Abstract:

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. 2021FRICKE, R., ESCHMEYER, W.N. & VAN DER LAAN, R. 2021. Catalog of fishes: genera, species, references. <http://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatmain.asp> (accessed 11 Jun 2021).
http://researcharchive.calacademy.org/re... ). Loricariids usually harbor oogyrodactylids (Harris 1983HARRIS, P.D. 1983. The morphology and life-cycle of the oviparous Oogyrodactylus farlowellae gen. et sp.nov. (Monogenea, Gyrodactylidea). Parasitol. 87:405-420. , Boeger et al. 2021BOEGER, A.B., KRITSKY, D.C., PATELLA, L. & BUENO-SILVA, M. 2021. Phylogenetic status and historical origins of the oviparous and viviparous gyrodactylids (Monogenoidea, Gyrodactylidea). Zool. Scr. 50:112-124.), although they can also concomitantly harbor species of gyrodactylids (Vianna & Boeger 2019VIANNA, R.T. & BOEGER, W.A. 2019. Neotropical Monogenoidea. 60. Two new species of Gyrodactylus (Monogenoidea: Gyrodactylidae) from the armored-catfish, Pareiorhaphis parmula Pereira (Loricariidae) and from the cascarudo, Callichthys callichthys (Linnaeus) (Callichthyidae) from Brazil. Zootaxa. 4551:87-93. ).

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, 2007KRITSKY, D.C., VIANNA, R.T. & BOEGER, W.A. 2007. Neotropical Monogenoidea. 50. Oviparous gyrodactylids from loricariid and pimelodid catfishes in Brazil, with the proposal of Phanerothecioides n. g., Onychogyrodactylus n. g. and Aglaiogyrodactylus n. g. (Polyonchoinea: Gyrodactylidea). Syst. Parasitol . 66:1-34. found in Pseudoplatystoma fasciatum (Linnaeus) (Kritsky et al. 2007KRITSKY, D.C., VIANNA, R.T. & BOEGER, W.A. 2007. Neotropical Monogenoidea. 50. Oviparous gyrodactylids from loricariid and pimelodid catfishes in Brazil, with the proposal of Phanerothecioides n. g., Onychogyrodactylus n. g. and Aglaiogyrodactylus n. g. (Polyonchoinea: Gyrodactylidea). Syst. Parasitol . 66:1-34. ), and Phanerothecium caballeroi Kritsky & Thatcher, 1977 on Zungaro zungaro (Humboldt, 1821) (Kritsky & Thatcher 1977KRITSKY, D.C. & THATCHER, V.E. 1977. Phanerothecium gen. nov. and Fundulotrema gen. nov. Two new genera of viviparous Monogenoidea (Gyrodactylidae), with a description of P. caballeroi sp. nov. and a key to the subfamilies and genera of the family. Excerta Parasitológica en memoria del doctor Eduardo Caballero y Caballero, Instituto de Biologie (Mexico), Publicaciones Especiales. 4: 53−60.).

