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Origin of species diversity in the catfish genus Hypostomus (Siluriformes: Loricariidae) inhabiting the Paraná river basin, with the description of a new species

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Within the Loricariidae, the genus Hypostomus is one of the most diversified freshwater catfish groups. Using new sequence data from the mitochondrial Control Region (D-loop) we examined the phylogeny of this genus. Our phylogenetic analyses suggest that, in the Paraná river basin, species diversity in the genus Hypostomus has been shaped by two processes: 1) by inter-basin diversification, generating groups of species that inhabit different basins, as a result of dispersal events; and 2) via intra-basin speciation as a result of basin fragmentation due to past marine transgressions, which produced groups of species within a basin. Using the D-loop as a molecular clock, each event of diversification was dated and linked with documented hydrological events or sea level changes. We also assessed the possible dispersal routes between the Paraná and Uruguay rivers, in addition to the obvious dispersal route via the Río de la Plata estuary. Finally, we describe a new species of Hypostomus inhabiting Middle Paraná river, Hypostomus arecuta n. sp. This species can be separated from all other Hypostomus by having light roundish dots on a darker background and by number of premaxillary/dentary teeth.
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Accepted by M. R. de Carvalho: 23 Jul. 2012; published: 5 Sept. 2012
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Copyright © 2012 · Magnolia Press
Zootaxa 3453: 6983 (2012)
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Article
69
urn:lsid:zoobank.org:pub:16DA5467-36FD-45FE-8984-FD59392C08BE
Origin of species diversity in the catfish genus Hypostomus (Siluriformes: Lori-
cariidae) inhabiting the Paraná river basin, with the description of a new species
YA MI L A P. C A RD O S O1*, ADRIANA ALMIRÓN2, JORGE CASCIOTTA2, DANILO AICHINO3, MARTA S.
LIZARRALDE1 & JUAN I. MONTOYA-BURGOS4.
1 Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Centro Regional de Estudios Genónicos, UNLP, Av.Cal-
chaquí 23,5km, C. C. 1888, Fcio. Varela, Buenos Aires, Argentina.
2 División Zoología Vertebrados, Museo de La Plata, UNLP, Paseo del Bosque, C. C. 1900, La Plata, Argentina.
3 Facultad de Ciencias Exactas Químicas y Naturales, UNAM, Felix de Azara, C.C. 1552, Misiones, Argentina.
4 Department of Genetics and Evolution, University of Geneva, 30 quai Ernest Ansermet, 1211, Geneva 4, Switzerland.
Abstract
Within the Loricariidae, the genus Hypostomus is one of the most diversified freshwater catfish groups. Using new se-
quence data from the mitochondrial Control Region (D-loop) we examined the phylogeny of this genus. Our phylogenetic
analyses suggest that, in the Paraná river basin, species diversity in the genus Hypostomus has been shaped by two proc-
esses: 1) by inter-basin diversification, generating groups of species that inhabit different basins, as a result of dispersal
events; and 2) via intra-basin speciation as a result of basin fragmentation due to past marine transgressions, which pro-
duced groups of species within a basin. Using the D-loop as a molecular clock, each event of diversification was dated
and linked with documented hydrological events or sea level changes. We also assessed the possible dispersal routes be-
tween the Paraná and Uruguay rivers, in addition to the obvious dispersal route via the Río de la Plata estuary. Finally, we
describe a new species of Hypostomus inhabiting Middle Paraná river, Hypostomus arecuta n. sp. This species can be sep-
arated from all other Hypostomus by having light roundish dots on a darker background and by number of premaxillary/
dentary teeth.
Key words: Armored catfish; Control Region; phylogeny; Paraná river.
Introduction
In South America, the Loricariidae is the most species-rich endemic family of freshwater fishes. This family of
suckermouth-armored catfishes comprises 818 species (Eschmeyer and Fricke, 2011) and new species are
frequently discovered and described (e.g. Hollanda Carvalho et al., 2010; Zawadzki et al., 2010; Rodriguez et al.,
2011; Cardoso et al., in preparation). Within the Loricariidae, the genus Hypostomus constitutes a rich assemblage
of species, with approximately 130 recognized species (Weber, 2003; Ferraris 2007; Zawadzki et al., 2010,
Hollanda Carvalho et al., 2010). Representatives of Hypostomus are bottom-dwelling fishes widely distributed
throughout tropical and subtropical South America, occurring in a variety of freshwater ecosystems such as
mountain streams and large lowland rivers and ponds. Species delineation and diagnosis in Hypostomus is difficult,
in particular due to the diversity and widespread distribution of the genus, to elevated intra-specific morphological
variability, and because some older descriptions are too short or incomplete.
Numerous species of Hypostomus inhabit the La Plata basin, which comprises the Paraguay, Paraná, and
Uruguay rivers and the Río de la Plata (López and Miquelarena, 1991). Understanding the diversification history of
Hypostomus as a "model" genus might allow the development of a comprehensive view of the processes that
shaped the rich ichthyological diversity in the Paraná river basin.
According to the reconstruction of paleo basins in South America, from about 60 to10 million years ago (Ma),
the paleo Amazon–Orinoco system was a large watershed with waters flowing northward toward the Caribbean
Sea, while the La Plata basin was already oriented as present (Lundberg, 1998). This author suggested that at 12–10
CARDOSO ET AL.
70 · Zootaxa 3453 © 2012 Magnolia Press
Ma, the boundary between the paleo Amazon–Orinoco and the La Plata basins underwent a final and important
shift southward to its current location. This boundary displacement must have occasioned exchanges of water and
fishes between the two main basins 12 to 10 Ma, as proposed by Montoya-Burgos (2003). However, the boundary
displacement might have been more progressive, covering the last 10 Ma (Rasanen et al., 1995; Lundberg et al.,
1998), opening occasional dispersal routes between these two river systems.
During the Miocene (24-5 Ma), two main components of the La Plata basin, the upper plus middle Paraná river
on one hand, and Uruguay river on the other, which were forming a single large river flowing southward into the
Rio de la Plata estuary, disconnected from one another resulting in the modern configuration (Beurlen, 1970).
According to Bonetto (1994), geological changes caused this disconnection by modifying the course of the middle
Paraná river that subsequently reached the course of the Paraguay river. Today, the Paraná and Uruguay rivers are
connected exclusively via the Río de la Plata estuary.
Furthermore, in the second half of the Miocene, 15-5 Ma, marine transgressions occurred at least twice along
distinct paleogeographic corridors. The first maximum flooding event occurred between 15 and 13 Ma and the
second between 10 and 5 Ma. The two marine transgressions covered most of the Paraná river basin (Hernández et
al., 2005). It is likely that the diversity of strictly freshwater organisms might have been seriously impacted by
these marine transgressions. For example, the museum hypothesis of diversification (Nores, 1999) states that the
Miocene marine incursions have been major diversifying events via the fragmentation of emerged land resulting in
allopatric speciation.
The goals of the present work are: (1) to expand the phylogeny of the genus Hypostomus that was previously
proposed by Montoya-Burgos (2003) using new sequence data from the mitochondrial Control Region, (2) to infer
the origin of the diversity of Hypostomus species in the Paraná river basin, (3) to assess the possible dispersal
routes between the Paraná and Uruguay river, in addition to the obvious dispersal route via the Río de la Plata
estuary, and (4) to describe a new species of Hypostomus inhabiting the Middle Paraná river basin.
The use of genetic markers is a powerful tool to estimate the extent of hidden biodiversity. For example, the
mitochondrial D-loop region is frequently used for answering a broad range of biological questions relative to
population processes, phylogeography (e.g. Cardoso and Montoya-Burgos, 2009) and species identification (e.g.
Cardoso et al., 2011). Here we used this molecular tool in order to infer the phylogenetic relationships among
Hypostomus species and to analyse the origin of species diversity in the río Paraná basin.
Materials and methods
Taxon sampling and morphological analyses
Fish specimens were collected in 15 different localities in the Paraná river basin, Argentina (Fig. 1). Most of them
were sampled in the middle and lower section of the Paraná river basin. We also used available data from the upper
section of this basin taken from GenBank. Fishes were caught using gill nets, cast nets, hand nets, and seine. Tissue
samples for genetic studies were preserved in ethanol 96 % and frozen at -20 °C, the vouchers specimens were
fixed in formalin 10 % for morphological studies and deposited at MHNG, IPLA, and MACN according to the
institutional abbreviations are as listed in Ferraris (2007). Table I has more information about the specimens
analysed.
All measurements were taken point to point with digital calipers to the nearest 0.01 mm, under a dissecting
microscope when necessary. Measurements and counts of bilaterally symmetrical features were taken from the left
side of the body whenever possible; if a feature was missing or broken on the left side, it was examined on the right
side. Counts and measurements follow Boeseman (1968), Weber (1985), and Reis et al. (1990). Body plate counts
and nomenclature follow Oyakawa et al. (2005). The oral disk width was measured at point of insertion of the
maxillary barbels.
