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Urticating setae of tarantulas (Araneae: Theraphosidae): Morphology, revision of typology and terminology and implications for taxonomy.

ABSTRACT: Tarantula urticating setae are modified setae located on the abdomen or pedipalps, which represent an effective defensive mechanism against vertebrate or invertebrate predators and intruders. They are also useful taxonomic tools as morphological characters facilitating the classification of New World theraphosid spiders. In the present study, the morphology of urticating setae was studied on 144 taxa of New World theraphosids, including ontogenetic stages in chosen species, except for species with urticating setae of type VII. The typology of urticating setae was revised, and types I, III and IV were redescribed. The urticating setae in spiders with type I setae, which were originally among type III or were considered setae of intermediate morphology between types I and III, are newly considered to be ontogenetic derivatives of type I and are described as subtypes. Setae of intermediate morphology between that of body setae and type II urticating setae that were found in Iridopelma hirsutum and Antillena rickwesti may provide another evidence that type II urticating setae evolved from body setae. It is supposed that the fusion of barbs with the shaft may lead to the morphology of type II setae. As the type II setae of Aviculariinae evolved independently to the UrS of Theraphosinae and both subfamilies represent two non-sister groups, this should explain the differences in the morphology of body setae in Aviculariinae and Theraphosinae. The terminology of "barbs" and "reversed barbs" was revised and redefined, newly emphasizing the real direction of barbs.

SUBMITTER: Kaderka R

PROVIDER: S-EPMC6844489 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Urticating setae of tarantulas (Araneae: Theraphosidae): Morphology, revision of typology and terminology and implications for taxonomy.

Kaderka Radan R Bulantová Jana J Heneberg Petr P Řezáč Milan M

PloS one 20191111 11

Tarantula urticating setae are modified setae located on the abdomen or pedipalps, which represent an effective defensive mechanism against vertebrate or invertebrate predators and intruders. They are also useful taxonomic tools as morphological characters facilitating the classification of New World theraphosid spiders. In the present study, the morphology of urticating setae was studied on 144 taxa of New World theraphosids, including ontogenetic stages in chosen species, except for species wi ...[more]

PMID: 31710616

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Project description:BackgroundThe primary objective of this study is to reconstruct the phylogeny of the hentzi species group and sister species in the North American tarantula genus, Aphonopelma, using a set of mitochondrial DNA markers that include the animal "barcoding gene". An mtDNA genealogy is used to consider questions regarding species boundary delimitation and to evaluate timing of divergence to infer historical biogeographic events that played a role in shaping the present-day diversity and distribution. We aimed to identify potential refugial locations, directionality of range expansion, and test whether A. hentzi post-glacial expansion fit a predicted time frame.Methods and findingsA Bayesian phylogenetic approach was used to analyze a 2051 base pair (bp) mtDNA data matrix comprising aligned fragments of the gene regions CO1 (1165 bp) and ND1-16S (886 bp). Multiple species delimitation techniques (DNA tree-based methods, a "barcode gap" using percent of pairwise sequence divergence (uncorrected p-distances), and the GMYC method) consistently recognized a number of divergent and genealogically exclusive groups.ConclusionsThe use of numerous species delimitation methods, in concert, provide an effective approach to dissecting species boundaries in this spider group; as well they seem to provide strong evidence for a number of nominal, previously undiscovered, and cryptic species. Our data also indicate that Pleistocene habitat fragmentation and subsequent range expansion events may have shaped contemporary phylogeographic patterns of Aphonopelma diversity in the southwestern United States, particularly for the A. hentzi species group. These findings indicate that future species delimitation approaches need to be analyzed in context of a number of factors, such as the sampling distribution, loci used, biogeographic history, breadth of morphological variation, ecological factors, and behavioral data, to make truly integrative decisions about what constitutes an evolutionary lineage recognized as a "species".

