Two new species of the ornamental loricariid genus <i>Baryancistrus</i> (Siluriformes: Hypostominae) from rio Trombetas basin, Pará, Brazil

Oliveira, Renildo Ribeiro de; Rapp Py-Daniel, Lúcia H.

doi:10.1590/1982-0224-2025-0066

home Sumário navigate_before Anterior Atual Seguinte navigate_next

home Sumário

Original Article • Neotrop. ichthyol. 23 (03) • 2025 • https://doi.org/10.1590/1982-0224-2025-0066 linkcopy

Two new species of the ornamental loricariid genus Baryancistrus (Siluriformes: Hypostominae) from rio Trombetas basin, Pará, Brazil

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

Two new species of Baryancistrus are described from the rio Trombetas basin. These new species were collected in the late 1980’s and were analyzed morphologically and compared to the eight currently assigned species of Baryancistrus. Both new species are distinguished from their congeners by a set of non-unique characters, such as coloration, extension of dorsal-fin membrane, abdominal covering, number of mandibular teeth and size of fins. These new species are only registered for strong-energy and clear waters, powerful cataracts, with rocky substrates, being sometimes, syntopic. The patterns of distribution and morphological features among all Baryancistrus species are discussed, and an identification key is presented. Despite of occurring in a protected area, previous studies on hydroelectric plants for the rio Trombetas, as the Hydropower Plant of Cachoeira Porteira, are being re-examined by current authorities, raising deep concerns on the future conservation of the unique biodiversity of the rio Trombetas basin.

Keywords:
Amazon; Conservation; Freshwater; Hydroelectric; Identification key

vertical_align_top show_chart

more_horiz close
- image
- translate
- link
- article
- vertical_align_top
- file_download
- show_chart
- image
- translate
- link
- article

location_on

Sociedade Brasileira de Ictiologia Neotropical Ichthyology, Departamento de Biologia Animal e Vegetal, CCB, Universidade Estadual de Londrina, Rodovia Celso Garcia Cid, Km 380, Cidade Universitária, 86055-900, Londrina, Paraná, Brazil, Phone +55(43)3371-5151 - Londrina - PR - Brazil
E-mail: neoichth@nupelia.uem.br

rss_feed Acompanhe os números deste periódico no seu leitor de RSS

	H	Mean	Range	SD
Standard length (mm)	229.2	–	71.0–269.3	–
Percentage of standard length
Predorsal length	41.2	42.0	39.2–43.7	1.2
Head length	34.3	35.4	32.6–37.2	1.1
Cleithrum width	35.1	35.0	34.0–36.5	0.7
Cleithrum process width	32.8	33.1	31.9–34.8	0.7
Distance between pectoral and pelvic fin insertions	22.4	23.2	20.7–25.8	1.3
Pectoral spine length	35.9	35.1	32.1–37.5	1.7
Distance between pelvic and anal fins origins	25.4	23.6	20.3–26.0	1.4
Pelvic simple ray length	25.8	27.3	25.8–29.2	1.0
Post anal length	30.7	29.3	27.8–30.7	0.9
Anal simple ray length	10.8	12.3	10.8–13.7	0.9
Dorsal spine length	23.8	27.3	23.8–29.7	2.2
Dorsal-fin base length	40.3	40.7	37.8–44.0	1.6
Dorsal - adipose fin distance	2.0	1.2	0.0–3.4	1.2
Caudal peduncle depth	10.9	11.1	10.6–11.9	0.4
Adipose spine length	7.8	7.3	5.8–8.1	0.7
Adipose - caudal fin distance	23.0	24.1	22.7–25.3	0.8
Body depth at dorsal fin origin	21.1	22.3	20.8–24.2	1.1
Body width at dorsal fin origin	29.0	30.3	29.0–33.2	1.3
Body width at anal fin origin	16.0	17.3	16.0–18.8	0.9
Post-dorsal length	24.5	25.1	23.2–26.9	1.0
Anus - adipose fin distance	4.9	4.1	3.1–4.9	0.6
Percentages on head length
Orbit diameter	19.9	22.1	18.5–26.0	2.5
Snout length	64.9	63.6	59.6–65.7	2.0
Internare distance	13.3	12.9	11.5–13.8	0.8
Interorbital distance	34.8	33.6	30.0–38.1	2.2
Head depth	60.2	60.0	57.0–63.4	2.3
Dentary length	16.9	18.4	16.9–20.8	1.2
Premaxillary length	17.8	18.1	17.1–19.1	0.7
Head width	92.5	88.6	83.1–95.0	4.1
Nare-orbit distance	15.8	14.0	11.6–15.8	1.4
Interbranchial distance	59.2	58.7	56.2–61.7	1.4
Pectoral spine origin - branchial opening distance	23.6	22.8	18.2–27.1	2.5
Lower lip width	55.9	56.5	49.7–61.1	3.6
Lower lip length	16.2	15.1	11.7–17.5	1.5
Counts
Number of premaxillary teeth	35		13–41
Number of dentary teeth	36		14–48
Lateral median plates	25		24–25
Plates between anal and caudal fins	10		9–10
Plates between dorsal and adipose fins	1		0–2
Predorsal plates	3		3–3
Plates along dorsal-fin base	12		11–12

