New records and data of Tereancistrum spp. (Monogenoidea: Dactylogyridae) parasites of Characiformes from different localities in Brazil

ABSTRACT

During a parasitological survey of Dactylogyridae infecting the gills of the freshwater fishes Prochilodus lineatus (Valenciennes, 1837), P. brevis Steindachner, 1875, P. nigricans Spix & Agassiz, 1829, and Brycon pesu Müller & Troschel, 1845, several representatives of Tereancistrum Kritsky, Thatcher & Kayton, 1980 were identified. Members of this genus are distinguished by an accessory sclerite associated with the ventral anchor. This study documents new host records and geographic localities for the following species: Tereancistrum kerri Kritsky, Thatcher & Kayton, 1980; T. curimba Lizama, Takemoto & Pavanelli, 2004; T. pirassununguensis Cepeda, Cecarelli & Luque, 2012; T. toksonum Lizama, Takemoto & Pavanelli, 2004; T. spiralocirrum Yamada, Sousa, Diniz & Yamada, 2025; T. ancistrum Yamada, Sousa, Diniz & Yamada, 2025; and T. kritskyi Yamada, Sousa, Diniz & Yamada, 2025. These findings broaden the known host range and biogeographical distribution of Tereancistrum, contributing to the knowledge of monogenoidean diversity in Neotropical freshwater systems.

KEYWORDS:
Freshwater fish; Neotropical Region; taxonomy

INTRODUCTION

Species of Tereancistrum Kritsky, Thatcher & Kayton, 1980 are dactylogyrids of freshwater fishes belonging to Prochilodontidae, Anostomidae, and Bryconidae (Cohen et al. 2013, Karling et al. 2014, Zago et al. 2017, Leite et al. 2020, Hasuike et al. 2025). The main diagnostic characteristic of this genus is a spatulated accessory sclerite associated with the ventral anchor. To date, 15 species of Tereancistrum have been described or reported parasitizing Neotropical characiforms: Tereancistrum kerri Kritsky, Thatcher & Kayton, 1980 (type species); T. parvus Kritsky, Thatcher & Kayton, 1980; T. ornatus Kritsky, Thatcher & Kayton, 1980; T. curimba Lizama, Takemoto & Pavanelli, 2004; T. arcuatus Cohen, Kohn & Boeger, 2012; T. pirassununguensis Cepeda, Cecarelli & Luque, 2012; T. paranaensis Karling, Lopes, Takemoto & Pavanelli, 2014; T. flabellum Zago, Yamada, Franceschini, Bongiovani, Yamada & Silva, 2017; T. takemotoi Leite, Pelegrini, Azevedo & Abdallah, 2020; T. toksonum Lizama, Takemoto & Pavanelli, 2004; T. campanum Hasuike, Scorsim, Arjona, Amaral, Damacena-Silva, Araújo, Bellay, de Oliveira & Takemoto, 2025; T. spiralocirrum Yamada, Sousa, Diniz & Yamada, 2025; T. ancistrum Yamada, Sousa, Diniz & Yamada, 2025; T. kritskyi Yamada, Sousa, Diniz & Yamada, 2025; and T. scleritelongatum Yamada, Sousa, Diniz & Yamada, 2025 (Kritsky et al. 1980, Cohen et al. 2013, Karling et al. 2014, Zago et al. 2017, Leite et al. 2020, Hasuike et al. 2025, Yamada et al. 2025).

The hosts studied herein include three species of Prochilodus Spix & Agassiz, 1829, Prochilodus lineatus (Valenciennes, 1837), P. brevis Steindachner, 1875, and P. nigricans Spix & Agassiz, 1829, and Brycon pesu Müller & Troschel, 1845. Prochilodus comprises 13 species widely distributed in Brazilian watersheds (Toledo-Piza et al. 2024). Due to their abundance, these species represent economically important fishing resources (Barroca et al. 2012), particularly in the Southeast, Northeast, and Amazon regions (Ninhaus-Silveira et al. 2006, Lopes et al. 2014, Bonilla-Castillo et al. 2018). Brycon Müller & Troschel, 1844 is one of the most diverse Neotropical taxa of freshwater neotropical fish, with over 40 described species primarily found in South America (Arruda et al. 2019). Brycon pesu, known as “beiradeira,” inhabits flowing waters over sand and rocks and is common in the Amazon basin (Panarari-Antunes et al. 2008).

Examination of material collected from these hosts across different localities revealed several species of Tereancistrum. This paper provides new host and biogeographical data for T. ancistrum, T. curimba, T. kerri, T. kritskyi, T. pirassununguensis, T. spiralocirrum, T. takemotoi, and T. toksonum.

MATERIAL AND METHODS

Samples of P. lineatus and P. nigricans were collected from the Tocantins River, near the urban perimeter of Imperatriz (village of Embiral), Maranhão, Brazil, 5°27’50”S; 47°33’48”W), and the Juruá River (Acre, Brazil, 7°40’34.1”S; 72°39’39.5”W). Prochilodus brevis and P. nigricans were obtained from the Rodolfo von Ihering aquaculture research center at the “Departamento de Obras Contra as Secas” (DNOCS) (Pentecoste, Ceará, Brazil, 3°49’08.8”S; 39°06’38.0”W). Samples of B. pesu were collected from the Tocantins River near the “Universidade Estadual Tocantina do Maranhão (UEMASUL)”, in the village of Embiral. Fishes were caught by local fishermen using gill nets, hooks, and lines.

Gills were removed and placed in hot water (~65 °C) to relax parasites, then shaken to detach dactylogyrids from the gill filaments. Specimens were fixed in either 70% ethanol or 5% formalin. Gill arches and sediments were examined under a stereomicroscope for parasite collection. Specimens were mounted in Hoyer’s medium to study sclerotized structures, including the copulatory complex and haptoral sclerites.

Measurements are provided in micrometers (µm) as range values followed by the mean and number of measured structures in parentheses. Specimens were analyzed using an Olympus BX 41 microscope with phase contrast and a Zeiss Axioskop 2 Plus microscope with differential interference contrast, both equipped with camera lucida for drawings. Images were captured with a SONY MPEG Movie EX DSC-S75 digital camera. Vouchers were deposited in the “Coleção Helmintológica do Instituto Oswaldo Cruz” (CHIOC), Brazil.

