Three new species of the Eigenmannia trilineata species group (Gymnotiformes: Sternopygidae) from northwestern South America

Edgar Esteban Herrera-Collazos1, Aleidy M. Galindo-Cuervo1, Javier A. Maldonado-Ocampo1† and Melissa Rincón-Sandova1

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Abstract​


EN

Eigenmannia is one of the more taxonomically complex genera within the Gymnotiformes. Here we adopt an integrative taxonomic approach, combining osteology, COI gene sequences, and geometric morphometrics to describe three new species belonging to the E. trilineata species group from Colombian trans-Andean region. These new species increase the number of species in the E. trilineata complex to 18 and the number of species in the genus to 25. The distribution range of the E. trilineata species group is expanded to include parts of northwestern South America and southern Central America.

Keywords: Electric fishes; Glass knifefishes; Integrative taxonomy; Species delimitation; Trans-Andean region

ES

Eigenmannia es uno de los géneros taxonómicamente más complejos dentro de los Gymnotiformes. En este artículo adoptamos un enfoque taxonómico integrador, que combina osteología, secuencias del gene COI y morfometría geométrica, para describir tres nuevas especies que pertenecen al grupo de especies de E. trilineata de la región transandina de Colombia. Estas nuevas especies aumentan el número de especies en el complejo E. trilineata a 18 y el número de especies en el género a 25. El rango de distribución del grupo de especies de E. trilineata se ha expandido al noroeste de Sudamérica y el sur de América Central.

Palabras clave: Delimitación de especies; Peces eléctricos; Pez cuchillo de cristal; Región transandina; Taxonomía integradora

Introduction​


Eigenmannia Jordan, Evermann, 1896 is the most diverse genus in the neotropical electric fish family Sternopygidae, with 22 valid species (Dutra et al., 2014; Tab. S1 – available only in the online version). The genus occupies trans-Andean drainages of Panamá and northwestern South America and is widely distributed in cis-Andean drainages to as far south as northern Argentina (Albert, 2001). Eigenmannia is considered one of the most taxonomically confused genera in the order Gymnotiformes (Dutra, 2015), although phylogenetic relationships within Eigenmannia have received some recent attention (Tagliacollo et al., 2016; Peixoto, Ohara, 2019).

Peixoto et al. (2015) proposed an Eigenmannia trilineata López, Castello, 1966 species group comprising 15 species based on a single exclusive synapomorphy – the presence of a superior medial stripe on the flank. The E. trilineata species group has not previously been reported in trans-Andean basins (drainages along the Western slope of the Eastern cordillera that flow into both the Pacific and the Caribbean). However, three Eigenmannia species outside this species group are known from this region: E. humboldtii (Steindachner, 1878), E. meeki Dutra, Santana, Wosiacki, 2017, and E. virescens (Valenciennes, 1836) (e.g., Maldonado-Ocampo, Albert, 2003; Matamoros et al., 2015; Dutra et al., 2017). Recently, Peixoto et al. (2015) restricted E. virescens to forms without dark horizontal stripes from the Paraná river and de La Plata river basins. This range-restriction invalidates records of Eigenmannia ascribed to E. virescens from the Catatumbo, Ranchería, Magdalena, Sinú, Atrato, Tuira, and Bayano rivers (Albert, 2003; Albert, Crampton, 2006; Maldonado-Ocampo, 2011). Because all trans-Andean forms previously ascribed to E. virescens present a superior medial stripe on the flank, we instead propose that they belong to the Eigenmannia trilineata species group.

In this study, we adopted an integrative taxonomic approach (Schlick-Steiner et al., 2010) to reveal and describe three new species of Eigenmannia belonging to the E. trilineata species group from trans-Andean drainages of northwestern South America and southern Central America. We used data from osteology, morphometrics, and COI gene sequences for species delimitations, following a similar recent approach (Santana et al., 2019). These new species increase the number of Eigenmannia species to 26 (here E. goajira Schultz, 1949, which was assigned incertae sedis to the Eigenmanniinae, Dutra et al., 2014, is excluded from the species count) and the number of species in the E. trilineata species group to 18 (Dutra et al., 2014; Peixoto, Ohara, 2019). The three new species described herein also expand the range of distribution of the E. trilineata species into trans-Andean drainages of northwestern South America and parts of southern Central America.

Material and methods


Material examined. The analyses presented herein are restricted to specimens of the E. trilineata species group, unless stated otherwise. Specimens were examined from the collections of the Pontificia Universidad Javeriana (MPUJ), Universidad del Tolima (CZUT-IC), Instituto de Ciencias Naturales de la Universidad Nacional de Colombia (ICN-MHN), Instituto de Investigación de Recursos Biológicos Alexander von Humboldt (IAvH-P) and the Smithsonian Tropical Research Institute (STRI). Analyses were restricted toadult specimens (individuals exceeding 150.0 mm in total length, following Hopkins, 1974).

Geometric morphometrics. Photographs of the left flank were taken using a digital camera (Canon EOS REBEL T5i, lens: EF-S18-55.0 mm f/3.5-5.6 III) from a minimum of 20 individuals in different river basins (e.g., trans-Andean basins including Magdalena, Atrato, Cauca, Catatumbo, Caribe, and three cis-Andean basins; Tab. 1), belonging to recognized biogeographic units within northern South America (NSA) (Albert, Reis, 2011). We divided the Magdalena basin into three groups corresponding to its lower, middle, and upper course (see Tab. 1), given its large basin size.

