Redescription of <i>‘Chasmocranus’ brachynema</i> (Heptapteridae: Heptapterini)

The endangered species ‘Chasmocranus’ brachynema is redescribed and diagnosed among other Heptapterini by having the adipose fin extensively fused with the caudal fin, caudal fin shallowly bifurcate, and anal-fin insertion posterior to a vertical through the adipose-fin insertion, in addition to peculiarities of the head and mouth morphology. The species seems to be very rare, known only from five preserved specimens from the main channels of the Paraná and Mogi-Guaçu rivers, and from a tributary of the rio Ivaí, all in the Upper Paraná ecoregion.

Keywords:
Endangered species; Heptapterus longicauda; Rio Ivaí; Rio Mogi-Guaçu; Taxonomic review

Authorship

Gabriel de Carvalho Deprá

Conceptualization

Data curation

Formal analysis

Investigation

Methodology

Visualization

Writing-original draft

Writing-review and editing

Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais, Universidade Estadual de Maringá, Av. Colombo, 5790, 87020-900 Maringá, PR, Brazil. (GCD) gabrieldepra@gmail.com.Universidade Estadual de MaringáBrazilMaringá, BrazilPrograma de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais, Universidade Estadual de Maringá, Av. Colombo, 5790, 87020-900 Maringá, PR, Brazil. (GCD) gabrieldepra@gmail.com.

https://orcid.org/0000-0002-5520-9763

Veronica Slobodian

Conceptualization

Data curation

Formal analysis

Investigation

Methodology

Writing-original draft

Writing-review and editing

Universidade de Brasília, Instituto de Ciências Biológicas, Departamento de Zoologia, Laboratório de Ictiologia Sistemática, Campus Universitário Darcy Ribeiro, Asa Norte, 70910-900 Brasília, DF, Brazil. (VS) vslobodian@unb.br.Universidade de BrasíliaBrazilBrasília, DF, BrazilUniversidade de Brasília, Instituto de Ciências Biológicas, Departamento de Zoologia, Laboratório de Ictiologia Sistemática, Campus Universitário Darcy Ribeiro, Asa Norte, 70910-900 Brasília, DF, Brazil. (VS) vslobodian@unb.br.

Universidade de Brasília, Programa de Pós-Graduação em Zoologia, Campus Universitário Darcy Ribeiro, Asa Norte, 70910-900 Brasília, DF, Brazil.Universidade de BrasíliaBrazilBrasília, DF, BrazilUniversidade de Brasília, Programa de Pós-Graduação em Zoologia, Campus Universitário Darcy Ribeiro, Asa Norte, 70910-900 Brasília, DF, Brazil.

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

Edited-by

Paulo Lucinda

Correspondence

Gabriel de Carvalho Deprá gabrieldepra@gmail.com

Competing Interests

The author declares no competing interests.

Ethical Statement

Not applicable.

SCIMAGO INSTITUTIONS RANKINGS

Figures | Tables

Figures (10)
Tables (1)

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FIGURE 1 |
‘Chasmocranus’ brachynema, EEBP 617, holotype, 128.3 mm SL, rio Mogi-Guaçu at Cachoeira de Emas, upper rio Paraná basin at Pirassununga, State of São Paulo. A. Recent photograph showing the current state of preservation of the specimen. B. Drawings from the original description, evidencing the original coloration of the specimen and the shape of the premaxillary (top) and dentary tooth plates.

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FIGURE 2 |
‘Chasmocranus’ brachynema, NUP 22699, 93.0 mm SL, 23°40’42”S 53°15’47”W, córrego Piava, tributary to the rio das Antas, tributary to the rio Ivaí, upper rio Paraná basin at the municipality of Umuarama, State of Paraná, Brazil.

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FIGURE 3 |
‘Chasmocranus’ brachynema, EEBP 629, 74.9 mm SL, rio Mogi-Guaçu about 1 km downstream from Cachoeira de Emas. Schubart (1964) reported this specimen after the original description.

