Phytoplankton successions under ice cover in four lakes located in North-Eastern Sweden: Effects of liming

Phytoplankton successions under ice cover (January–March) were determined in four oligotrophic lakes (Burtjärn, Aspen, Vialamptjärn and Storkorstjärn) located in North-Eastern Sweden. The total phosphorus concentration in the lakes was less than 10 µg/L. Lake Burtjärn (reference lake) had a similar hydrology as Lake Aspen. Storkorstjärn and Vialamptjärn were of similar hydrology and had heavily colored water (>100 mg_Pt/L). Aspen as well as Vialamptjärn became continuously limed with calcium carbonate annually during the last decades. Biodiversity was considerably higher in the limed lakes (Aspen and Vialamptjärn) than in the untreated lakes (Burtjärn and Storkorstjärn). In Lake Burtjärn the most frequent species wereRhodomonas lacustris, Tabellaria flocculosa andBotryococcus braunii. Cryptophyceae (R. lacustris andCryptomonas marssonii) andDinophyceae (especiallyGymnodinium lantzschii) were common phytoplankton groups in Lake Aspen.Tabellaria flocculosa was also the most common organism in both humic lakes Storkorstjärn and Vialamptjärn, other phytoplankton groups were in the humic lakes scarce. Liming was found to have profound effects on phytoplankton communities studied.     

Concurrent evolution of ancient sister lakes and sister species: the freshwater gastropod genus <Emphasis Type="Italic">Radix</Emphasis> in lakes Ohrid and Prespa

Ancient sister lakes are considered to be ancient lakes lying in close geographic proximity, sharing a related origin and significant time of co-existence, usually having hydrological connection as well as a balanced degree of faunal overlap and distinctness. A paradigm for studying sister lake relationships are the ancient lakes Ohrid and Prespa in the Balkans, which are characterized by high degrees of endemicity. Three general patterns of endemic species can be distinguished for these lakes: (1) taxa that are endemic to either lake, with no close relatives in the respective sister lake, (2) closely related but distinct endemic taxa in both lakes (sister species) and (3) shared endemic taxa occurring in both lakes. In the present paper, two endemic freshwater pulmonate gastropod species, Radix relicta (Lake Ohrid) and R. pinteri (Lake Prespa), are used to study the evolution of presumed sister species based on biogeographical and comparative DNA data from world-wide Radix taxa. Phylogenetic, phylogeographical and parametric bootstrap analyses all suggest a sister group relationship of R. relicta and R. pinteri (pattern 2 of endemic diversity). Sister to these two taxa is the widespread R. ampla, which does not occur in the vicinity of lakes Ohrid and Prespa. The southern feeder spring complexes of Lake Ohrid are inhabited by another lineage (Radix sp. 1), which resembles Radix relicta in morphology/anatomy. For Lake Prespa, the widespread R. auricularia was reported in addition to the endemic R. pinteri. Comparative phylogenetic data favour a western Adriatic zoogeographical affinity of lakes Ohrid and Prespa over an Aegean-Anatolian faunal connection. The status of lakes Ohrid and Prespa as sister lakes is evaluated in the light of current knowledge on gastropod speciation and endemism in these hotspots of biodiversity.     

New host species and new distribution areas of <Emphasis Type="Italic">Salmincola lavaretus</Emphasis> (Copepoda: Lernaeopodidae): A parasite of coregonid fishes of Siberia

Data on the infestation of certain fish species by the parasitic copepod Salmincola lavaretus are presented for the first time. The infested fish species included Bauntovsky whitefish (Coregonus baunti), an endemic species from the Maloye and Bolshoye Kapylyushi lakes; Siberian whitefish (C. pidschian) and Siberian cisco (C. sardinella) from Bolshoye Kapylyushi Lake and Baunt Lake, which belong to the Tsypo-Tsypikan lake system (the Lena River basin, Transbaikalia); and Teletsky whitefish (C. lavaretus natio smitti) from Teletskoe Lake (the Ob River basin). Previously, S. lavaretus had been described as a parasite of Baikal omul (C. migratorius) and Baikal whitefish (C. baicalensis) from Baikal. The taxons of S. longimanus complex (S. longimanus, S. l. sibirica, S. svetlanovi, and S. lavaretus)—parasites of nasal fossae of grayling and coregonid fishes—were registered in the lakes of the Lake Baikal basin (Lake Baikal and Khovsgol Lake), the Lena River, the Yenisei and the Ob rivers (the largest rivers of the Arctic zoogeographic province), and the Kobdo River (the Western Mongolian province). It was assumed that S. longimanus complex is more widely distributed in the water bodies of the Arctic zoogeographic province of the Palearctic.     

