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Abstract

Because the morphology of the cuticular scales of spiders is extremely variable both within and between families, any 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.

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... Setae in spiders have different morphologies and diverse functions depending on their location on the body (Ovtsharenko 1985;1989). Only 13 of the 134 known spider families have been studied on setae morphology (Townsend & Felgenhauer, 1998). Although the studies have mostly focused on ground spiders (Gnaphosidae), lynx spiders (Oxyopidae), and jumping spiders (Salticidae), there have been little or no studies on other families. ...
... They are located mostly on the abdomen and may also cover the cephalothorax, legs, pedipalps, and spinnerets. They have no connection with sensory receptor cells (Townsend & Felgenhauer, 1998). It has been recognized that there are 10 different types of setae on the cuticle of all spiders. ...
... Considering the spider families examined, lanceolate, spatulate, and plumose setae are commonly observed in spiders. There are almost no studies covering setae morphology in members of the family Thomisidae (Townsend & Felgenhauer, 1998;Gawryszewski, 2014;Baltayeva et al., 2024). According to these studies, Baltayeva reported that there are no cover setae in species Synema plorator (O. ...
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The present study aims to determine the covering setae in the two crab spiders using scanning electron microscopy (SEM). The setae on the prosoma of Runcinia grammica (C. L. Koch, 1837) and Thomisus onustus Walckenaer, 1805 were examined. This study reveals the existence of a new type of covering setae in Thomisidae group.
... In terrestrial arthropods such as spiders and lepidopteran insects, cuticular scales are flattened, typically hollow setae that are composed of two distinct asymmetrical layers, the upper and lower laminae (Ghiradella 1998;Townsend and Felgenhauer 1998a, 1998b, 1999. In both spiders and insects, the proximal tip of a cuticular scale is referred to as the pedicel (Hill 1979). ...
... In both spiders and insects, the proximal tip of a cuticular scale is referred to as the pedicel (Hill 1979). In spiders, each pedicel is bent and inserts into a socket that exhibits a reduced morphology (Townsend and Felgenhauer 1998b). Thus far, only the scales of jumping spiders (Salticidae) and lynx spiders (Oxyopidae) have been examined and described, usually with the aid of scanning electron microscopy (Hill 1979;Townsend and Felgenhauer 1998a, 1998b, 1998c, 1999. ...
... In spiders, each pedicel is bent and inserts into a socket that exhibits a reduced morphology (Townsend and Felgenhauer 1998b). Thus far, only the scales of jumping spiders (Salticidae) and lynx spiders (Oxyopidae) have been examined and described, usually with the aid of scanning electron microscopy (Hill 1979;Townsend and Felgenhauer 1998a, 1998b, 1998c, 1999. In these spiders, the morphology and color of the scales may vary with ontogeny, sex, and region of the body (Crane 1948;Hill 1979;Townsend and Felgenhauer 1998a, 1998b, 1998c, 1999. ...
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This study presents the first complete description of the external and internal morphology of cuticular scales of spiders of the genus Hamataliwa and is also the first examination of intrageneric variation in the morphology of the scales of the lynx spiders (Oxyopidae). The cuticular scales of nine species, including taxa from Australia and Central and North America, were examined using scanning electron microscopy, paraffin carving, and transmission electron microscopy (whole mounts only). The surface morphology and internal anatomy of the scales exhibit considerable intra- and inter-specific variation. The structures that exhibit the most variation are (i) the plicae, small lateral ridges on the dorsal surface, which show variation in both morphology and pattern, and (ii) the rod-shaped, branched cuticular elements that occur within the lumina, which vary most dramatically in pattern. Scale morphology also varies regionally (i.e., with respect to location on the body) in most species. A comparison of the morphology of scales of Hamataliwa spp. with those of the striped lynx spider, Oxyopes salticus, and the green lynx spider, Peucetia viridans, suggests that scales may represent a useful phylogenetic character for understanding relationships both within and between genera in the Oxyopidae.