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FIGURE 4 |
Shape of the premaxillary tooth plates. A. ‘Chasmocranus’ brachynema, NUP 22699, 93.0 mm SL. B.Heptapteruslongicauda, NUP 18882, 85.9 mm SL.

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FIGURE 5 |
Cephalic laterosensory pores in ‘Chasmocranus’ brachynema, NUP 22699, 93.0 mm SL. Well-developed pores are outlined in black, except when hidden by other structures (in which case they are outlined in red). Poorly developed pores are outlined in grey. Abbreviations: i1–6, infraorbital sensory pores 1 to 6; ll1–2, lateral-line sensory pores 1 and 2; pm1–11, preoperculomandibular sensory pores 1 to 11; po1–3, postotic sensory pores 1–3; s1–8, supra-orbital sensory pores 1–8.

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FIGURE 6 |
Partial map of South America, showing the distribution of ‘Chasmocranus’ brachynema in the upper rio Paraná basin. Star, type-locality; losangle, NUP 22699; circle, MZUSP 22511 (rocky river channel submerged in 1974).

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FIGURE 7 |
Localities where ‘Chasmocranus’ brachynema has been collected. A. Type-locality in the rio Mogi-Guaçu at Cachoeira de Emas. In the dry season, the water level lowers considerably, exposing the rocky bottoms. B. In the puddles thus formed, occasional fish specimens get trapped, such as this putative ‘C.’ brachynema (the identification is tentative since the specimen was not preserved). Photographs by Wellington A. M. Peres. C. Córrego Piava. Photograph by Weferson J. Graça.

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FIGURE 8 |
Scatter plot charts of several morphometric characters as percentages of the standard length in ‘Chasmocranus’ brachynema (pink), Heptapterus longicauda (yellow), and Heptapterus sp. 1 (green). Depth at adipose-fin origin, cleithral width, lateral head length to opercle, adipose-fin base length, and pre-adipose length proportions are useful to distinguish between the three species, and dorsal caudal-fin lobe length to distinguish ‘C.’ brachynema and Heptapterus sp. 1 from H. longicauda. Data from the holotype of H. longicauda taken from Borodin (1927Borodin NA. Some new catfishes from Brazil. Am Mus Novit. 1927; (266):1–07.).

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FIGURE 9 |
Heptapterus sp. 1. A. DZSJRP 7973, 45.4 mm SL. B. DZSJRP 7973, 108.4 mm SL. C. DZSJRP 20527, 109.2 mm SL. D. LBP 6414, 133.1 mm SL (photograph by Gabriel Silva). E. DZSJRP 20532, 152.6 mm SL. Notice the allometry in body depth, adipose-fin length, and caudal-fin length – smaller specimens present higher body depth and shorter adipose- and caudal-fin length. A and B were identified as ‘Chasmocranus’ brachynema by Thereza, Langeani (2019Thereza MR, Langeani F. Bagres e cascudos do rio Grande, alto rio Paraná. Curitiba: Editora CRV; 2019.); C and E were identified as ‘I.’ borodini by Thereza, Langeani (2019Thereza MR, Langeani F. Bagres e cascudos do rio Grande, alto rio Paraná. Curitiba: Editora CRV; 2019.); and D was identified as ‘C.’ brachynema by Pereira et al. (2013Pereira LHG, Hanner R, Foresti F, Oliveira C. Can DNA barcoding accurately discriminate megadiverse Neotropical freshwater fish fauna? BMC Genet. 2013; (14):20. https://doi.org/10.1186/1471-2156-14-20.
https://doi.org/10.1186/1471-2156-14-20... ).

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FIGURE 10 |
Heptapterus longicauda, NUP 18882, 74.3 mm SL, 23°40’42”S 53°15’47”W, córrego Piava, tributary to the rio das Antas, tributary to the rio Ivaí, upper rio Paraná basin, municipality of Umuarama, State of Paraná, Brazil.

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TABLE 1 |
Morfometric data of ‘Chasmocranus’ brachynema. *Approximate value. SD = Standard deviation.

