Redescription and molecular analysis of Neoechinorhynchus (Neoechinorhynchus) planilizai (Acanthocephala, Neoechinorhynchidae) from Planiliza abu (Mugilidae) in Iraq
Neoechinorhynchus (N.) planilizai Al-Ayash, Gustinelli, Al-Nasiri, Caffara, 2021 was recently described from Planiliza abu (Heckel) in Iraq using line drawings. We update and complete that description using new ocular microscopy, SEM, and molecular analysis. New collections revealed structures t...
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| Veröffentlicht in: | Zoodiversity (Vestnik Zoologii) |
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| Datum: | 2026 |
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| author | Amin, O. M. Chaudhary , A. Caracciolo , M. E. Ali , A. H. Al-Kuraizy , M. H. Rubtsova, N. Y. Singh , H. S. |
| author_facet | Amin, O. M. Chaudhary , A. Caracciolo , M. E. Ali , A. H. Al-Kuraizy , M. H. Rubtsova, N. Y. Singh , H. S. |
| author_institution_txt_mv | [
{
"author": "O. M. Amin",
"institution": "Institute of Parasitic Diseases, Scottsdale, Arizona, USA",
"orcid": ""
},
{
"author": "A. Chaudhary ",
"institution": "Aquatic and Molecular Biology Laboratory, Department of Zoology, Chaudhary Charan Singh University, India",
"orcid": ""
},
{
"author": "M. E. Caracciolo ",
"institution": "Centro Multiusuário para Análises de Fenômenos Biomédicos (CMABio) Universidade Estadual do Amazonas (UEA), Brazil ",
"orcid": ""
},
{
"author": "A. H. Ali ",
"institution": "Department of Fisheries and Marine Resources, College of Agriculture, University of Basrah, Basrah, Iraq",
"orcid": "0009-0003-1184-9026"
},
{
"author": "M. H. Al-Kuraizy ",
"institution": "Department of Fisheries and Marine Resources, College of Agriculture, University of Basrah, Basrah, Iraq",
"orcid": ""
},
{
"author": "N. Y. Rubtsova",
"institution": "Institute of Parasitic Diseases, Scottsdale, Arizona, USA",
"orcid": ""
},
{
"author": "H. S. Singh ",
"institution": "Aquatic and Molecular Biology Laboratory, Department of Zoology, Chaudhary Charan Singh University, Uttar Pradesh, India",
"orcid": ""
}
] |
| author_orcid_str_mv | 0009-0003-1184-9026 |
| author_sort | Amin, O. M. |
| baseUrl_str | https://ojs.akademperiodyka.org.ua/index.php/Zoodiversity/oai |
| collection | OJS |
| container_end_page | |
| container_issue | 4 |
| container_start_page | |
| container_title | Zoodiversity (Vestnik Zoologii) |
| container_volume | 60 |
| datestamp_date | 2026-08-26T09:51:17Z |
| description |
Neoechinorhynchus (N.) planilizai Al-Ayash, Gustinelli, Al-Nasiri, Caffara, 2021 was recently described from Planiliza abu (Heckel) in Iraq using line drawings. We update and complete that description using new ocular microscopy, SEM, and molecular analysis. New collections revealed structures that have not been previously reported including constricted proboscis, posterior hooks longer than middle hooks, bursa without sensory structures, spongy hypodermic tissue with lacunar channels under smooth cuticular surface, eggs with no fibrils, variable micropores, single ventral para-receptacle structure, large triangulate cephalic ganglion, a new papilla at the posterior tip of the proboscis receptacle, an anterior testis distinctly longer than posterior testis, short robust uterus a huge pot-shaped uterine bell, and two sets of ligament bundles emerging from the inner posterior tip of the trunk. No other taxonomic accounts of this species are known. The molecular analysis of N. planilizai is also described with sequences of the 18S nuclear ribosome generated and aligned with closely related sequences from GenBank database. Maximum likelihood and Bayesian inference analyses demonstrated that N. (N) planilizai was nested within neoechinorhynchid clades. Th e presence of N. (N) planilizai with other Middle East species in the tree allowed its characterization for the first time using morphological and molecular features.
