Halacarid Mites Research Articles

Molecular phylogenetic relationships of halacarid mites suggest the reevaluation of traditional subfamily classification

Molecular phylogenetic relationships were examined for marine mites in the subfamilies Halacarinae, Copidognathinae, Rhombognathinae and Halixodinae from the aquatic mite family Halacaridae by using nuclear 18S and 28S ribosomal RNA gene sequences. The analysis revealed incongruences between the clustering obtained in the phylogenetic trees and the current morphological classification in the subfamilies Halacarinae and Rhombognathinae (based on 18S sequences) and in the Rhombognathinae (based on both 28S and combined 18S and 28S sequences). By contrast, the tree clustering was consistent with the morphological taxonomic positions in the Copidognathinae and Halixodinae subfamilies. It can be concluded that molecular phylogenetic analysis challenges the current classifications of Halacarinae and Rhombognathinae subfamilies. Accordingly diagnostic characters for their classification should be reevaluated.

Epibiotic mites associated with the invasive Chinese mitten crab Eriocheir sinensis – new records of Halacaridae from Poland

Seven epibiotic halacarid mites (Caspihalacarus hyrcanus, two species of Copidognathus, Halacarellus petiti, Porohalacarus alpinus, Soldanellonyx monardi and S. chappuisi), two oribatid mites (Hydrozetes lacustris and Trhypochthoniellus longisetus) and one water mite (Piona pusilla) were found on the setae-covered claws of eighteen Chinese mitten crabs (Eriocheir sinensis) collected from fresh and brackish waters in Poland and Germany. The most abundant of the 111 mite individuals recorded was one of the Copidognathus species (N=52); this was followed by H. petiti (N=38) and C. hyrcanus (N=13). This is the first record of H. petiti and of the genus Copidognathus from Polish waters. The possibility of migrating over long distances assisted by catadromous mitten crabs enhances mite dispersal, as well as their introduction to new environments.

Upper littoral rhombognathines (Acari: Halacaridae) from Singapore: description of a new species

In the upper tidal zone, which is uncovered most of the day, halacarid mites may numerically play a major role. Two genera, often present in algal films in this zone, are Rhombognathus and Isobactrus. One of the Rhombognathus species found in Singapore mangroves proved to be new to science. This species, Rhombognathus amplus n. sp., is described and compared with two closely related species, both known from mangroves, one from Singapore, the other from Hong Kong.

Invertebrate Fauna Associated with Floating Sargassum horneri (Fucales: Sargassaceae) in the East China Sea

The invertebrate fauna associated with floating Sargassum horneri (Turner) C. Agardh, 1820 in the East China Sea was investigated in terms of ecology and biogeography. Floating algal rafts consisting of only S. horneri were collected at 16 stations in the East China Sea during a cruise of research vessel (R/V) Tansei-Maru in February, 2011. A total of 53 rafts were obtained for faunal investigations at 14 of the 16 stations. In addition to fish eggs, 10 invertebrate taxa were found on the floating algae. Of the collected phytal animals, harpacticoid copepods were most abundant in terms of number (80%), followed by cirripedes (15%), amphipods (4%), and others (1%). The faunal diversity on the algae was correlated to the algal weight. The faunal diversity differed significantly between stations and was highest in the northernmost part of the East China Sea. Density and abundance of animals were highest in areas close to the Kuroshio Current. Considering the direction of flow of the Kuroshio Current and the density of cirripedes immigrating from the surrounding water onto the floating algae, most of the floating S. horneri possibly originated in the southern part of the East China Sea. On the other hand, the Sargassum rafts collected in the northernmost part of the East China Sea could have originated from the coast of eastern China. Most of the animals found on the floating Sargassum were pelagic taxa that complete their life cycles on the rafts in situ. Typical coastal animals, including gammaridean and caprellidean amphipods, tanaidaceans, nematodes, gastropods, polychaetes, halacarid mites, bryozoans, and hydrozoans, were also obtained from the floating Sargassum , but only occasionally and their densities were quite low. These facts suggest that dispersal events among benthic habitats via Sargassum rafts are relatively rare.

