Demidospermus annulus sp. nov. (Platyhelminthes, Monogenea, Ancyrocephalidae) is described from the gills of the catfish Parapimelodus valenciennis Lütken collected in Samborombón Bay, Argentina. The new species differs from all congeneric species mainly by the structure of the accessory piece of the male copulatory organ, the sclerotized ring-shaped vaginal aperture and the dorsal bar articulation.Centro de Estudios Parasitológicos y de Vectore

Marcotegui, Paula Soledad

Martorelli, Sergio Roberto

Acta Parasitologica

English

SEDICI - Repositorio de la UNLP

DOI: 10.2478/s11686-011-0030-1
© W. Stefan´ski Institute of Parasitology, PAS
Acta Parasitologica, 2011, 56(2), 116–121;  ISSN 1230-2821
A new species of Demidospermus 
(Platyhelminthes, Monogenea, Ancyrocephalidae) 
from the catfish Parapimelodus valenciennis
in Samborombón Bay, Argentina
Marcotegui Paula S.* and Martorelli Sergio R.
CEPAVE (CCT – CONICET – LA PLATA) (FCNyM-UNLP), 2 No. 584, La Plata, Buenos Aires, CP 1900, Argentina
Abstract
Demidospermus annulus sp. nov. (Platyhelminthes, Monogenea, Ancyrocephalidae) is described from the gills of the catfish
Parapimelodus valenciennis Lütken collected in Samborombón Bay, Argentina. The new species differs from all congeneric
species mainly by the structure of the accessory piece of the male copulatory organ, the sclerotized ring-shaped vaginal aper-
ture and the dorsal bar articulation. 
Keywords
Monogenea, Demidospermus, catfish, Salado River, western Atlantic coast
Introduction
Currently, there are 20 nominal species of Demidospermus
(Platyhelminthes, Monogenea, Ancyrocephalidae) parasitiz-
ing siluriform fishes from South America (Kritsky and Gutiér-
rez 1998, França et al. 2003, Cohen and Kohn 2008, Men-
doza-Franco and Scholz 2009, Cepeda and Luque 2010, Mon-
teiro et al. 2010). The major numbers of species were reported
from Brazilian waters, a total of 11 species found in 7 hosts
species. In Argentina 10 species have been reported in Río de
La Plata, Río Uruguay, and Río Salado (Santa Fe) from six
fishes species of families Pimelodidae, Heptapteridae, Lori-
cariidae and Auchenipteridae.
Samborombón Bay is located in the south-western region
of the Río de La Plata estuary, between Punta Piedras
(32°57΄S, 57°08΄W) and Punta Rasa (36°18΄S, 56°48΄W), on
the northeast coast of Buenos Aires Province. This area en-
compasses Argentina’s most extensive mixohaline wetland.
During a study of parasites of Parapimelodus valenciennis
from this area, a new species of Demidospermus Suriano,
1983 was collected. In this paper the new species is described
and illustrated.
Materials and methods
Specimens of P. valenciennis were collected using cast nets
between 2006 and 2008 from the Salado River, the main river
entering Samborombón Bay. Live fish were transported to the
laboratory in containers filled with estuarine water and held in
oxygenated aquaria prior to their examination. A total of 118
fish, ranging in total length from 5.9 to 22.3 cm, were exam-
ined for parasites. Excised gills from freshly killed fishes were
examined under a dissecting microscope, and monogeneans
were collected, heat-fixed without pressure, preserved in 10%
formalin and mounted in glycerine-jelly for study. In order to
study details of their internal anatomy, 25 specimens of mono-
geneans were heat-fixed under pressure, preserved in 10% for-
malin, then stained with Van Cleave’s haematoxylin, passed
through a series of increasing ethanol concentrations between
70 and 100%, cleared in clove oil and mounted in Canada bal-
sam. Other specimens were stained using Gomori’s stain for
studying the sclerotized hard-parts.
Measurements and drawings were made using a Nikon
Optiphot-2 microscope with DIC optics at magnifications of
×400 and ×1,000 and a Wild M20 microscope at a magnifica-
*Corresponding author: pmarcotegui@fcnym.unlp.edu.ar
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Demidospermus annulus sp. nov. from the catfish 117
tion of ×1,500 for the sclerotized hard-parts and internal or-
gans. Figures were prepared with the aid of a drawing appa-
ratus. Microphotographs of the sclerotized structures were
taken using DIC optics on an Olympus BX51 microscope with
an Olympus digital camera. The measuring scheme of anchors
and bar is presented in Figure 1. Measurements are given in
micrometres as the mean with the range in parentheses. Num-
