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Dactylogyrids (Platyhelminthes, Monogenea) from the gill
lamellae of doradids (Siluriformes) with description of five new
species of Cosmetocleithrum and new geographical distribution
for known species from the Neotropical Region, Brazil
Augusto Leandro de Sousa Silva
1
, Yuri Costa de Meneses
2
, Williane Maria de Oliveira Martins
3
,
Simone Chinicz Cohen
2,*
, Andréa Pereira da Costa
4
, and Marcia Cristina Nascimento Justo
2
1
Programa de Pós-graduação em Ciência Animal, Laboratório de Multiusuários em Pesquisa da Pós-graduação (LAMP) –
Universidade Estadual do Maranhão (UEMA). Cidade Universitária Paulo VI, Avenida Lourenço Vieira da Silva, 1000,
São Luís, Maranhão, MA, Brazil
2
Laboratório de Helmintos Parasitos de Peixes, Instituto Oswaldo Cruz, FIOCRUZ, Av. Brasil, 4365, Rio de Janeiro,
RJ 21045-900, Brazil
3
Laboratório de Biologia Geral do Instituto Federal de Acre (IFAC), Campus Cruzeiro do Sul, Estrada da Apadec no. 1192,
Bairro Nova Olinda, CEP: 69980-000, Cruzeiro do Sul, Acre, Brazil
4
Laboratorio de Parasitologia e Doenças Parasitárias dos Animais –LPDP, UEMA, Cidade Universitária Paulo VI,
Avenida Lourenço Vieira da Silva, 1000, São Luís, Maranhão, MA, Brazil
Received 10 October 2023, Accepted 12 November 2023, Published online 8 December 2023
Abstract – Five new species of Cosmetocleithrum were described parasitizing the gill filaments of neotropical doradid
fishes. Cosmetocleithrum undulatum n. sp., Cosmetocleithrum brachylecis n. sp. and Cosmetocleithrum ludovicense
n. sp. are described from Platydoras brachylecis from a market-place of São Luís, State of Maranhão, Brazil.
Cosmetocleithrum sacciforme n. sp. and Cosmetocleithrum basicomplexum n. sp. are described from Oxydoras niger
from Juruá River, State of Acre, Brazil. Cosmetocleithrum undulatum and Cosmetocleithrum brachylecis resemble
Cosmetocleithrum falsunilatum Feronato, Razzolini, Morey & Boeger, 2022 mainly by the unique male copulatory
organ (MCO) morphology but differ from these and all congeneric species mainly by the morphology of the MCO,
accessory piece and hooks pairs. Cosmetocleithrum ludovicense is closer to Cosmetocleithrum confusus Kritsky,
Thatcher & Boeger, 1986 and to Cosmetocleithrum akuanduba Soares, Santos Neto & Domingues, 2018 but
differs from those mainly by the morphology of the accessory piece. Cosmetocleithrum sacciforme differs from all
congeneric species mainly by the morphology of the accessory piece formed by a single plate of saccular appearance.
Cosmetocleithrum basicomplexum also shares morphological characters with Cosmetocleithrum gigas Morey,
Cachique & Babilonia, 2019 considering the size of the body and shape of the anchors, but differs mainly in the
morphology of the bars and hooks. Besides the new species, new data are presented for Cosmetocleithrum leandroi
Soares, Neto & Domingues, 2018, C. akuanduba and C. confusus regarding morphological characteristics and
biogeography.
Key words: Cosmetocleithrum, Dactylogyridae, Monogeneans, Doradidae, South America.
Re
´sume
´–Dactylogyridae (Platyhelminthes, Monogenea) des lamelles branchiales de Doradidae (Siluriformes)
avec description de cinq nouvelles espèces de Cosmetocleithrum et nouvelle répartition géographique d’espèces
connues de la région néotropicale au Brésil. Cinq nouvelles espèces de Cosmetocleithrum sont décrites, parasitant les
filaments branchiaux de poissons Doradidae néotropicaux. Cosmetocleithrum undulatum n. sp., Cosmetocleithrum
brachylecis n. sp. et Cosmetocleithrum ludovicense n. sp. sont décrits de Platydoras brachylecis provenant d’un
marché de São Luís, État du Maranhão, Brésil. Cosmetocleithrum sacciforme n. sp. et Cosmetocleithrum
basicomplexum n. sp. sont décrits d’Oxydoras niger de la rivière Juruá, État d’Acre, Brésil. Cosmetocleithrum
undulatum et Cosmetocleithrum brachylecis ressemblent à Cosmetocleithrum falsunilatum Feronato, Razzolini,
Morey & Boeger, 2022 principalement par la morphologie unique de l’organe copulateur mâle (OCM), mais
diffèrent de ces espèces et de toutes les espèces congénères principalement par la morphologie de l’OCM, de la
Edited by Jean-Lou Justine
*Corresponding author: scohen@ioc.fiocruz.br;cohen.simone@gmail.com
Parasite 30, 53 (2023)
ÓA.L. Silva et al., published by EDP Sciences, 2023
https://doi.org/10.1051/parasite/2023054 Available online at:
urn:lsid:zoobank.org:pub:ABB00F93-232A-4551-930D-DBEFDCE602C8 www.parasite-journal.org
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0),
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
OPEN ACCESS
R
ESEARCH
A
RTICLE
pièce accessoire et des paires de crochets. Cosmetocleithrum ludovicense est proche de Cosmetocleithrum confusus
Kritsky, Thatcher & Boeger, 1986 et de Cosmetocleithrum akuanduba Soares, Santos Neto & Domingues, 2018
mais en diffère principalement par la morphologie de la pièce accessoire. Cosmetocleithrum sacciforme se distingue
de toutes les espèces congénères principalement par la morphologie de la pièce accessoire formée d’une seule
plaque d’aspect sacculaire. Cosmetocleithrum basicomplexum partage également des caractères morphologiques
avec Cosmetocleithrum gigas Morey, Cachique & Babilonia, 2019 compte tenu de la taille du corps et de la forme
des anchors, mais en diffère principalement par la morphologie des barres et des crochets. Outre les nouvelles
espèces, de nouvelles données sont présentées pour Cosmetocleithrum leandroi Soares, Neto & Domingues, 2018,
C. akuanduba et C. confusus concernant les caractéristiques morphologiques et la biogéographie.
Introduction
The neotropics, spanning from central Mexico to the south-
ern limit of South America, has the most diverse group of fishes
on the planet [14]. This region harbors the greatest diversity of
freshwater fish with approximately 6,000 known species and
estimates of 9,000 species [18]. Of the total known species,
the Characiformes, Siluriformes, and Gymnotiformes account
for approximately 77% of the known species [2]. Thus, South
America harbors the most diverse fauna of continental freshwa-
ter fish in the world with approximately 5,750 known species
[3]. Siluriformes, collectively known as catfish, stand out as
the largest and most diverse order of freshwater fish, and con-
stitute one of the most important components of the Neotropical
fauna, with more than 3,800 described species [6]. Among all
the families of this order, Doradidae stand out as one of the
most diverse and representative families among the Neotropical
Siluriformes, with more than 90 valid species [6]. Doradidae are
a monophyletic group endemic to freshwaters of South America
on both sides of the Andes Mountains [19].
