RESUMO
Vicariance and dispersal events, combined with intricate global climatic history, have left an imprint on the spatiotemporal distribution and diversity of many organisms. Anelosimus cobweb spiders (Theridiidae), are organisms ranging in behavior from solitary to highly social, with a cosmopolitan distribution in temperate to tropical areas. Their evolutionary history and the discontinuous distribution of species richness suggest that 1) long-distance overwater dispersal and 2) climate change during the Neogene (23-2.6 Ma), may be major factors in explaining their distribution and diversification. Here, we test these hypotheses, and explicitly test if global Miocene/Pliocene climatic cooling in the last 8 Ma affected Anelosimus radiation in parallel in South America and Madagascar. To do so, we investigate the phylogeny and spatiotemporal biogeography of Anelosimus through a culmination of a 20-year comprehensive global sampling at the species level (69 species, including 84% of the known 75 species worldwide, represented by 268 individuals) using nucleotide data from seven loci (5.5 kb). Our results strongly support the monophyly of Anelosimus with an Oligocene ($\sim $30 Ma) South American origin. Major clades on other continents originate via multiple, long-distance dispersal events, of solitary or subsocial-but not social-lineages, from the Americas. These intercontinental dispersals were to Africa, Madagascar (twice), and SE Asia/Australasia. The early diversification of Anelosimus spiders coincides with a sudden thermal increase in the late Oligocene ($\sim $27-25 Ma), though no causal connection can be made. Our results, however, strongly support the hypothesis that global Neogene climatic cooling in the last 8 Ma drove Anelosimus radiation in parallel in South America and Madagascar, offering a rare empirical evidence for diversification of a socially diverse group driven by an interplay between long-distance dispersal and global Neogene climatic changes. [Cobweb spiders; diversification; global biogeography; long-distance dispersal; molecular phylogenetics; neogene climate changes; sociality; vicariance.].
Assuntos
Distribuição Animal/fisiologia , Biodiversidade , Filogenia , Aranhas/classificação , Aranhas/fisiologia , Animais , Mudança ClimáticaRESUMO
Adult body size, development time, and growth rates are components of organismal life histories, which crucially influence fitness and are subject to trade-offs. If selection is sex-specific, male and female developments can eventually lead to different optimal sizes. This can be achieved through developmental plasticity and sex-specific developmental trajectories. Spiders present suitable animals to study differences in developmental plasticity and life history trade-offs between the sexes, because of their pronounced sexual dimorphism. Here, we examine variation in life histories in the extremely sexually size dimorphic African hermit spider (Nephilingis cruentata) reared under standardized laboratory conditions. Females average 70 times greater body mass (and greater body size) at maturity than males, which they achieve by developing longer and growing faster. We find a small to moderate amount of variability in life history traits to be caused by family effects, comprising genetic, maternal, and early common environmental effects, suggesting considerable plasticity in life histories. Remarkably, family effects explain a higher variance in male compared to female life histories, implying that female developmental trajectories may be more responsive to environment. We also find sex differences in life history trade-offs and show that males with longer development times grow larger but exhibit shorter adult longevity. Female developmental time also correlates positively with adult body mass, but the trade-offs between female adult mass, reproduction, and longevity are less clear. We discuss the implications of these findings in the light of evolutionary trade-offs between life history traits.
