Biodiversity and origin of the non-flying terrestrial arthropods of Henderson Island

Henderson Island, a raised coral island on the extreme south-easterly edge of the Indo-Pacific plate, is of great importance as one of the few examples of a Pacific island with intact lowland forest. It is also of biogeographic interest as it is practically the final island in a series of island chains, along which the fauna of Polynesia has colonized, reaching back to New Guinea. New collections of the non-flying terrestrial arthropod fauna were made on Henderson Island in 1991. In excess of 100 taxa are now known. There is a rich mite fauna (especially oribatids), with many apparently endemic, some 26 species of spider, and nine species of isopod (including three endemic to Henderson or nearby Ducie Atoll). In addition Diplopoda, Chilopoda, Amphipoda, Pseudoscorpiones, Diplura, Protura and Collembola are represented. The majority of the fauna is derived from the west, as expected, though many taxa appear to be introduced, some of them from the neotropics (e.g. Frigga crocuta and perhaps Hoplophorella stilifer).     

Thermal properties and fauna on the bark of trees in two different African ecosystems

Summary The thermal properties of 26 African tree species in two different ecosystems were studied using thermocouples. In a subtropical moist forest were three bark types of trees: species with thin and smooth bark types with low values of insulation across the bark; species with a more structured bark type and medium insulation values; and species with deep-fissured or scaly bark types and high insulation values. Only these latter trees are able to survive openings in the subtropical forest and stand alone on edges of forest gaps. In the savanna all tree species showed adaptations in the structure of their bark in different forms: many tree species shade their trunks. Some have low bark insulation and these are known to be sensitive to fires. Some tree species show high bark insulation and do not shade their trunks. Tree species with white bark avoid overheating of their surface by reflection of the radiation. The arthropod community living exclusively on the bark was investigated for the first time on South African trees, on ten tree species. In the two different ecosystems this habitat is occupied by different arthropod groups. In the subtropical forest Acari, Araneae, Opiliones, Isopoda, Myriopoda, Blattodea, Psocoptera, Heteroptera, Coleoptera, Formicidae, and Nematocera (Diptera) are the main arthropod groups living exclusively on the bark of trees. In the savanna Pseudoscorpiones, Araneae, Collembola, Blattodea, Psocoptera, Coleoptera, Neuroptera, Termites, Formicidae, Hymenoptera and Brachycera (Diptera) are the main arthropod groups living exclusively on the bark of trees. Within one ecosystem on one bark type the dominant species are similar; richly structured bark types have a richer fauna. In the forest, bark arthropod diversity is related to the bark structure of the constituent trees, and the arthropod communities on the bark would reflect changes in the structure of the forest. Forests comprising tree species with different bark types would have a richer total bark arthropod fauna. Specialists on richly structured bark types would die out if tree species composition were altered by man to give stands consisting only of tree species with smooth bark types. Bark arthropods in a subtropical moist forest have different proportions of herbivorous and fungivorous compared to carnivorous species than those on the bark of trees in a savanna.     

Importance of habitat structure to the arthropod food-web in Douglas-fir canopies

This study tested the hypothesis that habitat structure dictates the distribution and community composition of arboreal arthropods. A diverse arthropod assemblage of Douglas-fir canopies, which included Araneae, Psocoptera, Collembola and Homoptera, was chosen as a model system. Habitat structural diversity, defined as needle density and branching complexity of Douglas-fir branches, was manipulated in a four-month experiment by needle removal, thinning and tying of branches. Abundance of canopy spiders declined significantly following needle density reduction and branch thinning, branch tying significantly increased spider abundance. Distinct habitat utilization patterns were found among individual spider guilds. Orb weavers (Araneidae) dominated spider assemblages in structurally simple habitats, whereas tied branches were colonized primarily by sheet-web weavers (Linyphiidae) and nocturnal hunting spiders (Anyphaenidae and Clubionidae). Spider species richness and average body size of several spider species increased in structurally more complex habitats. Arboreal spiders appeared to be limited by strong bottom-up effects in the form of habitat quality and, to a lesser degree, prey availability. Habitat manipulations did not affect densities or biomass of flying arthropod colonists in the branch vicinity. Needle removal and branch thinning led to a significant decline in the abundance of Psocoptera and Collembola. Tying of branches resulted in an eight-fold increase in Collembola numbers, organisms most sensitive to habitat alterations. Canopy habitat structure modified vertical dispersal of Collembola from forest litter, which may have significant implications for arboreal consumers. Our results lend strong support to the importance of habitat structural diversity in explaining general patterns of arthropod abundance and diversity on plants.     