|
| doi_str_mv | 10.15407/zoo2026.04.405 |
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| first_indexed | 2026-08-27T01:00:42Z |
| format | Article |
| fulltext |
DOI 10.15407/zoo2026.04.405
UDC 576.895.121:597.556.331
REDESCRIPTION AND MOLECULAR ANALYSIS
OF NEOECHINORHYNCHUS (NEOECHINORHYNCHUS)
PLANILIZAI (ACANTHOCEPHALA,
NEOECHINORHYNCHIDAE)
FROM PLANILIZA ABU (MUGILIDAE) IN IRAQ
O. M. Amin ¹, *, A. Chaudhary 2, M. E. Caracciolo 3, A. H. Ali 4,
M. H. Al-Kuraizy 4, N. Y. Rubtsova ¹ & H. S. Singh 2
¹ Institute of Parasitic Diseases, 11445 E. Via Linda, # 2-419, Scottsdale, Arizona 85259, USA
2 Aquatic and Molecular Biology Laboratory, Department of Zoology,
Chaudhary Charan Singh University, Meerut-250004, Uttar Pradesh, India
3 Centro Multiusuário para Análises de Fenômenos Biomédicos (CMABio)
Universidade Estadual do Amazonas (UEA), Brazil
4 Department of Fisheries and Marine Resources, College of Agriculture,
University of Basrah, Basrah, Iraq
E-mail: omaramin@aol.com
O. M. Amin (http://orcid.org/0000-0003-2088-8628)
urn:1sid:zoobank.org: act: FF60A87E-10F7-41D2-B1EB-26A53C66ED33
Redescription and molecular analysis of Neoechinorhynchus (Neoechinorhynchus)
planilizai (Acanthocephala, Neoechinorhynchidae) from Planiliza abu (Mugilidae)
in Iraq. Amin, O. M., Chaudhary, A., Caracciolo, M. E., Ali, A. H., Al-Kuraizy, M. H.,
Rubtsova, N. Y. & Singh, H. S. — Neoechinorhynchus (N.) planilizai Al-Ayash, Gustinelli,
Al-Nasiri, Caffara, 2021 was recently described from Planiliza abu (Heckel) in Iraq using line
drawings. We update and complete that description using new ocular microscopy, SEM, and
molecular analysis. New collections revealed structures that have not been previously report-
ed including constricted proboscis, posterior hooks longer than middle hooks, bursa without
sensory structures, spongy hypodermic tissue with lacunar channels under smooth cuticu-
lar surface, eggs with no fibrils, variable micropores, single ventral para-receptacle structure,
large triangulate cephalic ganglion, a new papilla at the posterior tip of the proboscis recep-
tacle, an anterior testis distinctly longer than posterior testis, short robust uterus a huge pot-
shaped uterine bell, and two sets of ligament bundles emerging from the inner posterior tip
of the trunk. No other taxonomic accounts of this species are known. The molecular analysis
of N. planilizai is also described with sequences of the 18S nuclear ribosome generated and
Parasitology Zoodiversity, 60(4): 405–421, 2026
© Publisher Publishing House “Akademperiodyka” of the NAS of Ukraine, 2026. The article is
published under an open access license CC BY-NC-ND (https://creativecommons.org/licenses/
by-nc-nd/4.0/)
ISSN 2707-725X. Zoodiversity. 2026. Vol. 60, No. 4
O. M. Amin, A. Chaudhary, M. E. Caracciolo et al.
ISSN 2707-725X. Zoodiversity. 2026. Vol. 60, No. 4
406
aligned with closely related sequences from GenBank database. Maximum likelihood and
Bayesian inference analyses demonstrated that N. (N) planilizai was nested within neoechi-
norhynchid clades. The presence of N. (N) planilizai with other Middle East species in the tree
allowed its characterization for the first time using morphological and molecular features.
Key words: scanning electron microscopy, 18S rDNA, phylogenetic relationships, para-receptacle
structure, Tigris River, fish parasites.
Introduction
Neoechinorhynchus (N.) planilizai Al-Ayash, Gustinelli, Al-Nasiri, Caffara, 2021 has
been rarely reported since its morphological description from the Abu mullet Planiliza
abu [Heckel] (Mugilidae) and infrequently from the Tigris catfish Silurus triostegus
[Heckel] (Siluridae) by Al-Ayash (2021). It was first erroneously reported as N. lizai
from P. abu by Al-Ayash (2020) in the Tigris River and from Silurus triostegus by Al-
Ayash (2020) in his unpublished Ph. D. thesis and later formally by Al-Ayash et al.
(2021). The description and 8 lines drawings in both accounts were very similar but
the dissertation additionally included 15 uninformative microscopic images.
In his dissertation, Al-Ayash (2020) reported N. planilizai from 17.7% of S. tri-
ostegus and from 95.5% of P. abu. Silurus triostegus was infected with a large number
of endohelminth parasites including 20 trematode species, 16 cestodes, 8 nematodes
and seven acanthocephalans including Echinorhynchus sp., Neoechinorhynchus ira
qensis Amin, Al-Sady, Mhaisen and Bassat, 2001, N. planilizai (reported as N. lizai),
N. rutili (Müller, 1780) Hamann, 1892, N. zabensis Amin, Abdullah, Mhaisen, 2003,
Neoechinorhynchus sp. and Pomphorhynchus spindletruncatus Amin, Abdullah,
Mhaisen, 2003, (Mhaisen, Personal Comm.). In addition to the 3 new species of
Neoechinorhynchus Stiles and Hassall, 1905 described by Al-Ayash et al. (2021)
(N. barbi, N. planilizai, N. tigrisensis), they reported “additional” species of marine
and freshwater acanthocephalans. Amin et al. (2023) reviewed the acanthocephalan
species recorded from fishes off Iraq and pointed that some acanthocephalan species
so far recorded come from misidentification.
In the present research, specimens of Neoechinorhynchus planilizai was collected
from hosts in the Tigris River at Salah Al Din province, Iraq and characterize it by
using the morphology and molecular data to study the phylogenetic position within
the genus Neoechinorhynchus.
Material and Methods
C ol lec t ions
Originally, A total of 451 fish belonging to 16 species and 5 families were collected
from February to December, 2018 in the Tigris River at Salah Al Din province
between Tikrit city (34°25'39" N and 44°20'45" E) and Al-Dhuluiya city (34°20'44" N
and 44°15'40" E) north of Baghdad, mid Iraq. Sixty five of 68 (95%) and 6 of 34
(18%) individuals of P. abu and of S. triostegus, respectively, were infected with 361
and 15 specimens of N. iraqensis and N. planilizai, respectively (Al-Ayash, 2020;
Al-Ayash et al., 2021). Thirteen of the 68 P. abu individuals (19%) were also infec
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ted with 15 specimens of Neoechinorhynchus zabensis and 2 of the 34 examined
individuals of S. triostegus (6%) were infected with 3 specimens of Neoechinorhyn-
chus (N.) iraqensis.
Most recently in 2024, one of us (OA) received 929 acanthocephalans collected
from 274 of 884 examined individuals (31%) of P. abu (Table 1) in the Al-Gharraf
River, Thi Qar Province, southern Iraq (46°17'45" to 46°11'64" E and 31°44'60" to
31°58'74" N) collected between December 2022 and December 2023 (Table 1). These
specimens were mostly N. iraqensis but some belonged to N. planilizai.