DNA amplification and sequencing
The genomic DNA was extracted using the salt-extraction protocol (Aljanabi and Martinez, 1997). The PCR
amplification of the Control Region (D-loop) of the mitochondrial DNA was performed using the following primers:
DLA-III 5’-TATT TAAAGRCATAATC TCTTGAC-3’ and HygDL-R 5’–WTGCKARTATGTGCCGYYTG–3’. The
amplifications were performed in a total volume of 50 l, containing 5 l of 10x reaction buffer, 1 l of
deoxyribonucleoside triphosphate (dNTP) mix at 10 mM each, 1 l of each primer at 10 M, 0.2 l of Taq DNA
Zootaxa 3453 © 2012 Magnolia Press · 71
ORIGIN OF SPECIES DIVERSITY IN HYPOSTOMUS.
Polymerase equivalent to 1 unit of Polymerase per tube, and 1 l of DNA. Cycles of amplification were programmed
as follows: (1) 3 min. at 94°C (initial denaturing), (2) 30 sec. at 94°C, (3) 30 sec. at 55–57°C, (4) 1 min. at 74°C, and
(5) 5 min. at 74°C (final elongation). Steps 2 to 4 were repeated 42 times. The PCR products were purified and
sequenced by the company MAGROGEN (Korea). Sequences were deposited in GenBank (Table I).
TAB LE I. Details of the specimens used in the molecular phylogeny with GenBank accession numbers.
Species GenBank Field number Locality
H. arecuta JF290442 AG09-163 Yahapé (27º22'12.1"S-57º39'14.6"W)
H. arecuta JF290441 AG09-181 Ituzaingó (27º 29'32''S-56º 39'38''W)
H. arecuta JF290445 AG09-198 Ituzaingó (27º 29'32''S-56º 39'38''W)
H. arecuta JF290446 PR-031 Santa Fé, Santa Fé, Argentina
H. arecuta JF290443 TAE01 Ituzaingó (27º 29'32''S-56º 39'38''W)
H. arecuta JF290444 TAE02 Ituzaingó (27º 29'32''S-56º 39'38''W)
H. derby JF290447 YC10-316 Uruzú (25°55'38.25''S-53°56,031'W)
H. paranensis JF290449 YC-025 Suquia (31°24'11,9''S-64°12'11,4''W)
H. paranensis JF290448 YC-026 Suquia (31°24'11,9''S-64°12'11,4''W)
H. commersoni JF290450 AG09-129 Tabay (26º59'56.3"S-55º10'44.9"W)
H. commersoni JF290451 YC09-124 Manucho (31°15'S- 60°53' W)
H. commersoni JF290452 YC-957 El Bosque (34°54'37.55''S-57°56'15.65''W)
H. commersoni JF290453 YC-607 Corrientes (29°48,574’S-59°23.600’W)
H. commersoni JF290454 14802 P. N. Pre-Delta (32º08'08.8"S- 60º37'26.2"W).
H. commersoni JF290455 AG09-013 Ituzaingó (25º29'54.5"S- 56º42'47.0"W)
H. commersoni JF290456 Reg02 Ensenada (34°50'23,96''S-57°55'13,04''W)
H. commersoni JF290457 AG09-077 Garupa (27º29'10.2"S-55º44'23.1"W)
H. commersoni JF290458 YC-926 El Pescado (34°57,790'S- 57°46,696'W)
H. cochliodon JF290476 AG09-016 Ituzaingó (27º 29'32''S-56º 39'38''W)
H.luteomaculatus JF290471 YC-162 Antequera (27°27'43.43" S-58°52'0.03" W)
H. luteomaculatus JF290469 UR004 Pedra Fortaleza, Itapiranga, Brazil
H. luteomaculatus JF290470 UR002 Pedra Fortaleza, Itapiranga, Brazil
H. luteomaculatus JF290468 AG09-157 Ituzaingó (27º 29'32''S-56º 39'38''W)
H. luteomaculatus JF290467 AG09-200 Ituzaingó (27º 29'32''S-56º 39'38''W)
H. luteomaculatus JF290459 AG09-012 Ituzaingó (27º 29'32''S-56º 39'38''W)
H. luteomaculatus JF290466 CIA283 Candelaria (27º26'92"S-55º44'50"W)
H. microstomus JF290461 AG09-015 Ituzaingó (27º 29'32''S-56º 39'38''W)
H. myersi JF290472 YC10-256 Deseado (25°47'1.30'' S-54°2'21.40'' W)
H.myersi JF290474 AG09-123 Tabay (26º59'56.3"S-55º10'44.9"W)
H. myersi JF290473 AG09-124 Tabay (26º59'56.3"S-55º10'44.9"W)
H. myersi JF290475 AG09-131 Tabay (26º59'56.3"S-55º10'44.9"W)
H. regani JF290460 Reg.06 Rio Mogi Guaçu, Brazil
H. ternetzi JF290462 YC-164 Antequera (27°27'43.43" S-58°52'0.03" W)
H. ternetzi JF290463 AG09-160 Yahapé (27º22'12.1"S-57º39'14.6"W)
H. uruguayensis JF290464 AG09-159 Yahapé (27º22'12.1"S-57º39'14.6"W)
H. uruguayensis JF290465 14731 P. N. Pre-Delta (32º07'18.0"S- 60º40'12.0"W)
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Sequence alignment, phylogenetic reconstruction, and molecular clock calibration
The mitochondrial D-loop sequences were obtained for 36 individuals from Argentina (for more details see Fig.1
and Table I). We also used sequences of different species of Hypostomus deposited in GenBank and nine others
species of the family Loricariidae as outgroups, as in Montoya-Burgos (2003). The editing of the new sequences
and the alignment were performed using BioEdit 7.0.1 (Hall, 1999). Prior to phylogenetic reconstruction,
appropriate substitution models were estimated with the Akaike information criterion (AIC) as implemented in
MrAIC (Nylander, 2004). We us ed a total o f 7 4 sequences o f Hypostomus to reconstruct the phylogeny. Two
phylogenetic reconstruction methods were used. First, maximum likelihood (ML) phylogenetic reconstruction was
performed using TreeFinder (Jobb et al., 2004). Confidence values for the edges of the ML tree were computed by
bootstrapping (Felsenstein, 1985), with 1000 replications. Second, Bayesian Inference analysis (BI) was conducted
using MrBayes 3.1.2 (Huelsenbeck and Ronquist, 2001; Ronquist and Huelsenbeck, 2003). Four chains were run
simultaneously (three heated, one cold) for 20,000,000 generations, with tree space sampled every 100th
generation. After a graphical analysis of the evolution of the likelihood scores, the first 300, 000 generations were
discarded as burn-in. The remaining trees were used to calculate the final consensus tree.
FIGURE 1. Map showing the sampling localities. The abbreviations mean: DE (arroyo Deseado, Iguazú river, Misiones); UR
(arroyo Uruzú, Paraná river, Misiones); GA (arroyo Garupá, Paraná river, Misiones); TA (arroyo Tabay, Paraná river,
Misiones); CA (Candelaria, Paraná river, Misiones); IT (Ituzaingó, Paraná river, Corrientes); YA (Yahapé, Paraná river,
Corrientes); CO (Corrientes river, Corrientes); AN (Antequera, Paraná river, Chaco); SU (Suquia river, Cordoba); MA
(Manucho river, Paraná river, Santa Fé); SF (Paraná river, Santa Fé); PN (Parque Nacional Pre-Delta, Paraná river, Entre Ríos);
EN (Ensenada, Río de La Plata, Buenos Aires); EP (arroyo El Pescado, Río de la Plata, Buenos Aires) and BO (lago del Paseo
del Bosque, La Plata).
Additionally, we performed molecular clock tests with HyPhy (Kosakovsky Pond et al., 2005) using the HKY85
model. The null hypothesis of constant molecular clock was tested for the ingroup taxa using the log likelihood ratio
test (Huelsenbeck and Crandall, 1997). Prior to these analyses, the data set was pruned to include only one
representative of each species. In addition, the sequence corresponding to H. fonchii and H. sp. Tib1 used in
Montoya-Burgos (2003) – were discarded because it showed a particularly long branch in the phylogenetic tree.
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ORIGIN OF SPECIES DIVERSITY IN HYPOSTOMUS.
TAB LE II. Morphometric data and counts of holotype and 23 paratypes of Hypostomus arecuta n. sp.
In order to evaluate the temporal diversification of species in the genus Hypostomus in the Paraná river basin,
the rate of evolution of the D-loop region needed to be calibrated. To do so, we used the same calibration point as
in Montoya-Burgos (2003), which is based on the following reasoning: the phylogeny of Hypostomus shows that
H. hondae, distributed only in the Lago Maracaibo and Magdalena basins, is the closest relative to H.
plecostomoides, which is known only from the Orinoco basin and some localities of upper Amazon. Because these
distribution patterns match the vicariant episode that separated Lago Maracaibo system from Amazon and Orinoco
basins 8 Ma (Hoorn, 1993), it is reasonable to attribute this age to the speciation event that gave rise to H. hondae
and H. plecostomoides. This geological event has also been used for calibrating other Neotropical fish phylogenies
(e.g. Lovejoy et al., 2000, Sivasundar et al., 2001).
