Corresponding author: Rupert A. Collins (
Academic editor: John Friel
The Rio Nhamundá is a poorly-known clearwater river draining the southern Guiana Shield of Brazil. In this study we report the findings of a preliminary ichthyological survey, focusing on catfishes (
O Rio Nhamundá é um rio de água clara, pouco conhecido, que drena parte do Escudo das Guianas em território brasileiro. Nesse estudo, nós reportamos os resultados de um levantamento ictiofaunístico preliminar dessa área, tendo como foco os bagres (
The Rio Nhamundá is one of the south-draining Guiana Shield tributaries of the Rio Amazonas, Brazil. The river is located between the Uatumã-Jatapú and Trombetas rivers (Fig.
The ichthyofauna of the southern Guiana Shield rivers is poorly known in comparison to the northern Brazilian Shield rivers (
The aim of this study is to assess our current knowledge of
In order to assess the current knowledge of the catfishes of the Rio Nhamundá we carried out a survey of Web databases as well as published checklists and literature. The Web databases searched were FishBase (
Fishes were collected during the November 2013 dry season using a combination of methods mostly targeting larger species: gill netting, rod and line fishing, spear fishing, hand netting, and hand catching using snorkelling equipment. Fishes were photographed alive whenever possible following the recommendations outlined in
Our survey of the Rio Nhamundá was undertaken at seven main sampling locations on the lower reaches of the river, and these are shown in Fig.
Sampling site NH01 comprised a small rocky promontory of a black lateritic conglomerate layer forming part of the island town of Nhamundá (Fig.
Sampling site NH04 comprised a fairly typical representation of the upstream section of the river, mainly characterised by the presence of woody debris (Fig.
Measurements of preserved material were taken with dial callipers to a precision of 0.1 mm. All measurements and counts for symmetrical features were taken from the left side of the specimen. For loricariids, measurements and meristic counts follow
We used published literature to identify the specimens collected during our fieldwork, and we also provide here the characters found in those references that we used to make each identification. The identifications of the specimens from the INPA collection were also cross-checked. When required, we examined photographs of type material on the All Species Catfish Inventory Web page (
We try to keep terminology consistent across species, but also attempt to maintain a degree of agreement with original authors' work in order to aid in referring back to their characters. For example, when reporting the
We were conservative in applying names to the specimens collected, i.e. individuals were assigned to nominal species wherever possible, especially in cases where no modern literature for the group was available. In order to differentiate undetermined from undescribed species, we use consistent and informative tag-names following
DNA barcodes were generated for at least one individual per species. Methodology for DNA extraction, PCR and sequencing follows
We also searched the Barcode of Life Data Systems (BOLD;
This record of a single specimen from the INPA fish collection comprises an undescribed
Record follows data from a single specimen in the collection of fishes at INPA.
Identification to species level follows
Three individuals were caught by hand from their lodgements in woody substrates at the margin of the main river (sampling site NH04). An example of a live specimen is pictured in Fig.
Identification as a possibly undescribed species similar to
Specifically, our specimens differ from
Sixteen individuals were caught either by hand from their lodgements in woody substrates (sampling sites NH04 and NH08), or more effectively using a hand net at the surface after attracting insects—on which they were feeding—with a light (sampling site NH12); under such conditions they appeared abundant on the lower Nhamundá. An example of a live specimen is pictured in Fig.
Two lots of
Identification to species level follows
Four individuals were caught by hand from their lodgements in woody substrates at the margin of the main river (sampling site NH04). The species was also observed in rocky habitats (sampling sites NH08 and NH12), but were more difficult to catch in this situation. An example of a live specimen is pictured in Fig.
Identification to species level follows
Two individuals were caught at night using gill nets set in the margins of the main river. An example of a live specimen is pictured in Fig.
Identification to species level follows
Two individuals were caught by hand-net at night over a sandy/silty substrate (sampling site NH12). An example of a live specimen is pictured in Fig.
Record follows data from
Record follows data from
Identification to species level for this specimen could not be adequately made using morphological characters due to the small size of the immature specimen. However, rather than exclude the individual, we compared the DNA barcodes to the COI sequences presented by
One individual was caught by hand-net on the Rio Paratucu (sampling site NH10). This specimen is pictured in Fig.