Measurements	H	Mean	Range	SD	N
Standard length (mm)	188.9	123.7	76.1–223.7	38.7	27
Percentage of standard length
Predorsal length	37.2	40.2	37.2–42.8	1.2	27
Head length	32.3	34.3	32.1–35.7	1.0	27
Cleithrum width	29.9	31.8	29.9–33.3	0.9	27
Cleithrum process width	28.1	30.0	27.3–32.0	1.2	27
Distance between pectoral and pelvic fin insertions	25.0	24.4	20.8–27.1	1.4	27
Pectoral spine length	34.6	34.9	33.0–36.9	1.0	27
Distance between pelvic and anal fins origins	24.6	23.3	22.0–25.2	0.9	27
Pelvic simple ray length	26.4	27.7	25.3–29.3	1.1	27
Post anal length	28.6	29.4	27.7–31.0	0.9	27
Anal simple ray length	11.2	12.6	11.2–14.0	0.8	27
Dorsal spine length	36.2	38.1	34.7–41.8	2.1	24
Dorsal-fin base length	45.5	44.7	42.5–47.1	1.3	27
Dorsal - adipose fin distance	0.0	0.0	0.0–00	0.0	27
Caudal peduncle depth	10.9	11.6	10.6–12.5	0.5	27
Adipose spine length	6.8	7.5	6.6–8.3	0.5	26
Adipose - caudal fin distance	21.2	21.9	20.4–23.5	0.8	27
Body depth at dorsal fin origin	18.2	19.8	18.0–23.2	1.2	27
Body width at dorsal fin origin	28.1	28.1	26.0–29.5	0.9	27
Body width at anal fin origin	17.2	16.7	15.3–18.5	0.8	27
Post-dorsal length	21.3	21.2	19.4–22.7	0.7	27
Anus - adipose fin distance	5.0	4.0	2.9–5.0	0.5	27
Percentages on head length
Orbit diameter	17.9	21.1	17.4–24.3	2.0	27
Snout length	66.8	62.6	58.9–67.3	2.4	27
Internare distance	11.8	11.0	9.7–12.4	0.8	27
Interorbital distance	29.1	28.0	25.9–29.6	1.1	27
Head depth	53.9	55.7	53.0–59.9	1.7	27
Dentary length	18.2	17.9	16.0–20.0	1.0	27
Premaxillary length	19.8	18.8	16.8–21.2	1.0	27
Head width	86.9	85.2	81.7–90.7	2.2	27
Nare-orbit distance	11.8	11.8	10.4–13.8	0.9	27
Interbranchial distance	54.7	54.9	51.7–58.1	1.9	27
Pectoral spine origin - branchial opening distance	23.4	22.3	18.8–26.0	1.5	27
Lower lip width	55.5	54.1	49.8–58.8	2.6	27
Lower lip length	14.9	14.7	12.5–15.6	1.3	27
Counts
Number of premaxillary teeth	75		40–76		27
Number of dentary teeth	74		40–74		27
Lateral median plates	25		24–25		27
Plates between anal and caudal fins	10		9–11		27
Plates between dorsal and adipose fins	0		0–0		27
Predorsal plates	3		3–3		27
Plates along dorsal-fin base	13		13–14		27