A new species of Phanerothecium (Monogenea, Oogyrodactylidae), in Hypostomus regani (Loricariidae) from southeast BrazilAbstract:
A new species of Phanerothecium Kritsky & Thatcher, 1977 (Oogyrodactylidae Harris, 1983) is described from locariid fish from southeast Brazil. Phanerothecium macrosomum n. sp. (Oogyrodactylidae) is described from the body surface of Hypostomus regani (Ihering, 1905) (Loricariidae). It is characterized by an armed male copulatory organ containing spines of different size from proximal to distal extremity, short peduncle and robust haptor.
Keywords: Brazilian siluriforms; freshwater fish; Oogyrodactylidae; Batalha River; Neotropical region
Resumo:
Uma nova espécie de Phanerothecium Kritsky & Thatcher, 1977 (Oogyrodactylidae Harris, 1983) é descrita em peixes locariídeos do sudeste do Brasil. Phanerothecium macrosomum sp. n. (Oogyrodactylidae) é descrito da superfície corporal de Hypostomus regani (Ihering, 1905) (Loricariidae) e é caracterizado pela presença de órgão copulador masculino armado contendo espinhos de diferentes tamanhos da extremidade proximal à distal, pedúnculo curto e haptor robusto.
Palavras-chave: Siluriformes brasileiros; peixe de água doce; Oogyrodactylidae; rio Batalha; Região Neotropical
Introduction
Siluriformes Cuvier, 1816 is the most diverse group of fishes in South America and mainly in Brazil. Loricariidae Rafinesque, 1815 is one of the families included in this order and the second richest with 1192 valid species (Fricke et al. 2021). Loricariids usually harbor oogyrodactylids (Harris 1983, Boeger et al. 2021), although they can also concomitantly harbor species of gyrodactylids (Vianna & Boeger 2019).
There are 23 known species of oogyrodactylids all restricted to the Neotropical region and parasitizing loricariid and pimelodid fishes (Siluriformes). Oogyrodactylids were reported parasitizing pimelodid fishes, considered an accidental infestation, as Phanerothecioides agostinhoi Kritsky, Vianna & Boeger, 2007 found in Pseudoplatystoma fasciatum (Linnaeus) (Kritsky et al. 2007), and Phanerothecium caballeroi Kritsky & Thatcher, 1977 on Zungaro zungaro (Humboldt, 1821) (Kritsky & Thatcher 1977).
Eight genera of oogyrodactylids are known: Aglaiogyrodactylus Kritsky, Vianna & Boeger, 2007 (8 species); Atopogyrodactylus Kritsky, Boeger & Patella, 2020 (1); Hyperopletes Boeger, Kritsky & Belmont-Jégu, 1994 (1); Nothogyrodactylus Kritsky & Boeger, 1991 (3); Onychogyrodactylus Kritsky, Vianna & Boeger, 2007 (2); Oogyrodactylus Harris, 1983 (1); Phanerothecioides Kritsky, Vianna & Boeger, 2007 (1); and Phanerothecium Kritsky & Thatcher, 1977 (6) (Kritsky & Thatcher 1977, Harris 1983, Kritsky & Boeger 1991, Boeger et al. 1994, Kritsky et al. 2007, 2020).
Phanerothecium is characterized mainly for possessing vitelline follicles and ducts in reversed h-shaped, both absent in dextral pregermarial field; coiled, twisted copulatory organ spined (or not) inside of copulatory sac, eversible or with distal non-eversible sclerotized tube; uterus with heavy wall, containing from one-to-many eggs (sometimes empty) (Kritsky et al. 2007). Phanerothecium caballeroi Kritsky & Thatcher, 1977 was described in Z. zungaro (Pimelodidae) from Colombia, while the remaining species are from Brazil: Phanerothecium deiropedeum Kritsky, Vianna & Boeger, 2007 in Hypostomus sp.; Phanerothecium harrisi Kritsky & Boeger, 1991 in Hypostomus plecostomus (Linnaeus, 1758) (= Plecostomus plecostomus Linnaeus, 1758); Phanerothecium spinatus Boeger, Kritsky & Belmont-Jégu, 1994 (= P. spinatum, see Kritsky et al., 2007) in Hypostomus punctatus Valenciennes, 1840; Phanerothecium spinatoides Kritsky, Vianna & Boeger, 2007 in Hypostomus sp. 7 and sp. 9.; and Phanerothecium spinulatum Kritsky, Vianna & Boeger, 2007 in Hypostomus sp. (Kritsky & Boeger 1991, Boeger et al. 1994, Kritsky et al. 2007).