Assuntos
Características de História de Vida , Aranhas , Animais , Evolução Biológica , Feminino , Masculino , Reprodução , Caracteres SexuaisRESUMO
Specialized predators possess a variety of adaptations. In venomous predators, this may include the size of the venom gland and venom composition. It is expected that due to different foraging strategies, predators with a wide trophic niche (generalists) should possess larger venom glands that contain more diversified components than predators with a narrow niche (specialists). We focused on spiders, as the most diversified group of venomous predators, in which a wide variety of trophic strategies have evolved. We conducted a comparative analysis using 40 spider species, in which we measured the size of their venom gland and venom complexity using proteome profiling methods. The species were classified into three trophic groups: generalists, facultative specialists and obligatory specialists. We found that the venom glands of generalists are larger than those of obligatory specialists, which is presumably due to more frequent prey capture by the former. The complexity of venom of peptides (2-15 kDa) and proteins (15-250 kDa) was more diverse in generalists than in specialists. Multivariate analysis of venom revealed significant differences among the three trophic categories only in the complexity of peptides. Our study thus shows that venom gland size and its content have taken different pathways during the evolution of different trophic strategies in spiders. Generalists evolved larger venom glands with more complex composition, whereas obligatory specialists possess smaller glands with less diverse chemical structures.
Assuntos
Evolução Biológica , Proteoma/química , Venenos de Aranha/química , Aranhas/anatomia & histologia , Aranhas/classificação , Animais , FilogeniaRESUMO
The morphologically uniform suborder Cyphophthalmi represents a basal group of harvestmen (Opiliones). As such, it plays an important role in the reconstruction of the karyotype evolution within this arachnid order. The cytogenetic analysis of 6 representatives of the suborder Cyphophthalmi, namely Miopsalis sp. (2n = 30; Stylocellidae), Austropurcellia arcticosa (Cantrell, 1980) (2n = 30; Pettalidae), Parapurcellia amatola de Bivort & Giribet, 2010 (2n = 32; Pettalidae), Paramiopsalis aff. ramulosus Juberthie, 1962 (2n = 28; Sironidae), Cyphophthalmus duricorius Joseph, 1868 (2n = 24; Sironidae), and Siro carpaticus Rafalski, 1956 (2n = 52; Sironidae) was performed. Fluorescence in situ hybridization with 18S rDNA probe was used to analyze the distribution of major ribosomal RNA genes in harvestmen. We confront the obtained cytogenetic data with current hypotheses on cyphophthalmid phylogeny to reconstruct their karyotype evolution. We conclude that the ancestral karyotype of harvestmen consisted of 2n = 30 elements with 1 chromosome pair bearing terminal rDNA clusters. The rDNA locus was multiplicated in the evolution of Cyphophthalmi. However, decreases as well as increases in the number of chromosomes have been detected in the karyotype evolution of Cyphophthalmi. Our data thus reveal unexpected diversity in cyphophthalmid karyotypes.
Assuntos
Aracnídeos/classificação , Aracnídeos/genética , Evolução Molecular , Cariótipo , Animais , Feminino , Hibridização in Situ Fluorescente , Masculino , Filogenia , RNA Ribossômico 18S/genéticaRESUMO
As part of a revision of the Afrotropical species of Trachelas L. Koch, 1872 (Araneae: Trachelidae), we distinguished three new genera of primarily arboreal spiders from southern Africa that are described here: Coronarachne gen. nov., represented by four new species known from both sexes, C. denticulata sp. nov. (type species), C. penicillus sp. nov., C. setosa sp. nov. and C. unigena sp. nov., and C. neethlingi sp. nov., known only from the male; Falcaranea gen. nov., represented by three new species known from both sexes, F. amatola sp. nov., F. gladius sp. nov. (type species) and F. maputensis sp. nov.; and Trachecymbius gen. nov., represented by five new species, T. bosselaersi sp. nov. (), T. felis sp. nov. (), T. peterwebbi sp. nov. (), T. tyume sp. nov. (type species, ), and T. umbella sp. nov. (). These three genera share the presence of strongly protruding setal bases on the ventral surfaces of the anterior legs, which are more strongly developed in males and can be mistaken for small ventral cusps that are found in several trachelid genera. Identification keys are provided for each of the three genera and their phylogenetic affinities to other Afrotropical Trachelidae are evaluated based on the cytochrome oxidase c subunit I (COI) gene. Most of the species described here were common in canopy fogging samples, and to a lesser extent beating, but are clearly a prominent component of the arboreal trachelid fauna in savanna and forest habitats in southern Africa.