Development of subfossil <Emphasis Type="Italic">Daphnia</Emphasis> and <Emphasis Type="Italic">Chaoborus</Emphasis> assemblages in relation to progressive acidification and fish community alterations in SW Sweden

Dated sediment cores from acidified and fishless Lake Gaffeln and Lake Härsvatten, SW Sweden, were analyzed for Daphnia ephippia and Chaoborus mandibles to test whether acidification history and fish extirpations could be reconstructed in a paleo-study using these easily identifiable animal remains. According to monitoring data fish were lost in both lakes from the 1950s to the 1970s. Progressive acidification prior to monitoring was confirmed by a gradual decrease and eventual loss of Daphnia ephippia in both study lakes during the first half of the twentieth century. In Lake Gaffeln mandibles of C. obscuripes appeared immediately after fish loss in 1973, and the regular presence of this species confirmed the succeeding fishless state of this lake. In Lake Härsvatten sediments C. obscuripes appeared only recently, i.e. three decades after fish extirpation, showing that the absence of C. obscuripes mandibles is not a trustworthy indicator of fish presence. Hence, the appearance of C. obscuripes was not temporally related to fish loss but confirmed the present fishless condition. Known historical presence of cyprinid fish in Lake Gaffeln was confirmed by a significantly higher proportion of fragmented mandibles of C. flavicans compared to the historically cyprinid-free Lake Härsvatten. In addition, both lake profiles displayed zero-proportions of fragmented mandibles during fishless periods. We conclude that acidification history and fish extirpations can be inferred by integrated studies on subfossil Daphnia ephippia and Chaoborus mandibles. However, during extreme ultra-oligotrophic conditions in acidified clear-water lakes subfossil Chaoborus mandibles may be too scarce to infer fish absence/presence.     

Sitting ducks: diet of wintering wildfowl in Lake Tonga,northeast Algeria

Dietary studies of five species of Anatidae (Gadwall Anas strepera, Shoveler Anas clypeata, Pochard Aythya ferina, Ferruginous Duck Aythya nyroca, and White-headed Duck Oxyura leucocephala) were carried out at Lake Tonga, northeast Algeria, from December 2011 to March 2012. Diet analysis of all five wintering species indicated a heavy reliance on seeds, which included a wide variety of aquatic plants, such as Myriophyllum spicatum, Ceratophyllum demersum, Sparganium erectum, Scirpus lacustris and Potamogeton pectinatus. Noteworthy is the paucity of ingested macroinvertebrates. Despite dietary overlap, the type, abundance and frequency of food consumed clearly indicated differences in resource use among the ducks. Incidentally, the study also highlighted the high vulnerability of threatened ducks to poaching (harvesting and disturbance) in a protected area. We discuss the implications of these findings for the management and conservation of wintering wildfowl and their North African habitats.     

Identification of extremely halophilic archaea associated with adult <Emphasis Type="Italic">Artemia urmiana</Emphasis>

The brine shrimp, Artemia is the dominant macrozooplankton present in many hypersaline environments. Artemia urmiana is the only macroscopic organism in Urmia Salt Lake (Iran), and the high salinity of the lake makes it a suitable environment for halophilic archaea too. Because of common environment for Artemia and extreme halophiles; this investigation is concentrated on studying the relationship between Artemia and halophilic archaea in Urmia Lake. In this study first the procedure of arhaea isolation was done. Then, isolated strains were sub-cultured and DNA was extracted and amplified by PCR using specific primers for amplifying archaeal 16S rRNA. The amplified archeal DNA fragments were purified, and sequenced. 16S rRNA sequences were compared to known sequences using the NCBI BLAST program. Sequences relating to Halorubrum, Haloarcula and Halobacterium species were identified in Urmia Salt Lake water and Artemia adults and the phylogenetic tree of different species was constructed. Only Halorubrum species were present in association with Artemia. They belong to Halobacteriaceae family of archeae which are isolated from different salt lakes in different parts of world and we could show their existence in adult Artemia, another organism living in hypersaline enviroments.     

