Corresponding author: Gilmar Perbiche-Neves (
Academic editor: D. Defaye
An identification guide is presented for species of calanoid copepod family
Perbiche-Neves G, Boxshall GA, Previattelli D, Nogueira MG, da Rocha CEF (2015) Identification guide to some Diaptomid species (Crustacea, Copepoda, Calanoida, Diaptomidae) of “de la Plata” River Basin (South America). ZooKeys 497: 1–111. doi:
Copepods are typically small crustaceans that are widely distributed in virtually all aquatic habitats from hot springs to glacial meltwater pools, and from deep ocean trenches to high altitude lakes (
In continental or inland waters, copepods are predominantly represented by three orders:
All the calanoids collected during our study belong to the subfamily
In South America, copepods of continental waters began to be studied from the 1890s, and several major works appeared in the 1920s and 1930s (e.g.
Although some of the studies were made many years ago, we found that the following papers, used jointly, are quite useful for identifying diaptomids in the region:
Net zooplankton samples were taken across “de la Plata” river basin in lotic stretches and in reservoirs (upstream to dam – intermediate zone –, and close to dam – lentic zone) (Figure
Map of sampling sites in de la Plata river basin. Reservoirs sampled included the first and the last in each regulated river as well as dam-free lotic stretches. Symbols differentiate between sites with water retention times (WRT) greater than (○) or less than (●) 100 days.
List of sampling sites. For each site a code is provided based on a 3 or 4 letter abbreviation of the name of the reservoir or river, and a 1 letter suffix. The suffixes used for reservoirs are: U = upstream and D = dam, and for rivers: H = high stretch, M = middle stretch, L = low stretch). Country abbreviations are: ARG = Argentina, BOL = Bolivia, BRA = Brazil, PAR = Paraguay, and URU = Uruguay. Geographical coordinates and altitude (m.a.s.l.) are also given.
N° | Codes | River/Reservoir | Coordinates | Alt. (m) |
---|---|---|---|---|
1 | EMB-U | Emborcação Reservoir – BRA |
|
634 |
2 | EMB-D | Emborcação Reservoir – BRA |
|
648 |
3 | SSIM-U | São Simão Reservoir – BRA |
|
402 |
4 | SSIM-D | São Simão Reservoir – BRA |
|
406 |
5 | FUR-U | Furnas Reservoir – BRA |
|
771 |
6 | FUR-D | Furnas Reservoir – BRA |
|
769 |
7 | AVER-U | Água Vermelha Reservoir – BRA |
|
388 |
8 | AVER-D | Água Vermelha Reservoir – BRA |
|
388 |
9 | BBON-U | Barra Bonita Reservoir – BRA |
|
463 |
10 | BBON-D | Barra Bonita Reservoir – BRA |
|
454 |
11 | TIRM-U | Três Irmãos Reservoir – BRA |
|
320 |
12 | TIRM-D | Três Irmãos Reservoir – BRA |
|
326 |
13 | JUR-U | Jurumirim Reservoir – BRA |
|
572 |
14 | JUR-D | Jurumirim Reservoir – BRA |
|
566 |
15 | ROS-U | Rosana Reservoir – BRA |
|
262 |
16 | ROS-D | Rosana Reservoir – BRA |
|
261 |
17 | FAR-U | Foz do Areia Reservoir – BRA |
|
754 |
18 | FAR-D | Foz do Areia Reservoir – BRA |
|
749 |
19 | SCAX-U | Salto Caxias Reservoir – BRA |
|
333 |
20 | SCAX-D | Salto Caxias Reservoir – BRA |
|
319 |
21 | ISOL-U | Ilha Solteira Reservoir – BRA |
|
332 |
22 | ISOL-D | Ilha Solteira Reservoir – BRA |
|
321 |
23 | ITA-U | Itaipu Reservoir – BRA/PAR |
|
217 |
24 | ITA-D | Itaipu Reservoir – BRA/PAR |
|
220 |
25 | YACI-U | Yaciretá Reservoir – ARG/PAR |