FIGURE 1 | ‘Chasmocranus’ brachynema, EEBP 617, holotype, 128.3 mm SL, rio Mogi-Guaçu at Cachoeira de Emas, upper rio Paraná basin at Pirassununga, State of São Paulo. A. Recent photograph showing the current state of preservation of the specimen. B. Drawings from the original description, evidencing the original coloration of the specimen and the shape of the premaxillary (top) and dentary tooth plates.

FIGURE 2 | ‘Chasmocranus’ brachynema, NUP 22699, 93.0 mm SL, 23°40’42”S 53°15’47”W, córrego Piava, tributary to the rio das Antas, tributary to the rio Ivaí, upper rio Paraná basin at the municipality of Umuarama, State of Paraná, Brazil.

FIGURE 3 | ‘Chasmocranus’ brachynema, EEBP 629, 74.9 mm SL, rio Mogi-Guaçu about 1 km downstream from Cachoeira de Emas. Schubart (1964) reported this specimen after the original description.

FIGURE 4 | Shape of the premaxillary tooth plates. A. ‘Chasmocranus’ brachynema, NUP 22699, 93.0 mm SL. B.Heptapteruslongicauda, NUP 18882, 85.9 mm SL.

FIGURE 5 | Cephalic laterosensory pores in ‘Chasmocranus’ brachynema, NUP 22699, 93.0 mm SL. Well-developed pores are outlined in black, except when hidden by other structures (in which case they are outlined in red). Poorly developed pores are outlined in grey. Abbreviations: i1–6, infraorbital sensory pores 1 to 6; ll1–2, lateral-line sensory pores 1 and 2; pm1–11, preoperculomandibular sensory pores 1 to 11; po1–3, postotic sensory pores 1–3; s1–8, supra-orbital sensory pores 1–8.

FIGURE 6 | Partial map of South America, showing the distribution of ‘Chasmocranus’ brachynema in the upper rio Paraná basin. Star, type-locality; losangle, NUP 22699; circle, MZUSP 22511 (rocky river channel submerged in 1974).

FIGURE 7 | Localities where ‘Chasmocranus’ brachynema has been collected. A. Type-locality in the rio Mogi-Guaçu at Cachoeira de Emas. In the dry season, the water level lowers considerably, exposing the rocky bottoms. B. In the puddles thus formed, occasional fish specimens get trapped, such as this putative ‘C.’ brachynema (the identification is tentative since the specimen was not preserved). Photographs by Wellington A. M. Peres. C. Córrego Piava. Photograph by Weferson J. Graça.

FIGURE 8 | Scatter plot charts of several morphometric characters as percentages of the standard length in ‘Chasmocranus’ brachynema (pink), Heptapterus longicauda (yellow), and Heptapterus sp. 1 (green). Depth at adipose-fin origin, cleithral width, lateral head length to opercle, adipose-fin base length, and pre-adipose length proportions are useful to distinguish between the three species, and dorsal caudal-fin lobe length to distinguish ‘C.’ brachynema and Heptapterus sp. 1 from H. longicauda. Data from the holotype of H. longicauda taken from Borodin (1927Borodin NA. Some new catfishes from Brazil. Am Mus Novit. 1927; (266):1–07.).

FIGURE 9 | Heptapterus sp. 1. A. DZSJRP 7973, 45.4 mm SL. B. DZSJRP 7973, 108.4 mm SL. C. DZSJRP 20527, 109.2 mm SL. D. LBP 6414, 133.1 mm SL (photograph by Gabriel Silva). E. DZSJRP 20532, 152.6 mm SL. Notice the allometry in body depth, adipose-fin length, and caudal-fin length – smaller specimens present higher body depth and shorter adipose- and caudal-fin length. A and B were identified as ‘Chasmocranus’ brachynema by Thereza, Langeani (2019Thereza MR, Langeani F. Bagres e cascudos do rio Grande, alto rio Paraná. Curitiba: Editora CRV; 2019.); C and E were identified as ‘I.’ borodini by Thereza, Langeani (2019Thereza MR, Langeani F. Bagres e cascudos do rio Grande, alto rio Paraná. Curitiba: Editora CRV; 2019.); and D was identified as ‘C.’ brachynema by **Pereira et al. (2013**Pereira LHG, Hanner R, Foresti F, Oliveira C. Can DNA barcoding accurately discriminate megadiverse Neotropical freshwater fish fauna? BMC Genet. 2013; (14):20. https://doi.org/10.1186/1471-2156-14-20.
https://doi.org/10.1186/1471-2156-14-20... ).

