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Morphological studies of harvestmen usually investigate the structures of adults, seldom including data regarding ontogenetic differences in the microanatomy of the appendages. In gonyleptoidean harvestmen, adults have clusters of pores on the distal-most tarsomeres of legs III and IV that are known as tarsal aggregate pores (TAPs). In gonyleptid harvestmen, these pores occur on the prolateral and retrolateral surfaces as groups adjacent to the tarsal claws. In this study, we used scanning electron microscopy (SEM) to compare the microanatomy of the TAPs occurring on leg IV of adults and antepenultimate nymphs for three common species of Neotropical cosmetid harvestmen, nymphs of an additional seven cosmetid morphospecies, and adults and antepenultimate nymphs of three species of gonyleptoidean harvestmen. The distal tarsomere of leg IV of adult cosmetid harvestmen features two pairs of aggregate pores including dorsal TAPs and ventrolateral vTAPs. The TAPs of cosmetid nymphs have denticulate bor...

The legs of laniatorean harvestmen feature a considerable diversity of setae, glandular openings, sensory structures, and tubercles. In this study, we compared the morphology of cuticular structures occurring on leg IV of 12 species of cosmetid harvestmen and six species of other gonyleptoidean harvestmen representing the families Agoristenidae, Gonyleptidae (three subfamilies), and Stygnidae. Our results indicate that there is considerable interspecific variation in rough pit glands and the tarsal perforated organ among cosmetid and gonyleptoidean harvestmen. We also found interspecific variation in the relative size, number, distribution, and morphology of the tubercles on the femur, patella and tibia. We observed relatively little interspecific variation in the morphology of sensilla chaetica, trichomes, spines, single pores, tarsal aggregated pores, and slit sensilla. Additional studies of the ultrastructure of cuticular structures, especially rough pit glands, are needed to assess their functional significance. Future systematic revisions of cosmetid taxa may also benefit from the inclusion of characters based upon interspecific variation in the microanatomical structures of the legs.

Many species roost communally but the proximate causes and ultimate functions of this widespread behavior remain poorly understood. We studied the communal roosts of two undescribed species of harvestmen in the genus Prionostemma Pocock 1903 at a Caribbean rainforest site in southeastern Nicaragua. The species are quite similar in gross morphology but differ in body coloration, male genitalia, and roosting behavior. One species roosts primarily on spiny palms while the other species, which is darker in coloration, roosts inside buttress root cavities. In a mark-recapture study, the cavity-roosting species had higher levels of individual site fidelity than found previously in the spiny palm-roosting species, perhaps because suitable cavities are scarcer than spiny palms. The tree cavity aggregations were strongly male-biased, which our review of the literature suggests is unusual for harvestman roosts. The overall sex ratio of the spiny palm aggregations was 1∶1, but some roost sites were strongly...

Most species descriptions of harvestmen from Central America that belong to the suborder Eupnoi are based on characters such as total body length, relative size of leg segments, coloration of the body and legs, and armature of the eye mound and dorsal scutum. Characters based on reproductive morphology and microanatomical structures are generally absent from most taxonomic works. Not surprisingly, the taxonomy of these harvestmen from this region requires extensive revision. In an effort to identify novel characters, we used scanning electron microscopy to compare the morphology of somatic and reproductive structures of Prionostemma vittatum (Roewer, 1910), Metopilio niger (Goodnight and Goodnight, 1942), and Metopilio ornatipes (Banks, 1909). Specifically, we investigated the morphology of the ocularium, ozopore, dorsal scutum, genital plate, pedipalp, spiracular opening on tibia II, ovipositor, and penis. We compared the morphology of these Neotropical taxa with that of a temperate sclerosomatid species, Leiobunum formosum (Wood, 1870). In general, we observed interspecific variation in the surface texture of the cuticle and the distribution of setae on the body and appendages. Potentially informative characters include cuticular structures associated with the ocularium, anterior propeltidium, meso- and metapeltidium, dorsal scutum, genital plate, pedipalp, and penis. We also observed intersexual variation with respect to morphology of Spicer's tarsal organ and the claw of the pedipalp.