Management of specimens
Whole mounted specimens of the first two collections were used for ocular micros-
copy images. Six specimens of the third collection were used for SEM, and three
specimens for molecular analysis.
Process ing for microscopy
Worms from representative samples of the original and subsequent collections
were stained in Mayer’s acid carmine, destained in 100% ethanol and 4% HCL,
dehydrated in ascending concentrations of ethanol, cleared in 100% xylene and
then in 50% xylene and 50% Canada balsam each for 24 hr. and whole mounted in
Canada balsam.
Table 1 . Collections of Neoechinorhynchus iraqensis and a few N. planilizai
from Abu mullet Planiliza abu (Heckel, 1843) in Al-Gharraf River,
Thi Qar Province, Southern Iraq
No Months, years Number
examined fish
Number
infected fish
Number
of parasite
Prevalence
of infection%
Intensity
of infection
1 December–2022 23 – – – –
2 January–2023 8 3 12 37.5 4.0
3 Feb–2023 16 2 4 12.5 2.0
4 March–2023 10 7 15 70.0* 21.4
5 April–2023 22 12 44 54.5 3.7
6 May–2023 103 76 464 73.8 6.1
7 June–2023 174 94 262 54.0 2.8
8 July–2023 94 39 69 41.5 1.8
9 August–2023 96 4 4 4.16 1.0
10 September–2023 90 13 13 14.1 1.0
11 October–2023 106 – – – –
12 November–2023 71 17 30 23.9 1.8
13 December–2023 71 7 12 9.9 1.7
Total or mean 884 274 929 31.0 3.4
*Extreme parameters are bolded.
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Deposit and reg istrat ion
Type specimens were deposited by Al-Ayash in the collection of the Institute of Para-
sitology, Academy of Sciences of the Czech Republic (IPCAS A-124). ZooBank regis-
tration: urn:1sid:zoobank.org: act: FF60A87E-10F7-41D2-B1EB-26A53C66ED33.
Opt ica l microscopy
Images created for this presentation using optical microscopy were acquired using a
Zeiss Axioskop Transmitted Nomarski DIC Phase Contrast Microscope Trinocular
(Munich, Germany) and a Canon T3i EOS 600D DSLR Camera (Melville, New
York). Images from the microscope were transferred from the laptop to a USB and
stored for subsequent processing on a computer.
S canning Elec tron Microscopy (SEM)
Fixed parasite specimens in 70% ethanol were prepared following established proto-
cols (Lopes Torres et al., 2013), which included sequential dehydration through an
ethanol gradient (70% — absolute), critical point drying LEICA EM CPD 300 (Leica
Microsystems, Wetzlar, Germany), and subsequent mounting on alumimium stubs
using conductive double-sided carbon tape. Eggs samples were extracted from fixed
adult females and adhered to glass coverslips using bovine skin gelatin (Sig-
ma-Aldrich, St. Louis, Missouri, USA), then processed using the same protocol ap-
plied to the parasite specimens. All samples were sputter-coated with a gold layer
approximately 20 nm in thickness using a DII-29010SCTR Smart Coater (JEOL, Ak-
ishima, Japan). Observations were performed using a JEOL JSM-IT500HR SEM
(JEOL, Akishima, Japan). Images were taken at various magnifications. Samples
were received under an acceleration voltage of 10 kV.
Exper imenta l protocol
Fish were collected periodically in the field using seins then transferred on ice to
the laboratory in the same day for processing. They were subsequently anesthetised
before the intestinal tracks were removed for dissection, with a longitudinal slit,
and parasite recovery. Acanthocephalans were placed in refrigerated water over
night or until the proboscides were everted then placed in cold 70% ethanol for
fixing and transport.
Molecular methods
Two specimens of N. planilizai that were placed in tubes and stored at –20 ºC were
used for the DNA extraction. The genomic DNA was extracted using DNeasy Blood
and Tissue kit (Qiagen) according to the manufacturer’s instructions. The 18S region
of nuclear ribosomal DNA (rDNA) was amplified by polymerase chain reaction
(PCR). The forward and reverse primers for the 18S gene were Worm A and 1270R
and 930F and Worm B (Littlewood and Olson, 2001) respectively. PCR reactions
(25 μl) consisted of 1.2 μl of each primer, 2.5 μl of 10 X buffer with MgCl2, 2.0 μl of
dNTPs (10 mM), 1 U of Taq DNA polymerase (Invitrogen) with 3.5 μl of the genom-
ic DNA and 13.6 μl of distilled water. The PCR cycling parameters for 18S rDNA
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amplifications were followed as: denaturation at 94 °C for 3 minutes; 30 cycles of
94 °C for 1 minute; annealing at 56 °C for 50 seconds and an extension at 72 °C for 1
minute with a final extension at 72°C for 7 minutes. The sequencing reactions were
performed using an ABI BigDye Terminator Kit (Applied Biosystems, USA) and
amplification reaction products were detected using an ABI 3730 capillary DNA Se-
quencer. The 18S sequences were assembled using Codoncode Aligner version 5.1.2.
The sequences generated for 18S were aligned with other sequences downloaded
from GenBank database (available on https://www.ncbi.nlm.nih.gov/). Polyacantho-
rhynchus Travassos, 1920 was used as the outgroup. Sequences for 18S molecular
marker were aligned by the software Clustal W with default parameters implement-
ed in MEGA version 11 (Tamura et al., 2021). The Akaike Information Criterion
(AIC) implemented in MEGA version 11 was used to detect the best-fitting nucleo-
tide substitution model and GTR + G + I was estimated as the best model. The 18S
phylogenetic analyses were run using the maximum likelihood (ML) and Bayesian
Inference (BI) methods using MEGA version 11 and TOPALi version 2.5 (Milne et
al., 2009) respectively. ML tree 10,000 bootstrap replicates were run to evaluate nod-
al support. For BI analysis, running two independent Markov Chain Monte Carlo
(MCMC) chains runs of four chains each for 106 generations, with sampling every
1000 generations with a burn-in of 25%. The genetic divergence among taxa was
assessed using uncorrected ‘p’ distances in MEGA version 11. The accession num-
bers for the sequences generated here for 18S rRNA gene have been deposited in
NCBI GenBank with the following accession numbers: PX506235, and PX506229.