Holotype range Mean / SD
Standard length (mm) 185.5 127.0–268.1
Percents of SL
Predorsal length 38.6 37.4–44.0 39.1 ± 1.57
Head length 32.1 29.5–34.4 31.3 ± 1.32
Cleithral width 32.3 29.2–32.7 30.9 ± 0.89
Head depth 19.5 17.2–19.9 18.9 ± 0.70
Dorsal-fin spine length 33.1 26.8–34.5 31.6 ± 2.28
Dorsal-fin base length 27.2 25.1–30.0 27.2 ± 1.20
Dorsal-adipose distance 16.3 15.1–16.9 16.1 ± 0.48
Thoracic length 24.0 19.8–26.2 23.3 ± 1.56
Pectoral-fin spine length 33.4 29.7–35.6 32.0 ± 1.23
Abdominal length 25.6 22.1–25.6 23.9 ± 0.84
Pelvic-fin spine length 24.9 22.3–25.8 24.1 ± 0.95
Caudal-peduncle length 27.4 27.4–33.3 30.6 ± 1.52
Caudal-peduncle depth 11.7 10.4–12.0 11.3 ± 0.45
Adipose-fin spine length 10.3 8.0–10.9 9.6 ± 0.86
Anal width 12.6 10.0–13.5 11.7 ± 0.79
Upper caudal-fin ray length 33.0 27.4–35.3 30.7 ± 2.06
Lower caudal-fin ray length 36.2 28.1–36.3 31.9 ± 2.44
Percents of head length
Head depth 60.8 57.7–63.6 60.7 ± 1.91
Snout length 61.3 61.2–66.8 63.0 ± 1.75
Orbital diameter 18.9 16.0–19.0 18.1 ± 0.94
Interorbital with 38.4 33.6–38.9 37.3 ± 1.47
Maxillary barbel length 12.2 9.3–15.2 12.1 ± 1.66
Mandibulary ramus length 24.5 21.7–25.4 23.3 ± 1.23
Counts mode
Median plates series 27/27 26/28 27
Predorsal plates 3 3–3 3
Dorsal plates below dorsal-fin base 9 9–10 9
Plates between dorsal and adipose fin 6 5–6 6
Plates between adipose and caudal fin 4 4–5 5
Plates between anal and caudal fin 14 12–14 14
Premaxillary teeth 74/79 66–85 77
Dentary teeth 71/72 63–84 80
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FIGURE 2. Maximum likelihood Hypostomus phylogenetic tree based on D-loop haplotypes (-lnL = 5192.34998). The ML tree
was derived using the HKY + G model of sequence evolution. Numbers next to branches are Bayesian posterior probabilities
followed by bootstrap values when these are above 50%, respectively. These support values are showed only for the relevant
relationships of this work. Bold letters are abbreviations used for naming clades (see text). The specimens from Paraná river
basin and Amazon system (Amazon basin, French Guyana and Northeastern South America coastal rivers) are indicated. The
three species marked with * inhabit the Paraná and Uruguay rivers, but not on the Río de La Plata. Also, we show the estimated
ages of dispersal events between basins (black arrow) and for vicariance events inside the La Plata basin (white arrow).
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ORIGIN OF SPECIES DIVERSITY IN HYPOSTOMUS.
Results
Phylogenetic analyses
A molecular phylogenetic approach was used to investigate the diversity of Hypostomus species from the Paraná
river basin. The sequence alignment comprised 592 positions, from which 179 were variable within the ingroup.
Base composition and structural characteristics of Hypostomus D-loop sequences are described elsewhere
(Montoya-Burgos et al., 2002). The model of sequence evolution that fit the best our sequence data set is HKY +
gamma, according to MrAIC (Nylander, 2004). The ML and Bayesian phylogenetic trees obtained have similar
topologies. The ML tree is shown in Fig. 2.
The evolutionary relationships of the outgroup species is the same as found in Montoya-Burgos (2003). All
Hypostomus species form a monophyletic clade named Clade D (Fig. 2). This clade can be organized into four
monophyletic groups, D1, D2, D3, and D4. Clade D1 clusters together with D2 and Clade D3 with D4. The
relationships among these clades are supported by high Bayesian posterior probabilities but relatively low
bootstrap values. Hypostomus gymnorhynchus is placed as the sister species to clades D1 and D2 and thus forms a
distinct monospecific lineage. The Clade D1 (Fig. 2) forms the H. cochliodon group including H. cochliodon from
the Paraná river basin, H. plecostomoides from Orinoco basin, H. hondae from Lago Maracaibo and Magdalena
basins, H. fonchii and Hypostomus sp. 1013 from the Amazon basin (see Montoya-Burgos (2003) for the non
described species metioned in this work).
Clade D2 is subdivided into two monophyletic groups: the first contains species from French Guyana (H.
watwata and H. plecostomus), Amazon basin (represented with Hypostomus spp.: 36, 49), and Northeastern South
America coastal rivers (Hypostomus spp.: 177, 219, and 270 from Gurupí, Itapicurú, and Parnaíba rivers,
respectively). The second clade includes species from Eastern South America coastal rivers (H. puntactus from
Ubatiba), and the La Plata basin (H. commersoni, H. derbyi, H. paranensis, H. boulengeri, and two Hypostomus
spp.: Tib13 and. 1211).
Clade D3 is also subdivided into two groups, one clade including species from the Amazon basin (H. asperatus
and three Hypostomus spp.: 906, 1100, and 1026). The other clade contains species from La Plata basin and São
Francisco river (H. regani; H. luteomaculatus; H. microstomus; H. myersi, H. nigromaculatus, and three
Hypostomus spp.: 678, 699, and 751).
Finally, clade D4 includes species inhabiting the La Plata basin: Hypostomus arecuta n. sp. (described below),
H. ternetzi, H. uruguayensis, H. aspilogaster, H. luteus, H. isbrueckeri, H. latifrons, H. latirostris, and H.
albopunctactus. This clade comprises also H. luetkeni from Eastern South America coastal rivers (Paraíba river)
and H. johnii from an northeastern South America coastal river (Parnaíba river).
Our results show that at least one species inhabiting Paraná river basin is present in each of the four main
Hypostomus clades (i.e. H. cochliodon in clade D1; H. commersoni, H. derbyi, H. paranensis, and Hypostomus
spp: Tib13 and 1211 in clade D2; H. luteomaculatus; H. microstomus, H. myersi, H. regani, H. nigromaculatus, and
H. sp 699 in clade D3; finally, the new species Hypostomus arecuta n. sp., H. ternetzi, H. uruguayensis, and H.
albopunctatus in clade D4).
Phylogenetic tree calibration.
When analysing the ingroup taxa, with the exclusion of H. fonchi which has a particularly long terminal branch
(clade D in Fig. 2), the log-likelihood ratio test of homogeneous evolutionary rate showed no significant
differences between the likelihood scores obtained when enforcing or not the molecular clock (X2 = 56.03; d.f. =
43; P = 0.087). This result indicates that the sequences of the ingroup representatives are evolving at a
homogeneous rate. With the aim of evaluate the temporal diversification of the genus Hypostomus in the Paraná
river basin, we calibrated the D-loop region. We found that the splitting between the Hypostomus from the Amazon
system (comprising the Amazon basin, French Guyana and North-eastern South America coastal rivers) and La
Plata basin is estimated to 6.5 Ma in clade D1, 11.3 Ma in clade D2, 11.8 Ma in clade D3 and 9.3 Ma in clade D4.
Moreover, the origin of temporal diversification among the lineages inhabiting the La Plata basin is dated to 7.45
Ma in clade D2, 9.35 Ma in clade D3 and 13.5 Ma in clade D4.
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FIGURE 3. Hypostomus arecuta n. sp., Holotype. MACN-ict 9677 (198), 185.5 mm SL. Dorsal, lateral, and ventral views.
Photos by Yamila P. Cardoso.
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ORIGIN OF SPECIES DIVERSITY IN HYPOSTOMUS.
Hypostomus arecuta n. sp.
Fig. 3.
Here, we describe a new species that inhabit the Paraná river basin and which contributes to the understanding of
the origin of the species diversity in this basin (see discussion).
Holotype: MACN-Ict 9677 (198), 185.5 mm SL, Argentina, Corrientes province, Ituzaingó, Paraná River
(27°29’54.5''S - 56°42’47.0''W). Col: Gonzalez et al., November, 2009.
Paratypes: MACN-ict 9678 (163, 166), 2 ex., 174.0–243.3 mm SL, Argentina, Corrientes province, Yahapé,
Paraná river, (27°22’12.1''S-57°39’14.6''W). Col: Gonzalez et al., November, 2009. MACN-ict 9679 (181, 191,
192, 193, 195, 196, 197, 199), 9 ex., 156.5–268.1 mm SL, same data as holotype. MACN-ict 9680 (CIA 284–285),
2 ex., 127.0–134.7 mm SL, Argentina, Misiones province, Candelaria city, Paraná river (27º26’92’’S-
55º44’50’’W). Col: Aichino and Capli , November, 2009.