Assuntos
Aranhas , Feminino , Masculino , Animais , Filogenia , África Austral , Ecossistema , Florestas , Distribuição AnimalRESUMO
The Afrotropical sac spider genus Messapus Simon, 1898, presently placed in the Castianeirinae, is reviewed. The type material of the type species, M. martini Simon, 1898, clearly represents two different species, a corinnine female (here designated the lectotype) and a castianeirine male (the paralectotype). The female is redescribed and its corresponding male is described for the first time. As a result, Messapus is transferred to the Corinninae. Corinna natalis Pocock, 1898 is transferred to Messapus, while Messapus secundus Strand, 1907 is transferred to Merenius Simon, 1909. The new genus Copuetta gen. nov., with the type species C. maputa sp. nov., is established to accommodate the misidentified castianeirine male paralectotype of M. martini, and its matching female is described for the first time. Castianeira kibonotensis Lessert, 1921 syn. nov. is considered a junior synonym of Copuetta lacustris (Strand, 1916) comb. nov., which is redescribed from both sexes and transferred from Copa Simon, 1885. A further eleven new species of Copuetta are described: C. comorica sp. nov., C. erecta sp. nov., C. kakamega sp. nov., C. kwamgumi sp. nov., C. lesnei sp. nov., C. litipo sp. nov., C. lotzi sp. nov., C. magna sp. nov., C. naja sp. nov., C. uzungwa sp. nov. and C. wagneri sp. nov. Of these species, only C. lacustris and C. magna sp. nov. have large distribution ranges. Seven of the species are only known from the type locality and the remaining four have distributions restricted to one or two countries. A second new genus, Wasaka gen. nov., is described for four new species with restricted distributions from East and Central Africa: W. imitatrix sp. nov., W. montana sp. nov., W. occulta sp. nov. (type species) and W. ventralis sp. nov. A first phylogenetic analysis focused on the Afrotropical Castianeirinae is presented. The results support the placement and transfer of Messapus (including M. natalis comb. nov.) and Medmassa Simon, 1887 in the Corinninae, and the monophyly of a clade including the four cryptic lycosiform castianeirine genera from the Afrotropical Region (Copa, Copuetta gen. nov., Echinax Deeleman-Reinhold, 2001 and Wasaka gen. nov.). The implications of the phylogenetic results are briefly discussed.
Assuntos
Aranhas/classificação , Distribuição Animal , Estruturas Animais/anatomia & histologia , Estruturas Animais/crescimento & desenvolvimento , Animais , Tamanho Corporal , Feminino , Quênia , Masculino , Montana , Tamanho do Órgão , Filogenia , Aranhas/anatomia & histologia , Aranhas/genética , Aranhas/crescimento & desenvolvimentoRESUMO
The spider genus Castanilla Caporiacco, 1936 is presently represented by two species, C. quinquemaculata Caporiacco, 1936 (type species) and C. marchesii Caporiacco, 1936, both described from Libya. The genus has never been revised and neither of the two species have ever been redescribed (Platnick 2013). The placement of the genus has up to now also been rather uncertain. Caporiacco (1936a,b) described and placed its two species in the Clubionidae, Reiskind (1969) placed it in Clubionidae: Castianeirinae, and it is currently included in the Corinnidae (Platnick 2013).
Assuntos
Aranhas/classificação , Distribuição Animal , Estruturas Animais/anatomia & histologia , Animais , Ecossistema , Feminino , Líbia , Masculino , Aranhas/anatomia & histologiaRESUMO
The ground spider genera Leptodrassex Murphy, 2007 and Leptopilos Levy, 2009 are recorded from southern Africa for the first time, with the description of five new species: Leptodrassex murphyi sp. nov. (â â) from Mozambique and South Africa, and L. capensis sp. nov. (â) from South Africa; Leptopilos butleri sp. nov. (â â) and L. vasivulva sp. nov. (â â) from Botswana, South Africa and Zimbabwe, and L. digitus sp. nov. (â â) from South Africa. Further, the new genus Afrodrassex gen. nov. is described, with the type species A. balrog sp. nov. (â â) from South Africa and Angola, and A. catharinae sp. nov. (â â) from South Africa described therein. Details of the somatic and genitalic morphology of all three genera are examined by scanning electron microscopy, and revised descriptions of Leptodrassex and Leptopilos are presented.