... Despite considerable diversity in scale microanatomy and the widespread occurrence of these setae in spiders (i.e. scales are known to occur in at least 16 families: Townsend & Felgenhauer, 1998b), cuticular scales are rarely employed as taxonomic or phylogenetic characters. Most systematic studies of spiders only provide general descriptions of scale shape, colour and distribution (Brady, 1964(Brady, , 1970(Brady, , 1975Wanless, 1978a,b;Platnick & Shadab, 1980;Cutler, 1981Cutler, , 1987Cutler & Jennings, 1985). ...
... Lanceolate and spatulate scales differ from each other in their relative dimensions. In general, lanceolate scales are more elongate but not as wide as spatulate scales (for a morphometric comparison of these scale types, see Townsend & Felgenhauer, 1998b). ...
... With respect to external morphology, cuticular scales of lynx spiders all possess distinct, asymmetrical superior (upper lamina) and inferior surfaces (lower lamina). This same morphological feature is exhibited by the scales of jumping spiders (Hill, 1979;Townsend & Felgenhauer, 1998b). Interspeci®c variation in scale microanatomy occurs for various features including the general shape of the apex and number of apical spines (Fig. 2a±d), the morphology and occurrence of spines on the lower lamina (Fig. 2e, f ), upper lamina ( Fig. 3a±c), and lateral surfaces (Fig. 3d±f ), the number of shafts (Fig. 1), and the occurrence, shape and pattern of plicae (Figs 4 & 5) that may or may not interconnect to form windows (small, regularly spaced structures: Downey & Allyn, 1975;Ghiradella, 1998;Townsend & Felgenhauer, 1999a) on the upper lamina (Appendices 1 & 2). ...
Article
In spiders, cuticular scales are flattened, hollow setae that occur in a variety of shapes and colours. Using transmission electron microscopy and scanning electron microscopy, we examine and provide descriptions of the external and internal anatomy of prosomal and opisthosomal scales of 70 species of lynx spiders (Araneae, Oxyopidae), representing the genera Hamataliwa, Hostus, Oxyopes, Peucetia, Schaenicoscelis, Tapinillus, and Tapponia. The cuticular scales of these taxa exhibit regional (with respect to location on the body), sexual, inter- and intrageneric variation in external and internal morphology. In the genera, Peucetia, Schaenicoscelis, and Tapinillus, cuticular scales are plumose and only occur on the prosoma. Species of the genera Hamataliwa and Tapponia, have lanceolate scales that occur on the prosoma, legs, and opisthosoma. Hostus has spatulate scales in these areas. In the genus Oxyopes, most species have lanceolate scales on the prosoma and spatulate scales on the legs and opisthosoma. Examinations of the genitalia of 82 species of lynx spiders, revealed a strong correlation between genitalic morphology and scale shape and distribution.
... In the aviculariines, as well as in other subfamilies (e.g., Selenocosmiinae, Ornithoctoninae), the epitrichobothrial setae form a dense patch intermixed with the filiform and clavate trichobothria (Guadanucci 2012). (Fig. 11.6c, g- Townsend and Felgenhauer (1998) and defined scales as setae inserted in small sockets and bent immediately after its insertion, so that the setae overlay close to the surface of the cuticle. According to Townsend and Felgenhauer (1999), scales comprise a specific type of setae because they lack innervation. ...
... According to Townsend and Felgenhauer (1999), scales comprise a specific type of setae because they lack innervation. There has been a great diversity of spider cuticular scales described in araneomorphs (Hill 1979;Townsend and Felgenhauer 1998, but just few Theraphosidae taxa were included in these studies. In the case of tarantulas, these setae can be seen, under the microscope, as a whitish sub-layer below the numerous tactile setae. ...
Chapter
The Aviculariinae spiders sensu lato are known as the American arboreal tarantulas. They are characterized mainly by having legs with few or no spines, laterally extended tarsal and metatarsal scopulae, resulting in a spatulate appearance of the appendices, absence of spiniform setae on the prolateral maxillae, females with completely separated spermathecae, males with palpal bulb with subtegulum not extended, and long and thin embolus without keels (except Antillena). Some Aviculariinae, together with all Theraphosinae, are the only spiders that evolutionarily acquired urticating setae as a defense mechanism. The primary mechanism for releasing the urticating setae in Theraphosinae is by the friction of the legs with the abdomen, which throws the urticating setae into the air, in contrast, in most Aviculariinae the releasing mechanism occurs by direct contact. The Aviculariinae tarantulas have received considerable taxonomic and biological attention and the validity as a monophyletic group has been discussed extensively. Some phylogenetic studies suggest at least two subfamilies for the American arboreal tarantulas and their kin: Aviculariinae and Psalmopoeinae. Likewise, the phylogenetic relationships of these groups have been questioned, linking these tarantulas more closely with African or American taxa. Taxonomy, systematics and some aspects of its natural history, behavioral and distribution are addressed in this chapter.
