Uncovering the monogenean species diversity of cyprinoid fish in Iraq using an integrative approach.

The freshwaters of Iraq harbour a high diversity of endemic and phylogenetically unique species. One of the most diversified fish groups in this region is cyprinoids, and although their distribution is relatively well known, their monogenean parasites have only rarely been investigated. Herein, we applied an integrative approach, combining morphology with molecular data, to assess the diversity and phylogeny of cyprinoid-associated monogenean parasites. A total of 33 monogenean species were collected and identified from 13 endemic cyprinoid species. The highest species diversity was recorded for Dactylogyrus (Dactylogyridae, 16 species) and Gyrodactylus (Gyrodactylidae, 12 species). Four species of Dactylogyrus and 12 species of Gyrodactylus were identified as new to science and described. Two other genera, Dogielius (Dactylogyridae) and Paradiplozoon (Diplozoidae), were represented only by 4 and 1 species, respectively. Phylogenetic analyses of the Dactylogyrus and Gyrodactylus species revealed that the local congeners do not form a monophyletic group and are phylogenetically closely related to species from other regions (i.e. Europe, North Africa and Eastern Asia). These findings support the assumption that the Middle East served as an important historical crossroads for the interchange of fauna between these 3 geographic regions.

Monogeneans and chubs: Ancient host-parasite system under the looking glass.

Host-parasite coevolution is one of the fundamentals of evolutionary biology. Due to the intertwined evolutionary history of two interacting species and reciprocal coadaptation processes of hosts and parasites, we can expect that studying parasites will shed more light onto the evolutionary processes of their hosts. Monogenea (ectoparasitic Platyhelminthes) and their cyprinoid fish hosts represent one of the best models for studying host-parasite evolutionary relationships using a cophylogenetic approach. These parasites have developed remarkably high host specificity, where each host species often serves as a potential host for its own host-specific monogenean species. Here, the cophylogenetic relationships in the Dactylogyrus-Squalius system was investigated, as Squalius is one of several cyprinoid genera with puzzling phylogeography and inhabits all four major peri-Mediterranean peninsulas. Of 29 endemic Squalius species examined for the presence of Dactylogyrus parasites, a total of 13 Dactylogyrus species were collected from the gills of 20 Squalius species across a wide range of distribution. Phylogenetic reconstruction revealed a polyphyletic origin for Dactylogyrus species parasitizing congeneric Squalius, with four major clades being recognized. On the basis of the delimitation of host specificity, strict specialists parasitizing single host species, geographic specialists parasitizing congeners in a limited geographical region, and true generalists parasitizing congeners in various geographical regions were recognized in Dactylogyrus species parasitizing Squalius. The phylogenetic reconstruction of Squalius hosts revealed two major clades, the first encompassing only peri-Mediterranean species and the second including species from other Euro-Asian regions. Distance-based cophylogenetic methods did not reveal a statistically significant global cophylogenetic structure in the studied system; however, several host-parasite links among Iberian endemic species contributed significantly to the overall structure. The widest host range and associated genetic variability were recorded for D. folkmanovae, parasitizing nine Squalius species, and D. vistulae, parasitizing 13 Squalius species. Two different dispersion mechanisms and morphological adaptations to Squalius hosts were clearly reflected in the contrasting cophylogenetic patterns for these two species with different levels of host specificity. While host-parasite cospeciation plays an important role in diversification within D. folkmanovae, diversification within D. vistulae is driven mainly by host switching.

The First Record of the Invasive Asian Fish Tapeworm (Schyzocotyle Acheilognathi) from An Endemic Cichlid Fish in Madagascar.

The Asian fish tapeworm, Schyzocotyle acheilognathi (Yamaguti, 1934) (Cestoda: Bothriocephalidea), is an invasive parasite of freshwater fishes that have been reported from more than 200 freshwater fish worldwide. It was originally described from a small cyprinid, Acheilognathus rombeus, in Japan but then has spread, usually with carp, minnows or guppies, to all continents including isolated islands such as Hawaii, Puerto Rico, Cuba or Sri Lanka. In the present account, we report the first case of the infection of a native cichlid fish, Ptychochromis cf. inornatus (Perciformes: Cichlidae), endemic to Madagascar, with S. acheilognathi. The way of introduction of this parasite to the island, which is one of the world's biodiversity hotspots, is briefly discussed.