Assuntos
Aranhas , Animais , África AustralRESUMO
The continental Afrotropical species of the spider genus Orthobula Simon, 1897 are revised. The three currently known species, O. calceata Simon, 1897 (West Africa and western Congo Basin), O. milloti Caporiacco, 1949 (Kenya) and O. radiata Simon, 1897 (southern Africa), are redescribed, including the first descriptions of the males of O. calceata and females of O. radiata. Three new species are described from both sexes: O. aethiopica sp. nov. from Ethiopia, O. arca sp. nov. from South Africa, and O. marusiki sp. nov. from West Africa and the western Congo Basin. All of the species are obligate ground-dwellers, being particularly common in the leaf litter of woody plants, except for O. arca sp. nov., which prefers open grasslands.
Assuntos
Aranhas , Distribuição Animal , Estruturas Animais , Animais , Feminino , Masculino , Tamanho do ÓrgãoRESUMO
Myrmecomorphy is the most frequent type of Batesian mimicry. Myrmecomorphic species differ in the accuracy with which they resemble ants; however, the hypothesis of the co-evolution of mimetic traits has been rarely tested. Here, we measured dozens of traits of color, shape, size, and behavior, and quantified objectively the resemblance between dozens of arthropod mimics and ants. In all traits, the mimics were more similar to ants than to closely related non-myrmecomorphic species. We found that mimics resemble ants mainly in color and behavior, and less in size and body shape. We found that the mimetic accuracy in four trait categories demonstrate divergent co-evolutionary patterns. Mimetic accuracy in color was positively correlated with shape and size in insects but negatively in spiders, presumably reflecting developmental constraints. Accuracy in shape tend to be negatively related to movement in both insects and spiders supporting the motion-limited discrimination hypothesis.
RESUMO
The genus Carteronius Simon, 1897 is transferred from Clubionidae to Corinnidae and recognized as the senior synonym of Mandaneta Strand, 1932, being the oldest available name for the pre-occupied Mandane Karsch, 1880. Upon comparing the respective type specimens, the type species of Carteronius and the type species of Mandaneta were found to represent the same species. Whence the type species Carteronius helluo Simon, 1896, is considered a junior synonym of the type species Mandaneta sudana (Karsch, 1880). Three other species of Carteronius are transferred to Donuea Strand, 1932 (Corinnidae): D. fuscus (Simon, 1896) comb. nov. from Mauritius, D. vittiger (Simon, 1896) comb. nov. and D. argenticomus (Keyserling, 1877) comb. nov., both from Madagascar. The type species, Carteronius sudanus comb. nov., from Côte d'Ivoire, Democratic Republic of the Congo, Ghana, Guinea, Sierra Leone, and C. gentilis (Simon, 1909) comb. nov., from Equatorial Guinea and Cameroon (the latter transferred from Procopius Thorell, 1899) are redescribed, and the female of C. gentilis is described for the first time. Six new species of Carteronius are described: C. ashanti Bonaldo & Silva-Junior sp. nov. from Ghana, C. myene Bonaldo & Labarque sp. nov., and C. simoni Bonaldo & Shimano sp. nov. from Gabon, C. lumumba Bonaldo & Ramírez sp. nov. from Cameroon, Gabon and the Democratic Republic of the Congo, and C. arboreus Bonaldo & Haddad sp. nov. and C. teke Bonaldo & Bosselaers sp. nov. from the Democratic Republic of the Congo. A key and distribution maps to all eight species in the genus are presented. The related Bunyoronius Bonaldo, Ramírez & Haddad gen. nov. is proposed to include B. femoralis Bonaldo, Ramírez & Haddad sp. nov. from the Central African Republic, Uganda, and Rwanda.