FIGURE 10 | Heptapterus longicauda, NUP 18882, 74.3 mm SL, 23°40’42”S 53°15’47”W, córrego Piava, tributary to the rio das Antas, tributary to the rio Ivaí, upper rio Paraná basin, municipality of Umuarama, State of Paraná, Brazil.

TABLE 1 | Morfometric data of ‘Chasmocranus’ brachynema. *Approximate value. SD = Standard deviation.

Total length	152*	90*	115.3	–	–	–
Standard length	128.3	74.9	93.0	42.2–50.1
Percentages of standard length
Body depth at dorsal-fin origin	12.2	14.0	11.3	9.4–10.9	11.6	1.7
Body depth at adipose-fin origin	12.5	12.4	13.0	11.4–11.4	12.1	0.7
Caudal-fin depth	–	11.2	16.2	–	13.7	3.6
Body width at dorsal-fin origin	14.0	12.7	13.9	11.8–12.6	13.0	0.9
Cleithral width	18.1	17.8	17.1	17.0–18.0	17.6	0.5
Head length to base of supra-occipital process	22.0	22.4	23.1	22.2–24.4	22.8	1.0
Lateral head length (to posteriormost point of opercle)	25.1	25.2	25.5	25.3–27.0	25.6	0.8
Maxillary-barbel length	23.7	23.2	23.5	22.0–26.3	23.7	1.6
Outer mental-barbel length	10.0	12.0	13.0	10.6–12.3	11.6	1.3
Inner mental-barbel length	7.0	7.9	9.0	8.6–9.5	8.4	1.0
Predorsal length	42.5	43.4	41.3	42.5	42.4	0.9
Distance between snout tip and terminus of dorsal-fin base	54.2	55.9	53.1	54.5–56.4	54.8	1.3
Distance between snout tip and dorsal-fin distal end, adpressed	63.0	65.3	64.5	64.7–65.3	64.5	0.9
Dorsal fin to adipose fin	14.3	13.5	14.4	14.7–15.4	14.5	0.7
Dorsal-fin base	12.5	13.0	12.0	11.8–12.6	12.4	0.4
Length of first dorsal-fin ray (unbranched)	12.9	15.0	14.7	11.6–15.8	14.0	1.7
Length of stiffened part of first dorsal-fin ray	7.3	6.8	7.4	8.1–9.0	7.7	0.8
Length of second dorsal-fin ray (first branched)	14.1	16.3	16.8	15.6	15.7	1.2
Length of third dorsal-fin ray (second branched)	13.3	17.4	16.6	15.8	15.8	1.7
Length of last dorsal-fin ray	9.0	9.7	10.8	10.6	10.0	0.8
Prepectoral length	26.6	24.6	23.9	25.3–28.0	25.7	1.6
Distance between snout tip and terminus of pectoral-fin base	30.2	28.0	28.0	28.9–31.3	29.3	1.4
Distance between snout tip and pectoral-fin distal end, adpressed	40.2	–	–	–	–	–
Length of first pectoral-fin ray (unbranched)	10.2	13.4	12.7	13.4–15.6	13.1	1.9
Length of stiffened part of first pectoral-fin ray	5.0	7.1	6.7	6.6–7.3	6.5	0.9
Length of second pectoral-fin ray (first branched)	12.1	13.6	13.5	14.2–15.4	13.8	1.2
Length of third pectoral-fin ray (second branched)	11.7	13.8	14.9	14.8	13.8	1.5
Pectoral to pelvic-fin distance	18.1	21.8	22.8	17.5–21.0	20.2	2.3
Prepelvic length	47.8	45.4	44.7	45.3–47.2	46.1	1.3
Distance between snout tip and terminus of pelvic-fin base	51.0	48.6	–	48.1–52.1	50.0	1.9