Metazoan parasite communities: support for the biological invasion of Barbus barbus and its hybridization with the endemic Barbus meridionalis.

BACKGROUND: Recently, human intervention enabled the introduction of Barbus barbus from the Rhône River basin into the Barbus meridionalis habitats of the Argens River. After an introduction event, parasite loss and lower infection can be expected in non-native hosts in contrast to native species. Still, native species might be endangered by hybridization with the incomer and the introduction of novel parasite species. In our study, we aimed to examine metazoan parasite communities in Barbus spp. populations in France, with a special emphasis on the potential threat posed by the introduction of novel parasite species by invasive B. barbus to local B. meridionalis. METHODS: Metazoan parasite communities were examined in B. barbus, B. meridionalis and their hybrids in three river basins in France. Microsatellites were used for the species identification of individual fish. Parasite abundance, prevalence, and species richness were compared. Effects of different factors on parasite infection levels and species richness were tested using GLM. RESULTS: Metazoan parasites followed the expansion range of B. barbus and confirmed its introduction into the Argens River. Here, the significantly lower parasite number and lower levels of infection found in B. barbus in contrast to B. barbus from the Rhône River supports the enemy release hypothesis. Barbus barbus × B. meridionalis hybridization in the Argens River basin was confirmed using both microsatellites and metazoan parasites, as hybrids were infected by parasites of both parental taxa. Trend towards higher parasite diversity in hybrids when compared to parental taxa, and similarity between parasite communities from the Barbus hybrid zone suggest that hybrids might represent "bridges" for parasite infection between B. barbus and B. meridionalis. Risk of parasite transmission from less parasitized B. barbus to more parasitized B. meridionalis indicated from our study in the Argens River might be enhanced in time as higher infection levels in B. barbus from the Rhône River were revealed. Hybrid susceptibility to metazoan parasites varied among the populations and is probably driven by host-parasite interactions and environmental forces. CONCLUSIONS: Scientific attention should be paid to the threatened status of the endemic B. meridionalis, which is endangered by hybridization with the invasive B. barbus, i.e. by genetic introgression and parasite transmission.

Permanent genetic resources added to molecular ecology resources database 1 April 2013-31 May 2013.

This article documents the addition of 234 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Acipenser sinensis, Aleochara bilineata, Aleochara bipustulata, Barbus meridionalis, Colossoma macropomum, Delia radicum, Drosophila nigrosparsa, Fontainea picrosperma, Helianthemum cinereum, Liomys pictus, Megabalanus azoricus, Pelteobagrus vachelli, Pleuragramma antarcticum, Podarcis hispanica type 1A, Sardinella brasiliensis and Sclerotinia homoeocarpa. These loci were cross-tested on the following species: Acipenser dabryanus, Barbus balcanicus, Barbus barbus, Barbus cyclolepis, Drosophila hydei, Drosophila melanogaster, Drosophila obscura, Drosophila subobscura, Fontainea australis, Fontainea fugax, Fontainea oraria, Fontainea rostrata, Fontainea venosa, Podarcis bocagei, Podarcis carbonelli, Podarcis liolepis, Podarcis muralis and Podarcis vaucheri.

[Impact of aortic stiffness on central hemodynamics and cardiovascular system]. / Vplyv tuhosti aorty na centrálnu hemodynamiku a na kardiovaskulárny systém.

Arterial stiffness increases as a result of degenerative processes accelerated by aging and many risk factors, namely arterial hypertension. Basic clinical examination reveals increased pulse pressure as its hemodynamic manifestation. The most serious consequence of increased vascular stiffness, which cannot be revealed by clinical examination, is a change of central hemodynamics leading to increased load of left ventricle, left ventricular hypertrophy, diastolic dysfunction and to overall increase of cardiovascular risk. This review aimed to point at some patophysiological mechanisms taking part in the development of vascular stiffness, vascular remodeling and hemodynamic consequences of these changes. This work also gives an overview of noninvasive examination methods and their characteristics enabling to evaluate the local, regional and systemic arterial stiffness and central pulse wave analysis and their meaning for central hemodynamics and heart workload.

Metabolic syndrome and its effect on aortic stiffness in premenopausal women.