南充高坪机场土壤及草丛动物群落特征和鸟类的关系

机场鸟类是机场安全的重大隐患,减少机场附近鸟类数量是机场安全至关重要的一环.2007年4～12月,对南充高坪机场3种生境土壤动物和草丛动物群落组成、数量和季节性变化特征进行了初步的研究.调查共获得土壤动物25类,其中蜱螨目、原尾目、线虫纲为土壤动物群落优势类群,占年总捕获量的71.88%;常见类群有弹尾目、线蚓科、腹足纲、膜翅目、双翅目、鞘翅目、蚯蚓、蜘蛛目,直翅目9类,占总捕获量的22.84%.地表草丛动物21类,其中半翅目、蜘蛛目、双翅目、腹足纲为地表草丛动物的优势类群,占年捕获量的65.7%;常见类群有直翅目、鞘翅目、同翅目、膜翅目、鳞翅目、革翅目、弹尾目7类,占总捕获量的31.2%.将土壤动物群落、草丛动物群落与肉食性鸟类进行相关分析,结果显示土壤动物群落变化与肉食性鸟类群落之间有一定关系;草丛动物数量与肉食性数量鸟类呈现一定正相关性,机场肉食性鸟类数量与直翅目数量呈显著的正相关关系(r=0.910,P=0.032).结合机场区域鸟类食性观察、分析,直翅目、腹足纲动物是机场肉食性鸟类数量的主要捕食对象,通过定期割草、消除腐草和杂物、喷洒农药控制地表草丛动物是减少机场区域肉食性鸟类数量的有效方法和途径.     

Species richness and biogeography of non-acarine arachnids in Namibia

A total of 821 species, 296 genera, and 69 families of non-acarine arachnids (Araneae, Solifugae, Scorpiones, Pseudoscorpiones, Opiliones and Amblypygi) are presently known from Namibia. Patterns of spider, solifuge and scorpion species richness and endemism are summarized relative to the 14 major Namibian types of vegetation. Spiders are most speciose in the higher rainfall areas, solifuges in the dry areas, and scorpions in rocky areas. Namibia probably has the world's greatest diversity of solifuges. Many arachnids endemic to Namibia are associated with the Namib Desert sand dunes.     

ADDITIONAL NOTES ON SUBFOSSIL BIRD REMAINS FROM ASCENSION ISLAND

More extensive collections of subfossil bird bones from Ascension Island in the South Atlantic further confirm that the former seabird populations of the main island were composed of tropical species still present in greatly reduced numbers, mostly on offshore islets. A single specimen of Puffinus lherminieri provides the first fossil evidence of that species from the island. The extinct flightless rail Atlantisia elpenor was the only land bird certainly known to have been native. A femur, apparently from a vagrant individual, is referred to Porphyrula alleni , A specimen of Nycticorax , much smaller than any recent examples of N. nycticorax seen, is either from an unusually small vagrant or possibly indicates an undescribed endemic species.     