Siluriformes host a remarkably rich and diverse fauna of gill
monogeneans, and these host-parasite systems are an attractive
model for phylogenetic studies in the Neotropics [4,12]. The
dactylogyrid Cosmetocleithrum Kritsky, Thatcher & Boeger,
1986 is one of the most species-rich groups of monogenoids
reported from siluriform fishes and was proposed to accommo-
date species of Dactylogyridae that parasitize Oxydoras niger
(Valenciennes) and Pterodoras granulosus (Valenciennes) in
the Amazon River basin [9]. This genus shows high specificity
to catfishes within Doradidae and Auchenipteridae [11]. Cur-
rently, 23 species of Cosmetocleithrum are recognized as para-
sites of the gills of neotropical Siluriformes, among which 15
species recorded in doradids hosts, eight in Auchenipteridae,
one parasitizing Pimelodidae, and one in Loricariidae. All spe-
cies of Cosmetocleithrum have been described from hosts of
members of a single family [1,4,5,15,22,23,24], except
for Cosmetocleithrum bulbocirrus Kritsky, Thatcher & Boeger,
1986, reported from species of three different siluriform fami-
lies and from Hoplias malabaricus (Bloch), a characiform fish
[7]. However, considering that only one specimen was found in
the latter host, this record needs to be confirmed.
During research on monogeneans of siluriform fishes
in northern and northeastern Brazil, five new species of
Cosmetocleithrum were found and are described herein. More-
over, new data are presented to Cosmetocleithrum leandroi
Soares, Neto & Domingues, 2018, Cosmetocleithrum
akuanduba Soares, Santos Neto & Domingues, 2018 and
Cosmetocleithrum confusus Kritsky, Thatcher & Boeger, 1986
regarding morphological characteristics and biogeographical
data, thus expanding the knowledge of these species.
Material and methods
The studies were carried out between 2019 and 2023 on
different doradid species collected from two distinct localities
in Brazil. Specimens of Oxydoras niger were captured with
gill nets and hook and line from Juruá River, Acre, Brazil
(7°40034.100S, 72°39039.500W) and those from Platydoras
brachylecis and Hassar affinis were obtained from street
markets located on the island of São Luís, State of Maranhão
(2°34018.000S44°11049.900W).
The gills of each specimen were removed and placed in
vials containing hot water (c. 65 °C) in order to relax the par-
asites, and they were then shaken to detach the parasites from
the gill filaments. Subsequently, absolute ethanol was added
to reach a concentration of 70%. The vials were then sent to
“Laboratório de Helmintos Parasitos de Peixes, Instituto
Oswaldo Cruz, FIOCRUZ”, where the gills were analyzed,
and the parasites identified. Monogeneans were picked using
a stereoscopic microscope for subsequent morphological stud-
ies. Some specimens were mounted in Hoyer’s medium for
study of the sclerotized parts; others were stained with
Gomori’s trichrome for study of the internal organs of the
parasite [8]. Measurements are presented in micrometers; range
values are followed by mean and number of structures mea-
sured in parentheses. Dimensions of organs and other structures
represent the greatest distance; lengths of curved or bent struc-
tures (anchors, bars, and accessory piece) represent the straight-
line distances between extreme ends [9], except for copulatory
complexes that were measured using ImageJ [17]. The speci-
mens were studied, photographed, and drawn using an
Olympus BX 41 microscope with phase contrast and Zeiss
Axioskop 2 Plus microscope with differential interference con-
trast (DIC), both equipped with a camera lucida. Holotypes,
paratypes, and vouchers of each species were deposited in the
“Coleção Helmintológica do Instituto Oswaldo Cruz -
CHIOC”, from “Fundação Oswaldo Cruz - FIOCRUZ”.
Results
Class Monogenea Bychowsky, 1937
Subclass Monopisthocotylea Odhner, 1912
Order Dactylogyridea Bychowsky, 1937
Dactylogyridae Bychowsky, 1933
Cosmetocleithrum Kritsky, Thatcher & Boeger, 1986
2Silva A.L.S. et al: Parasite 2023, 30,53
Cosmetocleithrum undulatum n. sp. (Fig. 1)
urn:lsid:zoobank.org:act:D915B062-6777-4D6F-8024-
C5CF6904F062.
Type-host: Platydoras brachylecis Piorski, Garavello, Arce
H & Sabaj Pérez, 2008 (Siluriformes, Doradidae).
Site in host: Gill lamellae.
Type-locality: Market-place of the Cidade Operária, São
Luís, State of Maranhão, Brazil (2°34018.000S44°11049.900W).
Parasitological indexes: Total number of hosts: 3; number
of infected hosts: 3; total number of parasites: 312.
Type-material: Holotype CHIOC 40257 a; Paratypes
CHIOC 40257 b–h; 40258 a–g.
Etymology: The specific name is derived from Latin
(undulatum = wavy) and refers to the shape of the male copu-
latory organ.
Description
Based on 21 specimens: 14 mounted in Hoyer’s medium
and 7 stained in Gomori’s trichrome. Body fusiform, elongated,
comprising cephalic region, trunk, peduncle, and haptor.
Figure 1. Cosmetocleithrum undulatum n. sp. from Platydoras brachylecis. (A) Total ventral view (composite); (B) Copulatory complex,
ventral view; (C) Hook pairs 1–4, 6, 7; (D) Hook pair 5; (E) Dorsal bar; (F) Ventral bar; (G) Ventral anchor; (H) Dorsal anchor. Scale bars: A,
100 lm, B, C, 10 lm, D, 50 lm, E, F, 15 lm, G, H, 20 lm.
Silva A.L.S. et al: Parasite 2023, 30,53 3
Tegument thin, smooth. Body, including haptor, 1069
(780–1380; n= 14) long by 228 (110–320; n=14)wideat
the level of germarium. Cephalic lobes poorly developed. Four
pairs of head organs. Cephalic glands indistinct. Eyes absent.
Accessory granules scattered in the pharyngeal region, some-
times gathered, resembling eyes. Mouth subterminal. Pharynx
spherical 52 (32–73; n= 7) in diameter. Esophagus short.
