The caryophyllidean tapeworm Khawia armeniaca has long been regarded as an exceptionally widespread species within its genus, notable for its significant morphological variability. However, with the accumulation of molecular data from different fish hosts, K. armeniaca was suspected to represent a species complex. To clarify the true identity of these parasites, a comprehensive morphological and molecular study (using 18S, 28S and ITS2 ribosomal regions) of K. armeniaca tapeworms from barbels (Barbinae) across the Iberian Peninsula and the Middle East has been conducted. The results revealed two genetically distinct lineages within the K. armeniaca complex. The first lineage, found in Arabibarbus grypus, Barbus lacerta, Capoeta birunii, Carassobarbus luteus, Luciobarbus barbulus, L. esocinus and L. kersin in Iraq and Iran, is genetically congruent with K. armeniaca (Cholodkovsky, 1915), originally described from the Sevan khramulya (Capoeta sevangi) in Armenia. The second lineage, identified in Luciobarbus bocagei (type host), L. comizo and L. guiraonis from Portugal and Spain, is described as Khawia iberica n. sp. In addition to clear molecular divergence, K. iberica can be distinguished from K. armeniaca by notable morphological differences, including variations in the shape, structure and size of the ovary, the anterior extension of the vitelline follicles, the testes and several morphometric parameters.

Department of Botany and Zoology Faculty of Science Masaryk University Brno Czech Republic

Department of Zoology Faculty of Natural Sciences Comenius University in Bratislava Bratislava Slovakia

Institute of Parasitology Biology Centre Czech Academy of Sciences České Budějovice Czech Republic

See more in PubMed

Abderrafik M, Khedidja MB, Amel BTN, Eddine ZD, and Smail M (2010) Microscopie électronique à balayage des parasites des poissons du lac Oubeira-Algérie.

Al-Kalak SN, and Rahemo ZIF (2003) Morphological and histological studies on

Barčák D, Oros M, Hanzelová V and Scholz T (2017) A synoptic review of PubMed

Bazsalovicsová E, Králová-Hromadová I, Brabec J, Hanzelová V, Oros M and Scholz T (2014) Conflict between morphology and molecular data: A case of the genus PubMed

Casal-López M and Doadrio I (2018) The Messinian imprint on the evolution of freshwater fishes of the genus

Cordero del Campillo M, Castañon L, and Reguera A (1994)

Dinnik JA (1933) [Les vers parasitiques des poissons du lac de Sevan].

Doadrio I (1990) Phylogenetic relationships and classification of western Palaearctic species of the genus

Froese R and Pauly D (2025)

Gante HF, Doadrio I, Alves MJ and Dowling TE (2015) Semi-permeable species boundaries in Iberian barbels ( PubMed PMC

Chervy L (2024) Laboratory techniques for the systematic and phylogenetic study of tapeworms (Cestoda) parasitic in bony fishes, amphibians and reptiles. PubMed

Cholodkovsky N (1915) Notes helminthologiques.

Choudhury A and Scholz T (2020) PubMed

Chubb J, Eiras JC and Saraiva A (1997)

International Commission on Zoological Nomenclature (2012) Amendment of articles 8, 9, 10, 21 and 78 of the international code of zoological nomenclature to expand and refine methods of publication. PubMed DOI PMC

Katoh K, Misawa K, Kuma KI and Miyata T (2002) MAFFT: A novel method for rapid multiple sequence alignment based on fast Fourier transform. PubMed PMC

Kibet C, Wen-Ting Z, Huda S and Pin N (2021) Redescription of the monozoic cestode

Kottelat M and Freyhof J (2007) In

Kuchta R, Řehulková E, Francová K, Scholz T, Morand S and Šimková A (2020) Diversity of monogeneans and tapeworms in cypriniform fishes across two continents. PubMed

Kulakovskaya OP (1961) [Materials on the fauna of Caryophyllaeidae (Cestoda, Pseudophyllidea) of the Soviet Union.]

Lanave C, Preparata G, Saccone C and Serio G (1984) A new method for calculating evolutionary substitution rates. PubMed

Levin BA, Freyhof J, Lajbner Z, Perea S, Abdoli A, Gaffaroğlu M, Özuluğ M, Rubenyan HR, Salnikov VB and Doadrio I (2012) Phylogenetic relationships of the algae scraping cyprinid genus PubMed

Mackiewicz JS (1972) Caryophyllidea (Cestoidea): A review. PubMed

Mackiewicz JS (1994) Order Caryophyllidea van Beneden in Carus, 1863. In Khalil LF, Jones A and Bray RA (eds.),

Mackiewicz JS (2003) Caryophyllidea (Cestoidea): Molecules, morphology and evolution.

Machordom A and Doadrio I (2001) Evidence of a Cenozoic Betic-Kabilian connection based on freshwater fish phylogeography ( PubMed

Mikailov TK (1975) [Parasites of fish in the reservoirs of Azerbaydzhan (systematics, dynamics and origin).]