|
71 |
26 | YACI-D | Yaciretá Reservoir – ARG/PAR |
|
78 |
27 | RPAR-M1 | Paraná River – middle stretch – ARG |
|
43 |
28 | RPAR-M2 | Paraná River – middle stretch – ARG |
|
26 |
29 | RPAR-M3 | Paraná River – middle stretch – ARG |
|
21 |
30 | RPAR-L1 | Paraná River – low stretch – ARG |
|
5 |
31 | RPAR-L2 | Paraná River – low stretch – ARG |
|
5 |
32 | RPAR-L3 | Paraná River – low stretch – ARG |
|
5 |
33 | RPLA | Rio de la Plata – URU/ARG |
|
1 |
34 | RPAG-H | Paraguay River – high stretch – BOL/BRA |
|
94 |
35 | RPAG-M | Paraguay River – middle stretch – PAR/BRA |
|
71 |
36 | RPAG-L | Paraguay River – low stretch – ARG/PAR |
|
54 |
37 | MAC-U | Machadinho Reservoir – BRA |
|
476 |
38 | MAC-D | Machadinho Reservoir – BRA |
|
484 |
39 | RURU-M1 | Uruguay – middle stretch – ARG/BRA |
|
112 |
40 | RURU-M2 | Uruguay – middle stretch – ARG/BRA |
|
54 |
41 | SGRA-U | Salto Grande Reservoir – URU/ARG |
|
33 |
42 | SGRA-D | Salto Grande Reservoir – URU/ARG |
|
34 |
43 | RURU-L | Uruguay River – low stretch – URU/ARG |
|
8 |
The samples were collected by vertical hauls with a conical plankton net with a 68 µm mesh, equipped with an anti-reflux adaptation following
Back in the laboratory, the copepods were sorted and analysed under a stereo- microscope (Zeiss Stemi SV6 and Zeiss Discovery V20), or a binocular microscope (Zeiss Standard 20 and 25). Copepods were dissected with fine needles and semi-permanent slides were made in glycerine or in 70% lactophenol. Only adults were analysed.
Copepods were identified with the aid of a number of publications dealing with the taxonomy of
All original zooplankton samples are deposited in the Continental Water Microcrustacean Collection–CMAC, Department of Zoology, University of the State of São Paulo–UNESP, Botucatu campus. Vouchers of some species were deposited in the Museum of Zoology, University of São Paulo–MZUSP (São Paulo, Brazil), with registration numbers as follows:
Vouchers of the species
The keys presented in this guide were constructed using only differential characters that emerged as being consistently useful for the identification of genera and species. Similarly, the diagnoses were designed to focus on the basic features traditionally used to characterize diaptomid genera and species, as provided in the specialized taxonomic literature. The morphological structures used in this study are illustrated for both males (Figure
Key to the morphological structures of adult male diaptomids.
Key to the morphological structures of adult female diaptomids.
Key to male characters numbered in Figure
N | Structure name | Abbrev. | N | Structure name | Abbrev. |
---|---|---|---|---|---|
A | Distal prosome, urosome and P5 | C | Right geniculate antennule | A1R | |
1 | Pediger 5 | Ped5 | 1 | First segment of A1R | |
2 | Urosome somite 1 | Ur1 | 2 | Second segment of A1R | |
3 | Urosome somite 2 | Ur2 | 3 | Thirteenth segment of A1R | |
4 | Urosome somite 3 | Ur3 | 4 | Modified seta on segment 13 of A1R | |
5 | Urosome somite 4 | Ur4 | 5 | Fourteenth segment of A1R | |
6 | Caudal rami | CR | 6 | Spinous process on segment 14 of A1R | |
7 | Caudal setae | CS | 7 | Fifteenth segment of A1R | |
8 | Coxa of left P5 | CxP5L | 8 | Spinous process on segment 15 of A1R | |
