Neotrop. Helminthol., 6(1), 2012

2012 Asociación Peruana de Helmintología e Invertebrados Afines (APHIA)

ISSN: 2218-6425 impreso / ISSN: 1995-1043 on line

ORIGINAL ARTICLE / ARTÍCULO ORIGINAL

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Amanda Nascimento Martins , Cláudia da Silveira São Sabas & Marilia de Carvalho Brasil-Sato

Prosthenhystera obesa (Diesing, 1850) (Digenea, Callodistomidae), parasitizes the gall bladder of

freshwater fish and was first found in Leporinus reinhardti Lütken, 1875 (Characiformes,

presented for the first time together with the data for L. reinhardti and P. pohli, two new hosts in the

Neotropical Region. The ecological descriptors of P. obesa were similar, i. e., they were low in all fish

of the São Francisco River and also in most fish from different hydrographic basins in accordance to

literature review. It is noteworthy that despite the considerable morphometric variability, pregnant

adult specimens of P. obesa occurred mainly in characin fish, especially ichthyophagous, top

Key words: Characidae - Digeneans - Leporinus reinhardti - Pimelodidae - Pimelodus pohli.

Suggested citation: Martins, AN, Sabas, CSS & Brasil-Sato, MC. 2012. Prosthenhystera obesa (Diesing, 1850) (Digenea,

Callodistomidae) in the São Francisco River Basin, Brazil: New host records and their ecological parameters. Neotropical

Helminthology, vol. 6, nº1, pp. 31- 41.

Palabras clave: Characidae - Digeneos - Leporinus reinhardti - Pimelodidae - Pimelodus pohli.

Prosthenhystera obesa (Diesing, 1850) (Digenea, Callodistomidae) parasita la vesícula biliar de los

peces de agua dulce y se encontró por primera vez en Leporinus reinhardti Lütken, 1875

(Characiformes, Anostomidae) y en Pimelodus pohli Ribeiro & Lucena, 2006 (Siluriformes,

pohli, dos nuevos hospederos de la región Neotropical. Los descriptores ecológicos de P. obesa fueron

similares, en otras palabras, fueron bajos en todos los peces del río São Francisco y también en la

mayoría de los peces de diferentes cuencas hidrográficas, de acuerdo con la revisión de la literatura. Se

destaca que a pesar de la variabilidad morfométrica de P. obesa, los especímenes adultos con huevos se

encuentran principalmente en los peces characidos, en particular en los ictiófagos, carnívoros

superiores de la cadena alimentaria.

Martins et al.

New host records of Prosthenhystera obesa

Diesing (1850) described Distomum obesum from

gall bladders of Salminus brevidens, Leporinus

Diesing (1855) information about D. obesum was

the same, but the localities and the date of

collection for these hosts were specified: S.

brevidens (= Salminus brasiliensis (Cuvier, 1816)

according Géry & Lauzanne (1990); cited as

“Salmo Nr. 9”, p. 9, and Salmini brevidentis too,

Fig. 11-13, in the Table III, p. 12), from Cuyaba

(State of Mato Grosso) in 26, 29 November 1824;

L. friderici (Bloch, 1794) from Mato Grosso (cited

as “Piaba” too, p. 9), in 30 October 1826, and X.

Prosthenhystera allocating D. obesum in it, as

described by Travassos (1922a) from specimens

collected of S. brevidens (= Salminus franciscanus

Lima & Britski, 2007 according to Lima & Britski

(2007)) from Lassance, Minas Gerais, in the São

Francisco River.

The morphometric variability of specimens of

Prosthenhystera obesa (Diesing, 1850) from

several hosts was presented by Kohn et al. (1997).

Despite this morphological investigation,

Plagiorchiida, after analysis of gene sequences of

smaller ribosomal subunits of nucleic acids and

because the cercariae have stylets to penetrate the

intermediate host. According to Olson et al.

(2003), representatives of Gorgoderoidea involve

a wide variety of hosts, that is, using aquatic

molluscs whose larvae can evolve in terrestrial

tetrapods in their cycles and can use terrestrial

larval characters of various species available

(Curran et al., 2006; Choudhury et al., 2007) with a

karyotype analysis of three species located in the

Allocreadiidae intramolluscan stage common in

the Palearctic region, suggested higher

evolutionary similarity between Allocreadiidae

and Callodistomidae and Gorgoderidae

(Gorgoderoidea) than Allocreadiidae and

Opecoelidae, currently placed in Allocreadioidea.

These authors pointed out that the karyotype

The unknown life cycle of the species in

freshwater fish, provided motivation for further

investigations on P. obesa parasitism in freshwater

fish. Besides the uniqueness of parasitism by these

hosts, according to Pavanelli et al. (1992),

pathology caused in fish would occur by gall

bladder rupture with reduced capacity for storage

of bile by the host and possible intake of hematin

pigments by the parasite.

According to the records P. obesa has a wide

distribution in Characiformes in Brazil:

Astyanax fasciatus (Cuvier, 1819) by Travassos &

Freitas (1941), Galeocharax humeralis

(Valenciennes, 1834) by Travassos & Kohn

(1965), Brycon sp., Cynopotamus amazonum

(Günther, 1868) and Caranx gibbosus (Linnaeus)

and Triurobrycon lundii Reinhardt by Kohn et al.

(1997), later nominal taxa not found in FishBase;

Cichlidae – Cichlasoma bimaculatum Linnaeus,

1758 by Travassos (1940); Anostomidae -

Leporinus sp. by Travassos (1922b), Leporinus

Several species of fish from the upper São

Francisco River, Minas Gerais, Brazil, had their

endoparasitic fauna recently investigated:

franciscanus by Brasil-Sato (2002), Myleus

micans (Lütken, 1875) by Brasil-Sato & Santos

Martins et al.