TABLE 1 | Samples used in the current study for the geometric morphometric analysis. Cis-Andean drainages include the Orinoco, Amazon, Paraná, and other small and independent rivers in the Pampean and Patagonian regions of Argentina. Trans-Andean drainages include Magdalena, Atrato, Cauca, Caribe, and Catatumbo (see Fig. 7). The Magdalena basin was subdivided into three different sub-regions: upper (headwaters to Honda), middle (Honda to “El Banco”), and lower (“El Banco” to Bocas de Ceniza).

Basin

No. Individuals

Upper Magdalena

62

Lower Atrato

30

Lower Magdalena

81

Cauca – Nechi

30

Catatumbo – Maracaibo

81

Caribe – Guajira

30

Middle Magdalena

79

Cis-Andean

317

 

Both landmarks and semi-landmarks were used to assess morphological variation, following Bookstein (1991) and Zelditch et al. (2012). The landmarks were: (1) Tip of the snout; (2) Anterior naris; (3) Posterior naris; (4) Anterior edge of the eye; (5) Rear edge of the eye; (6) nape; (7) Posterior edge of operculum; (8) Upper edge of the gill opening; (9) Lower border of the gill opening; (10) Upper extremity of pectoral fin base; (11) Lower extremity of the base of the pectoral fin; (12) Anal-fin origin; (13) Anal opening; (14) Anterior lower jaw end; (15) Rear end of the lower jaw (Fig. 1).

FIGURE 1| Landmarks (red dots) and Semi-landmarks (points equally spaced over imaginary white lines).

Semi-landmarks followed the trajectory of three curves in the individual: (1) Dorsal head profile (15 semi-landmarks from landmark 1 to 6), (2) Gill opening (9 semi-landmarks from landmark 8 to 9), and (3) Ventral profile of the head (12 semi-landmarks from landmark 14 to 13), (Fig. 1). Type 1 landmarks (intersections of structures, curves, or center of structures) and type 2 landmarks (sections of maximum curvature) were positioned at the start and endpoints of commonly taken measurements on Gymnotiform fishes (Mago-Leccia, 1978; Hulen, 2005; Zelditch et al., 2012). Caudal landmarks were avoided due to variable degrees of caudal filament damage and/or regeneration, and due to post-fixation twisting of the posterior body portions of some specimens.

Subsequently errors were verified on the digitization of landmarks, for which a Principal Component Analysis (PCA) of 10 photos of the same individual in the IMP package (Sheets, 2004) was carried out. When no errors were found, a Generalized Procrustes Analysis (GPA) was performed, using the torsion energy method to define the sliding of the semi-landmarks. The centroid size (CS), the square root of the sum of the squared distances between the landmarks and the centroid configuration, were extracted to perform tests such as allometric analysis and homogeneity of allometric slopes.

After eliminating the allometric effects, a between-group PCA (BGPCA) was performed. This allowed the main components of morphological variation to be exported to tangent space, thus detecting the morphometric variation of the samples. A Randomized Residual Permutational Multivariate Analysis of Variance/Canonical Variate Analysis (PERMANOVA/CVA) was then carried out to detect the effect of the aggrupation in the morphometrical differences. Finally, a pairwise test between the least-squares means of each group was performed using the Goodall’s F-test, with 1000 bootstrap replicates.

All geometric morphometrics analyses were performed using TPS series software (Rohlf, 2016a,b), the R software version 3.4.0, was implemented using the following packages: GEOMORPH 3.0.6 (Adams, Otálora-Castillo, 2013; Adams et al., 2018), SHAPES 1.2.0 (Dryden, Mardia, 2016), and MULTIGROUP 0.4.4 (Eslami et al., 2015).

Morphometric measurements and meristic. Linear measurements were taken from the same individuals and groups used in geometric morphometrics, also from their left side. All measurements, counts, and notations follow Mago-Leccia (1978) and Albert (2001).

Osteology. River basins and individuals used for cleared and stained protocol were as follows: Upper Magdalena (1 specimen); Lower Magdalena-Cauca-San Jorge (2 specimens); Baudo (1 specimen); Caribe-Guajira (2 specimens); Catatumbo-Maracaibo (1 specimen); Cauca (1 specimen); Cesar (1 specimen); Lower Atrato (1 specimen). We used the Dingerkus, Uhler (1977) clearing and staining protocol with the following modifications: (1) Skin removed; (2) Preservation in 10% formalin for five days; (3) Dehydration successively in 50%, 70%, and 96% ethyl alcohol for 24 h; (4) Stain with Alcian blue solution (per 1000 mL: 600 mL absolute ethanol, 40 mL acetic acid, and approx. 3 mg Alcian blue) for two days; (5) Wash with tap water for five min; (6) Neutralize with saturated sodium borate for 24 h; (7) Clear muscles (850 mL of 1% potassium hydroxide and 150 mL of hydrogen peroxide) for three hours; (8) Wash with tap water for five min; (9) Digest muscle for approximately 30 to 60 days (650 mL of saturated sodium borate solution, 340 mL distilled water 65, 1 tablespoon of trypsin and 10 mL of H2O2); (10) Stain with Alizarin red (per 1000 mL: 1% KOH solution, 1 mg Alizarin red stain, until it appeared dark purple) for three days; (11) Distaining from alizarin red solution (350 mL saturated sodium borate solution, 650 mL distilled H2O, and 1 tablespoon of trypsin); the process took approximately 12 days and it was necessary to change the solution when it became dark, and (12) Preservation in glycerin plus 1% potassium hydroxide in a ratio of 1: 3, 2: 2, 3: 1, and 4: 0 respectively, depending on the time taken for the muscles to clear.

