Two heads are better than one: false head allows Calycopis cecrops (Lycaenidae) to escape predation by a Jumping Spider,Phidippus pulcherrimus (Salticidae)

The deflection of attack from vital organs to the wing margin is regarded as an important adaptation in hairstreak butterflies. However, this “lose-little-to-save-much” strategy akin to the detachable lizard's tail had never been tested experimentally. The present study tests the “false head” hypothesis by exposing a hairstreak butterfly, Calycopis cecrops, as well as many other Lepidoptera species as controls, to the attacks of the jumping spider, Phidippus pulcherrimus. The results unambiguously indicate that the “false head” is a very efficient strategy in deflecting attacks from the vital centres of the hairstreak butterfly whereas other similar-sized Lepidoptera fall easy prey. Predator fatigue resulting from unsuccessful attacks was also observed, suggesting that jumping spiders can learn to avoid attacking prey they cannot capture, which would increase the efficiency of the “false head” as a defensive mechanism.     

An eyespot that “blinks”: an open and shut case of eye mimicry in Eumorpha caterpillars (Lepidoptera: Sphingidae)

We describe the final instars of two tropical Sphingidae caterpillars – Eumorpha phorbas and Eumorpha labruscae – from Area de Conservacion Guanacaste, northwestern Costa Rica, whose anal horn has become a posterior eyespot structure capable of rapid palpitation. When approached or harassed, the caterpillars palpitate this eyespot and produce the effect of a blinking vertebrate eye. We propose that this “blinking” is an extension of eye mimicry or at least draws attention to the eyespot, functioning to startle or intimidate would-be predators. As snakes lack eyelids and do not blink, this suggests that the blinking eye represents a more generalized (or possibly mammalian) eye. Eyespot “blinking” is probably controlled by the same musculature used to wave the anal horn in earlier instars. The extent to which this eyespot is perceived as a blinking eye, and the degree of protection from the caterpillars’ suite of potential predators, remain to be discovered.     

Prey-holding abilities of the nests and webs of jumping spiders (Araneae,Salticidae)

Three characteristics of the silk devices of 12 species of Salticidae and three species of spiders from conventional web-building families (Dipluridae, Eresidae and Stiphidiidae) were investigated: macrostructure; prey-holding ability (measured by escape time for five types of insects); and the structure of the silk itself, as revealed by SEM. Five types of salticid nests were recognized, and a few salticids build webs. The webs of the eresid Stegodyphus mimosarum consist of thick structural threads and fine cribellate fibres. Disparity of thread diameter, although not as extreme, was observed in the webs and nests of the other species. In the webs and nests of all species, there were threads that merely rode one over the other without forming junctions and secure ‘naked’ junctions lacking accessory fibres and ‘sleeves’. Ensheathed junctions, which had ‘sleeves’, were found only in webs of Portia (Salticidae) and Cambridgea antipodiana (Amaurobiidae). The cribellate webs of Stegodyphus mimosarum (Eresidae) had greater prey-holding ability than any other webs or nests tested, but all webs and nests were capable of detaining insects at least briefly. The distinctions between spider webs and nests and between sticky and non-sticky webs are discussed.     

Two new species of Hymenoepimecis (Hymenoptera: Ichneumonidae: Pimplinae) with notes on their spider hosts and behaviour manipulation

The wasp genera included in the Polysphincta genus-group develop exclusively as koinobiont ectoparasitoids of spiders, an unusual pattern within Hymenoptera. All known species of Hymenoepimecis attack orb-web spiders and Hymenoepimecis argyraphaga was previously described inducing a sudden modification of its host's web-building behaviour. Information on parasitoid–host interactions and even on host identities for most members of the genus-group, however, remain scarce. In this study we describe two new species of Hymenoepimecis and present information on their hosts, spiders of the genera Leucauge (Tetragnathidae) and Manogea (Araneidae). Cocoon webs of both host species are distinct from their normal webs. The modified cocoon web of Leucauge roseosignata constructed under the influence of Hymenoepimecis japi sp. nov. is very similar to the cocoon web described for Leucauge argyra. It is composed of three axes, including several radial threads each, and a hub used by the larva to attach the cocoon's suspension line. Spiral viscous threads, present in normal webs and in webs of parasitized spiders carrying larvae in the initial instars, are absent in cocoon webs. In the cocoon web of Manogea porracea the horizontal sheet is poorly structured and the cocoon is attached far from the spider's normal resting position, in an area composed of a densely tangled structure.     