Relatively little is known about factors that contribute to microhabitat selection among Central American harvestmen. In this study, we compared walking and climbing speeds for five common species from Costa Rica representing the families Cosmetidae (3 species), Gonyleptidae (1 species) and Sclerosomatidae (1 species). Our sample included two arboreal species, two species that infrequently occupy perches in the vegetation, and one species that rarely climbs. Our analyses revealed no significant interspecific differences in climbing speed, although species with relatively long legs walked significantly faster than species with shorter legs. An arboreal habit did not correlate with increased climbing speed, and all species walked significantly faster than they climbed.

In tropical rain forests, harvestmen assemblages are extremely diverse, with richness often exceeding 25 species. In the neotropics, there are published accounts of harvestmen faunas in South America rainforests (especially Amazonia), but relatively little is known about the community ecology of harvestmen in tropical forests of Central America. In this paper, we provide the first insights into the diverse assemblage of harvestmen inhabiting a wet forest at La Selva Biological Station, Costa Rica. Over five field seasons, we recorded 38 species. During our 2009 field season, we examined variation in species abundance, richness, and composition between adjacent successional forests (young secondary, mature secondary, and primary forests) as well as between distinct habitats (ground/litter layer and shrub/tree layer). Based on night samples (but not day), our results indicate that there are only minor differences in species composition and relative abundance between the forest ages, but no differences in richness. The ground/litter layer and shrub/tree layer habitats differed markedly in species composition, species richness, and relative abundance of several species. Our analysis of covariance supports the hypothesis that leg length is related to climbing behavior for several species belonging to Eupnoi and Laniatores.

In encounters with predators, sclerosomatid harvestmen may employ a variety of defensive tactics including the voluntary detachment of legs (autotomy). The long-term costs of this evasive defense are not fully understood, but prior studies have documented negative consequences for terrestrial locomotion and foraging. In this study, we investigated the impact of leg loss upon locomotion in adult harvestmen (Leiobunum spp.). In southeastern Virginia, these harvestmen regularly climb vegetation and occupy perches on tree trunks, branches, and leaves that are often 1–2 m or more above the ground. In our study, we measured walking and climbing speeds for individuals with 5, 6, 7, and 8 legs. The results of our field surveys conducted over three seasons revealed relatively high frequencies (36–63%) of leg loss. We also found that individuals with six legs occupied perches that were significantly lower in the understory than those with eight legs. In the lab, we observed significantly slower walking spe...

Natural history studies serve as important foundations for future investigations of behavioral ecology and provide biologists with critical information needed for the development of empirical research programs. Relatively little is known about the biology of most species of Neotropical harvestmen in Central America. In this field study, we investigated the activity patterns of two common species Cynorta marginalis (Cosmetidae) and Prionostemma sp. (Sclerosomatidae) in a wet tropical forest in Costa Rica. We used visual encounter surveys along randomly selected transects to compare the relative abundance of these species during morning, afternoon, evening, and late night sampling periods. To generate ethograms, we observed up to three individuals of each species for 10 min along each transect, generating 69 behavioral observations for C. marginalis and 51 for Prionostemma. Both species occupy perches on vegetation and are generally nocturnal with respect to activity. After dusk, individuals of C. marginalis actively climb, interact with conspecifics, and forage on the surfaces of small and large trees. During the day, adult Prionostemma form relatively inactive clusters of up to 40 individuals on arboreal perches and descend to the leaf litter after dusk to forage.

In Central America, the family Manaosbiidae is recorded only from Panama and Costa Rica. Four species occur in this region: Barrona williamsi Goodnight & Goodnight 1942, Bugabitia triacantha Roewer 1915, Poassa limbata Roewer 1943, and Zygopachylus albomarginis Chamberlin 1925. In this paper, we describe Barrona felgenhaueri new species (Cocle Province, Panama) and Bugabitia akini new species (Cocle Province, Panama) and report a new record for B. williamsi (Cocle Province, Panama). We used SEM to examine the penis morphology of Barrona Goodnight & Goodnight 1942 and the Caribbean species Cranellus montgomeryi Goodnight & Goodnight 1947 and Rhopalocranaus albilineatus Roewer 1932. We compared genital morphology of these species with published descriptions for Manaosbiidae from South America. With respect to genital morphology, we found that the most variable characters were the number and relative sizes of the setae that occur on the lateral margins of the ventral plate. Other features that exhib...

