Pedro Gnaspini

Reproduction and postembryonic development of Goniosoma spelaeum, a cavernicolous harvestman from southeastern Brazil (Arachnida: Opiliones: Gonyleptidae)

Summary The reproductive characteristics of trogloxenic Goniosoma spelaeum were studied directly in the field in caves of the Ribeira River Speleological Province, Sao Paulo State, south-eastern Brazil. They reproduce throughout the year, with one marked peak during the rainy season and a second minor peak in the dry season. During copulation, the male grasps the female pedipalps with his pedidalps, and the pair keep a face-to-face position. After mating, the male stays close to the female, waving his second legs over her body while she proceeds with egg-laying. Each group contains ca. 60–80 eggs of 2.1–2.3 mm diameter. Females remain over their eggs throughout embryonic development, leaving the site only after dispersion of the nymphs begins. The post-embryonic phase contains six nymphal stages, which are characterized both morphologically and morphometrically, and lasts about 1.5 years. Secondary sexual dimorphism appears during the post-embryonic development. The adult phase lasts more than 2 years, gi...

systematic revision of Goniosomatinae (Arachnida : Opiliones : Gonyleptidae), with a cladistic analysis and biogeographical notes

Goniosomatine harvestmen have strongly armed pedipalps, generally large bodies and, commonly, very long legs (sometimes more than 20 cm), and are distributed in the Brazilian Atlantic forest, from southern Bahia to Santa Catarina. Since they are conspicuous animals and individuals of some species tend to concentrate in caves (and also under rock boulders), they have been (and still are) the target of several studies, especially those focusing on reproductive and defensive behavior, population ecology, physiology, chromosomes, etc. In spite of their importance for biological studies (some species constitute important and frequently used models for these studies), the taxonomy of Goniosomatinae has faced some problems, including misidentification, a large number of undescribed species and the lack of a phylogenetic hypothesis for the relationships among its species (which would allow evolutionary studies to be made). The last taxonomic changes in the subfamily were made 60 years ago. Considering a taxonomic revision and cladistic analysis of the subfamily to be of paramount importance, the main scope of the present paper is to provide a cladistic analysis and taxonomic revision of the species of Goniosomatinae and a new arrangement of genera (and species). The main taxonomic changes are given as follows. Six genera are recognised within the subfamily: Goniosoma; the newly described genus Pyatan; the reestablished genera Serracutisoma, Heteromitobates and Mitogoniella; and Acutisoma. New generic synonyms include: Glyptogoniosoma = Goniosomella = Lyogoniosoma = Metalyogoniosoma = Xulapona = Goniosoma, Acutisomelloides = Pygosomoides = Spelaeosoma = Serracutisoma; and Acutisomella = Heteromitobates. Newly described species include: Goniosoma capixaba; G. apoain; Pyatan insperatum DaSilva, Stefanini-Jim & Gnaspini; Serracutisoma pseudovarium; S. fritzmuelleri; S. guaricana; Heteromitobates anarchus; H. harlequin; H. alienus; Mitogoniella taquara; M. unicornis; and Acutisoma coriaceum. New combinations include: Goniosoma macracanthum (Mello-Leitao, 1922); G. unicolor (Mello-Leitao, 1932); G. carum (Mello-Leitao, 1936); Serracutisoma proximum (Mello-Leitao, 1922); S. banhadoae (Soares & Soares, 1947); S. molle (Mello-Leitao, 1933); S. thalassinum (Simon, 1879); S. catarina (Machado, Pinto-da-Rocha & Ramires, 2002); S. inerme (Mello-Leitao, 1927); S. spelaeum (Mello-Leitao, 1933); Heteromitobates inscriptus (Mello-Leitao, 1922); H. albiscriptus (Mello-Leitao, 1932); Mitogoniella modesta (Perty, 1833); and M. badia (Koch, 1839). Reestablished combinations include: Mitogoniella indistincta Mello-Leitao, 1936 and Acutisoma longipes Roewer, 1913. New specific synonyms include: Acutisomella cryptoleuca = Acutisomella intermedia = Goniosoma junceum = Goniosoma patruele = Goniosoma xanthophthalmum = Metalyogoniosoma unum = Goniosoma varium, Goniosoma geniculatum = Goniosoma venustum; Goniosomella perlata = Progoniosoma minense = Goniosoma vatrax, Glyptogoniosoma perditum = Progoniosoma cruciferum = Progoniosoma tijuca = Goniosoma dentipes; Leitaoius iguapensis = Leitaoius viridifrons = Serracutisoma proximum; Acutisoma marumbicola = Acutisoma patens = Serracutisoma thalassinum; Progoniosoma tetrasetae = Serracutisoma inerme; and Acutisoma monticola = Leitaoius nitidissimus = Leitaoius xanthomus = Mitogoniella mutila = Acutisoma longipes. The following species are considered species inquirenda: Goniosoma lepidum Gervais, 1844; G. monacanthum Gervais, 1844; G. obscurum Perty, 1833; G. versicolor Perty, 1833; and Mitogoniella badia (Koch, 1839). The monotypic genus Goniosomoides Mello-Leitao, 1932 (and its species, G. viridans Mello-Leitao, 1932) is removed from Goniosomatinae and considered incertae sedis.