bering (distribution) of hooklets pairs following Mizelle
(1963) for adult dactylogyrids. 
The following abbreviations are used throughout the text:
APL, accessory piece length; BL, body  length; BW, body
width; DABW, dorsal anchor base width; DAL, dorsal anchor
Fig. 1. Scheme of measurements for the anchors and bars: a – bar length, b – bar distance between ends, c – anchor length, d – anchor base
width
Fig 2. Demidospermus annulus sp. nov.: a – entire worm, ventral view; b – sclerotized vagina; c – dorsal bar; d – dorsal anchor; e – ventral
bar; f – ventral anchor; g – hook pair I; h – hook pair VII; i – hook pairs II–VI; j – male copulatory organ, tube and accessory piece. Scale
bars = 20 µm (a, c-f), 25 µm (b, g-i), 20 µm (j)
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Paula S. Marcotegui and Sergio Martorelli 118
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Unauthenticated
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Demidospermus annulus sp. nov. from the catfish 119
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Paula S. Marcotegui and Sergio Martorelli 120
length; DBDBE, dorsal bar distance between ends; DBL, dor-
sal bar length; DP, diameter of pharynx; GL, germarium
length; GW, germarium width; MCO, male copulatory organ;
MCOL, MCO length; VABW ventral anchor base width; VAL,
ventral anchor length; VBDBE, ventral bar distance between
ends; VBL, ventral bar length; TL, testes length; TW, testes
width.
Demidospermus annulus sp. nov. (Fig. 2, Table I)
Description. Body 620 (392–936) long, fusiform, maximum
width 156 (90–240) at level of gonads. Two terminal, and 2 bi-
lateral, cephalic lobes. Four eye-spots. Pharynx subspherical,
41 (26–50) in diameter. Testes ovoid, 168 (151–184) long, 81
(50–112) width. MCO J-shaped, 70 (63–80) long. Accessory
piece 30 (27–36) long, straight to slightly curved, rod-shaped,
only distal end in contact with MCO. Vas deferens looping left
intestinal caecum. Vaginal aperture sinistral, sclerotized ring-
shaped, leading to seminal receptacle. Germarium ovoid, 117
(85–150) long, 56 (37–86) wide. Vitellaria scattered through-
out trunk. Similar anchors, short shaft, elongated point, roots
poorly defined. Ventral anchor 28 (21–32) long, base 15 (10–
18). Dorsal anchor 26 (21–29) long, base 15 (10–28). Ventral
bar slightly V- or U-shaped 59 (46–67) long, distance between
ends 54 (47–58). Dorsal bar V-shaped with articulation, 47
(42–52) long, distance between ends 43 (37–48). Hooks dis-
similar in size, each with recurved point, pair I 22 (21–24)
long, pairs II, III, IV, V 18 (17–22) long, pair VI 13 (12–15)
long, pair VII 11 (10–12) long. 
Type host: Parapimelodus valenciennis (Lütken, 1874). 
Site of infection: Gill lamellae.
Type locality: Samborombón Bay (32°57΄S, 57°08΄W),
Buenos Aires, Argentina.
Specimens deposited: Deposited in the Museo de la Plata,
Invertebrates Collection. La Plata, Argentina. Holotype No.
MLP 6302, paratypes No. MLP 6303.
Etymology: The specific name is from Latin (annulus =
ring) and refers to the ring-shaped sclerotized vaginal aper-
ture.
Remarks
The features of specimens analyzed here agree with the genus
Demidospermus Suriano, 1983 and the emended diagnosis
provided by Kritsky and Gutiérrez (1998). Demidospermus
species can be readily distinguished from other species of the
genus by the morphology of the MCO, the ring shaped vagi-
nal sclerite, and measurements of the sclerotized parts of the
haptor.
Demidospermus valenciennesi Gutiérrez et Suriano, 1992
has been previously reported on Parapimelodus valenciennis
from Río de La Plata, Buenos Aires, Argentina. The new
species can be distinguished from D. valenciennesi by the
greater distance between the ends of the dorsal bar and distal
ends of the ventral bar, and by the bigger measurement of:
hooks (I and II), testes, germarium, MCO, and accessory piece
of MCO (see Table). Additionally, the MCO accessory piece
of D. valenciennesi is sheath-like instead of rod-shaped in the
new species, the dorsal bar has an articulation in the new
species, and by the morphology of vaginal sclerite that is
clearly different in the new species compared with D. valen-
ciennesi.
Currently, nine species of Demidospermus have been re-
ported from the Río de La Plata, D. anus Suriano, 1983 from
Loricariichthys anus, D. paravalenciennesi Gutiérrez et Suria-