Identification to species level follows
One individual was caught by hand-net on the Rio Paratucu (sampling site NH10), and delivered a painful sting, confirming that many heptapterids are venomous (
Tentative identification to genus level follows
Given the large diversity of the group, and the paucity of modern treatments dealing with heptapterids, we are currently unable to identify this fish to species level, and our genus identification is tentative. Important characters include the caudal fin lobes of approximately equal length, maxillary barbels not surpassing anal fin (left barbel is damaged in our specimen), the complete lack of dark longitudinal stripe, the wedge-shaped mark on the dorsal-fin, and the dark saddle anterior to the dorsal fin.
One individual was caught by hand-net on a sandy beach habitat (adjacent to sampling site NH05). This specimen is pictured in Fig.
Identification to species level follows
Thirteen individuals were caught by hand from submerged terrestrial vegetation (sampling site NH02). An example of a live specimen is pictured in Fig.
Identification to species level follows
We note that
Eleven individuals were caught by hand on both woody (sampling site NH04) and rocky substrates (sampling site NH01). The species appeared abundant throughout the river. An example of a live specimen is pictured in Fig.
Following
Among the superficially similar nominal
Two individuals were caught by hand at night from rocky substrates (sampling site NH01). An example of a live specimen is pictured in Fig.
Identification to species level follows
Nine individuals were caught by hand from woody substrates (sampling sites NH04 and NH08). In addition to the main river stem, the species was also observed in lake and igarapé habitats, and appeared abundant. It was not found in association with rocks. An example of a live specimen is pictured in Fig.
Following
The
Twelve individuals were caught by hand at night from rocky substrates (sampling site NH01). Four examples of live specimens are pictured in Fig.
Identification to species level follows
Four individuals were caught by hand from woody substrates at the margin of the main river (sampling sites NH04 and NH08). An example of a live specimen is pictured in Fig.
Identification to species level follows
One individual was caught by hand from woody substrates at the margin of the main river (sampling site NH08). An example of a live specimen is pictured in Fig.
Record follows data from a single specimen in the collection of fishes at INPA.
Identification to species level follows
Two individuals were caught by hand from woody substrates at the margin of the main river (sampling sites NH05 and NH08). An example of a live specimen is pictured in Fig.
Identification to species level follows
Three individuals were caught by hand from woody substrates at the margin of the main river (sampling site NH04). An example of a live specimen is pictured in Fig.
Identification to species level follows
An interesting observation is that our specimens exhibited variation in terms of the degree of abdomen plating and markings: adult specimens from collection points near the mouth of the river (sampling sites NH01, NH02 and NH12) showed complete abdominal plating and a vermiculated pattern (Fig.
Twenty-eight individuals were caught by hand from both woody substrates (sampling sites NH02, NH04, NH05, and NH08) and rocky substrates (sampling sites NH01 and NH12). Two further specimens of this species are reported from the collection of fishes at INPA.
Identification to genus level follows
Using the above references we were unable to identify the specimens to species level, as the individuals differed from the colour patterns diagnostic of the other species in the genus. We hypothesise that these individuals represent a new species of
Seventeen individuals were captured by hand from crevices in rocky habitats exposed to strong current (sampling site NH08). Live colouration is shown in Fig.
Identification to species level follows
The above characters are consistent with
One individual was caught by hand from shallow, fast flowing water over a rocky/sandy substrate (sampling site NH05). The live specimen is pictured in Fig.
Record follows data from a single specimen in the collection of fishes at INPA. The specimen had been identified there as
Identification to species level follows
One individual was caught by hand from shallow, fast flowing water over a rocky/sandy substrate (sampling site NH05). The live specimen is pictured in Fig.
Identification to species level follows
Three adult individuals were caught by hand-net at night over a sandy/silty substrate (sampling site NH12), and four juveniles were caught further upstream on the sandy margins of the river (sampling site NH05). An example of a live adult specimen is pictured in Fig.
One further specimen record of this species was obtained from the fish collection at INPA; this individual had been identified as
Identification to species level follows
Two individuals were caught by hand from shallow, fast flowing water over a rocky/sandy substrate on the main river (sampling site NH05). A live specimen is pictured in Fig.
Identification to species level follows
Five individuals were caught after being attracted to the boat by suspending a dead-fish bait in the water (sampling site NH12). An example of a live specimen is pictured in Fig.