Two intestinal ceca confluent posteriorly to testis, lacking diver-
ticula. Gonads intercecal, tandem. Germarium 97 (83–125;
n=4)longby21(14–36; n= 4) wide. Vagina simple, non-
sclerotized; vaginal aperture sinistroventral. Seminal receptacle
pyriform. Mehlis’gland, uterus, oviduct, and ootype not
observed. Vitellaria extends throughout the trunk, except in
areas of other reproductive organs. Testis postgermarial,
49 (32–60; n=3)longby20(15–30; n= 3) wide. Vas deferens
looping left intestinal cecum; seminal vesicle a dilatation of vas
deferens. Prostatic reservoir elongated. Copulatory complex
comprising male copulatory organ (MCO) and accessory piece.
MCO formed by a wavy tube and sclerotized walls that
abruptly tapers at the tip; a thin, and delicate veil-shaped layer
covers the entire tip of the cirrus and involves the accessory
piece in its distal portion, 220 (200–249; n= 14) in total length.
Accessory piece straight, non-articulated to the base of the
MCO, 98 (86–116; n= 14) long. Peduncle conspicuous, long.
Haptor globose, with dorsal and ventral anchor/bar complexes,
177 (110–220; n= 14) wide. Ventral bar straight with enlarged
ends projecting posteriorly, 57 (49–72; n=14)wide.Dorsalbar
more straight with two submedian projections, 69 (57–85;
n= 14) wide. Ventral and dorsal anchors dissimilar in size
and shape. Ventral anchor with well-developed, square-shaped
superficial root and rounded deep root, curved shaft and point
not passing from the level of the tip of superficial root, outer
59 (55–61; n= 14); inner 50 (47–54; n=14);base33
(29–40; n= 14). Dorsal anchor with well-developed rectangular
superficial root and well-developed and rounded deep root,
evenly curved shaft and point not passing from the level of
the tip of superficial root, outer 41 (39–43; n= 14); inner 37
(35–43; n=14);base26(22
–30; n= 14). Hooks with ancyro-
cephaline distribution. Hooks dissimilar, pair 5 with a delicate
point, inconspicuous thumb, slender straight shank with point
slightly recurved, filamentous hook (FH) loop 3/4 shank length,
18 (17–19; n= 13); hook pairs 1–4, 6 and 7 with shaft
powerfully robust through its length, ending in a small rounded
portion at the end; thumb short, rounded; filamentous hook
(FH) loop about shank length, 16 (15–18; n= 78).
Remarks
Cosmetocleithrum undulatum n. sp. differs from all con-
generic species mainly in terms of the morphology of the
MCO, while resembling C. falsunilatum Feronato, Razzolini,
Morey & Boeger, 2022 with a unique MCO morphology, very
similar to the species of Unilatus Mizelle & Kritsky, 1967, that
are parasites of loracariids. However, Cosmetocleithrum undu-
latum n. sp. differs from C. falsunilatum regarding the shape of
the MCO, which in C. falsunilatum is rolled up into a cork-
screw shaped, while in Cosmetocleithrum undulatum n. sp.
the MCO is an undulating tube with a thin and delicate layer
that covers the entire tip of the MCO. Furthermore, the
accessory piece of C. falsunilatum is subdivided into two
regions that reach close to the base of the MCO, while in the
new species, the accessory piece is straight, reaching just less
than half of the length of the MCO. The hook pairs 1–4, 6, 7
of the new species are unique among the Cosmetocleithrum
species, with a shaft that is strongly robust throughout its
length, and with a small constricted portion ending with a small
rounded portion at the end.
Cosmetocleithrum brachylecis n. sp.
(Fig. 2)
urn:lsid:zoobank.org:act:57814DA6-2145-414F-9760-
A28D5036DAFD.
Type-host: Platydoras brachylecis Piorski, Garavello, Arce
H & Sabaj Pérez, 2008 (Siluriformes, Doradidae).
Site in host: Gill lamellae.
Type-locality: Market-place of the Cidade Operária, São
Luís, State of Maranhão, Brazil (2°34018.000S44°11049.900W).
Parasitological indexes: Total number of hosts: 3; number
of infected hosts: 3; total number of parasites: 38.
Type-material: Holotype CHIOC 40247 a; Paratypes
CHIOC 40247 b–m; 40248.
Etymology: The specific name is derived from the name of
its host, Platydoras brachylecis.
Description
Based on 16 specimens mounted in Hoyer’smediumand
3 stained in Gomori’s trichrome. Body fusiform, elongated,
comprising cephalic region, trunk, peduncle, and haptor. Body,
including haptor, 528 (360–660; n= 13) long by 116 (60–160;
n= 13) wide at the germarium level. Tegument thin, smooth.
Cephalic lobes poorly developed. Four pairs of head organs.
Cephalic glands indistinct. Eyes absent. Accessory granules
scattered in the cephalic and pharyngeal region. Mouth subter-
minal. Pharynx spherical, muscular 34 (27–43; n=9)indiam-
eter. Esophagus short. Two intestinal ceca confluent just
posteriorly to gonads, lacking diverticula. Gonads tandem,
germarium pre-testicular. Germarium 110 (72–157; n=4)long
by 23 (17–23; n= 4) wide. Vagina simple, non-sclerotized;
vaginal aperture sinistroventral. Seminal receptacle rounded.
Mehlis’gland, uterus, oviduct and ootype not observed.
Vitelline follicles dense, dispersed throughout trunk but absent
in region of reproductive organs and MCO. Testis posterior to
germarium 27 (22–32; n=4)longby27(22–35; n=4)wide.
Vas deferens looping left intestinal cecum; seminal vesicle a
dilatation of vas deferens. Prostatic reservoir anterior to seminal
vesicle. Copulatory complex comprising male copulatory organ
(MCO) and accessory piece. MCO composed as a spiral tube
with sclerotized walls, with counter-clockwise orientation,
68 (49–82; n= 13) in total length. Accessory piece straight,
elongated, exceeding the base of the cirrus, non-articulated to
the base, 45 (36–52; n= 13) long. Peduncle elongate. Haptor
globose, almost the same width as the body 104 (60–130;
n= 13) wide. Ventral bar slightly recurved with enlarged ends,
38 (24–43; n= 13) wide. Dorsal bar robust, broadly u-shaped,
with two submedian projections, 46 (25–55; n= 13) wide.