Results
The structures and measurements of our newly collected specimens of N. planilizai
were comparable to those in the original description by Al-Ayash et al. (2021, p. 671)
that were, however, incomplete and inadequately documented. Our account of the
anatomical structures was generally similar but much more detailed and restruc-
tured compared to their line drawings figures 2A–G (p. 672), with marked varia-
tions. We describe new morphological and anatomical observations of structures
that were not reported in the original description constituting a redescription of
N. planilizai. In addition to the original measurements and inadequate description,
we redescribe below our new observations of the external morphology of specimens
using SEM (Figs 1, a–f; 2, a–f) and the internal anatomy using ocular microscopy
(Figs 3, a–e; 4, a–c).
Morpholog y of N. plani lizai us ing SEM
The use of SEM revealed additional features not previously reported in the original
description and are herein described for the first time in figures 1, 2. Specimens were
long, smooth, thin and cylindrical, showing considerable sexual dimorphism in trunk
size, among other characters, with males reaching 28 mm long compared to females
reaching 80 mm long. In males, the proboscis was constricted between the middle and
posterior hooks; all hooks were deeply recessed (Fig. 1, a). The bulbous anterior pro-
boscis had hooks in two circles with the apical hook reaching 40 μm in length. The
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Fig. 1. SEM images of Neoechinorhynchus planilizai males collected from Planiliza abu in the
Tigris River, Iraq; a — the proboscis showing recessed hooks, a constriction between middle and
posterior hook circles, and the girdle. A sensory pore is marked with an arrow. Posterior hooks
are larger than middle hooks. Note depressions in the widening neck; b — another perspective
of the proboscis and neck marking different size hooks, proboscis constriction, and the girdle.
A sensory pore is marked with an arrow; c — a high magnification of a recessed apical hook; d —
a high magnification of a posterior hook; e — a sensory pore on the neck; & f — a ventral view of
the bursa showing no evidence of sensory structures
posterior proboscis fans out into the neck which depicts multiple sensory pores (ar-
rows) and is marked off the anterior trunk with a distinct cuticular thickening forming
the girdle (Fig. 1, a). Another perspective of the proboscis constriction and the girdle
(Fig. 1, b) also demonstrate the different size of the middle hooks compared to the
longer posterior hooks also demonstrated in fig. 1, a. These observations are in stark
contrast to the original description where the length of both middle hooks and poste-
f
d
b
e
c
a
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rior hooks were stated as equal at 13–19 (16) μm in length as also shown in their
Fig. 2, B; they measured 20 males. The apical end of the proboscis did not show the
depression that marks the position of the apical organ which is, however, present as
seen in microscopic images. An anterior hook deeply recessed in the proboscis
(Fig. 1, c) and a posterior hook (Fig. 1, d), and a neck sensory pore (Fig. 1, e, arrow) is
Fig. 2. SEM images of Neoechinorhynchus planilizai females collected from Planiliza abu in the
Tigris River, Iraq; a — a cross section in the anterior trunk showing the smooth surface, thin
cuticle (C) and disturbed hypodermis, a few eggs, and a section of the large lemniscus (L); b —
a highly magnified section of the body wall showing the cuticle (C), relatively thick hypodermis
(H), a lacunar channel (LC), and the muscular layer (M); c–d — micropores from the middle and
posterior region of the trunk, respectively. Note differences in pore diameter and distribution
corresponding with differential absorption of nutrients; e — a fully ripe egg with giant subcutane-
ous nuclei; f — a similar egg with intentionally broken shell to demonstrate the absence of fibrils
a
c
e
b
d
f
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Fig. 3. Ocular microscopy images of Neoechinorhynchus planilizai females collected from Planili-
za abu in the Tigris River, Iraq; a — The anterior portion of a female specimen showing the
relative size proportions of the proboscis (P), the much larger proboscis receptacle (PR) and
the ventrally adjacent para-receptacle structure (PRS), the huge large lemniscus (LL) with one
giant nucleus at that location, and one dorsal giant subcutaneous nucleus (GSN); b — a higher
magnification of the specimen in Fig. 3, a showing the proboscis receptacle (PR), para-receptacle
structure (PRS) cephalic ganglion (CG), a giant subcutaneous nucleus (GSN), and the lemniscus
(L). The arrow points to the apical organ; c — a higher magnification of another female specimen
emphasizing the retractor muscles (RM), the para-receptacle structure (PRS), the girdle (G), the
cephalic ganglion (CG), and the receptacle papillae (arrow); d — detail of the receptacle with
two sets of retractor muscles (RM), Para-receptacle structure (PRS), and cephalic ganglion (CG);
e — the male reproductive system including the anterior testis (AT), posterior testis (PT), cement
gland (CG), cement gland reservoir (CR), and sperm vesicle (SV)
a
c
e
b
d
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revealed. A basal view of a partially contracted bursa (Fig. 1, f) demonstrates its smooth
surface and the absence of any characteristic sensory structures.