Diagnosis
Hypostomus arecuta n. sp. is distinguished from its congeners by the following combination of characters:
dorsum of head and body and all fins dark grey covered by numerous rounded cream dots. Ventral surface of head
and belly a plain cream color. This color pattern distinguishes H. arecuta n. sp. from Hypostomus species that have
dark roundish dots on a lighter background (such: H. ancistroides, H. brevis, H. commersoni, H. fluviatilis, H.
hermanni, H. iheringii, H. nigromaculatus, H. paulinus, H. topavae, H. isbruekeri, H. aspilogaster, H.
uruguayensis, H. latifrons, and H. latirostris). Among the species that have light roundish dots or irregular light
marks on a darker background, H. arecuta n. sp. is distinguished by number of premaxillary/dentary teeth (66–85/
63–84) as compared to H. albopuctatus (26–32/22–26), H. luteus (22–38/26–40), H. regani (63–107/63–104), H.
luetkeni (30–69/38–68), H. strigaticeps (about 60), H. multidens (115–260/122–267) and H. microstomus (7–11/7–
13). Hypostomus arecuta n. sp. is distinguished from its sister species H. ternetzi by the colour pattern of dorsum of
head and body, and all fins dark grey covered by numerous rounded cream dots vs. dorsum homogeneously dark,
and greater number of scutes at dorsal-fin base (9–10 vs. 8). Also, some morphometric characters differentiate H.
arecuta n. sp. from H. ternetzi: cleithral width (3.0–3.4 vs. 2.8–2.9 in SL), abdominal length (3.9–4.5 vs. 4.6–5.4 in
SL), eye diameter (5.2–6.2 vs. 6.2–6.9 in HL), pelvic fin-spine length (3.9–4.5 vs. 3.1–3.8 in SL), caudal penduncle
depth (8.3–9.6 vs. 7.5–8.1 in SL), upper caudal-ray length (2.83.6 vs. 2.0–2.3 in SL), lower caudal-ray length
(2.4–3.5 vs. 1.8–2.0 in SL), and right mandibular ramus (3.9–4.6 vs. 4.8–5.6 in HL). Besides, H. arecuta n. sp.
differs from H. luteus by short dorsal spine length (mean 31.6 % vs. 34.4 % of SL), the length of right mandibular
ramus (3.9–4.6 vs. 4.8–6.1 in HL), abdominal length (3.9–4.5 vs. 4.4–5.0 in SL), head depth (1.6–1.7 vs. 1.7–1.9 in
HL), and interorbital width (2.6–3.0 vs. 2.9–3.6 in HL). Also some ratios distinguish H. arecuta n. sp. from H.
luetkeni: predorsal length (2.3–2.6 vs. 2.5–3.0 in SL), cleithral width (3.0–3.4 vs. 3.3–4.0 in SL), pectoral-fin spine
length (2.8–3.3 vs. 3.1–3.8 in SL), and caudal peduncle length (3.0–3.6 vs. 2.8–3.1). Finally, short dorsal spine
length separates H. arecuta n. sp. from H. luteomaculatus (mean 31.6 % vs. 40% of SL).
Hypostomus arecuta can be differentiated from H. boulengeri, H. commersoni and H. cochliodon by the colour
pattern. Also, H. commersoni has strong lateral keels which are absent in H. arecuta, H. cohliodon bears fewer
premaxillary and dentary teeth than H. arecuta n. sp (8/9 vs. 66–85/63–84, respectively). Hypostomus arecuta
shares with H. luetomaculatus and H. microstomus a similar dorsal colour pattern, however H. luteomaculatus and
H. microstomus have dark ventral surface of head and body with light vermiculated dots vs. head and belly plain
cream in H. arecuta. Some counts distinguish H. arecuta from H. luteomaculatus: scutes along lateral line 26–28
(mode 27) vs 28–29 (mode 29), scutes between end of dorsal fin to adipose fin 5–6 (mode 6) vs 6–7 (mode 7);
scutes from adipose to caudal fins 3–5 (mode 5) vs. 5–8 (mode 6), and scutes from anal to caudal fins 12–14 (mode
14) vs. 14–16 (mode 16), respectively. Finally H. arecuta n. sp. has a greater number of teeth than H. microstomus
(66–85/63–84 vs. 7–11/7–13).
Description
Meristic and morphometric data are presented in Table I. Dorsal profile slightly convex from snout tip to
anterior margin of eyes, straight at interorbital area, convex from interorbital area to dorsal-fin origin, and almost
straight from dorsal-fin origin to end of adipose fin. Body width at cleithral region larger than head depth. Head
broad and shallow dorsally covered with plates, except for a quadrangular naked area on snout tip.
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Supraoccipital bone with a shallow median ridge, and with a relatively well developed posterior process
bordered by a wide nuchal plate. A shallow ridge originating laterally to the nares, passing through supraorbital,
and extending to median portion of pterotic-supracleithrum. Opercle small, with odontodes more developed
distally.
Oral disk ovoid, lower lip covered with numerous papillae decreasing in size posteriorly. Maxillary barbels
moderately developed, about as long as orbital diameter. Sixty-six to 85 (holotype 74) teeth in premaxilla, 63 to 84
(holotype 72) in dentary. Teeth bicuspid, curved inward distally, mesial cusp two or three times longer than lateral
cusp, distal margin of mesial cusp rounded in replacement teeth and straight in functional ones. Body covered with
five rows of moderately spinulose scutes. Tip of snout mostly naked even in large specimens, bearing two lateral
vertical patches of odontodes.
Ve nt r a l s u rf a ce o f h e ad n a ke d , w i th s m al l o r l ar g e p a tc h o f p l at e l et s b e fo r e b r an c h ia l o p en i ng . A bd o me n
covered with minute platelets, with exception of small area around pectoral fin and small or large area around
pelvic-fin insertions, and small area at urogenital opening. Preanal plate absent. Caudal peduncle laterally
compressed, rather ovoid in cross section.
Twe nty-one to 23 (mode 22) dors al plate s, 25–2 6 (mod e 24) mid-d ors al pla tes , 24– 25 (mo de 25) median
plates, 26–28 (mode 27) mid-ventral plates, 21–22 (mode 22) ventral plates. Three predorsal plates, 9–10 (mode 9)
plates below dorsal fin, 5–6 (mode 6) preadipose plates, 4–5 (mode 5) plates between adipose fin and caudal fin,
12–14 (mode 14) plates between anal fin and caudal fin.
Dorsal-fin II,7, its origin placed at vertical closer to pelvic-fin origin than pectoral-fin origin. Dorsal-fin
margin straight. Adipose-fin spine compressed and curved backward. Pectoral fin I,6, its posterior border straight.
Pectoral-fin spine slightly curved inward, covered with weakly developed odontodes, slightly more developed on
its distal portion in larger specimens. Tip of pectoral fin reaching one-third pelvic-fin spine length. Pelvic-fin I,5,
its posterior border slightly roundish. Pelvic-fin spine surpassing anal-fin origin. Anal fin I,4, its tip reaching the
6th plate after its origin, 2ed and 3rd branched rays longer. Caudal-fin margin concave, I,14,I, with inferior lobe
longer than superior one.
Phylogenetic position of Hypostomus arecuta
The new species described above, Hypostomus arecuta, is distinguished from others species of the genus by a
combination of morphological and molecular features. Hypostomus arecuta is apparently endemic to the Paraná
river in Argentina. According to our phylogenetic tree, H. arecuta, together with H. ternetzi, H. isbruekeri, H.
aspilogaster, H. uruguayensis, H. latifrons, H. latirostris, H. luteus, H. albopuntactus, H. johnii and H. luetkeni
form the clade D4 (see Fig. 2). Although our results show that the node that clusters clades D4 and D3 shows low
statistical support in the ML analysis, other data support this relationship: following Muller and Weber (1992), the
Hypostomus species of clade D4 shares with species of clade D3 the presence of white spots on the body, wide
mandible, and long-crowned teeth (defining the so called Hypostomus regani group). Species belonging to other
clades (D1 and D2, Fig. 2) display black widespread spots on the body, medium-sized mandible, and short-
crowned teeth (forming the so called Hypostomus plecostomus group). Moreover, karyological studies show that
some species of the Hypostomus regani group have a fundamental chromosome number of near 72 and some
species of the Hypostomus plecostomus group have a fundamental number near 68 (Zawadzki et al., 2004).
Therefore, these morphological, colour pattern and karyological data support our phylogenetic analyses showing a
division of Hypostomus species into two principal clades, clade D1+D2 (Hypostomus plecostomus group) and
clade D3+D4 (Hypostomus regani group). Thus, the new species H. arecuta. is considered as a member of the
Hypostomus regani group.
Colour in alcohol
Overall ground colour of body and fins dark grey. Overall ground color of ventral area a plain, lighter, cream
color in some specimens. Dorsal surface of head, body, and fins entirely covered by numerous rounded cream dots,
smaller and closer on head. Dorsal, pectoral, and pelvic- fins with dots regularly or irregularly arranged in rows
along their rays. Adipose fin with rounded, cream dots. Caudal fin with scattered, rounded cream dots on rays and
membranes.
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ORIGIN OF SPECIES DIVERSITY IN HYPOSTOMUS.
Distribution
Hypostomus arecuta is known from the Paraná river at Yahapé and Ituzaingó (Corrientes province), Candelaria
(Misiones province), and Santa Fé (Santa Fé province), Argentina. Hypostomus arecuta is sympatric with H.
commersoni, H. cochliodon, H. uruguayensis, H. latifrons, H. ternetzi, H. luteomaculatus, H. microstomus, and H.
boulengeri.
Etymology
The specific epithet arecuta is a Guaraní word arecutá that means loricariid fish.