In July and August 2005, we investigated the use of two distinct microhabitats by harvestmen (Arachnida: Opiliones) in crappo-cocorite seasonal forest, lower montane rain forest, and upper montane rain forest of the Northern Range of Trinidad, West Indies. In addition to new locality records, geographic distributions, and microhabitat use, this article provides a preliminary understanding of the species diversity, compositional similarity, and relative harvestmen abundance among forest stands located within three types of rain forest of different altitudes found in Trinidad. We collected harvestmen inhabiting the space within and underneath decaying logs as well as the leaf litter associated with the logs. In upper montane rain forest, in addition to logs, we sampled the sheaths of palm (Euterpe broadwayi Becc. ex Broadway) fronds, another shelter commonly used by harvestmen that was especially abundant at the higher elevations. We collected 173 individuals representing eight families and 14 species. The number of harvestmen per shelter varied from 3.2 individuals per log in crappo-cocorite forest to 0.8 individual per log or palm frond sheath in upper montane rain forest. In the crappo-cocorite seasonal forest, cosmetids, sclerosomatids and stygnids were most abundant. In upper montane rain forest, cranaids and manaosbiids were the most abundant taxa, whereas cosmetids and sclerosomatids were relatively rare. Crappo-cocorite and lower montane forests were very similar in species composition but differed greatly from upper montane forest. The cosmetids Paecilaema ingleiGoodnight and Goodnight 1947, Cynortula granulata Roewer 1912, and the stygnid Stygnoplus clavotibialis (Goodnight and Goodnight 1947) were found to be strongly correlated with the crappo-cocorite and lower montane forests, whereas in upper montane forests Santinezia serratotibialisRoewer 1932 and Cranellus montgomeryiGoodnight and Goodnight 1947 were closely correlated.

A new species, Santinezia noctiscansor, most similar to members of the S. festae group, is described from central Panama; this species is the only member of the genus that occurs in Central America. Our examinations of adults and nymphs collected from Coclea nd Panama Provinces revealed that males are sexually mature as penultimate nymphs. The subadult strongly resembles the adult with respect to coloration, scutal outline, armature of femora III-IV, and penis morphology, but differs in having fewer tarsomeres on each leg, a smaller body size (scutal length and width), and a much smaller tubercle on the ventral surface of coxa IV. Natural history observations are provided for specimens collected from the field site in CocleP rovince.

Larval erythraeid mites are common ectoparasites of harvestmen (Opiliones). However, interactions between these mites and hosts in tropical environments have received little attention. In this study, we examined the prevalence and intensity of mite infestations for Neotropical harvestmen from the Caribbean island of Trinidad. Overall, the prevalence of infestation was 9.9%, with significant interspecific variation in the intensity of mite infestation and significant differences in parasitism of hosts between habitats. Harvestmen collected from lowland, crappo-cocorite forest exhibited the highest infestation rates. In our samples, the intensity of infestation varied from 1 to 17 mites per host. Examination by scanning electron microscopy revealed that harvestmen were infested by two taxa of mites, a species of Leptus and another unidentified erythraeid species. Our observations represent the first host records for erythraeid mites parasitizing harvestmen from the families Cranaidae and Manaosbiidae. Mites were found to attach preferentially to the tibia and femur of the leg (175 of 178 observations). In general, the harvestmen of Trinidad exhibited mite parasitism in a fashion similar to temperate species with respect to site of attachment and prevalence and intensity of mite infestation. In the field, we also collected an adult Cynortula sp. (Cosmetidae) that was transporting 30 gravid adults of an oribatid mite (Acariformes, Oribatida, Mixonomata). Cases of mite phoresy upon harvestmen are rare, with our observation representing the first report of phoresy by an oribatid mite upon a harvestman and the first documentation of mite phoresy upon harvestmen in the Caribbean.

