ISSN Versión impresa 2218-6425 ISSN Versión Electrónica 1995-1043

ORIGINAL ARTICLE / ARTÍCULO ORIGINAL

PARVAPROSTATUM SYNBRANCHI N. GEN. N. SP. (TREMATODA: DIPLOSTOMIDA), PARASITE

OF SWAMP-EEL SYNBRANCHUS MARMORATUS BLOCH, 1795 IN URUGUAY

PARVAPROSTATUM SYNBRANCHI N. GEN. N. SP. (TREMATODA: DIPLOSTOMIDA), PARÁSITO

DE LA ANGUILA SYNBRANCHUS MARMORATUS BLOCH, 1795 EN URUGUAY

1 Laboratorio de Fisiología y Reproducción de Peces (FREP), Facultad de Ciencias, Universidad de la Republica,

Montevideo, Uruguay. Renzo Vettorazzi, Iguá 4225, +59825258618, rvetto@fcien.edu.uy

2 Instituto de Investigaciones Pesqueras (IIP), Facultad de Veterinaria, Universidad de la Republica, Montevideo, Uruguay.

1 2 2

Renzo Vettorazzi Fernandez ; Maite Letamendía Tourne & Daniel Carnevia Guerrero

ABSTRACT

Keywords: Massoprostatinae – Massoprostatum – metacercaria – Parvaprostatum – parasite – progenetic – Sauce Lagoon – swamp-eel – Uruguay

The family Synbranchidae has a Neotropical distribution with parasite reports in Mexico, Brazil and

Argentina, evidencing the lack of studies regarding the parasitofauna of swamp-eels. Parasitological

examination through classic methods done on five swamp-eels (Synbranchus marmoratus Bloch, 1795)

captured in Sauce Lagoon in Uruguay, showed the presence of Massoprostatinae parasites, which were

stained and mounted through classical procedure, with Langeron's Carmine and Entellan, respectively.

The Subfamily Massoprostatinae is monotypic with Massoprostatum Yamaguti, 1958 as the only genus

and M. longum Caballero, 1948 as only species. To-date, it is only reported in crocodilians living in

Mexico and Columbia. Morphological and biometric comparisons of relevant characteristics for the

taxonomy of the family such as paraprostate size, hindbody and forebody ratio and vitellaria distribution,

show their correspondence to a new genus and species, hereby named Parvaprostatum synbranchi. The

lack of reports makes it difficult to conclude if Massoprostatinae is truly specific to crocodilians and thus,

we cannot ascertain if the present report in eels implies host-switching. Despite the possibility of the

parasites being progenetic metacercariae, conspicuous development of structures such as the tribocitic

and reproductive organs, the presence of food content and the fact that they were un-encysted and gravid,

make the specimens morphologically reliable for species identification. This new fish host and type

locality report emphasizes the need for further studies to understand the underlying lifecycle of

Massoprostatinae species.

Neotropical Helminthology

151

Neotropical Helminthology, 2019, 13(2), jul-dic:151-160.

ÓrganooficialdelaAsociaciónPeruanadeHelmintologíaeInvertebradosAfines(APHIA)

Lima-Perú

VersiónImpresa:ISSN2218-6425VersiónElectrónica:ISSN1995-1043

Volume13,Number2(jul-dec2019)

INTRODUCTION

152

RESUMEN

Palabras clave: Massoprostatinae – Massoprostatum – metacercaria – Parvaprostatum – parásito – progenético – Laguna del Sauce – anguila – Uruguay

La familia Synbranchidae presenta una distribución Neotropical con reportes parasitarios en Méjico,

Brasil y Argentina, lo cual evidencia la falta de estudios en cuanto a la parasitofauna de estas anguilas. La

inspección parasitológica clásica realizada en cinco anguilas (Synbranchus marmoratus Bloch, 1795)

capturadas en Laguna del Sauce en Uruguay, reveló la presencia de parásitos de la subfamilia

Massoprostatinae, los cuales fueron teñidos y montados mediante procedimientos convencionales, con

Carmín de Langeron y Entellan, respectivamente. La subfamilia Massoprostatinae es monotípica, siendo