Project description:This systematic study documents the taxonomy, diversity, and distribution of the tarantula spider genus Aphonopelma Pocock, 1901 within the United States. By employing phylogenomic, morphological, and geospatial data, we evaluated all 55 nominal species in the United States to examine the evolutionary history of Aphonopelma and the group's taxonomy by implementing an integrative approach to species delimitation. Based on our analyses, we now recognize only 29 distinct species in the United States. We propose 33 new synonymies (Aphonopelma apacheum, Aphonopelma minchi, Aphonopelma rothi, Aphonopelma schmidti, Aphonopelma stahnkei = Aphonopelma chalcodes; Aphonopelma arnoldi = Aphonopelma armada; Aphonopelma behlei, Aphonopelma vogelae = Aphonopelma marxi; Aphonopelma breenei = Aphonopelma anax; Aphonopelma chambersi, Aphonopelma clarum, Aphonopelma cryptethum, Aphonopelma sandersoni, Aphonopelma sullivani = Aphonopelma eutylenum; Aphonopelma clarki, Aphonopelma coloradanum, Aphonopelma echinum, Aphonopelma gurleyi, Aphonopelma harlingenum, Aphonopelma odelli, Aphonopelma waconum, Aphonopelma wichitanum = Aphonopelma hentzi; Aphonopelma heterops = Aphonopelma moderatum; Aphonopelma jungi, Aphonopelma punzoi = Aphonopelma vorhiesi; Aphonopelma brunnius, Aphonopelma chamberlini, Aphonopelma iviei, Aphonopelma lithodomum, Aphonopelma smithi, Aphonopelma zionis = Aphonopelma iodius; Aphonopelma phanum, Aphonopelma reversum = Aphonopelma steindachneri), 14 new species (Aphonopelma atomicum sp. n., Aphonopelma catalina sp. n., Aphonopelma chiricahua sp. n., Aphonopelma icenoglei sp. n., Aphonopelma johnnycashi sp. n., Aphonopelma madera sp. n., Aphonopelma mareki sp. n., Aphonopelma moellendorfi sp. n., Aphonopelma parvum sp. n., Aphonopelma peloncillo sp. n., Aphonopelma prenticei sp. n., Aphonopelma saguaro sp. n., Aphonopelma superstitionense sp. n., and Aphonopelma xwalxwal sp. n.), and seven nomina dubia (Aphonopelma baergi, Aphonopelma cratium, Aphonopelma hollyi, Aphonopelma mordax, Aphonopelma radinum, Aphonopelma rusticum, Aphonopelma texense). Our proposed species tree based on Anchored Enrichment data delimits five major lineages: a monotypic group confined to California, a western group, an eastern group, a group primarily distributed in high-elevation areas, and a group that comprises several miniaturized species. Multiple species are distributed throughout two biodiversity hotspots in the United States (i.e., California Floristic Province and Madrean Pine-Oak Woodlands). Keys are provided for identification of both males and females. By conducting the most comprehensive sampling of a single theraphosid genus to date, this research significantly broadens the scope of prior molecular and morphological investigations, finally bringing a modern understanding of species delimitation in this dynamic and charismatic group of spiders.