RESULTS

Class Monogenoidea Bychowsky, 1937

Subclass Polyonchoinea Bychowsky, 1937

Order Dactylogyridea Bychowsky, 1937

Dactylogyridae Bychowsky, 1933

Tereancistrum Kritsky, Thatcher & Kayton, 1980

Tereancistrum ancistrum Yamada, Sousa, Diniz & Yamada, 2025

Figs 1A-G, 2A-C

Hosts and localities. Prochilodus lineatus and P. nigri cans: Tocantins River, close to the urban perimeter of Imperatriz, in the village of Embiral, state of Maranhão, Brazil; P. nigricans: Juruá River, state of Acre, Brazil; P. brevis: aquaria of the research center in aquaculture Rodolfo von Ihering from the “Departamento de Obras Contra as Secas (DNOCS)”. CHIOC numbers 40851, 40852, 40853.

Previous records. Prochilodus brevis (type-host): Lima Campos reservoir dam, Salgado River basin, municipality of Icó, state of Ceará, Brazil (type-locality); Ubaldinho reservoir, Salgado River basin, municipality of Cedro, Ceará state, Brazil; Rosário reservoir, Salgado River basin, municipality of Lavras da Mangabeira, state of Ceará, Brazil

Figure 1
Tereancistrum ancistrum: (A) total, ventral view; (B) male copulatory complex; (C, D) hooks; (E) ventral anchor with accessory sclerite; (F) dorsal anchor; (G) ventral bar. Scale bars: A = 100 µm, B-D = 10 µm, E-G = 20 µm.

Figure 2
Tereancistrum ancistrum: (A) total, ventral view; (B) haptor; (C) male copulatory complex. Scale bars: A = 100 µm, B = 50 µm, C = 5 µm.

Main measures. (Based on 23 specimens “in toto” mounted in Hoyer’s medium; original measurements in brackets): Body 271 (208-380; n = 19) [272 (230-355; n = 11)] long by 84 (50-130; n = 23) [52 (36-64; n = 13)] wide. Pharynx 21 (20-22; n = 3) long, 26 (22-30; n = 3) [15 (11-18; n = 10)] wide. Male copulatory complex (MCO) 9 (7-12; n = 21) [9 (8-12; n = 13)] long; accessory piece 12 (11-14; n = 19) [12 (10-16; n = 13)] long. Haptor 68 (50-85; n = 22) [49 (33-77; n = 8)] long. Hooks 17 (13-23; n = 20) [18 (16-20; n = 28)]. Ventral anchor 33 (18-42; n = 21) [38 (35-39; n = 15)] long, 14 (10-17; n = 22) [12 (10-14; n = 15)] base. Accessory sclerite of the ventral anchor 18 (11-23; n = 23) [14 (12-18; n = 15)]. Dorsal anchor 18 (10-20; n = 21) [18 (16-22; n = 15)] long, 3 (2-5; n = 21) [2 (1-3; n = 15)] base. Ventral bar 51 (35-61; n = 22) [42 (38-47; n = 15)]. Germarium 49 (n = 1) [52 (35-68; n = 5)] long, 23 (n = 1) [31 (22-40; n = 3)] wide.

Remarks: Tereancistrum ancistrum, recently described parasitizing P. brevis from a reservoir in Ceará, Brazil, was recorded here infecting P. lineatus, P. brevis, and P. nigricans in new localities. These findings expand its distribution to the Tocantins River (Maranhão), Juruá River (Acre), and DNOCS aquaria (Ceará), representing new host and geographical records for T. ancistrum.

Tereancistrum spiralocirrum Yamada, Sousa, Diniz & Yamada, 2025

Figs 3A-H, 4A-C

Host and locality. Prochilodus nigricans: Juruá River, state of Acre, Brazil. CHIOC numbers 40861, 40862 a,b

Previous records. Prochilodus brevis (type-host): Rosário reservoir, Salgado River basin, municipality of Lavras da Mangabeira, state of Ceará, Brazil (type-locality); Ubaldinho reservoir, Salgado River basin, municipality of Cedro, Ceará, Brazil.

Figure 3
Tereancistrum spiralocirrum (A) total, ventral view; (B) male copulatory complex; (C) vagina; (D) ventral anchor with accessory sclerite; (E) hook; (F); dorsal anchor; (G) ventral bar; (H) dorsal bar. Scale bars: A = 100 µm, B = 20 µm, C= 40 µm, D, F, G, H = 20 µm, E = 10 µm.

Figure 4
Tereancistrum spiralocirrum: (A) total, ventral view; (B) haptor; (C) male copulatory complex. Scale bars: A = 100 µm, B = 50 µm, C = 10 µm.

Main measures. (Based on three specimens “in toto”, mounted in Hoyer’s medium; original measurements in brackets): Body 410 and 500 (n = 2) [486 (405-624; n = 5)] long by 120 and 150 (n = 2) [84 (70-90; n = 5) wide. Pharynx 32 (n = 1) [24 (20-30; n = 8)] long, 28 (n = 1) wide. Male copulatory organ (MCO) 22 (n = 2) [20 (13-23; n = 10)] long; accessory piece 16 (n = 1) [13 (12-16; n = 10)] long. Ventral anchor 30 (28-35; n = 3) [34 (31-37; n = 10)] long, 9 (6-12; n = 3) [11 (8-14; n = 10)]. Hooks 17 (14-20; n = 3) [18 (15-20; n = 56)]. Dorsal anchor 12 (10-13; n = 3) [15 (14-17; n = 10)] long, 10 (8-12; n = 3) [5 (4-6; n = 10) base. Accessory sclerite of ventral anchor 7 (5-12; n = 3) [8 (5-10; n = 8)]. Haptor 82 (65-100; n = 3) [73 (61-80; n = 8)] wide. Ventral bar 55 (45-60; n = 3) [54 (50-57; n = 10)]. Dorsal bar 15 and 22 (n = 2) [17 (13-20; n = 9)]. Germarium 70 and 100 (n = 2) [58 (48-64; n = 6)] long, 33 and 50 (n = 2) [24 (16-33; n = 6)] wide.

Remarks: Tereancistrum spiralocirrum was originally described parasitizing the gills of P. brevis collected from a reservoir in Ceará, northeastern Brazil. In the present study, specimens of T. spiralocirrum were identified infecting P. nigricans in the Juruá River, located in Acre, western Amazon region. This finding expands the known host range of T. spiralocirrum to include P. nigricans and represents the first record of this monogenean species in the hydrographic basin of the Juruá River, thereby broadening its geographical distribution within Brazil.

Tereancistrum kritskyi Yamada, Sousa, Diniz & Yamada, 2025

Figs 5A-G; 6A-C

Host and localities. Prochilodus nigricans. Juruá River, state of Acre, Brazil; Tocantins River, close to the urban perimeter of Imperatriz, in the village of Embiral, state of Maranhão, Brazil. CHIOC number 40859 a-b.