Relatively little is known about the food habits of neotropical harvestmen. We used Erginulus clavotibialis (Pickard-Cambridge 1905), a locally abundant species of cosmetid harvestman in Belize, in a food choice experiment. Individuals were presented with fresh fruit (pineapple) and live invertebrate prey (termites) in an experimental chamber. This species showed a strong preference for fruit, as 72% of individuals ate it first and 67% spent the most time in the fruit-containing portion of the experimental chamber. Five E. clavotibialis (13%) consumed termites, confirming this species' ability to capture and consume live invertebrate prey. Adult males located food more quickly than nymphs. Harvestmen feeding on fruit were also significantly more active than non-feeding individuals or those preying upon termites first. Opportunistic frugivory may be important to E. clavotibialis during times when fruit is available (e.g., wet season). We hypothesize that this species exhibits a generalist diet in ...

We describe the sequence of cranial ossification in the Tailed Frog, Ascaphus truei, and examine intraspecific variation in the timing and sequence of cranial development. Because tadpoles of A. truei lack the subarticular tubercles that normally delineate Gosner stages 39 and 40, we provide a modified Gosner staging system more appropriate for this species. Ossification sequence was highly variable among the populations and greater than that reported for other anuran species. In general, early ossification events in A. truei are similar to that reported for other anuran species. However, compared with other taxa, both onset of initial ossification events and appearance of specific elements appear relatively later in the development of Ascaphus.

Adults and larvae of the loberine erotylid beetle Loberus impressus (LeConte) were found associated with fungi growing on corolla and seed capsule tissue of the blue flag iris, Iris hexagona. We examined adult beetle specimens using light and scanning electron microscopy to determine if specialized structures (mycangia) may function in transporting fungi. Two pairs of deep pits on the ventral aspect of the gena between the eyes and the maxillae of both sexes contained fungal spores and hyphae, suggesting a possible role as mycangia in addition to their role as glandular outlets. Inoculation from the surface of cleaned beetle specimens produced colonies of Cladosporium and Fusarium. These genera are widespread, usually air-dispersed conidial fungi that sometimes are associated with insects.

We describe multiple observations of epizoic cyanobacteria occurring on external surfaces of a species of sclerosomatid harvestman (Prionostemma sp.) in Costa Rica. In the field we collected four adults (three males, one female) that had green films growing upon the dorsal surfaces of the carapace and abdominal scutum. Examination by SEM revealed dense clusters of what appeared to be small prokaryotic cells (1–5 µm in diameter) covering the external surfaces of the carapace, abdominal scutum and coxae. We extracted DNA from the films of two specimens. The DNA was used as a template to amplify the intergenic spacer region (IGS) between the beta and alpha phycocyanin subunits (a signature DNA sequence, unique to cyanobacteria) by PCR. We successfully amplified an approximately 700 base pair product using DNA extracted from the film and did not obtain any product from the harvestman lacking the film. Our observation represents the second confirmed occurrence of epizoic cyanobacteria on Neotropical h...

Although relatively rare among harvestmen in the superfamily Gonyleptoidea, paternal care has been observed in the families Manaosbiidae and Gonyleptidae, but not previously in the Cosmetidae. In this study, we describe multiple observations of egg guarding by adult males of an undescribed species of cosmetid harvestman from Volcan Cacao, Guanacaste Province, Costa Rica. Observations were made from 26–28 July 2010, during the wet season. In this species, males only guard eggs after dusk, leaving eggs unattended during the day. Based upon differences in color and size, males guarded eggs through several stages of development. When guarding, males contacted the first two pairs of legs with the eggs. Oviposition sites consisted of the undersides of leaves of small plants, with eggs closely packed together in a single layer covered by abundant, transparent mucus. The largest, darkest eggs were located near the distal tip of the leaf.

Parental care in harvestmen may take several forms including egg hiding, egg guarding, egg transport and young guarding. In most species, one adult, usually the female, performs guarding of the young. From 9 July–3 August 2005, we made observations of parental care by adults of the Neotropical cranaid harvestman Phareicranaus calcariferus (Simon 1879) in northern and central Trinidad. Nine observations involved an adult female and young while three appeared to include both an adult female and male with young. The number of young present was inversely related to the size of the young, indicating that parental care in this species may occur over an extended period of time.

