diffuse triangular blotch on middle rays. Anterior margin of blotch straight; posterior pointed. Caudal-fin lobes hyaline or with scattered dark chromatophores.

Color in life. Coloration in life similar to described above for preserved specimens, except for dorsal portion of iris red, distal portion of anteriormost rays of dorsal, pelvic and anal fins white, adipose fin red, and caudal fin with pale orange blotch immediately dorsal and ventral to dark median blotch ( Fig. 4 ).

Sexual dimorphism. No sexually dimorphic modification was observed.

Distribution. Astyanax multidens is known from the rio Amazonas at Silves, State of Amazonas, and Óbidos, State of Pará, and the rios Trombetas, Tapajós, Xingú and Araguaia ( Fig. 5 ).

Remarks. During the Thayer Expedition, James collected 40 specimens of small characids at Óbidos, which were kept in a single jar and catalogued as MCZ 20840. Eigenmann (1908, 1918, 1927) recognized two distinct species among these specimens, electing 5 specimens as paratypes of Hemigrammus microstomus and 35 as paratypes of Astyanax multidens . Later, the 35 syntypes of Astyanax multidens were removed to MCZ 89559 (the five paratypes of Hemigrammus microstomus remained as MCZ 20840). During this process, the 35 syntypes of Astyanax multidens received the informal number MCZ 21064a, in reference to the other syntype from lago Saraca, catalogued as MCZ 21064. Six of the 35 syntype were then exchanged to USNM (USNM 120244). The others 29 syntypes remained catalogued as MCZ 89559. Thus, the syntypes of Astyanax multidens are MCZ 21064 (1), MCZ 89559 (29) and USNM 12044 (6).

Eigenmann (1927) cited a single specimen (MCZ 20826, Fig. 1c ) as “probably identical with” the type specimens of Astyanax multidens . Our examination confirm Eigenmann’s (1927) suggestion that the aforementioned specimen is indeed conspecific with the syntypes of Astyanax multidens .

Examinations of the type series of Moenkhausia collettii deposited at the NMW revealed that part of the syntypes from Óbidos (NMW 57382, 5), is conspecific with Astyanax multidens . Astyanax multidens can be promptly distinguished from Moenkhausia collettii by having a the middle caudal-fin rays dark (vs. middle caudal-fin rays hyaline), 5 to 7 maxillary teeth (vs. 1 to 3), scales restricted to the base of the caudal fin, along basal one-sixth of upper lobe and basal one-fourth of lower lobe (vs. along one-fourth of the upper lobe and half of the lower lobe) and by the absence of a black line on the anal-fin base (vs. presence). Since the type series of Moenkhausia collettii is composed of more than one species, a lectotype designation of that species is in need. However, this is beyond of the scope of the present contribution, as it should be done in a separate study about the taxonomy and distribution of M. collettii . Noteworthy to say that Steindachner (1882) described the maxilla as edentulous in the original description of M. collettii and also illustrated a specimen with middle caudal-fin rays hyaline, features not present in specimens of Astyanax multindes .

Although Bertoni (1939) and Fowler (1948) mentioned Astyanax multidens for the upper rio Paraguay, their reports are doubtful since the extensive material analyzed from that drainage do not have any specimens of Astyanax multidens . Géry (1977: 426) also mentioned Astyanax multidens , referring it to his “ Astyanax - paucidens group”, which also includes other poorly known species such as A. scintillans Myers, 1928 , A. guaporensis , A. guianensis , A. paucidens (Ulrey, 1894) , A. gracilior Eigenmann, 1908 , A. kennedyi Géry, 1964 , and A. essequibensis Eigenmann, 1909 [= Jupiaba essequibensis ].