Habitat
The specimens of Hypostomus arecuta were collected in coastal areas of the Paraná river main channel. The
bottom was composed mostly by large boulders of sandstone with patches of sand and pebbles. The species was
found in well oxygenated waters having moderate current speed, about 0.60 m s-1. Water transparency was within
the most frequent range registered in the river (1.50–2.40 m). Conductivity was generally low and typical for the
river (50.9–59.6 µS cm-1). The pH was slightly acidic to neutral (6.8–7.1).
Discussion
The origin of species diversity of Hypostomus in the Paraná river basin
According to the results presented here and to Montoya-Burgos (2002, 2003), the phylogenetic tree of the
genus Hypostomus can be divided into four principal clades (Fig. 2). Since each clade includes at least one species
from the Paraná river basin and at least one from the large Amazon system, it can be deduced that old inter-basin
allopatric speciation has participated in the diversification of Hypostomus in the Paraná river basin. In addition,
lineages with multiple species inhabiting the Paraná river basin are found in clades D2, D3 and D4. This indicates
that speciation within the basin also shaped the diversity of Hypostomus there.
The biogeographic analysis of the inter-basin relationships in clade D1 shows that H. cochliodon, from the
Paraná river, clusters with Hypostomus sp. 1013, from the Amazon basin (Fig. 2), and our calibrations indicate that
the splitting event can be dated to 6.5 Ma. To explain this age, we would have to invoke temporal connections
between the upper Paraguay and Southern tributaries of the Amazon posterior to the inferred age of the boundary
displacements and water interchange between the Northern paleo Amazon-Orinoco basin and La Plata basin (11.8–
10 Ma) (Lundberg et al., 1998). When these temporal interconnections ceased, the isolation of populations in both
basins would have resulted in the allopatric speciation that gave rise to H. cochliodon and H. sp. 1013.
The clade D2 shows that species inhabiting the Amazon system cluster with species from La Plata basin +
Eastern South America coastal rivers (Fig. 2). According to the D-loop molecular clock, the splitting event between
these two groups can be dated to 11.3 Ma. This result is in accordance with the estimated date for this clade in
Montoya-Burgos (2003). This inferred age matches with the documented boundary displacements between the
Northern paleo Amazon-Orinoco system and the La Plata basin that occurred at about 11.8–10 Ma (Lundberg et al.,
1998). Once the headwater exchanges due to the boundary displacement were finished, the isolation of populations
in both basins would have resulted in speciation, giving rise to the two lineages of clade D2.
Within clade D3, the species inhabiting the Amazon basin and those from La Plata basin + São Francisco river
(see Fig.2) form two distinct lineages that originated about 11.8 Ma according to the D-loop data. In Montoya-
Burgos (2003), this event had a slightly more recent date (10.2–10.1 Ma.). However, both estimations correspond
well with the date estimated for the last major water interchange between the paleo Amazon-Orinoco and La Plata
basin reported above for clade D2.
In clade D4, the splitting between species inhabiting North-eastern South America coastal rivers (being part of
the Amazon system), represented by H. johnii, and species from the Paraná river + Eastern South America coastal
rivers, represented by H. albopunctatus + H. luetkeni, was dated to 9.3 Ma. Differing from what was proposed in
Montoya-Burgos (2003), this estimated age does not correspond to the boundary displacements between the
Northern paleo Amazon-Orinoco system and La Plata basin (11.8–10 Ma). This difference can be explained by the
exclusion of the sequence of Hypostomus sp. (Tib 1), used in Montoya-Burgos (2003), from our analysis and also
because in this work we used a smaller segment of D-loop marker than in Montoya-Burgos (2003). According to
our results, the diversification episode within clade D4 would be another case of more recent water interchange via
a temporal connection between the two main basins, as was already the case for clade D1. In addition, the
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evolutionary position of H. johnii within the clade D4 (fig. 2) would allow us to suggest that the direction of the
dispersal event was from the La Plata basin towards the Amazon system.
In summary, our results suggest that at least four independent allopatric speciation episodes occurred between
the Amazon system and the Paraná basin river + São Francisco + Eastern South America coastal rivers. In clade D2
and D3, these allopatric speciations may be explained by the boundary displacement between the Northern paleo
Amazon–Orinoco and the Southern La Plata basin which occurred between 11.8–10 Ma (Lundberg et al., 1998).
As indicated in clades D1 and D4, two more recent allopatric speciations (6.5 Ma for clade D1 and 9.3 Ma for clade
D4) occurred by headwater exchanges and subsequent isolation between the northern and southern river systems,
involving probably the upper Paraguay and Southern tributaries of the Amazon (Lundberg et al., 1998).
Accordingly, more recent population splitting between the Amazon and Paraná river basins has been reported
(between 2.3 and 4.1 Ma) for the migratory fish Prochilodus (Sivasundar et al., 2001). Moreover, other recent
dispersal events between these two basins are further exemplified by the distribution ranges of Pygocentrus
nattereri (Hubert et al., 2007) and Pseudotylosurus augusticeps (Lovejoy and De Araújo, 2000). These data and
our results suggest that the temporary connections between the Amazon and Paraná river basins would be more
frequent than previously thought.
The second origin of the diversity of Hypostomus species in the Para river basin is shaped by intra-basin
speciation and occurs within the La Plata basin. In clade D2, the node including all species present in La Plata basin
(seven species) was estimated to 7.45 Ma according to our molecular clock. This date coincides with the second
reported event of maximum flooding of marine transgression during the Miocene (10-5 Ma) (Hernández et al.,
2005). The extensive marine incursion onto the Paraná river basin could have isolated the tributaries of this basin,
generating several allopatric speciations in different and strictly freshwater organisms that habited the La Plata
basin. Once the sea retreated, the newly formed species would have dispersed throughout the current La Plata
basin, enriching its biodiversity. It is important to note that H. puntactus from Eastern South American coastal
rivers emerges within the group inhabiting the La Plata basin. This fact was explained by Montoya-Burgos (2003)
as a dispersal event from the La Plata basin towards the Eastern South American coastal rivers.
In clade D3, the calculated age for the origin of the species occupying the La Plata basin is 9.35 Ma. (eight
species). This estimated age also coincides with the event of the marine transgression that occurred 10-5 Ma
(Hernández et al., 2005). Also, within this clade, there are species of the São Francisco river, which reveal,
according to Montoya-Burgos (2003), a colonization event of the São Francisco river from the La Plata basin.
In clade D4, the node that contains the species inhabiting the La Plata basin is dated to 13.5 Ma; since then at
least 10 species were formed. This estimated age is in accordance with the first event of maximum flooding of the
marine transgression that occurred 15-13 Ma (Hernández et al., 2005). As previously mentioned, within this clade
emerges H. johnii from Northern South America coastal rivers and H. luetkeni from Eastern South America coastal
rivers. This result demonstrates two dispersal events; both are posterior to the origin of the species diversity of the
La Plata basin.
It is important to note that intra-basin diversification increases with the age of the origin of the lineage. In clade
D2 the intra-basin diversification started 7.45 Ma and generated seven species; in clade D3 it started 9.35 Ma and
gave rise to eight species; in clade D4 it started 13.5 Ma and resulted in ten species. These species numbers are
underestimates as new species might be discovered and others might have become extinct. In this respect, the new
species described here, H. arecuta, contributes importantly to our understanding that clade D4 is the most ancient
and diverse Hypostomus lineage inhabiting almost exclusively the La Plata basin. This high diversity is the result
of intra-basin speciations.
Therefore, we see that Hypostomus species diversity in the Paraná river, and in consequence in the La Plata
basin, is moulded by two processes. One is the inter-basin diversification, which generated groups of species
inhabiting different basins as result of dispersal events, as proposed by the hydrogeological hypothesis (Montoya-
Burgos, 2003). In this context, paleo hydrogeological changes during the Miocene have promoted vicariance and
dispersal routes yielding a high degree of diversification of species of fishes in the Neotropical region. The other
process that shaped species diversity of Hypostomus is intra-basin speciation, which produced groups of species
inside a basin due to habitat fragmentation. We see that the origin of species diversity inside the La Plata basin
temporally matches with the marine transgression in the Paraná river basin. As proposed by the museum hypothesis
(Nores, 1999), this marine incursion could have fragmented the La Plata basin resulting in several allopatric
speciation events. The historical biogeography of Hypostomus argues that several documented hydrological and
sea level changes deeply influenced the cladogenetic events observed in the phylogeny of this genus.
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ORIGIN OF SPECIES DIVERSITY IN HYPOSTOMUS.
Possible connection between the Paraná and Uruguay rivers
The hydrographical patterns of the Paraná and Uruguay rivers indicate that they can be considered as
belonging to the same basin (La Plata basin) as the Lower Paraná is connected to the Lower Uruguay via the Río de
la Plata estuary. This configuration has been maintained almost unchanged for the last 10 Ma (Lundberg et al.,
1998). Sivasundar et al. (2001) mentioned that several conspecific populations are currently distributed along the
Paraná and Uruguay rivers, dispersing probably through the Río de la Plata estuary. This dispersal route, which
allows gene flow between the two rivers, may explain why representatives of H. commersoni are genetically
similar in those two rivers as well as in the Río de la Plata estuary. However, according to the distribution range of
some Hypostomus species in the La Plata basin, we can propose other possible ancient dispersal routes between the
Paraná and Uruguay rivers. The examined material in this work and the bibliography about Hypostomus
luteomaculatus, H. uruguayensis, and H. ternetzi show that these species are distributed in the Paraná and Uruguay
rivers. Contrary to H. commersoni, these species have never been reported from the Río de la Plata estuary. These
three species could have either gone extinct or have left the Río de la Plata estuary. Alternatively, they might have
dispersed through temporal connections between Northern tributaries of the Paraná and Uruguay rivers.