no, 1992, D. bidiverticulatum Suriano et Incorvaia, 1995, and
D. armostus Kritsky et Gutiérrez, 1998 from Pimelodus macu-
latus, D. cornicinus Kritsky et Gutiérrez, 1998 and D. lep-
tosynophallus Kritsky et Gutiérrez, 1998 from Bergiaria 
westermanii, D. idolus Kritsky et Gutiérrez, 1998 and D. ma-
jusculus Kritsky et Gutiérrez, 1998 from P. albicans, and
D. uncusvalidus Gutiérrez et Suriano, 1992 from P. maculatus
and Trachelyopterus galeatus. The new species differs from all
these species by the morphology of the MCO, by the meas-
urements of haptoral pieces, and by the size of the testes and
germarium (Table I). 
Conversely, D. annulus sp. nov. resembles D. cecarrelli
Cepeda et Luque, 2010 by the J-shaped MCO. However, the
new species can be distinguished from D. ceccarelli by the
morphology of accessory piece of MCO. 
In summary, D. annulus sp. nov. differs from all con-
generic species by the structure of the MCO accessory piece,
the sclerotized ring-shaped vaginal aperture and the dorsal bar
articulation. 
Acknowledgements. This work was funded by a fellowship grant
from Consejo Nacional de Investigaciones Científicas y Tecnológi-
cas (CONICET) and UNLP to the authors.
References
Cepeda P., Luque J. 2010. Three new species of Demidospermus
(Monogenea: Dactylogyridae) parasitic on Brachyplatystoma
filamentosum (Siluriformes: Pimelodidae) from the Araguaia
River, Brazil. Journal of Parasitology, 96, 869–873. DOI:
10.1645/GE-2331.1.
Chemes B., Takemoto R., Sottini R. 2008. Comunidad de Monoge-
nea en las branquias de Pimelodus albicans (Valenciennes,
1840) en el río Salado del Norte, San Justo (Santa Fe, Argen-
tina). Parasitologia Latinoamericana, 63, 51–57.
Cohen S.C., Kohn A. 2008. South American Monogenea – list of
species, hosts and geographical distribution from 1997 to
2008. Zootaxa, 1924, 1–42.
França J.G., Isaac A., Pavanelli G.C., Takemoto R.M. 2003. Dacty-
logyridae (Monogenea) from the gills of Iheringicthys labro-
sus (Osteichthyes: Pimelodidae) from the upper Paraná river
floodplain, Brazil, with the proposal of Pseudovancleaveus
n.g. Systematic Parasitology, 54, 25–31. DOI: 10.1023/A:1022
113626634.   
Gutiérrez P.A., Suriano D.M. 1992. Ancyrocephalids of the genus
Demidospermus Suriano, 1983 (Monogenea) parasites from
siluriform fishes in Argentina, with descriptions of three new
species. Acta Parasitologica, 37, 169–172.
Unauthenticated
Download Date | 10/9/19 10:15 PM
Demidospermus annulus sp. nov. from the catfish 121
Kritsky D.C., Gutiérrez P.A. 1998. Neotropical Monogenoidea. 34.
Species of Demidospermus (Dactylogyridae, Ancyrocephali-
nae) from the gills of pimelodids (Teleostei, Siluriformes) in
Argentina. Journal of the Helminthological Society of Wash-
ington, 65, 147–159.
Mendoza-Franco E., Scholz T. 2009. New dactylogyrids (Monoge-
nea) parasitizing the gills of catfishes (Siluriformes) from the
Amazon River Basin in Peru. Journal of Parasitology, 95,
865–870. DOI: 10.1645/GE-1820.1.
Mizelle J. 1963. New species of trematodes from gills of Illinois
fishes. American Midland Naturalist, 17, 785–1029.
Monteiro C., Kritsky D., Brasil-Sato M. 2010. Neotropical Mono-
genoidea. 55. Dactylogyrids parasitising the pintado-amarelo
(Accepted February 16, 2011)
Pimelodus maculatus Lacépède (Actinopterygii: Pimelodi-
dae) from the Rio Sao Francisco, Brazil. Systematic Parasit-
ology, 76, 179–190. DOI: 10.1007/s11230-010-9250-2.
Suriano D.M. 1983. Demidospermus anus gen. nov. sp. nov. (Mono-
genea: Ancyrocephalinae) parasito branquial de Loricaria
anus Valenciennes, 1840 (Pisces: Loricariidae) de la laguna
de Chascomus, provincia de Buenos Aires, Republica Argen-
tina. Neotropica, 29, 111–119.
Suriano D.M., Incorvaia I.S. 1995. Ancyrocephalid (Monogenea)
parasites from siluriform fishes from the Paranean-Platean
ichthyogeographical province in Argentina. Acta Parasito-
logica, 40, 113–124.
Unauthenticated
Download Date | 10/9/19 10:15 PM


A new species of Demidospermus (Platyhelminthes, Monogenea, Ancyrocephalidae) from the catfish Parapimelodus valenciennis in Samborombón Bay, Argentina

http://sedici.unlp.edu.ar/bitstream/handle/10915/83979/Documento_completo.pdf?sequence=1

A new species of Demidospermus (Platyhelminthes, Monogenea, Ancyrocephalidae) from the catfish Parapimelodus valenciennis in Samborombón Bay, Argentina

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