An ethological approach to a SEM survey on sensory structures and tegumental gland openings of two neotropical harvestmen (Arachnida, Opiliones, Gonyleptidae)

We studied the sensory structures and tegumental glands of two harvestmen species, Neosadocus sp. and Iporangaia pustulosa. We also provide field data of dietary items and data on the foraging behavior of Neosadocus sp. in captivity. Food include mostly immobile items such as dead insects, fruits and feces; the mobility of foraging animals in starvation was greater than in satiation conditions; no trichobothria was found; metatarsal paired slit sensilla and three other sensilla are described for the first time in harvestmen. We discuss the possible relationship between sensory structures, diet and foraging mobility, comparing with other groups of Arachnida. We also describe five new tegumental glands, one sexually dimorphic in the metatarsus IV of I. pustulosa males and two that are rubbed against the substrate while walking, present in both species. This is the first morphological evidence that harvestmen might leave chemical marks on the substrate.

Spatial distribution‚ mobility‚ gregariousness‚ and defensive behaviour in a Brazilian cave harvestman Goniosoma albiscriptum (Arachnida‚ Opiliones‚ Gonyleptidae)

This study provides information on population dynamics and behaviour (gregariousness and defensive tactics) of the Brazilian cave harvestman Goniosoma albiscriptum (Goniosomatinae). Through a mark-recapture study, we observed that this species regularly uses the cave during the day, leaving it to forage on the vegetation after dusk (i.e., a trogloxene species). There were nine groups within the cave, composed of females and males, the latter being the only sex that moved from one group to another (although rarely). Distinct groups used distinct openings of the cave to leave the shelter after dusk. Goniosoma albiscriptum showed a variety of mechanical defensive behaviours, and also exuded scent gland secretions. During dryer and colder months (between April and August), adult and subadult harvestmen aggregated on the cave walls. The individuals that composed the aggregations were not always the same ones. Reproductive activity (detected by the presence of egg batches) was negatively correlated with formation of aggregations. We suggest that intolerance towards conspecifics during the reproductive period may inhibit the formation of aggregations.

Comparative study of the defensive behavior and morphology of the gland opening area among harvestmen (Arachnida, Opiliones, Gonyleptidae) under a phylogenetic perspective

The arachnids of the order Opiliones (harvestmen) have a pair of scent glands opening at the sides of the body, the substances of which are used in defense. Several types of behavioral, morphological and chemical defensive mechanisms have been assigned to the order as a whole, although some of these tactics were restricted to particular groups. Only around 25 species have been studied from this perspective so far. In the present paper, we analyzed 33 species (mostly from the largest harvestmen family, the Gonyleptidae) aiming at recognizing the usefulness of the defensive characters in taxonomy and evolutionary biology. We observed the morphology of the gland opening (ozopore) area and the defensive behavior, and their relationship, and mapped these traits on an available phylogenetic hypothesis of relationship within Gonyleptidae. As outgroups, we analyzed Cosmetidae and Stygnidae. Combining the observed behavioral characters of the emission of defensive secretion (near the ozopore, with liquid displacement through an integumentary groove, or in form of a jet) with the morphological types of the gland opening (direction of the integumentary dome that surrounds the gland opening, presence of two openings and the relationship between their sizes, and presence of a V-shaped cut at the anterior opening), we recognized eight patterns. In addition, we could examine the evolution of such traits within Gonyleptidae.

Sexually Dimorphic Tegumental Gland Openings in Laniatores (Arachnida, Opiliones), With New Data on 23 Species

Sexually dimorphic glands often release sexual pheromones both in vertebrates and invertebrates. Species of Laniatores (Arachnida, Opiliones) seem to depend on chemical communication but few studies have addressed this topic. In this study, we review the literature for the Phalangida and present new data for 23 species of Laniatores. In 16 taxa, we found previously undescribed sexually dimorphic glandular openings on the femur, patella, metatarsus, and tarsus of legs I and metatarsus of legs III and IV. For the other species, we provide scanning electron micrographs of previously undescribed sexually dimorphic setae and pegs located on swollen regions of the legs. We also list additional species in which males have swollen regions on the legs, including the tibia, metatarsus, and tarsus of legs I, trochanter and tibia of legs II, femur, metatarsus, and tarsus of legs III, and metatarsus and tarsus of legs IV. The function and biological role of the secretions released by these glands are discussed. J. Morphol., 2010.