Massoprostatum Yamaguti, 1958 su único género y M. longum Caballero, 1948 su única especie. A la

fecha, esta especie solo se ha reportado en cocodrilos en Méjico y Colombia. Comparaciones

morfológicas y biométricas de caracteres con relevancia taxonómica para la familia tales como el tamaño

de la paraprostata, relación del tramo anterior y posterior del cuerpo y la distribución de las glándulas

vitelarias, muestra que los ejemplares corresponden a un nuevo género y especie: Parvaprostatum

synbranchi. La falta de reportes dificulta concluir si Massoprostatinae es realmente específica para

cocodrilos y por lo tanto, no se puede aseverar si el presente reporte en anguilas implica un cambio de

hospedador. Mas allá de la posibilidad de que los parásitos correspondan a metacercarias progenéticas, el

desarrollo conspicuo de estructuras como el órgano tribocítico y los órganos reproductores, la presencia

de contenido alimenticio en los ciegos intestinales y el hecho de que se hallaron desenquistados y

grávidos, hace que los especímenes sean morfológicamente confiables para la identificación a nivel

específico. El reporte de un nuevo hospedador y una nueva localidad enfatizan la necesidad de estudios

que permitan entender los ciclos de vida subyacentes en especies de la subfamilia Massoprostatinae.

Maldonado & Aguilar-Aguilar, 2002 (Moravec et

al., 2002a), Gibsonnema ophisterni Moravec,

Salgado-Maldonado & Aguilar-Aguilar, 2002

(Moravec et al., 2002b) in Ophisternon

aenigmaticum Rosen & Greenwood, 1976; and

Argentina: Synbranchiella mabelae Arredondo,

Viera Alves & de Pertierra, 2017 (Arredondo et al.,

2017) in S. marmoratus. Considering the wide

Neotropical distribution of the swamp-eels,

knowledge of their parasitological fauna is

evidently scarce, given there is a lack of knowledge

from several countries in South America, one of

them being Uruguay.

We describe a new parasite genus and new species

of the family Proterodiplostomidae, found in the

marble swamp-eel Synbranchus marmoratus

Bloch, 1795 from a coastal lagoon in Uruguay.

Additionally, we propose slight changes to the

diagnosis of the subfamily Massoprostatinae,

considering that, in the light of our finding, the

rigidity of its description likely comes from a lack

of known diversity.

The swamp-eels (Synbranchidae) present a

Neotropical distribution, living in fresh-water,

lacustrine environments (Nelson et al., 2016). In

regards to the family's parasitological fauna,

reports exist for Brazil: Cyrilia gomesi (Neiva &

Pinto, 1926) Lainson, 1981 (Lainson & Canning,

1981), Trypanosoma bourouli (Neiva & Pinto,

1926) Lainson, 1981 (Lainson & Canning, 1981),

Cyrilia lignieresi Laveran, 1906 (Diniz et al.,

2002), Clinostomum sp. Leidy, 1856 (Erias et al.,

2010) and C. detruncatum Braun, 1899 (Locke et

al., 2015; Acosta et al., 2016) in Synbranchus

marmoratus Bloch, 1795; Mexico (Salgado-

Maldonado, 2008): Genarchella isabellae

Lamothe-Argumedo, 1977 (Kohn et al., 1990),

Pseudocapillaria ophisterni Moravec, Salgado-

Maldonado & Jimenez-Garcia, 2000 (Moravec et

al., 2000), Monticellia ophisterni de Chambrier &

Salgado-Maldonado, 2001 (Scholz et al., 2001),

Philometra ophisterni Moravec, Salgado-

Neotropical Helminthology, 2019, 13(2), jul-dic Vettorazzi Fernandez et al.

153

MATERIALS AND METHODS

Sampling of five (5) swamp-eels S. marmoratus

took place in Sauce Lagoon, Maldonado, Uruguay,

in May of 2019. The eels were taken to the

laboratory and euthanized with eugenol overdose

before a cervical and cephalic incision, under the

approval of the institutional Ethics Council of

Animal Experimentation, in compliance with the

AVMA international guidelines for fish euthanasia

(Leary et al., 2013). Autopsy on the specimens was

performed immediately after, removing the

visceral organs for parasitological inspection. The

parasites were removed manually and observed in

fresh condition to better describe body shape.

Afterwards, holotype and paratypes were fixated

under pressure with heat and formalin 10% and

stored in ethanol 70%. They were then stained with

Langeron's Carmine solution for 10-15 min

(following staining process through stereoscopic

microscope Nikon C-LEDS), dehydrated with

ethanol bathes of increasing concentration (10

minutes ethanol 70%, 10 minutes ethanol 80%, 10

minutes ethanol 95%, 10 minutes ethanol 100%)

and then permanently mounted in Entellan medium

between slide and coverslip.