History and the species-area relationship in Lesser Antillean birds

We examined the species-area relationship for three historically distinct subsets of Lesser Antillean birds identified by molecular phylogenetic analysis of island and continental populations. The groups comprised recent colonists from continental or Greater Antillean source populations, old taxa having recently expanded distributions within the Lesser Antilles, and old endemic taxa lacking evidence of recent dispersal between islands. The number of young taxa was primarily related to distance from the source of colonists in South America. In a multiple regression, the logarithmic slope of the species-area relationship for this group was shallow (0.066+/-0.016). Old endemic taxa were restricted to islands with high elevation, and within this subset, species richness was related primarily to island area, with a steep slope (0.719+/-0.110). The number of recently spread endemic taxa was related primarily to island elevation, apparently reflecting the persistence of such populations on islands with large areas of forested and montane habitats. Historical analysis of the Lesser Antillean avifauna supports the dynamic concept of island biogeography of MacArthur and Wilson, rather than the more static view of David Lack, in that colonists exhibit dispersal limitation and extinction plays a role in shaping patterns of diversity. However, the avifauna of the Lesser Antilles is probably not in equilibrium at present, and the overall species-area relationship might reflect changing proportions of historically distinguishable subsets of species.     

Lichens of St Helena and Ascension Island

Lichens are the dominant organisms on most of the South Atlantic island of St Helena. In total, 220 different species were found during a recent survey, most of which have never been reported from the island. Previously, less than 50 lichen species were reported from the island, one half of which are most probably incorrect records. The total number of lichens known from the island now stands at 225. Most species could be identified, but the following, most probably endemic, species are described as new to science: Dolichocarpus seawardii , which is only the second species in this genus, the type being from Chile; Dermatiscum pusillum , which is only the third species in this African genus; Dimelaena triseptata ; Xanthoparmelia beccae ; and four Ramalina species, Ramalina geniculatella , R. ketner‐oostrae , R. rigidella , and R. sanctae‐helenae . The lichen flora has many species in common with that of the geologically much younger Ascension Island, where just under 100 species were recently found by the author, most of which are equally new to that island. Lecanora sanctae‐helenae, previously known as the only endemic lichen of St Helena, was also found to be abundant on Ascension Island. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 147–171.     

The importance of foundation species identity: A field experiment with lichens and their associated micro-arthropod communities

Foundation species provide habitat and modify the availability of resources to other species. In nature, multiple foundation species may occur in mixture, but little is known on how their interactions shape the community assembly of associated species. Lichens provide both structural habitat and resources to a variety of associated organisms and thereby serve as foundation species. In this study, we use mat-forming lichens and their associated micro-arthropods as a miniature ecosystem to study potential synergies between foundation species diversity and the abundance and functional diversity of higher trophic levels. We created lichen patches with monocultures and mixtures of up to four species, and extracted Collembola (identified to species level), Oribatida, Mesostigmata, Pseudoscorpiones, and Araneae with Tullgren apparatuses after 106 days of incubation within a natural lichen mat. We found that different lichen species supported different arthropod abundances. For 19 out of a total of 55 lichen mixtures and arthropod groups, we found non-additive, synergistic effects on arthropod abundance, although the specific lichen mixture causing synergistic effects differed with arthropod group. In addition, synergistic effects on arthropod abundance were more common for arthropod groups at lower trophic levels. The functional diversity of lichen mixtures explained patterns in Collembola abundance, but in the opposite direction than hypothesized because synergistic responses were more frequent in functionally similar lichen mixtures. Finally, we found few effects of lichen mixture identity or diversity on the functional diversity of Collembola communities. When applied to large-scale ecosystems, our results suggest that understanding interactions between coexisting foundation species and identifying those species that drive synergistic effects of foundation species on consumer biota, is likely to be of importance to biodiversity conservation and restoration efforts.     

