Biogeography of Amazonian fishes: deconstructing river basins as biogeographic units

ABSTRACT Biogeography of Amazonian fishes (2,500 species in vastly disjunct lineages) is complex and has so far been approached only partially. Here, we tackle the problem on the basis of the largest database yet on geographical distribution and phylogenetic relationships of Amazonian fishes, including all information available. Distributions of 4,095 species (both Amazonian and outgroups) and 84 phylogenetic hypotheses (comprising 549 phylogenetically-informative nodes) were compiled, qualified and plotted onto 46 areas (29 Amazonian and 17 non-Amazonian). The database was analyzed with PAE, CADE, BPA and BPA0, yielding largely congruent results and indicating that biogeographic signal is detectable on multiple dimensions of fish distribution, from single species ranges to cladistic congruence. Agreement is especially pronounced in deeper components, such as Trans-Andean, Cis-Andean, Western Amazon and Orinoco basins. Results show that all major Amazonian tributaries, as well as the Amazon basin itself, are non-monophyletic and constitute hybrid sets of heterogeneous biotic partitions. Amazonian drainages should not be assumed a priori as historically cohesive areas, contrary to widespread practice. Our hypothesis allows re-evaluation of broader issues in historical biogeography, such as the predictive power of biogeographic hypotheses, the vicariant/dispersal duality, the significance of widely distributed taxa, and the need for temporal dimension in biogeographic patterns

Distribution & biogeographical patterns of Amazon fishes.

163 pages : illustrations (chiefly color), color maps ; 26 cm.We provide a general compilation of the diversity and geographical distribution of Amazonian fishes, updated to the end of 2018. Our database includes documented distributions of 4214 species (both Amazonian and from surrounding basins), compiled from published information plus original data from ichthyological collections. Our results show that the Amazon basin comprises the most diverse regional assemblage of freshwater fishes in the world, with 2716 valid species (1696 of which are endemic) representing 529 genera, 60 families, and 18 orders. These data permit a view of the diversity and distribution of Amazonian fishes on a basinwide scale, which in turn allows the identification of congruent biogeographical patterns, here defined as the overlapping distributions of two or more lineages (species or monophyletic groups). We recognize 20 distinct distributional patterns of Amazonian fishes, which are herein individually delimited, named, and diagnosed. Not all these patterns are associated with identifiable geographical barriers, and some may result from ecological constraints. All the major Amazonian subdrainages fit into more than one biogeographical pattern. This fact reveals the complex history of hydrographical basins and shows that modern basin-defined units contribute relatively little as explanatory factors for the present distributions of Amazonian fishes. An understanding of geomorphological processes and associated paleographic landscape changes provides a far better background for interpreting observed patterns. Our results are expected to provide a framework for future studies on the diversification and historical biogeography of the Amazonian aquatic biota

