Geographical and ecological distribution of marine halacarid genera and species (Acari: Halacaridae)

At the end of 2002, the number of marine halacarid species was 1018, that of genera 51. A single genus, Copidognathus contains 33% of all species (336). Eleven genera are monotypic. Geographical provinces with a large number of species are the tropical western Pacific, temperate northeastern Atlantic, temperate southeastern Pacific, and Mediterranean-Black Sea. Most records of halacarid species are from temperate and tropical areas; 10% of species are known from polar zones. On a generic level, 29 genera are recorded from tropical and temperate but not from polar provinces, five genera are restricted to the tropics, and none to polar regions. The majority (920 species or 90%) of all species live in the upper 200 m. Records of genera with exclusively algivorous or brackish/fresh water species are bound to littoral habitats; all the other genera occur in more than one depth zone. Arenicolous genera, though most abundant in the littoral zone, have representatives in the bathyal. Four marine genera (Copidognathus, Halacarellus, Isobactrus, Lohmannella) have representatives in coastal fresh water, and three genera, Acarothrix, Caspihalacarus and Peregrinacarus, are predominantly inhabitants of diluted brackish and fresh water. None of the free-living halacarid genera of the world's oceans appears to be endemic to one geographical province.     

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. Guest editors: E. V. Balian, C. Lévêque, H. Segers & K. Martens Freshwater Animal Diversity Assessment     

Simognathus coreensis, a new halacarid mite (Halacaridae: Acari) from Korea

Simognathus coreensis n. sp. is described on the basis of the specimens collected from Youngdeok, the east coast of South Korea. This is the first record of this genus from Korea. Diagnostic features are as follows: big cornea present on ocular plate, covering major portion of it; lateral claws II–IV with accessory process which contain about 5 minute (meaning `very small') teeth, and lateral claws smooth ventrally; prominent foveae on all telofemora; anterodorsal and posterodorsal plate subequal; lateral side of anterior epimeral plate foveate. This species is similar to S. corneatus Otto and S. exoticus Otto. Dissimilarities are discussed. Abbreviations: AD, anterodorsal plate; AE, anterior epimeral plate; ds, dorsal setae of idiosoma I; GA, genitoanal plate; GO, genital opening; PE, posterior epimeral plate; EP I, epimeral process I; PGS, perigenital setae; P1-P3, first to third palpal segment; SGS, subgenital seta.     

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.     

New species of Halacaridae (Acari) from New Zealand

Abstract

Seven new taxa of marine mites (Halacaridae) are described from the marine littoral zone of northern and southern New Zealand: Agauopsis novaezelandiae, A. luxtoni, Halacarellus lubricus, Copidognathus lubricus, Simognathus glaber, S. glareus, and Rhombognathus novaezelandicus. A list of halacarid species known from New Zealand waters is added.     

A hydrothermal vent mite (Halacaridae,Acari) with a new Corynophrya species (Suctoria,Ciliophora), description of the suctorian and its distribution on the halacarid mite

Copidognathus nautilei Bartsch, 1997, from a hydrothermal vent field of the Mid-Atlantic Ridge at about 13°N, 45°W and 4090 m depth, was infested with the suctorian Corynophrya abyssalis n. sp., with up to 58 epizoans per mite. The new suctorian has a sacciform body with seven longitudinal ribs, a compact macronucleus and up to 40 non-retractile tentacles. The budding is exogenous. The systematic position of the new species and the genus Corynophrya is discussed, as well as infestation rates and sites of suctorians on their halacarid hosts.     

Phylogenetic taxonomy of the marine mite genus Rhombognathides (Acari: Halacaridae: Rhombognathinae)

This study examined the impacts of the alien waterweed, water hyacinth, on the abundance and diversity of aquatic macroinvertebrates in the littoral areas of northern Lake Victoria in Uganda. The weed had undergone explosive growth on the lake causing serious disruption to people, the economy and the ecosystem. This study was confined to impact of the weed in the littoral zone, not to the large floating mats of vegetation which float across the lake and clog large areas of shoreline.The littoral area studied comprised of fringing mats of Eichhornia crassipes (Mart) Solms (water hyacinth) to the lakeward of Cyperus papyrus; water hyacinth mats undergoing colonisation by Vossia cuspidata (Roxb.) Griff.; and a typical Cyperus papyrus L shore with no outer floating mat of water hyacinth. Numerical abundance (Nos. m^–2) and diversity (No. of taxa) of macroinvertebrates recovered from pure Eichhornia crassipes and the Eichhornia-Vossia succession increased from the fringe of the Cyperus papyrus towards the open water. In the typical Cyperus papyrus fringe, in the absence of water hyacinth, abundance was highest at the papyrus/open water interface and dropped off sharply towards open water. The Shannon–Weaver diversity index (H) of macroinvertebrates decreased progressively from pure Eichhornia crassipes stands, to Vossia/Eichhornia beds and Cyperus papyrus stands (H=0.56, 0.54 and 0.34, respectively) but were not significantly different. Dissolved oxygen decreased from open water into vegetation where it approached anoxia. Water hyacinth appeared to enhance the abundance and diversity of aquatic macroinvertebrates at the interface with the open water. The impoverished abundance and diversity of the macroinvertebrates deeper into the vegetation mats suggested negative environmental impacts of the water hyacinth when the fringe is too wide. Further research is recommended to establish the optimum width of the fringe of stationery water hyacinth that promotes maximum abundance and diversity of aquatic macroinvertebrates and, possibly, of other aquatic life. Since this study in 1997, there has been a dramatic decrease in Eichhornia infestations and by June 2000 it appeared largely to exist only as fringing vegetation in bays and inlets.     