New host records of Prosthenhystera obesa

kelberi Kullander & Ferreira, 2006 by Santos

(2008); Prochilodontidae - Prochilodus argenteus

Spix & Agassiz, 1829 by Monteiro et al. (2009)

and Monteiro (2011); Acestrorhynchidae -

Acestrorhynchus lacustris (Lütken, 1875) and

Acestrorhynchus britskii Menezes, 1969 by Costa

bladder of yellow catfish, P. maculatus and

“dourado”, S. franciscanus. In this study, “piau-

três-pintas”, Leporinus reinhardti Lütken, 1875

(Characiformes, Anostomidae) and white catfish,

Pimelodus pohli Ribeiro & Lucena, 2006

(Siluriformes, Pimelodidae), are recorded as new

hosts of P. obesa, and the morphometry of parasite

specimens is shown for these hosts from the upper

São Francisco River. Noteworthy was the

occurrence of immature P. obesa specimens in

Leporinus reinhardti specimens were identified

according to Britski et al. (1988) and classified

according to Reis et al. (2003), while P. pohli

specimens were classified according to Ribeiro &

Lucena (2006). The synonymy among taxa listed

in parentheses and the nominal authorship of new

Fish Collection of the Museu de Zoologia at the

Universidade de São Paulo (MZUSP), São Paulo,

Martins et al.

New host records of Prosthenhystera obesa

Leporinus reinhardti and P. pohli are new hosts for

P. obesa, Digenea with Neotropical distribution. In

addition to these two hosts, P. obesa specimens had

previously been found in S. franciscanus (Brasil-

Sato, 2002, 2003) and in P. maculatus (Brasil-Sato

2003, Brasil-Sato & Pavanelli 2004), both hosts

were collected from P. maculatus – one specimen

per host. Prevalence was 1.2% and mean

abundance 0.01 ± 0.11. The morphometric data of

P. obesa are presented in Table 1.

Table 1 lists the measurements of P. obesa

specimens in Characiformes, L. reinhardti (one

specimen), new host record, and S. franciscanus

(three specimens) and in Siluriformes, P. pohli

(one specimen), new host record, and P. maculatus

(three specimens) in the upper São Francisco

River.

Leporinus reinhardti and P. pohli specimens were

classified as pregnant and immature, respectively.

and width and oral sucker) found in L. reinhardti

were lower than those shown by parasite

specimens of S. brevidens and S. maxillosus (= S.

brasiliensis) (Kohn et al., 1997) but were similar to

those of S. brasiliensis (= S. franciscanus) (Brasil-

to those of immature specimens found in P.

corruscans (Kohn et al., 1997). Measurements of

P. obesa in S. franciscanus were similar relative to

the other Characidae studied by Travassos (1922a)

and Kohn et al. (1997). Measurements of

specimens collected from P. maculatus were larger

than those from Pimelodus spp. recorded by Kohn

maculatus from the Paraná River.

The parasitic parameters were considered low,

even though among the characiform hosts,

habits, and analysis of stomach contents in fish in

this study showed that this species is opportunistic

presence of arthropod larvae and sediment were

observed in its stomach content. This species could

also act as a definitive host, but due to the immature

specimen found, it is not possible to state that.

As the life cycle of Callodistomidae remains

unknown (Bray, 2002; Cribb et al., 2002), the

evaluation of parasitism by P. obesa in freshwater

fish hosts may be an attempt to help elucidate the

possible cycle of these Digenea. Thus, taking into

consideration the measurements of specimens

previously reported in the literature (Kohn et al.,

are located in either Characidae or Anostomidae.

In the records of Siluriformes, the collected

specimens from pimelodid fishes often were

Prosthenhystera obesa specimens in fish showed

great variability in size (Pavanelli et al., 1992;

confirmed that for a long time it has been observed

that not only the size but the maturation of these

Digenea is affected among hosts of different

families. In some records, P. obesa specimens

collected in characids were smaller and immature

(and probably had less time to produce eggs in the

host), because according to the literature (op. cit.) it

was from this host family that the largest

specimens were collected and in addition, they

were usually pregnant. In anostomids, Kohn et al.

(1997) observed smaller specimens, but despite

this, they were pregnant, indicating a possibility of

Besides the level of development in relation to the

type of host, the fact that the specimens were found

single and pregnant specimens were found in the

gall bladder of Characiformes hosts. In this

situation, if they were solitary during all their

parasitism may be important to unveil the main

evolutionary path of the species in South American

lacustrine ecosystems. Research on whether this

path would be linked to be used by carnivorous

characiform hosts as a requirement to reach

maturity, or whether egg production by digeneans

would be dependent on sexual reproduction and the

Martins et al.

New host records of Prosthenhystera obesa

It is possible that the location of parasitism is a

controlling factor of parasitic intensity. Pavanelli

et al. (1992) state that P. obesa is relatively large in

relation to the organ it parasitizes, and as the

parasite uses bile of the gall bladder, an increase of

infection intensity could be harmful for both the

development to maturity of P. obesa in

Characiformes and absence of such a relationship

Our thanks to Yoshimi Sato, researcher at

CIRPA/CODEVASF, Três Marias, MG, and

CEMIG-GT/CODEVASF working arrangement

for providing logistical and material support; and

to Dr. Philip J. Scholl for English revision. Claudia

da Silveira São Sabas was supported by a student

fellowship from the Coordenação de

Aperfeiçoamento de Pessoal de Nível Superior

Albuquerque, MC. 2009. Taxonomia e aspectos

Helmintos

Bray, RA. 2002.

Britski, HA, Sato, Y & Rosa, ABS. 1988.

Bush, AO, Lafferty, JM & Shostak, AW. 1997.

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