Assuntos
Aranhas , Feminino , Animais , Distribuição AnimalRESUMO
In the internet era, the digital architecture that keeps us connected and informed may also amplify the spread of misinformation. This problem is gaining global attention, as evidence accumulates that misinformation may interfere with democratic processes and undermine collective responses to environmental and health crises1,2. In an increasingly polluted information ecosystem, understanding the factors underlying the generation and spread of misinformation is becoming a pressing scientific and societal challenge3. Here, we studied the global spread of (mis-)information on spiders using a high-resolution global database of online newspaper articles on spider-human interactions, covering stories of spider-human encounters and biting events published from 2010-20204. We found that 47% of articles contained errors and 43% were sensationalist. Moreover, we show that the flow of spider-related news occurs within a highly interconnected global network and provide evidence that sensationalism is a key factor underlying the spread of misinformation.
Assuntos
Mídias Sociais , Aranhas , Animais , Comunicação , Ecossistema , Humanos , Aranhas/fisiologiaRESUMO
Mass media plays an important role in the construction and circulation of risk perception associated with animals. Widely feared groups such as spiders frequently end up in the spotlight of traditional and social media. We compiled an expert-curated global database on the online newspaper coverage of human-spider encounters over the past ten years (2010-2020). This database includes information about the location of each human-spider encounter reported in the news article and a quantitative characterisation of the content-location, presence of photographs of spiders and bites, number and type of errors, consultation of experts, and a subjective assessment of sensationalism. In total, we collected 5348 unique news articles from 81 countries in 40 languages. The database refers to 211 identified and unidentified spider species and 2644 unique human-spider encounters (1121 bites and 147 as deadly bites). To facilitate data reuse, we explain the main caveats that need to be made when analysing this database and discuss research ideas and questions that can be explored with it.
Assuntos
Picada de Aranha , Venenos de Aranha , Aranhas , Animais , Bases de Dados Factuais , Humanos , Idioma , Jornais como AssuntoRESUMO
The genus Micaria Westring, 1851 (Araneae, Gnaphosidae) is a group of small (1.85-5 mm) ant-like spiders that can be distinguished from other gnaphosids by their piriform gland spigots that are similar in size to the major ampullate gland spigots. According to the World Spider Catalog, there are 105 species of Micaria in the world, of which only three species are known from the African part of the Afrotropical Region, namely M. chrysis (Simon, 1910), M. tersissima Simon, 1910 and M. beaufortia (Tucker, 1923). The objectives of this study were to revise Micaria in the Afrotropical Region, providing new and updated records for each of the species, evaluating the relationships between them using COI barcoding data, and providing information on their biology, mimetic relationships and feeding ecology. These objectives were met by collecting fresh material from the KwaZulu-Natal, Western Cape, Northern Cape and Free State provinces in South Africa. Fresh material of M. tersissima and M. chrysis were collected from their type localities, Komaggas and Port Nolloth (Northern Cape Province), respectively, for identification and DNA analyses. COI sequences generated, together with those sourced from Barcode of Life Data Systems (BOLD) and GenBank, were aligned using the CulstalW alignment algorithm in the Mega X software, and molecular phylogenetic analyses were performed using MrBayes for Bayesian Inference (BI) and RaxML for maximum likelihood (ML) analyses. Morphological examination of the collected and voucher material yielded 17 new species for the Afrotropical Region, namely M. basaliducta