Previous records. Prochilodus brevis (type-host): Lima Campos reservoir, Salgado River basin, municipality of Icó, state of Ceará, Brazil (type-locality); Ubaldinho reservoir, Salgado River basin, municipality of Cedro, Ceará state, Brazil; Rosário reservoir, Salgado River basin, municipality of Lavras da Mangabeira, state of Ceará, Brazil.

Figure 5
Tereancistrum kritskyi: (A) total, ventral view; (B) male copulatory complex; (C) ventral anchor with accessory sclerite; (D) dorsal anchor; (E) dorsal bar; (F) hook; (G) ventral bar. Scale bars: A = 100 µm, B = 5 µm, C = 20 µm, D, G = 10 µm, E, F = 20 µm.

Figure 6
Tereancistrum kritskyi: (A) total, ventral view; (B) haptor; (C) male copulatory complex. Scale bars: A = 100 µm, B = 50 µm, C = 5 µm.

Main measures. (Based on nine specimens “in toto”, mounted in Hoyer’s medium; original measurements in brackets): Body 280 (215-325; n = 7) [297 (252-350; n = 10)] long by 84 (45-105; n = 9) [54 (32-76; n = 9)] wide. Male copulatory organ 10 (7-14; n = 6) [10 (8-14; n = 12)] long; accessory piece 12 (10-15; n = 6) [8 (5-13; n = 11)] long. Haptor 69 (55-90; n = 7) [68 (56-82; n = 10)] wide. Ventral anchor 28 (23-30; n = 7) [38 (35-39; n = 12)] long, 13 (10-17; n = 8) [12 (9- 14; n = 12) base. Dorsal anchor 13 (10-16; n = 9) [14 (13-15; n = 12)] long, 5 (3-8; n = 7) [3 (2-4; n = 12)] at base. Ventral bar 62 (47-73; n = 7) [55 (49-60; n = 11)]. Dorsal bar 13 (11-18, n = 7) [13 (10-16; n = 8)]. Hooks 16 (12-23; n = 7) [17 (15-20; n = 29)]. Accessory sclerite of ventral anchor 25 (18-30; n = 9) [21 (17-23; n = 12)] long.

Remarks: Tereancistrum kritskyi was described parasitizing P. brevis in a reservoir in Ceará. In the present study, this parasite is reported in P. nigricans in the localities of Juruá River, Acre, and Tocantins River, Maranhão, representing a new host and localities for the species. The accessory piece described by Yamada et al. (2025) appears to be divided into two distinct portions, whereas in the present material it is consistently observed as a single structure. Examination of the type series, including the holotype (40.634) and paratypes (40.635-40.639), reveals that the holotype exhibits an accessory piece morphology comparable to that observed in the present study, i.e., a single structure, while the paratypes correspond more closely to the condition depicted in the original illustrations, i.e., divided in two distinct portions. The differences observed in the present study and original specimens are probably due to an instraspecific variation.

Tereancistrum toksonum Lizama, Takemoto & Pavanelli, 2004

Figs 7A-F, 8A-C

Hosts and localities. Prochilodus lineatus (Valenciennes, 1837): Tocantins River, close to the urban perimeter of Imperatriz, in the village of Embiral, state of Maranhão, Brazil (5°27’50”S; 47°33’48”W); Prochilodus nigricans Spix & Agassiz, 1829: Juruá River, state of Acre, Brazil (7°40’34.1”S, 72°39’39.5W) and Tocantins River, close to the urban perimeter of Imperatriz, in the village of Embiral, state of Maranhão, Brazil (5°27’50”S; 47°33’48”W)” and Prochilodus brevis: aquaria of the research center in aquiculture Rodolfo von Ihering from the “Departamento de Obras Contra as Secas (DNOCS)”, state of Ceará. CHIOC numbers 40865, 40866.

Previous records. Prochilodus lineatus (type-host): Upper Paraná River floodplain, Brazil (type-locality) (Lizama et al. 2004, Takemoto et al. 2009); Peixe River, state of São Paulo, Brazil (Dias et al. 2017); The stretch of the Batalha River, in the municipality of Reginópolis, state of São Paulo, Brazil (Leite et al. 2018); Prochilodus nigricans: floodplain lakes of the Solimões River, state of Amazonas, Brazil (Arévalo et al. 2018); Xingu River, Amazon River, around Altamira, state of Pará, Brazil (Moreira et al. 2016); Moa River, Ipixuna River and Croa River, state of Acre, Brazil (Silva et al. 2023).

Figure 7
Tereancistrum toksonum: (A) male copulatory complex; (B) vagina; (C) hooks; (D) Ventral anchor with accessory sclerite, (E) ventral bar; (F) dorsal anchor; (G) dorsal bar. Scale bars: A, D-G = 25 µm, B = 20 µm, C = 10 µm.

Figure 8
Tereancistrum toksonum: (A) total, ventral view; (B) haptor; (C) male copulatory complex. Scale bars: A = 200 µm, B = 25 µm, C = 10 µm.

Main measures. (Based on 10 specimens “in toto” mounted in Hoyer’s medium; original measurements in brackets). Body 488 (340-660; n = 9) [511 (300-664; n = 15)] long, 174 (120-230; n = 10) [116 (79-156; n = 15)] wide. Pharynx 49 (n = 1) long, 35 (n = 1) [41 (27-78; n = 13)] wide. Haptor 124 (90-210; n = 10) [82 (63-103; n = 14)] with 7 pairs of hooks. Ventral bar 48 (34-60; n = 10) [52 (36-99; n = 14)] long. Dorsal bar 48 (45-54; n = 10) [46 (29-69; n = 14)] long. Ventral anchor 26 (15-38; n = 9) [37 (27-48; n = 15)] long, 8 (5-15; n = 10) [22 (20-23; n = 5)] wide. Accessory sclerite of ventral anchor 33 (30-39; n = 10) [32 (20-64; n = 16)]. Dorsal anchor 19 (13-32; n = 10) [34 (21-40; n = 13)] long, 19 (14-26; n = 10) [23 (15-35; n = 6)] wide. Hooks similar in size and shape 12 (8-15; n = 9) [13 (11-17; n = 15)] long. Male copulatory organ 22 (19-25; n = 10) [19 (16-21; n = 8)] long. Accessory piece 23 (15-25; n = 10) [17 (11-25; n = 9)] long.