Distance between snout tip and pelvic-fin distal end, adpressed	63.1	60.7	62.2	62.3–65.9	62.8	1.9
Distance between pelvic fins	7.8	7.7	7.3	6.2–6.2	7.0	0.8
Length of first pelvic-fin ray (unbranched)	9.8	10.1	12.3	12.6–13.3	11.6	1.5
Length of second pelvic-fin ray (first branched)	11.7	13.4	14.9	14.5–15.0	13.9	1.4
Length of third pelvic-fin ray (second branched)	12.2	14.6	14.8	15.8–15.9	14.6	1.5
Pelvic to anal-fin distance	27.8	26.7	28.0	24.9–28.9	27.3	1.5
Anal-fin base	9.7	10.8	12.6	9.8–10.9	10.7	1.2
Preanal length	74.5	71.4	70.3	72.5–75.4	72.8	2.1
Distance between snout tip and terminus of anal-fin base	84.6	82.5	83.1	83.4–86.0	83.9	1.4
First branched anal-fin ray length	9.2	11.3	11.8	12.4	11.2	1.4
Distance between snout tip and anal-fin distal end, adpressed	91.3	88.8	92.2	91.0–93.8	91.4	1.8
Adipose-fin length	28.2	29.1	27.5	26.7–28.4	28.0	0.9
Preadipose length	68.3	69.7	67.5	69.7–70.3	69.1	1.1
Distance between snout tip and adipose-fin base end	97.0	97.5	96.7	97.2–97.6	97.2	0.4
Adipose-fin depth	4.6	3.7	3.1	4.2–5.0	4.1	0.7
Caudal-peduncle length	16.3	16.8	18.7	17.2–18.2	17.4	1.0
Caudal-peduncle depth at adipose-fin terminus	8.8	9.2	9.4	8.6–9.2	9.0	0.3
Snout-anus distance	–	51.9	52.7	53.5–54.5	53.2	1.1
Snout-urogenital papilla distance	–	56.2	55.6	56.5–59.7	57.0	1.8
Anus-urogenital papilla distance	–	3.2	3.5	3.1–3.2	3.3	0.2
Dorsal lobe of caudal fin length	–	20.6	24.2	–	22.4	2.6
Ventral lobe of caudal fin length	15.1	18.0	–	–	16.6	2.1
Percentages of head length
Head depth	49.1	42.3	42.2	39.4–40.4	42.7	3.8
Head width	76.1	69.3	70.5	65.8–69.3	70.2	3.7
Eye diameter	15.2	18.0	14.3	18.1–18.4	16.8	1.9
Fleshy interorbital	12.7	10.6	9.3	10.5–11.8	11.0	1.3
Bony interorbital	9.9	7.9	8.0	9.6–11.0	9.3	1.3
Mouth gape	50.9	37.0	38.8	40.9–43.9	42.3	5.4
Snout length	33.9	31.7	33.8	30.7–33.1	32.6	1.4
Distance between snout tip and posterior nare	23.0	23.8	23.6	21.9–24.4	23.4	0.9
Distance between posterior nostril and eye	11.5	10.1	11.4	7.9–7.9	9.7	1.8
Anterior internarial width	21.4	19.6	20.3	16.5–16.7	18.9	2.2
Posterior internarial width	17.7	18.5	17.7	17.3–17.5	17.8	0.5
Intranarial length	14.6	16.9	17.3	15.8–16.5	16.2	1.1

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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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Redescription of <i>‘Chasmocranus’ brachynema</i> (Heptapteridae: Heptapterini)

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[1] Edited-by

Paulo Lucinda