Females had similar but slightly larger proboscis and hooks than males as shown
in our figures 1, a-d even though in the original description, the apical hooks were
smaller in females (21–35 μm long) compared to 22–40 μm long in males. The mor-
phology of the presoma was similar in both sexes. As in males, females have long
cylindrical smooth cuticular surface (Fig. 2, a). A cross section of the trunk in the
anterior middle section passes by the large lemniscus (L) (Fig. 2, a) and a thin sec-
tion of the sub-cuticular body wall layers that are greatly magnified in Fig. 2, b. In
that Figure (2, b) we observe the thin cuticle (C), the much thicker spongy hypoder-
mis (H) innervated by lacunar channels (LC) over laying the muscle layers (M). Note
Fig. 4. Ocular microscopy images of Neoechinorhynchus planilizai females collected from Planili-
za abu in the Tigris River, Iraq; a — a part of the male reproductive system emphasizing the
cement gland (CG) with at least 5 giant nuclei, the cement gland reservoir (CR), and the seminal
vesicle (SV); b — the posterior part of the male genital terminalia showing the posterior limb of
the seminal vesicle (SV), sperm (S), and the invaginated bursa (B; c — the complete female repro-
ductive system showing the vagina (V), swelling resembling a sphincter (S), short, thick-walled
and robust uterus (U), selective apparatus with a few cells (SA), and large pot-shaped uterine bell
(UB). The primary dorsal and ventral bundles of ligaments (DBL and VBL, respectively)
a
c
b
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that lacunar channels are smoothly drilled emulating blood vessels. Micropores were
observed on all anatomical structures. Note differences in size and distribution of
micropores in relation to the metabolic absorption of nutrients through the body
wall. Absorption rates clearly vary between the middle region of the trunk (Fig. 2, c)
compared to the posterior region (Fig. 2, d). Wright and Lumsden (1969, 1970) and
Byram and Fisher (1973) further reported that these are pores of peripheral canals
that are continuous, with canalicular crypts. These crypts appear to “constitute a
huge increase in external surface area implicated in nutrient up take”.Whitfield
(1979) estimated a 44-fold increase at a surface density of 15 invaginations per 1 μm2
of Moniliformis moniliformis (Bremser, 1811) Travassos 1915 tegumental surface
(Byram and Fisher, 1973). The egg of N. planilizai is fusiform-ellipsoid with a smooth
surface and apparent subcutaneous giant nuclei (Fig. 2, e) which is usually character-
istic of the early acanthella indicating that this acanthocephalan species is of preco-
cious nature. A forced break into eggs (Fig. 2, f) does not demonstrate any fibrils
which is not the case with the very similar N. iraqensis eggs, thus adding one more
distinguishing factor between the two species.
Anatomy of N. plani lizai us ing opt ica l microscopy
Thorough optical microscopic observations of the new specimens revealed many
features that have not been previously reported and are herein described for the
first time. Figures 3, a–4, c supplement the original description and overcome
the limitations of the 8-line drawings used there. The anterior trunk of a female
specimen (Fig. 3, a) shows the small size of the proboscis compared to the trunk,
the extensive size of the large lemniscus (L), the relatively large receptacle (PR)
with the triangulate cephalic ganglion, and a giant subcutaneous nucleus (GSN).
The darkly stained para-receptacle structure (PRS) can also be seen on the ven-
tral side of the receptacle. Only one ventral PRS is seen in each specimen. A
higher magnification of the anterior trunk (Fig. 3, b) shows more detail of the
anterior bulbous proboscis enclosing the darkly stained apical organ (arrow), the
proboscis receptacle (PR), triangulate cephalic ganglion (CG), and the PRS.
Parts of the subcutaneous giant nucleus (GSN) and a lemniscus (L) can also be
seen. Figure 3, c is comparable to Figure 3, d that emphasizes additional struc-
tures including the retractor muscles (RM), the girdle (G), and a new structure
that is herein named the receptacle papillae (RP) (arrow). The RP are paired
ovoid shaped structures that are somewhat constricted at junction with the re-
ceptacle and appear to have a branching internal framework. They are noted in
the original description (Fig. 2, C), but this structure is not mentioned or dis-
cussed. We do not know if the RP have any functional utility, but it certainly does
have a taxonomic value to distinguish N. planilizai from related species such as
N. iraqensis. A higher magnification of the proboscis receptacle (Fig. 3, d) em-
phasizes the cephalic ganglion (CG), retractor muscles (RM) and the PRS. Major
components of the male reproductive system include the testes a syncytial ce-
ment gland (CG), cement reservoir (CR) and ducts, seminal vesicle (CV) and
the bursa (Fig. 3, e). The anterior testis (AT) is invariably larger and longer than
the posterior testis (PT) and the cement gland includes up to 8 giant nuclei. Fig-
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ure 4, a gives a higher magnification of the cement gland (CG) showing at least
5 giant nuclei, the cement reservoir (CR) and the seminal vesicle (SV). A higher
magnification of the posterior end of the male terminalia (Fig. 4, b) showing the
posterior end of the seminal vesicle (SV) and Saefftigen’s pouch (S) also shows
the invaginated bursa (B) with sperm. A detail of the female reproductive system
(Fig. 4, c) demonstrates the angular vagina (V), swelling resembling sphincter
(S), short and robust uterus (U), prominent selective apparatus (SA) with a few
cells, and the large pot-shaped thick-walled uterine bell (UB) which is longer
than the rest of reproductive system. The primary dorsal and ventral bundles of
ligaments (DBL & VBL) are also prominent. All the above-mentioned structures
are specific and are herein described for the first time in N. planilizai, and hence,
have important taxonomic value.
Molecular results
The 18S dataset alignment includes sequences representing species of the ge-
nus Neoechinorhynchus, and Floridosentis. The 18S phylogenetic tree inferred
from ML and BI analyses shows that the sequences obtained in the present
study of N. planilizai are nested with other congeners with well supported boot-
strap and posterior probability support values (Fig. 5). In the clade I, N. planilizai
was placed as sister species of N. iraqensis from Iraq as the closest relative, while
the isolates of N. planilizai also revealed the clear inclusion of N. saginata
(KU363970) and N. crassus (KU363971, KU363974) both from Iran and Neo-
echinorhynchus sp. (MK507363) from China, along with Neoechinorhynchus sp.