We recorded the number of ectoparasitic erythraeid mite larvae (Leptus sp. Latreille 1796) that were attached to 1241 Leiobunum formosum Wood 1870 from a population in southeastern Virginia. The prevalence of infestation (percent of individuals parasitized) exhibited significant annual and seasonal variation, ranging from 0.5% to 20.3%. The mean intensity of infestation (number of mites per parasitized individual) varied from 1.0 to 1.3, with a maximum observed intensity of 3 mites/individual. This study provides the first description of annual and seasonal variation in mite infestation of harvestmen.

Ambystoma). Arch. Environ. Contam. Toxicol. 32: 383-388. LILLEY, J. H., R. B. CALLINAN, S. CHINABUT, S. KANCHANAKHAN, I. H. MACRAE, AND M. J. PHILLIPS. 1998. Epizootic Ulcerative Syndrome (EUS) Technical Handbook. The Aquatic Animal Health Research Institute. Bangkok, Thailand. LUNA, L. 1968. Manual of histological staining methods of the Armed Forces Institute of Pathology. 3rd ed. McGraw-Hill Book Company, New York. MARQUEZ, R., J. L. OLMO, AND J. BOSCH. 1995. Recurrent mass mortality of larval midwife toads Alytes obstetricans in a lake in the Pyrenean mountains. Herpetol. J. 5:287-289. NYMAN, S. 1986. Mass mortality in larval Rana sylvatica attributable to the bacterium, Aeromonas hydrophila. J. Herpetol. 20:196-201. RAPHAEL, B. L. 1993. Amphibians. Vet. Clin. North Am. Small Anim. Pract. 23:1271-1285. WILLOUGHBY, L.G. 1994. Fungi and Fish Diseases. Pisces Press, Stirling, U.K. WOLF, K., G. L. BULLOCK, C. E. DUNBAR, AND M. C. QUIMBY. 1968. Tadpole edema virus: a viscerotropic pathogen for anuran amphibians. J. Inf. Dis. 118:253-262. WONG, A., AND T. BEEBEE. 1994. Identification of a unicellular, non-pigmented alga that mediates growth inhibition in anuran tadpoles: a new species of the genus Prototheca (Chlorophyceae: Chlorococcales). Hydrobiologica. 277:85-96.

Scanning electron microscopy was used to examine the morphology of the tooth crowns, and light microscopy was used to quantify the numbers and sizes of the teeth occurring on each of the major tooth-bearing bones of the ground skink, Scincella lateralis. In S. lateralis, monostichous, bicuspid teeth occur on the premaxilla, maxilla, and dentary but not on the pterygoid. No ontogenetic or sexual variation was observed in crown morphology. The sizes and numbers of teeth vary with respect to location, with dentary teeth much larger and more numerous than the teeth on the maxillary arcade. Body size was more frequently, positively correlated with tooth sizes and numbers than head width. In S. lateralis, a sexual dimorphism in the number of premaxillary teeth is present, and ontogenetic differences in tooth number and size also occur. This study represents the first complete description of

Although the qualitative features of the teeth of plethodontid salamanders have been described in considerable detail by several authors (Wake, 1966; Duellman and Trueb, 1986; Atwill and Trauth, 1988; and references therein), there have been relatively few studies that have examined quantitatively plethodontid salamander dentition (but see Stewart, 1958; Highton, 1962; Coss, 1974). Data on tooth size and number are available only for the two-lined salamander Eurycea bislineata (Stewart, 1958) and several species of Plethodon (Highton, 1962; Coss, 1974). The relationship between tooth number and body size has been explored only for vomerine teeth in several species of Plethodon (Highton,1962). No study has addressed the relationships between body size and the size and number of the teeth on all tooth-bearing bones for any plethodontid species. We investigated the relationships between tooth size and number and body size in Plethodon cinereus, a salamander that has been hypothesized to use its teeth in foraging (Regal, 1966; Duellman and Trueb, 1986), courtship (Arnold, 1972), and fighting (Thurow, 1976; Jaeger and Forester, 1993; Mathis et al., 1995). Thurow (1976) hypothesized that large size advantage in agonistic contests may be related directly to relative tooth size, that is, larger individuals have larger teeth. The possession of larger and more numerous teeth by larger individuals may also explain observed female preferences for males of large body size (Mathis, 1991). To control for factors such as age, sex, and population of origin, we studied only adult male P cinereus from a single population at Mountain Lake Biological Station, Virginia. The dentition of males unlike that of females varies seasonally (Stewart, 1958; Coss, 1974); therefore, we also examined the relationship between the season of collection and tooth number and qualitatively compared the shapes of the teeth of salamanders from our study with published descriptions (Moury et al., 1985, 1987). In P cinereus, teeth are replaced continously throughout life in a process termed zahnreihen (Lawson et al., 1971). At any one time during the life of the salamander, several loci may be either empty or contain teeth that are not yet fully functional. In our analysis, we counted and measured only teeth that were fully functional (the crown fully exposed above the oral mucosa).