Bryconamericus pinnavittatus Dagosta & Netto-Ferreira, 2015, new species

<i>Bryconamericus pinnavittatus,</i> new species <p>Figure 1; Table 1</p> <p> <b>Holotype.</b> MZUSP 115349, 27.4 mm SL, Brazil, Pará State, Jacareacanga Municipality, stream affluent of the right margin of the rio Teles Pires, downstream of Sete Quedas, 09°18’52’’S 56°46’54’’W, 15 Jan 2008, col. M.V. Loeb & A. de Castro.</p> <p> <b>Paratypes.</b> All from Brazil, Pará State, Jacareacanga Municipality, rio Tapajós basin. MZUSP 98257, 2, 22.5–23.2 mm SL, same date as holotype. MZUSP 98282, 4, 21.4–24.0 mm SL; MPEG 30443, 3, 20.4–22.3 mm SL, right margin of rio Teles Pires, dowstream of Sete Quedas, 09°19’01’’S 56°46’46’’W, 15 Jan 2008, col. M.V. Loeb & A. de Castro. MZUSP 99568, 1, 21.6 mm SL, left margin of rio Teles Pires, 09°17’57’’S 56°47’32’’W, 23 Mar 2008, col. R. Hilário. MZUSP 99943, 6, 22.2–25.7 mm SL, 1 c&s, 24.3 mm SL, 1 M, 27.1 mm; MPEG 30444, 1 c&s, 25.2 mm SL, rio Teles Pires, upstream of Sete Quedas, 09°20’38’’S 56°46’42’’W, 10 Jun 2008, col. L.M. Sousa & A.L. Netto-Ferreira.</p> <p> <b>Diagnosis.</b> <i>Bryconamericus pinnavittatus</i> differs from all congeners, except <i>B. bolivianus</i> Pearson, <i>B</i>. <i>cismontanus</i> Eigenmann, <i>B</i>. <i>deuterodonoides</i> Eigenmann, <i>B</i>. <i>grosvenori</i> Eigenmann, <i>B</i>. <i>hyphesson</i> Eigenmann, <i>B</i>. <i>lambari</i> Malabarba & Kindel, <i>B</i>. <i>macrophthalmus</i> Román- Valencia, <i>B</i>. <i>ornaticeps</i> Bizerril & Perez-Neto, <i>B</i>. <i>patriciae</i> da Silva, <i>B</i>. <i>rubropictus</i> (Berg), <i>B</i>. <i>tenuis</i> Bizerril & Auraujo, and <i>B</i>. <i>thomasi</i> Fowler, by having 11–13 branched anal-fin rays (<i>vs</i>. 15 or more). The new species can be distinguished from <i>B. bolivianus</i>, <i>B</i>. <i>deuterodonoides</i>, <i>B</i>. <i>grosvenori</i>, <i>B</i>. <i>hyphesson</i>, <i>B</i>. <i>lambari</i>, <i>B</i>. <i>ornaticeps</i>, <i>B</i>. <i>patriciae</i>, <i>B</i>. <i>rubropictus</i>, <i>B</i>. <i>tenuis</i>, and <i>B</i>. <i>thomasi</i> by the presence of two maxillary teeth (<i>vs</i>. three or more), from <i>B</i>. <i>cismontanus</i> by the presence of four outer premaxillary teeth (<i>vs.</i> 5 or 6), and from <i>B</i>. <i>macrophthalmus</i> by the lower number of perforated lateralline scales (34–38 <i>vs</i>. 40–41).</p> <p> <b>Description.</b> Morphometric data of holotype and 17 paratypes are given in Table 1. Greatest body depth at vertical through dorsal-fin origin. Head pointed anteriorly in lateral view. Dorsal profile of head convex from tip of snout to vertical through posterior nostril, slightly convex from that point to distal tip of supraoccipital spine; body profile slightly convex from latter point to origin of dorsal fin, straight along dorsal-fin base, concave from dorsalfin base terminus to anteriormost dorsal caudal-fin procurrent ray. Ventral profile of head and body convex from tip of lower lip to pelvic-fin insertion, slightly concave from that point to anal-fin origin, straight along anal-fin base and concave from anal-fin terminus to anteriormost ventral caudal-fin procurrent ray.</p> <p>Mouth subterminal, upper jaw longer than lower jaw. Premaxillary teeth in two rows. Outer row with 3(1), 4*(18), or 5(1) conical or tricuspid teeth. Inner row with 4*(20) tri- to pentacuspid teeth. Maxilla with 2*(20) tri- to pentacuspid teeth; anteriormost tooth largest. Medial dentary tooth pentacuspid, dentary with 4*(19) or 5(1) larger pentacuspid teeth, teeth decreasing in size from mesialmost tooth to lateral ones, followed by 2(2) minute conical or tricuspid teeth. First gill arch with 2(2) gill-rakers on hypobranchial, 6(2) on ceratobranchial, 1(2) on intermediate cartilage, and 4(2) on epibranchial. Branchiostegal rays 4(2).</p> <p> Scales cycloid, <i>circulii</i> restricted to anterior, covered area of scales, with few (around 4-6) divergent <i>radii</i> extending to posterior margin of scales. Lateral line slightly curved ventrally, with 34(5), 35(4), 36(2), 37*(3) or 38(1) perforated scales. Longitudinal scale rows between dorsal-fin origin and lateral line 4(12) or 5*(6); longitudinal scale rows between lateral line and pelvic-fin origin 3*(18). Predorsal scales 11*(12) or 12(6). Circumpeduncular scales 12*(13). Single row of 4 to 6 elongate scales at the base of anal- fin rays.</p> <p>Pectoral-fin rays i,11(8) or i,12*(10). Tip of pectoral fin not reaching vertical through pelvic-fin insertion. Pelvic-fin rays i,5,i(1) or i,6,i*(17). Tip of pelvic fin reaching vertical through anal-fin insertion. Rod-like shaped supraneurals 5(2), anterior to 5th(2) to 9th(2) vertebral centra. Dorsal-fin rays ii,8*(20). First dorsal-fin pterygiophore inserted behind neural spine of 10th(2) vertebral centrum. Distal margin of expanded dorsal fin slightly convex. Dorsal-fin base on middle of body; base terminus anterior to vertical through anal-fin origin. Analfin rays iii*(18); 11(4), 12*(11) or 13(3). Distal margin of anal fin concave. First anal-fin pterygiophore inserted posterior to haemal arch of 16th(2) vertebral centrum. Adipose fin present. Caudal fin forked, lobes approximately similar in size. Principal caudal-fin rays i,9/8,i*(20). Dorsal procurrent caudal-fin rays 12(2), ventral procurrent caudal-fin rays 11(2). Total vertebrae 35(2); precaudal vertebrae 16(2), caudal vertebrae 19(2).</p> <p> <b>Color in alcohol.</b> Overall ground color pale yellowish (Fig. 1). Infraorbital, opercular, and gular areas retaining intense guanine deposition in some specimens. Head dark, densely pigmented in dorsal view. Snout tip to nares with scattered chromatophores. Midline dorsal scales from posterior tip of supraoccipital to anteriormost dorsal caudal-fin procurrent ray bordered with dark chromatophores. Few sparse dark chromatophores on upper portion of opercle. Premaxilla and anterior half of maxilla with few scattered chromatophores. Vertically elongate humeral blotch, encompassing 2 scales horizontally and 3 vertically, including scales of lateral line series. Borders of humeral blotch diffuse. Body pigmented by scattered small dark chromatophores, more intense dorsal to midlateral septum. Dark chromatophores following the myosepta from vertical through middle of dorsal-fin to caudal peduncle. Dark chromatophores from middle portion of second unbranched ray to third branched ray and distal portion of remaining posterior dorsal-fin rays forming a diffuse band on dorsal fin. Diffuse dark band from middle portion of interadial membranes of first unbranched anal-fin ray to third branched ray extending to distal portion of remaining posterior rays. Pectoral, pelvic and adipose fins hyaline. Base of caudal-fin rays with intense concentration of dark cromatophores. Outermost caudal-fin rays with cromatophores along its entire length. Distal portion of all caudal-fin rays pigmented. Median caudal-fin rays lacking pigment on its middle portion, forming an unpigmented area and more evident on upper than on lower caudal-fin lobe.</p> <p> <b>Etymology.</b> The specific name <i>pinnavittatus</i>, derives from the latin <i>pinna</i> (= fin) and <i>vittatus</i> (= adorned with a ribbon), referring to the pigmented vertical band present at the base of caudal-fin rays.</p> <p> <b>Sexual dimorphism.</b> Pelvic-fin hooks were observed in one specimen (MZUSP 99943). Hooks were present on the middle portion of first to fourth innermost branched pelvic-fin rays.</p> <p> <b>Distribution.</b> <i>Bryconamericus pinnavittatus</i> is only known from its type locality in the lower rio Teles Pires, rio Tapajós basin (Fig. 2).</p>Published as part of <i>Dagosta, Fernando C. P. & Netto-Ferreira, André L., 2015, New species of Bryconamericus Eigenmann (Characiformes: Characidae) from the rio Teles Pires, rio Tapajós basin, central Brazil, pp. 433-442 in Zootaxa 3911 (3)</i> on pages 434-437, DOI: 10.11646/zootaxa.3911.3.9, <a href="http://zenodo.org/record/237692">http://zenodo.org/record/237692</a&gt