BACKGROUND: Metabolic syndrome (MS) is a cluster of proatherogenic risk factors (RF) (abdominal obesity, atherogenic dyslipidemia, impaired fasting glucose or type 2 diabetes mellitus, higher blood pressure or antihypertensive therapy) that move patients into a higher risk for development of cardiovascular disease (CVD) and type 2 diabetes. The preclinical (subclinical) target organ diseases (SOD) are early signs of atherosclerosis. An increased aortic stiffness characterised by an increased pulse wave velocity in aorta (PWV Ao) is one of SOD.The aim of the present study was to assess the impact of metabolic syndrome (MS) on aortic wall stiffness and the risk profile in premenopausal women. METHODS: The aortic stiffness was measured using Arteriograph-Tensiomed, based on oscillometric measurement and analysis of the shape of brachial pulse wave, giving the PWV Ao. The results of measurements characterise a global aortic stiffness. RESULTS: We examined 81 premenopausal women (without history of CVD). The MS (according to the 2009 "harmonizing" definition) was present in 31 women (mean age 41.5 y), in the control group, there were 50 women (39 y). The most frequent components of MS were abdominal obesity (93 % vs 42%), arterial hypertension (68 % vs 10 %) and dyslipidemia (29 % vs 8 %). The PWV Ao was significantly higher in women with MS (9.26 m/s) compared to the control group (7.44 m/s). CONCLUSION: The aortic stiffness in women with MS compared to controls was significantly higher despite a presumed general protective hormonal effect on cardiovascular system in women with child-bearing potential (Tab. 4, Ref. 25).

Parasite diversity and microsatellite variability in native and introduced populations of four Neogobius species (Gobiidae).

Species introduced into new areas often show a reduction in parasite and genetic diversity associated to the limited number of founding individuals. In this study, we compared microsatellite and parasite diversity in both native (lower Danube) and introduced populations of 4 Ponto-Caspian gobies, including those (1) introduced from within the same river system (middle Danube; Neogobius kessleri and N. melanostomus), and (2) introduced from a different river system (River Vistula; N. fluviatilis and N. gymnotrachelus). Microsatellite data confirmed the lower Danube as a source population for gobies introduced into the middle Danube. Both native and introduced (same river system) populations of N. kessleri and N. melanostomus had comparable parasite species richness and microsatellite diversity, possibly due to multiple and/or continual migration/introduction of new individuals and the acquisition of local parasites. Reduced parasite species richness and microsatellite diversity were observed in introduced (different river system) populations in the Vistula. A low number of colonists found for N. fluviatilis and N. gymnotrachelus in the Vistula potentially resulted in reduced introduction of parasite species. Insufficient adaptation of the introduced host to local parasite fauna, together with introduction into an historically different drainage system, may also have contributed to the reduced parasite fauna.

From preoperative to intraoperative detection of hyperfunctioning parathyroid glands using tetrofosmin (99mTc) in primary hyperparathyroidism.

The impact of preoperative scintigraphy on the management of patients with primary hyperparathyroidism has been largely documented for more than two decades. More recently, preoperative scintigraphy has also been used to select patients for intraoperative detection of hyperfunctioning parathyroid glands thanks to a gamma-probe. This procedure is now widely used, with MIBI as the main radiopharmaceutical for both preoperative scintigraphy and intraoperative detection. However MIBI was not available in Slovakia until very recently and tetrofosmin (TF), the alternative 99mTc labelled radiopharmaceutical for myocardial imaging has some advantages over MIBI and a close biological behaviour. Thus we have been using TF also for parathyroid preoperative scintigraphy and for intraoperative detection, a systematic indication which has never been reported by others. This article aims to demonstrate the feasibility and to present our protocol for TF parathyroid imaging and intraoperative detection, closely associating surgeons, nuclear medicine specialists, pathologists and also biologists as intraoperative assay of intact PTH is necessary. The results of literature are subsequently reported and discussed (Tab. 2, Fig. 4, Ref. 35). Full Text in free PDF www.bmj.sk.

The epidermal structure of Carassius gibelio: a link with ploidy status in spawning and postspawning periods.

A reduction of epidermal club cells and an increase of goblet cells were found in Carassius gibelio during spawning when compared to postspawning. A significantly lower proportion of club cells at spawning was found in diploid males and triploid females than in diploid females. It could be linked to male efforts to avoid a fright reaction and the potential adoption of this strategy by gynogenetic females, or alternatively to a higher parasite infection or immunosuppression during spawning.