Material examined. Brazil. ANSP 191047, 5, 34.2-41.8 mm SL; DZSJRP 12546, 5, 32.4-44.1 mm SL; INPA 33987 5, 33.0- 44.3 mm SL; MCP 44598, 5, 31.7-43.3 mm SL; MNRJ 37225, 5, 31.8-43.3 mm SL; MZUSP 96606, 75, 27.3-45.3 mm SL, Mato Grosso, Peixoto de Azevedo, rio Peixoto de Azevedo, tributary of rio Teles Pires, rio Tapajós basin, 10°13’14”S 54°58’2”W. MCZ 21064, 1, 29.9 mm SL, syntypes of Astyanax multidens Eigenmann,1908 , “Silva, Lake Saraca” (=Amazonas, lago Saraca at Silves, 2º53’S 58º21’W]. MCZ 89559, 29; USNM 120244, 6, 26.1-30.6 mm SL, syntypes of Astyanax multidens Eigenmann, 1908 , “Óbidos”, (=Amazonas, Óbidos, rio Amazonas, 1º52’S 55º30’W). MCZ 20826, 1, 36.3 mm SL, same data as MCZ 89559. MZUSP 5454, 12, 32.5-37.0 mm SL, Pará, Oriximiná, rio Trombetas basin. MZUSP 52228, 27, 24.8-29.9 mm SL, Tocantins, Sandolândia, rio Água Fria, rio Araguaia basin. MZUSP 74635, 10, 16.2-24.8 mm SL, Mato Grosso, São José do Xingu, rio Preto, tributary of rio Xingu. MZUSP 91706, 23, 16.2-33.9 mm SL, Mato Grosso, Paranatinga, rio Culuene, tributary of rio Xingu. MZUSP 91215, 2, 21.9 and 25.8 mm SL, Mato Grosso, Bom Jesus do Araguaia, rio Suiazinho, tributary of rio Suiá-Miçu, rio Xingu basin, 12°27’25”S 51°45’35”W. MZUSP 91226, 1, 20.7 mm SL, Mato Grosso, Canarana, rio Sete de Setembro, tributary of rio Xingu, 13°30’19”S 52°24’57”W. MZUSP 91369, 2, 22.3 and 22.7 mm SL, Mato Grosso, Gaúcha do Norte, rio Curisevo, tributary of rio Xingu, 13°2’5”S 53°25’19”W. MZUSP 91738, 2, 25.0 and 25.6 mm SL, Mato Grosso, Paranatinga, rio Culuene, 13°50’21”S 53°15’13”W. MZUSP 91800, 2, 22.9 and 32.0 mm SL, Mato Grosso, Paranatinga, rio Culuene, tributary of rio Xingu, 14°0’32”S 53°20’46”W. MZUSP 91955, 54, 14.9-25.1 mm SL, Mato Grosso, Paranatinga, rio Culuene, tributary of rio Xingu, 13°49’S 53°15’W. MZUSP 94171, 3, 20.4- 26.8 mm SL, Mato Grosso, Paranatinga, rio Culuene, tributary of rio Xingu, 13°50’S 53°15’W. MZUSP 94251, 11, 18.5-23.8 mm SL, Mato Grosso, Paranatinga, rio Culuene, tributary of rio Xingu, 13°50’22"S 53°14’59”W. MZUSP 94284, 20, 18.8-24.5 mm SL, Mato Grosso, Paranatinga, rio Culuene, tributary of rio Xingu, 13°35’49”S 53°6’35”W. MZUSP 94339, 46, 17.0- 27.4 mm SL, Mato Grosso, Paranatinga, rio Culuene, tributary of rio Xingu, 13°30’51”S 53°5’49”W. MZUSP 94410, 4, 17.0- 17.3 mm SL, Mato Grosso, Paranatinga, rio Culuene, tributary of rio Xingu, 13°25’48”S 53°2’24”W. MZUSP 95689, 37, 15.7-26.8 mm SL, Mato Grosso, Paranatinga, ribeirão da Anta, tributary of rio Culuene, rio Xingu basin, 13°30’53”S 53°5’34”W. MZUSP 95954, 2, 30.4 and 31.3 mm SL, Mato Grosso, Itaúba, Teles Pires drainage, tributary of rio Renato, rio Tapajós basin, 11°5’42”S 55°3’54”W. MZUSP 96726, 133, 24.4- 39.5 mm SL, 2 cs, 34.4 and 34.8 mm SL, Mato Grosso, Paranaíta, rio Teles Pires, near ferryboat of road MT-416, rio Tapajós basin, 9°27’7”S 56°30’46”W. MZUSP 96727, 88, 25.7-37.7 mm SL, Mato Grosso, Paranaíta, marginal remaining lagoons from mining activities, rio Tapajós basin, 9°25’44”S 56°32’36”W. MZUSP 96730, 26, 31.9- 38.9 mm SL, Pará, Jacareacanga, rio Teles Pires downstream of Sete Quedas rapids, rio Tapajós basin, 9°19’1”S 56°46’47”W. MZUSP 96745, 29, 33.1-48.5 mm SL, Mato Grosso, Peixoto de Azevedo, tributary of right margin of rio Peixoto de Azevedo, rio Tapajós