The specimens were observed in Light Microscope

(Olympus BX50) and photos were taken with

adapted 318CU 3.2M CMOS camera and

M i c r o m e t r i c s S E P r e m i u m p r o g r a m .

Measurements were taken over the drawings with

regular rulers and then converted to micrometers

(µm), or alternatively with ruler grill installed into

the ocular of the microscope. Images taken with

Micrometrics SE Premium were also used for

measuring through the program ImageJ. Digital

drawings were performed with open software

GIMP2, based on the pictures taken or as a

summary of the structures seen in different

specimens. Exact Binomial Confidence Interval

(CI) and Bootstrap Cias-corrected and Accelerated

Confidence Interval (BCa) were calculated for the

Prevalence and the Mean Intensity respectively,

were using R Program packages Binom and

BootBCa correspondingly.

Holotype and paratypes were stored as an annex to

the Ichthyological Collection of the National

Museum of Natural History, Montevideo,

Uruguay, with access numbers MNHN 4213 and

RESULTS

MNHN 4214 (lot of 4 paratypes), respectively.

Ethic aspects

The authors point out that they fulfilled all national

and international ethical aspects.

Three (3) of the five (5) marble swamp-eels

analyzed were infected, with number of specimens

ranging from 5 to 62. The parasites were found

across the entirety of the celom, under and above

the mesenteries, un-encysted, associated with the

liver, the gonads and the outside of the gut. In one

case, parasite eggs were observed within the ovary

of the host.

Subclass Digenea

Superfamily Diplostomoidea

Family Proterodiplostomidae, Dubois 1936

Subfamily Massoprostatinae, Yamaguti 1958

Genero Parvaprostatum n. gen.

Body type elongate, bipartite without notable

constriction (Figure 1). Forebody length less than

four times the size of hindbody. Anterior end

without accessory suckers or other adhesive

structures. Posterior end without copulatory bursa.

Vitelline follicles small, lateral, posterior to

tribocitic organ, anterior to ovary. Uterus short,

intercaecal, posterior to tribocitic organ.

Paraprostate short. Uterus, Ejaculatory duct and

Paraprostate opening separately into small genital

atrium. Neotropical. Type and only species P.

synbranchi.

Species Parvaprostatum synbranchi n. sp.

Description based in 5 specimens (holotype and

paratypes) unless indicated otherwise.

Measurements expressed in micrometers (µm)

unless indicated otherwise, under the form Average

(Minimum-Maximum) and Length x Width, when

corresponding.

Body type holostome, elongate, bipartite without

notable constriction (Figure 1); total large, 11.49

mm (9.88-13.63), maximum width/total large

ratio, 1:0.14 (0.11-0.17); forebody flattened,

slightly convex ventrally 3.09 mm (3-3.40) x 1.6

mm (1.38-1.86), hindbody cylindrical with round

Neotropical Helminthology, 2019, 13(2), jul-dic Parvaprostatum synbranchi n. gen. n. sp.

154

end, 8.4 mm (6.86-11.78); forebody/hindbody

ratio, 1:2.35 (1.93-2.67). Paranephridial plexus

present in fresh specimens, following

'Diplostomulum' pattern; protonephridia not

visible. Anterior end without accessory suckers or

other adhesive structures. Oral sucker terminal or

subterminal, small, circular 131 (120-150).

Prepharynx not noticeable; pharynx small,

spherical, bulbous biradiated, 73 (60-80);

esophagus very short, 237 (130-285); intestinal

ceca bifurcation anterior to acetabulum, ceca

ending near posterior end, 10.31 mm (9.30-12.50)

x 145 (122-150), ceca length/total length ratio,

1:0.9 (0.74-0.97). Ceca with food content.

Acetabulum vestigial, circular or oval, 95 (70-135)

x 80 (70-100), ventrally medial, between ceca

bifurcation and tribocitic organ. Tribocitic organ

oval longitudinally, pre-equatorial, 572 (480-660)

x 338 (300-370), distance to anterior end, 1.97 mm

(1.63-2.40). Papilla in the medial line of tribocitic

organ and proteolytic glands not visible.

Figure 1. Parvaprostatum synbranchi n. gen. n sp. In toto photograph (left) with corresponding descriptive linear schematization

(right). Note the uterus not visibly reflecting antero-posteriorly due to superposition of the structure.

Neotropical Helminthology, 2019, 13(2), jul-dic Vettorazzi Fernandez et al.