4Silva A.L.S. et al: Parasite 2023, 30,53
Figure 2. Cosmetocleithrum brachylecis n. sp. from Platydoras brachylecis. (A) Total, ventral view (composite); (B) Copulatory
complex, ventral view; (C) Hook; (D) Dorsal bar; (E) Ventral bar; (F) Ventral anchor; (G) Dorsal anchor. Scale bars: A, 100 lm, B, D–G,
20 lm, C, 10 lm.
Silva A.L.S. et al: Parasite 2023, 30,53 5
Ventral and dorsal anchors dissimilar in size and similar in
shape, robust superficial and deep roots; deep root straight;
superficial root pointed; evenly curved shaft, and short point.
Ventral anchor outer 37 (35–39; n= 13); inner 32 (27–43;
n=13);base23(19–26; n= 13). Dorsal anchor outer 29
(26–32; n= 13); inner 22 (18–25; n= 13); base 19 (16–20;
n= 13). Hooks with ancyrocephaline distribution. Hooks
similar in shape and size; point and shaft delicate, erect thumb,
shank expanded, tapering abruptly proximally in a point,
15 (13–16; n= 70); FH loop about 3/4 shank length.
Remarks
Cosmetocleithrum brachylecis n. sp. resembles C. falsunila-
tum and C. undulatum n. sp. regarding the shape of the MCO,
which is similar to the unique feature of Unilatus. While the
MCO in C. falsunilatum has a cork-screw-like shape, the
MCO in the new species is formed by a spiral tube with scle-
rotized walls. The new species differs from C. undulatum
n. sp. regarding the lengths of the MCO and accessory piece:
in the new species, the accessory piece is straight and elon-
gated, such that it goes beyond the base of the cirrus, while
in C. undulatum it is also straight, but only reaches just less than
half of the length of the MCO. The new species also differs
from all congeneric species in terms of the morphology of
the hooks, which are distally slender, expanded in the middle
third, and taper abruptly proximally.
Cosmetocleithrum ludovicense n. sp.
(Fig. 3)
urn:lsid:zoobank.org:act:2733EAE7-3CF5-4BBD-804A-
12852B7348E7.
Type-host: Platydoras brachylecis Piorski, Garavello, Arce
H & Sabaj Pérez, 2008 (Siluriformes, Doradidae).
Site in host: Gill lamellae.
Type-locality: Marketplace of the Cidade Operária, São
Luís, State of Maranhão, Brazil (2°34018.000S44°11049.900W).
Parasitological indexes: Total number of hosts: 3; number
of infected hosts: 3; total number of parasites: 434.
Type-material: Holotype CHIOC 40251; Paratypes CHIOC
40252 a–c; 40253 a–q.
Etymology: The specific name is in honor of people born
on São Luís Island, state of Maranhão, Brazil.
Description
Based on 25 specimens: 20 mounted in Hoyer’s medium
and 5 stained in Gomori’s trichrome. Body fusiform, elongated,
comprising cephalic region, trunk, peduncle and haptor. Body,
including haptor, 510 (310–630; n= 20) long by 119 (50–170;
n= 20) width at level of germarium. Tegument thin, smooth.
Cephalic lobes poorly developed. Four bilateral pairs of head
organs. Cephalic glands indistinct. Eyes absent. Accessory
granules sometimes scattered in the pharyngeal region. Mouth
subterminal. Pharynx spherical, weakly muscular 36 (33–50;
n= 12) in diameter. Esophagus short. Two intestinal ceca con-
fluent just posteriorly to testis, lacking diverticula. Gonads
intercecal, tandem. Germarium 35 and 63; long by 22 and
40 wide. Vagina well-developed, formed by two chambers with
heavily sclerotized walls that come together to form an opening;
vaginal canal very long, and convoluted, making some loops in
the direction of MCO. Seminal receptacle small, slightly
rounded. Mehlis’gland, uterus, oviduct and ootype not
observed. Vitellaria extends throughout the trunk, except in
areas of other reproductive organs. Testis postgermarial
31 (21–38; n=4)longby21(15–30; n= 4) wide. Vas deferens
looping left intestinal cecum; seminal vesicle a dilatation of vas
deferens. Prostatic reservoir pyriform. Copulatory complex
comprising MCO and accessory piece. MCO a sclerotized tube,
inverted J-shaped, 57 (47–67; n= 23) in total length; distal part
formed by a small and delicate tube, presenting a cap through
which its tip penetrates. MCO base irregularly expanded, with
an oval sclerotized brim associated with the base and a conspic-
uous rod-shape flange. Accessory piece straight and robust, with
a hollow structure and sclerotized walls, 40 (33–44; n=23)
long, non-articulated to the base of the MCO. Peduncle short.
Haptor, subhexagonal, with dorsal, ventral anchor/bar complex,
94 (45–130; n= 15) wide. Hooks with ancyrocephaline distribu-
tion. Anchors similar in shape and size, with well-developed
roots. Ventral anchor with elongate and truncated superficial
root and short deep root, straight shaft and long point; point
passing tip of superficial root, outer 23 (21–25; n= 23); inner
16 (12–20; n=23);base16(10–20; n= 23). Dorsal anchor with
elongated and pointed superficial root and short deep root,
straight shaft and long point; point passing tip of superficial root,
outer 23 (21–25; n= 23); inner 15 (13–18; n=23);base15
(13–18; n= 23). Ventral and dorsal bar open V-shaped, with
a fracture of the medium region. Ventral bar 48 (20–65;
n= 23) wide. Dorsal bar with two submedial projections,
43 (20–59; n= 24) wide. Hooks similar in size and shape, all
of them comprising a curved base, slender shank, rounded and
protruding thumb, curved shaft and short point 14 (12–15;
n= 77) long; FH loop almost the total shank length.
Remarks
Cosmetocleithrum ludovicense n. sp. is closely related to
Cosmetocleithrum confusus and to Cosmetocleithrum sobrinus
Kritsky, Thatcher & Boeger, 1986 regarding the enlarged base
of the MCO. However, it differs from these species in terms of
the shape of the accessory piece, which in C. confusus is a
hollow structure with sclerotized walls and truncated end, and
in C. sobrinus is large, globose and apparently hollow, while
in the new species, the MCO is formed by a thin hollow tube
of inverted J-shaped, with sclerotized walls. The new species
is also closer to Cosmetocleithrum akuanduba,inwhichthe
MCO has a tubular coiled shaft that frequently appears to have
an inverted J-shaped but differs from the latter in terms of its
sclerotized and bulbous base in the latter.
Cosmetocleithrum sacciforme n. sp.
(Fig. 4)
urn:lsid:zoobank.org:act:E6C1543F-3AA1-438A-8AF7-
12CDE13180F5.
Type-host: Oxydoras niger (Valenciennes, 1821) (Siluri-
formes, Doradidae).