Remarks: Tereancistrum toksonum was described by Lizama et al. (2004) parasitizing P. lineatus in the locality of Paraná River. After its description, this parasite was reported parasitizing its type-host in the localities of Peixe River and Batalha River, in São Paulo, and was also reported parasitizing P. nigricans in the localities of Solimões River, Amazonas, Xingu River, Pará, Moa River, Ipixuna River, and Croa River, in Acre. In the present study, T. toksonum is reported from P. lineatus in the locality of Middle Tocantins River, Maranhão, and from P. brevis, from the aquaria of the research center in aquiculture Rodolfo von Ihering from the “Departamento de Obras Contra as Secas (DNOCS)”, in Pentecoste City, Ceará, Brazil, constituting new biogeographical data.

Tereancistrum takemotoi Leite, Pelegrini, Azevedo & Abdallah, 2020

Figs 9A-F, 10A-C

Hosts and localities. Prochilodus lineatus (Valenciennes, 1837): Tocantins River, close to the urban perimeter of Imperatriz, in the village of Embiral, State of Maranhão, Brazil (5°27’50”S; 47°33’48”W); Prochilodus nigricans Spix & Agassiz, 1829: Juruá River, State of Acre, Brazil (7°40’34.1”S; 72°39’39.5W) and Tocantins River, close to the urban perimeter of Imperatriz, in the village of Embiral, State of Maranhão, Brazil (5°27’50”S; 47°33’48”W)” and P. brevis: aquaria of the research center in aquiculture Rodolfo von Ihering from the “Departamento de Obras Contra as Secas (DNOCS)”, State of Ceará. CHIOC numbers 40863, 40864.

Previous records. Prochilodus lineatus (type-host): Batalha River, Tietê-Batalha River basin, São Paulo State, Brazil (type-locality).

Figure 9
Tereancistrum takemotoi: (A) male copulatory complex; (B); vagina; (C) hook; (D) ventral anchor with accessory sclerite; (E) ventral bar; (F) dorsal anchor; (G) dorsal bar. Scale bars: A = 30 µm, B = 20 µm, C = 10 µm, D = 20 µm, E-F = 30 µm, G = 20 µm.

Figure 10
Tereancistrum takemotoi: (A) total, ventral view; (B) haptor; (C) male copulatory complex. Scale bars: A = 100 µm, B = 50 µm, C = 5 µm.

Main measures. (Based on 17 specimens “in toto” mounted in Hoyer’s medium; original measurements in brackets). Body 554 (370-750; n = 16) [539.2 ± 69.5 (359.7-684.1)] long, 182 (140-250; n = 16) [130.1 ± 27.6 (95.1-200)] wide. Haptor 129 (90-240; n = 17) [94.5 ± 10.8 (78-109)] with 7 pairs of hooks. Ventral bar 47 (38-56; n = 17) [50.4 ± 5.7 (42.7-58.7)] long. Dorsal bar 50 (38-59; n = 17) [38.9 v± 3.9 (30.8-45.3)] long. Ventral anchor 31, (20-37; n = 17) [32.3 ± 2.1 (27.1-35.1)] long, 9 (5-15; n = 17) [13.7 ± 2.4 (9.5-16.7)] wide. Accessory sclerite of ventral anchor 33 (27-37; n = 17) [ 30.7 ± 2.1 (28.3-34.7)]. Dorsal anchor 25 (13-34; n = 17) [31.7 ± 1.6 (27.9-33.4)] long, 18 (10-28; n = 17) [23.1 ± 2.6 (17.4-26.3)] wide. Hooks similar in size and shape 13 (10-15; n = 16) [12 ± 1.6 (10.2-14.6)] long. Male copulatory organ 21 (18-24; n = 17) [19.4 ± 2.2 (14.8-21.6)] long. Accessory piece 23 (13-30; n = 17) [23.2 ± 2.4 (20-27.1)] long.

Remarks: Tereancistrum takemotoi was described from Tiete-Batalha River Basin, São Paulo, parasitizing P. lineatus (Leite et al. 2020). In the original description, the authors stated that this species is differentiated from T. toksonum by the number of rings of the MCO (1¼ counterclockwise rings in T. toksonum and 2¼ rings in T. takemotoi), by the dorsal bar, that in T. takemotoi has a Y-shaped dorsal bar and undulations in the anterior portion, while absent in T. toksonum and differences in the ventral bar of both species: it is anvil-shaped in T. takemotoi and arched in T. toksonum. Studying the types of T. toksonum from the CHIOC 36.229 (holotype), 36.230 and 36.231 (paratypes) and 38.411 (voucher), it is possible to observe that the number of rings is similar, the dorsal bar of some specimens of T. toksonum shows the undulations similar to those observed in T. takemotoi and both species share the same morphology of the ventral bar.

Tereancistrum pirassununguesis Cepeda, Cecarelli & Luque, 2012

Figs 11A-F, 12A-C

Host and locality. Prochilodus brevis: aquaria of the research center in aquiculture Rodolfo von Ihering from the “Departamento de Obras Contra as Secas” (DNOCS), state of Ceará; P. nigricans: Tocantins River, close to the urban perimeter of Imperatriz, in the village of Embiral, state of Maranhão, Brazil; Juruá River, state of Acre, Brazil. CHIOC numbers 40860 a-c.

Previous records. Prochilodus lineatus (type-host): Mogi Guaçu River, Southeastern State of São Paulo (type-locality) (Cepeda et al. 2012).

Figure 11
Tereancistrum pirassununguensis: (A) male copulatory complex.; (B) hooks; (C) ventral anchor with accessory sclerite; (D) ventral bar; (E) dorsal anchor; (F) dorsal bar. Scale bars: A = 15 µm, B = 10 µm, C-F = 25 µm.

Figure 12
Tereancistrum pirassununguesis: (A) total, ventral view; (B) haptor; (C) male copulatory complex. Scale bars: A = 100 µm, B = 50 µm, C = 5 µm.

Main measures. (Based on 22 specimens “in toto” mounted in Hoyer’s medium; original measurements in brackets). Body 215 (100-340; n = 21) [193 (175-222; n = 9)] long, 97 (50-170; n = 22) [82 (61-112; n = 6)] wide. Pharynx 20 (n = 2) long, 15 and 18 (n = 2) [13 (11-16; n = 4)] wide. Male copulatory organ 11 (7-15; n = 21) [8 (7-9; n = 3)] long; accessory piece 11 (10-16; n = 22) [13 (11-14; n = 3)] long. Haptor 81 (55-118; n = 22) [57-60; n = 2] with 7 pairs of hooks. Hooks similar in size and shape 13 (10-15; n = 21) [13 (13-14; n = 11)] long. Ventral bar 50 (35-70; n = 21) [38 (33-44; n = 9)] long. Ventral anchor 23 (15-30; n = 22) [21 (21-22; n = 3)] long, 14 (7-20; n = 22) [13 (12-13; n = 3)] wide. Accessory sclerite of ventral anchor 8 (4-13; n = 20) [9 (8-11; n = 12)]. Dorsal bar 44 (30-73; n = 22) [27 (22-30; n = 8)] long, wide. Dorsal anchor 22 (13-28; n = 22) [23 (21-24; n = 8)] long, 15 (5-23; n = 22) [18 (15-22; n = 8)] wide.