Checklist of marine and freshwater halacarid mite genera and species (Halacaridae: Acari) with notes on synonyms, habitats, distribution and descriptions of the taxa

At the end of 2007, the family Halacaridae, superfamily Halacaroidea, included 1118 valid species in 63 genera. The genera and the number of species (in parentheses) are: Acanthohalacarus (1), Acanthopalpus (2), Acarochelopodia (8), Acaromantis (11), Acarothrix (5), Actacarus (24), Agaue (42), Agauides (2), Agauopsis (85), Anomalohalacarus (19), Arenihalacarus (1), Arhodeoporus (31), Astacopsiphagus (1), Atelopsalis (7), Australacarus (5), Bathyhalacarus (12), Bradyagaue (17), Camactognathus (3), Caspihalacarus (1), Coloboceras (3), Colobocerasides (2), Copidognathides (3), Copidognathus (359), Corallihalacarus (1), Enterohalacarus (1), Halacarellus (47), Halacaroides (2), Halacaropsis (5), Halacarus (75), Halixodes (3), Hamohalacarus (1), Himejacarus (1), Isobactrus (26), Limnohalacarus (13), Lobohalacarus (6), Lohmannella (36), Metarhombognathus (2), Mictognathus (3), Parasoldanellonyx (3), Parhalixodes (2), Pelacarus (1), Peregrinacarus (2), Phacacarus (1), Porohalacarus (2), Porolohmannella (1), Rhombognathides (6), Rhombognathus (103), Ropohalacarus (1), Scaptognathides (11), Scaptognathus (30), Simognathus (45), Soldanellonyx (9), Spongihalacarus (1), Stygohalacarus (1), Thalassacarus (1), Thalassarachna (14), Thalassophthirius (1), Troglohalacarus (1), Tropihalacarus (2), Werthella (10), Werthelloides (1), Winlundia (2), and Xenohalacarus (1). More than 1000 species live in marine and brackish water and almost 60 species exclusively in fresh or oligohaline to mesohaline brackish water (< S18‰). The checklist presents names used for halacarid genera and species of the world, names recognized as valid, synonyms, nomina nuda, names of species inquirendae and species erroneously attributed to the family Halacaridae. All valid species are supplemented with distributional data, namely, biogeographical provinces, depth zones and habitats, and references of descriptions of genera and species.

An overview of Suctorian ciliates (Ciliophora, Suctorea) as epibionts of halacarid mites (Acari, Halacaridae)

Scant information is available regarding the prevalence and distribution of suctorian ciliates on halacarid mites. However, using this limited information and data from our laboratory on the systematics, biology, ecology and distribution of suctorian ciliates that are epibionts of halacarid mites, we redescribed four suctorian species: Limnoricus ceter (Jankowski), Praethecacineta halacari (Schulz), Thecacineta calix (Schroder) and Acineta sulcata Dons. We also recognized Lissacineta allgeni Jankowski and Thecacineta allgeni (Jankowski) as synonyms of Praethecacineta halacari (Schluz), and Thecacineta laophontis Jankowski and Paracineta moebiusi Kahl as synonyms of Thecacineta calix (Schroder). Many suctorians have been reported, but not properly identified in the halacarid literature. So, we have attempted to identify those suctorians to species level. Lastly, the interactions between the suctorians and their hosts are also discussed and Praethecacineta halacari is also reported for the first time from the Indian coast.

Global diversity of halacarid mites (Halacaridae: Acari: Arachnida) in freshwater

Halacarid mites have successfully invaded the sea and approximately 56 species colonized the freshwater. Invasion from the sea into continental waters probably started in the Mesozoic or Pre-Mesozoic and went on in the following epochs. The number of genera (14) and species (34) recorded from the Palaearctic is remarkably higher than that of other geographical regions. These numbers do not imply that the Palaearctic is a centre of origin, they reflect the sampling activity rather than reliable data on diversity.