Nesting habits of the Japanese foliage spider,Cheiracanthium japonicum (Araneae: Miturgidae): host plant preference based on the physical traits of plant leaves

A Japanese foliage spider, Cheiracanthium japonicum, builds nests with plant leaves. The nests are classified into seven types in relation to the seasons and purposes of nesting. We investigated whether the spider selects a plant species according to the nest type and how the physical traits of leaves influence the spider's plant selection. The difference between the composition of the host plant species used for nesting and that of the seasonal vegetation cover was confirmed. This suggests that the spider chooses the host plant species regardless of its abundance in their habitat. Early juveniles use small living or large dead leaves of various plant species to build moulting nests. Females prefer long and large leaves found in Miscanthus sinensis and Phragmites japonica over other plant leaves to build breeding nests.     

Trolling for water striders: active searching for prey and the evolution of reduced webs in the spider Wendilgarda sp. (Araneae,Theridiosomatidae)

Wendilgarda sp. builds unusually simple webs attached to the surface of water. The simplest design consists of a single vertical line with sticky material near the bottom that is attached at the top to a single horizontal line and at the bottom to the water surface. The spider usually sits immobile waiting for prey as the sticky line skates erratically across the surface of the water, but some spiders actively dragged their webs back and forth across the water. The web's simplicity is apparently derived with respect to the webs of other Wendilgarda species, as spiders sometimes made more complex webs similar to typical Wendilgarda webs. The simplicity of W. sp. webs may be causally related to two other unusual traits: extreme variability in web design and construction behaviour and web manipulation behaviour; and construction of prey capture webs with sticky lines by mature males, confirmed here for the first time in a confirmed member of an orb-weaving family. Some behavioural innovations in Wendilgarda, such as the attachment of a short segment of non-sticky silk to the water surface just prior to laying each segment of sticky line, may represent blocks of behaviour that have been shifted temporally in the web construction sequence.     

Mating behaviour and maternal care in the tropical savanna funnel-web spider Aglaoctenus lagotis Holmberg (Araneae: Lycosidae)

Despite their abundance and diversity, Neotropical spiders have been the subject of relatively few studies of behavioural ecology. The sexual behaviour and maternal care of the spider Aglaoctenus lagotis (Lycosidae) is described here. We performed experimental manipulations to test the hypothesis that males are attracted by female cues in the web. Two predictions were tested: (a) webs used by a virgin female will attract more males than webs used by an inseminated female; (b) the main cue in the web is chemical, so webs recently used by virgin females will attract more males than those that are not recently used. Additionally, we tested the hypothesis that maternal care increases offspring survivorship. Results showed that males are attracted by recently used webs (z = 0.0015; p = 0.037; z-test) and webs of virgin females (z = 0.041; p = 0.036, z-test). Male sexual behaviour presented three different categories: court, pre-mate and mate. After the mating, the females built a cocoon that was transported adhered to the spinnerets and held by the last pair of legs. After the hatching of the eggs, the young migrated to the dorsal region of the mother's body for 5 days. During maternal care the mother eliminates a yellowish drop from its oral cavity, which is collected by the young. During the development of the young until adulthood, the offspring that have their mother present in the first stages of life have greater survival compared with those without maternal care. Our results make it possible to perform comparative analyses between a South American Lycosidae species and other species distributed worldwide.     

Microhabitat selection in the sand recluse spider (Sicarius thomisoides): the effect of rock size and temperature

In spiders, temperature is considered an important environmental variable for microhabitat selection. In this study, we evaluated the effect of temperature and rock size on the presence of the sand recluse spider Sicarius thomisoides and the degree of selectivity in different locations. This species is a large spider that lives under rocks in desert and semi-desert climates and is particularly active during the summer. In Chile, these spiders can be found at both coastal and inland locations under different thermal conditions, where usually the temperatures are lower near the coast. If large-scale climatic conditions are important for this species, they may be expected to select lower rock temperatures on the coast than at inland locations. In addition, we would expect that the spiders would choose larger rocks in inland compared to coast locations, which reduce the effect of high temperatures. We found that the probability of finding individuals of this species increased according to rock temperature and rock size in the field. Our results suggest that S. thomisoides prefers larger and warmer rocks to shelter under during the day, this selectivity being similar at both coastal and inland locations. Thus, this species tends to select rocks with the same thermal and structural conditions, independent of the climatic conditions.     

Morphometric and allozyme variation in the black-chinned tilapia Sarotherodon melanotheron (Perciformes,Cichlidae), with a revision of the subspecies complex

Based on morphometric and allozyme data of a large sample of black-chinned tilapia, Sarotherodon melanotheron, originating from over its entire geographical distribution range, the subspecific classification of this species has been revised. One subspecies, S. m. paludinosus, is synonymized with S. m. heudelotii. The validity of another subspecies, S. m. leonensis, is questioned. The remaining three subspecies, S. m. melanotheron, S. m. heudelotii and S. m. nigripinnis are clearly distinguished as separate taxa.     