9 | Sensilla of basipodite of left P5 | 9 | Sixteenth segment of A1R | ||
10 | Basipodite of left P5 | BspP5L | 10 | Twentieth segment of A1R | |
11 | Setae of basipodite of left P5 | 11 | Spinous process on segment 20 of A1R | ||
12 | Endopodite of left P5 | EnpP5L | D | Fifth leg anterior(P5) | |
13 | Apical setation of endopodite of left P5 | 1 | Coxa of right P5 | CxP5R | |
14 | First segment of exopodite of left P5 | Exp1P5L | 2 | Basipodite of right P5 | BspP5R |
15 | Second segment of exopodite of left P5 | Exp2PrL | 3 | Knob processes on internal margin of BspP5R | |
16 | Coxa of right P5 | CxP5R | 4 | Endopodite of right P5 | EnpP5R |
17 | Basipodite of right P5 | BspP5R | 5 | Coxa of left P5 | CxP5L |
18 | Lateral seta of basipodite of right P5 | 6 | Basipodite of left P5 | BspP5L | |
19 | Endopodite of right P5 | EnpP5R | 7 | Knob processes on internal margin of BspP5 | |
20 | First segment of exopodite of right P5 | Exp1P5R | 8 | Second segment of exopodite of left P5 | Exp2PrL |
21 | Second segment of exopodite of right P5 | Exp2P5R | E | Adult male | |
22 | Lateral spine of Exp2P5R | 1 | Left antennule | A1L | |
23 | Terminal claw of Exp2P5R | 2 | Right geniculate antennule | A1R | |
24 | Fifth leg | P5 | 3 | Spinous process on segment 20 of A1R | |
B | Right P5 | P5R | 4 | Pediger 3 | Ped3 |
1 | Coxa of right P5 | CxP5R | 5 | Pediger 4 | Ped4 |
2 | Distal projection of CxP5R | 6 | Genital segment or urosome segment 1 | GS or Ur1 | |
3 | Sensilla on top of distal projection of CxP5R | 7 | Urosome somite 2 | Ur2 | |
4 | Basipodite of right P5 | BspP5R | 8 | Rows of spinules on urosome somite 3 | |
5 | Lateral setae of BspP5R | 9 | Caudal rami | CR | |
6 | First segment of exopodite of right P5 | Exp1P5R | 10 | Caudal setae | CS |
7 | Distal projection of Exp1P5R | 11 | Right P5 | P5R | |
8 | Second segment of exopodite of right P5 | Exp2P5R | F | Border between pediger 3 and 4 | |
9 | Lateral spine of Exp2P5R | 1 | Row of spinules on distal margin of pediger 3 | ||
10 | Terminal claw of Exp2P5R |
Key to female characters numbered in Figure
N | Structure name | Abrev. | N | Structure name | Abrev. |
---|---|---|---|---|---|
A | P5 Left - caudal | D | Adult female | ||
1 | Coxa of left P5 | CxP5L | 1 | Left antennule | A1L |
2 | Basipodite of left P5 | BspP5L | 2 | Pediger 3 | Ped3 |
3 | Lateral setae of BspP5L | 3 | Pediger 4 | Ped4 | |
4 | Endopodite of left P5 | EnpP5L | 4 | Lateral wing of prosome pediger 5, with apical sensilla | |
5 | Terminal spinules on endopodite of left P5 | 5 | Expansions of genital double somite, with sensilla | ||
6 | First segment of exopodite of left P5 | Exp1P5L | 6 | Genital double somite | GS |
7 | Second segment of exopodite of left P5 | Exp2P5L | 7 | Caudal rami | CR |
8 | Lateral seta of Exp2P5L | 8 | Caudal setae | CS | |
9 | External seta of Exp3P5L | E | Distal part of prosome and genital segment | ||
10 | Internal seta of Exp3P5L | 1 | Prosome pediger 3 | Ped3 | |
11 | Terminal claw of left P5 | 2 | Lines of spinules on distal dorsal margin of Ped3 | ||
12 | Rows of spinules on terminal claw of left P5 | 3 | Prosome pediger 4 | Ped4 | |
B | P5 left – frontal | 4 | Rows of spinules on distal margin of Ped4 | ||
1 | Coxa of left P5 | CxP5L | 5 | Left lateral wing of pediger 5, with apical sensila | |
