A new species of <i>Pimelodella</i> (Siluriformes: Heptapteridae) from the Paraguai basin, Brazil, with a discussion regarding its distribution

A new species of Pimelodella is described from the rio Paraguai basin in Mato Grosso do Sul and Mato Grosso States, Brazil. The new species distinguishes from all other members of the genus based on a unique combination of characteristics, which include: dorsal profile straight from snout to dorsal-fin, maxillary barbel reaching at least the anal-fin terminus when parallel to main body axis, robust dorsal-fin spine bearing small spinules along three-fourths of its posterior margin, 41–42 total vertebrae (rarely 43 or 44), 13–23 large and retrorse blades at the posterior margin of the pectoral-fin spine, and dorsolateral region of body slightly darkened. This study also discusses the ichthyofaunal similarities between the Paraguai and Amazon basins, shedding light on their biogeographic history. Additionally, the research includes considerations about the sexual dimorphism of Pimelodella and provides an identification key for the Pimelodella species found in the Paraguai basin.

Keywords:
Biogeography; Catfishes; Identification key; Sexual dimorphism; Taxonomy

Authorship

Veida Pierre

Conceptualization

Data curation

Formal analysis

Funding acquisition

Investigation

Methodology

Project administration

Resources

Visualization

Writing-original draft

Writing-review and editing

Programa de Pós-Graduação em Zoologia – UnB, Laboratório de Ictiologia Sistemática, Instituto de Ciências Biológicas, Universidade de Brasília, Campus Universitário Darcy Ribeiro, 70910-900 Brasília, DF, Brazil. (VP) veidampierre@gmail.com, (VS) vslobodian@unb.br (corresponding author).Universidade de BrasíliaBrazilBrasília, DF, BrazilPrograma de Pós-Graduação em Zoologia – UnB, Laboratório de Ictiologia Sistemática, Instituto de Ciências Biológicas, Universidade de Brasília, Campus Universitário Darcy Ribeiro, 70910-900 Brasília, DF, Brazil. (VP) veidampierre@gmail.com, (VS) vslobodian@unb.br (corresponding author).

http://orcid.org/0000-0002-7131-7537

Veronica Slobodian

Conceptualization

Data curation

Formal analysis

Funding acquisition

Investigation

Methodology

Project administration

Resources

Supervision

Visualization

Writing-original draft

Writing-review and editing

http://orcid.org/0000-0002-4754-5871

Edited-by

Carlos DoNascimiento

Correspondence

Veronica Slobodian vslobodian@unb.br

Competing Interests

The author declares no competing interests.

Ethical Statement

Since we only utilized specimens from scientific collections, no collection permits were required.

SCIMAGO INSTITUTIONS RANKINGS

Figures | Tables

Figures (5)
Tables (1)

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FIGURE 1 |
Pimelodella guato, holotype, ZUFMS-PIS 8515, 78.5 mm SL, Brazil, Mato Grosso do Sul, Corumbá municipality, rio Paraguai basin, rio Miranda, sandy beaches at Passo do Lontra region, 19°34’37”S 57°00’42”W. A. Dorsal; B. Left lateral; and C. Ventral views. Scale bar = 1 cm.

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FIGURE 2 |
Left lateral view of radiographs of Pimelodella species, illustrating the dorsal lamina of Weberian complex vertebrae of A.Pimelodella guato, paratype, ZUFMS-PIS 647, 90.1 mm SL; B.P. taeniophora, ZUFMS-PIS 6320, 68.9 mm SL; C.P. mucosa, holotype, CAS 63720, 97.4 mm SL; and D.P. serrata, LIRP 10022, 83.6 mm SL.

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FIGURE 3 |
Pectoral-fin spine of A.Pimelodella guato, paratype, CIUnB 1772, 91.2 mm SL, length of spine 16.7 mm; B.P. taeniophora, ZUFMS-PIS 6320, 68.9 mm SL, length of spine 11.4 mm; C.P. mucosa, holotype, CAS 63720, 97.4 mm SL, length of spine 22.8 mm; D.P. serrata, holotype, FMNH 57979, 55.7 mm SL, length of spine 18.3 mm; and E.P. howesi, holotype, ANSP 69036, 79.3 mm SL, length of spine 17.8 mm.