In this study a new species of Phanerothecium is described from the body surface of Hypostomus regani (Ihering, 1905) (Loricariidae) from southern Brazil.
Materials and Methods
Sixty specimens of the armored-catfish, Hypostomus regani (Loricariidae) (mean weight = 165.45 ± 77.75g and mean standard length = 17.72 ± 2.85cm), were collected from February 2014 to February 2016 in the Batalha River, Reginópolis municipality, State of São Paulo.
Fish were captured using nylon monofilament gillnets with different mesh sizes (sizes ranging from 20 to 100 mm internodes). The gillnets were placed on the slopes or near the river bottom at night and removed before dawn (10 hours exposure). Fish were removed from nets, anesthetized with eugenol solution (clove oil), and submitted to euthanasia through the physical method of medullary section, being immediately individualized in plastic bags and frozen for laboratory analysis. We observed that storing fish in plastic bags might have damaged the shape of some adults’ parasites, flattening the bodies of the specimens. Even so, it was possible to observe the anatomy and represent it.
Sampling was carried out according to guidelines of the scientific fishing license under the authorization of the Chico Mendes Institute of Biodiversity through the System of Authorization and Information on Biodiversity (authorization nº 40998-2). The research project was submitted to the Ethical Committee on Animal Use of the Centro Universitário Sagrado Coração (UNISAGRADO) (authorization nº 3353050417).
Specimens of oogyrodactylids were collected under a dissecting microscope, preserved individually in 70% ethanol, and mounted on a slide prepared with Gray & Wess mounting medium; others were stained with Gomori’s trichrome and mounted in Canada balsam (Humason 1979). Drawings were prepared with the aid of camera lucida on an Olympus BX51 microscope, equipped with phase contrast. Adult specimens were drawn from the side, as due to the size of the parasites and the form of conservation they were damaged. However, it is possible to identify and interpret the parasite anatomy. Measurements were made with ImageJ (NIH, Inc.) and are reported in micrometers (µm); the mean is followed by the range and sample size in parentheses (n). Measurements were taken by straight-line distances.
Type specimens were deposited in the helminthological collection of Museu de Zoologia da Universidade de São Paulo, São Paulo (MZUSP), Brazil, as presented in the respective descriptions.
Results
Phanerothecium Kritsky & Thatcher, 1977
Phanerothecium macrosomum n. sp.
Phanerothecium macrosomum n. sp. (Oogyrodactylidae) on the body surface of Hypostomus regani (Loricariidae), holotype. a. Wholemount mature adult, lateral view. b. MCO (male copulatory organ). showing larger spines in the proximal portion and smaller spines in the distal portion. c. Egg. d. Hook. e. Wholemount immature specimen, ventral view, flattened. f. Anchor. g. Complex of anchors, superficial bar.
Phanerothecium macrosomum n. sp. (Oogyrodactylidae) on the body surface of Hypostomus regani (Loricariidae). h. Wholemount immature specimen, ventral view. i. Egg. j-k. Haptor. l. Male copulatory organ complex. mco - male copulatory organ, cs - copulatory sac, sv - seminal vesicle. m. Partial view of haptor. mh - musculature of haptor
Type host: Hypostomus regani (Ihering, 1905) (Loricariidae).
Site of infection: Body surface.
Type locality: Batalha River (22° 06′ 35.2″S, 47° 49′ 12. 5″W), Reginópolis, São Paulo, Brazil, February 2014.
Prevalence and intensity: 11.7% and 3.3 ± 2.2 (7 parasitized hosts out of 60 analyzed).
Specimens deposited: MZUSP 8042-e (holotype), MZUSP 8042-a, MZUSP 8042-b, MZUSP 8042-c, MZUSP 8042-d, MZUSP 8042-f, MZUSP 8042-g, MZUSP 8042-h, MZUSP 8042-i, MZUSP 8042-j (paratypes).
Etymology: The specific name originates from Greek and refers to the strong and big body (macro = big; soma = body).