(KU363972) from Iran respectively that appears to be most closely related
(Fig. 5). The 18S tree reconstruction portrayed clades I, II and III to accommo-
date Neoechinorhynchus species with good bootstrap and posterior probabilities
values (BS = 94; PP = 1.00) (Fig. 5). In both analyses, Neoechinorhynchus seemed
as paraphyletic, clustered in different main clades (Fig. 5). Clade I obtained in
this study is nested with species of Neoechinorhynchus (from Iran, Iraq, China,
Brazil and Vietnam) along with clade II that included the Neoechinorhynchus
species (from USA, Iran, and China that also comprises Floridosentis species
from Mexico (Fig. 5). The clade III formed by N. tumidus from Russia is in a
separate phylogenetic clade with well supported values (Fig. 5). Due to the mo-
lecular data constrained by the partial number of sequences and genetic mark-
ers employed for Neoechinorhynchus species from Iraq, the phylogenetic analy-
sis needs further revisions in the future. The status of the species of the ge-
nus Neoechinorhynchus required additional information from more representa-
tive members of the class Eoacanthocephala (Ru et al., 2022). The present spe-
cies belongs to clade I and the data related to the species (Clade I, II and III)
shows in the table (Table 2). The clade I consists of species N. planilizai from
present study from Iraq shows the genetic divergence with N. iraqensis (from
Iraq), N. crassus, N. saginata and Neoechinorhynchus sp. (KU363972), all from
Iran and Neoechinorhynchus sp. (MK507363) from China showing the genetic
divergence ranging from 4.2 to 8.2%, while only the Iraqi species N. iraqensis
shows a genetic divergence of 4.2%.
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Table 2 . Acanthocephala species, GenBank accession numbers, origin
and source used for phylogenetic analysis based on the 18S region.
Asterisk* shows data available as unpublished and species sequenced
during this study are shown in bold
Species GenBank
accession no. Location Reference
Neoechinorhynchus personatus MN149067 Spain Sarabeev et al., 2020
Neoechinorhynchus personatus MN149068,
MN149069,
MN149070
Ukraine Sarabeev et al., 2020
Neoechinorhynchus personatus MT020794,
MT020795
Tunisia Amin et al., 2020
Neoechinorhynchus agilis MN148895,
MN148896,
MN148897,
MN148898
Spain Sarabeev et al., 2020
Neoechinorhynchus yamagutii MN149220 Russia Sarabeev et al., 2020
Neoechinorhynchus sp. JYW-2010 HM545898 China Wang et al., 2010 *
Neoechinorhynchus aldrichettae OM103593,
OM103594,
OM103595
Austra-
lia
Huston et al., 2022
Neoechinorhynchus dimorphospinus MK510080 Thailand Amin et al., 2019 b
Neoechinorhynchus cephali MN992024 India Kaur et al., 2020 *
Neoechinorhynchus johnii MK260005,
MK260007
Vietnam Amin et al., 2019 a
Neoechinorhynchus pseudemydis KU363973 Iran Dadar and Adel, 2016 *
Neoechinorhynchus pseudemydis U41400 USA Near and Nadler, 1996 *
Neoechinorhynchus qinghaiensis MW144440 China Pan, 2020*
Neoechinorhynchus crassus AF001842 USA Near et al., 1998
Neoechinorhynchus crassus KU363969 Iran Dadar and Adel, 2016 *
Neoechinorhynchus tumidus KF156876 Russia Malyarchuk et al., 2014
Neoechinorhynchus cylindratus MF974925 USA Blubaugh and Gauthier, 2018 *
Neoechinorhynchus saginata AY830150 USA Garcia-Varela and Nadler, 2005
Neoechinorhynchus buttnerae MK249749 Brazil Souza and Benavides, 2018 *
Neoechinorhynchus buttnerae MW590330 Brazil Soares et al., 2021 *
Neoechinorhynchus sp. KM507363 China Liu et al., 2014 *
Neoechinorhynchus sp. KU363972 Iran Adel and Dadar, 2016 *
Neoechinorhynchus saginata KU363970 Iran Dadar and Adel, 2016 *
Neoechinorhynchus crassus KU363971 Iran Dadar and Adel, 2016 *
Neoechinorhynchus crassus KU363974 Iran Dadar and Adel, 2016 *
Neoechinorhynchus planilizai PX506235,
PX506229
Iraq Present study
Neoechinorhynchus iraqensis PV776638,
PV776640
Iraq Amin et al., 2026
Floridosentis pacifica MT527841 Mexico Rosas-Valdez et al., 2020
Floridosentis mugilis AF064811 Mexico García-Varela et al., 2000
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Discussion
In the present study, N. planilizai was identified based on integrated approach, use of
morphology and molecular data. Initial differential diagnosis of freshly collected ma-
terials was challenging as specimens of this species are often readily confused with the
very similar species N. iraqensis which is also collected from the same host species
P. abu in the same waters (Table 1). Worms of both species are similarly long, cylindri-
cal, cord-like, smooth and with similar proboscides. To pick specimens for research
purposes, we can only distinguish the two species apart under a dissecting scope
against a back-light source when we can find the para-receptacle structure which is
found only in N. planilizai and not in N. iraqensis. Subsequent microscopic examina-
tion brings about more anatomical differences such as the pot-shaped uterine bell and
the dorsal and ventral ligament bundles in N. planilizai compared to the egg fibrils and
the beady lining on the inner body wall in N. iraqensis, among other differences.