... In the aviculariines, as well as in other subfamilies (e.g., Selenocosmiinae, Ornithoctoninae), the epitrichobothrial setae form a dense patch intermixed with the filiform and clavate trichobothria (Guadanucci 2012). (Fig. 11.6c, g- Townsend and Felgenhauer (1998) and defined scales as setae inserted in small sockets and bent immediately after its insertion, so that the setae overlay close to the surface of the cuticle. According to Townsend and Felgenhauer (1999), scales comprise a specific type of setae because they lack innervation. ...
... According to Townsend and Felgenhauer (1999), scales comprise a specific type of setae because they lack innervation. There has been a great diversity of spider cuticular scales described in araneomorphs (Hill 1979;Townsend and Felgenhauer 1998, but just few Theraphosidae taxa were included in these studies. In the case of tarantulas, these setae can be seen, under the microscope, as a whitish sub-layer below the numerous tactile setae. ...
Chapter
Studying morphology of Theraphosidae spiders can be very challenging, especially if the main objective is assembling characters for systematics. Such spiders present a homogeneous morphology, which, according to some specialists, has driven the attention of systematists to other groups of Araneae. Nevertheless, a great diversity of cuticular structures has been overlooked until the widespread use of scanning electron microscopy (SEM) in the last years for theraphosids. Among all mygalomorphs, Theraphosidae spiders possess the greatest variety of cuticular features. Data regarding cuticular features are still incipient, but we have been gathering massive quantity of SEM images of all parts of the spider body, revealing interesting structures to be used in systematics and investigated for functional morphology. In addition to the well-known tarsal adhesive setae of theraphosids and the urticating setae of Theraphosinae, we found putative chemosensitive setae, a great variety of stridulating setae, distinct morphologies of leg and palpal structures, including cuticular projections, labial and maxillary cuspules, trichobothria, as well as other enigmatic features. In this chapter, we aim to present a comprehensive revision of cuticular features of New World Theraphosidae spiders, with descriptions and micrographs.
... Other cuticular structures that have been found in mygalomorph spiders are trichobothria (Guadanucci, 2012), adhesive tarsal setae , labial and maxillary cuspules (Pérez-Miles & Montes de Oca, 2005), epiandrous glands (Ferretti et al., 2017) and chemosensory setae . Scales in spiders comprise a specific type of setae because they lack innervation (Townsend & Felgenhauer, 1999) and are defined as setae inserted in small sockets and bent immediately after their insertion (Townsend & Felgenhauer, 1998;Ramírez, 2014). The presence of scales is more common in araneomorphs than mygalomorphs and is responsible, in many cases, for the characteristic colour of Journal of Insect Biodiversity and Systematics 2024  10 (2) many spiders (Foelix et al., 2013;Guadanucci et al., 2020). ...
Article
The spiders of the genus Trichopelma Simon, 1888 present in Cuba, are revised. Currently, the genus Trichopelma comprises 22 known species distributed in the Caribbean, and Central and the upper region of South America. Cuba currently hosts five valid species and, in this study, the descriptions of seven new species distributed throughout the island are presented: T. baracoense sp. nov. (♂♀, Guantanamo prov.), T. cheguevarai sp. nov. (♂, Ciego de Ávila prov.), T. citma sp. nov. (♀, Granma prov.), T. fidelcastroi sp. nov. (♂♀, Holguín prov.), T. granmense sp. nov. (♂♀, Granma prov.), T. rudloffi sp. nov. (♂♀, Holguín prov.) and T. soroense sp. nov. (♂♀, Artemisa prov.). Based on morphological characters, a cladistic analysis was performed, revealing the phylogenetic position of the new species compared to the species previously described. Based on this phylogeny, morphological characters and close proximity in distribution, T. banksia Özdikmen & Demir, 2012 syn. n., is proposed as a junior synonym of T. cubanum (Simon, 1903). The genus Thalerommata Ausserer, 1871 is reported from Cuba for the first time, with the description of T. anae sp. nov. (♂, Sancti Spíritus prov.).