Each cleared and stained individual was examined and dissected using an Advanced Optical Huvitz HSZ-700 stereoscope. We focused our efforts on: (1) Skull (occipital region, otic and orbitotemporal region, ethmoid region and related dermal bones, paraphenoids and dermal bones); (2) Opercular apparatus, jaws and suspensorium (opercular apparatus, upper jaw, lower jaw, suspensorium); (3) Orbitals; (4) Branchial arches and hyoid arch; (5) Scapular waist and pectoral fin; (6) Spine, intermuscular bones, and anal fin. In all cases, both sides of each specimen were observed, following Raikow et al. (1990). For nomenclatural purposes, the osteological descriptions and diagnoses proposed by Mago-Leccia (1978) were followed.

DNA Extraction and Sequencing. For the use of the DNA Barcode (COI), muscle tissue samples were obtained from individuals from the basins listed in Tab. S2 (Tab. S2 – available only in the online version). The DNA extraction was performed using 20 mg of muscle tissue in the Qiagen BioSprint 96 extraction robot at the Smithsonian Tropical Research Institute (STRI). DNA was amplified using COI universal primers (Baldwin et al., 2009; COI Fish-BCL: 5’ TCAACYAATCAYAAAGATATYGGCAC3’, and COI Fish-BCH: 5’ ACTTCYGGGTGRCCRAARAATCA3’). For sequencing, the samples were sent to Macrogen. Additionally, COI sequences obtained by Maldonado-Ocampo (2011) and sequences deposited on both GenBank and BOLD assigned to E. virescens or Eigenmannia sp. collected on trans-Andean basins, were used in the analysis.

Sequence Analysis. Sequences were aligned using ClustalW in Bioedit v7.0.0 (Hall, 2011); a FASTA file was generated with all sequences. The substitution saturation was verified in DAMBE (Xia, Xie, 2001), and the result showed a value close to 1. The best nucleotide evolution model for the COI gene was specified via the Akaike Information Criterion using JmodelTest 2.1.7 (Darriba et al., 2012).

Species delimitation. The generalized mixed Yule coalescent (GMYC) analysis was used to delineate species using genetic data (Zhang et al., 2013), which is based on a prediction that leads to the appearance of distinct genetic clusters separated by longer internal branches (Pons et al., 2006; Fujisawa, Barraclough, 2013). To perform the GMYC analysis, BEAUti software was used to create the.xml file containing the features (e.g., partitions, sites, clocks, trees, MCMC) of the analysis carried out in BEAST v1.8.3 (Drummond, Rambaut, 2007) from the nucleotide alignment in Nexus format. A relaxed lognormal molecular clock tree was estimated with a birth-death model, which resulted in an ultrametric Bayesian tree based on the COI gene. The ESS values and the log files were evaluated in Tracer v1.6.0 (Rambaut et al.,2014). The maximum clade credibility tree was then obtained from the combined trials, after removing 20% of the trees in a “burn-in” in TreeAnnotator v1.8.2 (Rambaut, Drummond, 2016). Finally, the Newick tree was implemented in the splits 1.0 package (Fujisawa, Barraclough, 2013) in R, to obtain the threshold on the submitted tree (GMYC; Fujisawa, Barraclough, 2013). Second, the ABGD model, where the Barcode gap is used as a threshold to delimit species (Puillandre et al., 2012). Sequence alignments were loaded onto the ABGD website at http://wwwabi.snv.jussieu.fr/public/abgd/abgdweb.html and executed with the default settings (Pmin = 0.001, Pmax = 0.1, Steps = 10, X (relative gap width) = 1.5, Nb bins = 20), with the Kimura model (K80) selected for distance. Finally, only the main partitions obtained through the model were utilized. Lastly, genetic distances were calculated based on the Kimura 2-Parameter (K2P) nucleotide substitution model using the program MEGA 7 (Kumar et al., 2016).

Results​


Geometric Morphometrics. A total of 710 individuals were utilized for photographs and procedures. Individuals were organized into eight different groups corresponding to eight drainage basins (Tab. 1). A cis-Andean group comprising individuals belonging to Amazonas, Orinoco, and Paraná basins was included for comparison.PERMANOVA/CVA showed a highly significant (p<0.001) effect of size on the shape, thus demonstrating the expected allometric effect on the data (Tab. 2).

TABLE 2 | Allometric PERMANOVA testing for the effect of size on shape. Df: Degrees of freedom; SS: sum of squares; MS: mean sum of squares; R2: coefficient of determination; F: F value; Z: standard score; Pr(>F): p-value associated with the F statistic.

 

Df

SS

MS

R2

F

Z

Pr(>F)

log(size)

1

0.09

0.09

0.026

21.28

16.21

1.0E-04

Group

7

0.42

0.06

0.118

13.89

12.04

1.0E-04

Residuals

702

3.04

0.00

 

 

 

 

Total

710

3.55

 

 

 

 

 

 

After detecting the allometric effect on the data, it was necessary to verify if the individuals within each of the groups defined for this analysis had similar or different allometric slopes, accounting for different allometric effects within each group. The homogeneity of slopes test revealed that the null hypothesis of homogenous (i.e., parallel) slopes, among groups, was accepted (Tab. 3), thus avoiding the need to correct allometry differentially for each group and instead of complete allometric correction of the full dataset (Fig. 2). Size-adjusted residuals and allometry-free shapes were obtained as the allometric-corrected data. A re-run of the PERMANOVA/CVA no longer showed a significant effect of size on shape (Tab. 4).