Vitelline follicles small, lateral, coinciding with

intestinal ceca, posterior to tribocitic organ,

anterior to ovary. Ovary in posterior zone of

hindbody, spherical or ovoid, pretesticular, in

contact with anterior testis, 120 (100-145) x 122

(90-145). Oviduct emerges posteriorly to ovary

sinuously connecting to intertesticular Mehlis'

gland, associated to Ootype. Laurer's canal

emerges obliquely from oviduct near ovary (Figure

2) opening into gonopore. Vitelline reservoir

triangular or irregular, intertesticular, 150 (120-

170) x 174 (150-210), with two efferent vitelline

ducts and one deferent ootype duct. Ootype

intertesticular, anterior to vitelline reservoir, 168

(133-200) x 58 (38-75) (n=4). Uterus short,

intercaecal, projecting anteriorly to posterior end

of tribocitic organ, then descending into genital

atrium; holding 60 (43-76) eggs. Testis subequal, in

tandem, spherical or ovoid, posterior to ovary,

anterior testis 167 (125-210) x 161 (115-190),

posterior testis 170 (135-230) x 183 (160-220).

Efferent ducts of testis conjoin forming a single

duct directed posteriorly which widens forming

sinuous seminal vesicle, 376 (270-480) x 22 (20-

28); seminal vesicle thins posteriorly, becoming

spermiduct (Figure 2) which opens to genital

atrium. Paraprostate small, 148 (120-180) x 36 (30-

50), opening separately from spermiduct and

oviduct, into genital atrium. Excretory pore in

posterior end, terminal or subterminal.

Eggs measured in vivo, 120 (110-130) x 62 (60-70)

(n=10).

Figure 2. Detail of the genitalia of Parvaprostatum synbranchi. Reconstruction based on the study of all specimens. Note small

paraprostate opening separately from spermiduct and uterus into small genital atrium. References: AT) Anterior Testis; LD)

Lourer's Canal; MG) Mehlis' Gland; OD) Oviduct; Ov) Ovary; PPt) Paraprostate; PT) Posterior Testis; SD) Spermiduct; SV)

Seminal Vesicle; Vit) Vitellaria; VR) Vitellaria Reservoir.

Neotropical Helminthology, 2019, 13(2), jul-dic Parvaprostatum synbranchi n. gen. n. sp.

155

Taxonomic summary

Type host: Synbranchus marmoratus Bloch, 1795

Type locality: Sauce Lagoon, Maldonado,

Uruguay.

Site of Infection: body cavity under mesenteries,

liver, gonads.

Prevalence (CI): 60 (15-95) %

Mean Intensity (BCa): 26 (5-45)

Type species: Parvaprostatum synbranchi

Commentary

New genus name Parvaprostatum, comes from

Latin parva- small, prostatum- prostate, in

reference to the small size of the paraprostate.

Specific epithet synbranchi comes from the host

genus, Synbranchus.

Table 1. Biometric comparison of the descriptions of Massoprostatum Caballero, 1948 previously reported versus

Parvaprostatum synbranchi. All measurements expressed in micrometers (µm) in the format Average (Minimum

Value-Maximum Value) when the data was available. Data from present work taken from 5 individuals except Egg

size which was taken from 10 fresh individuals. Reference: AT) Anterior Testis; FB) Forebody; HB) Hindbody; OS)

Oral Sucker; Ov) Ovary; PT) Posterior Testis; SV) Seminal Vesicle; TL) Total Length; TO) Tribocitic Organ; VR)

Vitellaria Reservoir; VS) Ventral Sucker (Acetabula).

M. longum (Caballero,

1947)

M. longum

(Alvarez et

al., 2005)

Parvaprostatum synbranchi

(present work)

10500 (10072-10544)

1730 (1400-2060)

11489 (9875-13650)

Forebody

873-1183 x 336-673

280

3090 (3000-3400) x 1610 (1375-

1875)

Hindbody

9454-9635 x 673-763

1600

8400 (6875-11775) x

1250

HB/FB

8.15-10.8

5.71

2.35 (1.93-2.67)

46-50 x 58

44 (39-49)

131 (120-150)

Pharynx

46-54 x 25-37

35 (31-39)

73 (60-80) x 77 (70-85)

Esophagus

104-121

200

237 (130-285)

71 x 112-116

39 (23-55)

95 (70-135) x 80 (70-100)

283-291

x 250-270

100

572 (480-660) x 381 (370-400)

Ceca

Width 12-21; Smooth,

extends up to posterior end

Smooth; extends up to

posterior end

Width 145 (122-15); Smooth,

extends up to posterior end

Ovary

162-175 x 216-229

97 (85-109) x 111 (103-

109)

