Comparative cytogenetics in different populations of the cavernicolous diplopod Pseudonannolene strinatii (Diplopoda, Pseudonannolenidae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Description of a new species and the karyotype of the cavernicolous millipede Pseudonannolene Silvestri and the karyotype of Pseudonannolene strinatti Mauriès (Diplopoda, Pseudonannolenida, Pseudonannolenidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Costs and benefits of freezing behaviour in the harvestman Eumesosoma roeweri (Arachnida, Opiliones)

Animals present an enormous variety of behavioural defensive mechanisms, which increase their survival, but often at a cost. Several animal taxa reduce their chances of being detected and/or recognized as prey items by freezing (remaining completely motionless) in the presence of a predator. We studied costs and benefits of freezing in immature Eumesosoma roeweri (Opiliones, Sclerosomatidae). Preliminary observations showed that these individuals often freeze in the presence of the syntopic predatory spider Schizocosa ocreata (Araneae, Lycosidae). We verified that harvestmen paired with predators spent more time freezing than when alone or when paired with a conspecific. Then. we determined that predator chemical cues alone did not elicit freezing behaviour. Next, we examined predator behaviour towards moving/non-moving prey and found that spiders attacked moving prey significantly more, suggesting an advantage of freezing in the presence of a predator. Finally, as measure of the foraging costs of freezing, we found that individuals paired with a predator for 2 h gained significantly less weight than individuals paired with a conspecific or left alone. Taken together, our results suggest that freezing may protect E. roeweri harvestmen from predatory attacks by wolf spiders, but at the cost of reduced food and/or water intake. (C) 2009 Elsevier B.V. All rights reserved.

Sexual Differences in the Behavior of the Harvestman Leiobunum vittatum (Opiliones, Sclerosomatidae) Towards Conspecific Cues

Preliminary observations of the harvestman Leiobunum vittatum found that individuals rub their bodies against the substrate, presenting the possibility of chemical marking. To determine whether or not L. vittatum individuals can detect substrate-borne chemical cues, we compared responses of L. vittatum males and females to substrate-borne male and female cues. We found that individuals of L. vittatum do respond to conspecific cues and that their responses are sex-specific. In response to substrate-borne conspecific cues, male L. vittatum spent more time, engaged in more scraping with their sensory legs I, and engaged in pedipalpal tapping more often in the presence versus absence of conspecific cues (male and female equally). Furthermore, in the presence of conspecific cues, males engaged in two behaviors never observed in females-(a) "fast approach" and (b) "jerking", the latter of which was never observed in the presence of cricket cues. In contrast to males, females did not spend more time on conspecific cues, but did spend more time tapping their pedipalps in the presence of male vs female cues, suggesting an ability to distinguish between them. A final experiment explored the possibility that females could discriminate among males of varying histories of agonistic interactions based upon their chemical cues. We found no support for this hypothesis. Our results demonstrate that L. vitattum do respond to conspecific cues, and introduce the possibility that intraspecific communication may be mediated in part by chemical cues.

Maternal care in the Neotropical harvestman Liogonyleptoides tetracanthus (Opiliones: Gonyleptidae)

We describe post-ovipositional maternal care in Liogonyleptoides tetracanthus Mello-Leitao 1932 (Gonyleptinae) and experimentally evaluate the protective role of this behavior against egg predation under laboratory conditions. Females laid 138.8 eggs on average and remained close to the clutch during the entire day. Eggs hatched after 11-15 days and nymphs dispersed from maternal protection after one to two days. Most of the experimental clutches left unattended were entirely consumed by conspecifics in 2-3 days. There was no reduction in egg number in the clutches protected by females. Although biological data are scarce, there are cases of egg hiding, paternal and maternal care within the subfamily Gonyleptinae. This diversity of forms of parental care is unusual when compared to other gonyleptid subfamilies, and future systematic revisions of the polyphyletic Gonyleptinae should include parental care as a potential source of phylogenetic information.