... Spider visual ornaments are composed of scales, flattened setae overlying the surface of the cuticle (Townsend and Felgenhauer, 1999). There are three different acknowledged scale types, lanceolate, spatulate, and plumose scales, each with divergent shape and structure (Townsend and Felgenhauer, 1998). Spider scales sometimes have embedded pigment, structural or florescent coloration (Andrews et al., 2007, Oxford and Gillespie, 1998, Taylor and McGraw, 2007. ...
Chapter
A spider's life is guided by sensory information completely alien to human observers unless specialised equipment is applied. Even in the case of spiders guided by vision, a sensory mode that humans can boast great acuity in, a large body of evidence suggests that spiders are most sensitive to ultraviolet light, light completely imperceptible to humans. The spider's world is thus unknown and only in the last two decades have researchers begun to make strides into understanding these fascinating creatures. Communication research has been a critical piece of the puzzle in our embryonic understanding of spiders. Although spiders generally live a solitary life, it has long been accepted that communication plays an important role throughout their lifetime. Spiders are now the subjects of intensive scientific research as it becomes more and more obvious that their communication systems are unique, highly complex, plastic and versatile. Introduction. Generally, communication takes place when a signal is sent from one individual to another that alters the pattern of behaviour or the physiology in another organism (Wilson, 1975). Three processes are required for communication: the production of a signal or cue by a sender, its propagation through the environment via a transmission channel, and appropriate receptor sites to detect the signal by the receiver. The transmission channels used by spiders are chemical, tactile, acoustic and visual channels (Weygoldt, 1977, Witt and Rovner, 1982).
... Their structural colors arise mostly from modified hairs (scales) but also from solid cuticle (see Sect. 23.4). Scales are defined as flattened hairs (setae) that have a pedicel bent near the socket, so that the scale lies close and parallel to the surface cuticle (Hill 1979;Townsend and Felgenhauer 1998). Although the size and shape of scales vary a great deal among the 5,000 species of salticids, they may be roughly grouped into three types: lanceolate, spatulate, and lamelliform (Roth 1993). ...
Chapter
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Structural colors are described and analyzed in theraphosid and salticid spiders. Some theraphosids are brightly blue: this is caused by special hairs with a lamellated wall that causes an interference of the incoming light. The incident white light is then reflected as a deep blue. In some cases, the hairs are bright yellow: there the hair wall exhibits a fine cuticular meshwork of slightly different dimensions than in the blue hairs but also results in interference, and the reflected light appears yellow. In salticids, iridescent colors are produced by flattened hairs (scales). Golden scales have a rather simple structure of two thin cuticular layers on the outside and a narrow air space in between. Blue iridescent scales are more complex, with multilayered scale walls and fine ridges on the surface that act as a diffraction grating. The body cuticle (e.g., chelicerae and eye lenses) may also be brightly colored due to light interference on many thin cuticular layers. The biological significance of structural colors in spiders is well understood in the diurnal salticids where optical signals are exchanged in courtship, usually in bright daylight. In contrast, theraphosids are mostly active at night and visual communication hardly plays any role. Their coloration may be of advantage at dawn during their defensive behavior, when the brightly colored blue and yellow legs are raised toward an aggressor.
... To gain insight into the phylogenetic relationships of the Australian lynx spiders and to provide more information concerning the basic biology and morphology of these spiders, we examined and compared the genitalic morphology (male and female) and the cuticular scales of eight species of Australian lynx spiders that are presently placed in the genus Oxyopes. Interspecific variation in the morphology of the cuticular scales was investigated and surveyed because these setae have recently been identified as sources for potentially useful taxonomic and phylogenetic characters (Townsend and Felgenhauer 1998a, 1998b, 1999a, 1999b, 2001. In addition, we sought to provide further illumination regarding the evolutionary origins of these spiders by comparing their morphology with that of representative species of the genus from Africa, Asia, and North America. ...