120 (100-145) x 121 (90-145)

354-364 x 381-382

170 (140-180) x 220

(200-250)

147 (100-210) x 161 (115-190)

364-366 x 361-382

180 (141-230) x 210

(180-250)

170 (140-230) x 183 (160-220)

Vitellaria

From posterior end of holdfast

to posterior end of body

From anterior end of

holdfast to posterior end

of body

From anterior end of holdfast not

reaching anterior end of ovary

50-180 x 156-225

150 (120-170) x 174 (150-210)

Uterus

Intercaecal; anterior to ovary

Intercaecal; anterior to

ovary

Intercaecal; anterior to ovary

Egg size

79-112 x 46-62

96 (87-110) x 69 (59-79)

120 (110-130) x 62 (60-70)

Paraprostate

1684-1839 x 42-46

148 (120-180) x 36 (30-50)

1539-2271 x 58-79

376 (270-480) x 22 (20-30)

Spermiduct

308-1040 x 12-21

472 (390-650) x 13 (12-15)

Neotropical Helminthology, 2019, 13(2), jul-dic Vettorazzi Fernandez et al.

156

DISCUSION

The family Proterodiplostomidae in South

America, has been reported for Argentina, Brazil,

Colombia, Paraguay, Venezuela and Uruguay,

summing a total of 11 genus and 18 species in the

continent (Mañé-Garzón & Holcman-Spector,

1969; Eiras et al., 2010; Das et al., 2011; Kohn &

Fernándes, 2014; Palumbo & Diaz, 2018). In

particular, the subfamily Massoprostatinae

Yamaguti, 1958, possesses only one genus,

Massoprostatum Caballero, 1948, and one species,

Massoprostatum longum Caballero, 1948, which is

defined by characteristics of the subfamily,

notably: body bipartite; forebody small, spoon-

shaped; hindbody cylindrical, very long;

pseudosuckers absent; oral and ventral suckers

small; holdfast organ small, round, with papillate

margins of aperture; pharynx small; oesophagus

short; caeca reaching close to posterior end of

body; testes tandem but slightly diagonal, near

posterior extremity; ovary pretesticular;

vitellarium extends full length of hindbody;

paraprostate long, sinuous, opening beside

ejaculatory duct at tip of small genital cone; uterus

opens separately; copulatory bursa small, with

terminal aperture. Host type and distribution are

also considered diagnostic characters, which are

crocodilians hosts and Neotropical distribution

(Gibson et al., 2002). According to the species

checklist of Tellez (2014), M. longum has been

found in Crocodylus morelatii Duméril & Bibron,

1851 (Caballero, 1947) in Mexico and Caiman

crocodylus fuscus Cope, 1868 (Alvarez et al.,

2005) in Colombia, which circumscribes the

distribution of the species, and by transitive, of the

subfamily, strictly to southern Central America and

northern South America. Consequently, the

taxonomic key of Niewiadomska (Key to

Trematoda, Gibson et al., 2002), places the

specimens herby found under the subfamily

Massoprostatinae due to the disposition of the

gonads and the defining character of vitellaria not

reaching the forebody. Furthermore, general

characteristics already mentioned, such as body

bipartite, forebody more than two times smaller

than hindbody, lack of pseudo-suckers, esophagus,

pharynx, acetabulum and tribocitic organ small,

ceca very long reaching up to posterior end of body

and uterus and spermiduct opening into the same

genital atrium with a common excretory pore, all

strengthen this classification.

Comparing the two published descriptions of M.

longum (Table 1) with the specimens, the latter

present important morphological and biometrical

distinctions: larger body size, no notable

differences between width of forebody and

hindbody, notably smaller hindbody/forebody

ratio; differences in size and form to tribocitic

organ; vitellaria posterior to tribocitic organ and

anterior to ovary; testis and ovary similar in size,

testis small in relation to total length; notably

smaller seminal vesicle; paraprostate very small.

The contrasting size of the paraprostate is of utmost

relevancy given it is a key trait in the classification

of the family, subfamily, genus and species.

Additionally, distribution area and host are novel

for M a s s o p r o s t a t i n a e as a whole. The

dissimilarities with the subfamily lead us to believe

that, perhaps, certain features which define this

hierarchy are more related to the species level. We

propose the following description for the

subfamily Massoprostatinae to fit the inclusion of

the new genus, modified from Key to Trematoda

Vol. 1 (Gibson et al., 2002):

Body bipartite; forebody small, spoon-shaped;

hindbody cylindrical, more than two times longer

than forebody. Pseudosuckers absent; oral and

ventral suckers small; holdfast organ small, round

or oval, with or without papillate margins of

aperture. Pharynx small; oesophagus short; caeca

reaching close to posterior end of body. Testes

tandem, slightly diagonal, near posterior extremity.