FIGURE 2| Different group slopes. AT: Atrato; CAT: Catatumbo-Maracaibo; CG: Caribe-Guajira; CIS: cis-Andean; LM: Lower Magdalena; MM: Middle Magdalena; UM: Upper Magdalena.

TABLE 3 | Homogeneity of slopes test. Df: Degrees of freedom; SSE: error sum of squares; SS: sum of squares; R 2: coefficient of determination; F: F value; Z: standard score; Pr(>F): p-value associated with the F statistic.

 

Df

SSE

SS

R2

F

Z

Pr(>F)

Common Allometry

702

3.04

 

 

 

 

 

Group Allometries

695

2.94

0.09

0.026

3.191

0

1

 

TABLE 4 | PERMANOVA over size-adjusted residuals and allometry-free shapes for group effect. Df: Degrees of freedom; SS: sum of squares; MS: mean sum of squares; R2: coefficient of determination; F: F value; Z: standard score; Pr(>F): p-value associated with the F statistic.

 

Df

SS

MS

R2

F

Z

Pr(>F)

log(size)

1

0.00

0.00

0.00

0.08

0.06

1

Group

7

0.41

0.06

0.12

13.7

11.89

1.0E-04

Residuals

702

3.04

0.00

 

 

 

 

Total

710

3.46

 

 

 

 

 

 

The first BGPC accounted for 75.7% of the total shape variation in the dataset, while the second BGPC accounted for only 7.37% of total shape variation (Tab. 5). The high variation represented by the BGPC1 was mainly influenced by the length differences found at the anal-fin origin relative to the snout tip and the opercular opening. These observations suggest that the position of the anal-fin origin has taxonomic importance – especially in discriminating trans-Andean from cis-Andean taxa (yellow in Fig. 3); the origin of the anal fin appears much closer to the opercular opening (almost under it) in the cis-Andean taxa than in trans-Andean taxa (Fig. 3). The second BGPC is much more conservative about changes along the fish body. Maximum values on the BGPC2 correspond to a broader cephalic region and a distant position of the lower operculum relative to the mouth area (Fig. 3).

FIGURE 3| BG-PCA scatter plot for Eigenmannia. Red: Atrato; Fuchsia: Caribe-Guajira; Aqua: Catatumbo-Maracaibo; Yellow: cis-Andean; Green: Lower Magdalena; Gray: Middle Magdalena; Black: Upper Magdalena.

TABLE 5 | Between-group Principal Components values.

BGPC

Eigenvalue

% variance

accumulative

1

0.001

74.75

74.75

2

0.0001

7.37

82.12

3

9.29E-05

6.80

88.93

4

6.46E-05

4.72

93.66

5

5.23E-05

3.83

97.49

6

2.18E-05

1.59

99.08

7

1.24E-05

0.91

99.99

 

The PERMANOVA/CVA showed six significantly different canonical variates (CVs), the first two of which account for 64% of total variation. CV1 accounts for 39% of the complete variation (Wilk’s Lambda = 0.0256; ChiSquared = 2407.6252; df = 686; p<2.22045e-16) while CV2 accounts for 24% (Wilk’s Lambda = 0.0820; ChiSquared = 1642.7824; df = 582; p<2.22045e-16) (Tab. 6; Fig. 4).

FIGURE 4| MANOVA/CVA scatter plot. Red: Atrato; Fuchsia: Caribe-Guajira; Aqua: Catatumbo-Maracaibo; Yellow: cis-Andean; Green: Lower Magdalena; Gray: Middle Magdalena; Black: Upper Magdalena.

TABLE 6 | PERMANOVA/CVA Eigenvalues and variance.

CV

Eigenvalue

% variance

accumulative

1

2.2032

39.41

39.41

2

1.3832

24.71

64.12

3

7.50E-01

13.42

77.54

4

4.64E-01

8.29

85.83

 

PERMANOVA/CVA for differences between groups showed highly significant differences between almost every pair of groups, except for between Upper Magdalena and Atrato, where the differences were not shown to be significant, indicating morphological similarity (Tab. 7). All the trans-Andean groups (Upper Magdalena, Atrato, Lower Magdalena, Cauca-Nechi, Catatumbo-Maracaibo, Caribe-Guajira, and Middle Magdalena) were statistically different from the cis-Andean group, with every pairwise permutation p-value for morphometric differences being highly significant (Tab. 7).

TABLE 7 | Above diagonal Procrustes distances. Below diagonal pairwise permutation test p-values, not significant in bold-italics. UM: Upper Magdalena; AT: Atrato; LM: Lower Magdalena; CAT: Catatumbo-Maracaibo; CG: Caribe-Guajira; CIS: cis-Andean; MM: Middle Magdalena.