Article
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We examined the morphology of the genitalia and cuticular scales of eight species of Australian lynx spiders of the genus Oxyopes and compared them with those of representative species from Africa, Asia and North America. Our results indicate that the eight species examined are representative of two distinct species groups of Oxyopes in Australia. The first group consists ofO. amoenus, O. dingo, O. gracilipes, O. molarius, O. rubicundus, and O. variabilis. The evolutionary origin of these spiders is difficult to discern as they share multiple genitalic characters with African and Asian taxa. However, these six species display two characters, leg scales and internal cuticular elements in the opisthosomal scales, that are exhibited by African, but not Asian, taxa. The second group consists of Oxyopes macilentus and O. papuanis. These taxa exhibit many of the same morphological features, exhibited by Asian, but not African, species.
Chapter
Spiders are often underestimated as suitable behavioural models because of the general belief that due to their small brains their behaviour is innate and mostly invariable. Challenging this assumption, this fascinating book shows that rather than having a limited behavioural repertoire, spiders show surprising cognitive abilities, changing their behaviour to suit their situational needs. The team of authors unravels the considerable intra-specific as well as intra-individual variability and plasticity in different behaviours ranging from foraging and web building to communication and courtship. An introductory chapter on spider biology, systematics and evolution provides the reader with the necessary background information to understand the discussed behaviours and helps to place them into an evolutionary context. Highlighting an under-explored area of behaviour, this book will provide new ideas for behavioural researchers and students unfamiliar with spiders as well as a valuable resource for those already working in this intriguing field.
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Hortipes Bosselaers and Ledoux (type species Hortipes luytenae Bosselaers and Ledoux from South Africa) is a genus of small (1.5-4 mm), pale, mainly soil-dwelling spiders from sub-Saharan Africa. The genus, which is tentatively placed in the Liocranidae, is characterized by the presence of a peculiar ellipsoidal array of setae on the dorsal side of metatarsi I and II and by the large anterior median eyes with a dark retina restricted to the median portion. Ledoux and Emerit (1998) described five more species from Ivory Coast and Gabon. Sixty-three additional Hortipes species are described here as new: H. platnicki (♀), H. castor (♂ ♀), H. pollux (♂ ♀), H. fastigiensis (♂ ♀), H. ostiovolutus (♂ ♀), H. salticola (♂ ♀), H. exoptans (♂ ♀), H. scharffi (♂ ♀), H. cucurbita (♂ ♀), H. hesperoecius (♀), H. klumpkeae (♀), H. aurora (♂ ♀), H. echo (♀), H. stoltzei (♂), H. creber (♂ ♀), H. orchatocnemis (♂ ♀), H. contubernalis (♂ ♀)', H. mesembrinus (♀), H. coccinatus (♂ ♀), H. wimmertensi (♂ ♀), H. irimus (♀), H. licnophorus (♀), H. schoemanae (♂ ♀), H. aelurisiepae (♀), H. hyakutake (♂), H. rothorum (♂) H. griswoldi (♂), H. oronesiotes (♂ ♀), H. penthesileia (♀), H. zombaensis (♂ ♀), H. atalante (♀), H. merwei (♂ ♀), H. leno (♂ ♀), H. mulciber (♀), H. libidinosus (♂ ♀), H. delphinus (♂ ♀), H. bjorni (♂), H. amphibolus (♀), H. hastatus (♂ ♀), H. horta (♀), H. angariopsis (♀), H. falcatus (♂ ♀), H. lejeunei (♂ ♀), H. narcissus (♂ ♀), H. auriga (♂), H. puylaerti (♀), H. chrysothemis (♀), H. machaeropolion (♂ ♀), H. centralis (♀), H. tarachodes (♂ ♀), H. terminator (♂), H. baerti (♂), H. robertus (♂ ♀), H. abucoletus ♀, H. alderweireldti (♂), H. architelones (♂ ♀), H. calliblepharus (♂), H. fortipes (♂), H. bosmansi (♂ ♀), H. sceptrum (♂ ♀), H. anansiodatus ♀, H. hormigricola (♂ ♀), and H. depravator (♂). The genus has a vast Afrotropical distribution, occurring from as far south as East London in South Africa to Sierra Leone in western Africa. So far, no specimens are available from northeastern tropical Africa. Apart from H. merwei, which seems to prefer grassland, all species are found in leaf litter or the canopy of different kinds of forests and dense thickets. In captivity, H. contubernalis readily fed on Collembola. Specimens raised from cocoons obtained in the laboratory reached adulthood after three molts. A cladistic analysis of the 34 species for which both sexes are known, largely based on secondary genitalic characters, is proposed.