Live labeling technique reveals contrasting role of crustacean predation on microbial loop in two large shallow lakes

We tested the hypotheses that the ciliate assemblages in moderately eutrophic lake are controlled by the effective crustacean predation, and the high abundances of planktonic ciliates in highly eutrophic and turbid lake are due to insufficient regulation by crustacean zooplankton. A food tracer method coupled with natural assemblage of microciliates labeled with fluorescent microparticles was used to measure the cladoceran and copepod predation rates on planktonic ciliates and to estimate the carbon flow between the ciliate–crustacean trophic links. The results revealed that the microciliates (15–40 μm) were consumed by all dominant cladoceran and copepod species in both the lakes studied, mainly by Chydorus sphaericus and cyclopoid copepods in Lake Võrtsjärv, and by Daphnia spp. and Bosmina spp. in Lake Peipsi. The grazing loss in moderately eutrophic Peipsi indicated strong top-down control of ciliates mainly by cladocerans. The extraordinary abundant population of planktonic ciliates having a predominant role in the food web in highly eutrophic and turbid Võrtsjärv is explained by the measured low crustacean predation rates on ciliates. The estimated carbon flow from the ciliates to crustaceans suggest that in eutrophic lakes majority of the organic matter channeled via metazooplankton to higher trophic levels may originate from the microbial loop.     

The impact of the invasive Ponto-Caspian amphipod <Emphasis Type="Italic">Pontogammarus robustoides</Emphasis> on littoral communities in Lithuanian lakes

The intentionally introduced Pontogammarus robustoides is the most successful amphipod invader of Lithuanian inland waters and has become established in large lakes. Its impact on littoral invertebrate communities was studied by comparing similar habitats across lakes that harbour or are devoid of the invader. In habitats where P. robustoides is well established and numerous, it significantly reduces species richness and community diversity. Moderate pontogammarid density in habitats that can sustain the native gammarid Gammarus lacustris, however, revealed no negative impact on diversity metrics. Among the lakes studied, the benthic biomass did not differ in invaded and uninvaded habitats. The biomass of indigenous invertebrates (excluding chironomids, which exhibited high lake-specific biomass variation) was lower in the places with well-established P. robustoides. A detrimental impact was observed upon the native isopod Asellus aquaticus and a negative correlation with most of the higher taxa of native invertebrates. In the invaded lake habitats that favour P. robustoides, a change in community structure and a decrease in diversity up to twofold or more are to be expected.     

Decrease in young-of-the-year yellow perch growth rates following <Emphasis Type="Italic">Bythotrephes longimanus</Emphasis> invasion

Bythotrephes longimanus, an invasive zooplankter from Eurasia, has caused severe declines in native zooplankton communities in Rainy and Kabetogama lakes in northern Minnesota. Both lakes have experienced a 40–60% decrease in peak summer zooplankton biomass following B. longimanus establishment around 2006–2007. In these lakes, yellow perch (Perca flavescens) are a key fishery species, and young-of-the-year (YOY) yellow perch are mainly planktivorous during their first summer. This led to concern that their growth could be detrimentally affected by the depletion of zooplankton forage. We used seining data to compare growth rates of YOY yellow perch before (2001–2005) and after (2008–2012) B. longimanus establishment in Rainy and Kabetogama lakes. Nearby Lake Vermilion, assumed to have been unaffected by B. longimanus during this time period, was used as a reference for natural variation in YOY growth in the region. YOY yellow perch length was modeled as a linear function of cumulative growing degree days (GDD) throughout the summer, and the slope of the relationship was compared between pre- and post-B. longimanus time periods for the three study lakes. The two lakes with B. longimanus showed similar decreases in YOY yellow perch growth rate relative to GDD, whereas Lake Vermilion showed no evidence of a decline in growth rates during this period. The reduction in growth rates resulted in an approximate 10% decrease in mean length of YOY yellow perch at the end of the summer after B. longimanus establishment, which could lead to further effects of this invasive zooplankter at higher trophic levels.     

On the diversity of fishes in mountain lakes of the Amur basin

Results of the study of 11 lakes situated in the mountainous part of the Amur River basin are reported. Six fish species, namely, blunt-snouted lenok Brachymystax tumensis, Baikal-Lena grayling Thymallus baicalolenensis, Siberian stone loach Barbatula toni, Lagowski’s minnow Rhynchocypris lagowskii, Czekanowski’s minnow Rh. czekanowskii, and Amur sculpin Cottus szanaga, were found in five lakes. Four species were found in one lake (Lake Pereval’noe, basin of the Amgun’ River), and two species were found in each of the remaining lakes. Lenok and Amur sculpin were the most common species. The fauna of Lake Okonon (basin of the river Zeya) was the most specific and did not have analogs among the lake faunas; Czekanowski’s minnow and Baikal black grayling were found in this lake. The lenok ecotype that formed in the mountain lakes differed from the river lenok in some regards. The potential pathways of formation and protection of mountain lake ichthyocenoses of the Amur basin are discussed.     