We examined the effects of the physical environment on the outcome of predatory encounters between tadpoles of the frog Rana clamitans and the fishing spider, Dolomedes triton. These species co-occur in pond habitats that vary widely in dissolved oxygen and temperature. Water temperature and oxygen levels have complex effects on the behavior of anuran larvae. Behavioral responses induced by shifting physiological requirements can increase the risk of predation on tadpoles. We experimentally manipulated treatment levels of both dissolved oxygen and temperature in trials conducted between individual predators (Dolomedes) and single prey (Rana). Environmental conditions had significant effects on the behavior of tadpoles that increased the risk of attack by Dolomedes. Under the low oxygen condition, more tadpoles were eaten, and the total amount of time spent at the surface and the number of times surfaced per minute were significantly greater. For Dolomedes, increased tadpole activity resulted in the increased expression of several predatory behaviors. We found significant treatment and interaction effects on the expression of both resting and ambush postures. In addition, survival analyses showed a significantly earlier expression of predatory behaviors in decreased oxygen level treatments.

Because the morphology of the cuticular scales of spiders is extremely variable both within and between families,anny study attempting to use cuticular scales as a systematic character must first have a formal definition that differentiates scales from other types of setae. The purpose of our study was to evaluate the characters used previously in the literature to distinguish cuticular scales from other types of setae and, if necessary, to provide a new, comprehensive definition for this setal type in spiders. The results of our SEM survey of the surface morphology of the scales of 23 species of spiders representing 10 families do not support the morphology of the socket as a reliable character for distinguishing scales from other types of setae. Our results indicate that cuticular scales should be defined as flattened setae that have a pedicel bent so that the scale overlays the surface of the cuticle. Our results also suggest that the urticating hairs of theraphosid spiders should not be considered to be a type of cuticular scale. Instead, we propose the recognition of three main types of scales: lanceolate, spatulate, and plumose. In addition to qualitative comparisons, we measured and compared the cuticular scales for several species and found that differences in scale width were directly related to the morphotype of the scales being examined. Additional key words: Araneae, morphology, SEM, macrosetae, urticating hairs Of the 105 currently recognized families of spiders (Coddington & Levi 1991), 13 families have at least one species that possesses cuticular scales (Kaston 1978; Roth 1993; Townsend, unpubl. data). These families are the Anyphaenidae, Araneidae, Corinnidae, Gnaphosidae, Heteropodidae, Liocranidae, Lycosidae, Oxyopidae, Philodromidae, Pisauridae, Salticidae, Thomisidae, and Uloboridae. Thus far, the microanatomy of the cuticular scales of spiders has been described adequately only for the Salticidae (Galiano 1975; Wanless 1978a, b; Hill 1979; Cutler 1981, 1987; Cutler & Jennings 1985; Felgenhauer 1998) and the Oxyopidae (Lehtinen 1975; Townsend & Felgenhauer 1998a). In these spiders, cuticular scales exhibit a tremendous diversity of colors, distributional patterns, and morphology. In certain species, scale morphology, distributions, and colors have even been observed to vary ontogenetically (Crane 1948; Townsend & Felgenhauer 1998a, b) and sexually (Kaston 1978; Hill 1979; Townsend & Felgenhauer 1998a). At least two definitions for the cuticular scales of spiders exist in the published literature (Hill 1979; Roth 1993). According to Roth (1993), cuticular scales a Author for correspondence. E-mail: vrt5719@usl.edu are flattened setae that lack innervation and have a highly reduced socket morphology; Roth (1993) also recognized the three major morphotypes of the scales of