Halacaroidea (Acari): A guide to marine genera

Halacarid mites (Halacaroidea: Halacaridae) are meiobenthic organisms. The majority of species and genera are marine, only few are restricted to freshwater. Halacarid mites are present from the tidal area to the deep sea. It is the only mite family completely adapted to permanent life in the sea. The first record was published more than 200 years ago. At present, 51 marine and brackish water genera of halacarid mites are known, including more than 1000 species. The genera are Acanthohalacarus, Acanthopalpus, Acarochelopodia, Acaromantis, Acarothrix, Actacarus, Agaue, Agauides, Agauopsis, Anomalohalacarus, Arenihalacarus, Arhodeoporus, Atelopsalis, Australacarus, Bathyhalacarus, Bradyagaue, Camactognathus, Caspihalacarus, Coloboceras, Colobocerasides, Copidognathides, Copidognathus, Corallihalacarus, Enterohalacarus, Halacarus, Halacarellus, Halacaroides, Halacaropsis, Halixodes, Isobactrus, Lohmannella, Metarhombognathus, Mictognathus, Parhalixodes, Pelacarus, Peregrinacarus, Phacacarus, Rhombognathides, Rhombognathus, Scaptognathides, Scaptognathus, Simognathus, Spongihalacarus, Thalassacarus, Thalassarachna, Thalassophthirius, Tropihalacarus, Werthella, Werthelloides, Winlundia, and Xenohalacarus. The guide, which includes marine and brackish water genera, starts with an introduction to methods of collection, extraction and examination of halacarid mites, an outline of the external morphology and life history, and an overview of the commonly used terminology. Both a dichotomous key and tabular keys to the genera are presented. The keys have been prepared on the basis of adults. In general, in adults and nymphs the outline of idiosoma, gnathosoma and legs is similar, whereas the outline of plates, the sculpturing and number of setae on idiosoma and legs differ. In the tabular keys idiosoma, gnathosoma, palps, legs, tarsi and shape of claws are treated separately. The major part of the guide deals with descriptions of the 51 genera. Each genus is diagnosed and illustrated, namely a dorsal and ventral aspect of the idiosoma, the gnathosoma, leg I and tarsi I, II and IV. The diagnoses mention both, characters expected to be relevant in a phylogenetic sense and those thought to be mainly correlated with environment and mode of life. Rare character variants are included in the diagnoses; more variants are expected to be found in the future. In addition to the diagnoses, short notes are given on biology and geographical distribution, on similar-looking genera, and distinguishing characters. At the end of the presentation of a genus, relevant and most recent descriptive or phylogenetic references are listed. Full article published online at: http://www.senckenberg.de/odes/06-06.htm

Ecological associations between organisms of different evolutionary history: mangrove pneumatophore arthropods as a case study

Typical marine arthropods (crustaceans and halacarid mites), as well as species of recent terrestrial ancestry (insect larvae and mesostigmatid mites) coexist on mangrove pneumatophores. Both groups are affected by desiccation and are less abundant towards the tips of the pneumatophores. The degree of species associations within and between the two groups was investigated. The number of negative associations is higher for marine–marine, as compared to terrestrial–terrestrial and terrestrial–marine species pairs. When environmental stress (as represented by direct sunlight, and elevation on pneumatophores, both resulting in increased desiccation) is considered, associations tend to shift from negative to positive, and this is more obvious in terrestrial–terrestrial species pairs. These results are attributed to the longer co-evolutionary history of the marine species, resulting in a more precise partitioning of the microhabitats, while the relationships between terrestrial species are less stable, and more susceptible to environmental stress.

New records of water mites (Acari: Hydrachnidia and Halacaroidea) from Bosnia and Herzegovina, with description of a new species, Aturus gordani

A presented faunistic catalogue of water mites (Acari: Hydrachnidia and Halacaroidea) from Republic of Srpska (Bosnia and Herzegovina) is based on all published data and numerous new records from the investigated area. Twenty two species were identified, 12 of which new to Bosnia and Herzegovina and one species Mideopsis roztoczensis was recorded for the first time in the Balkans. The species Aturus gordani was described as new to science; halacarid mites were recorded (Acari: Halacaroidea) for the first time in the fauna of Bosnia and Herzegovina. The ecological significance of the new records was briefly discussed.

Diet of Juvenile Lumpsucker Cyclopterus lumpus (Cyclopteridae) in Floating Seaweed: Effects of Ontogeny and Prey Availability

We studied the feeding ecology of juvenile lumpsuckers, Cyclopterus lumpus, during their first year in natural floating seaweed clumps and experimental floating seaweed branches, in southwest Iceland. The juveniles appeared to ignore sessile, slow-moving, and small animals (e.g., ostracods, bivalves, gastropods, oligochaetes, polychaetes, turbellarians, rotifers, and nematodes), while taking most other prey organisms in approximate proportion to availability. Juvenile lumpsuckers in floating seaweed fed mainly on prey organisms found on the seaweed but also consumed organisms from the plankton. Ontogenetic changes in the diet were related to size of prey. Lumpsuckers began to feed while they still had some yolk, primarily on small prey, including crustacean larvae and halacarid mites. After they completely absorbed their yolk, juveniles first fed largely on harpacticoids, but amphipods, isopods, and smaller juvenile lumpsuckers formed an increasing proportion of their diet as they grew. Behavioral selection of prey, rather than an increasing ability to ingest larger items, is suggested to be the basis for ontogenetic changes in diet.