Postembryonic development and population parameters of Alpaida veniliae (Araneae,Araneidae), reared in the laboratory

We studied the postembryonic development from hatching to the adult stage and determined population parameters of Alpaida veniliae. It is one of the most abundant species of the orb-weaving guild of the spider community of soybean crops in Buenos Aires province, Argentina. The first three instars occurred inside the egg sac, and instar IV (spiderlings) started the dispersion from it. The female of Alpaida veniliae achieved greater adult size and adult longevity than the male. Mean fecundity, mean number of egg sacs per female, mean number of eggs per egg sac, as well as the net reproductive rate, the intrinsic rate of increase (r), the generation time (T), and the reproductive values (V _x) of three cohorts were determined under laboratory conditions, indicating a high capacity for growth. Their biological and ecological attributes indicate the importance of conservation of this predator as a natural enemy of soybean crop pests.     

Morphological reply to a DNA call: a new cryptic species of Hydraena from western Europe,with a complete overview of the Hydraena gracilis complex (Coleoptera: Hydraenidae: “Haenydra” lineage)

Recent molecular analyses revealed unexpected genetic variability within Hydraena gracilis, one of the most common and widespread European moss beetles, belonging to the West Palaearctic endemic “Haenydra” lineage. For this taxon, molecular data univocally evidenced two distinct clades, the first one including populations from the Iberian Peninsula, and the second including populations from central and eastern Europe. Aedeagal morphology of H. gracilis was further investigated, finally demonstrating the actual existence of a new cryptic species of the H. gracilis complex in Portugal, Spain and the French Pyrenees. The geographical range of the true H. gracilis was consequently revised. Finally, dichotomous keys for males of all species belonging to the H. gracilis complex, and for males of all the Iberian “Haenydra” species, are also supplied.     

Population variation of web-invading spiders (Theridiidae: Argyrodes spp.) on host webs in Guam,Mariana Islands,Micronesia

Most Argyrodes spiders live in the webs of other spiders as kleptoparasites, stealing food from the host and scavenging small prey from the web. We observed three species of Argyrodes from the Micronesian island of Guam to learn (1) if Argyrodes species differ in their use of host-species webs, (2) whether some Argyrodes species occur more often in certain habitats, (3) whether population size of Argyrodes is a function of web size, and (4) how the presence of congeners affects population size on a web. Argyrodes lived most often in the large, long-lasting orb webs of Argiope appensa and Cyrtophora mollucensis, and, rarely, in the smaller, less durable orb webs of Neoscona spp. and Leucauge spp. Argyrodes argentatus and Argyrodes sp. A frequently co-occurred in Argiope webs, but A. argentatus was more common in beach strand and open disturbed habitats, while Argyrodes sp. A was more common in shaded native forest. The abundances of A. argentatus and Argyrodes sp. A in Argiope webs and the abundance of Argyrodes sp. B in Cyrtophora webs were positively correlated with the areas of the webs' prey-catching surfaces. The abundance of A. argentatus was inversely proportional to that of Argyrodes sp. A on Argiope webs and to that of Argyrodes sp. B on Cyrtophora webs, suggesting interspecific avoidance.     

Host selection by a kleptoparasitic spider

Argyrodes globosus (Keyserling, 1884) is a small kleptoparasite spider that steals prey from the web of web-building spiders. In coffee plantations in the south of Mexico it was observed to parasitize five species: Gasteracantha cancriformis (Linnaeus, 1785) and Verrucosa arenata (Walckenaer, 1841) (Araneidae), Leucauge mariana (Keyserling, 1881) and Leucauge venusta (Walckenaer, 1841) (morphologically indistinguishable species) and Leucauge argyra (White, 1841) (Tetragnathidae). G. cancriformis was more frequently parasitized than the other hosts. An analysis of web diameter for each host species indicated that for L. mariana/venusta, L. argyra and V. arenata the kleptoparasite was associated with webs of a certain size range (23-33cm diameter) although a far larger range of web sizes was available (17-50cm diameter). The average size of the web of G. cancriformis (~23cm) appeared to be close to the preferred size for the kleptoparasite and this, together with an apparent absence of host aggression, may explain the prevalence of A. globosus with this host. For the parasite, web size choice may involve a tradeoff among diverse factors including prey capture rate, ease of access to the web and aggressive behaviour by the host.     