Description: Body 1509 (796-2098, n = 7) long, greatest body width at level of Mehlis’ gland 309 (125-422, n = 7) (Figure 1a); peduncle short in pre-adult and matures adult specimens (Figure 1a, (2h,). Unicellular cephalic glands, head organ conspicuous. Anterior pharyngeal bulb 96 (92-100, n = 2) diameter, from ovate to circular; posterior pharyngeal bulb 129 (120-137, n = 2) diameter, from ovate to circular. Testis observed only in immature specimens (Figure 1e, 2h), ovate, variable in size according to maturation; anterior seminal vesicle, elliptical, with thin wall; posterior seminal vesicle subspherical, bigger than anterior in pre-adults, with thick wall, reduced in adults (Figure 1b, 2l). Copulatory sac (Figure 2l) ovate, thick wall; male copulatory organ (MCO) tubular, muscular, inverted or everted (Figure 1b, (2l). MCO with spines of different sizes from proximal to distal portion (Figure 1b). Germarium not observed. Mehlis’ gland well developed; uterus containing up to 19-40 eggs; uterine pore dextroventral, a transverse or diagonal slit with thickened rim. Egg 183 (170-213, n = 4) long, egg filament about 1/6 total egg length, with slight proximal bilobate flare (Figure 1c, (2i); egg droplets not observed. Haptor 368 (249-439, n = 7) long, 370 (276-447, n = 4) wide, subrectangular (young specimens) (Figure 1e, (2j) to circular (pre-adults and adults) (Figure 1a, 2k), with a thick edge formed by dorsal layer and hooklets (Figure 1d, 2j, 2k). Ventral portion containing two very conspicuous muscular regions, lateral to anchor/bar complex, and due to striation appear to contain multiple papillae (Figure 2m). Anchor 385 (358-433, n = 3) long, with elongate superficial root, triangular and elongate deep root, slightly curved shaft and recurved point (Figure 1f, (1g, (2j, (2k). Superficial bar subrectangular 59 (51-66, n = 3) long; deep bar rod-shaped (Figure 1g, (2j). Hooks similar in shape and size, holocentric 34 (23-45, n = 2) long; hooklet 4 (n = 2) long, usually flexed ventrally, with short slightly recurved point, ventrally leaning shaft, globose heel and upright toe; shank tapers proximally to fine filament, with ventral keel near mid-length; FH (filament of hook) loop about 1/3 of shank length (Figure 1d).
Remarks. A comparison with other species of genus allows indicate P. macrosomum n. sp. as a new and the biggest species among all Phanerothecium species (Table 1). The new species is differentiated from the other congeneric species by presence of short peduncle; haptor subrectangular, containing strongly muscularized regions, antero-lateral to anchors; MCO armed with spines of different sizes from proximal to distal portion. Others three species of Phanerothecium presents armed MCO, P. spinatus, P. spinatoides and P. spinulatum and differ from P. macrosomum n. sp. by presence of spines of similar sizes and shapes.
Comparison of the measurements of Phanerothecium species. Values to P. caballeroi (forma minor/ forma major); values to P. harrisi (Kritsky et al. (2007)/ Kritsky & Boeger (1991)); values to P. spinatoides (from Hypostomus sp. 7/ from Hypostomus sp. 9). The values presented to measeruments gived are average.
Discussion
Oogyrodactylidae was proposed by Harris (1983) to accommodate Oogyrodacytlus farlowellae Harris, 1983 parasitic of Farlowella amazonum (Günther, 1864) (Loricariidae) and Phanerothecium caballeroi Kritsky & Thatcher, 1977, in Zungaro zungaro (Pimelodidae). Subsequently, Boeger & Kritsky (1993) consider Oogyrodactylidae synonymy of Gyrodactylidae due to the absence of synapomorphic features, thus uniting oviparous and viviparous species. Recently, through the use molecular data of 18S rDNA and COII (cytochrome oxidase II - mtDNA) Oogyrodactylidae (oviparous species) was reconsidered valid, separating this from species of Gyrodactylidae (viviparous species), thus both families were considered monophyletic and sister-groups (Boeger et al. 2021).
PhanerotheciumKritsky & Thatcher, 1977 was considered monophyletic (Boeger et al. 2021) and contains six species. In Brazil species of Phanerothecium were described only in Hypostomus Lacépède, 1803 hosts (Kritsky & Boeger 1991, Boeger, Kritsky & Belmont-Jégu 1994, Kritsky, Vianna & Boeger 2007).
Neither species of them Phanerothecium presents spines with different sizes on MCO as P. macrosomum n. sp. and the tubular MCO, muscular or sclerotized and unarmed was observed in P. caballeroi, P. harrisi and P. deiropedeum, while the muscular MCO, armed with diminutes spines and of the same size, were founded in P. spinatoides, P. spinulatum and P. spinatus.
The morphological features of P. macrosomum n. sp. as short peduncle, haptor and spines of MCO support the new species.
Acknowledgments
We would like to thank the São Paulo Research Foundation (FAPESP) for the research project grant of Vanessa D. Abdallah (2012/23655-0) and Rodney K. de Azevedo (2014/12862-0).
References
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Edited by
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Associate EditorJuan Schmitter-Soto
Publication Dates
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Publication in this collection
01 Aug 2022 -
Date of issue
2022
History
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Received
21 June 2021 -
Accepted
16 June 2022