Eight genera of oogyrodactylids are known: Aglaiogyrodactylus Kritsky, Vianna & Boeger, 2007KRITSKY, D.C., VIANNA, R.T. & BOEGER, W.A. 2007. Neotropical Monogenoidea. 50. Oviparous gyrodactylids from loricariid and pimelodid catfishes in Brazil, with the proposal of Phanerothecioides n. g., Onychogyrodactylus n. g. and Aglaiogyrodactylus n. g. (Polyonchoinea: Gyrodactylidea). Syst. Parasitol . 66:1-34. (8 species); Atopogyrodactylus Kritsky, Boeger & Patella, 2020KRITSKY, D.C., BOEGER, W.A. & PATELLA, L. 2020. Neotropical Monogenoidea. 63. Atopogyrodactylus praecipuus gen. et sp. n. (Gyrodactylidae), an oviparous gyrodactylid from the external surface of a bristlenose catfish Ancistrus sp. (Siluriformes: Loricariidae) from the Ronônian Amazon, Brazil. Zootaxa. 4732(1):169-176. (1); Hyperopletes Boeger, Kritsky & Belmont-Jégu, 1994BOEGER, W.A., KRITSKY, D.C. & BELMONT-JÉGU, E. 1994. Neotropical Monogenoidea. 20. Two species of oviparous Gyrodactylidea (Polynchoinea) from Loricariid catfishes (Siluriformes) in Brazil and the phylogenetic status of Oogyrodactylidae Harris, 1983. J. Helminthol. Soc. Wash. 61(1): 34-44. (1); Nothogyrodactylus Kritsky & Boeger, 1991KRITSKY, D.C. & BOEGER, W.A. 1991. Noetropical Monogenoidea. 16. New species of oviparous Gyrodactylidea with proposal of Nothogyrodactylus gen. n. (Oogyrodactylidae). J. Helminthol. Soc. Wash. 58(1): 7-15. (3); Onychogyrodactylus Kritsky, Vianna & Boeger, 2007KRITSKY, D.C., VIANNA, R.T. & BOEGER, W.A. 2007. Neotropical Monogenoidea. 50. Oviparous gyrodactylids from loricariid and pimelodid catfishes in Brazil, with the proposal of Phanerothecioides n. g., Onychogyrodactylus n. g. and Aglaiogyrodactylus n. g. (Polyonchoinea: Gyrodactylidea). Syst. Parasitol . 66:1-34. (2); Oogyrodactylus Harris, 1983HARRIS, P.D. 1983. The morphology and life-cycle of the oviparous Oogyrodactylus farlowellae gen. et sp.nov. (Monogenea, Gyrodactylidea). Parasitol. 87:405-420. (1); Phanerothecioides Kritsky, Vianna & Boeger, 2007KRITSKY, D.C., VIANNA, R.T. & BOEGER, W.A. 2007. Neotropical Monogenoidea. 50. Oviparous gyrodactylids from loricariid and pimelodid catfishes in Brazil, with the proposal of Phanerothecioides n. g., Onychogyrodactylus n. g. and Aglaiogyrodactylus n. g. (Polyonchoinea: Gyrodactylidea). Syst. Parasitol . 66:1-34. (1); and Phanerothecium Kritsky & Thatcher, 1977KRITSKY, D.C. & THATCHER, V.E. 1977. Phanerothecium gen. nov. and Fundulotrema gen. nov. Two new genera of viviparous Monogenoidea (Gyrodactylidae), with a description of P. caballeroi sp. nov. and a key to the subfamilies and genera of the family. Excerta Parasitológica en memoria del doctor Eduardo Caballero y Caballero, Instituto de Biologie (Mexico), Publicaciones Especiales. 4: 53−60. (6) (Kritsky & Thatcher 1977HARRIS, P.D. 1983. The morphology and life-cycle of the oviparous Oogyrodactylus farlowellae gen. et sp.nov. (Monogenea, Gyrodactylidea). Parasitol. 87:405-420. , Harris 1983HARRIS, P.D. 1983. The morphology and life-cycle of the oviparous Oogyrodactylus farlowellae gen. et sp.nov. (Monogenea, Gyrodactylidea). Parasitol. 87:405-420. , Kritsky & Boeger 1991KRITSKY, D.C. & BOEGER, W.A. 1991. Noetropical Monogenoidea. 16. New species of oviparous Gyrodactylidea with proposal of Nothogyrodactylus gen. n. (Oogyrodactylidae). J. Helminthol. Soc. Wash. 58(1): 7-15. , Boeger et al. 1994BOEGER, W.A., KRITSKY, D.C. & BELMONT-JÉGU, E. 1994. Neotropical Monogenoidea. 20. Two species of oviparous Gyrodactylidea (Polynchoinea) from Loricariid catfishes (Siluriformes) in Brazil and the phylogenetic status of Oogyrodactylidae Harris, 1983. J. Helminthol. Soc. Wash. 61(1): 34-44. , Kritsky et al. 2007KRITSKY, D.C., BOEGER, W.A. & PATELLA, L. 2020. Neotropical Monogenoidea. 63. Atopogyrodactylus praecipuus gen. et sp. n. (Gyrodactylidae), an oviparous gyrodactylid from the external surface of a bristlenose catfish Ancistrus sp. (Siluriformes: Loricariidae) from the Ronônian Amazon, Brazil. Zootaxa. 4732(1):169-176. , 2020KRITSKY, D.C., BOEGER, W.A. & PATELLA, L. 2020. Neotropical Monogenoidea. 63. Atopogyrodactylus praecipuus gen. et sp. n. (Gyrodactylidae), an oviparous gyrodactylid from the external surface of a bristlenose catfish Ancistrus sp. (Siluriformes: Loricariidae) from the Ronônian Amazon, Brazil. Zootaxa. 4732(1):169-176. ).