2 | Distal projection of CxP5L | 6 | Sensila of right lateral wing of pediger 5 | ||
3 | Sensilla on apex of distal projection of CxP5L | 7 | Left lateral wing of pediger 5 | ||
4 | Basipodite of right P5 | BspP5R | 8 | Genital double somite | GS |
5 | Lateral seta of BspP5L | 9 | Sensilla at apex of right lateral expansion of GS | ||
6 | Endopodite of left P5 | EnpP5L | 10 | Expansions of genital segment, with sensilla | |
7 | Concavity in endopodite of left P5 | F | Distal part of prosome and genital double somite | ||
8 | Terminal spinules on endopodite of left P5 | 1 | Prosome 5, with rows of spinules on distal margin | ||
9 | First segment of exopodite of left P5 | Exp1P5L | 2 | Dorsal/lateral setules on Ped4 and Ped5 | |
10 | Second segment of exopodite of left P5 | Exp2P5L | 3 | Incomplete suture between Ped4 and Ped5 | |
11 | Lateral seta of Exp2P5L | 4 | Left lateral wing of Ped5 | ||
12 | Third segment of exopodite of left P5 | Exp3P5L | 5 | Sensilla at apex of left lateral wing of Ped5 | |
13 | External seta of Exp3P5L | 6 | Right lateral wing of Ped5 | ||
14 | Internal seta of Exp3P5L | 7 | Sensilla at apex of right lateral wing of Ped5 | ||
15 | Terminal claw of left P5 | 8 | Genital double somite | GS | |
16 | Rows of spinules on terminal claw of left P5 | 9 | Sensilla on lateral margin expansion of GS | ||
C | Second exopodite and terminal claw | 10 | P5 | P5 | |
1 | Second segment of exopodite of right P5 | Exp2P5R | 11 | Right distal margin expansion of GS | |
2 | Lateral seta of Exp2P5R | ||||
3 | External seta of Exp3P5R | ||||
4 | Internal seta of Exp3P5R | ||||
5 | Terminal claw of left P5 | ||||
6 | Rows of spinules on terminal claw of left P5 |
Morphological structures were illustrated using phase contrast microscopy (Zeiss Standard) with the aid of a drawing tube. The pencil drawings were inked in nankeen ink, then scanned and corrected for smudges and other imperfections in Adobe Photoshop 7.0 in order to obtain high-quality illustrations.
We remind users of the keys that many structures illustrated in Figures
The scanning electron microscopy (SEM) was carried out in the “Electron Microscopy Center (CME)” of the University of the State of São Paulo–UNESP – Botucatu, Brazil. Material was prepared by packing each sample of individuals in hollow cylindrical polyethylene compartments, within which the copepods were washed, fixed and dehydrated. Washing was performed using 0.1 M phosphate buffer at pH 7.3 (3 washes, each for 5 min). After washing specimens were immediately fixed by immersion in 0.5% osmium tetroxide (in water) for 20 min. Dehydration was performed progressively via a graded series of ethanol as follows: 7.5%, 15%, 30% and 50% (two changes at each concentration for 5 min), then 70% (3 changes each for 10 min), and 90% and 100% (2 changes at each, for 5 min). Subsequently, the material was critical point dried in a BALZERS UNION CTD-020 equipment, using liquid carbon dioxide as the exchange medium. After drying, specimens were dissected when necessary to reveal diagnostic structures, and attached to stubs using adhesive tape. Sputter coating with 15 nm layer of gold was carried out in a BALZERS UNION MED-10 coater. Observations were made on a Philips SEM-515 microscope and images were edited in Photoshop 7.0 (Adobe).