Remarks: Tereancistrum pirassununguensis was originally described from Schizodon nasutus Kner, 1858, in the locality of Mogi-Guaçu River, Pirassununga, São Paulo (Cepeda et al. 2012). After the description, this species has not been recorded in another locality or host. In the present study, T. pirassununguensis is reported in the Tocantins River, Maranhão, and in the Juruá River, Acre, parasitizing P. nigricans. This species is also reported on fishes collected from the aquaria of DNOCS, Ceará, parasitizing P. brevis, representing a new host record and new localities, increasing its geographical distribution.

Tereancistrum curimba Lizama, Takemoto & Pavanelli, 2004

Figs 13A-F, 14A-C

Hosts and localities. Prochilodus brevis: aquaria of the research center in aquiculture Rodolfo von Ihering from the “Departamento de Obras Contra as Secas (DNOCS)”, state of Ceará, Brazil; P. nigricans: Juruá River, state of Acre, Brazil (7°40’34.1”S; 72°39’39.5”W); P. lineatus: Tocantins River, close to the urban perimeter of Imperatriz, in the village of Embiral, state of Maranhão, Brazil (new locality) (5°27’50”S; 47°33’48”W). CHIOC numbers 40854, 40855, 40856.

Previous records. Prochilodus lineatus (type-host): floodplain of the upper Paraná River, State of Paraná, Brazil (type-locality) (Lizama et al. 2004); P. nigricans: floodplain lakes of the Solimões River, state of Amazonas, Brazil (Arévalo et al. 2018); fish pond from CIFAB-IIAP, Iquitos-Peru (Morey et al. 2023); Juruá River (7°39’06.0”S 72°38’57.0”W), Moa River (7°37’11.4”S 72°48’12.9”W), Ipixuna River (7°17’13.0”S 72°36’49.0” W) and Croa River (7°44’18.6”S 72°33 ‘00.5” W), state of Acre, Brazil (Silva et al. 2023).

Figure 13
Tereancistrum curimba: (A) male copulatory complex; (B) hooks; (C) ventral anchor with accessory sclerite; (D) ventral bar; (E) dorsal anchor; (F) dorsal bar. Scale bars: A, C-F = 25 µm, B = 10 µm.

Figure 14
Tereancistrum curimba: (A) total, ventral view; (B) haptor; (C) male copulatory complex. Scale bars: A = 100 µm; B = 50 µm, C=5 µm.

Main measures (Based on 19 specimens “in toto” mounted in Hoyer’s medium; original measurements in brackets). Body 610 (230-900; n = 12) [825 (560-1,178; n = 20)] long, 190 (120-300; n = 19) [133 (44-199; n = 22)] wide. Pharynx 50 (n = 1) long, 41 (n = 1) [28 (16-39; n = 19)] wide. Male copulatory organ 23 (17-35; n = 19) [22 (14-29; n = 18)] long; accessory piece 20 (13-27; n = 17) [29 (14-37; n = 15)] long. Haptor 113 (80-150; n = 19) [87 (69-122; n = 19)]. Hooks similar in size and shape 13 (10-16; n = 12) [14 (12-19; n = 16)]. Ventral bar 69 (53-90; n = 18) [52 (33-83; n = 19)] long. Ventral anchor 32 (17-43; n = 19) [41 (29-51; n = 20)] long, 19 (8-35; n = 19) [25 (19-35; n = 15)] wide. Accessory sclerite of ventral anchor 37 (30-45; n = 18) [32 (25-48; n = 19)]. Dorsal bar 53 (22-81; n = 19) [45 (36-62; n = 14)] long. Dorsal anchor 28 (23-35; n = 18) [41 (29-55; n = 19)] long, 30 (9-45; n = 17) [35 (15-50; n = 13)] wide.

Remarks: Tereancistrum curimba was originally described from P. lineatus from the upper Paraná River (Lizama et al. 2004). Later, the species was reported from type host and from the congeneric P. nigricans, from different localities (Arévalo et al. 2018, Lehun et al. 2020, Morey et al. 2023, Piña et al. 2017, Takemoto et al. 2009, Zago et al. 2017). The majority of the studies reported on the occurrence of the species but did not present morphometric data. In the present study, this parasite was reported in the Juruá River, Acre, parasitizing P. nigricans, in the Tocantins River, Maranhão, parasitizing P. lineatus and in the aquaria of the research center in aquiculture Rodolfo von Ihering from the “Departamento de Obras Contra as Secas” (DNOCS), Ceará, parasitizing P. brevis. It was the first time that this parasite was registered in these locations, increasing the distributions of this parasite in Brazil. Also in this study, it was the first time that T. curimba was described in host-parasite association with P. brevis, also increasing the range of hosts of this species.

Tereancistrum kerri Kritsky, Thatcher & Kayton, 1980

Figs 15A-F, 16A-C

Host and locality. Brycon pesu: Tocantins River, close to the urban perimeter of Imperatriz, in the village of Embiral, state of Maranhão, Brazil. CHIOC numbers 40857, 40858 a-b.

Previous records. Brycon melanopterus (Cope, 1872) (type-host): Januaca Lake, near Manaus, state of Amazonas, Brazil (type-locality) (Kritsky et al. 1980); Brycon amazonicus (Spix & Agassiz, 1829): Igarapé channel, 17 km from Manaus, Amazonas, Brazil (Andrade & Malta, 2006); Brycon nattereri Günther, 1864: Traíras River, Niquelândia city, state of Goiás (Hasuike et al. 2025).

Figure 15
Tereancistrum kerri: (A) male copulatory complex; (B) hook; (C) ventral anchor with accessory sclerite; (D) ventral bar; (E) dorsal anchor; (F) dorsal bar. Scale bars: A, C-E = 25 µm, B, F = 10 µm.

Figure 16
Tereancistrum kerri: (A) total, ventral view; (B) haptor; (C) male copulatory complex. Scale bars: A = 100 µm, B = 30 µm, C = 10 µm.