[Metabolic syndrome and aortic stiffness]. / Metabolický syndróm a tuhost' aorty.

INTRODUCTION: The metabolic syndrome (MS) is a cluster of risk factors that move the patient into higher level of risk category of cardiovascular disease and the probability of type 2 diabetes mellitus manifestation. Definition of MS is s based on the presence of selected risk factors as: abdominal obesity (lager waist circumpherence), atherogenic dyslipidemia (low value of HDL-cholesterol and increased level of triglycerides), increased fasting blood glucose (or type 2 DM diagnosis), higher blood pressure or antihypertensive therapy. In 2009 there were created harmonizing criteria for MS definition; the condition for assignment of MS is the presence of any 3 criteria of 5 mentioned above. The underlying disorder of MS is an insulin resistance or prediabetes. The patients with MS more frequently have subclinical (preclinical) target organ disease (TOD) which is the early sings of atherosclerosis. Increased aortic stiffness is one of the preclinical diseases and is defined by pathologically increased carotidofemoral pulse wave velocity in aorta (PWV Ao). With the aim to assess the influence of MS on aortic stiffness we examined the group of women with arterial hypertension and MS and compare them with the group of women without MS. PATIENT AND METHODS: The aortic stiffness was examined by Arteriograph--Tensiomed, the equipment working on the oscillometric principle in detection of pulsations of brachial artery. This method determines the global aortic stiffness based on the analysis of the shape of pulse curve of brachial artery. RESULTS: From the cohort of 49 pts 31 had MS, the subgroups did not differ in age or blood pressure level. The mean number of risk factors per person in MS was 3.7 comparing with 1.7 in those without MS. In the MS group there was more frequently abdominal obesity present (87% vs 44%), increased fasting blood glucose (81% vs 22%) and low HDL-cholesterol level. The pulse wave velocity in aorta, PWV Ao, was significantly higher in patients with MS (mean value 10,19 m/s vs 8,96 m/s without MS). CONCLUSION: The higher PWV Ao indicates a higher aortic stiffness in patients with MS and more severe subclinical target organ damage of cardiovascular system.

The first record of a natural hybrid of the roach Rutilus rutilus and nase Chondrostoma nasus in the Danube River Basin, Czech Republic: morphological, karyological and molecular characteristics.

Morphological (meristic and morphometric traits), karyological and molecular (microsatellites, cytochrome b) analyses were performed to characterize a hybrid of the roach Rutilus rutilus and nase Chondrostoma nasus. Meristic and morphometric traits were different between hybrid and both parental species. The number of chromosomes found in hybrid specimen indicated that this individual represents the post-F(1) generation of hybrids and the microsatellite analysis of the hybrid showed the presence of variants typical for R. rutilus and C. nasus.

Interactions between immunocompetence, somatic condition and parasitism in the chub Leuciscus cephalus in early spring.

Relationships between immunocompetence, somatic condition, parasitism and water temperature in a wild population of chub Leuciscus cephalus were investigated. The effects of a rapid temperature increase in early spring were studied for both sexes as water temperature affects immunocompetence. Investment in gonads and activity of mucus lysozyme were negatively correlated; lysozyme activity decreased as temperature increased. No correlations were found between lysozyme activity and parasitism or intensity of infection by monogeneans, the most abundant metazoan parasite group in L. cephalus. There was a positive correlation, however, between respiratory burst intensity and parasitism. Indices of investment in gonads and spleen were correlated, showing that energetic reserves allowed either investment in gonads and spleen, or that spleen investment, even if often used in other studies in immunoecology, was not always a significant indicator of immunocompetence during this period. This last proposition is supported by the lack of correlation between spleen investment and other factors linked to immunocompetence.

Metazoan parasites of freshwater cyprinid fish ( Leuciscus cephalus): testing biogeographical hypotheses of species diversity.