1 | BspP5 with groups of small spinules on inner margin of both or one pediger | |
– | BspP5 with smooth inner margin |
|
2 | CR with semi-circular protuberance at inner distal corner |
|
– | CR without semi-circular protuberance at inner distal corner |
|
3 | Right Exp2P5 subtriangular, 1.1–1.2 times wider than long (Fig. |
|
– | Right Exp2P5 >1.2 longer than wide |
|
4 | Right Exp2P5 with lateral spine inserted proximally on margin of segment |
|
– | Right Exp2p5 with lateral spine inserted in middle of segment or sub-terminally | |
5 | Lateral spine of Exp2P5R inserted at about 1/3 distance between base of segment and terminal claw (Fig. |
|
– | Lateral spine of Exp2P5R inserted at more than 1/3 distance between base of segment and terminal claw |
|
6 | Insertion of lateral spine of Exp2P5R separated from base of terminal claw by gap greater than width of base of lateral spine (Fig. |
|
– | Lateral spine of right Exp2P5 inserted distally very close to base of terminal claw (Fig. |
|
7 | Posterior margins of Ped 4 and Ped5 lacking ornamentation of spinules; A1R with spinous process on segment 14; internal margin of right BspP5 lacking proximal expansion |
|
– | Posterior margins of Ped4 and Ped5 ornamented with dorsal spinules; segment 14 of A1R lacking spinous process; internal margin of right BspP5 with proximal expansion reaching and overlapping left BspP5 |
|
8 | Lateral spine of right Exp2P5 less than 1/5 (20%) length of terminal claw (Fig. |
|
– | Lateral spine of right Exp2P5 more than 1/5 (20%) length of terminal claw |
|
9 | Lateral spine of right Exp2P5 inserted proximally, distant from base of terminal claw (e.g. Fig. |
|
– | Lateral spine of right Exp2P5 inserted distally, close to base of terminal claw (Fig. |
|
10 | First segment of A1R lacking rows of spinules |
|
– | First segment of A1R ornamented with rows of spinules |
|
11 | Spinous process on anterior margin of segment 15 of A1R short, not reaching proximal border of segment 16 (Fig. |
|
– | Spinous process on anterior margin of segment 15 of A1R long (reaching about midlength of segment 16) (Fig. |
|
12 | Segment 11 of left A1 lacking setae; small granulations absent from fissure in surface of right BspP5; internal margin of right BspP5 with proximal expansion reaching and overlapping left P5 |
|
– | Segment 11 of left A1 armed with two setae (Fig. |
|
13 | Lateral spine of Exp2P5R short, between 1/5 and 1/3 the length of terminal claw (Fig. |
|
– | Lateral spine of Exp2P5R relatively long, more than 1/3 the length of terminal claw (Fig. |
|
14 | Proximal inner margins of left and right BspP5 lacking sclerotized semi-circular processes |
|
– | Proximal inner margin of BspP5 bearing one large sclerotized semi-circular process on right leg and two smaller processes on same segment of left leg (Figs |
|
15 | Right Exp1P5 longer than wide; at least four small sclerotized processes present on posterior surface of right Exp2P5 (Fig. |
|
– | Right Exp1P5 wider than long; no sclerotized processes present on posterior surface of right Exp2P5, but single inner margin process present (Fig. |
|
16 | Lateral spine of right Exp2P5 located about at midlength of external margin (Fig. |
|
– | Lateral spine of right Exp2P5 not strongly curved, located on distal margin; segments 15 and 16 of A1R lacking well developed spinous processes; posterior margins of Ped4 and Ped5 lacking ornamentation of spinules |
|
17 | Lateral spine of right Exp2P5 inserted some distance from base of terminal claw (Fig. |
|
– | Lateral spine of right Exp2P5 inserted almost adjacent to base of terminal claw (Figs |
|
18 | Distal margin of segment 20 of A1R with simple distally-tapering process (Fig. |
|
– | Distal margin of segment 20 of A1R with short, apically bifid process (Fig. |
|
1 | Lateral wings with two lobes on each side (Fig. |
|
– | Lateral wings with one lobe on each side, with two pairs of sensillae, one large pair at apex and smaller pair on internal part of dorsal surface (Fig. |
|
2 | Posterior margins of Ped4 and Ped5 ornamented with rows of small dorsal spinules |
|
– | Posterior margins of Ped4 and Ped5 without rows of spinules |
|
3 | EnpP5 long, reaching distal end of inner margin of Exp1P5 (Fig. |
|
– | EnpP5 short, not reaching distal end of inner margin of Exp1P5 |
|
4 | Longest distal spine on EnpP5 about half as long as endopod (Fig. |
|
– | Longest distal spine on EnpP5 less than half length of ramus; sensillae on swellings of GS asymmetrical, left sensilla larger and more robust than right, approximately 2.8 times longer than wide and directed more strongly backwards than right sensilla |