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FIGURE 4 |
Geographic distribution of Pimelodella guato in the rio Paraguai basin (red star, type-locality; red dots, paratype localities). The symbols might represent more than one voucher specimen each.

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FIGURE 5 |
Sexually dimorphic traitsin an adult male specimen ofPimelodella guato (paratype, CIUnB 1772, 93.8 mm SL). A. Filament on the non-spinous portion of dorsal-fin second (unbranched) ray, indicated by a white arrow; and B. Enlarged urogenital papilla, indicated by a white arrow. Scale bars = 1 cm.

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TABLE 1 |
Morphometric data for the holotype and 42 paratypes of Pimelodella guato. N = number of specimens; SD = Standard deviation.

FIGURE 1 | Pimelodella guato, holotype, ZUFMS-PIS 8515, 78.5 mm SL, Brazil, Mato Grosso do Sul, Corumbá municipality, rio Paraguai basin, rio Miranda, sandy beaches at Passo do Lontra region, 19°34’37”S 57°00’42”W. A. Dorsal; B. Left lateral; and C. Ventral views. Scale bar = 1 cm.

FIGURE 2 | Left lateral view of radiographs of Pimelodella species, illustrating the dorsal lamina of Weberian complex vertebrae of A.Pimelodella guato, paratype, ZUFMS-PIS 647, 90.1 mm SL; B.P. taeniophora, ZUFMS-PIS 6320, 68.9 mm SL; C.P. mucosa, holotype, CAS 63720, 97.4 mm SL; and D.P. serrata, LIRP 10022, 83.6 mm SL.

FIGURE 3 | Pectoral-fin spine of A.Pimelodella guato, paratype, CIUnB 1772, 91.2 mm SL, length of spine 16.7 mm; B.P. taeniophora, ZUFMS-PIS 6320, 68.9 mm SL, length of spine 11.4 mm; C.P. mucosa, holotype, CAS 63720, 97.4 mm SL, length of spine 22.8 mm; D.P. serrata, holotype, FMNH 57979, 55.7 mm SL, length of spine 18.3 mm; and E.P. howesi, holotype, ANSP 69036, 79.3 mm SL, length of spine 17.8 mm.

FIGURE 4 | Geographic distribution of Pimelodella guato in the rio Paraguai basin (red star, type-locality; red dots, paratype localities). The symbols might represent more than one voucher specimen each.

FIGURE 5 | Sexually dimorphic traitsin an adult male specimen ofPimelodella guato (paratype, CIUnB 1772, 93.8 mm SL). A. Filament on the non-spinous portion of dorsal-fin second (unbranched) ray, indicated by a white arrow; and B. Enlarged urogenital papilla, indicated by a white arrow. Scale bars = 1 cm.

TABLE 1 | Morphometric data for the holotype and 42 paratypes of Pimelodella guato. N = number of specimens; SD = Standard deviation.