Main measures. (Based on 12 specimens “in toto” mounted in Hoyer’s medium; original measurements in brackets). Body 250 (163-315, n = 10) [340 (275-400)] long, 77 (40-115, n = 12) [80 (51-102)] wide. Pharynx 13 (n = 1) long, 13 (n = 1) [21 (20-22)] wide. Male copulatory complex 36 (20-50, n = 10) [61 (55-72)] ring diameter; accessory piece 36 (26-50, n = 9) [63 (46-72)]. Haptor 74 (55-100, n = 12) [93 (51-122)] wide. Hooks similar in size and shape 16 (11-20, n = 11) [1, 5, 16 (15-17). Pairs 2, 3, 4, 6, 7, 22 (21-23)]. Ventral bar 46 (36-57, n = 10) [62 (54-74)]. Ventral anchor 36 (30-43, n = 12) [55 (51-59)] long, 14 (6-20, n = 12) [17 (15-18)] base. Accessory sclerite of ventral anchor 32 (20-40, n = 12) [50 (39-56)]. Dorsal bar 23 (19-30, n = 8) [33 (30-36)]. Dorsal anchor 34 (30-37, n = 11) [46 (43-50)] long, 9 (5-16, n = 11) [13 (12-14)] base.

Remarks: Tereancistrum kerri, type species of the genus, was described by Kritsky et al. (1980) parasitizing B. melanopterus at Janauacá Lake, near Manaus, Amazonas. After being described, it was recorded by Andrade & Malta (2006) in a highland stream channel at a private estate 17 km from Manaus, Amazonas, parasitizing B. amazonicus, and by Hasuike et al. (2025) in Traíras River, Niquelândia city, Goiás, parasitizing B. nattereri, also members of the Bryconidae. In this study, this parasite was found in the gills of B. pesu in Tocantins River, in Maranhão state, reporting a new host and locality for this parasite.

DISCUSSION

This study reports six species of Tereancistrum in different hosts: T. toksonum, T. pirassununguensis, T. curimba, T. ancistrum, T. spiralocirrum, T. kritskyi (from Prochilodus spp.), and T. kerri (from B. pesu). These findings reinforce the hypothesis that Tereancistrum species exhibit a high degree of host specificity, particularly among phylogenetically closely related hosts within the same family.

In addition to the records in the present study, other species of the genus exhibit a diversity of hosts and localities. Tereancistrum flabellum was recorded parasitizing Leporinus friderici (Bloch, 1794), Megaleporinus elongatus (Valenciennes, 1850), and Leporinus amblyrhynchus Garavello & Britski, 1987 in the Sapucaí-Mirim River, Grande River Basin, and Jurumirim Reservoir, São Paulo, Brazil (Zago et al. 2017). Tereancistrum ornatus was described by Kritsky et al. (1980) from the Cauca River, Colombia, parasitizing Prochilodus reticulatus Valenciennes, 1850. Subsequently, this species was reported from Hemibrycon surinamensis Géry, 1962 and P. lineatus in the Matapi River (Amapá) and Peixe/Batalha Rivers (São Paulo) (Dias et al. 2017, Leite et al. 2018, Sousa et al. 2019). Tereancistrum paranaensis was collected from Schizodon borellii (Boulenger, 1900) in the upper Paraná River floodplain (Karling et al. 2014) and later recorded in Megaleporinus obtusidens (Valenciennes, 1837) and Schizodon intermedius Garavello & Britski, 1990 in Lake Guaíba (Rio Grande do Sul) and the Veados River (São Paulo) (Abdallah et al. 2016, Wendt et al. 2015, 2018).

Tereancistrum parvus has been documented from a broad range of anostomid hosts, including L. fasciatus, L. friderici, L. lacustris (Amaral Campos, 1945), M. macrocephalus (Garavello & Britski, 1988), M. obtusidens, S. borelli, and S. nasutus (Guidelli et al. 2006, Takemoto et al. 2009, Karling et al. 2014, Wendt et al. 2015, 2018, Zago et al. 2017, Martins et al. 2017a, 2017b, Negreiros et al. 2021).

Tereancistrum toksonum, previously known from P. lineatus and P. nigricans, is now reported from P. brevis (a new host record). Similarly, T. pirassununguensis, initially described from P. lineatus, is now reported from P. nigricans and P. brevis. Tereancistrum curimba is also recorded from P. brevis, P. nigricans, and P. lineatus, expanding its known host range within Prochilodus.

Regarding recently described species, T. ancistrum is reported here parasitizing P. brevis (type-host), P. nigricans, and P. lineatus (two new host records), while T. spiralocirrum and T. kritskyi are reported from P. nigricans (a new host for these species). Finally, the discovery of T. kerri in B. pesu further supports the specificity of this species to the genus Brycon, as previously observed in other congeners.

ACKNOWLEDGEMENTS

We are grateful to Priscila R.P. Bernarde (Laboratório de Helmintos Parasitos de Peixes, Instituto Oswaldo Cruz, Rio de Janeiro, Brazil) for collecting and preparing helminth samples from DNOCS analyzed in this study. We thank Walter Boeger (Universidade Federal do Paraná, Brazil) for the illustrations of the haptoral parts and copulatory complex of T. ancistrum.