A new species of the `Copidognathus tricorneatus' group (Acari: Halacaridae) from India

A new species of the Copidognatus tricorneatus group, C. andhraensis is described on the basis of the specimens collected among the phytal samples from Visakhapatnam, India (Bay of Bengal). Similarities and dissimilarities with the related species are discussed. This is the first record of C. tricorneatus group from India.     

A new species of Limnohalacarus (Acari: Halacaridae) from a crater lake in Java

A new species of halacarid mite of the genus Limnohalacarus is described from Ranu Lamongan in East Java.     

Peregrinacarus reticulatus gen. nov. spec. nov., a freshwater halacarid mite (Acari,Halacaridae) from Marion Island

Peregrinacarus reticulatus gen. nov. spec. nov. is described. The genus belongs to the subfamily Halacarinae and is related to the marine genus Halacarellus. The most marked character is the absence of a ventromedial seta on tarsus I. P. reticulatus supposedly is a very recent immigrant in diluted brackish and fresh water. This revised version was published online in July 2006 with corrections to the Cover Date.     

The vertical distribution of the British intertidal Acari—the non halacarid fauna (Arachnida: Acari)

The vertical distribution of the non halacarid littoral Acari on rocky shores was examined. The habitat of these Acari was investigated and compared with that of the Halacaridae. Some physiological factors were investigated to explain this distribution. Three ecologically distinct life styles were recognized among these Acari.     

Halacaridae (Acari) from Pujada Bay (the Philippines): description and biogeography of three new and two known species

Three new and two known Halacaridae species belonging to the genus Copidognathus collected among seagrass plants in Pujada Bay (Mindanao, the Philippines) are described. Copidognathus ivanomorsellii sp.n. belongs to the `Copidognathus gibbus' group and shows the main characteristics of the group but differs from known species as the two triangular porose areolae on AD are joined together, the typical shape of the lateral line of the costae of PD, the distance between the anterior gland pore on PD and the lateral margin of PD, tarsi III and IV with 4:4 dorsal setae, ventral seta on trochanter III almost as long as ventral seta of basifemur III, anterior end of AD with rosette pores, AE and GA only laterally fused but separated in the middle portion and elongated frontal spine (projection) on AD, lateral claws with very fine pecten ventrally. A zoogeographical distribution of the `C. gibbus' group is reported. Copidognathus pujadus sp.n. belongs to the `Copidognathus bairdi' group and is loosely related to C. sideus Bartsch, 1982, C. sidellus Bartsch, 1985 and C. euryalus Bartsch, 1997b. Differences were observed and are discussed. Copidognathus philippinensis sp.n. belongs to the `Copidognathus curassaviensis' group but differs from the four known species within the group by the elevated ridge below the middle two areolae on AD area which connects the two areolae. In addition, two known species i.e. Copidognathus uniscutatus Bartsch, 1984, C. faubeli Bartsch, 1986 were collected. The Halacaridae fauna recorded so far from the Philippines is summarised and discussed.     

Diversity, distribution and ecology of water mites (Acari: Hydrachnidia and Halacaridae) in high Alpine lakes (Central Alps, Italy)

Information on water mite assemblages from high elevation lentic biotopes is scant. A survey of 14 small Alpine lakes located between1900 and 2400 m a.s.l. in Italy resulted in the discovery of 17 species of Hydrachnidia and a single species of freshwater Halacaridae. Arrenurus conicus and Lebertia tuberosa were the most widespread and abundant species; Lebertia sefvei, Lebertia rufipes, Oxus setosus, Panisus torrenticolus and Sperchon glandulosus were also widely distributed but relatively less abundant. Atractides fissus and Arrenurus conicus are recorded for the first time from Italy. In contrast to mid/low elevation lakes and ponds, water mite assemblages of alpine lakes are less diverse and are composed mainly of rheo- and crenobiontic taxa, most of which are cold-stenothermic. Typical standing water dwellers represented only a small fraction (23%) of the species sampled. A principal component analysis conducted on lake environmental variables resulted in a clear separation of the lakes mainly based on ionic contents, pH and temperature. Water mites seem to be less influenced by these factors than by temperature fluctuations and habitat stability and heterogeneity. We conclude with some considerations of the influence of abiotic and biotic factors on the altitudinal and latitudinal distribution pattern of water mites.     