Restoration of zooplankton in a small acidified mountain lake (Plešné Lake,Bohemian Forest) by reintroduction of key species

Atmospheric acidification brought about the extinction of several species of planktonic Crustacea in lakes of the Bohemian Forest (?umava, Böhmerwald). The recent reversal in chemical parameters of lake water towards pre-acidification values raises the question whether the return of missing species is possible. We have designed a bioassay to test water from different lakes for the survival of Daphnia longispina, which inhabited the lakes under study but disappeared from those most affected by acidification. The bioassay showed the best survival in water from Ple?né Lake, one of those where Daphnia and Cyclops became extinct. A large-scale experiment was conducted by transplanting Daphnia longispina (Crustacea, Cladocera) and Cyclops abyssorum (Crustacea, Copepoda) from Prá?ilské Lake, where they have survived until the present, to Ple?né Lake. One year later, a successful reintroduction was confirmed for Cyclops abyssorum.     

Secondary contact between two divergent lineages of charrs of the genus <Emphasis Type="Italic">Salvelinus</Emphasis> in the Northwest Pacific

The present-day contact zone between the Beringian and Arctic phylogenetic lineages of charrs of the genus Salvelinus in the Northwest Pacific is documented. A comparative analysis of the genetic differentiation and divergence indices for allopatric and sympatric populations of charrs and phylogenetic and genealogical analyses of the mtDNA haplotypes indicate that Lake Achchen and the Lake Pekulineiskoe are the zones of secondary contact between S. m. malma and S. taranetzi; Lake Nachikinskoe, between S. m. malma and Salvelinus sp. 4; and Lake Dal’nee, between S. m. malma and S. krogiusae. The level of divergence between phylogenetic groups of haplotypes considerably exceeds the range of intraspecific variability of S. m. malma and could not have been achieved after colonization of the lakes in conditions of sympathy. The obtained data suggest that the territory of Kamchatka was colonized by the common ancestor of the Arctic phylogroup of Taranetz charr.     

A laboratory study of host use by the cuckoo catfish <Emphasis Type="Italic">Synodontis multipunctatus</Emphasis>

The only known non-avian vertebrate obligate brood parasite is the cuckoo catfish (Synodontis multipunctatus), a Lake Tanganyikan endemic. The cuckoo catfish parasitizes Tanganyikan mouthbrooding cichlids, and under captive conditions, will also parasitize cichlids from other Rift Valley lakes. Here we examine the frequency of parasitism by the cuckoo catfish of Ctenochromis horei from Lake Tanganyika and three species from Lake Malawi and the greater Lake Victorian system in a laboratory setting. C. horei was parasitized significantly less (17%) than the allopatric species Haplochromis latifasciatus, Haplochromis nubilus, and Metriaclima estherae (combined parasitism rate of 28%). The lower rates of parasitism in C. horei may be due to differences in the mating ritual, oviposition (e.g., long periods of pseudo-spawning before actual oviposition), and behavioral adaptations (e.g., increased aggression towards the cuckoo catfish). The number of catfish eggs per parasitized brood was similar between C. horei, H. latifasciatus, H. nubilus, and M. estherae. Our results are comparable to findings from the field for C. horei parasitism frequency and number of cuckoo catfish per brood. We also analyzed the parasitism rate of the albino morph of Metriaclima zebra, a domestic strain. Parasitism rates and number of catfish per brood were the highest in the albino morphotype suggesting that the higher levels of parasitism may be related to lower aggressive behavior, lower visual acuity, or captive influence. Cuckoo catfish and mouthbrooding cichlids provide a model system for testing brood parasitism in a laboratory setting.     

New species of the buprestid genus <Emphasis Type="Italic">Endelus</Emphasis> Deyrolle (Coleoptera,Buprestidae) from China,India, and Laos

Endelus (Kubaniellus) indicus sp. n. from India, E. (K.) lao sp. n. and E. (K.) khnzoriani sp. n. from Laos, E. (s. str.) sausai sp. n. from China, and E. (s. str.) dembickyi sp. n. from India are described, the two latter species are included in the Endelus bicarinatus Théry, 1932 species-group recently established by the author. E. collinus Obenberger, 1922 is included in this group; lectotype of this species is designated. Keys to species of the subgenus Kubaniellus and of the E. collinus group are provided. E. (K.) kareni Kalashian is for the first time recorded for Shaanxi Prov., E. pacholatkoi Kalashian, E. smaragdinus Desc. et Vill., and E collinus Obenb., for Laos (the latter species, also for Myanmar).     