LITERATURE CITED

• Abdallah VD, Azevedo RK, Alves KGD, Camargo ADA, Vieira DHMD, Silva RJ (2016) The morphology of Tereancistrum paranaensis (Dactylogyridae) infecting Schizodon intermedius, with a key to the species. Neotropical Helminthology 10(1): 5-12.
• Andrade SMS, Malta JCO (2006) Parasite fauna monitoring of matrinxã Brycon amazonicus (Spix & Agassiz, 1829) raised in an intensive husbandry system in a stream channel in the state of Amazonas, Brazil. Brazilian Journal of Biology 66: 1123-1132. https://doi.org/10.1590/S1519-69842006000600020
  » https://doi.org/10.1590/S1519-69842006000600020
• Arévalo EG, Morey GAM, Malta JDO (2018) Parasitic fauna of Prochilodus nigricans (Prochilodontidae) from Brazilian Amazon floodplain lakes. Biota Amazônia 8(1): 19-21. https://doi.org/10.18561/2179-5746/biotaamazonia.v8n1p19-21
  » https://doi.org/10.18561/2179-5746/biotaamazonia.v8n1p19-21
• Arruda PS, Ferreira DC, Oliveira C, Venere PC (2019) DNA barcoding reveals high levels of divergence among mitochondrial lineages of Brycon (Characiformes, Bryconidae). Genes 10(9): 639. https://doi.org/10.3390/genes10090639
  » https://doi.org/10.3390/genes10090639
• Barroca TM, Arantes FP, Magalhães BF, Siqueira FF, Horta CC, et al. (2012) Genetic diversity and population structure of Prochilodus costatus and Prochilodus argenteus preceding weir construction in the Paraopeba River, São Francisco River Basin, Minas Gerais, Brazil. Open Journal of Genetics 2(2): 121. https://doi.org/10.4236/ojgen.2012.22017
  » https://doi.org/10.4236/ojgen.2012.22017
• Bonilla-Castillo CA, Córdoba EA, Gómez G, Duponchelle F (2018) Population dynamics of Prochilodus nigricans (Characiformes: Prochilodontidae) in the Putumayo River. Neotropical Ichthyology 16(2): e170139. https://doi.org/10.1590/1982-0224-20170139
  » https://doi.org/10.1590/1982-0224-20170139
• Cepeda PB, Ceccarelli PS, Luque JL (2012) A new species of Tereancistrum (Monogenea, Dactylogyridae) parasitic on Prochilodus lineatus (Valenciennes, 1837) (Characiformes) from Mogi Guaçu River, Brazil. Neotropical Helminthology 6(2): 205-210.
• Cohen SC, Justo MCN, Kohn A (2013) South American Monogenoidea parasites of fishes, amphibians and reptiles. Oficina de Livros, Rio de Janeiro, 663 pp.
• Dias KGA, Vieira DHMD, Camargo ADA, Silva RD, Azevedo RD, Abdallah VD (2017) Diversity of monogeneans parasites from Characiformes fishes in the Batalha River and Peixe’s River, State of São Paulo, Brazil. Neotropical Helminthology 11(2): 317-330.
• Guidelli G, Tavechio WLG, Takemoto RM, Pavanelli GC (2006) Fauna parasitária de Leporinus lacustris e Leporinus friderici (Characiformes, Anostomidae) da planície de inundação do alto rio Paraná, Brasil. Acta Scientiarum, Biological Sciences 28(3): 281-290.
• Hasuike WT, Scorsim B, Arjona IS, Amaral RB, Damacena-Silva L, et al. (2025) Morphology and molecular characterization of a new species of Tereancistrum parasite from the gills of Brycon nattereri Journal of Helminthology 99: e32. https://doi.org/10.1017/S0022149X25000148
  » https://doi.org/10.1017/S0022149X25000148
• Karling LC, Lopes LPC, Takemoto RM, Pavanelli GC (2014) New species of Tereancistrum (Dactylogyridae) monogenean parasites of Schizodon borellii (Characiformes, Anostomidae) from Brazil, and emended diagnosis for T. parvus Acta Scientiarum, Biological Sciences 36(3): 365-369. https://doi.org/10.4025/actascibiolsci.v36i3.20216
  » https://doi.org/10.4025/actascibiolsci.v36i3.20216
• Kritsky DC, Thatcher VE, Kayton RJ (1980) Neotropical Monogenoidea. 3. Five new species from South America with the proposal of Tereancistrum gen. n. and Trinibaculum gen. n. (Dactylogyridae: Ancyrocephalinae). Acta Amazonica 10(2): 411-417. https://doi.org/10.1590/1809-43921980102411
  » https://doi.org/10.1590/1809-43921980102411
• Lehun AL, Hasuike WT, Silva JOS, Ciccheto JRM, Michelan G, et al. (2020) Checklist of parasites in fish from the upper Paraná River floodplain: an update. Revista Brasileira de Parasitologia Veterinária 29: e008720. https://doi.org/10.1590/S1984-29612020066
  » https://doi.org/10.1590/S1984-29612020066
• Leite LAR, Pelegrini LS, Agostinho BN, Azevedo RKD, Abdallah VD (2018) Biodiversity of the metazoan parasites of Prochilodus lineatus (Valenciennes, 1837) (Characiformes: Prochilodontidae) in anthropized environments from the Batalha River, São Paulo State, Brazil. Biota Neotropica 18: e20170422. https://doi.org/10.1590/1676-0611-BN-2017-0422
  » https://doi.org/10.1590/1676-0611-BN-2017-0422
• Leite LAR, Pelegrini LS, Azevedo RKD, Abdallah VD (2020) A new species of Tereancistrum (Monogenea: Dactylogyridae), parasite of Prochilodus lineatus (Characiformes: Prochilodontidae) from southeast Brazil. Revista Brasileira de Parasitologia Veterinária 29: e017019. https://doi.org/10.1590/S1984-29612020024
  » https://doi.org/10.1590/S1984-29612020024
• Lizama MDLAP, Takemoto RM, Pavanelli GC (2004) New species of Tereancistrum Kritsky, Thatcher & Kayton, 1980 (Monogenea: Dactylogyridae: Ancyrocephalinae) from the gills of Prochilodus lineatus (Osteichthyes: Prochilodontidae) from the upper Paraná River floodplain, Brazil. Systematic Parasitology 57: 45-49. https://doi.org/10.1023/B:SYPA.0000010684.67784.6e
  » https://doi.org/10.1023/B:SYPA.0000010684.67784.6e
• Lopes JT, Pinheiro JPS, Nunes LT, Pinheiro RRR, Souza MEM, et al. (2014) Avaliação de diferentes crioprotetores e taxas de diluição na criopreservação seminal de Prochilodus brevis Revista Brasileira de Reprodução Animal 38(3): 170-175.
• Martins WMO, Justo MCN, Cárdenas MQ, Cohen SC (2017a) Seasonality of parasitic helminths of Leporinus macrocephalus and their parasitism rates in farming systems in the Amazon. Revista Brasileira de Parasitologia Veterinária 26(4): 419-426. https://doi.org/10.1590/S1984-29612017062
  » https://doi.org/10.1590/S1984-29612017062
• Martins WMO, Justo MC, Cárdenas MQ, Cohen SC (2017b) Metazoan parasite communities of Leporinus macrocephalus (Characiformes: Anostomidae) in cultivation systems in the western Amazon, Brazil. Acta Amazonica 47(4): 301-310. https://doi.org/10.1590/1809-4392201701243
  » https://doi.org/10.1590/1809-4392201701243
• Moreira J, Scholz T, Luque JL (2016) A new species of Diaphorocleidus (Monogenea: Ancyrocephalinae) from the gills of Argonectes robertsi (Characiformes) and new records of dactylogyrids parasitic on fishes from the Xingu River, Amazon Basin, Brazil. Zoologia 33(4): e20160022. https://doi.org/10.1590/S1984-4689zool-20160022
  » https://doi.org/10.1590/S1984-4689zool-20160022
• Morey GAM, Rojas CAT, Chu LAR, Arellano HS, Figeroa GSC (2023) Species of Monogenoidea from fish species used in aquaculture in the Peruvian Amazonia. Aquaculture 563: 738947. https://doi.org/10.1016/j.aquaculture.2022.738947
  » https://doi.org/10.1016/j.aquaculture.2022.738947
• Negreiros LP, Neves LR, Tavares-Dias M (2021) Parasites in Leporinus macrocephalus (Anostomidae) of four fish farms from the western Amazon (Brazil). Anais da Academia Brasileira de Ciências 93: e20190988. https://doi.org/10.1590/0001-3765202120190988
  » https://doi.org/10.1590/0001-3765202120190988
• Ninhaus-Silveira A, Foresti F, Azevedo A (2006) Structural and ultrastructural analysis of embryonic development of Prochilodus lineatus (Valenciennes, 1836) (Characiforme; Prochilodontidae). Zygote 14(3): 217-229. https://doi.org/10.1017/S096719940600373X
  » https://doi.org/10.1017/S096719940600373X
• Panarari-Antunes RS, Prioli AJ, Prioli SMAP, Júlio Jr HF, Agostinho CS, Prioli LM (2008) Molecular variability in Brycon cf. pesu Müller and Troschel, 1845 (Characiformes: Characidae) from the Araguaia-Tocantins basin. Genetics and Molecular Research 9(2): 674-684.
• Piña LH, Flores APPG, Paima EGP, Morey GAM (2017) Monogeneos parásitos de Prochilodus nigricans (Characiformes: Prochilodontidae) provenientes del medio natural y de un estanque de cultivo en la Amazonía Peruana. Folia Amazónica 26(2): 167-174. https://doi.org/10.24841/fa.v26i2.431
  » https://doi.org/10.24841/fa.v26i2.431
• Silva RA, Melo HP, Takemoto RM, Oliveira DU, Meneguetti DUO, Virgilio LR (2023) Monogeneans of Prochilodus nigricans (Prochilodontidae) in the southwestern Amazon. Acta Brasiliensis 7(3): 85-93. https://doi.org/10.22571/2526-4338656
  » https://doi.org/10.22571/2526-4338656
• Sousa BO, Oliveira MS, Tavares-Dias M (2019) Community structure of metazoan parasites in Hemibrycon surinamensis (Characidae) from the Matapi River in the State of Amapá, Brazil. Anais da Academia Brasileira de Ciências 91(2): e20180393. https://doi.org/10.1590/0001-3765201920180393
  » https://doi.org/10.1590/0001-3765201920180393
• Takemoto RM, Pavanelli GC, Lizama MDLA, Lacerda ACF, Yamada, FH, et al. (2009) Diversity of parasites of fish from the Upper Paraná River floodplain, Brazil. Brazilian Journal of Biology 69: 691-705. https://doi.org/10.1590/S1519-69842009000300023
  » https://doi.org/10.1590/S1519-69842009000300023
• Wendt EW, Monteiro CM, Amato SB (2015) New data on Tereancistrum parvus Kritsky et al. and T. paranaensis Karling et al. (Monogenea: Dactylogyridae) from Leporinus obtusidens Valenciennes (Characiformes: Anostomidae) from Lake Guaíba, southern Brazil. Neotropical Helminthology 9(2): 203-210.
• Wendt EW, Monteiro CM, Amato SB (2018) Helminth fauna of Megaleporinus obtusidens (Characiformes: Anostomidae) from Lake Guaíba: analysis of the parasite community. Parasitology Research 117: 2445-2456. https://doi.org/10.1007/s00436-018-5933-4
  » https://doi.org/10.1007/s00436-018-5933-4
• Yamada PDOF, Sousa WBB, Ebert MB, Diniz MFBG, Tavares-Dias M, et al. (2025) Integrative Taxonomy of Tereancistrum spp. (Monopisthocotyla: Dactylogyridae) Parasites of the Gills of Freshwater Fishes from the Caatinga Domain, Brazil. Pathogens 14(5): 467. https://doi.org/10.3390/pathogens14050467
  » https://doi.org/10.3390/pathogens14050467
• Toledo-Piza M, Baena EG, Dagosta FCP, Menezes NA, Ândrade M, et al. (2024) Checklist of the species of the Order Characiformes (Teleostei: Ostariophysi). Neotropical Ichthyology 22(1): e230086. https://doi.org/10.1590/1982-0224-2023-0086
  » https://doi.org/10.1590/1982-0224-2023-0086
• Zago AC, Yamada FH, Franceschini L, Bongiovani MF, Yamada PO, Silva RJ (2017) A new species of Tereancistrum (Monogenea, Dactylogyridae) from the gills of three Leporinus species (Characiformes, Anostomidae) and a revised description of Tereancistrum parvus Anais da Academia Brasileira de Ciências 89: 1121-1131. https://doi.org/10.1590/0001-3765201720160628
  » https://doi.org/10.1590/0001-3765201720160628