 

UM

AT

LM

CAT

CG

CIS

MM

UM

0.03

0.05

0.03

0.03

0.03

0.03

AT

0.2

0.05

0.03

0.04

0.03

0.03

LM

0.01

0.01

0.05

0.05

0.05

0.05

CAT

0.01

0.01

0.01

0.03

0.03

0.03

CG

0.01

0.01

0.01

0.01

0.03

0.03

CIS

0.01

0.01

0.01

0.01

0.01

0.03

MM

0.01

0.01

0.01

0.01

0.01

0.01

 

Species Delimitation. Genetic distances between the GMYC-derived groups were in all cases higher than 2% except for the difference between the Catatumbo group and the Maracaibo group, where the genetic distance was lower. The genetic distances between ABGD-derived groups were in all cases higher than 2%, in some cases reaching up to 14%. The ABGD analysis found a single group uniting Catatumbo and Maracaibo specimens. Additionally, genetic distances inferred with the K2P also support the results obtained with the other approximations (Tab. S3 – available only in the online version). Taking into account genetic distances, GMYC results, and ABGD results, we recognize four lineages, which are geographically delimited as follows (Fig. 5):

– Eigenmannia sp. (Upper Atrato)

– Eigenmannia camposi n. sp. (Lower Atrato, Cauca, Upper Magdalena, Middle Magdalena)

– Eigenmannia magoi n. sp. (Catatumbo, Maracaibo)

– Eigenmannia zenuensis n. sp.(Lower Magdalena-Cauca-San Jorge)

FIGURE 5| Bayesian phylogenetic tree of trans-Andean Eigenmannia obtained with COI data showing colored bars for GMYC (pink), ABGD (green), Genetic Distances (yellow), and numbers over final OTUs (blue). Cis-Andean Eigenmannia sp. specimens belong to Amazon and Orinoco basins.

Taxonomy. Based on the evidence described above, four new species for the trans-Andean region are proposed for the genus Eigenmannia, three of which are described below. All four species belong unambiguously to the Eigenmannia trilineata species group defined by Peixoto et al. (2015) because they all present the character of a superior medial stripe on the flank between the lateral line and the anal-fin base stripe. The fourth species, from the upper Atrato river basin, will be described in a subsequent publication.

Eigenmannia camposi, new species

urn:lsid:zoobank.org:act:B6260289-C9DC-4043-8B1F-657276087AFD

(Figs. 6-7; Tab. 8)

Holotype. IAvH-P 9238, 137.0 mm LEA, (COI: GenBank MN832888), Colombia, Tolima, Honda, Magdalena river, Upper Magdalena basin, 5°12’05.56” N 74°43’56.63” W, J. A. Maldonado-Ocampo, W. G. R. Crampton & N. Lovejoy.

Paratypes. IAvH-P 7819, 17, 119.0-154.0 mm LEA, Colombia, Tolima, Honda, Magdalena river, Upper Magdalena basin, 5°12’05.56”N 74°43’56.63”W, W. G. R. Crampton. IAvH-P 7820, 5 + 1c&s, 123.0-148.0 mm LEA, Colombia, Tolima, Honda, Magdalena river, Upper Magdalena basin, 5°12’05.56”N 74°43’56.63”W, W. G. R. Crampton. IAvH-P 7821, 5, 130.0-145.0 mm LEA, Colombia, Tolima, Honda, Magdalena river, Upper Magdalena basin, 5°12’05.56”N 74°43’56.63”W, W. G. R. Crampton.

FIGURE 6| Holotype IAvH-P 9238 for Eigenmannia camposi, scale bar 1 cm.

Non-types. CZUT-IC 1330, 2, 15.0-18.0 mm LEA, Colombia, Tolima, Cunday river, Upper Magdalena basin, 3°54’21.99”N 74°44’40.02”W. CZUT-IC 2331, 1, 14.0 mm LEA, Colombia, Tolima, La hoya gully, Upper Magdalena basin, 4°50’42.99”N 74°48’32.00”W. IAvH-P 9239, 1, 12.5.0 mm LEA, Colombia, Tolima, Magdalena river, Upper Magdalena basin, 5°12’05.56”N 74°43’56.63”W, William G. R Crampton. ICN-MHN 2702, 1, 13.0 mm LEA, Colombia, Boyacá, Las Quinchas mountain range, La Colorada gully, Middle Magdalena basin, 05°50’40.54”N 74°20’38.87”W, José I. Mojíca. ICN-MHN 3589, 1, 14.1 mm LEA, Colombia, Tolima, Guamo river, Upper Magdalena basin, 5°04’09.09”N 74°53’23.88”W, A. Roa, E. F. Prieto & M. Santos. ICN-MHN 3783, 1, 12.5 mm LEA, Colombia, Tolima, Magdalena system, Cuamo river, Upper Magdalena basin, 5°11’30.53”N 74°54’42.05”W, M. Santos. ICN-MHN 18487, 7, 7.5-14.7 mm LEA, Colombia, Cesar, Magdalena system, Simaña river basin, El Carmen gully, Middle Magdalena basin, 8°38’51.11”N 73°37’30.70”W, Corpobiotica. IAvH-P 7818, 8, 11.4-14.0 mm LEA, Colombia, Tolima, Magdalena river, Upper Magdalena basin, 5°12’05.56”N 74°43’56.63”W, W. G. R. Crampton. CZUT-IC 97, 1, 8.3 mm LEA, Colombia, Tolima, Potrerilla gully, Upper Magdalena basin, 4°16’58.00”N 75°01’54.01”W. CZUT-IC 987, 1, 11.7.0 mm LEA, Colombia, Tolima, Anchique river, Upper Magdalena basin, 3°34’35.00”N 75°07’13.00”W. CZUT-IC 1332, 1, 11.6 mm LEA, Colombia, Tolima, Bernal gully, Upper Magdalena basin, 5°12’12.99”N 74°46’56.99”W. CZUT-IC 11567, 6, 4.4-16.8 mm LEA, Colombia, Tolima, Anchique river delta, Upper Magdalena basin, 3°35’34.00”N 75°04’59.45”W, C. Conde. CZUT-IC 11606, 3, 7.2-10.8 mm LEA, Colombia, Tolima, Batatas gully, Upper Magdalena basin, 4°00’30.99”N 74°50’31.99”W, C. Conde. ICN-MHN 3251, 1, 11.2 mm LEA, Colombia, Boyacá, Las Quinchas mountain range, Puerto Romero, Middle Magdalena basin, 5°50’09.80”N 74°20’20.88”W, J. I. Mojíca. ICN-MHN 7061, 1, 12.4 mm LEA, Colombia, Caldas, Norcasia. Manso river, Remolinos zone, Middle Magdalena basin, 5°40’00.01”N 74°46’00.01”W, J. I. Mojíca. CZUT-IC 11672, 1, 9.9 mm LEA, Colombia, Antioquia, branch of León river towards Suriqui river, Atrato, Darién basin, 7°50’38.00 N 76°50’05.99”W, F. Villa. CZUT-IC 11648, 2, 4.4-5.5 mm LEA, Colombia, Antioquia, León river, confluence with Tumaradocito creek, Atrato, Darién basin, 7°40’03.00”N 76°58’10.99”W, F. Villa.