sp. nov. (â, â, South Africa), M. bimaculata sp. nov. (â, â, Mauritania), M. bispicula sp. nov. (â, â, Namibia, South Africa), M. durbana sp. nov. (â, â, South Africa, Zambia), M. felix sp. nov. (â, â, Cameroon, Ethiopia, Malawi, Mozambique, Namibia, South Africa, Zambia, Zimbabwe), M. gagnoa sp. nov. (â, â, Côte d'Ivoire, Mozambique, Mozambique, Tanzania), M. koingnaas sp. nov. (â, South Africa), M. lata sp. nov. (â, Namibia, South Africa), M. laxa sp. nov. (â, South Africa), M. mediospina sp. nov. (â, South Africa), M. parvotibialis sp. nov. (â, â, Senegal), M. plana sp. nov. (â, â, Ethiopia), M. quadrata sp. nov. (â, Ethiopia), M. quinquemaculosa sp. nov. (â, â, Namibia, South Africa), M. rivonosy sp. nov. (â, â, Madagascar), M. sanipass sp. nov. (â, South Africa) and M. scutellata sp. nov. (â, South Africa). Furthermore, both sexes of M. beaufortia, as well as the male of M. tersissima, are redescribed. Both sexes of M. chrysis are described for the first time, as this species was only known from a juvenile. Of the previously known species, M. beaufortia (Botswana, Ethiopia, Lesotho, Namibia, South Africa, Zimbabwe) and M. chrysis (Côte d'Ivoire, Ethiopia, Lesotho, Namibia, South Africa, Tanzania) are widespread in the Afroptropics, while M. tersissima is only known from South Africa. Both the Bayesian inference and the maximum likelihood analysess recovered Micaria (sensu lato) as monophyletic with the inclusion of the subopaca group. The pulicaria species group was recovered as polyphyletic in both the BI and ML analyses. Four Afrotropical species, as well as the M. rossica Thorell, 1875/M. foxi Gertsch, 1933 group, formed a clade sister to M. formicaria (Sundevall, 1831). Eight of the Afrotropical species now have COI barcoding data uploaded to BOLD.
Assuntos
Aranhas , Distribuição Animal , Animais , Teorema de Bayes , Feminino , Masculino , Filogenia , África do Sul , Aranhas/genéticaRESUMO
A new genus of the spider family Trachelidae L. Koch, 1872 from the Afrotropical Region is described. Capobula gen. nov. is represented by five species, known from South Africa and Lesotho only. Adults of both sexes of Orthobula infima Simon, 1896a, which is widely distributed in the Western Cape, South Africa, are described for the first time, and this species is transferred to Capobula gen. nov. as its type species. Four new species are described: C. capensis spec. nov. and C. neethlingi spec. nov. (South Africa: Western Cape), C. montana spec. nov. (Lesotho and South Africa: Eastern Cape, Free State and KwaZulu-Natal) and C. ukhahlamba spec. nov. (South Africa: KwaZulu-Natal). A phylogenetic analysis based on the cytochrome oxidase subunit I (COI) gene, including 14 genera of Trachelidae, one genus of Clubionidae Wagner, 1887 and three genera of Phrurolithidae Banks, 1892, supports the placement of Capobula gen. nov. in Trachelidae, with Orthobula Simon, 1897 as its likely closest relative.
Assuntos
Aranhas , Distribuição Animal , Animais , Feminino , Masculino , Filogenia , África do Sul , Aranhas/genéticaRESUMO
Zootaxa published more than a thousand papers on Araneae from 2002 to the present, including descriptions of 3,833 new spider species and 177 new genera. Here we summarise the key contributions of Zootaxa to our current knowledge of global spider diversity. We provide a historical account of the researchers that have actively participated as editors, and recognize the more than 1,000 reviewers without whom none of this would have been possible. We conduct a simple analysis of the contributions by authors and geographic region, which allows us to uncover some of the underlying trends in current spider taxonomy. In addition, we examine some of the milestones in twenty years of spider systematic research in Zootaxa. Finally, we discuss future prospects of spider taxonomy and the role that Zootaxa and its younger sister journal Megataxa will play in it. We would like to dedicate this contribution to the memory of Norman I. Platnick, a crucial figure in the advancement of spider systematics.