ADDITIONAL NOTES

• ZooBank register
  https://zoobank.org/C6E18D35-86E3-4A69-B650-C5F2C1E9C08B
• Data Availability Statement
  Datasets generated or analyzed in this study are available from the corresponding author on reasonable request.
• Funding
  This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, Finance Code 001).
• Ethical Statement
  This study did not involve live vertebrate animals and therefore did not require approval by an ethics committee. Field activities were conducted under collection permits issued by Biodiversity Authorization and Information System (SISBIO permit no. 69275-1; 44093-7).
• AI Statement
  No artificial intelligence tools were used in the preparation of this manuscript.
• How to cite this article
  Fontes JR, Freitas AJB, Justo MCN, Martins WMO, Bezerra CAM, Viana DC, Cohen SC (2026) New records and data of Tereancistrum spp. (Monogenoidea: Dactylogyridae) parasites of Characiformes from different localities in Brazil. Zoologia 43: e25060. https://doi.org/10.1590/S1984-4689.v43.e25060
• Published by
  Sociedade Brasileira de Zoologia at Scientific Electronic Library Online - https://www.scielo.br/zool

Edited by

• Editorial responsibility
  Walter A.P. Boeger

Data availability

Datasets generated or analyzed in this study are available from the corresponding author on reasonable request.

Publication Dates

• Publication in this collection
  12 June 2026
• Date of issue
  2026

History

• Received
  08 Oct 2025
• Accepted
  17 Jan 2026