spiders as being lanceolate, spatulate, and lamelliform. In his definition, Roth (1993) considered the urticating hairs of theraphosid spiders (i.e., tarantulas) to be a type of cuticular scale. Urticating hairs are setae that lack innervation, occur in four distinct morphotypes (Types I-IV), and typically exhibit a localized distribution, i.e., a single dense patch of hairs on the dorsal surface of the opisthosoma (Cooke et al. 1972). In contrast to Roth's definition, Hill (1979) defined a cuticular scale as being a modified, flattened seta composed of fused cuticular elements that has a pedicel bent at an obtuse angle so that the scale overlays the surface of the cuticle. In his discussion of cuticular scales in spiders, Hill (1979) made no reference to socket morphology, innervation, or homologies with the urticating hairs of tarantulas. Terminology used to describe the specific features of the surface morphology of cuticular scales of spiders was adopted by Hill (1979) from the terminology used to describe the surface features of the cuticular scales of lepidopteran insects (Downey & Allyn 1975). For instance, the proximal tip of the scale that inserts into the socket is known as the pedicel (Fig. 1). In This content downloaded from 157.55.39.163 on Wed, 21 Sep 2016 05:58:03 UTC All use subject to http://about.jstor.org/terms Cuticular scales of spiders ~~~~~~oMPw11wb-;O"a _16 *--# Figs. 1-4. SEM micrographs of the major surface features of the cuticular scales of spiders. Fig. 1. The dorsal surface of the opisthosoma of the salticid spider, Phidippus audax. Note the bent pedicel (p) of a scale. Scale bar, 30 pm. Fig. 2. Inferior surface of the cuticular scales from the prosoma of the salticid spider, Hentzia mitrata. Inferior spine (is). Scale bar, 10 pm. Fig. 3. The dorsal surface of the prosoma of the oxyopid spider, Oxyopes salticus. Note plicae (pl) occurring on the superior surface of a scale. Scale bar, 15 wLm. Fig. 4. The prosoma of the anyphaenid spider, Aysha velox. Note setule (sl) originating from the lateral surface of a scale. Scale bar, 20 lim. jumping spiders, the pedicel is bent so that an -135? angle is formed between the pedicel and the blade of the scale (Hill 1979). Small projections occurring on the lateral, inferior, and superior surfaces, as well as at or near the tip, are termed spines and are named on the basis of their location. For example, projections occurring near the tip are known as apical spines, whereas those occurring on the inferior surface are known as inferior spines (Fig. 2). Ridges, in turn, that are arranged in a longitudinal orientation along the long axis of the scale are called shafts, whereas smaller, lateral ridges are termed plicae (Fig. 3). Small lines or depressions on the superior or inferior surfaces are known as striae, while long, relatively thin processes that arise from the lateral surfaces are called setules (Fig. 4). In contrast to the paucity of research devoted to the cuticular scales of spiders, the morphology and ultrastructure of the scales of lepidopteran insects have been examined in many studies (Snodgrass 1935; Overton 1966; Chapman 1969; Greenstein 1972; Ghiradella 1974, 1984, 1985, 1989, 1994; Nijhout 1980). In these insects, cuticular scales have been observed to serve multiple functions (Scoble 1995) including defense (Robinson et al. 1969), thermoregulation (Chapman 1969), and communication (Birch et al. 1990). In spiders, scales have been hypothesized to function in similar capacities (Simon 1901-1903; Hill 1979; Cutler 1987), but no empirical research has been published that has experimentally tested any of these proposed functions. The general purpose of our study was to examine and evaluate the morphological characteristics of cuticular scales that were proposed originally by Hill (1979) and Roth (1993) and, by doing so, provide a comprehensive definition for cuticular scales in spiders. In addition, through a comparison of the surface morphology of cuticular scales and urticating hairs, we sought to clarify the relationship between these two distinct types of setae. To accomplish these tasks, a 319