Diagnosis. Eigenmannia camposi can be distinguished from its congeners of the E. trilineata species group, except E. besouro Peixoto, Wosiacki, 2016 by the number of premaxillary teeth: 27 in 3-4 rows (vs. 8-10 in 2 rows in E. muirapinima Peixoto, Dutra, Wosiacki, 2015; 8-12 in 2 rows in E. antonioi Peixoto, Dutra, Wosiacki, 2015; 9-10 in 2 rows in E. guairaca Peixoto, Dutra, Wosiacki, 2015; 11-15 in 3 rows in E. loretana Waltz, Albert, 2018; 13-16 in 3 rows in E. pavulagem Peixoto, Dutra, Wosiacki, 2015; 16 in 3 rows in E. microstomus Reinhardt, 1852; 17 in 3 rows in E. sayona Peixoto, Waltz, 2017; 17-20 in 3 rows in E. correntes Campos-da-Paz, Queiroz, 2017; 22-24 in 4 rows in E. matintapereira Peixoto, Dutra, Wosiacki, 2015; 24-25 in 4 rows in E. desantanai Peixoto, Dutra, Wosiacki, 2015; 25-26 in 4 rows in E. vicentespelaea Triques, 1996; 31-33 in 4 rows in E. trilineata; 31-34 in 4-5 rows in E. zenuensis; 32 in 4 rows in E. magoi and 35-40 in 5 rows in E. waiwai Peixoto, Dutra, Wosiacki, 2015); it can further be distinguished from E. besouro by the number of simple pectoral rays: ii-iii (vs. ii in E. besouro) and by its larger suborbital depth: 30-37.7% HL (vs.18.3-24.8% HL in E. besouro).

Description. Morphometric and meristic data is shown in Tab. 8. Total Length (mm): 157.0-220.8 mm. Ovoid scapular foramen. 68-79 vertebrae. 13 precaudal vertebrae. 27 premaxillary teeth in 3-4 rows. 9-10 endopterygoid teeth in 1-2 rows. 20-22 teeth in dentary in 2 rows. Parietal and frontal bones articulated by synchondrosis by means of the frontoparietal suture (in this case the character is noteworthy the edges of the bones where they articulate have deep endings of variable size, but with a length greater than the teeth). Four or more foramina on the opercular opening of the frontal bone. Posterior-most arm of the lateral ethmoid bone elongated; articulates with the most anterior prolongation of the frontal bone forming a window. Width of anterior region of parasphenoid bone equal to width of two premaxillaries. Parasphenoid compressed towards posterior region (giving appearance of a glass bottle). Branchiostegal rays 5 in total, 4 is the largest. Urohyal, laminar and convex until middle par (from here it forms the urohial process, which extends to end of urohyal) Operculum upper edge rounded, bottom edge slightly extended. Endopterygoid with long ascendant process. Basihyal length ca. 1/2 of length of first ceratobranchial, slightly wider in anterior region, almost rectangular. Five ceratobranchials with width conserved. Five basibranchials of which 2-3 are well ossified. Four hypobranchials, first 3 well ossified. Tooth plate of the upper pharyngeal with 7 teeth. Tooth plate of the lower pharyngeal with 12 teeth. 10 cartilaginous gill rakers.

TABLE 8 | Measurements and counts for Eigenmannia camposi, new species. Min: minimum; Max: maximum; SD: standard deviation; N: number of specimens measured.