The meaning of predatory specialization as illustrated by Aelurillus m-nigrum, an ant-eating jumping spider (Araneae: Salticidae) from Azerbaijan

The distinctions between a predator's diet, its prey-choice behaviour and its preference are illustrated in a study of Aelurillus m-nigrum Kulczyn'ski, a salticid spider from Azerbaijan. The natural diet of A. m-nigrum was determined from records of individuals feeding in the field (N=58). Ten arthropod orders were represented. Nine were from the class Insecta (Coleoptera, Collembola, Diptera, Heteroptera, Homoptera, Hymenoptera, Lepidoptera, Orthoptera, Psocoptera) and one from the class Arachnida (Araneae). Of 50 insects among the prey, 21 (42%) were Hymenoptera, with ants (family Formicidae) alone accounting for 31% of all prey records. Although the majority (69%) of the natural prey were not ants, results from prey-choice testing in the laboratory implied that A. m-nigrum preferred ants as prey. However, this preference was evident only when the testing environment included sand and a small stone. Our findings illustrate the importance of not conflating the concept of a predator's preference with the concept of a predator's natural diet and illustrate that physical features of a predator's habitat may be an important factor in influencing how strongly preference is expressed.     

微红梢斑螟蛀道节肢动物种群结构及生态位

选择我国江苏、安徽和广东7个不同林型的松树林地,对微红梢斑螟(Dioryctria rubella)蛀道节肢动物种群结构及生态位进行调查研究。结果表明:微红梢斑螟蛀道节肢动物种群隶属2纲9目13科,分别为蛛形纲蜘蛛目、蜱螨目,昆虫纲弹尾目、革翅目、啮虫目、半翅目、缨翅目、鞘翅目、膜翅目;利用相对优势指标判别微红梢斑螟蛀道节肢动物优势种有螨科和隐翅虫科,丰盛种有跳虫科,常见种有啮虫科、蠼螋科、蚁科、锯谷盗科、象甲科、蓟马科和茧蜂科,偶见种有小蠹科、蝽科和微蛛科;利用Levins生态位宽度和Pianka生态位重叠对各种群生态位计算表明,隐翅虫科与微红梢斑螟的时间和空间生态位重叠值最大,说明在各种群中隐翅虫科与微红梢斑螟的跟随关系最为紧密;利用聚集度指标法判别优势种群隐翅虫的空间分布属于聚集型分布,用零频率方法计算隐翅虫种群的空间格局为聚集型,种群类型为聚集度逆零频率制约型。     

The shore fishes of Ascension Island

Seventy-one species of shore fishes are recorded from Ascension in a checklist which includes notes on ecology and behaviour. The extraordinary abundance of blackfish, Melichlhys niger , and the aggressive nature of moray eels, Lycodontis moringa , towards man are briefly mentioned. The number of species recorded is low for a tropical island and seems to reflect Ascension's geographical isolation and lack of habitat diversity; 15·7% of Ascension shore fishes (excluding one fish not identified to species level) appear to be endemic to the island, with a further 17·1% known only from Ascension and St Helena; 30·0% are recorded only from the western and central Atlantic, while 7·1% are recorded from the eastern and central Atlantic; 30·0% are widespread Atlantic species. Two new species are described: Taenioconger camelopardalis and Helcogramma ascensionis.     

Effects of<Emphasis Type="Italic"> Formica</Emphasis> ants on soil fauna-results from a short-term exclusion and a long-term natural experiment

Wood ants (Formica spp.) were hypothesised to affect the composition and greatly reduce the abundance of large-sized soil fauna by predation. This was tested in two ways. Firstly, a 4-year-long experimental study was carried out in a mixed forest. Five ant-free 1.3-m(2) plots were created by fenced exclosures within an ant territory. Five nearby plots had fences with entrances for the ants. In addition, five non-fenced control plots were selected. Soil fauna (e.g. Coleoptera, Diptera larvae, Collembola and Araneae) was sampled during the summers of 1997-2000. The soil fauna was affected by the exclosures but there was no detectable effect of ants on the soil fauna. Secondly, soil fauna was studied within a large-scale natural experiment in which the long-term (30 years) effects of red wood ants could be assessed inside and outside ant territories. This long-term natural experiment revealed no significant effects of ants on the abundance or composition of soil fauna. The results from the two studies indicate that the effects of wood ants on soil fauna are fairly small. The hypothesis that wood ants are key-stone predators on soil fauna could, thus, not be supported.     