During the Miocene (24-5 Ma), the Paraná and Uruguay rivers became disconnected from one another
resulting in the present configuration (Beurlen, 1970). However, the topology and proximity between some
tributaries of these two rivers allows us to hypothesize that water pathways between the Paraná and Uruguay rivers
could have existed during flood periods. Weber (1987) suggested that the Aguapey river can be a connection
between the Paraná and Uruguay rivers. Later on, Casciotta et al. (2005) mentioned that it is probable that at
present ichthyofaunal exchanges can take place between the Laguna Iberá (Paraná river basin) and the Miriñay
river (Uruguay river basin) during flood periods. An exhaustive population genetic analysis could be useful to
understand the dispersal routes used by some Hypostomus species to maintain gene flow between populations
inhabiting Paraná and Uruguay rivers basin.
Acknowledgements
We ar e grateful to F. Br ancolini, E. Ru eda, A. Pa racampo, F. Vargas, and members of the INICNE (UNNE) for
helping us in the field trips and in the sampling process. We thank R. Corvain and S. Fisch-Muller (MHNG) for
sharing samples with us. We thank Convenio IBOL-CONICET Argentina, CONICET, and Comisión de
Investigaciones Científicas de la Provincia de Buenos Aires, Claraz Foundation, and the Canton de Genève for
their financial support for field trips and laboratory equipment. We also thank the PUCRS for sharing with us
specimens of H. luteomaculatus and H. luteus, and James Maclaine of NHM for the images of syntypes of H.
strigaticeps. Wa are grateful to M. Rodrigues de Carvalho and two anonymous reviewers for their valuable
comments and suggestions.
Additional specimens examined
Argentina. Hypostomus boulengeri, MACN-ict 9644, 1 ex., 121.8 mm, Corrientes Province, Paraná river at
Ituzaingó. Hypostomus commersoni: ILPLA1907, 8ex, El Pescado, La Plata, Buenos Aires. Hypostomus
paranensis: ILPLA1914, 2 ex, Córdoba, Córdoba Capital, Suquia river. Hypostomus ternetzi, MACN-ict 9645, 1
ex. 150 mm Corrientes Province, Paraná river at Yahape. Hypostomus uruguayensis, MACN-ict 9651, 1 ex., 159.0
mm, Corrientes Province, Paraná river at Yahape. Brazil. Hypostomus luteus: MCP19991, 1ex., Santa Catalina,
Uruguay river basin, Uruguai river, proximo a pedra da Fortaleza. MCP20751, 1ex., Santa Catalina, Uruguay river
basin, Uruguai river, proximo a pedra da Fortaleza. Hypostomus regani: MCP19989, 1 ex., Santa Catalina,
Uruguay river basin, Uruguai river, proximo a pedra da Fortaleza. MCP28628, 1 ex., Rio Grande do Sul, Uruguay
river basin, Uruguai river, no Remanso da Timbaúva, cerca de 1500m do início do Salto do Yucuma. MHNG
2547.017, 3ex. , 141, 86–162,09 mm, Sao Pablo, Mogui Guazu Cach.
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... This wide distribution is the result of outstanding continental radiation experienced throughout Hypostomus evolutionary history [99,151]. In South America, several species have their occurrence registered in the tributaries of the Paraná, Paraguay, Uruguay, and Amazonas basins, representing, therefore, a significant component of the neotropical freshwater ichthyofauna [32,88]. ...
... These species have economic potential and are intensely fished in their regions of occurrence [108]. Ecologically, species of the genus Hypostomus have shown to be a very interesting model for understanding the role played by hydrogeological history in shaping fish diversity and distribution in South America [32,99] as well as to explore the nature of continental fish radiations in the Tropics [151]. ...
... These characteristics have made it challenging to delimit species on a morphological basis throughout the long and rich history of Hypostomus descriptions. Therefore, several papers are reviewing and discussing the taxonomic structures of the group [13, 23,32,45,77,79,94,111,120,127,130,185]. For this reason, we restrict this review to the classes of markers and studies that are not based only on morphological data. ...
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This review compiles and discusses the use of genetic markers applied in the study of the fish genus Hypostomus Lacépède, 1803 (Siluriformes: Loricariidae). The database comprises 51 peer-review articles that were published in the last 52 years (1968–2020) and that approach analysis based on different classes of genetic markers. The use of cytogenetic and enzymatic markers was predominantly especially in population studies with the genus Hypostomus, while mitochondrial markers were the majority in phylogenetic studies. Although significant methodological advances have occurred for molecular evaluation, they are still modestly applied to the study of neotropical fish genera, in which Hypostomus is included. New perspectives, especially on integrative approaches, are needed to improve our knowledge of the genetic functionality of fishes.
... Both maximum likelihood tree (ML) and Bayesian Inference (BI) retrieved the same topology, with well-supported clades [> 70 bootstraping (BS) and > 0.9 posterior probability (PP)]. Our results supported the organization of Hypostomus into four groups, named D1, D2, D3 and D4 (all of them with BS = 100 and PP = 1), as initially proposed by Montoya-Burgos 3 , retrieved by Cardoso et al. [14][15][16] and recently by Jardim de Queiroz et al. 43 . However, our analyses showed a different relationship among these clades (D1(D2(D3 + D4))) with high BS and PP values. ...
... Our robust Hypostomus phylogeny provides the opportunity to investigate the processes of evolutionary diversification in one of the most species-rich Neotropical fish genera. A graphic summary of the main colonizations in the evolutionary history of the genus Hypostomus in La Plata Basin is shown in Fig. 4. Previous studies included fewer taxa or were based on fewer molecular markers, resulting in trees with lower statistical support and/or with polytomies within the inter-species relationships 3,8,10,14 . Nevertheless, the main lineages within the genus are similar to those found in 3,10,[14][15][16]43 , where four main Clades D1, D2, D3, and D4 were identified. ...
... A graphic summary of the main colonizations in the evolutionary history of the genus Hypostomus in La Plata Basin is shown in Fig. 4. Previous studies included fewer taxa or were based on fewer molecular markers, resulting in trees with lower statistical support and/or with polytomies within the inter-species relationships 3,8,10,14 . Nevertheless, the main lineages within the genus are similar to those found in 3,10,[14][15][16]43 , where four main Clades D1, D2, D3, and D4 were identified. The South American fish fauna is the most diverse freshwater fish assemblage in the world and currently comprises more than 5000 described species, with many more still undescribed 69 . ...
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Distribution history of the widespread Neotropical genus Hypostomus to shed light on the processes that shaped species diversity. We inferred a calibrated phylogeny; ancestral habitat preference, ancestral areas distribution, and the history of dispersal and vicariance events of this genus. The phylogenetic and distributional analyses indicate that Hypostomus species inhabiting La Plata Basin do not form a monophyletic clade, suggesting that several unrelated ancestral species colonized this basin in the Miocene (∼17 Mya). Dispersal to other rivers of La Plata Basin started about 8 Mya, followed by habitat shifts and an increased rate of cladogenesis. Amazonian Hypostomus species colonized La Plata Basin several times in the Middle Miocene, probably via the Upper Paraná and the Paraguay rivers that acted as biogeographic corridors. During the Miocene, La Plata Basin experienced marine incursions; and geomorphological and climatic changes that reconfigured its drainage pattern, driving the dispersal and diversification of Hypostomus . The Miocene marine incursion was a strong barrier and its retraction triggered Hypostomus dispersal, increased speciation rate and ecological diversification. The timing of hydrogeological changes in La Plata Basin coincides well with Hypostomus cladogenetic events, indicating that the history of this basin has acted on the diversification of its biota.
... This characteristic has made challenging to properly delimit species on a morphological basis throughout the long and rich history of Hypostomus descriptions. Modern molecular phylogenetic methods have been very useful to solve taxonomic issues and unravel hidden diversity within Hypostomus (Cardoso et al., 2019(Cardoso et al., , 2016(Cardoso et al., , 2012(Cardoso et al., , 2011Montoya-Burgos, 2003;Weber and Montoya-Burgos, 2002). ...
... Hypostomus has been shown to be a very interesting model to unravel the role played by hydrogeological history in shaping fish diversity and distribution in South America (Cardoso et al., 2012;Montoya-Burgos, 2003) as well as the nature of continental fish radiations in the Tropics (Silva et al., 2016). However, these studies were based on a limited taxonomic sampling, especially with a few species from the wide Amazon Basin and Guianese rivers. ...
... (ii) Mitochondrial D-loop: we amplified a fragment of 620 bp of this hypervariable non-coding region. The D-loop shows an impressive accumulation of substitutions and indels (Brown et al., 1986;Saccone et al., 1987), which has been considered informative for phylogenetic studies in fish (Cardoso et al., 2016(Cardoso et al., , 2012Cardoso and Montoya-Burgos, 2009;Montoya-Burgos, 2003;Montoya-Burgos et al., 2002). (iii) Gene encoding Teneurin transmembrane protein 3: four genes of the teneurin group have been reported in vertebrates (Tucker and Chiquet-Ehrismann, 2006). ...