The diversity and similarity of parasite communities is a result of many determinants widely considered in parasite ecology. In this study, the metazoan parasite communities of 15 chub populations (Leuciscus cephalus) were sampled across a wide geographical range. Three hypotheses of biogeographical gradients in species diversity were tested: (1) latitudinal gradient, (2) a 'favourable centre' versus 'local oasis' model, and (3) decay of similarity with distance. We found that the localities in marginal zones of chub distribution showed lower parasite species richness and diversity. A latitudinal gradient, with increasing abundance of larvae of Diplostomum species, was observed. There was a general trend for a negative relationship between relative prevalence or abundance and the distance from the locality with maximum prevalence or abundance for the majority of parasite species. However, statistical support for a 'favourable centre' model was found only for total abundance of Monogenea and for larvae of Diplostomum species. The phylogenetic relatedness of host populations inferred an important role when the 'favourable centre' model was tested. Testing of the hypothesis of 'decay of similarity with geographical distance' showed that phylogenetic distance was more important as a determinant of similarity in parasite communities than geographical distance between host populations.

Dactylogyrus species parasitizing European Barbus species: morphometric and molecular variability.

The aims of the study were (1) to describe the Dactylogyrus communities living on selected South European Barbus species, (2) to analyse morphometric variability of their attachment and reproductive organs, and (3) to perform molecular phylogenetic analyses, in order to investigate the mode of speciation in Dactylogyrus species parasitizing congeneric hosts. In Bulgaria, Dactylogyrus crivellius, D. dyki and D. petenyi were found on B. balcanicus, and D. dyki on B. cyclolepis. In Spain, Dactylogyrus carpathicus and D. dyki were detected on B. meridionalis. Morphometric analyses of D. dyki revealed significant differences in the attachment and reproductive organs when individuals from different Barbus species were compared. Two monophyletic groups were recognized from the molecular phylogenetic analyses: the first included D. carpathicus and D. crivellius which have large body size and anchors, with a weakly supported basal position of D. malleus from B. barbus; the second included D. dyki and D. petenyi which have small body and anchor sizes. The comparison of host and parasite phylogenies did not indicate the intrahost speciation. Intraspecific molecular variability was found between individuals of D. dyki and D. carpathicus from different Barbus species, suggesting the need for a taxonomic revision for these species.

A molecular phylogeny of the Dactylogyridae sensu Kritsky & Boeger (1989) (Monogenea) based on the D1-D3 domains of large subunit rDNA.

Phylogenetic analyses based on the partial large subunit rDNA (LSU) sequences of polyonchoinean monogeneans belonging to the Dactylogyridea and Monocotylidea were generated to investigate relationships among various subfamilies of the Dactylogyridae sensu Kritsky & Boeger, 1989. Monophyly of the Dactylogyridae was supported by all analyses performed. Status of the Ancyrocephalidae sensu Bychowsky & Nagibina, 1978 and Ancyrocephalinae sensu Kritsky & Boeger, 1989 was revised based on the present data. All phylogenetic analyses indicated polyphyletic origins of the Ancyrocephalidae and Ancyrocephalinae. Freshwater species of Ancyrocephalinae (Actinocleidus, Ancyrocephalus, Cleidodiscus and Urocleidus) and Ancylodiscoidinae (Thaparocleidus) collected from the fish in European waters were positioned at the base of the Dactylogyridae. The Dactylogyrinae formed a monophyletic group, sister to a clade including the Pseudodactylogyrinae and the tropical and subtropical Ancyrocephalinae. Analyses including only data set on Dactylogyridea were focused on relationships between representatives of the Asian and European Dactylogyrus species. Dactylogyrus species formed a monophyletic group, and the parasite colonization appeared to follow the dispersal history of the Cyprinidae from Asia to Europe. Three lineages of Dactylogyrus species were recognized: the first including species specific to hosts of Asian origin, the second by Dactylogyrus species from Chinese fish hosts, and the third included Dactylogyrus species from European cyprinids and one species from a percid host. The position of D. cryptomeres from Gobio gobio seems to be unresolved.

Posthodiplostomum cuticola (Digenea: Diplostomatidae) in intermediate fish hosts: factors contributing to the parasite infection and prey selection by the definitive bird host.

Infection parameters of Posthodiplostomum cuticola, a digenean parasite with a complex life-cycle, were investigated in fish (the second intermediate host) from 6 floodplain water bodies over 2 years. A broad range of factors related to abiotic characteristics of localities, density of the first intermediate (planorbid snails) and definitive (wading birds) hosts and fish community structure were tested for their effects on P. cuticola infection in juvenile and adult fish. Characters of the littoral zone and flood duration were found to be important factors for the presence of the first intermediate and definitive hosts. Visitation time of definitive bird hosts was also related to adult fish host density. Localities with P. cuticola infected fish were visited by a higher number of bird species. Infection of P. cuticola in fish and similarities in infection among fish host assemblages were correlated with fish host density and fish species composition. Parasite infection in both adult and juvenile fishes was associated with the slope of the bank and the bottom type, in particular in juvenile fish assemblages with snail host density. We conclude that habitat characteristics, snail host density and fish community structure contribute significantly to P. cuticola infection in fish hosts.