|
5 | GS strongly asymmetrical, with well-developed posterior lobe on right side, extending beyond distal margin of GS; small sclerotized lobes present posteriorly on dorsal surface on left side of GS (Fig. |
|
– | Posterior lobe on right side of GS weakly developed or absent; no small processes present dorsally on left side of GS or on left lateral margin of Ur3; CxP5 without small sclerotized process on distal lobe |
|
6 | Lateral wings larger and projecting further posteriorly on left side than on right (Fig. |
|
– | Lateral wings of Ped5 symmetrical or slightly asymmetrical; swellings on GS without hemispherical lobes on both sides |
|
7 | Transverse row of spinules marking position of posterior margin of Ped5; GS asymmetrical, with left swelling larger than right, and hemispherical in form; sensilla on left swelling directed slightly posteriorly, sensilla on right directed anteriorly (Fig. |
|
– | These characters not combined | |
8 | Posterior margins of Ped4 and/or Ped5 with rows of spinules on dorsal surface |
|
– | Posterior margins of Ped4 and Ped5 lacking spinule rows dorsally |
|
9 | Rows of spinules present on dorsal surface of posterior margins of both Ped4 and Ped5 |
|
– | Rows of spinules present dorsally on posterior margin of Ped5 only |
|
10 | Single row of strong spinules present on posterior margin of Ped3, irregular rows of medium-sized spinules present on Ped4, and row of small spinules present on Ped5; lateral wings of Ped5 asymmetrical and elongate, left wing curved slightly anteriorly and right wing directed posteriorly (Fig. |
|
– | Multiple rows of small spinules present on posterior margin of Ped4; lateral wings of Ped5 slightly asymmetrical, not elongate; GS with hemispherical swelling only on left side, left sensilla directed posteriorly; EnpP5 long, reaching beyond middle of inner margin of Exp1P5 (Fig. |
|
11 | Irregular and multiple rows of hair-like spinules present on dorsal and lateral surfaces of Ped5 |
|
– | Simple row or rows of spinules present dorsally along posterior margin of Ped5, spinules short and robust, not hair-like |
|
12 | Row of small spinules present, marking plane of incomplete suture between Ped4 and Ped5; lateral wings of Ped5 asymmetrical, projecting laterally (Fig. |
|
– | Lateral wings of Pr5 not projecting laterally; asymmetrical in shape |
|
13 | Lateral wings of Ped5 asymmetrical, left sensilla directed posteriorly (Fig. |
|
– | Lateral wings symmetrical or slightly asymmetrical; sensilla on lateral wing on left side of Ped5 directed posterolaterally, not posteriorly; right margin of GS lacking postero-distal lobe; internal seta on tip of Exp3P5 less than 4 times as long as external seta |
|
14 | Complete single row and short double row of spinules present dorsally near posterior margin of Ped4 (Figs |
|
– | Lines of spinules present on Ped4 border; lateral wings of Ped5 clearly asymmetrical, with apical (outer) sensilla about 2.2 to 2.3 times longer than wide; inner sensilla on lateral wings well developed (Fig. |
|
15 | Dorsal projection present on Ped4 (Fig. |
|
– | Ped4 lacking such dorsal projection |
|
16 | Inner right sensilla on lateral wing of Ped5 short, setule-like; GS asymmetrical, right sensilla about 2.3 times longer than wide, inserted on hemispherical lobe; right margin of GS with rounded lobe at posterior end (Fig. |
|
– | Inner right sensilla of Ped5 not setule-like; GS right sensilla present but inserted in different position, no hemispherical lobe present on right side of GS at insertion of sensilla |
|
17 | Lateral wings of Ped5 projecting posteriorly; inner sensilla on Ped5 short with broad base (Fig. |
|
– | Lateral wings of Ped5 not projecting posteriorly; position of inner sensilla on Ped5 variable; GS about 1.6 times longer than wide; sensilla on left swelling of GS directed slightly posteriorly, right sensilla directed slightly anteriorly; sensilla on CxP5 about 1.5 times longer than wide; external seta on Exp3P5 about half length of internal seta |
|
18 | Sensillae on both swellings on GS directed perpendicular to body axis; right margin of GS with small rounded lobe at posterior extremity (Fig. |
|
– | Sensilla on right swelling on GS directed posteriorly; right margin of GS without posterior lobe (Fig. |
|
In identifying species of
Ultrafine-scale ornamentation characters might prove to be valuable in future comparative studies, including 1) the presence of a pore on segment 20 of male A1R (Fig.