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The study pursues the description of covering setae across the whole family Gnaphosidae with using SEM. A detailed morphology of the setae of ground spiders (Araneae, Gnaphosidae) is presented. The six major types of covering setae recognized among gnaphosid spiders: squamose, plumose, lanceolate, pinnate, arborate, and sicate setae. Squamose setae are characteristic to Micaria lenzi and Nauhea tapa species. Plumose setae are more common in ground spiders and occur in genera Drassodes, Haplodrassus, Anagraphis, Nodocion, Zelotes, and species Berlandina caspica, Nomisia aussereri, Minosiella intermedia, Sosticus loricatus, Leptodrassus memorialis, Intruda signata, Parasyrisca caucasica, Scopoides catharius, Echemoides tofo, Zimiromus medius, Encoptarthria echemophthalma, Apodrassodes trancas, Apopyllus silvestri, Hemicloea sundevalli, Zelanda erebus, Orodrassus assimilis, Callilepis nocturna, and Synaphosus turanicus. Species Matua valida, Anzacia gemmea, Hypodrassodes maoricus, Homoeothele micans, and Scotophaeus blackwalli have lanceolate setae. Spiders of genus Gnaphosa have pinnate setae. Fedotovia uzbekistanica has arborate setae. Species Cesonia bilineata, Herpyllus propinquus, Litopyllus temporarius, Aphantaulax seminigra, and Kishidaia conspicua have sicate setae. Some genera, such as Drassodes and Synaphosus have a combination of different types of setae on their opistosoma, whereas others, like Eilica sp., Laronius erawan, Urozelotes rusticus, have no covering setae on their opistosoma at all. The study reveals the existence of different types of covering setae and provides a set of characteristics important for classification and phylogenetic analysis of the spider family Gnaphosidae.
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A phylogenetic analysis of the two-clawed spiders grouped in Dionycha is presented, with 166 representative species of 49 araneomorph families, scored for 393 characters documented through standardized imaging protocols. The study includes 44 outgroup representatives of the main clades of Araneomorphae, and a revision of the main morphological character systems. Novel terminology is proposed for stereotyped structures on the chelicerae, and the main types of setae and silk spigots are reviewed, summarizing their characteristics. Clear homologs of posterior book lungs are described for early instars of Filistatidae, and a novel type of respiratory structure, the epigastric median tracheae, is described for some terminals probably related with Anyphaenidae or Eutichuridae. A new type of crypsis mechanism is described for a clade of thomisids, which in addition to retaining soil particles, grow fungi on their cuticle. Generalized patterns of cheliceral setae and macrosetae are proposed as synapomorphies of the Divided Cribellum and RTA clades. Dionycha is here proposed as a member of the Oval Calamistrum clade among the lycosoid lineages, and Liocranoides, with three claws and claw tufts, is obtained as a plausible sister group of the dionychan lineage. The morphology of the claw tuft and scopula is examined in detail and scored for 14 characters highly informative for relationships. A kind of seta intermediate between tenent and plumose setae (the pseudotenent type) is found in several spider families, more often reconstructed as a derivation from true tenent setae rather than as a phylogenetic intermediate. Corinnidae is retrieved in a restricted sense, including only the subfamilies Corinninae and Castianeirinae, while the ‘‘corinnid’’ genera retaining the median apophysis in the copulatory bulb are not clearly affiliated to any of the established families. Miturgidae is redefined, including Zoridae as a junior synonym. The Eutichuridae is raised to family status, as well as the Trachelidae and Phrurolithidae. New synapomorphies are provided for Sparassidae, Philodromidae, and Trachelidae. Philodromidae is presented as a plausible sister group of Salticidae, and these sister to Thomisidae; an alternative resolution placing thomisids in Lycosoidea is also examined. The Oblique Median Tapetum (OMT) clade is proposed for a large group of families including gnaphosoids, trachelids, liocranids, and phrurolithids, all having the posterior median eye tapeta forming a 90u angle, used for navigation by means of the polarized