Nadler SA, and Pérez-Ponce de León G (2011) Integrating molecular and morphological approaches for characterizing parasite cryptic species: Implications for parasitology. PubMed

Oellermann LK and Skelton PH (1990) Hexaploidy in yellowfish species (

Oros M, Scholz T, Hanzelová V and Mackiewicz JS (2010) Scolex morphology of monozoic cestodes (Caryophyllidea) from the Palaearctic Region: A useful tool for species identification. PubMed

Oros M, Uhrovič D, Choudhury A, Mackiewicz JS and Scholz T (2020) Scolex morphology of monozoic tapeworms (Caryophyllidea) from the Nearctic Region: Taxonomic and evolutionary implications. PubMed

Özdemir Y, and Sarıeyyüpoğlu M (1993) Some parasites of

Paperna I (1964) The metazoan parasite fauna of Israel inland water fishes.

Perea S, Böhme M, Zupančič P, Freyhof J, Šanda R, Özuluğ M, Abdoli A and Doadrio I (2010) Phylogenetic relationships and biogeographical patterns in circum Mediterranean subfamily Leuciscinae (Teleostei, Cyprinidae) inferred from both mitochondrial and nuclear data. PubMed PMC

Popov TA (1924) [The anatomical structure of

Protasova EP, Kuperman BI, Roitman VA, and Poddubnaya LG (1990) [

Rahemo ZIF and Al-Kalak SN (1993) A new record of a caryophyllaeid cestode,

Rahemo ZIF, and Mohammad SA (2002)

Rambaut A, Drummond AJ, Xie D, Baele G and Suchard MA (2018) Posterior summarization in Bayesian phylogenetics using Tracer 1.7. PubMed PMC

R Core Team (2022)

Ronquist F, Teslenko M, van der Mark P, Ayres DL, Darling A, Höhna S, Larget B, Liu L, Suchard MA and Huelsenbeck JP (2012) MrBayes 3.2: Efficient Bayesian phylogenetic inference and model choice across large model space. PubMed PMC

Shulman SS (1958) [Zoogeographical analysis of parasites of freshwater fish of the USSR.] Basic Problems of the Parasitology of Fish. Leningrad: Izdatelstvo Leningradskogo Universiteta, 184–230. (In Russian)

Scholz T, Brabec J, Kráľová-Hromadová I, Oros M, Bazsalovicsová E, Ermolenko A and Hanzelová V (2011) Revision of PubMed

Scholz T, and Kuchta R (2017) A digest of fish tapeworms.

Scholz T, and Oros M (2017)

Scholz T, Oros M, Bazsalovicsová E, Brabec J, Waeschenbach A, Xi B-W, Aydoğdu A, Besprozvannykh V, Shimazu T, Králová-Hromadová I and Littlewood DTJ (2014) Molecular evidence of cryptic diversity in PubMed

Scholz T, Waeschenbach A, Oros M, Brabec J and Littlewood DTJ (2021) Phylogenetic reconstruction of early diverging tapeworms (Cestoda: Caryophyllidea) reveals ancient radiations in vertebrate hosts and biogeographic regions. PubMed

Stamatakis A (2006) RAxML-VI-HPC: Maximum likelihood-based phylogenetic analyses with thousands of taxa and mixed models. PubMed

Stamatakis A (2014) RAxML version 8: A tool for phylogenetic analyses and postanalysis of large phylogenies. PubMed PMC

Tang Q, Getahun A and Liu H (2009) Multiple in-to-Africa dispersals of labeonin fishes (Teleostei: Cyprinidae) revealed by molecular phylogenetic analysis.

Tsigenopoulos CS, Durand JD, Unlu E and Berrebi P (2003) Rapid radiation of the Mediterranean

Tsigenopoulos CS, Kasapidis P and Berrebi P (2010) Phylogenetic relationships of hexaploid large-sized barbs (genus PubMed

Waeschenbach A, Webster BL and Littlewood DTJ (2012) Adding resolution to ordinal level relationships of tapeworms (Platyhelminthes: Cestoda) with large fragments of mtDNA. PubMed

Williams JS, Gibson DI and Sadighian A (1980) Some helminth parasites of Iranian freshwater fishes.

Xi B, Oros M, Wang G, Scholz T and Xie J (2013) PubMed

Yang L, and Mayden RL (2010) Phylogenetic relationships, subdivision, and biogeography of the cyprinid tribe Labeonini ( PubMed

Yang L, Sado T, Hirt MV, Pasco-Viel E, Arunachalam M, Li J, Wang X, Freyhof J, Saitoh K, Simons AM, Miya M, He S and Mayden RL (2015) Phylogeny and polyploidy: Resolving the classification of cyprinine fishes (Teleostei: Cypriniformes). PubMed

Zareian H, Esmaeili HR, Gholamhosseini A, Japoshvili B, Özuluğ M and Mayden RL (2018) Diversity, mitochondrial phylogeny, and ichthyogeography of the