Assuntos
Aranhas/classificação , Animais , Biodiversidade , Publicações Periódicas como AssuntoRESUMO
BACKGROUND: Despite progress in genomic analysis of spiders, their chromosome evolution is not satisfactorily understood. Most information on spider chromosomes concerns the most diversified clade, entelegyne araneomorphs. Other clades are far less studied. Our study focused on haplogyne araneomorphs, which are remarkable for their unusual sex chromosome systems and for the co-evolution of sex chromosomes and nucleolus organizer regions (NORs); some haplogynes exhibit holokinetic chromosomes. To trace the karyotype evolution of haplogynes on the family level, we analysed the number and morphology of chromosomes, sex chromosomes, NORs, and meiosis in pholcids, which are among the most diverse haplogyne families. The evolution of spider NORs is largely unknown. RESULTS: Our study is based on an extensive set of species representing all major pholcid clades. Pholcids exhibit a low 2n and predominance of biarmed chromosomes, which are typical haplogyne features. Sex chromosomes and NOR patterns of pholcids are diversified. We revealed six sex chromosome systems in pholcids (X0, XY, X1X20, X1X2X30, X1X2Y, and X1X2X3X4Y). The number of NOR loci ranges from one to nine. In some clades, NORs are also found on sex chromosomes. CONCLUSIONS: The evolution of cytogenetic characters was largely derived from character mapping on a recently published molecular phylogeny of the family. Based on an extensive set of species and mapping of their characters, numerous conclusions regarding the karyotype evolution of pholcids and spiders can be drawn. Our results suggest frequent autosome-autosome and autosome-sex chromosome rearrangements during pholcid evolution. Such events have previously been attributed to the reproductive isolation of species. The peculiar X1X2Y system is probably ancestral for haplogynes. Chromosomes of the X1X2Y system differ considerably in their pattern of evolution. In some pholcid clades, the X1X2Y system has transformed into the X1X20 or XY systems, and subsequently into the X0 system. The X1X2X30 system of Smeringopus pallidus probably arose from the X1X20 system by an X chromosome fission. The X1X2X3X4Y system of Kambiwa probably evolved from the X1X2Y system by integration of a chromosome pair. Nucleolus organizer regions have frequently expanded on sex chromosomes, most probably by ectopic recombination. Our data suggest the involvement of sex chromosome-linked NORs in achiasmatic pairing.
Assuntos
Aranhas , Animais , Cariótipo , Cariotipagem , Meiose/genética , Cromossomos Sexuais/genética , Aranhas/genéticaRESUMO
Penestomine spiders were first described from females only and placed in the family Eresidae. Discovery of the male decades later brought surprises, especially in the morphology of the male pedipalp, which features (among other things) a retrolateral tibial apophysis (RTA). The presence of an RTA is synapomorphic for a large clade of spiders exclusive of Eresidae. A molecular data matrix based on four loci was constructed to test two alternative hypotheses: (1) penestomines are eresids and the RTA is convergent, or (2) penestomines belong within the RTA clade. Taxon sampling concentrated on the Eresidae and the RTA clade, especially outside of the Dionycha and Lycosoidea. Evolution of the cribellum, conventionally characterized as a primitive araneomorph spinning organ lost multiple times, is explored. Parsimony optimization indicates repeated appearances of the cribellum. Exploration of asymmetric rates of loss and gain in both a likelihood framework and using a Sankoff matrix under parsimony reveals that cribellum homology is supported when losses are two times more likely than gains. We suggest that when complicated characters appear (under parsimony optimization) to evolve multiple times, investigators should consider alternative reconstructions featuring a relatively high rate of loss. Evolution of other morphological characters is also investigated. The results imply revised circumscription of some RTA-clade families, including Agelenidae, Amaurobiidae, Cybaeidae, Dictynidae and Hahniidae. Some nomenclatural changes are formally proposed here; others await further investigation. The family Penestomidae (NEW RANK) is established. Tamgrinia, not Neoramia, is the cribellate sister clade of the ecribellate Agelenidae. Tamgrinia and the subfamily Coelotinae are transferred from the family Amaurobiidae to the family Agelenidae. Zanomys and its relatives are not coelotines but belong to a clade tentatively identified as Macrobuninae.