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. 2007KRITSKY, D.C., VIANNA, R.T. & BOEGER, W.A. 2007. Neotropical Monogenoidea. 50. Oviparous gyrodactylids from loricariid and pimelodid catfishes in Brazil, with the proposal of Phanerothecioides n. g., Onychogyrodactylus n. g. and Aglaiogyrodactylus n. g. (Polyonchoinea: Gyrodactylidea). Syst. Parasitol . 66:1-34. ). Phanerothecium caballeroi Kritsky & Thatcher, 1977KRITSKY, D.C. & THATCHER, V.E. 1977. Phanerothecium gen. nov. and Fundulotrema gen. nov. Two new genera of viviparous Monogenoidea (Gyrodactylidae), with a description of P. caballeroi sp. nov. and a key to the subfamilies and genera of the family. Excerta Parasitológica en memoria del doctor Eduardo Caballero y Caballero, Instituto de Biologie (Mexico), Publicaciones Especiales. 4: 53−60. was described in Z. zungaro (Pimelodidae) from Colombia, while the remaining species are from Brazil: Phanerothecium deiropedeum Kritsky, Vianna & Boeger, 2007KRITSKY, D.C., VIANNA, R.T. & BOEGER, W.A. 2007. Neotropical Monogenoidea. 50. Oviparous gyrodactylids from loricariid and pimelodid catfishes in Brazil, with the proposal of Phanerothecioides n. g., Onychogyrodactylus n. g. and Aglaiogyrodactylus n. g. (Polyonchoinea: Gyrodactylidea). Syst. Parasitol . 66:1-34. in Hypostomus sp.; Phanerothecium harrisi Kritsky & Boeger, 1991KRITSKY, D.C. & BOEGER, W.A. 1991. Noetropical Monogenoidea. 16. New species of oviparous Gyrodactylidea with proposal of Nothogyrodactylus gen. n. (Oogyrodactylidae). J. Helminthol. Soc. Wash. 58(1): 7-15. in Hypostomus plecostomus (Linnaeus, 1758) (= Plecostomus plecostomus Linnaeus, 1758); Phanerothecium spinatus Boeger, Kritsky & Belmont-Jégu, 1994 BOEGER, W.A., KRITSKY, D.C. & BELMONT-JÉGU, E. 1994. Neotropical Monogenoidea. 20. Two species of oviparous Gyrodactylidea (Polynchoinea) from Loricariid catfishes (Siluriformes) in Brazil and the phylogenetic status of Oogyrodactylidae Harris, 1983. J. Helminthol. Soc. Wash. 61(1): 34-44. (= P. spinatum, see Kritsky et al., 2007KRITSKY, D.C., VIANNA, R.T. & BOEGER, W.A. 2007. Neotropical Monogenoidea. 50. Oviparous gyrodactylids from loricariid and pimelodid catfishes in Brazil, with the proposal of Phanerothecioides n. g., Onychogyrodactylus n. g. and Aglaiogyrodactylus n. g. (Polyonchoinea: Gyrodactylidea). Syst. Parasitol . 66:1-34. ) in Hypostomus punctatus Valenciennes, 1840; Phanerothecium spinatoides Kritsky, Vianna & Boeger, 2007KRITSKY, D.C., VIANNA, R.T. & BOEGER, W.A. 2007. Neotropical Monogenoidea. 50. Oviparous gyrodactylids from loricariid and pimelodid catfishes in Brazil, with the proposal of Phanerothecioides n. g., Onychogyrodactylus n. g. and Aglaiogyrodactylus n. g. (Polyonchoinea: Gyrodactylidea). Syst. Parasitol . 66:1-34. in Hypostomus sp. 7 and sp. 9.; and Phanerothecium spinulatum Kritsky, Vianna & Boeger, 2007KRITSKY, D.C., VIANNA, R.T. & BOEGER, W.A. 2007. Neotropical Monogenoidea. 50. Oviparous gyrodactylids from loricariid and pimelodid catfishes in Brazil, with the proposal of Phanerothecioides n. g., Onychogyrodactylus n. g. and Aglaiogyrodactylus n. g. (Polyonchoinea: Gyrodactylidea). Syst. Parasitol . 66:1-34. in Hypostomus sp. (Kritsky & Boeger 1991KRITSKY, D.C. & BOEGER, W.A. 1991. Noetropical Monogenoidea. 16. New species of oviparous Gyrodactylidea with proposal of Nothogyrodactylus gen. n. (Oogyrodactylidae). J. Helminthol. Soc. Wash. 58(1): 7-15. , Boeger et al. 1994BOEGER, W.A., KRITSKY, D.C. & BELMONT-JÉGU, E. 1994. Neotropical Monogenoidea. 20. Two species of oviparous Gyrodactylidea (Polynchoinea) from Loricariid catfishes (Siluriformes) in Brazil and the phylogenetic status of Oogyrodactylidae Harris, 1983. J. Helminthol. Soc. Wash. 61(1): 34-44. , Kritsky et al. 2007KRITSKY, D.C., VIANNA, R.T. & BOEGER, W.A. 2007. Neotropical Monogenoidea. 50. Oviparous gyrodactylids from loricariid and pimelodid catfishes in Brazil, with the proposal of Phanerothecioides n. g., Onychogyrodactylus n. g. and Aglaiogyrodactylus n. g. (Polyonchoinea: Gyrodactylidea). Syst. Parasitol . 66:1-34. ).