Total length (mm)	97.1	47.5–161.2	42	99.9
Standard length (mm)	78.5	37.1–127.9	43	82.5
Percents of standard length
Body depth (dorsal)	17.6	15.0–20.8	43	17.9	1.3
Body width (dorsal)	12.0	11.1–14.1	43	12.9	0.8
Cleithral width	16.0	15.2–18.2	43	16.7	0.6
Head length	29.2	27.2–31.3	43	29.0	1.0
Maxillary-barbel length (left side)	87.1	81.0–113.6	42	94.6	7.4
Outer mental-barbel length (left side)	36.7	28.7–49.7	43	37.3	3.9
Inner mental-barbel length (left side)	21.2	16.8–32.3	43	22.0	3.0
Predorsal length	32.3	28.5–34.1	43	32.3	1.2
Distance between snout tip and terminus of dorsal-fin base	45.4	42.3–48.9	43	46.2	1.2
Distance between snout tip and dorsal-fin distal end	62.1	54.4–75.2	38	58.3	3.4
Dorsal fin to adipose fin	5.0	3.8–22.2	43	7.3	2.9
Dorsal-fin base	15.2	12.7–18.3	43	14.9	1.0
Length of first dorsal-fin ray (unbranched)	30.5	20.1–42.5	29	24.8	4.3
Length of rigid part of first dorsal-fin ray	20.4	14.3–20.7	38	18.5	1.4
Length of second dorsal-fin ray (first branched)	24.0	18.6–24.0	42	21.3	1.2
Length of third dorsal-fin ray (second branched)	19.3	16.4–23.3	42	19.4	1.6
Prepectoral length	23.2	20.0–27.5	43	24.0	2.0
Distance between snout tip and terminus of pectoral-fin base	24.7	22.5–29.0	43	25.9	1.7
Distance between snout tip and pectoral-fin distal end	43.0	38.8–46.0	42	42.4	1.7
Length of first left pectoral-fin ray (unbranched)	21.2	17.3–21.2	39	19.4	1.1
Length of rigid part of first left pectoral-fin ray	18.7	15.5–18.8	43	17.4	0.9
Length of second left pectoral-fin ray (first branched)	19.2	14.7–19.9	42	17.6	1.2
Length of third left pectoral-fin ray (second branched)	17.9	12.4–17.9	41	15.4	1.2
Prepelvic length	42.1	42.1–49.2	43	45.5	1.5
Distance between snout tip and terminus of pelvic-fin base	43.6	43.6–50.8	43	47.1	1.4
Distance between snout tip and pelvic-fin distal end	61.3	58.6–65.5	43	61.4	1.7
Distance between pelvic fins	3.7	2.7–6.4	43	4.3	0.8
Length of first left pelvic-fin ray (unbranched)	18.1	11.5–18.1	43	14.8	1.4
Length of second left pelvic-fin ray (first branched)	18.2	14.3–18.2	43	16.1	1.0
Length of third left pelvic-fin ray (second branched)	17.4	14.0–17.9	42	15.8	1.0
Anal-fin base	10.3	8.6–12.9	43	10.5	0.9
Preanal length	65.7	65.1–71.4	43	67.8	1.4
Distance between snout tip and terminus of anal-fin base	76.7	74.8–82.5	43	77.4	1.5
Distance between snout tip and anal-fin distal end	84.3	82.0–90.3	42	85.2	1.7
Adipose-fin length	39.1	32.5–39.4	43	36.4	1.5
Preadipose length	51.6	51.1–56.4	43	53.2	1.2
Distance between snout tip and adipose-fin base end	86.9	86.3–91.1	43	88.2	1.0
Adipose-fin depth	4.4	3.6–5.2	42	4.4	0.4
Caudal-peduncle length posterior to adipose-fin	10.9	8.1–12.9	43	10.5	0.9
Caudal-peduncle depth at adipose-fin terminus	8.2	6.5–9.2	43	8.0	0.5
Snout-anus distance	48.6	48.2–54.4	42	51.0	1.3
Snout-urogenital papilla distance	55.4	53.2–60.0	40	56.3	1.5
Anus-urogenital papilla distance	6.8	3.9–9.4	40	5.4	1.3
Dorsal lobe of caudal fin length	23.6	21.2–29.2	39	25.8	2.2
Ventral lobe of caudal fin length	26.7	20.8–29.8	42	25.1	1.9
Percents of head length
Head depth	48.4	42.3–63.5	43	51.4	4.0
Head width	48.9	46.1–57.7	43	51.8	3.1
Eye diameter (left)	19.3	17.6–25.3	43	20.3	1.6
Fleshy interorbital	28.2	22.1–28.4	43	24.9	1.7
Bony interorbital	18.0	12.0–20.5	43	17.2	1.5
Mouth gape	32.0	27.3–37.2	42	32.2	2.4
Snout length (left)	35.8	31.2–38.2	43	35.0	1.5
Distance between snout tip and posterior nare (left side)	18.6	15.6–21.5	43	18.5	1.3
Anterior internarial width	12.1	9.1–15.3	43	12.0	1.1
Posterior internarial width	12.1	11.3–15.5	43	13.7	1.0
Intranarial length (left side)	11.9	10.9–15.4	43	12.8	0.9

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Sociedade Brasileira de Ictiologia Neotropical Ichthyology, Núcleo de Pesquisas em Limnologia, Ictiologia e Aquicultura, Universidade Estadual de Maringá., Av. Colombo, 5790, 87020-900, Phone number: +55 44-3011-4632 - Maringá - PR - Brazil
E-mail: neoichth@nupelia.uem.br

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A new species of <i>Pimelodella</i> (Siluriformes: Heptapteridae) from the Paraguai basin, Brazil, with a discussion regarding its distribution

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[1] Edited-by

Carlos DoNascimiento