Ultrastructural investigations of testes and spermiogenesis in two species of halacarid mites (Halacaridae, Actinedida, Actinotrichida): Thalassarachna basteri from the Baltic Sea and Halacarellus thomasi from McMurdo Sound (Antarctica)

Testes and sperm cells of two species of halacarid mites, Thalassarachna basteri from the Baltic Sea and Halacarellus thomasi from McMurdo Sound (Antarctica), were investigated. Testes are paired structures, composed of a glandular and a germinal part. The testicular lumen is filled with a very complex secretion that contributes to sperm cell aggregates. Early spermatids of T. basteri display unusual chromatin condensation within the nucleus, but the formation of an acrosomal complex with a small acrosomal vesicle and a long acrosomal filament can be regarded as typical for the group. Tubular invaginations of the plasmalemma occur at the cell periphery. A deep, ring-like infold divides the cell into one part containing the chromatin body and another containing mainly the invaginations and the acrosomal complex. The mature sperm cell is ovoid, aflagellate and surrounded by a distinct secretion sheath. In H. thomasi only a limited number of spermiogenesis stages were observable. Chromatin condensation was rather similar and peripheral invaginations also occurred. However, no acrosomal complex was observed in the early stages. The division of the mature sperm cells into two halves was even more pronounced in H. thomasi, since one half of the cell contained masses of convoluted structures. The same half also contained a structure that remotely resembled an acrosomal complex. The observed differences between T. basteri and H. thomasi sperms support the placing of the two halacarids in separate genera.

Halacarid mites (Acari: Halacaridae) as possible indicators of preferable culture beds of Japanese scallop Patinopecten yessoensis (Jay) (Pterioida: Pectinidae)

The relationship between the occurrence of arenicolous halacarid mites and Japanese scallop Patinopecten yessoensis (Jay) around Hokkaido, northern Japan was examined. A relatively high correlation was observed between the distribution of the main culture beds of the scallop and the occurrence of the mite genera Actacarus Schulz and Arenihalacarus Abé. These results suggest that these genera might be suitable indicators when searching for sites to establish new sowing culture beds of P. yessoensis (Jay).

Global distribution patterns of non‐halacarid marine intertidal mites: implications for their origins in marine habitats

AimWe investigated the taxonomic, ecological and global biogeographical trends of non‐halacarid marine mites with a view to understanding their origins in the marine environment. While halacarid mites are typically marine, numerous other mite taxa occupy littoral habitats, including rocky‐shores, boulder beaches, salt marshes and mangrove forest floors, and occur in most geographical regions.LocationThis study concerns the extant taxa of non‐halacarid marine mite from intertidal zones, worldwide.MethodsA literature survey was undertaken to compile the records for localities and habitats of all the known species of non‐halacarid intertidal mite. Simple analyses were used to determine their taxonomic and geographical trends. A multivariate analysis was used to compare how closely the biogeography of selected faunas conformed with the generally accepted marine biogeographical zones.ResultsAlthough the species records are incomplete because of variable sampling intensities among regions, there is clear indication that these marine mite faunas are species‐poor (only 162 species were recorded in the literature). The records for some groups (ameronothroid and hyadesiid mites), some habitats (rocky‐shores) and some world regions (Eastern Atlantic‐Boreal, Sub‐Antarctic and Southern New Zealand) are apparently representative of actual faunas, whereas those for the mesostigmatid and non‐halacarid prostigmatid mites, and mangrove and salt marsh habitats, are clearly incomplete. The faunas comprise mites from four suborders, the Mesostigmata, Prostigmata, Oribatida and Astigmata. Structuring of the lower taxonomic levels differs markedly among the suborders; mesostigmatid and prostigmatid mites comprise low species to genus and species to family ratios, relative to oribatid and astigmatid mites. These mite groups also differ with respect to ecological and geographical attributes; ameronothroid (oribatid) and hyadesiid (astigmatid) mites exhibit wider generic geographical distributions and stronger marine trophic links.ConclusionsThe emerging trends suggest different geological time‐scales for the evolutionary incursions into the marine environment by the mesostigmatid and prostigmatid mite group and the oribatid and astigmatid mite group. They suggest that members of the latter have had longer associations with marine intertidal systems. The origins of both groups are also likely to differ from those of the typically marine halacarid mites.