Testing two contrasting evolutionary patterns in ancient lakes: species flock versus species scatter in valvatid gastropods of Lake Ohrid

Ancient lakes have long been recognized as “hot spots of evolution” and “evolutionary theatres” and they have significantly contributed to a better understanding of speciation and radiation processes in space and time. Yet, phylogenetic relationships of many ancient lake taxa, particularly invertebrate groups, are still unresolved. Also, the lack of robust morphological, anatomical, and phylogeographical data has largely prevented a rigorous testing of evolutionary hypotheses. For the freshwater gastropod genus Valvata—a group with a high degree of endemism in several ancient lakes—different evolutionary scenarios are suggested for different ancient lakes. Lake Baikal, for example, is inhabited by several endemic Valvata taxa that presumably do not form a monophyletic group. For such an evolutionary pattern, the term ancient lake species scatter is introduced here. In contrast, for the Balkan Lake Ohrid, workers previously suggested the presence of a monophyletic group of endemic Valvata species, that is, an ancient lake species flock. Sequence data of the mitochondrial cytochrome oxidase c subunit I gene (COI) from worldwide taxa, with a strong emphasis on Balkan species, are here used to test whether the putative Ohrid Valvata endemics represent an ancient lake species flock and to study patterns of speciation both on the Ohrid and the Balkan scale. The study reveals three distinct clades of endemic Valvata in Lake Ohrid. Monophyly of these taxa, however, is rejected, and they therefore do not represent an ancient lake species flock, but rather an ancient lake species scatter. Also, in contrast to many other gastropod groups in Lake Ohrid, the valvatids apparently did not radiate. Many Valvata taxa in ancient lakes are characterized by enhanced levels of shell complexity. However, it remains unclear whether these patterns are associated with ancient lake environments per se. It is here suggested that similarities in shell structure between North American and Balkan taxa might simply be due to convergent evolution.     

The Afromontane Cladocera (Crustacea: Branchiopoda) of the Rwenzori (Uganda–D. R. Congo): taxonomy,ecology and biogeography

The timely characterization of high-altitude freshwater habitats allows an assessment of the diversity of its biota and provides the basis for monitoring community change. In this study, we investigate the Cladocera fauna of 29 water bodies (pools, freshwater lakes, and surrounding swamps sampled at various occasions between 2005 and 2009) in the Rwenzori Mountains (Uganda, D. R. Congo), which are part of the East African Sky Island Complex. All sites except one are located above 3700 m altitude. We include notes on the morphology, taxonomy, distribution, and ecology of each recorded taxon and describe a new species of the Alona rustica-group (Alona sphagnophila n.sp.; Chydoridae). We found 11 species of which seven are restricted to Lake Mahoma, the lowest lake in our study area (2990 m) (Alona affinis barbata, A. intermedia, Alonella exisa, Alonella nana, Daphnia cf. obtusa, Pleuroxus aduncus) and/or Lake Bujuku (Daphnia cf. curvirostris, P. aduncus) (3900 m). Two taxa (Ilyocryptus cf. gouldeni, A. sphagnophila n.sp.) are restricted to Carex/Sphagnum bogs surrounding lakes in the afroalpine zone. Pigmented populations of Chydorus cf. sphaericus occur in all the sites. It is the only cladoceran species surviving the extreme alpine and nival conditions in the Rwenzori. The species is joined by A. guttata at locations at lower altitudes (ca. 3000–4000 m), present in about half of the sites. The Rwenzori Cladocera fauna is characterized by a strong extratropical temperate component and a low level of speciation/endemism. Harboring an impoverished boreal cladoceran community, Lake Mahoma is given closer attention. At 2990 m, the lake is a cold-temperate aquatic island in the tropics and may function as a stepping stone for Palaearctic taxa. We introduce a new term for high-altitude, cold-water habitats in the tropics, which act as climatic islands for extratropical freshwater faunas, Löffler Islands, in honor of Dr Heinz Löffler. In comparison to surveys in 1961, we list five new records in Lake Mahoma, which could indicate cladoceran community changes over the past few decades at ca. 3000 m in the Rwenzori. Since the species distributions correlate to temperature and catchment properties of the lakes, the Rwenzori cladoceran fauna can be expected as sensitive indicators for local changes.     