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 1979HUMASON, G.L. 1979. Animal Tissue Techniques. Freeman and Company, San Francisco.). 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, 1977KRITSKY, D.C. & THATCHER, V.E. 1977. Phanerothecium gen. nov. and Fundulotrema gen. nov. Two new genera of viviparous Monogenoidea (Gyrodactylidae), with a description of P. caballeroi sp. nov. and a key to the subfamilies and genera of the family. Excerta Parasitológica en memoria del doctor Eduardo Caballero y Caballero, Instituto de Biologie (Mexico), Publicaciones Especiales. 4: 53−60.

Phanerothecium macrosomum n. sp.

(Figures 1, 2)

Figure 1
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.

Figure 2
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.

Discussion

Oogyrodactylidae was proposed by Harris (1983)HARRIS, P.D. 1983. The morphology and life-cycle of the oviparous Oogyrodactylus farlowellae gen. et sp.nov. (Monogenea, Gyrodactylidea). Parasitol. 87:405-420. to accommodate Oogyrodacytlus farlowellae Harris, 1983 parasitic of Farlowella amazonum (Günther, 1864) (Loricariidae) and Phanerothecium caballeroi Kritsky & Thatcher, 1977KRITSKY, D.C. & THATCHER, V.E. 1977. Phanerothecium gen. nov. and Fundulotrema gen. nov. Two new genera of viviparous Monogenoidea (Gyrodactylidae), with a description of P. caballeroi sp. nov. and a key to the subfamilies and genera of the family. Excerta Parasitológica en memoria del doctor Eduardo Caballero y Caballero, Instituto de Biologie (Mexico), Publicaciones Especiales. 4: 53−60., in Zungaro zungaro (Pimelodidae). Subsequently, Boeger & Kritsky (1993)BOEGER, W.A. & KRITSKY, D.C. 1993. Phylogeny and a revised classification of the Monogenoidea Bychowsky, 1937 (Platyhelminthes). Syst. Parasitol. 26: 1-32. 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. 2021BOEGER, A.B., KRITSKY, D.C., PATELLA, L. & BUENO-SILVA, M. 2021. Phylogenetic status and historical origins of the oviparous and viviparous gyrodactylids (Monogenoidea, Gyrodactylidea). Zool. Scr. 50:112-124.).

PhanerotheciumKritsky & Thatcher, 1977KRITSKY, D.C. & THATCHER, V.E. 1977. Phanerothecium gen. nov. and Fundulotrema gen. nov. Two new genera of viviparous Monogenoidea (Gyrodactylidae), with a description of P. caballeroi sp. nov. and a key to the subfamilies and genera of the family. Excerta Parasitológica en memoria del doctor Eduardo Caballero y Caballero, Instituto de Biologie (Mexico), Publicaciones Especiales. 4: 53−60. was considered monophyletic (Boeger et al. 2021BOEGER, A.B., KRITSKY, D.C., PATELLA, L. & BUENO-SILVA, M. 2021. Phylogenetic status and historical origins of the oviparous and viviparous gyrodactylids (Monogenoidea, Gyrodactylidea). Zool. Scr. 50:112-124.) and contains six species. In Brazil species of Phanerothecium were described only in Hypostomus Lacépède, 1803 hosts (Kritsky & Boeger 1991KRITSKY, D.C. & BOEGER, W.A. 1991. Noetropical Monogenoidea. 16. New species of oviparous Gyrodactylidea with proposal of Nothogyrodactylus gen. n. (Oogyrodactylidae). J. Helminthol. Soc. Wash. 58(1): 7-15. , Boeger, Kritsky & Belmont-Jégu 1994BOEGER, W.A., KRITSKY, D.C. & BELMONT-JÉGU, E. 1994. Neotropical Monogenoidea. 20. Two species of oviparous Gyrodactylidea (Polynchoinea) from Loricariid catfishes (Siluriformes) in Brazil and the phylogenetic status of Oogyrodactylidae Harris, 1983. J. Helminthol. Soc. Wash. 61(1): 34-44. , Kritsky, Vianna & Boeger 2007KRITSKY, D.C., VIANNA, R.T. & BOEGER, W.A. 2007. Neotropical Monogenoidea. 50. Oviparous gyrodactylids from loricariid and pimelodid catfishes in Brazil, with the proposal of Phanerothecioides n. g., Onychogyrodactylus n. g. and Aglaiogyrodactylus n. g. (Polyonchoinea: Gyrodactylidea). Syst. Parasitol . 66:1-34. ).

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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