This species is widely distributed, extending from northeastern Brazil to the Itaipu Reservoir at the end of the upper Paraná River in southern Brazil (Fig.
Geographical distribution of
SEM photographs.
The male illustrated was collected from the Salto Grande reservoir (SGRA-D), Uruguay River. The female illustrated here belongs to the collection of the Museo Argentino de Ciencias Naturales (Buenos Aires) (MACN-In 29733), and was examined because of the scarcity of females in the samples from de la Plata river basin. This species can be readily identified because of the distinctive structure of its P5 and the presence of dorsal rows of spinules on the male pedigers, which are lacking in other species of
This species is common in the lower regions of the basins of the Paraná and Uruguay rivers (Figure
Geographical distribution of
The specimens illustrated here were caught in the middle stretch (RPAR-M2) of the Paraná River, and the sample contained only a few females and two males.
This species, together with others of this genus, can be very abundant in small scale habitats, such as water pools, and is generally scarce in lotic environments. It was found at only three stations in the present study (Fig.
Geographical distribution of
The figured specimens were collected from the Iguaçu River at the reservoir of Foz do Areia (FARE-D) (Figure
Geographical distribution of
The specimens illustrated were collected from the lower Paraná River (RPAR-L2). This species appears to be widely distributed in the south of the basin, from the Iguaçu River into more temperate conditions (Fig.
Geographical distribution of
The illustrated specimens were collected from the lower Paraná River (RPAR-L2). The body length is slightly larger than the known range for males, 1315 to 1439 μm, given by
Geographical distribution of
Females of
The illustrated specimens were collected from the Parnaíba River at Emborcação Reservoir (Fig.
Geographical distribution of
The illustrated specimens were collected from the upper Tiete River, at the Barra Bonita Reservoir. In addition to the well-developed spinous process on segment 15 of A1R of the male,
Earlier studies (
Geographical distribution of
The specimens illustrated here were collected in the upper Paraguay River. This is the only calanoid species that was found throughout the Paraguay basin (Fig.
Geographical distribution of
This species has a wide distribution in rivers and associated systems like marginal ponds, but it is not typically recorded in reservoirs. This species is easily distinguishable by the position of the lateral spine on a lobe on the coxa of P5 and by the length of spinous processes on segments 13 and 15 of the male A1R. Some studies have reported this species under the name
We recommend a thorough comparative analysis of specimens of
The illustrated specimens were collected from the middle stretch of the Paraná River (Fig.
Geographical distribution of
The specimens depicted here were collected in Furnas Reservoir on the Grande River (Fig.
Geographical distribution of
Light micrograph comparing males of
In addition,
Recently,
Our specimens were taken in the Grande River at Furnas Reservoir. In the present study this species was found in southeastern and southern Brazil and in the upper part of the Paraná River basin, with its southerly distribution boundary represented by the Iguaçu River (Fig.
Geographical distribution of
This species was collected in the Machadinho Reservoir (MAC-U) on the Uruguay River and it can be easily identified by the unusual form of the caudal setae. It is distributed across the southern part of de la Plata river basin, including southern Brazil, south of the Iguaçu River (Fig.
Geographical distribution of
The specimens were collected in the middle section of the Paraná River at Yaciretá Reservoir (Fig.
Geographical distribution of
This species can be easily distinguished from its congeners by the proximal processes on the internal margin of the male right BspP5 and by the shape of the wings and GS of females. A comparison with the description by
The specimens examined were collected in the lower stretch of the Paraguay River (RPAG–B). This species is found in Argentina in the middle and lower stretches of the Paraná River and it can be considered to be a common species in the zooplankton community of this region (Fig.