Revision of Nanophareus, a mysterious harvestman genus from Chile, with descriptions of three new species (Opiliones: Laniatores: Gonyleptidae)

The Chilean genus Nanophareus Roewer, 1929 is revised and three new species are described: N. araucanus sp. nov. (type locality: Parque Nacional La Campana, Valparaiso, Chile); N. bipartitus sp. nov. (type locality: Parque Nacional La Campana, Valparaiso, Chile); N. bosqenublado sp. nov. (type locality: Parque Nacional Fray Jorge, Coquimbo, Chile). The type species, N. palpalis Roewer, 1929, is redescribed and a lectotype is designated. A cladistic analysis was performed using these three new species plus N. palpalis and 14 more laniatorid species, and a data matrix of 72 characters: Seven from the ocularium, 22 from the dorsal scutum, one from the venter, one from the chelicera, eight from the pedipalp, 24 from male legs, and nine from male genitalia. Two equally most parsimonious trees were found (L = 210; C.I. = 0.41; R.I. = 0.51). Nanophareus was recovered as nested within a paraphyletic subfamily Pachylinae. The genus Nanophareus was found to be monophyletic based on the following exclusive synapomorphies: An external row of enlarged tubercles inserted among small ones on lateral margin of the dorsal scutum (innapplicable in N. bosqenublado); the ventro-basal margin of pedipalpal tibia curved 90 degrees in lateral view; and retrolateral seta of the pedipalpal tibia with a socket apically bifid (socket and seta longer than pedipalpal tibia length).

Behavioral analysis of the interaction between the spitting spider Scytodes globula (Araneae: Scytodidae) and the harvestman Discocyrtus invalidus (Opiliones: Gonyleptidae)

Spitting spiders (Scytodidae) have a distinct predatory strategy in which they eject a sticky secretion from their cheliceral fangs to immobilize prey. This behavior could potentially allow the spider not only to avoid defensive secretions but also to bite specific vulnerable spots of a potential prey such as a harvestman. We used an ethogram, a fluxogram and an experiment to analyze the interaction between the harvestman Discocyrtus invalidus Piza 1938 (Arachnida: Opiliones) and the syntopic spider Scytodes globula (Nicolet 1849) (Arachnida: Araneae). These spiders, while readily taking crickets as prey, seldom spat at and never bit the harvestmen, which apparently did not exude repugnatorial secretions. We therefore tested, by clogging the glands and using appropriate controls, whether non-visible amounts of secretions could cause the rejection, but the harvestmen were still refused. This is the first detailed and quantified description of an interaction between a spitting spider and a harvestman. The general conclusions are that S. globula avoids preying on D. invalidus, S. globula behaves differently when attacking harvestmen and crickets and the scent gland secretions of D. invalidus do not play a direct role in this predator-prey interaction.

A new genus and species of cavernicolous Pomatiopsidae (Mollusca, Caenogastropoda) in Bahia, Brazil

Spiripockia punctatais a new genus and species of Pomatiopsidae found in a cave from Serra Ramalho, SW Bahia, Brazil. The taxon is troglobiont (restricted to subterranean realm), and is characterized by the shell weakly elongated, fragile, translucent, normally sculptured by pustules with periostracum hair on tip of pustules; peristome highly expanded; umbilicus opened; radular rachidian with 6 apical and 3 pairs of lateral cusps; osphradium short, arched; gill filaments with rounded tip; prostate flattened, with vas deferens inserting subterminally; penis duct narrow and weakly sinuous; pallial oviduct simple anteriorly, possessing convoluted bypass connecting base of bulged portion of transition between visceral and pallial oviducts with base of seminal receptacle; spermathecal duct complete, originated from albumen gland. The description of this endemic species may raise protective environmental actions to that cave and to the Serra Ramalho Karst area.