The present study thus advances our knowledge of the diversity of Neoechinorhy-
nchus species in West Asia, high-lightening the requirement for keen studies on this
group of parasites. Despite the many reports on fish parasites from various Arabian
Gulf waterways, ex., Mhaisen (2002) and Mhaisen and Abdul-Ameer (2024), includ-
ing a few descriptions, none has been so thoroughly studied like N. iraqensis. Never-
theless, our study of a good collection of new specimens, demonstrated that the origi-
nal description of N. planilizai did not cover most facets of its morphology and anato-
my. This presentation completes its morphological description using ocular microsco-
py and SEM images for the first time with special references to proboscis hooks, ante-
rior trunk landscape, micropores, para-receptacle structure, lemnisci, reproductive
structures topography, and egg anatomy. In the original description, Al-Ayash et al.
(2021) mention that “Trunk end (genital terminalia) like round bulb, with big rounded
or ovoid sensory papillae.” We believe that their “sensory papillae” were misidentified
and their Fig. 2, E clearly mislabeled the invaginated bursa and their external “bsp”
(bursa sensory papillae).
Our study also adds a molecular confirmation of its identity using the 18S gene.
(Fig. 5). Molecular analyses of new acanthocephalan taxa, especially of the genus Neo-
echinorhynchus Stiles and Hassall, 1905 have not been used in the Arabian Gulf region
in the past except very recently study on N. iraqensis (Amin et al., 2026). We hope that
we are introducing a trend of new taxonomic research of the acanthocephalans of fish-
es in this important region of the Middle East. Within acanthocephalans, Neoechino-
rhynchus is the most diverse genus with about 117 species described already and they
are distributed globally (Amin, 2013; Smales, 2013; Pinacho-Pinacho et al., 2014). De-
spite that, with regard to the molecular data, and compared to the species already de-
scribed, there is still a gap in molecular studies that needs to be filled. Molecular data
from other congeneric species of Neoechinorhynchus need to be generated in order to
understand their phylogenetic relationships, which will provide a more comprehensive
view of the genus. The previous studies of the genus Neoechinorhynchus using molecular
data, predicted that the genus is paraphyletic (Pinacho-Pinacho et al., 2018), with
which we are also agree and it is coherent with present study.
The species examined in the present study as N. planilizai from Tigris River,
Iraq were nested within clade I that encompasses most of the fish acanthoceph-
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Fig. 5. Phylogenetic relationship among acanthocephalans based on the Maximum Likelihood
(ML) and Bayesian Inference (BI) analysis of 18S rDNA gene sequences. Bootstrap values and
Posterior probabilities on nodes are shown as maximum likelihood/Bayesian inference. The new
sequences generated in this study are in blue. The species mentioned in red belongs to Planiliza
abu (as same host as Neoechinorhynchus planilizai) from the Euphrates River, Iraq. The GenBank
accession numbers are provided before the species names and the scale bars indicates substitu-
tions per site. Unsupported nodes by BI are marked with a hyphen
alans. Clade I comprised species analyzed from the Middle East (Neoechinorhyn-
chus iraqensis, N. pseudemydis, N. crassus, Neoechinorhynchus sp. GL-2015 and
N. saginata) including the present species. The present study’s phylogenetic analy-
ses concluded with the 18S gene sequences established the presently studied species
N. planilizai within congeners. The interspecific genetic divergence estimated on
the present study between the isolates of N. planilizai with Middle East species in
clade I ranged from 4.2 to 8.2%. Furthermore, the phylogenetic trees inferred with
the 18S dataset reliably designate that the genus Neoechinorhynchus is not mono-
phyletic. Although, in regard to Neoechinorhynchus status, polyphyletic or paraphy-
letic, it still remains an open question. Previous studies support its status as poly-
phyletic (Ru et al., 2022; Sereno-Uribe et al., 2022), while in another study, Neoechi-
norhynchus was suggested to be paraphyletic (Pinacho-Pinacho et al., 2017). How-
ever, Barger (2004) and Barger & Nickol (2004) demonstrated that Neoechinorhyn-
chus associated with emydid turtles formed a monophyletic assemblage as did Near
Redescription and Molecular Analysis of Neoechinorhynchus (Neoechinorhynchus)
ISSN 2707-725X. Zoodiversity. 2026. Vol. 60, No. 4
419
& Nadler (1996 in an un-sourced paper). Our phylogenetic results are consistent
with the studies of Malyarchuk et al. (2014), Pinacho-Pinacho et al. (2017), Amin et
al. (2019 b), and Kaur & Sanil (2021).
In summary, further study of the distribution of Neoechinorhynchus spp. in dif-
ferent Middle East countries necessitates the collection of additional molecular data
for a more comprehensive study. The availability of sequence data would lead to a
better understanding of their phylogenetic relationships, and to clarify the species
systematic positions.
Acknowledgements. This project was supported by an Institutional Grant from
the Parasitology Center, Inc. (PCI), Scottsdale, Arizona. The authors thank the Head,
Department of Zoology, Chaudhary Charan Singh University, Meerut, India. The
authors also express their gratitude to Centro Multiusuário para Análises de
Fenômenos Biomédicos, Universidade do Estado do Amazonas for the technical
support, Laboratório de Helmintologia Romero Lascasas Porto, Universidade do Es-
tado do Rio de Janeiro for the technical support, and Fundação Carlos Chagas Filho
de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) for the postdoctoral
grant under number E-26/204.620/2024. AHA and MHA thank the Department of
Fisheries and Marine Resources, University of Basrah, for supporting the project as
part of a Ph. D. study. We thank Prof. Furhan T. Mhaisen from Tegnervägen, Ka-
trineholm, Sweden for providing AHA by all previous records of endoparasites of
Tigris catfish Silurus triostegus from Iraq from his unpublished book “Index-cata-
logue of parasites and disease agents of fishes of Iraq”.