Identification to species level follows
One individual was caught by baited hand-line in a deep pool of the main river. The live specimen is pictured in Fig.
Record follows data from a single specimen in the collection of fishes at INPA.
Identification to species level follows
One individual was caught by gill net, but was not vouchered or photographed.
Identification to species level follows
While we follow the taxonomy of
Four individuals were caught at night using gill nets in a lake connected to the river. An example of two live specimens is pictured in Fig.
Identification to species level follows
An important inconsistency should be noted regarding the caudal fin shape.
Four individuals were caught by hand from their lodgements in woody substrates at the margin of the main river (sampling site NH04). An example of a live specimen is pictured in Fig.
Record follows data from
Our survey of the online databases revealed a single species record from the Rio Nhamundá: an unidentified
The collection of fishes at INPA held nine lots of catfishes previously collected from the Nhamundá. One of these records (
Our review of the genetic databases shows GenBank holds COI data for nine of the 24 species we obtained DNA barcodes from and identified as a known species (number of records in parentheses):
In addition to the species listed above and available in GenBank, we provide COI data for 17 putative species with no current sequences apparently available in either GenBank or BOLD:
Our desk and museum collection surveys show that few ichthyological surveys of the Rio Nhamundá have taken place, and that our collection is one of the first to be made on the river. Not including the unverified
The checklist is far from complete, however, missing entirely families such the callichthyids and aspredinids, although we sampled habitats most likely to yield these groups, such as igarapés, only superficially. Despite this, we feel that rapid publication of even modest datasets and small-scale surveys can make valuable additions to biodiversity science in the Amazon by both presenting the early discovery of new species and the extension of ranges for known species. The study also highlights the paucity of neotropical ichthyological data in GBIF/GenBank, and makes a small contribution.
The biogeographic composition of the collection is interesting. While many of the species recorded were cosmopolitan inhabitants of the lowland Amazon—e.g.
In summary, the Rio Nhamundá may therefore be an important sampling location for uncovering biogeographic patterns of fishes of the Lower Amazon and Guiana Shield. Of more urgent importance, however, is the sensitivity of freshwater ecosystems to anthropogenic activities and the requirement for catchment-specific conservation plans (
We thank Manoel Torres for the use of his boat, as well as Silvio, Maria and Moura for their assistance, hospitality, and collecting expertise during our trip on the Rio Nhamundá. We also thank John Friel, Nathan Lujan, Jonathan Armbruster, José Birindelli, and an anonymous reviewer for suggesting improvements to the paper. We are also grateful to Cláudio Zawadzki for offering his advice with the identification of the
Location of the Rio Nhamundá and neighbouring rivers. Inset shows wider Amazon region. Map was created in QGIS (
Location of sampling sites on the Rio Nhamundá. Map was created with the R package ggmap (
Images of the Rio Nhamundá showing the two distinctive environment types.
Narrow upstream section near sample site NH05.
Lake-like lower section at the town of Nhamundá, near sample site NH01.
Habitat descriptions of sampling locations.
Exposed laterite boulders at sampling site NH01.
Underwater view of rocks and substrate at sampling site NH01.
Exposed laterite boulders at sampling site NH12.
River near sampling site NH04.
Underwater view of woody substrates at sampling site NH04 (with
Fast current flowing over exposed bedrock at sampling site NH08.
Lateral view.
Dorsal view showing body shape.
Lateral view, 68.6 mm SL.
Lateral view, 60.8 mm SL.
Lateral view, 73.1 mm SL. Image flipped horizontally.
Lateral view, 64.3 mm SL.
Lateral view (102.5 mm SL; INPA 43869; UFAM:CTGA:14546).
Ventral view (102.5 mm SL; INPA 43869; UFAM:CTGA:14546).
Lateral view (99.7 mm SL; INPA 43894; UFAM:CTGA:14334).
Ventral view (99.7 mm SL; INPA 43894; UFAM:CTGA:14334).
Lateral view (115.6 mm SL; INPA 43881; UFAM:CTGA:14316).
Ventral view (115.6 mm SL; INPA 43881; UFAM:CTGA:14316).
R script to access GBIF and FishBase records
Data type: Plain text file (R script)
File: oo_42806.R
Bash script to search locally stored checklists in PDF format
Data type: Plain text file (bash script)
File: oo_42807.sh