A scanning electron microscopic survey of the cuticle in Cyphophthalmi (Arachnida, Opiliones) with the description of novel sensory and glandular structures

The cuticular surfaces of Cyphophthalmi (Opiliones) were studied in detail, covering a wide range of their taxonomic diversity. Previously unknown structures are described, including a sexually dimorphic row of spines and glandular openings on leg I of Fangensis cavernarum. Scanning electron micrographs of the prosomal paired hairs and the subapical process are provided for the first time. Evidence for the multi-pored nature of the shaft of solenidia as well as the hollowed nature and absence of wall pores of sensilla chaetica are also shown for the first time using scanning electron microscopy. The prosomal paired hairs may constitute a novel autapomorphy for Cyphophthalmi, as they are absent in all studied members of the other species of Opiliones. Finally, the variation in shape of some of the structures examined may be of great taxonomic value.

Conditional male dimorphism and alternative reproductive tactics in a Neotropical arachnid (Opiliones)

In arthropods, most cases of morphological dimorphism within males are the result of a conditional evolutionarily stable strategy (ESS) with status-dependent tactics. In conditionally male-dimorphic species, the status` distributions of male morphs often overlap, and the environmentally cued threshold model (ET) states that the degree of overlap depends on the genetic variation in the distribution of the switchpoints that determine which morph is expressed in each value of status. Here we describe male dimorphism and alternative mating behaviors in the harvestman Serracutisoma proximum. Majors express elongated second legs and use them in territorial fights; minors possess short second legs and do not fight, but rather sneak into majors` territories and copulate with egg-guarding females. The static allometry of second legs reveals that major phenotype expression depends on body size (status), and that the switchpoint underlying the dimorphism presents a large amount of genetic variation in the population, which probably results from weak selective pressure on this trait. With a mark-recapture study, we show that major phenotype expression does not result in survival costs, which is consistent with our hypothesis that there is weak selection on the switchpoint. Finally, we demonstrate that switchpoint is independent of status distribution. In conclusion, our data support the ET model prediction that the genetic correlation between status and switchpoint is low, allowing the status distribution to evolve or to fluctuate seasonally, without any effect on the position of the mean switchpoint.

Efficiency of uniparental male and female care against egg predators in two closely related syntopic harvestmen

Although the benefits of maternal care have been investigated in many species, the caring role of males in species with exclusive paternal care has received less attention. We experimentally quantified the protective role of paternal care in the harvestman Iporangaia pustulosa. Additionally, we compared the effectiveness of paternal care against predation in this species with a syntopic harvestman with maternal care, Acutisoma proximum. We demonstrated that nearly one-third of the unprotected Iporangaia clutches disappeared entirely in 12 days, while the other two-thirds suffered a mean reduction of 55% in egg number. Conversely, 50% of the control clutches did not suffer any reduction, and only one was entirely consumed by predators. We also demonstrated that the mucus coat that covers Iporangaia clutches has an important deterrent role against predation by conspecifics: 58.3% of the clutches without mucus were attacked and three of them were entirely consumed, whereas only three clutches with mucus were attacked, suffering a reduction of up to three eggs. Iporangaia males were as efficient as Acutisoma females in protecting eggs. However, unattended Acutisoma eggs were attacked 20% more frequently than unattended Iporangaia eggs. Unattended Iporangaia eggs are protected by a mucus coat that prevents or decreases predation rate, whereas Acutisoma eggs are more susceptible to predation, probably because they lack this mucus coat. Thus, besides the fact that Iporangaia males efficiently protect the offspring against egg predators, females also contribute to egg protection by providing a mucus coat that deters egg predators. (C) 2009 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Paternal Care Decreases Foraging Activity and Body Condition, but Does Not Impose Survival Costs to Caring Males in a Neotropical Arachnid