Article
With 149 currently recognized species, Hypostomus is one of the most species-rich catfish genera in the world, widely distributed over most of the Neotropical region. To clarify the evolutionary history of this genus, we reconstructed a comprehensive phylogeny of Hypostomus based on four nuclear and two mitochondrial markers. A total of 206 specimens collected from the main Neotropical rivers were included in the present study. Combining morphology and a Bayesian multispecies coalescent (MSC) approach, we recovered 85 previously recognized species plus 23 putative new species, organized into 118 ‘clusters’. We presented the Cluster Credibility (CC) index that provides numerical support for every hypothesis of cluster delimitation, facilitating delimitation decisions. We then examined the correspondence between the morphologically identified species and their inter-specific COI barcode pairwise divergence. The mean COI barcode divergence between morphological sisters species was 1.3 ± 1.2%, and only in 11% of the comparisons the divergence was 2%. This indicates that the COI barcode threshold of 2% classically used to delimit fish species would seriously underestimate the number of species in Hypostomus, advocating for a taxon-specific COI-based inter-specific divergence threshold to be used only when approximations of species richness are needed. The phylogeny of the 108 Hypostomus species, together with 35 additional outgroup species, confirms the monophyly of the genus. Four well-supported main lineages were retrieved,herein after called super-groups: Hypostomus cochliodon, H. hemiurus, H. auroguttatus, and H. plecostomus super-groups. We present a compilation of diagnostic characters for each supergroup. Our phylogeny lays the foundation for future studies on biogeography and on macroevolution to better understand the successful radiation of this Neotropical fish genus.
... The species are widely distributed in South America, from Costa Rica to the Salado River Basin in Argentina (Ringuelet 1975). Two recent studies show the phylogenetic relationships of several species of Hypostomus in the southern part of its distribution, which comprises the lower Paraná and the Río de la Plata Basin (Cardoso et al. 2012(Cardoso et al. , 2016. ...
... New sequences were deposited in genBank for: H. commersoni (JF290450 to JF290458, Mg457220 to Mg457223, Mg457234 to Mg457242), H. cordovae (KX852401 to KX852410), H. laplatae (KX852411 to KX852418), and H. spiniger (Mg457224 to Mg457233). Also, published data for Hypostomus (Montoya-Burgos 2003, Cardoso et al. 2012 were used, so some specimens were incorporated only in the molecular analyses (see Fig. 1). In total, 109 sequences were edited and manually aligned using Bioedit 7.0.1 (Hall 1999). ...
... The best-fit substitution model found for the dataset was gTR+I+g. evolutionary relationships within the genus (Fig. 2) were similar to those reported by Montoya-Burgos (2003) and Cardoso et al. (2012Cardoso et al. ( , 2016, with four main lineages: D1, D2, D3, and D4 (Fig. 2). However, in the analyses, the statistical support was generally low among species, generating polytomies in the BI tree due to the collapse of some branches supported by posterior probabilities < 0.5. ...
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Hypostomus commersoni Valenciennes 1836, Hypostomus cordovae (günther 1880) and Hypostomus laplatae (eigenmann 1907) have been little studied since their original descriptions. This study shows a comprehensive review of these species from the lower la Plata Basin, including their taxonomic history, distribution, color patterns, morphology, and ecological and molecular phylogenetic data. Morphological and phylogenetic analyses based on D-loop sequences suggested that H. commersoni can be separated into two subclades, or subgroups. Based on these results and on the non-overlapping distribution range of the two subclades, we conclude that they represent two distinct species, thereby revalidating H. spiniger. The results also suggest that H. paranensis should be considered as species inquirenda and H. cordovae as valid species. This integrated approach provides key information for assessing the conservation status and biogeographic aspects of the genus Hypostomus in the lower la Plata Basin.
... During the past years, several collecting trips were made to the upper Bermejo basin in northwestern Argentina, revealing the presence of at least 15 previously unrecorded or new species, such as Andromakhe latens (Mirande, Aguilera & Azpelicueta 2004), Hypostomus boulengeri (Eigenmann & Kennedy 1903) (in Alonso et al., 2016;Cardoso et al., 2016), Hypostomus cochliodon Kner 1854 (in Cardoso et al., 2012;Terán et al., 2016), H. ...
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Specimens of Imparfinis were recently collected in northwestern Argentina from the Bermejo River basin (Salta and Jujuy Provinces), del Valle River (Salta Province) and Horcones River (Santiago del Estero Province). An integrative approach to taxonomy, combining a detailed morphological study and molecular phylogenetic analyses, was applied in order to determine the species identity of these specimens. A principal components analysis of morphological data clustered the specimens from northwestern Argentina and from the Amazon basin, indicating a close morphological resemblance. Also, a molecular phylogenetic analysis showed populations of I. guttatus from Argentina and Peru forming a clade. According to the conducted haplotype network analysis these populations are distinct in two mutations. Thus, in absence of morphological or molecular data indicating the contrary, the combined method supports the identity of the specimens from the tributaries of the Paraguay River in Argentina as Imparfinis guttatus, whose type locality is in the upper Beni River basin in Bolivia. This contribution is also the first record for this species from Argentina. The disjunct distribution of I. guttatus provides new evidence reinforcing the hypothesis for the origin of the Paraguayan ichthyofauna. We also provide an approach to the phylogenetic relationships of Imparfinis in Heptapteridae. We applied an integrative approach to taxonomy, including morphological, phylogenetic and haplotype network analyses in order to assess the specific status of specimens of Imparfinis collected in Argentina. Theses analyses allows us to identify the specimens as This article is protected by copyright. All rights reserved. Imparfinis guttatus, expanding its distributional range. The disjunct distribution shown by I. guttatus represents new evidence on the origin of Paraguayan ichthyofauna. Also we provide the most comprehensive phylogenetic analysis of the relationships of Imparfinis in Heptapteridae.
... The genus Hypostomus Lacépède, 1803, with approximately 142 valid species, is the most speciose within the family Loricariidae (Lujan et al., 2015;de Queiroz et al., 2020;Fricke et al., 2021;Penido et al., 2021). Over the last years, this group has been the focus of many systematic studies due to its taxonomic complexity (Montoya-Burgos, 2003;Cardoso et al., 2012;Silva et al., 2016;de Oliveira Brandão et al., 2018;Dias, Zawadzki, 2018;Cardoso et al., 2019;Anjos et al., 2020;de Queiroz et al., 2020). Species of Hypostomus are morphologically characterized by having a dorsoventrally flattened body covered by bony plates, and for inhabiting the most diverse kind of habitats, from fast-flowing rivers with rocky bottom to lentic and turbid water and muddy substrate (Weber, 2003;Casatti et al., 2005;Lujan et al., 2015;Sá-Oliveira, Isaac, 2015). ...
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The species of Hypostomus from the Parnaíba River basin were reviewed through molecular and morphological analysis. Five species were found in the basin, including a new species herein described. The distribution of H. pusarum was expanded to this basin, and a closely related species was recorded (H. aff. pusarum), also the presence of H. johnii and H. vaillanti was confirmed. The new species is distinguished from most congeners by its large number of premaxillary and dentary teeth, a wide dental angle of 115° to 135°, presence of a rounded dark spots on a lighter background and anteromedial region of the abdomen depleted of plaques (vs. anteromedial region of the abdomen covered by platelets and odontodes in H. johnii, H. pusarum, H. aff. pusarum and H. vaillanti). Furthermore, an identification key of the species from the Maranhão-Piauí ecoregion and maps with the geographic distribution of these species are presented. The species of Hypostomus in the Parnaíba River basin have different geographic distributions, suggesting different niches or geographical barriers, providing an opportunity for ecological and evolutionary studies.
... Abbreviation: Ma, millions of years ago.suckermouth catfishes (Hypostominae) originated during the Eocene in the POA, dispersed to uplands of the Paraná river basin, and experienced accelerated rates of speciation and ecomorphological diversification during the Miocene(Cardoso et al., 2012;Silva et al., 2016). Species of the characiform clades Salminus(Bryconidae) and Schizodon (Anostomidae) and freshwater stingrays (Potamotrygoninae) represent other examples of dispersal from the Proto-Amazon to upland basins of the Brazilian and Guiana Shield, such as Araguaia-Tocantins, La Plata, São Francisco, Parnaíba, and Xingu, among others ...
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The Neotropics harbors a megadiverse ichthyofauna comprising over 6300 species with approximately 80% in just three taxonomic orders within the clade Characiphysi. This highly diverse group has evolved in tropical South America over tens to hundreds of millions of years influenced mostly by re-arrangements of river drainages in lowland and upland systems. In this study, we investigate patterns of spatial diversification in Neotropical freshwater fishes in the family Curimatidae, a species-rich clade of the order Characiformes. Specifically, we examined ancestral areas, dispersal events, and shifts in species richness using spatially explicit biogeographic and macroevolutionary models to determine whether lowlands–uplands serve as museums or cradles of diversification for curimatids. We used fossil information to estimate divergence times in BEAST, multiple time-stratified models of geographic range evolution in BioGeoBEARS, and alternative models of geographic state-dependent speciation and extinction in GeoHiSSE. Our results suggest that the most recent common ancestor of curimatids originated in the Late Cretaceous likely in lowland paleodrainages of northwestern South America. Dispersals from lowland to upland river basins of the Brazilian and Guiana shields occurred repeatedly across independently evolving lineages in the Cenozoic. Colonization of upland drainages was often coupled with increased rates of net diversification in species-rich genera such as Cyphocharax and Steindachnerina. Our findings demonstrate that colonization of novel aquatic environments at higher elevations is associated with an increased rate of diversification, although this pattern is clade-dependent and driven mostly by allopatric speciation. Curimatids reinforce an emerging perspective that Amazonian lowlands act as a museum by accumulating species along time, whereas the transitions to uplands stimulate higher net diversification rates and lineage diversification.