light in the sky as an optical compass; prodidomines seem to have further enhanced the mechanism by incorporating the posterior lateral eyes to the system. The Teutamus group is recognized for members of the OMT clade that are usually included in Liocranidae, but not closely related to Liocranum or phrurolithids. The Claw Tuft Clasper (CTC) clade is proposed for a group of families within the OMT clade, all having a peculiar mechanism grasping the folded base of the claw tuft setae with a hook on the superior claws. The CTC clade includes Trachelidae, Phrurolithidae, and several gnaphosoids such as Ammoxenidae, Cithaeronidae, Gnaphosidae, and Prodidomidae. A remarkable syndrome involving the expansion of the anterior lateral spinnerets, often sexually dimorphic, is here reported for some Miturgidae and several members of the CTC clade, in addition to the known cases in Clubionidae and ‘‘Liocranidae.’’ The following genera are transferred from Miturgidae to Eutichuridae: Calamoneta, Calamopus, Cheiracanthium, Cheiramiona, Ericaella, Eutichurus, Macerio, Radulphius, Strotarchus, Summacanthium, and Tecution; Lessertina is transferred from Corinnidae to Eutichuridae. The following genera are transferred to Miturgidae: Argoctenus, Elassoctenus, Hestimodema, Hoedillus, Israzorides, Odomasta, Simonus, Thasyraea, Tuxoctenus, Voraptus, Xenoctenus, Zora, and Zoroides, from Zoridae; Odo and Paravulsor, from Ctenidae; Pseudoceto from Corinnidae. The following genera are transferred from Corinnidae to Trachelidae: Afroceto, Cetonana, Fuchiba, Fuchibotulus, Meriola, Metatrachelas, Paccius, Paratrachelas, Patelloceto, Planochelas, Poachelas, Spinotrachelas, Thysanina, Trachelas, Trachelopachys, and Utivarachna. The following genera are transferred from Corinnidae to Phrurolithidae: Abdosetae, Drassinella, Liophrurillus, Plynnon, Orthobula, Otacilia, Phonotimpus, Phrurolinillus, Phrurolithus, Phruronellus, Phrurotimpus, Piabuna, and Scotinella. Dorymetaecus is transferred from Clubionidae to Phrurolithidae. Oedignatha and Koppe are transferred from Corinnidae to Liocranidae. Ciniflella is transferred from Amaurobiidae to Tengellidae.
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Urticating setae are exclusive to New World tarantulas and are found in approximately 90% of the New World species. Six morphological types have been proposed and, in several species, two morphological types can be found in the same individual. In the past few years, there has been growing concern to learn more about urticating setae, but many questions still remain unanswered. After studying individuals from several theraphosid species, we endeavored to find more about the segregation of the different types of setae into different abdominal regions, and the possible existence of patterns; the morphological variability of urticating setae types and their limits; whether there is variability in the length of urticating setae across the abdominal area; and whether spiders use different types of urticating setae differently. We found that the two types of urticating setae, which can be found together in most theraphosine species, are segregated into distinct areas on the spider's abdomen: type III occurs on the median and posterior areas with either type I or IV surrounding the patch of type III setae. Morphological intermediates between types I and III, as well as between III and IV, were found. We propose that type III urticating setae have evolved through modifications of body setae on specific areas of abdomen dorsum and subsequently gave independent origin to areas having either type I or IV. A parallel evolution seems to have occurred in some aviculariine genera in which type II setae evolved also from body setae from specific areas of abdomen dorsum. Concerning the length of the setae, we observed that towards the median and posterior areas of the abdomen the length of the urticating setae increases. These long setae are cast by the spider as part of an active defensive behavior against vertebrate predators. We propose that spiders use the various types of urticating setae differently and according to their different targets: type I setae, when incorporated either into the molting web or eggsac, is more effective against invertebrates (ants or phorid fly larvae) than type III. The latter seems to be used mainly against vertebrate predators.