 

Holotype

Min

Max

Mean

SD

N

Total Length (mm)

181.0

157.0

220.9

178.3

43

Length to end of anal fin (mm)

137.0

122.0

177.9

138.4

43

Head Length (mm)

17.2

12.5

21.1

18.2

43

 

Percentage of LEA

Head length

12.5

8.5

15.7

13.2

0.0

43

Preanal distance

15.4

10.5

20.0

16.3

0.0

43

Prepectoral distance

13.2

8.4

16.5

13.4

0.0

43

Snout to anus

8.5

5.8

11.2

9.1

0.0

43

Maximum body depth

13.3

8.9

17.0

13.5

0.0

43

Anal-fin length

84.7

69.1

88.4

83.8

0.0

43

Pectoral-fin width

2.0

1.2

2.7

2.0

0.0

43

Caudal filament length

32.1

10.1

37.7

28.9

0.1

43

 

Percentage of HL

Snout length

25.4

20.0

42.9

26.9

0.1

43

Pre nape distance

85.0

67.9

85.2

75.2

0.0

43

Snout to posterior naris distance

21.1

14.9

24.7

19.0

0.0

43

Posterior naris to orbit distance

10.0

5.6

26.6

12.1

0.1

43

Internarial width

12.2

9.3

18.1

11.6

0.0

43

Orbital diameter

18.2

14.1

21.1

17.0

0.0

43

Postorbital distance

60.5

55.6

77.5

63.1

0.1

43

Opercular opening

27.4

23.2

31.6

27.5

0.0

43

Interorbital distance

32.0

25.5

56.3

35.2

0.1

15

Oral width

17.6

15.3

25.7

19.5

0.0

43

 

Counts

Anal-fin rays

175

173

217

 

 

38

Simple pectoral-fin rays

2

2

3

 

 

43

Ramified pectoral-fin rays

14

12

14

 

 

43

Scales over lateral line

164

115

173

 

 

38

Scales above lateral line

7

5

8

 

 

38

 

Coloration in alcohol. Background color pale yellow to dark orange. Head brown/dark dorsally and rapidly becoming lighter through the snout. Lips and suborbital region with brown chromatophores slightly darkening the area. Body with four visible dark horizontal stripes: (1) Lateral-line stripe narrow and dark, one scale deep, from the first perforated scale to the caudal filament; (2) Superior medial stripe wide, formed by often scattered spots, extending from the mid-portion of the gas bladder to approximately half of the anal fin; (3) Inferior medial stripe dark and wide, almost two scales deep, well colored and darker in region of the caudal filament, generally starting near the anus and continuing until the end of the anal fin; (4) Stripe along anal-fin base dark, one and a half scales deep, extending along the base of the anal fin. Pectoral fin with scattered dark chromatophores generally near the base and anal fin hyaline. Dark humeral spot marking the beginning of the lateral-line stripe. Nape dark.

Geographic distribution. Eigenmanniacamposi is known from the lower Atrato basin, and in the upper and middle Magdalena and Cauca river basins in Colombia (Fig. 7).

Etymology. The specific epithet “camposi” is assigned to the new species in honor of Dr. Ricardo Campos-da-Paz for his contributions to our knowledge of gymnotiform fishes.

FIGURE 7| Map illustrating the known geographic distribution of Eigenmannia camposi (circles), E. zenuensis (squares), and E. magoi (triangles). Red symbols indicate type localities.

Eigenmannia magoi, new species

urn:lsid:zoobank.org:act:29463771-B47A-4C39-AD8D-352C85CE0E6B

(Figs. 7-8; Tab. 9)

Holotype. ICN-MHN 2318, 1, 13.1 mm LEA, (COI: GenBank MN200122), Colombia, Norte de Santander, La Gabarra, Catatumbo river, Catatumbo basin, 8°59’55.28”N 72°54’08.64”W, J. I. Mojica & M. Camargo.

Paratypes. IAvH-P 15913, 19-20.5, 1c&s, 171.4 mm LE, Colombia, Norte de Santander, Zulia river, Agualasal gully, Catatumbo Basin, 8°13’24.89”N 72°32’00.70”W, Carlos DoNascimiento, J. G. Albornoz-Garzón & M. H. Sabaj. IAvH-P 11768, 25, 81.0-141.0 mm LEA, Colombia, Norte de Santander, La Gabarra, Catatumbo river, Catatumbo basin, 8°59’55.28”N 72°54’08.64”W, A. Ortega-Lara. ICN-MHN 2383, 1 c&s, (COI: GenBank MN200109) 17.5 mm LE, Colombia, Norte de Santander, La Gabarra, Tigre creek, Catatumbo basin, 9°01’00.98”N 72°51’57.52”W, G. Gálvis & M. Camargo.

Non-types. CZUT EV_T63, 12, 8.6-16.7 mm LEA, Colombia, Norte de Santander, Agualasal gully, Catatumbo basin, 8°13’05.00”N 72°32’31.20”W.

FIGURE 8| Holotype ICN-MHN 2318 for Eigenmannia magoi, scale bar 1 cm.

TABLE 9 | Measurements and counts for Eigenmannia magoi, new species. Min = minimum; Max = maximum; SD = standard deviation; N = number of specimens measured.