Assuntos
Evolução Molecular , Filogenia , Aranhas/classificação , Animais , Teorema de Bayes , Feminino , Funções Verossimilhança , Masculino , Modelos Genéticos , RNA Ribossômico 18S/genética , RNA Ribossômico 28S/genética , Alinhamento de Sequência , Análise de Sequência de DNA , Aranhas/anatomia & histologia , Aranhas/genéticaRESUMO
The jumping spider tribe Ballini is reviewed in the Afrotropical Region. The genera Afromarengo Benjamin, 2004 and Goleta Peckham Peckham, 1894 are redefined. In Afromarengo, A. coriacea (Simon, 1900) is illustrated and A. ghanaensis sp. nov. (â, from Ghana) and A. ugandensis sp. nov. (ââ, from Uganda and D.R. Congo) are newly described. For Goleta, the type species, Goleta workmani (Peckham Peckham, 1885), is redescribed from both sexes. Seven new genera and twelve new species are described, including three monotypic genera, Ballagascar gen. nov., with B. insularis (Peckham Peckham, 1885) comb. nov. (ex Colaxes Simon, 1900) from Madagascar (ââ) as the type species; Mondeku gen. nov., with M. albopilosum sp. nov. (ââ, from Kenya) as the type species; and Oviballus gen. nov., with O. vidae sp. nov. (ââ, from South Africa) as the type species. We also describe Planamarengo gen. nov., with P. bimaculata (Peckham Peckham, 1903) comb. nov. (ex Afromarengo) from South Africa (ââ) as the type species, as well as P. gatamaiyu sp. nov. (â, from Kenya) and P. kenyaensis sp. nov. (ââ, from Kenya); Propiomarengo gen. nov., with P. plana (Haddad Wesolowska, 2013) comb. nov. (ex Afromarengo) from South Africa (â) as the type species, as well as P. foordi sp. nov. (â, from South Africa); Tenuiballus gen. nov., with T. minor sp. nov. (â, from South Africa) as the type species, and also including T. coronatus sp. nov. (â, from South Africa); and Wandawe gen. nov., with W. benjamini (Wesolowska Haddad, 2013) comb. n. (ex Colaxes) from South Africa (ââ) as the type species, and also including W. australe sp. nov. (ââ, from South Africa) and W. tigrinа sp. nov. (ââ, from Kenya and Uganda). A new combination for Copocrossa albozonata Caporiacco, 1949, Afromarengo albozonata comb. nov. is provided, and the name A. albozonata is treated as a nomen dubium. A new species of Padilla Peckham Peckham, 1894, a genus only known from the Afrotropical Indian Ocean islands, P. wandae sp. nov. (ââ, from Madagascar), is described. New data and illustrations for Sadies Wanless, 1984, as well as two Asian species of Colaxes, are provided. The recently revised Pachyballus Simon, 1900 and Peplometus Simon, 1900 are not treated further. A key to the genera of Afrotropical Ballinae is presented, as well as new data on their natural history, biogeography, and a discussion of the evolution of mimicry of various arthropod groups by balline jumping spiders. A putative synapomorphy and the new composition of Ballini sensu novo are proposed.
Assuntos
Aranhas , Distribuição Animal , Estruturas Animais , Animais , Tamanho Corporal , Feminino , Masculino , Tamanho do ÓrgãoRESUMO
Two new trachelid spiders were collected from Guangxi, southern China, and are described here as Utivarachna subfabaria sp. nov. (â, â) and U. tangi sp. nov. (â). Both species belong to the Utivarachna kinabaluensis-group. Detailed generic synapomorphies are deduced based on an assessment of all known Utivarachna species, and an updated key to the Utivarachna species from China is provided.