Project description:BackgroundCITES is an international agreement between governments to ensure that international trade in specimens of wild animals and plants does not threaten their survival. Regarding spiders, all species listed in CITES are tarantulas. They are included in Appendix II, meaning that they are species that are not necessarily now threatened with extinction but that they may become so unless trade is closely controlled.Many tarantulas are legally and illegally traded in the pet market and they are one of the most traded invertebrate groups. Originally, the CITES list published in 1995 included all the current species of the genus Brachypelma Simon, 1891 plus Aphonopelma pallidum (F. O. Pickard-Cambridge, 1897) and the so-called Aphonopelma albiceps (Pocock, 1903). After that, some taxonomic changes were done, as well as descriptions of new species in the genus Brachypelma. The objective of this paper is to assess the 21 taxonomically valid spider species listed on CITES according to the IUCN criteria, study the general patterns and trends and advise on possible future conservation actions critical for the survival of endangered species.New informationAmongst all 21 species assessed, 16 had sufficient data on their distribution, ecology and threats to properly understand their current status and suggest possible conservation measures. A decline in the area of occupancy (AOO) and extent of occurrence (EOO) was inferred to almost all species, caused mostly by human activities (urbanisation, roads, agricultural and touristic activities), which often lead to the complete loss of subpopulations across their range. Hurricanes and frequent rising water, which are increasing in frequency due to climate change, can cause decline in habitat quality and consequent change in EOO and AOO of some species and should also be considered when planning conservation actions. Severe fragmentation was detected in 13 species and is therefore one of the most relevant threats to the most endangered Brachypelma species and should be made a priority aspect to deal with when proposing conservation actions for the group. Regarding the loss of individuals in wild populations, the main cause seems to be the overharvesting to meet the illegal trade.The most important conservation actions identified across species include preserving their natural habitat through protected areas, establishing management plans for both the species and their habitats and undertaking systematic monitoring to provide information about population recovery and species re-introduction programmes. In general, we propose to prioritise and support research on the population trends and distribution, as well as on the impact of land use and habitat degradation. Special attention regarding conservation actions and research plans has to be given to the central Pacific coastal area of Mexico, particularly around Guerrero State where five species of Brachypelma occur. Critically, for some of the most endangered species, such as B. baumgarteni and B. hamorii, there is no official protected area in their range of occurrence. It would therefore be highly recommended to establish at least one conservation unit which focuses on protecting each of these species in situ. In some cases, basic taxonomic research is needed before development of any appropriate conservation action can be proposed.

Project description:Background:The mechanics and energetics of spider locomotion have not been deeply investigated, despite their importance in the life of a spider. For example, the reproductive success of males of several species is dependent upon their ability to move from one area to another. The aim of this work was to describe gait patterns and analyze the gait parameters of Eupalaestrus weijenberghi (Araneae, Theraphosidae) in order to investigate the mechanics of their locomotion and the mechanisms by which they conserve energy while traversing different inclinations and surfaces. Methods:Tarantulas were collected and marked for kinematic analysis. Free displacements, both level and on an incline, were recorded using glass and Teflon as experimental surfaces. Body segments of the experimental animals were measured, weighed, and their center of mass was experimentally determined. Through reconstruction of the trajectories of the body segments, we were able to estimate their internal and external mechanical work and analyze their gait patterns. Results:Spiders mainly employed a walk-trot gait. Significant differences between the first two pairs and the second two pairs were detected. No significant differences were detected regarding the different planes or surfaces with respect to duty factor, time lags, stride frequency, and stride length. However, postural changes were observed on slippery surfaces. The mechanical work required for traversing a level plane was lower than expected. In all conditions, the external work, and within it the vertical work, accounted for almost all of the total mechanical work. The internal work was extremely low and did not rise as the gradient increased. Discussion:Our results support the idea of considering the eight limbs functionally divided into two quadrupeds in series. The anterior was composed of the first two pairs of limbs, which have an explorative and steering purpose and the posterior was more involved in supporting the weight of the body. The mechanical work to move one unit of mass a unit distance is almost constant among the different species tested. However, spiders showed lower values than expected. Minimizing the mechanical work could help to limit metabolic energy expenditure that, in small animals, is relatively very high. However, energy recovery due to inverted pendulum mechanics only accounts for only a small fraction of the energy saved. Adhesive setae present in the tarsal, scopulae, and claw tufts could contribute in different ways during different moments of the step cycle, compensating for part of the energetic cost on gradients which could also help to maintain constant gait parameters.

Dataset Information

Urticating setae of tarantulas (Araneae: Theraphosidae): Morphology, revision of typology and terminology and implications for taxonomy.

Publications

Urticating setae of tarantulas (Araneae: Theraphosidae): Morphology, revision of typology and terminology and implications for taxonomy.

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