6Silva A.L.S. et al: Parasite 2023, 30,53
Figure 3. Cosmetocleithrum ludovicense n. sp. from Platydoras brachylecis. (A) Total, ventral view (composite); (B) Copulatory complex,
ventral view; (C) Vagina; (D) Hook; (E) Dorsal bar; (F) Ventral bar; (G) Ventral anchor; (H) Dorsal anchor. Scale bars: A, 100 lm, B, C,
20 lm, D–H, 10 lm.
Silva A.L.S. et al: Parasite 2023, 30,53 7
Figure 4. Cosmetocleithrum sacciforme n. sp. from Oxydoras niger. (A) Total, ventral view (composite); (B) Copulatory complex, ventral
view; (C) Dorsal bar; (D) Ventral bar; (E) Hook; (F) Ventral anchor; (G) Dorsal anchor. Scale bars: A, 100 lm, B, E, 10 lm, C, D, F, G,
20 lm.
8Silva A.L.S. et al: Parasite 2023, 30,53
Site in host: Gill lamellae.
Type-locality: Juruá River, Acre, Brazil (7°40034.100S,
72°39039.500W).
Parasitological indexes: Total number of hosts: 7; number
of infected hosts: 2; total number of parasites: 7.
Specimens deposited: Holotype CHIOC 40254; Paratypes
CHIOC 40255 a–b; 40256 a–d.
Etymology: The specificnameisfromLatin(saccus = sac;
formis = shape of) and refers to the shape of accessory piece,
which resembles a sac-like structure.
Description
Based on 7 specimens mounted in Hoyer’s medium. Body
fusiform, robust, comprising cephalic region, trunk, peduncle
and haptor. Body length, including haptor, 530 (370–660;
n= 7) by 184 (70–230; n= 7) width at the level of germarium.
Tegument thin, smooth. Cephalic margin broad; cephalic lobes
moderately developed; three bilateral pairs of head organs;
cephalic glands posterolateral to pharynx. Eyes absent. Acces-
sory granules sometimes scattered in the pharyngeal region.
Mouth subterminal. Pharynx spherical, muscular 38 (25–50;
n= 4) in diameter. Esophagus short. Two intestinal ceca
confluent just posteriorly to testis, lacking diverticula. Gonads
intercecal, tandem. Germarium 111 (88–133; n= 5) long by
53 (43–60; n= 5). Vagina not observed; vaginal canal short
with aperture sinistroventral. Seminal receptacle rounded.
Mehlis’gland, uterus, oviduct and ootype not observed.
Vitellaria extends throughout the trunk, except in areas of other
reproductive organs. Testis postgermarial 119 (100–137; n=5)
long by 63 (52–80; n= 5) wide. Vas deferens looping left
intestinal cecum; seminal vesicle a dilatation of vas deferens.
Prostatic glands forming a dense mass around of the prostatic
reservoir. Prostatic reservoir piriform. Copulatory complex
comprising MCO and accessory piece. MCO formed by a
sclerotizedtubeslightlyflattened and twisted with the same
thickness over its entire length 48 (42–55; n= 7) in total length.
Accessory piece formed by a single plate of saccular appear-
ance with apparently membranous walls 23 (12–31; n=7);
MCO base with a conspicuous flap, 22 (21–23; n= 3) long.
Peduncle very short. Haptor subhexagonal, with dorsal, ventral
anchor/bar complex 117 (60–150; n= 7) wide. Hooks with
ancyrocephaline distribution. Anchors similar in shape and size,
deep and superficial roots well-developed, shaft curved, point
straight. Ventral anchor outer 31 (30–32; n=6);inner19
(17–21; n= 6); base 18 (17–20; n= 6). Dorsal anchor outer
31 (30–32; n= 6); inner 21 (20–22; n= 6); base 18 (17–19;
n= 6). Ventral bar open V-shaped with tapered ends,
60 (54–67; n= 6) wide. Dorsal bar V-shaped, with two subme-
dial long projections directed posteriorly, 65 (45–82; n=6).
Hooks similar in shape and size, with erect thumb, straight
shaft, and point; shank bent back proximally 16 (15–17;
n= 35). FH loop almost the total shank length.
Remarks
Cosmetocleithrum sacciforme n. sp. differs from all con-
generic species mainly in terms of the morphology of the acces-
sory piece, which is formed by a single plate of saccular
appearance. The new species is similar to C. bifurcum
Mendoza-Franco, Mendoza-Palmero & Scholz, 2016 with
regard to the presence of a dense mass of prostatic glands in
the anterior trunk but differs in the morphology of the anchors
and copulatory complex.
Cosmetocleithrum basicomplexum n. sp
(Fig. 5)
urn:lsid:zoobank.org:act:EEAF4C09-5CB9-492B-946A-
27D665D790B7.
Type-host: Oxydoras niger (Valenciennes, 1821) (Siluri-
formes, Doradidae).
Site in host: Gill lamellae.
Type-locality: Juruá River, Acre, Brazil (7°40034.100S,
72°39039.500W).
Parasitological indexes: Total number of hosts: 7; number
of infected hosts: 2; total number of parasites: 30.
Specimens deposited: Holotype CHIOC 40249 a; Paratypes
CHIOC 40249 b–q; 40250.
Etymology: The specific name is from Latin (basis =base;
complexum = complex) and refers to the ornamentation that
almost surrounds the base of the MCO.
Description
Based on 23 specimens: 15 mounted in Hoyer’s medium
and 8 stained in Gomori’s trichrome. Tegument thin, smooth.
Body fusiform, very elongated, comprising cephalic region,
trunk, peduncle, and haptor. Body length, including haptor,
2,768 (2,100–3,800; n= 23) by 531 (300–1,350; n= 23) width
at the level of germarium. Cephalic lobes poorly developed.