... Hypostomus constitutes an assemblage of more than 150 species of bottom-dwelling fishes with algivorous or detritivore diets that are widely distributed throughout South America (Fricke et al. 2021). Within the La Plata Basin (which includes the Paraguay, Paraná, Uruguay and Río de La Plata rivers) the diversity of species of this genus is being revised (Cardoso et al. 2011(Cardoso et al. , 2012(Cardoso et al. , 2016(Cardoso et al. , 2019. However, there are still many studies to be done given problems within the genus, the excessively short original descriptions of many species and the mistaken species identifications, including in scientific collections. ...
Article
In recent years, the evolutionary history of the catfish genus Hypostomus has attracted much interest (Cardoso et al. 2021; Jardim de Queiroz et al. 2020; Silva et al. 2016). However, the identification of species of this genus is challenging, given the complex taxonomy of the group and the scarce morphological information available for many taxa. Accurate taxonomic identification is essential to estimate the biodiversity in freshwater environments and the discovery of new fish species contributes not only to assess the diversity of regional fauna but also to reconstruct the geomorphological evolution of the river basins, notably in South America. The application of multi-source approaches takes advantage of the complementarity between disciplines to estimate the species diversity, especially among those with an obscure taxonomic status (Dayrat 2005).
... Hypostomus species are bottom-dwelling fish, with jaw specializations that allow them to combine mouth suction and mobile dentition to grasp and explore benthic substrata (Schaefer and Lauder, 1986). In addition, the genus Hypostomus is one of the most diverse freshwater catfish groups (Cardoso et al., 2012) and is often resistant to aquatic pollution since they utilize accessory breathing (Val and de Almeida-Val, 1995) when water conditions are severely hypoxic. Therefore, we analyzed the δ 15 N of periphyton and the periphyton consumer (Hypostomus) from a set of sites of the Rio das Velhas basin. ...
Article
Environmental disasters affecting Brazilian rivers have been frequent recently, especially involving mining activities. Two recent dam‐rupture events suddenly released millions of cubic meters of iron tailings downstream into two major Brazilian watersheds. These events generated major losses to the environment and human life. Additionally, the biodiversity in both watershed was still incompletely known. Two new species of the armored catfish genus Hypostomus were discovered in the the Rio Paraopeba and surrounding rivers of the Rio São Francisco Basin. The species share some main characteristics including a depressed body, large dark spots on a clearer background and the absence of keels on flanks. However, while one species (Hypostomus freirei sp. n.) has a large mandibular ramus and numerous slender teeth, the other (Hypostomus guajupia sp. n.) has a shorter mandibular ramus and few robust teeth. The discovery of these two new mid‐sized fish species emphasizes the presumption that the effects of major environmental disasters cannot be fully estimated as local biodiversity is not completely known. This discovery in a recently devastated area also shows that tough environmental laws of protection, supervision and mitigation of major impacts are urgently needed in developing countries. This article is protected by copyright. All rights reserved.
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A very simple, fast, universally applicable and reproducible method to extract high quality megabase genomic DNA from different organisms is decribed. We applied the same method to extract high quality complex genomic DNA from different tissues (wheat, barley, potato, beans, pear and almond leaves as well as fungi, insects and shrimps' fresh tissue) without any modification. The method does not require expensive and environmentally hazardous reagents and equipment. It can be performed even in low technology laboratories. The amount of tissue required by this method is ∼50–100 mg. The quantity and the quality of the DNA extracted by this method is high enough to perform hundreds of PCR-based reactions and also to be used in other DNA manipulation techniques such as restriction digestion, Southern blot and cloning.
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The present work extends to Argentina the distribution of Hypostomus aspilogaster originally described from Uruguay River in southern Brazil. The examined specimens were sampled in the stream Mandisoví Grande, affluent of Uruguay River in Entre Ríos province, and in Punta Lara, from Río de la Plata basin, in Buenos Aires province, Argentina. This represents the first country record for this species.
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A checklist of Recent and fossil catfishes (Order Siluriformes) is presented, summarizing taxonomic literature published through 2005. From 4624 nominal species group names and 810 genus group names, 3093 species are recognized as valid, and are distributed among 478 genera and 36 families. Distributional summaries are provided for each species, and nomenclatural synonymies, including relevant information on all name-bearing types, are included for all taxa. One new name is proposed herein: Clariallabes teugelsi, as a replacement for Clarias (Allabenchelys) dumerili longibarbis David & Poll, 1937, which is preoccupied by Clarias longibarbis Worthington, 1933, but has been treated as a valid species of Clariallabes by Teugels. Acrochordonichthys melanogaster Bleeker, 1854, is designated as type species of Acrochordonichthys Bleeker, 1857, inasmuch as no earlier valid designation has been found. A new genus Pseudobagarius, is proposed for the "pseudobagarius group" of species formerly placed in Akysis. The status of 228 species group names remains unresolved and 31 names based on otoliths ascribed to catfishes are listed but not placed into the checklist. The current emphasis given to catfish taxonomy at present is likely to result in a dramatic increase in the total number of valid taxa as well as major changes in the membership of some of the higher level taxa recognized here.
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Two new species of Hypostomus are described from the middle and upper rio Negro in Brazil. They are assigned to the Hypostomus cochliodon group (sensu Armbruster, 2003) by possessing few spoon-shaped teeth, and dentary angle averaging less than 80°. Hypostomus kopeyaka is described from the rio Tiquié, a tributary of the rio Uaupés, upper rio Negro basin, presents a unique color pattern among the Hypostomus species belonging to the Hypostomus cochliodon group, consisting of conspicuously horizontally elongated, closely-set black spots over the entire dorsal and lateral surfaces of the body. Hypostomus weberi is described from the middle rio Negro and can be distinguished from all remaining Hypostomus species belonging to the Hypostomus cochliodon group by possessing a unique color pattern consisting in large, rounded, widely-spaced black spots over body and fins. Duas novas espécies de Hypostomus são descritas para a bacia do alto e médio rio Negro no Brasil. Elas são atribuídas ao grupo Hypostomus cochliodon (sensu Armbruster, 2003) por possuírem poucos dentes, em forma de colher e ângulo entre os dentários menor que 80°. Hypostomus kopeyaka, descrita do rio Tiquié, um afluente do rio Uaupés, bacia do alto rio Negro, apresenta um padrão de colorido único entre as espécies de Hypostomus pertencentes ao grupo Hypostomus cochliodon, que consiste em manchas escuras conspícuas horizontalmente alongadas e próximas entre si sobre toda a superfície dorso-lateral do corpo. Hypostomus weberi, descrita do médio rio Negro, é distinguida de todas as espécies de Hypostomus pertencentes ao grupo Hypostomus cochliodon por possuir um padrão de colorido único que consiste em grandes manchas escuras e arredondadas, relativamente afastadas entre si, sobre toda a superfície do corpo e nadadeiras.
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Uma espécie nova de Hypostomus é descrita do rio Cuiabá, bacia do alto rio Paraguai, Estado do Mato Grosso, Brasil. A espécie nova é diagnosticada de todas as outras congêneres, com exceção de H. latifrons, pela presença de amplas barras escuras transversais nas laterais do corpo e nadadeiras, e pelas conspícuas vermiculações escuras na região abdominal. De H. latifrons ela difere por ter somente uma placa pré-dorsal margeando o osso supraoccipital e pela manutenção das barras escuras transversais nos adultos. Somada a outras espécies de peixes recentemente descritas na bacia do alto rio Paraguai, este trabalho demonstra que a região ainda funciona como uma fonte potencial de espécies novas.
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The recently-developed statistical method known as the "bootstrap" can be used to place confidence intervals on phylogenies. It involves resampling points from one's own data, with replacement, to create a series of bootstrap samples of the same size as the original data. Each of these is analyzed, and the variation among the resulting estimates taken to indicate the size of the error involved in making estimates from the original data. In the case of phylogenies, it is argued that the proper method of resampling is to keep all of the original species while sampling characters with replacement, under the assumption that the characters have been independently drawn by the systematist and have evolved independently. Majority-rule consensus trees can be used to construct a phylogeny showing all of the inferred monophyletic groups that occurred in a majority of the bootstrap samples. If a group shows up 95% of the time or more, the evidence for it is taken to be statistically significant. Existing computer programs can be used to analyze different bootstrap samples by using weights on the characters, the weight of a character being how many times it was drawn in bootstrap sampling. When all characters are perfectly compatible, as envisioned by Hennig, bootstrap sampling becomes unnecessary; the bootstrap method would show significant evidence for a group if it is defined by three or more characters.