Breeding biology of the cavernicolous harvestman Goniosoma albiscriptum (Arachnida, Opiliones, Laniatores): sites of opposition, egg batches characteristics and subsocial behaviour

Summary We present field data on seasonality, mating behaviour, sites of oviposition, characteristics of egg batches, and parental care of a cavernicolous population of the Brazilian harvestman Goniosoma albiscriptum. We also tested if guarding females became more aggressive than non-guarding ones by allowing a potential predator to approach G. albiscriptum females. Field work was conducted in several visits to a cave, from September 1999 to April 2001. Reproductive activity was detected almost the whole year, with a minor peak in the spring (October-November) and a major peak in the summer (February-March). Average sex ratio throughout the year was female biased. Proportionally, guarding females were found significantly more often in exposed places than females without eggs. No significant difference was detected between the number of eggs laid in exposed and non-exposed places. The mean number of eggs per batch was 69.58±26.96, and the average minimum time of embryonic development was 33.26±9.78 days. Twenty-nine females produced two egg batches, with no significant difference between the number of eggs laid in the first and second batch. Intervals between the two ovipositions ranged from 3 to 17 months. Laboratory tests showed that conspecifics and other cave inhabitants, such as other harvestmen species and crickets, preyed on G. albiscriptum eggs. Guarding females reacted aggressively to a non-conspecific approaching harvestman. Non-guarding females never reacted aggressively. Con-specific males near females during the day attacked conspecifics males but not males of another species. Once, a male was seen standing next to eggs and immatures, possibly guarding them.

Caves as a Winter Refuge by a Neotropical Harvestman (Arachnida, Opiliones)

Organisms may respond to regular and predictable environmental changes by migrating to regions where resources are available and/or the conditions are more favorable (Dingle and Drake 2007). Although migration is usually associated with long-distance displacements, like those of some birds and butterflies, less vagile animals may also migrate through considerably shorter distances (Kraus and Morse 2005). In fact, the term migration covers a wide range of population displacements (Dingle and Drake 2007), and includes seasonal movements into shelters where the environmental conditions are expected to be less affected by the external environmental changes. Caves are a good example of seasonal shelter, generally with a permanently high humidity and stable temperature even during the winter (Culver and Pipan 2009). Several species do indeed use caves as winter refuges, including insects (e.g. Tercafs 2000), arachnids (Holmberg et al. 1984; Novak et al. 2004), and vertebrates like bats (Lewis 1995), baboons (Barrett et al. 2004), snakes (Sexton and Hunt 1980), and frogs (Resetarits 1986). We highlight, however, that all these examples are from animals living in temperate regions. As far as we know, there is so far no record of the use of caves as winter refuges by animals that are not from temperate regions. This is probably related to the less stressful climatic conditions of the cold period when compared to the harsh winter of temperate regions. J Insect Behav (2011) 24:393–398 DOI 10.1007/s10905-011-9264-x

Comparative Density of Hair Sensilla on the Legs of Cavernicolous and Epigean Harvestmen (Arachnida: Opiliones)

To allow an animal to behave appropriately, the location of sensorial structures is expected to be related to their function. As the different leg pairs of arachnids may have different functions (probing x supporting the body), one could expect them to have a different density of sensilla. Moreover, different regions of the same leg (dorsal, lateral, and ventral) would also be expected to have different densities of sensilla, according to the use of each region (e.g., the ventral part is often in contact with the substrate while the dorsal part is not). As caverni- colous animals are expected to be more sensitive than their epigean relatives, one could also expect a different density of sensilla when comparing cavernicolous and epigean animals. Using three epigean and three caverni- colous species of harvestmen (Arachnida, Opiliones), this study aimed at describing the morphology of hair sensil- la on the legs and answering three questions: (1) Are there differences in the density of hair sensilla between the dorsal, lateral and ventral regions of each leg pair of the same individual? (2) Are there differences in the density of hair sensilla between the leg pairs of the same individual? (3) Are there differences in the density of hair sensilla when comparing the leg pairs of individuals of cavernicolous and non-cavernicolous species? The tarsi and metatarsi of all right legs of the six studied species were analyzed under a scanning electron microscope. The results (P < 0.05) showed that, in general: the ventral region of the tarsus was denser in sensilla trichodea than the lateral and dorsal regions, particularly on legs I and II; the density of sensilla chaetica did not differ on legs III and IV, but was greater on the dorsal region of legs I and II; the ventral part of legs I had the higher density of sensilla trichodea of the four pairs, whereas the second pair had the lower density; Holcobunus citrinus (Eupnoi) was the species with higher density of sensilla trichodea, on all legs; the cavernicolous species had a lower density of sen- silla than the epigean species. The results are tentatively related to harvestmen behavior.

MALE EGG GUARDING BEHAVIOR IN THE NEOTROPICAL HARVESTMAN AMPHERES LEUCOPHEUS (MELLO-LEITÃO 1922) (OPILIONES, GONYLEPTIDAE)

Abstract Males of the Neotropical harvestman Ampheres leucopheus (Mello-Leitão 1922) were observed guarding egg-batches attached to the undersurface of leaves. As recorded for other paternal harvestmen, males of A. leucopheus guard egg-batches containing eggs in different developmental stages as well as newly hatched nymphs. This is the second case of paternal care recorded among gonyleptids and the fifth in the order Opiliones.