Phytoseiidae from date palms in Israel with descriptions of two new taxa and a key to the species found on date palms worldwide (Acari: Mesostigmata)

The old world date mite Oligonychus afrasiaticus (McGregor) is an important spider mite pest of the date palms Phoenix dactylifera in most of North Africa and the Middle East. To identify potential predators of this key pest we monitored the phytoseiids in the date palm canopy and on the orchard floor for three consecutive years in the Southern Arava Valley of Israel. In this study we report on the phytoseiid species found. We describe two new species, Neoseiulus cozae and Typhlodromus shoshae, and redescribe seven species, Proprioseiopsis beatus, Neoseiulus marginatus, N. conterminus, N. rambami, N. bicaudus, Cydnoseius negevi and Typhlodromus athiasae, found on date palms or on the understorey Bermuda grass, Cynodon dactylon, gramineae in these orchards. A key to all species collected from date palm orchards worldwide is given. Proprioseiopsis beatus, N. marginatus and N. conterminus are recorded for the first time in Israel.     

Habitat,egg‐laying behaviour,eggs and tadpoles of four sympatric species of Pseudopaludicola (Anura,Leiuperidae)

In contrast to most leiuperid frogs, Pseudopaludicola falcipes does not lay eggs in foam nests; this could represent a reversion to the primitive state. We found that in four other Pseudopaludicola species, eggs were also not embedded in foam nests and had a well‐defined outermost jelly layer. The females also constantly moved or dived and males lacked vigorous “wiping/kicking” leg motions while eggs were being laid, features that make foam nesting difficult. The tadpoles of three species have two gaps in the marginal papillae along the lower labium and two posterior rows of labial teeth; the tadpoles of one species had three gaps and three rows, a pattern resembling that of some Physalaemus (Leiuperidae) species. Our data on tadpole morphology and reproductive behaviour do not allow us to rule out the paraphyletic nature of Physalaemus in relation to Pseudopaludicola but they provide some support against the “foam‐loss hypothesis” in Pseudopaludicola.     

A new polychaete genus and species of the Kongsfjorden,Spitsbergen, Svalbard

Glyphochaeta laudieni, a new genus and species of the “Spionidae”, is described from the Arctic. The specimens were collected from the Kongsfjorden, Spitsbergen, Svalbard, in a marine grotto. Glyphochaeta laudieni was associated with colonies of unidentified Bryozoa. This new genus and species is characterized by a prostomium with frontal horns, the absence of branchiae and sabre chaetae, and the presence of grooved spines which replace hooded hooks in some chaetigers of the middle body region. These spines are associated with glandular organs situated in neuropodia. The significance of characters for determining the systematic position of Glyphochaeta within “Spionidae” is discussed. Glyphochaeta laudieni is probably related to Pygospio elegans.     

Size,spines and crochets: defences of luna moth caterpillars against predation by brown anoles

Field-testing predator-prey interactions between invasive exotic brown anole lizards and sentinel larvae of the luna moth, Actias luna, suggests that late instars of this saturniid, and perhaps many other saturniids, are well defended by their spines and crochets against predation by lizards. However, Actias luna larvae remain vulnerable to anole predation until they reach about 3 cm in length. In contrast, even relatively small caterpillars that are chemically defended, such as those of the io moth, Automeris io, and the monarch butterfly, Danaus plexippus, were shown to be well defended against anoles by their toxins. There is an obvious advantage for caterpillars to be chemically defended. However, there is also a tradeoff: Danaus plexippus are restricted to feeding on a relatively small group of plants, which limits resources and requires specialisation; in polyphagous Automeris io, the constant production of elaborate spines and toxin leads to prolonged larval development, which is at least twice as long as that of Actias luna, and exposes the caterpillars to mortality factors such as parasitism for a longer duration.     

Orb‐web spiders (Araneae: Araneomorphae; Orbiculariae) captured by hunting‐wasps (Hymenoptera: Sphecidae) in an area of Atlantic Forest in south‐eastern Brazil

Members of two hunting‐wasp families, Pompilidae and Sphecidae, are among the major predators of orb‐web spiders. In this study, we collected paralysed spiders from natural nests and trap‐nests provisioned by sphecids in an area of Brazilian Atlantic Forest, and compared these data with the composition of species collected by visual searching during one year. Prey preferences were analysed based on the relative abundance of spider species, their size and web characteristics. We also compiled a list of orb‐weavers captured by four sphecid genera reported in 40 other studies. A large number of prey was obtained from natural nests of Trypoxylon (Trypargilum) albonigrum in Parque Estadual Intervales, especially species of Eustala, Parawixia, and Araneus (Araneidae). Other prey, stored in trap‐nests by T. lactitarse and unidentified hunting‐wasp species, included Nephila (Tetragnathidae), Parawixia, Ocrepeira, Mecynogea, Acacesia (Araneidae), and other spider species that were less abundant. All the species that were heavily preyed upon had a relatively lower abundance in our samples of prey availability. The range of body sizes of spiders captured by Trypoxylon in our study area include the size of some abundant orb‐weavers always absent in their nests. These results indicate that factors other than abundance in the field and the spider's size influence prey selection or susceptibility to attack.