basin, 10°17’14”S 54°50’57”W. MZUSP 96907, 43, 19.0- 25.9 mm SL, Mato Grosso, Paranatinga, córrego do Lício, tributary of rio Culuene, rio Xingu basin, 13°50’22”S 53°14’59”W. MZUSP 97205, 2, 24.1 and 24.8 mm SL, Pará, Altamira, rio Curuá, tributary of rio Iriri, rio Xingu basin, 8°19’7”S 55°5’23”W. MZUSP 97249, 185, 25.3-52.8 mm SL, 2 cs, 44.2 and 44.3 mm SL, Pará, Novo Progresso, rio Jamanxim, tributary of rio Tapajós, about 30 km from Castelo dos Sonhos, 8°11’4”S 55°21’28”W. MZUSP 97307, 37, 26.6-41.7 mm SL, Pará, Novo Progresso, rio Jamanxim, tributary of rio Tapajós, near village of Mil, 7°43’51”S 55°16’36”W. MZUSP 97407, 13, 22.8-23.5 mm SL, Mato Grosso, Paranatinga, rio Culuene, tributary of rio Xingu, 13°49’46”S 53°15’6”W. MZUSP 97475, 34, 26.1-33.4 mm SL, Pará, Novo Progresso, rio Jamanxim, tributary of rio Tapajós, at beach near city, 7°3’52”S 55°26’28”W. MZUSP 99600, 31, 17.5- 35.8 mm SL, Mato Grosso, Paranaíta, left margin of rio Teles Pires, rio Tapajós basin, 9°27’6”S 56°30’44”W. MZUSP 99818, 8, 21.7- 30.0 mm SL, Pará, Jacareacanga, rio Teles Pires, downstream of Sete Quedas rapids, rio Tapajós basin, 9°19’56”S 56°46’33”W. MZUSP 99845, 8, 18.6-24.7 mm SL, Pará, Jacareacanga, rio Teles Pires, downstream of Sete Quedas rapids, rio Tapajós basin, 9°18’42”S 56°46’47”W. MZUSP 99960, 16, 22.1-41.0 mm SL, Pará, Jacareacanga, rio Teles Pires, downstream of Sete Quedas rapids, rio Tapajós basin, 9°20’38”S 56°46’42”W. MZUSP 100037, 11, 20.8-31.7 mm SL, Mato Grosso, Paranaíta, rio Teles Pires, upstream of Sete Quedas rapids, rio Tapajós basin, 9°23’53”S 56°34’37”W. MZUSP 100100 (41, 17.9-26.6 mm SL), Pará, Jacareacanga, rio Teles Pires, upstream of Sete Quedas rapids, rio Tapajós basin, 9°24’5”S 56°33’49”W. MZUSP 104495, 9, 18.0- 22.9 mm SL, Mato Grosso, ribeirão Cascalheira, rio Turvo, tributary of rio Suiá-Miçu, rio Xingu basin. MZUSP 110938, 2, 26.3 and 28.6 mm SL, Pará, Altamira, rio Iriri, tributary of rio Xingu, at Cachoeira Grande, 3°52’8”S 52°41’52”W. MZUSP 110939, 68, 21.1-31.5 mm SL, Pará, Altamira, rio Xingu, 3°42’32”S 52°27’11”W. MZUSP 110940, 268, 20.5-30.6 mm SL, Pará, Altamira, rio Xingu, 3°38’14”S 52°21’53”W. MZUSP 110941, 1, 30.9 mm SL, Pará, Altamira, rio Xingu, 3°24’39”S 51°44’50”W. MZUSP 110943, 18, 19.8-29.7 mm SL, Pará, Altamira, rio Xingu, 3°14’12”S 52°13’21”W. NMW 57382, 5, syntypes of Tetragonopterus collettii Steindachner, 1882 , 27.8-31.0 mm SL, Óbidos.

Figures

Fig. 1. Astyanax multidens: (a) syntype, MCZ 89559, 29.2 mm SL, rio Amazonas at Óbidos, (b) syntype, MCZ 89559, 30.0 mm SL, rio Amazonas at Óbidos, (c) MCZ 20826, 36.3 mm SL, rioAmazonas at Óbidos.

Fig. 2. Astyanax multidens: (a) MZUSP 96606, 44.6 mm SL, rio Peixoto de Azevedo, tributary of rio Teles Pires, (b) MZUSP 99818, 29.5mm SL, rio TelesPires, (c) MZUSP94171,25.7 mm SL, rio Culuene, tributary ofrio Xingu,(d)MZUSP 52228,25.2 mm SL, rio Água Fria, rioAraguaia basin.

Fig. 3. Upper and lower jaws of Astyanax multidens (lateral view, right side), MZUSP 96726, 44.3 mm SL. Scale bar 1 mm.

Fig. 4. Astyanax multidens, photographed live, MZUSP 91955, ca. 25 mm SL, rio Culuene, tributary of rio Xingu (photo by Leandro Sousa).

Fig. 5. Distribution of Astyanax multidens in the rio Amazonas basin. White circle represent the type localities.