New species of Bryconamericus Eigenmann (Characiformes: Characidae) from the rio Teles Pires, rio Tapajós basin, central Brazil

Dagosta, Fernando C. P., Netto-Ferreira, André L. (2015): New species of Bryconamericus Eigenmann (Characiformes: Characidae) from the rio Teles Pires, rio Tapajós basin, central Brazil. Zootaxa 3911 (3): 433-442, DOI: http://dx.doi.org/10.11646/zootaxa.3911.3.

A new species of Moenkhausia Eigenmann (Characiformes: Characidae) from the rio Arinos basin, Brazil

ABSTRACT A new species of Moenkhausia is described from the rio Arinos drainage, rio Tapajós basin, Mato Grosso, Brazil. The new species is diagnosed from all congeners, except M . hemigrammoides , M . nigromarginata , and Moenkhausia rubra by having intense diffuse dark pigmentation on the dorsal and anal fin-rays. The new species can be distinguished from the above mentioned species by the combination of 20-23 branched anal-fin rays, presence of a vertically elongate roughly rectangular humeral spot surpassing the lateral line ventrally, absence of a well-defined black spot on the distal portion of the dorsal fin and lack of a series of longitudinal dark zigzag stripes on body. The new species is herein described along with a report and discussion of a possible connection between the rio Tapajós and rio Paraguay basins, near Diamantino Municipality, Mato Grosso