Three bilateral pairs of head organs. Cephalic glands posterolat-
eral to pharynx. One pair of eyes. Mouth subterminal. Pharynx
subspherical, muscular 175 (135–250; n= 20) by 302
(130–430; n= 20) wide. Esophagus short. Two intestinal ceca
confluent just posteriorly to testis, lacking diverticula. Gonads
intercecal, testes dorsal to germarium. Germarium 196 (180–
235; n= 9) long by 177 (100–185; n= 9). Vagina formed
by two chambers; vaginal aperture sinistroventral. Seminal
receptacle indistinct. Mehlis’gland, uterus, oviduct and ootype
not observed. Vitellaria extends throughout the trunk, except in
areas of other reproductive organs. Testis postgermarial 908
(775–1,025; n= 9) long by 152 (125–205; n= 9) wide. Vas
deferens looping left intestinal cecum; seminal vesicle a dilata-
tion of vas deferens. Prostatic reservoir present. Copulatory
complex comprising MCO and accessory piece. MCO a sclero-
tized coiled tube, with wide base opening, 70 (62–82; n=14)in
total length. Straight and robust accessory piece, with an appar-
ently hollow structure and sclerotized walls, serving as a guide
for the MCO 76 (62–90; n= 14); MCO base broad and sclero-
tized edges approximately the length of the MCO 77 (50–60;
n= 14) long. Peduncle very long. Haptor subhexagonal, very
small in relation to the body, with dorsal, ventral anchor/bar
complex 269 (155–490; n= 22) wide. Hooks with ancyro-
cephaline distribution. Anchors dissimilar in shape, deep
and superficial roots well-developed, shaft curved, point
straight. Ventral anchor outer 51 (47–55; n= 14) long; inner
25 (20–30; n=14);base37(32–42; n= 14). Dorsal anchor
Silva A.L.S. et al: Parasite 2023, 30,53 9
outer 51 (48–55; n= 14) long; inner 25 (20–38; n= 14); base
35 (32–38; n= 14). Ventral bar thin, V-shaped with midline
grooves 102 (80–130; n= 14) wide. Dorsal bar thin and fragile
W-shaped or arch-shaped, tapering in the medial region from
where a small and very fragile projection emerges, often almost
imperceptible 108 (87–126; n= 7) wide. Hooks similar in shape
and size, thumb short, depressed, shaft strongly robust through
its length, tapered abruptly in the final portion of the shaft,
forming a small pointed structure 20 (18–21; n=42).FHloop
almost the total shank length.
Figure 5. Cosmetocleithrum basicomplexum n. sp. from Oxydoras niger. (A) Total, ventral view (composite); (B) Copulatory complex,
ventral view; C) Vagina; (D) Dorsal bar; (E) Ventral bar; (F) Hook; (G) Dorsal anchor; (H) Ventral anchor. Scale bars: A, 50 lm, B, 40 lm,
C, G, H, 20 lm, D, E, 30 lm, F, 10 lm.
10 Silva A.L.S. et al: Parasite 2023, 30,53
Remarks
Cosmetocleithrum basicomplexum n. sp is more closely
related to C. confusus,C. sacciforme and C. ludovicense regard-
ing the enlarged base of the MCO, but differs from the first two
in terms of the morphology of the accessory piece. In the new
species, this is straight, with an apparently hollow structure
and sclerotized walls opening from half its length, while in
C. confusus it is a hollow structure with sclerotized walls and
truncated termination and in C. sacciforme it is sac-shaped with
apparently membranous walls. The new species closely resem-
bles C. ludovicense n. sp. regarding the morphology of the
copulatory complex (i.e. MCO and accessory piece) but differs
in terms of the shape of anchors and bars. Cosmetocleithrum
basicomplexum n. sp. shares morphological characteristics with
C. gigas Morey, Cachique & Babilonia, 2019 regarding the
body size and anchor shape but can be differentiated mainly
by the morphology of bars. In addition, the hooks of C. basicom-
plexum n. sp. has a shaft that is strongly robust throughout its
length, with a small constricted point, as was observed in the
hooks of C. undulatum.
Cosmetocleithrum akuanduba Soares,
Neto and Domingues, 2018 (Figs. 6A–6B)
Type-host: Hassar gabiru Birindelli, Fayal & Wosiacki,
2011.
Type-locality: Ilha grande, Xingu River, municipality of
Altamira, Pará, Brazil.
Other records: Brazil, Hassar affinis (Steindachner, 1881)
Marketplace of the Cidade Operária, São Luís, State of
Maranhão (2°34018.000S44°11049.900 W) (present study);
H.gabiru from Iriri River, and Bacajá River, municipality of
Altamira, Pará; H. orestis (Steindachner, 1875) from Xingu
River, Belo Monte Community, municipality of Vitória do
Xingu, Pará [21].
Parasitological indexes: Total number of hosts: 1; number
of infected hosts: 1; total number of parasites: 15.
New data
Based on 12 specimens mounted in Hoyer’s medium: Body
length, including haptor, 560 (480–650; n= 6) by 110 (90–130;
n= 6) width at the level of germarium. Tegument thin, smooth.
Eyes and accessory granules absent. Pharynx spherical, muscu-
lar 48 (32–65; n= 6) in diameter. Esophagus short. Gonads
intercecal, tandem. Testis postgermarial. Copulatory complex
comprising MCO and accessory piece. MCO consists of a thin
tube forming a semi-ring in a counter-clockwise orientation,
J-shaped 94 (79–116; n= 12) in total length. Accessory piece
formed by a straight rod, presenting a small gutter in the distal
portion serving as a guide for the MCO 31 (21–37; n=12)
long. Haptor subhexagonal, with dorsal, ventral anchor/bar
complex, 90 (70–120; n= 9) wide. Anchors similar in shape
and size, both of them comprising inconspicuous superficial
and deep roots, curved shaft and long and slightly curved point;
point acute passing the level of superficial root tip. Ventral
anchor with acute superficial root tip 25 (22–29; n= 10) inner;
32 (31–34; n= 10) outer; base 20 (15–24; n= 10) wide; Dorsal
anchor with rounded superficial root tip, 26 (23–29; n=10)
inner; 32 (30–35; n= 10) outer; base 19 (14–22; n= 10) wide.
Ventral bar slightly arcuate with delicate fracture hatches at
medial region and rounded ends 54 (47–63; n= 10) wide. Dor-
sal bar arcuate, V-shaped, with rounded ends and two subme-
dial long projections directed posteriorly 58 (40–66; n=10).
Hooks with ancyrocephaline distribution, similar in shape and
size; non-dilated shank, 14 (13–15; n= 28) long.
Remarks
According to Soares et al. [21], C. akuanduba is character-
ized mainly by the J-shaped MCO; elongated accessory piece
with sharp distal region, distal portion with a small gutter and
by the heavily sclerotized vagina with short S-shaped vaginal
canal. The specimens studied herein were conformable with
the original description, with small differences in the size of
the MCO and accessory piece, which in the present study were
larger than the specimens described by Soares et al.:[MCO94
(79–116); accessory piece 31 (21–37) in the present study vs
MCO 68 (54–76); accessory piece 23 (18–30)] in Soares
et al. [21].
Cosmetocleithrum confusus Kritsky,
Thatcher & Boeger, 1986 (Figs. 6C–6D)
Type-host: Oxydoras niger (Valenciennes), Doradidae.
Type-locality: Janauacá Lake near Manaus, Amazonas,
Brazil.