Ovary pretesticular. Vitellarium confined to

hindbody. Paraprostate present, opening beside

ejaculatory duct at tip of small genital cone.

Copulatory bursa small with terminal aperture, or

absent. In crocodilians and eels. Neotropical. Type

genus Massoprostatum Caballero, 1948.

The key to genera should then depend mainly on

the size of the paraprostate, with some supporting

characters to reinforce the classification:

Paraprostate large; forebody length more than four

times the size of hindbody; vitellaria reaching

posterior end of body……………….………..

Massoprostatum, Caballero 1948

Paraprostate small; forebody length less than four

times the size of hindbody; vitellaria not surpassing

Neotropical Helminthology, 2019, 13(2), jul-dic Parvaprostatum synbranchi n. gen. n. sp.

157

parasitizing a piscivore avian (Egreta garzetta

Linnaeus, 1766) (Dharejo et al., 2011).

Future works should focus on completing the

lifecycle of this new species, to better understand

the oddity of its type host and locality, as well as

include comparative genetic data to shed more light

into the subjacent evolutionary trends.

We thank Adriana Hernandez, Diego Nuñez and

Walter Norbis for provioling the hosts. We also

thank Gerardo Viera for helping with the

preparation of chemical solutions, and the

anonymous referee for their input.

anterior end of ovary...………..……....

Parvaprostatum, present work.

The lack of reports makes it difficult to conclude if

Massoprostatinae is specific to crocodilians and

thus, we cannot ascertain if our report in eels imply

either host-switching or life cycle shortening. If the

latter case is true, the specimens should then be

progenetic metacercaria (metacercarial

development of somatic and sexual characteristics

like those of an adult while in an intermediary host,

shortening the lifecycle (Poulin & Cribb, 2002;

Lefebvre & Poulin, 2005). The family

Proterodiplostomidae has reports of progenetic

metacercaria (Crocodilicola pseudostoma

(Willemoes-Suhm, 1870) Poche, 1925, in body

cavity of Rhamdia guatemalensis (Günther, 1864)

(Pérez-Ponce de León et al., 1992); C.

pseudostoma in body cavity of Hemisorubim

platyrhynchos Cuvier & Valenciennes, 1840

(Guidelli et al., 2003), therefore making it probable

that the proposed species Parvaprostatum

synbranchi is progenetic as well. While it could be

controversial to use them as basis for the report of a

new species, the conspicuous development of

structures such as the tribocitic and reproductive

organs, the finding of food content in the ceca, and

the fact that they were found un-encysted and

gravid, lead us to consider the specimens adequate

and morphologically reliable. This same

argumentation has already been applied by other

authors (Ibañez & Jara, 1999; Arredondo, 2013)

that describe new species based on metacercaria. It

is worth mentioning that although they are referred

to as progenetic metacercaria, this is only to

emphasize their sexual development in a secondary

intermediate host, but they are not neotenic

(Lefebvre & Poulin, 2005).

In Uruguay, the only known crocodilian species is

Caiman latirostris Daudin, 1801, distributed in the

west (Rio Uruguay basin) and east (Merin Lagoon

basin) of the country, with no reports in coastal

lagoons such as Sauce Lagoon (Borteiro et al.,

2006). It becomes difficult to theorize a scenery of

host-switching with the current state of knowledge.

Another explanation would be that the assumed

host specificity might be a consequential bias

resulting from the scarcity of studies regarding this

parasitic family, as hinted by the description of a

proterodiplostomid species (Paradiplostomum

spatulatum Dharejo, Bilqees & Khan, 2011)

ACKNOWLEDGMENTS

Acosta, AA, Caffara, M, Fioravanti, ML,

Utsunomia, R, Zago, AC, Franceschini, L &

Silva, RJD. 2016. Morphological and

m o l e c u l a r c h a r a c t e r i z a t i o n o f

Clinostomum detruncatum (Trematoda:

Clinostomidae) metacercariae infecting

Synbranchus marmoratus. The Journal of

Parasitology, vol. 102, pp. 151-157.

Alvarez, A, Lenis, C & Velez, I. 2005. First report

of two species of trematodes (Digenea:

Proterodiplostomidae) for Colombia in

Caiman crocodylus fuscus (Reptilia:

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