The occurrence of Limnohalacarus (Acari: Halacaridae) in Lake No,White Nile

Limnohalacarus africanus and L. fontinalis are recorded from Lake No. These are respectively the third and second records of these species, and represent considerable extensions of their known ranges.     

Diversity, distribution and ecology of water mites (Acari: Hydrachnidia and Halacaridae) in high Alpine lakes (Central Alps, Italy)

Information on water mite assemblages from high elevation lentic biotopes is scant. A survey of 14 small Alpine lakes located between 1900 and 2400 m a.s.l. in Italy resulted in the discovery of 17 species of Hydrachnidia and a single species of freshwater Halacaridae. Arrenurus conicus and Lebertia tuberosa were the most widespread and abundant species; Lebertia sefvei, Lebertia rufipes, Oxus setosus, Panisus torrenticolus and Sperchon glandulosus were also widely distributed but relatively less abundant. Atractides fissus and Arrenurus conicus are recorded for the first time from Italy. In contrast to mid/low elevation lakes and ponds, water mite assemblages of alpine lakes are less diverse and are composed mainly of rheo- and crenobiontic taxa, most of which are cold-stenothermic. Typical standing water dwellers represented only a small fraction (23%) of the species sampled. A principal component analysis conducted on lake environmental variables resulted in a clear separation of the lakes mainly based on ionic contents, pH and temperature. Water mites seem to be less influenced by these factors than by temperature fluctuations and habitat stability and heterogeneity. We conclude with some considerations of the influence of abiotic and biotic factors on the altitudinal and latitudinal distribution pattern of water mites.     

Ticks (Acari: Ixodoidea) in China: Geographical distribution,host diversity,and specificity

Ticks are obligate blood‐sucking ectoparasites, which not only directly damage through bites but also transmit many pathogens. China has a high diversity of tick species, 125 species have been reported, including 111 hard tick and 14 soft tick species. Many of the ticks are important vectors of pathogens, resulting in zoonoses. The dynamics of ticks are affected by both the host and habitat environment. However, systematic studies on the geographical distribution, host diversity, and specificity of ticks are limited in China. To achieve this goal, the relevant available data were summarized and analyzed in this study. Ticks are distributed in all parts of China and Xinjiang has the most records of ticks. The distribution of ticks in adjacent areas is similar, indicating that the habitat environment affects their distribution. Most ticks are widely distributed, whereas some species are endemic to their distributed regions. Ticks are parasitic on mammals, birds, and reptiles, of which mammals are the main host species. Overall, most ticks parasitize different hosts, only a few ticks have strict host specificity, such as ticks that are specifically parasitic on reptiles and bats. In addition, environmental changes and control efforts also influence the dynamics of ticks. These results can better reveal tick biological traits and are valuable for tick control.     

Geographical distribution of wildLactuca species (Asteraceae, Lactuceae)

A broad survey of available world literature showed that at least 98 wildLactuca spp. (Asteraceae) have been described taxonomically. The distribution of the genusLactuca worldwide includes 17 species in Europe, 51 in Asia, 43 in Africa, and 12 in the Americas (mostly the North American subcontinent). Species originating in Asia, Africa, and the Americas form ca. 83% of knownLactuca spp. richness; however, they are very poorly documented from the viewpoint of taxonomic relationships, ecogeography, and variability. The phytogeography ofLactuca spp. regarding their distribution on different continents and in relation to the structure of the lettuce gene pool is discussed. A more detailed analysis of geographical distribution and habitats is given for some species (L. serriola, L. saligna, L. virosa, L. perennis, L. quercina, L. tatarica), which represent the primary, secondary, and tertiary gene pools of cultivated lettuce (L. sativa). Original and synanthropic distributions ofLactuca spp. and their occurrence in natural and secondary habitats are discussed, along with the representation of wildLactuca spp. in world gene-bank collections. Global biodiversity ofLactuca spp. and their representation in germplasm collections are poorly documented. Future studies of taxonomy, phytogeography, ecology, phylogenetic relationships, and genetic diversity are needed for a more complete understanding of this genus and taxonomically related genera.     

Geographical variation in the species Montivagum dihumerale and speciation in chigger mites (Acari: Trombiculidae)

Intraspecific morphological variation of the chigger mite species Montivagum dihumerale (Traub et Nadchatram, 1967) is studied. Eco-geographic rules of the variation are revealed. General size of mites is found to be increased along with the rise of the high-mountain character of the landscape in the collection localities. The numbers of idiosomal setae are varied independently from the size parameters and geographically close populations are proved to be the most similar by these characters. At the same time, numbers of the setae of different types play the leading role in the discrimination of closely related Montivagum species, while the eco-geographical rules have not been found in this genus at the level of interspecific differences. As a result, the hypothesis is set up, that a significant degree of isolation of local populations separated from each other by high mountain ranges of the Central Asia is the main factor of speciation in the genus Montivagum. Regional character of this speciation mode is confirmed by the comparison with other chigger mites taxa.