The genus Erechthias Meyrick of Ascension Island,including discovery of a new brachypterous species (Lepidoptera,Tineidae)

One previously named and two new species of the tineid genus Erechthias Meyrick are described and illustrated from the small, remote, mid-Atlantic Ascension Island. With these additions the Lepidoptera fauna of Ascension now totals 38 known species. Little is known regarding the biology of the two new species of Erechthias, and none of the species has been reared from larvae from Ascension. Erechthias minuscula (Walsingham) is a widespread, largely pantropical species first described from the West Indies. Larvae of Erechthias minuscula are known to be scavengers on a wide variety of dead plant material. Erechthias ascensionae,new species, is one of two species of Erechthias now known to be endemic to the island. The other endemic species, Erechthias grayi, new species, is further remarkable in having wing reduction occurring in both sexes. It is one of the few species of Lepidoptera known where this extreme of brachyptery involving both sexes has evolved. The larvae of Erechthias grayi are believed to be lichenivorous, and larval cases suspected to represent this species are illustrated.     

Genetic variability in migratory and endemic island songbirds (genus Vireo): A comparative assessment using molecular and morphological traits

Low genetic variation is thought to increase the risk of extinction in island species; however, these species can differ both in terms of endemism and gene flow. In a previous study, the endemic species of Puerto Rico (V. latimeri) and Jamaica (V. modestus and V. osburni) were shown to have less genetic variability than a continental relative, V. griseus. In this study, a migratory island species, V. altiloquus, is analyzed together with the endemics in order to (1) compare levels of genetic variation in migratory and endemic island species, and (2) assess this variation using both molecular markers and morphological traits. Each island species is also compared to a continental relative (V. griseus for the endemic species, and V. olivaceus for the migratory species). Variability in random amplified polymorphic DNA markers was significantly lower in the endemic species than in either migratory population. All island populations had significantly lower levels of variation than their respective continental relatives, but with significantly greater reduction in the endemic species. In contrast, the morphological measures revealed only two cases with a significantly lower CV in an endemic species compared to V. altiloquus or V. griseus. All others exhibited either no differences in CV or greater levels in the island populations. While the molecular results generally correspond to predictions of lower variability in endemic vs. migratory island species and island vs. continental species, the morphological comparisons do not, and therefore may not be useful for quick, field-based assessments of underlying genetic variability. This revised version was published online in July 2006 with corrections to the Cover Date.     

Arthropod community associated with the canopy of Attalea phalerata Mart. (Arecaceae) during the flood period of the Pantanal of Poconé, Mato Grosso, Brazil

Six trees of the palm species Attalea phalerata Mart. were sampled during high water (aquatic phase) of the Pantanal of Mato Grosso (February 2001), by canopy fogging. The composition, structure, and biomass of the arthropod community associated with their canopies were analysed, as well as the influence the flood pulse renders on it. Each tree was fogged once, followed by three consecutive collections. A total of 63,657 arthropods (643.0 +/-; 259.87 ind./m(2)) were collected, representing 25 orders in the classes Insecta, Arachnida, Diplopoda and Crustacea. The dominant groups were Acari (40.0%; 257.2 +/- 116.50 ind./m(2)), Coleoptera (12.0%; 77.5 +/- 64.93 ind./m(2)), Psocoptera (9.2%; 59.0 +/- 38.00 ind./m(2)), Diptera (8.4%; 54.1 +/- 18.72 ind./m(2)), Collembola (8.3%; 53.4 +/- 26.24 ind./m(2)) and Hymenoptera (7.9%; 50.6 +/- 21.40 ind./m(2)), the latter mostly represented by Formicidae (49.2%). Arthropod biomass amounted to 8.86 g dry weight and 0.18 mg/m(2). Coleoptera, Blattodea, Orthoptera, Araneae and Hymenoptera were the most representative taxa. The hydrological regime (flood pulse), as well as seasonality, appear to strongly affect the composition and structure of this canopy community.     