A new freshwater halacarid mite, genus Peregrinacarus (Halacaridae, Acari) from the Falklands

Peregrinacarus falklandensis n. sp., a halacarid mite from an East Falkland creek, is described and illustrated. This is the second Peregrinacarus species to date. The other species, P. reticulatus Bartsch, is recorded from Marion Island, Indian Ocean. The two species differ in chaetotaxy of the legs. The presence of halacarids in freshwater of southern polar and adjacent regions is discussed.

Halacaropsis praecognita n. sp. (Acari: Halacaridae) from southern Africa

The marine halacarid mite genus Halacaropsis Bartsch, 1996 (Acari: Halacaridae) currently comprises four species from the Mediterranean, northern Atlantic, and Australia. A new species, Halacaropsis praecognita n. sp. (Acari: Halacaridae), is described from the rocky shores of south-eastern Africa (Eastern Cape and KwaZulu-Natal). This species possesses the characteristic peg-like setae on leg I and enlarged median claws, but is distinguishable from the other Halacaropsis species by not having toothed median claws on any of the legs.

The Distribution of Halacaridae (Acari: Prostigmata) Among Macroalgae on Sheltered Rocky Shores

Clumps of macroalgae on sheltered shores exposed at low tide provide a mosaic of micro-habitats for halacarid mites. The predominant pattern is one of zonation, with the level of high water neap tides limiting the distribution of many species of Halacaridae. Within emersed clumps of macroalgae four micro-habitats are recognized: the dry surface layer of the clump; damp fronds within the clump retaining surface moisture; lower stipes and holdfasts; the surface of the substratum between the holdfasts. Halacaridae are spatially segregated, different species being associated with different micro-habitats within clumps. This has implications for the way in which intertidal phytal meiofaunal communities are sampled. In general damp fronds from within seaweed clumps are collected. Species characteristically associated with stipes, holdfasts and the substratum beneath the clumps are probably under-represented in the majority of collections, and may, therefore, be considered rare.

Halacarids (Halacaroidea, Acari) in freshwater. Multiple invasions from the Paleozoic onwards?

Halacarid mites are primarily marine, but about 60 species have specialized to live in freshwater. Invasion into continental waters has taken place independently in various epochs. The ancestors of the exclusively freshwater genera Lobohalacarus, Porohalacarus, Porolohmannella, Ropohalacarus, and those of the subfamily Limnohalacarinae, are supposed to have colonized the shores of Pangaea, become adapted to freshwater and dispersed via continental freshwater and coastal oligomixohaline waters in the Mesozoic. These exclusively freshwater genera are presumed to have existed for distinctly >100 million years. Many a species or species group is present world-wide. This pattern of distribution is thought to be due to a combination of Mesozoic (Pre-Mesozoic) age, euryvalence with respect to environmental factors, and predominantly parthenogenetic mode of reproduction. The history of Caspihalacarus and circum-Mediterranean limnic Copidognathus seems to be closely correlated with the fate of the Tethys and/or Paratethys; their speciation dating back to the Miocene-Pliocene. Though often found in groundwater, the majority of limnic halacarid species is not limited to this realm. Most of the halacarid genera presumably invaded continental waters via surface water habitats rich in interstices. Being generalists, and tolerating a wide range of environmental conditions, such as temperature, salinity, acidity, these halacarids can survive in both hypogean and epigean waters.

Lobohalacarus subterraneusn. sp., a freshwater halacarid (Acari: Halacaridae) from New Zealand

Abstract The freshwater halacarid mite Lobohalacarus subterraneus n. sp. is described. The genus Lobohalacarus is recorded from North and South America, Europe, Africa, Asia, and Australia, and all the species belong to a single natural group, the L. weberi group. L. subterraneus differs from members of the weberi group in its ornamentation of the dorsal plates, presence of subgenital setae, enlarged articular membranes, and reduced setation on the legs.

Marine mites (Halacaroidea: Acari): a geographical and ecological survey

Halacarid mites (Acari), with almost 700 species described, inhabit marine and freshwater habitats. The majority of genera are recorded from at least two ocean basins or continents. There is no evidence of endemic genera, in either littoral faunal provinces or in deep-sea regions. Copidognathus, a genus comprising 1/4 of all species described, is found in almost all geographic regions, depths and habitats. Other genera dominate or are restricted to cold waters, to warm waters or to distinct habitats.