Geographical distribution of
The illustrated specimens were caught in the upper reaches of the Uruguay River, in the Machadinho Reservoir. The northernmost boundary of its distribution may lie in the northern sector of Paraná State (Brazil), its northernmost record is from the floodplain of the upper Paraná River (Fig.
Geographical distribution of
This species has been the subject of much taxonomic confusion.
There are two other synonyms:
Further study of this species is necessary, including study of museum collections, in order to verify these synonymies and assess the evidence supporting the placement of this species in the genus
The specimens were collected in the low stretch of the Uruguay River at Salto Grande Reservoir (Fig.
Geographical distribution of
The genus
Several individuals of this species were found in the Yaciretá Reservoir (Fig.
Geographical distribution of
The specimens were found in the middle part of the Paraná River (Fig.
Geographical distribution of
Nineteen species of diaptomid copepods were found during the present survey, but this figure probably is markedly lower than the estimated total for de la Plata river basin. The reason for this discrepancy may be related to sample representativeness due to limitations in terms of seasonality and kind of sampled freshwater habitats (only large rivers and reservoirs). Historical records suggest that there are at least another 15 species to be found in the basin.
There was no gradual decrease in the number of species towards the south of the continent, as might be inferred from
With the exception of the most widespread species,
As emphasized in the diagnoses of species given above, the detailed analysis of segment 20 of the male A1R revealed substantial variation in the shape and state of development of the distal process of this segment: a falciform process is usually present but other shapes may occur, and many species lack a process on this segment. It is necessary to be cautious in interpreting the wide variability in this process exhibited by species of some diaptomid genera. Based on our observations, it should not be used alone or as a strict diagnostic character for the identity of a particular taxon.
In the genus
The fifth leg (P5) of adult diaptomids provides the main set of differential characteristics for most species. However, for some species of the
Body length is useful for the identification of some species of
We did not find
We decided to treat
P5 of male
As a result of previous faunistic surveys, some researchers have inferred that particular calanoid species have disappeared from the region (e.g.
Taxonomically, the identification of
All these data indicate that care must be taken when reporting the disappearance of a particular species from a habitat; this conclusion should be drawn only after failure to find the species after continued sampling over extended periods of time. The probability of a species being found again seems high when routine sampling is used (e.g.
Studies carried out in Europe and Asia over long time periods have demonstrated that particular species may be dominant at rare intervals over a 20 year time series.
Within de la Plata river basin, the results obtained in this study combined with our review of published data suggest the following recommendations for future research: 1. Continue studying sites where historical collections have been made; 2. Study large and productive reservoirs for which little information is available and where new species records are likely; 3. Conduct studies in places that are unexplored and represent gaps in information, including reservoirs, ponds and wetlands adjacent to tributaries of the Upper Paraguay River, Upper Parnaíba River, Upper Uruguay River and west of the state of Rio Grande do Sul, the region of “Esteros de Iberá” (in Argentina); and 4. Study the transition areas between the northern and southern faunas, in the rivers Iguaçu, Paraná (Yaciretá Reservoir) and middle/upper Uruguay, focusing on flood periods and correlations with bird migration routes.
There are several taxonomic problems still to be resolved within the Neotropical diaptomids and it would be useful to test whether
The following genera and species should be reviewed as their taxonomic status is currently equivocal:
The rarity and seasonallity of some species in the basin, such as
To FAPESP (2008/02015-7; 2009/00014-6; 2011/18358-3) for financial support. We are deeply grateful to Eduardo Suárez Morales (Mexico), Janet Bradford Grieve (Australia) and Silvina Menu Marque (Argentina) for their detailed revision of the text; to Juan C. Paggi (Argentina), Edinaldo Nelson dos Santos Silva (INPA, Manaus, Brazil), Janet W. Reid (USA), and Margarita Frutos (Argentina) for providing information, suggestions and for help in checking some identifications; to Maria L. Negreiros Fransozo (UNESP, Botucatu, Brazil) for lending optical equipment; and to Tiago Tardivo (CME-UNESP, Botucatu, Brazil) for help with the SEM photographs.