Exclusive paternal care is the rarest form of parental investment in nature and theory predicts that the maintenance of this behavior depends on the balance between costs and benefits to males. Our goal was to assess costs of paternal care in the harvestman Iporangaia pustulosa, for which the benefits of this behavior in terms of egg survival have already been demonstrated. We evaluated energetic costs and mortality risks associated to paternal egg-guarding in the field. We quantified foraging activity of males and estimated how their body condition is influenced by the duration of the caring period. Additionally, we conducted a one-year capture-mark-recapture study and estimated apparent survival probabilities of caring and non-caring males to assess potential survival costs of paternal care. Our results indicate that caring males forage less frequently than non-caring individuals (males and females) and that their body condition deteriorates over the course of the caring period. Thus, males willing to guard eggs may provide to females a fitness-enhancing gift of cost-free care of their offspring. Caring males, however, did not show lower survival probabilities when compared to both non-caring males and females. Reduction in mortality risks as a result of remaining stationary, combined with the benefits of improving egg survival, may have played an important and previously unsuspected role favoring the evolution of paternal care. Moreover, males exhibiting paternal care could also provide an honest signal of their quality as offspring defenders, and thus female preference for caring males could be responsible for maintaining the trait.

Male dimorphism of a neotropical arachnid: harem size, sneaker opportunities, and gonadal investment

Serracutisoma proximum is a harvestman with alternative male morphs. Large males use sexually dimorphic second legs in fights for the possession of territories on the vegetation, where females oviposit. Small males have short second legs and do not fight but rather sneak into the territories and copulate with egg-guarding females. We investigated the presence of male dimorphism across 10 populations of S. proximum, compared gonadal investment between male morphs, and assessed if the distribution of the sneakers is influenced by harem size. In all populations, there was male dimorphism, indicated by the bimodal distribution of the leg II length/body length. Gonadal investment did not differ between morphs and was not affected by male size, second leg length, and morph relative frequency in the populations. We found 361 territories, 90.0% containing 1 male, 9.7% containing 2 males (dyads), and 0.3% containing 3 males. The probability of encountering dyads increased with the number of females present in the territories. Moreover, the proportion of sneakers in territories containing dyads was higher than would be expected by chance. One possible reason for the ubiquity of alternative morphs in S. proximum could be the high mating opportunities experienced by sneakers in spatially structured populations with a resource defense polygyny system. Additionally, the high frequency of successful invasions by sneakers and hence the high sperm competition risk for both morphs may explain the similarity in gonadal investment between male morphs.

Influence of Cave Size and Presence of Bat Guano on Ant Visitation

This is the first study which evaluated the influence of cave size and presence of bat guano in ant visitation in Brazilian caves. We provide a list of the ants associated with 27 caves in northeastern Brazil, an area situated in the transition between Cerrado (Brazilian savanna) and Amazon Domain. The study was conducted between January and August 2010. We recorded 24 ant species inserted into 12 genera, 10 tribes, and six subfamilies. The size of the cave and the presence of guano did not influence the richness of ants, and most of the caves had single species. Camponotus atriceps was the species with the larger distribution, being collected in five caves. In addition, we discuss geographic distribution of records and possible ecological roles of ants in cave environments.

Descriptions of Thereza murutinga sp. nov. and Pristocnemis caipira sp. nov., and new records of Caelopyginae (Opiliones: Laniatores: Gonyleptidae)

Two new species of Caelopyginae are described: Pristocnemis caipira sp. nov. from Parque Nacional da Serra da Canastra, Minas Gerais, Brazil, and Thereza murutinga sp. nov., from Parati, Rio de Janeiro, Brazil. Pristocnemis caipira sp. nov. is diagnosed by shallow grooves on the dorsal scutum, a lower number of tarsal segments, presence of a spine on the anal operculum, large, pointed tubercles on the lateral margins of the dorsal scutum, and an absence of white patches on the dorsal scutum. Thereza murutinga sp. nov. is diagnosed by the combination of the following characters: incomplete median longitudinal groove on area III and absent on area II, prosoma much smaller than opisthosoma, and a large white patch covering the prosoma and whole areas of the opisthosomal scutum. A cladistic analysis including the two new species was performed to investigate their relationship within the subfamily. We obtained 927 trees of 185 steps (CI=0.4, RI=0.74), which corroborated the generic assignments of the new species, but infrageneric relationships remained unsolved. In addition, male genitalia of Ampheres luteus (Giltay) and genera Pristocnemis and Thereza are redescribed, new distribution records for Caelopyginae species are presented, and biogeographical implications are discussed.