The microhabitat distribution of two Dactylogyrus species parasitizing the gills of the barbel, Barbus barbus.

The microhabitat distribution of two congeneric species Dactylogyrus carpathicus and D. malleus (Monogenea) parasitizing the gills of the barbel (Barbus barbus L.) was investigated. We tested whether congeneric species exhibited microhabitat preference and whether interspecific interactions could be attributed to the microhabitat segregation of congeners. The outlying mean index method was used to evaluate species microhabitats. Gill variables (different microhabitats within gills) were used as environmental factors characterizing the gills. When abundances of both species were highest, and no significant difference was found between the abundance of the two species, the gill segments and gill areas were the most important factors segregating the Dactylogyrus species on the gills. Niche overlap was low within each of the four gill arches, and parasites were segregated in the same microhabitats within each gill arch. When abundances of both species were low, each monogenean species was segregated at the level of the gill arches. When abundances of both species increased, the niche and overlap between species increased. The distribution of both congeneric species confirmed microhabitat preference within the gills. The results suggest that microhabitat preference is dependent on species abundances, species being segregated in the case of low abundance, possibly to increasing mating opportunities. Both niche and overlap between species increased with species abundance. In the case of the high abundance of both species, microhabitat preference seems to be related to interspecific interactions between monogenean species, as previously found for endoparasitic species.

Occurrence of intermediate hosts and structure of digenean communities of the black-headed gull, Larus ridibundus (L.).

The factors contributing to the similarity between digenean parasite assemblages parasitizing the black-headed gull were investigated. Thirteen different digenean species from the digestive tract and the bursa of Fabricus were found. We predicted that the structure of parasite communities is not random at either component community or infracommunity levels. We searched for nested patterns in the digenean community, and explored the possible factors contributing to nestedness. We found that digenean species which occupy a narrow range of intermediate hosts are placed out of order in the nested matrix. The influence of several variables related to the water reservoir, geographical distances, and the abundance of intermediate hosts on the species diversity and similarity of parasite communities were tested as well. Because of the complexity in bird digenean life-cycles we supposed that intermediate hosts and ecological characters of their environment could play a major role. We showed that the presence of intermediate hosts is the factor limiting the qualitative and quantitative similarity of parasite communities among different host populations as well as influencing the digenean species diversity in the definitive host. The similarity in abundance of intermediate hosts between different localities was facilitated by the presence of vegetation in water reservoir and more diversified type of water bottom. Digenean species diversity was higher when the water reservoir was exposed to temporal drying. We hypothesized that this factor could facilitate the inclusion of molluscs infected by digeneans in the diet of birds. Both species diversity and dominance were influenced by the bottom type of water reservoir and temporal drying up. Geographical distances between localities influenced the quantitative similarity of digenean communities as well as species richness.

Morphometric correlates of host specificity in Dactylogyrus species (Monogenea) parasites of European Cyprinid fish.

We test the hypothesis that living on larger fish may impose constraints, i.e. the need to develop large attachment organs, related to the necessity to remain attached on large gills. For this, we compiled data on body size and morphometric measurements of attachment organs of 44 Dactylogyrus species (ectoparasites with direct life-cycle) from 19 cyprinid species. Nineteen dactylogyrid species were considered as specialists (infecting only 1 host species) and 25 as generalists (infecting more than 1 species). The lack of phylogenetic information lead us to perform comparative analyses using raw values and independent contrasts obtained by random phylogenies. Our results show that rich parasite communities are formed by specialists and generalists whereas poor communities are composed mainly of generalist parasites. Moreover, specialists are found on larger hosts, which may reflect a specialization on a predictable resource, as larger fish live longer and offer large gills for parasite colonization. Parasite specialization is shown to be linked with adaptation of attachment organs to their fish hosts. Two morphometric variables of the attachment organ, the total length of anchor and length of base of anchor, were positively correlated with host length for specialists.