Foraging ecology in the lizard Anolis oculatus (Iguanidae) from Dominica, West Indies

In general, populations of Anolis lizards on West Indian islands face few predators, are at high density and are thought to be limited by food. This paper describes how the foraging ecology of Anolis oculatus , a solitary species confined to the island of Dominica, Lesser Antilles, varies with habitat and season in relation to the quantity and quality of available food.
Availability of invertebrate food (determined using pitfall traps and sticky traps) was greater in a dry scrub woodland site, Cabrits National Park (CNP), compared with a montane rainforest site, Palmiste Ridge. In the former, there were general increases in abundance, volumes of softbodied prey and sizes of invertebrates from dry season to wet season. Concomitant dietary changes, as determined principally by stomach flushing, included an increase (by volume) in the proportion of soft-bodied prey. Dietary analyses confirmed the importance of ants (Formicidae) in the diet of A. oculatus , although for large individuals (mainly adult males) at the rainforest site, soft-bodied prey such as Oligochaeta and Orthoptera were, in volumetric terms, more important. Prey capture observations showed that large A. oculatus fed mainly above ground. Anolis oculatus at the montane rainforest site used higher perch heights than those in dry scrub woodland, although in both habitats, small individuals (mainly juveniles) fed mainly at ground level on ants. In the dry season in CNP, the diet (in volumetric terms) of smaller Anolis was dominated by hardbodied prey such as ants, springtails (Collembola), barklice (Psocoptera) and beetles (Coleoptera). large Anolis used springtails and barklice to a lesser extent, resulting in relatively low food niche overlap values between size classes and a reduced potential for intraspecific competition compared with the wet season.     

The bark and ambrosia beetles (Curculionidae, Scolytinae) of Cocos Island, Costa Rica and the role of mating systems in island zoogeography

Cocos Island is a small oceanic island midway between Costa Rica and the Galápagos Archipelago; about 2 Myr in age, it is the only tropical oceanic island in the eastern Pacific with tropical wet forest. We identified several hundred bark beetle specimens collected during recent expeditions by INBio, the National Biodiversity Institute of Costa Rica, and re-examined all specimens from earlier collections. We report 19 species in ten genera, seven or eight of which are endemic, making scolytines the largest group of beetles known from the island. We describe as new Pycnarthrum pseudoinsulare , Xyleborinus cocoensis , and Xyleborus sparsegranulosus , resurrect Xyleborus bispinatus as separate from X. ferrugineus , and report six other species as new to Cocos Island. Three-quarters of the scolytines reproduce by brother–sister mating, and we argue that inbreeders are superior island colonists because they are less affected than are outbreeders by problems of mate location and inbreeding depression. The fauna and flora of Cocos Island arrived by dispersal and human transport. We examine natural colonization patterns for the fauna, using the distributions of the relatives of island endemics: most colonization came from the Americas, but the closest relatives to some endemics are found on Caribbean or Galápagos islands. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 89 , 729–743.     

Aquatic insects of cross-border water currents between Belarus and Ukraine

224 species of aquatic insects from 9 orders were found in cross-border water currents between Belarus and Ukraine: Collembola—4, Plecoptera—3, Ephemeroptera—25, Odonata—33, Trichoptera—47, Megaloptera—1, Heteroptera—19, Coleoptera—88, Lepidoptera—4 species. The fauna of aquatic insects is rich and includes a number of species rare in Belarus and Europe.     

西双版纳热带雨林环境变化对蝗虫区系成分和物种多样性的影响

西双版纳地区已经记录蝗总科6科48属79种。其中86.1%的种类是东洋区成分,包括22个特有种,其余13.9%为广布种。随着雨林的垦伐和生境的变化,物种成分正在发生明显的变化。不仅物种数量逐渐下降,而且东洋区物种成分减少,广布种成分增加,特有的物种也因生境的单调化而减少甚至消失。多样性指数和均匀度指数沿着雨林—灌丛—农田—橡胶林生境梯度的变化呈显著下降的趋势。龙山部分地保持了雨林生境的特征,但是对保持蝗虫物种多样性方面的作用很有限。