Other records: Brazil, Oxydoras niger from Jurua River,
State of Acre (7°40034.100S, 72°39039.500 W) (present study);
Janauacá Lake, near Manaus, Amazonas State [10]; basin of
Solimões River, Amazonas state [20]; Peru, Amazonas River,
Iquitos [9].
Parasitological indexes: Total number of hosts: 7; number
of infected hosts: 2; total number of parasites: 9.
New data
Based on 11 specimens mounted in Hoyer’s medium. Body
fusiform, elongated, comprising cephalic region, trunk, pedun-
cle, and haptor. Body length, including haptor, 883 (620–1040;
n= 11) long by 158 (81–185; n= 11) wide, width at the level of
germarium. Tegument thin, smooth. Copulatory complex com-
prising MCO and accessory piece. MCO formed by a coiled
sclerotized tube, poorly defined coil, 67 (54–93; n= 11)) in
total length, counter-clockwise orientation. Accessory piece
64 (57–75; n= 11) long, non-articulated with MCO, with a
proximal portion very tapered and a hollow bulbous portion
in the distal region Haptor subhexagonal. Anchors similar in
shape; elongate point, short small base; ventral anchor, 31
(31–34; n= 10) long, base 23 (20–35; n= 10); dorsal anchor,
32 (32–39; n=10),base24(22–35; n= 10). Ventral bar
V-shaped 85 (72–105; n= 10) long. Dorsal bar V-shaped,
with two submedial long projections directed posteriorly
88 (105–87; n= 10) long. Hooks similar in shape and size,
tapered shaft and point thumb, straight depressed thumb,
slender shank 16 (13–17; n=40).
Silva A.L.S. et al: Parasite 2023, 30,53 11
Remarks
The morphology of C. confusus from the present study is in
agreement with the original description of Kritsky et al. [10],
differing only in relation to total body length and bars length,
which in the present study were greater than in the specimens
described by Kritsky et al.: body length 883 (620–1,040) long
by 158 (81–185) wide, ventral bar 85 (72–105) long and dorsal
bar 88 (105–87) long, in the present material vs body length 564
(449–706) long by 158 (81–185) wide, dorsal bar 53 (47–62)
Figure 6. (A, B) Cosmetocleithrum akuanduba Soares, Neto and Domingues, 2018: (A) Male copulatory organ; (B) Haptor structures; (C, D)
Cosmetocleithrum confusus Kritsky, Thatcher and Boeger, 1986: (C) Male copulatory organ; (D) Haptor structures; (E)–(G) Cosmetocleithrum
leandroi Soares, Neto and Domingues, 2018: (E) Male copulatory organ; (F) Egg; (G) Haptor structures. Scale bars: A, 20 lm, B, D, F, G,
40 lm, C, 30 lm, E, F, 50 lm.
12 Silva A.L.S. et al: Parasite 2023, 30,53
long and ventral bar 59 (47–74) long in the material of Kritsky
et al. [10].
Cosmetocleithrum leandroi Soares,
Neto & Domingues, 2018 (Figs. 6E–6F)
Type-host: Hassar gabiru Birindelli, Fayal & Wosiacki,
2011, Doradidae.
Type-locality: Bacajá River, municipality of Altamira, Pará,
Brazil.
Others records: Brazil, Hassar affinis (Steindachner, 1881)
from Market-place of the Cidade Operária, São Luís, State of
Maranhão (2°34018.000S44°11049.900 W) (present study);
H. gabiru from Ilha Grande, Xingu River, and Iriri River,
municipality of Altamira, Pará [21].
Parasitological indexes: Total number of host: 1; number of
infected hosts: 1; total number of parasites: 93.
New data
Based on 13 specimens mounted in Hoyer’s medium. Body
fusiform, elongated, comprising cephalic region, trunk, pedun-
cle, and haptor. Body length, including haptor, 933 (650–1,250;
n= 13) long by 119 (110–175; n= 13) wide width at the level
of germarium. Tegument thin, smooth. Eyes and accessory
granules absent. Pharynx spherical, muscular 62 (50–80;
n= 8) in diameter. Vagina heavily sclerotized, vaginal pore
sinistroventral; vaginal canal very long, convoluted, looping
towards the MCO. Copulatory complex comprising MCO
and accessory piece. MCO formed by a coiled sclerotized tube
with a bulbous structure in the distal region 612 (546–664;
n= 7) in total length, with 3½ to 4½ counter-clockwise rings.
Accessory piece 112 (98–138; n= 13) long, not articulated with
MCO, comprising a sigmoid rod, with cup-shaped distal region.
Peduncle long. Haptor subhexagonal, 109 (110–175; n=10)
wide. Ventral anchors with pointed superficial root and deep
root broad, slightly curved shaft and point, outer 47 (44–50;
n= 13) long, inner 34 (31–39; n= 13), base 30 (24–33;
n= 13); dorsal anchor, with pointed superficial root and deep
root short, slightly curved shaft and point, outer 37 (31–43;
n= 13), inner 33 (29–36; n= 13), base 23 (20–30; n=13).
Ventral bar straight with knobbed ends 49 (42–55; n= 13) long,
by 6 (5–10; n= 13) wide. Dorsal bar straight, with two subme-
dial long projections directed posteriorly 55 (50–65; n=13)
long by 7 (5–8; n= 13). Hooks similar in shape and size, incon-
spicuous rounded thumb, shaft straight, short, slightly dilated
15 (14–15; n= 40). Egg oval, with filament opposite to opercu-
lar end, 84 (80–87; n=5)longby50(47–52; n=5)wide;
filamentous 58 (47–70; n=5).
Remarks
Cosmetocleithrum leandroi was described from the gill fil-
aments of Hassar gabiru, in the state of Pará, Brazil. According
to the original description, C. leandroi is characterized by a
MCO comprising a coil of about 3½ rings, a sigmoid accessory
piece with a cup-shaped distal portion, a single type of hooks,
and anchors with poorly differentiated roots. The speci-
mens studied here, based on newly collected specimens from
H. affinis, were in accordance with the original description,
while presenting some differences in morphology and measure-
ments, compared with the original material, deposited in CHIOC
(Holotype 39053 a, paratypes 39053 b–f, vouchers 39054 a–c):
body length 933 (650–1,250) long by 119 (110–175) wide,
MCO with 3½ to 4½ counter-clockwise rings, ventral and dorsal
anchors with pointed superficial root and deep root developed
and hooks with slightly dilated shank, in the present material
vs body length 712 (575–835) long by 132 (102–157) wide,
MCO with 3½ counter-clockwise rings, superficial and deep
roots poorly developed and hooks with non-dilated shank in
the original description and type material examined.