Authors contribution. Omar Amin did the research, confirmed species validity,
wrote the manuscript, and created the optical microscopy images. Anshu Chaud-
hary did and wrote the molecular part and critically revised the manuscript. Makoto
Enoki Caracciolo carried out the processing and execution of the SEM analysis. Ath-
eer Ali and Mohammed Al-Kuraizy proposed the revision and provided research
specimens. Nataliya Rubtsova refined and organized all images. Wanderley de Souza
provided the SEM microscopy laboratory facilities and scientific support. Singh pro-
vided molecular lab facilities in India. All authors reviewed the manuscript and rec-
ommended submission.
Conflict of Interest. The authors declare no conflicts of interest.
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Received 9 July 2026
Accepted 12 August 2026
|
| id | oai:ojs.akademperiodyka.org.ua:article-1018 |
| institution | Zoodiversity |
| issn | 2707-7268 |
| keywords_txt_mv | |
| language | English |
| last_indexed | 2026-08-27T01:00:42Z |
| publishDate | 2026 |
| publisher | Publishing House "Akademperiodyka" of the National Academy of Sciences of Ukraine |
| record_format | ojs |
| resource_txt_mv | ojsakademperiodykaorgua/bb/801ab10a6ab4f713ce9c851285127ebb.pdf |
| spelling | oai:ojs.akademperiodyka.org.ua:article-10182026-08-26T09:51:17Z Redescription and molecular analysis of Neoechinorhynchus (Neoechinorhynchus) planilizai (Acanthocephala, Neoechinorhynchidae) from Planiliza abu (Mugilidae) in Iraq Amin, O. M. Chaudhary , A. Caracciolo , M. E. Ali , A. H. Al-Kuraizy , M. H. Rubtsova, N. Y. Singh , H. S. scanning electron microscopy 18S rDNA phylogenetic relationships para-receptacle structure Tigris River fish parasites Neoechinorhynchus (N.) planilizai Al-Ayash, Gustinelli, Al-Nasiri, Caffara, 2021 was recently described from Planiliza abu (Heckel) in Iraq using line drawings. We update and complete that description using new ocular microscopy, SEM, and molecular analysis. New collections revealed structures that have not been previously reported including constricted proboscis, posterior hooks longer than middle hooks, bursa without sensory structures, spongy hypodermic tissue with lacunar channels under smooth cuticular surface, eggs with no fibrils, variable micropores, single ventral para-receptacle structure, large triangulate cephalic ganglion, a new papilla at the posterior tip of the proboscis receptacle, an anterior testis distinctly longer than posterior testis, short robust uterus a huge pot-shaped uterine bell, and two sets of ligament bundles emerging from the inner posterior tip of the trunk. No other taxonomic accounts of this species are known. The molecular analysis of N. planilizai is also described with sequences of the 18S nuclear ribosome generated and aligned with closely related sequences from GenBank database. Maximum likelihood and Bayesian inference analyses demonstrated that N. (N) planilizai was nested within neoechinorhynchid clades. Th e presence of N. (N) planilizai with other Middle East species in the tree allowed its characterization for the first time using morphological and molecular features. Publishing House "Akademperiodyka" of the National Academy of Sciences of Ukraine 2026-07-09 Article Article application/pdf https://ojs.akademperiodyka.org.ua/index.php/Zoodiversity/article/view/1018 10.15407/zoo2026.04.405 Zoodiversity; Vol. 60 No. 4 (2026): Zoodiversity Zoodiversity (Vestnik Zoologii); Том 60 № 4 (2026): Zoodiversity 2707-7268 2707-725X 10.15407/zoo2026.04 en https://ojs.akademperiodyka.org.ua/index.php/Zoodiversity/article/view/1018/410 Copyright (c) 2026 O. M. Amin, A. Chaudhary , M. E. Caracciolo , A. H. Ali , M. H. Al-Kuraizy , N. Y. Rubtsova, H. S. Singh |
| spellingShingle | Amin, O. M. Chaudhary , A. Caracciolo , M. E. Ali , A. H. Al-Kuraizy , M. H. Rubtsova, N. Y. Singh , H. S. Redescription and molecular analysis of Neoechinorhynchus (Neoechinorhynchus) planilizai (Acanthocephala, Neoechinorhynchidae) from Planiliza abu (Mugilidae) in Iraq |
| title | Redescription and molecular analysis of Neoechinorhynchus (Neoechinorhynchus) planilizai (Acanthocephala, Neoechinorhynchidae) from Planiliza abu (Mugilidae) in Iraq |
| title_full | Redescription and molecular analysis of Neoechinorhynchus (Neoechinorhynchus) planilizai (Acanthocephala, Neoechinorhynchidae) from Planiliza abu (Mugilidae) in Iraq |
| title_fullStr | Redescription and molecular analysis of Neoechinorhynchus (Neoechinorhynchus) planilizai (Acanthocephala, Neoechinorhynchidae) from Planiliza abu (Mugilidae) in Iraq |
| title_full_unstemmed | Redescription and molecular analysis of Neoechinorhynchus (Neoechinorhynchus) planilizai (Acanthocephala, Neoechinorhynchidae) from Planiliza abu (Mugilidae) in Iraq |
| title_short | Redescription and molecular analysis of Neoechinorhynchus (Neoechinorhynchus) planilizai (Acanthocephala, Neoechinorhynchidae) from Planiliza abu (Mugilidae) in Iraq |
| title_sort | redescription and molecular analysis of neoechinorhynchus (neoechinorhynchus) planilizai (acanthocephala, neoechinorhynchidae) from planiliza abu (mugilidae) in iraq |
| topic_facet | scanning electron microscopy 18S rDNA phylogenetic relationships para-receptacle structure Tigris River fish parasites |
| url | https://ojs.akademperiodyka.org.ua/index.php/Zoodiversity/article/view/1018 |
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