mtDNA-based identification of two widespread roach species (<Emphasis Type="Italic">Rutilus</Emphasis>, Cyprinidae) characterized by sympatric zone

Test systems using multiplex PCR and restriction analysis have been designed for the simple and rapid identification of two widespread species of roach, Rutilus rutilus and R. lacustris, characterized by the sympatric zone. This method is based on the variation of nucleotide sequences of the mitochondrial markers (cytochrome oxidase I subunit and cytochrome b); it allows identifying the species omitting the DNA sequencing.     

Specific features of ecology of chars of the genus <Emphasis Type="Italic">Salvelinus</Emphasis> (Salmonidae) from the basin of Lake Kronotskoe (Kamchatka) according to parasitological data

A parasitological study was performed of chars of the genus Salvelinus inhabiting Lake Kronotskoe (Kamchatka Peninsula)—S. malma, S. albus, S. schmidtii, and S. kronocius, as well as of juvenile Salvelinus spp. Twenty-three species of parasites, including six species new for the lake, Hennequya zschokkei, Protteocephalus longicollis, Diphyllobothrium dendriticum, Crepidostomum sp., Echinorhynchus salmonis, and Paracanthobdella livanowi, were found. With consideration of published data, in chars of this water body, 28 species of parasites were recorded, including seven species (N. cf. pungitius, B. luciopercae, Crepidostomum sp., Cr. fausti, Cr. cf. cooperi, Eubothrium crassium, and Proteocephalus sp.), whose presence or species identification in the lake ecosystem need confirmation. Two species (N. rutili and Diphyllobothrium sp.) are removed from the list. Parasites common for all species of chars were revealed. They include Myxobolus arcticus, E. salvelini, D. ditretum, Crepidostotum sp., Cr. farionis, Cr. metoecus, Cystidicola farionis, Cucullanus truttae, Philonema oncorhynchi, and Salmincola carpionis. Cluster analysis of the fauna of parasites of different species of chars demonstrated considerable differences in infestation, which indicates differences between them in preference for food items and occupied biotopes and thereby supports the ecological differentiation of chars in the basin of Lake Kronotskoe. S. albus and S. kronocius are most similar in parasitofauna, which is determined by their predation; S. malma as a benthophage is infected by the same species of parasites, but considerably less intensively. Extremely high indices of population numbers of some parasite species are considered as a manifestation of the Krebs cycle in parasites under the conditions of an isolated lake.     

Ecology of <Emphasis Type="Italic">Gammarus lacustris</Emphasis> Sars (Crustacea: Amphipoda) in Transbaikalian water bodies

The data on Gammarus lacustris Sars, 1863 ecology in Transbaikalian water bodies was integrated by the example of Lakes Khalanda, Bain-Tsagan, Arakhlei, Zun-Torei, and Bain-Bulak. The impact of the major environmental factor on the pattern of G. lacustris spatial distribution, linear size, growth rate, time of reaching sexual maturity, and number of reproduced generations was shown. The role of G. lacustris in the ecosystem of studied water bodies was evaluated and the adaptive significance of the revealed life strategies was considered.     

Complementary description of <Emphasis Type="Italic">Ergasilus arthrosis</Emphasis> Roberts, 1969 (Copepoda: Poecilostomatoida: Ergasilidae), a new parasite of cichlid teleosts in southeast Mexico

During a parasitological survey of the ichthyofauna of Lake Catemaco, a freshwater system in the Mexican State of Veracruz, the widespread copepod Ergasilus arthrosis Roberts, 1969 was recovered from two cichlid teleosts, Mayaheros urophthalmus (Günther) and Oreochromis sp. This is the first confirmed record of this copepod species outside of the United States and from Mexico; its finding as a parasite of cichlids represents an expansion of the known host range for this copepod. The local prevalence and intensity of infection of E. arthrosis was highest in M. urophthalmus. The infection prevalence of E. arthrosis on M. urophthalmus (60%) was higher than that known for other ergasilids on cichlids. Ergasilus arthrosis can be distinguished from its closest congener E. lizae Krøyer, 1863 by the morphometry of the antennary segments, the ventral ornamentation of the thoracic sclerites and by details of the antennulary setation, but also by its habitat and host preferences. Taxonomic illustrations and morphological details of the specimens examined are also provided together with comments on the variability of this species.