Discussion
Cosmetocleithrum is one of the most diverse genera of
dactylogyrids parasitizing neotropical catfishes [4]. It is charac-
terized by the presence of two submedial ribbon-like projec-
tions on the dorsal bar, a copulatory complex comprising a
variably coiled cirrus with counter-clockwise rings and an elab-
orate accessory piece non-articulated to the cirrus base [10].
So far, species of Cosmetocleithrum have been found in
fishes caught in Argentina (1), Brazil (18), and Peru (4). Among
these, 14 species parasitize hosts of the Doradidae: C. akuan-
duba,C. bifurcum,andC. leandroi parasitizing Hassar gabiru;
Cosmetocleithrum phryctophallus Soares, Santos Neto &
Domingues, 2018 parasitizing Hassar orestis (Steindachner);
C. confusus,Cosmetocleithrum gigas,C. gussevi Kritsky,
Thatcher & Boeger, 1986, Cosmetocleithrum parvum Kritsky,
Thatcher & Boeger, 1986, Cosmetocleithrum rarum Kritsky,
Thatcher & Boeger, 1986 and Cosmetocleithrum sobrinus
Kritsky, Thatcher & Boeger, 1986 parasitizing O. niger;Cosme-
tocleithrum tortum Mendoza-Franco, Mendoza-Palmero &
Scholz, 2016 parasitizing Nemadoras hemipeltis (Eigenmann),
Cosmetocleithrum infinitum Morey, Rojas & Cachique, 2022
parasitizing Anadoras grypus (Cope); C. falsunilatum parasitiz-
ing Megalodoras uranoscopus (Eigenmann & Eigenmann) and
Cosmetocleithrum trachydorasi (Acosta, Scholz, Blasco-Costa,
Alves, Silva & 2018) Cohen, Justo, Gen & Boeger, 2020
parasitizing Trachydoras paraguayensis (Eigenmann & Ward).
Cohen et al. [4] proposed two morphologically distin-
guished groups among the species of Cosmetocleithrum:(1)spe-
cies that resemble the type species, Cosmetocleithrum gussevi,
which present non-articulated bars and a distally bifid accessory
piece, often resembling a hook (C. parvum,C. rarum,C. sobri-
nus,Cosmetocleithrum longivaginatum Suriano & Incorvaia,
1995, C. striatuli,C. laciniatum,C. phryctophallus and
C. gigas); and (2) species with articulated bars and a variably
shaped accessory piece (e.g. C. confusus,C. bulbocirrus,
C. tortum and C. bifurcum). Subsequently, new species of
Cosmetocleithrum were proposed and can be placed in those
groups. Among these, C. berecae Cohen, Justo, Gen & Boeger,
2020, C. nunani Cohen, Justo, Gen & Boeger, 2020, C. falsuni-
latum Feronato, Razzolini, Morey & Boeger, 2022, C. galeatum
Yamada, Yamada & Silva, 2020, C. spathulatum Yamada,
Yamada & Silva, 2020 and C. baculum Yamada, Yamada &
Silva, 2020 were placed in group 1. In the description of Cosme-
tocleithrum infinitum,Moreyet al. [13] present images that
Silva A.L.S. et al: Parasite 2023, 30,53 13
showed the articulation on the ventral bar. Among the new
species proposed in the present study, only C. ludovicense and
C. sacciforme present articulated bars and thus are included in
group 2, while C. undulatum,C. brachylecis and C. basicom-
plexum are included in the group 1.
Nevertheless, in the phylogenetic analysis of Cosmetoclei-
thrum conducted by Mendoza-Palmero et al. [11], the phyloge-
netic position of the species analyzed corresponded partially to
the morphological categories proposed by Cohen et al. [4].
Their study [11] provides suggestions for further studies regard-
ing Cosmetocleithrum spp., including the molecular characteri-
zation of the remaining species of this genus in order to
evaluate the phylogenetic positions of all the species.
Mendoza-Palmero et al. [11] stated that more than 15 spe-
cies of Cosmetocleithrum have been described over recent
years, thereby adding new morphological characteristics that
can be included in the diagnosis of the genus. They cited
C. bifurcum (a member of the “doradid group”)andC. baculum
(a member of the “auchenipterid group”), which have dissimilar
hooks, but C. nunani (also a member of the auchenipterid
group) presents two morphologically distinct hooks. Regarding
the species described in the present paper, C. undulatum
(a member of the doradid group) can be included in this set
of species with two morphological distinct hooks, thus showing
that it is not related to the host family. Considering the position
of the vagina, a feature also mentioned by Mendoza-Palmero
et al. [11], the species described herein are concordant with
almost all species of the genus, presenting a sinistral aperture,
with the exception of C. tortum.
Despite the high diversity of catfish in the Amazon region
and the economic importance of some of these species, knowl-
edge of the helminth fauna parasitizing these fish is still frag-
mentary and far from sufficient [12]. Moreover, no studies on
the helminth fauna of many of these fish have yet been con-
ducted, as is the case of P. brachylecis, which is a thorny catfish
endemic to the basins of the Mearim River, Pindaré River,
Itapecuru River and Parnaíba River, in northeastern Brazil
[16]. The new species described in the present study and the
new records of hosts for P. brachylecis demonstrate that there
is a real need to expand such studies, especially with regard to
endemic fish species and those that have recently been
described. The finding, more than 30years later, of two new spe-
cies in O. niger, the type host of the first four species that were
proposed for Cosmetocleithrum, also demonstrates that studies
on these hosts are necessary and should take into consideration
the ecological processes related to the host-parasite association.
Acknowledgements. This work was supported by “Coordenação
de Aperfeiçoamento Técnico de Pessoal de Nível Superior/CAPES”
(finance cod 001, Process: 88887.707472/2022-00. “Programa
CAPES: PDPG Emergencial de Consolidação Estratégica dos Pro-
gramas de Pós-Graduação (PPGs)”Stricto sensu academics with
grades 3 and 4 and “Fundação de Amparo à Pesquisa e ao Desen-
volvimento Científico e Tecnológico do Maranhão”(grant number
UNIVERSAL-01148/18-, grant number BD-01172/20).
Conflict of interest
The authors declare that they have no conflicts of interest.
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Cite this article as: Silva ALS, Meneses YC, Martins WMO, Cohen SC, Costa AP & Justo MCN. 2023. Dactylogyrids (Platyhelminthes,
Monogenea) from the gill lamellae of doradids (Siluriformes) with description of five new species of Cosmetocleithrum and new
geographical distribution for known species from the Neotropical Region, Brazil. Parasite 30, 53.
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