 

Holotype

Min

Max

Mean

SD

N

Total Length (mm)

172.0

158.0

299.0

211.7

30

Length to end of anal fin (mm)

131.0

81.0

255.0

128.4

30

Head Length (mm)

17.2

13.0

20.0

16.3

30

 

Percentage of LEA

Head length

18.2

7.0

24.0

13.6

0.0

30

Preanal distance

18.7

9.0

28.0

16.3

0.1

30

Prepectoral distance

13.3

7.0

23.0

13.6

0.0

30

Snout to anus

9.2

5.0

17.0

9.4

0.0

30

Maximum body depth

16.1

7.0

22.0

13.9

0.0

30

Anal-fin length

81.7

61.0

100.0

83.8

0.1

30

Pectoral-fin width

1.6

1.0

3.0

1.9

0.0

30

Caudal filament length

31.3

13.0

48.0

32.6

0.1

30

 

Percentage of HL

Snout length

21.6

20.0

29.0

24.4

0.0

30.0

Pre nape distance

74.6

66.0

83.0

73.0

0.0

30

Snout to posterior naris distance

18.1

16.0

22.0

19.2

0.0

30

Posterior naris to orbit distance

10.0

8.0

15.0

10.5

0.0

30

Internarial width

12.6

9.0

16.0

12.1

0.0

30

Orbital diameter

15.3

15.0

21.0

17.8

0.0

30

Postorbital distance

65.6

55.0

66.0

60.1

0.0

30

Opercular opening

28.7

22.0

34.0

27.1

0.0

30

Interorbital distance

31.2

28.0

47.0

36.3

0.1

8

Oral width

17.7

16.0

21.0

18.9

0.0

30

 

Counts

Anal-fin rays

210

182

259

 

 

30

Simple pectoral-fin rays

3

2

4

 

 

30

Ramified pectoral-fin rays

12

11

14

 

 

30

Scales over lateral line

151

142

274

 

 

30

Scales above lateral line

7

6

18

 

 

30

 

Diagnosis. Eigenmannia magoi can be distinguished from its congeners of the E. trilineata species group, except E. trilineata and E. zenuensis by the number of premaxillary teeth: 32 in 4 rows (vs. 8-10 in 2 rows in E. muirapinima; 8-12 in 2 rows in E. antonioi; 9-10 in 2 rows in E. guairaca; 11-15 in 3 rows in E. loretana; 13-16 in 3 rows in E. pavulagem; 16 in 3 rows in E. microstomus; 17 in 3 rows in E. sayona; 17-20 in 3 rows in E. correntes; 18-29 in 3-4 rows in E. besouro; 22-24 in 4 rows in E. matintapereira; 24-25 in 4 rows in E. desantanai; 25-26 in 4 rows in E. vicentespelaea; 27 in 3-4 rows in E. camposi and 35-40 in 5 rows in E. waiwai); it can further be distinguished from E. trilineata and E. zenuensis by the number of teeth in the dentary: 35-39 in 2-3 rows (vs. 23 in 2 rows in E. trilineata and 56-60 in 4-5 rows in E. zenuensis); finally it can further be distinguished from E. zenuensis by the shape of the vomer with extensions separated at the posterior end (vs. vomer extensions forming an inverted ridge in E. zenuensis) and by the lower number of teeth in the upper pharyngeal plate 5-6 (vs. 7 in E. zenuensis).

Description. Morphometric and meristic data is presented in Tab. 10. Total Length (mm): 158.0-298.9. Ovoid scapular foramen. 74 vertebrae; 14 precaudal vertebrae. 32 premaxillary teeth in 4 rows. 11 endopterygoid teeth in 2 rows. 35-39 teeth in dentary in 2-3 rows. Suture between parietal and frontal bones serrated with variable teeth size. Three or more foramina on the opercular opening of the frontal bone. Posterior-most arm of the lateral ethmoid bone elongated, articulates with anterior-most prolongation of frontal bone forming window. Orbitosphenoid bone wide. Pterosphenoid bone wide. Posterior edge of pterotic bone not rounded, instead oval and extended. Branchiostegal rays 5 in total, 1-2 of similar length, 3-5 with wide extensions, branchiosteal 4 the largest. Operculum upper edge rounded. Endopterygoid with long ascendant process. Basihyal length approximately 1/2 of length of first ceratobranchial, slightly wider in anterior region, almost rectangular. In all ceratobranchials width is conserved. 4 basibranchials, 1-2 well ossified, 3 lightly ossified. Four hypobranchials, first 3 well ossified. Tooth plate of the upper pharyngeal with 5-6 teeth. Tooth of the lower pharyngeal plate with 12 teeth. 10 cartilaginous gill rakers.

TABLE 10 | Measurements and counts for Eigenmannia zenuensis, new species. Min = minimum; Max = maximum; SD = standard deviation; N = number of specimens measured.

 

Holotype

Min

Max

Mean

SD

N

Total Length (mm)

153.6

151.0

237.0

191.9

53

Length to end of anal fin (mm)

127.2

102.0

196.0

148.3

53

Head Length (mm)

17.9

12.0

24.0

18.7

53

 

Percentage of LEA

Head length

13.7

9.0

18.0

12.8

0.0

53

Preanal distance

16.1

12.0

28.0

18.3

0.0

53

Prepectoral distance

12.7

8.8

19.6

12.9

0.0

53

Snout to anus

8.4

6.2

14.0

9.2

0.0

53

Maximum body depth

13.2

8.9

22.9

15.4

0.0

53

Anal-fin length

78.5

63.6

87.4

80.4

0.1

53

Pectoral-fin width

2.2

1.0

3.4

1.9

0.0

53

Caudal filament length

20.8

6.9

49.0

29.7

0.1

53

 

Percentage of HL

Snout length

23.4

18.2

25.9

22.2

0.0

53

Pre nape distance

65.7

63.9

77.4

70.7

0.0

53

Snout to posterior naris distance

16.0

15.8

24.1

18.9

0.0

53

Posterior naris to orbit distance

11.1

5.5

11.2

8.5

0.0

53

Internarial width

10.5

8.4

15.9

12.6

0.0