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The form and location of the scales of salticid spiders, as revealed by light and scanning electron microscopy, provide useful diagnostic characters for the separation of species, the assignment of species to genera, and a further understanding of the relationships between salticid genera. Partly on the basis of distinctions provided by scale structure, the new genus Platycryptus, type-species Aranea undata De Geer, 1778, is defined. Metaphidippus vitis Cockerell, 1894, is placed in the genus Sassacus Peckham, 1895, and Paromaevia michelsoni (Barnes), 1955, is returned to the genus Maevia. The placement of Eris, Hentzia, Icius, Metaphidippus, Phidippus, and Sassacus in the subfamily Dendryphantinae is substantiated; Tutelina and Zygoballus are added to this group. On the basis of common scale structure, Evarcha, Habrocestum, Menememerus, Phlegra, Platycryptus, and Sitticus are tentatively assigned to the subfamily Habrocestinae. Scales of Anasntis, Corythalia, Cosmophasis, Hyllus, Marpissa, Metacyrba, Pellenes, Plexippus, Salticus, Sarinda, and Thiodina are also described.
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An examination of the cuticular scales of the lynx spiders Oxyopes aglossus, O. salticus, and Peucetia viridans using scanning electron microscopy revealed that scales in these spiders are morphologically distinct, yet similar to the scales of the jumping spiders Eris militaris and Hentzia mitrata. Like the cuticular scales of jumping spiders, the cuticular scales of lynx spiders exhibit morphological differentiation in regard to location of occurrence on the body, with scales near the eyes tending to have more numerous and larger spines on the superior surface than scales on other regions of the prosoma and opisthosoma. The functional significance of this differentiation in scale morphology is unknown. Sexual dimorphism and ontogenetic variation in scale morphology and color were observed in the genus Oxyopes,but not in Peucetia. In addition, the scales of P. viridans were distinguishable from the scales of Oxyopes spp. on the basis of the number of apical spines (1 in P. viridans instead of 3–7 in Oxyopesspp.) and on the presence of spines on the inferior surface (many in P. viridans and none in Oxyopesspp.). J. Morphol. 236:223-231, 1998. © 1998 Wiley-Liss, Inc.
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Light and electron microscope studies of development of the ultraviolet-reflecting scales of male Colias eurytheme butterflies show that basic developmental processes are similar to those of other scales. The ridges form between bundles of microfilaments and as they form they buckle to produce the lamellae seen in the adult scales. There is evidence that the buckling may be purely in response to mechanical stress and that some of the bundles of microfilaments may produce such stresses.
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Color patterns on lepidopteran wings are believed to be organized around a series of hypothetical foci. Foci presumably serve as sources of positional information, directing synthesis of appropriate pigments in their vicinity. Species-specific color patterns arise by variations in the number of foci on the wing and variations in the rules by which positional information is interpreted. The present paper provides experimental evidence for the existence of a focus that determines the large eyespot on the forewing of the Buckeye butterfly,Precis coenia. Cautery of a small group of about 300 cells at the center of the presumptive eyespot, early during wing development, can completely inhibit development of the eyespot. The same group of cells can be transplanted to another region of the wing and induce ring-shaped pigment patterns in the host tissue around the graft. These findings show that a focus is a physiological entity. Color pattern induction is an intrinsic property of a small group of cells. Presumably these cells produce a factor that affects the production of enzymes involved in pigment synthesis.
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All butterfly and moth scales and bristles are made of non-living insect cuticle. Each is the product of a single epithelial cell, and all share the same basic architecture. However, some are highly specialized, and their cuticle is further elaborated into stacks of thin-films, lattices, or other minute structures, many of which first came to our attention because they interact with light to produce structural colors. The scale cell forms the scale by extruding a projection of itself and secreting around it the outer epicuticle, a thin cuticular envelope which will form the outer-most layer of the scale. The inner layers of cuticle, collectively called the procuticle, are secreted thereafter and go on to form the lattices, pillars, or other internal structures of the scale. We believe that the pattern-forming mechanisms used by the cell to shape the cuticle into its finished form include elastic buckling of the outer epicuticle to produce external folds, and "masking" of certain areas of the original epicuticular envelope to produce thin spots which will break through to become windows. Varied though they be, all insect cuticular patterns have common basic elements, which suggests that our findings may be generalized to other highly patterned insect cuticles, particularly those formed by single cells.
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