Species delimitation and phylogeography of Aphonopelma hentzi (Araneae, Mygalomorphae, Theraphosidae): cryptic diversity in North American tarantulas

Background

The 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 Findings

A 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.

Conclusions

The 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”.     

Taxonomic revision of the tarantula genus Aphonopelma Pocock, 1901 (Araneae,Mygalomorphae, Theraphosidae) within the United States

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.     

Re-evaluating conservation priorities of New World tarantulas (Araneae: Theraphosidae) in a molecular framework indicates non-monophyly of the genera,Aphonopelma and Brachypelma

We present a mtDNA gene tree of tarantula spiders (Araneae: Mygalomorphae: Theraphosidae) based on the mitochondrial 16S-tRNA (leu)-ND1 gene region as a promising initial molecular hypothesis to clarify the taxonomy of the largest subfamily, Theraphosinae. Many species of this New World subfamily are traded widely as exotic pets, yet few scientific studies on them exist, and the robustness of many supposed taxonomic groupings is debatable. Yet the validity of taxon names and knowledge of their distinctiveness is vital for trade regulation, most notably for the Neotropical genus Brachypelma Simon 1891, which is listed under CITES (Appendix II, see online supplemental material, which is available from the article's Taylor & Francis Online page at https://doi.org/10.1080/14772000.2017.1346719). The use of molecular markers for tarantula taxonomy has been limited until recently, with most previous studies relying on morphological methods. Our findings, from newly collected molecular data, have several nomenclatural implications, suggesting a need for a rigorous overhaul of Theraphosinae classification at multiple hierarchical levels. Here, we take steps toward a revised classification, favouring division of Theraphosinae into three tribes: the Theraphosini trib. nov., the Hapalopini trib. nov., and the Grammostolini trib. nov. We also make conservation recommendations for two non-monophyletic genera. Firstly, we recover Aphonopelma Pocock 1901 as polyphyletic, finding that the large radiation into the USA and Mexico is taxonomically distinct from at least three other lineages distributed throughout Central America, one of which includes the type species of the genus. Secondly, and importantly for conservation, we find diphyly in the CITES listed genus Brachypelma Simon 1891, where our data strongly favour a division into two distinct smaller genera. We consider only the lineage with endemics in the Pacific coastal zone of Mexico to be of conservation concern. Finally, we also make suggestions on the future direction of revisionary research for the Theraphosidae as a whole.

http://zoobank.org/urn:lsid:zoobank.org:pub:B37F7795-3F92-4334-A0C7-65C8026EE1FB     

Three new species of Melloleitaoina Gerschman & Schiapelli, 1960 (Araneae,Mygalomorphae, Theraphosidae) from northern Argentina

Three new species of the monotypic genus Melloleitaoina Gerschman & Schiapelli, 1960 are described from northern Argentina: M. mutquina sp. n., M. uru sp. n. and M. yupanqui sp. n. The female specimen originally described as M. crassifemur is not conspecific with the male holotype and thus is removed from this species and described as M. uru sp. n.; M. crassifemur is redescribed. All species are diagnosed, illustrated and a key to species is provided.     

An integrative approach for species delimitation in the spider genus Grammostola (Theraphosidae,Mygalomorphae)

The mygalomorph genus Grammostola (family Theraphosidae) is endemic to South America. The species Grammostola anthracina is one of the largest spiders in Uruguay and reputed to be the longest lived tarantula in the world. This nominal species has two distinct colour morphs comprising black and reddish‐brown forms with controversial taxonomic status. Here, we present a phylogenetic study based on molecular characters (cytochrome c oxidase subunit I) of haplotypes of G. anthracina and closely related species. Our analysis together with new morphological data and biogeographical information indicates that the two morphs of G. anthracina constitute different species that are not sister to each other. Consequently, a new species, Grammostola quirogai is described, diagnosed and illustrated to encompass the black morph. Phylogenetic relationships and new taxonomic characters for Grammostola species included in this study are discussed.     

The reproductive period of tarantulas is constrained by their thermal preferences (Araneae,Theraphosidae)

Locomotor and physiological performance of ectotherms are affected by temperature. Thermoregulation is achieved by changes in behavior and the selection of micro-habitats with adequate temperatures to maintain the body temperature (T_b) within a range of preference. Apart from this temperature dependence at spatial scales, ectotherms are also affected by temperature at temporal scale. For instance, ectotherms can only be active some months of the year, particularly in temperate environments. Tarantulas are ectotherms that live in burrows most of their life. Nevertheless, after the sexual maturation molt, males leave their refugia and start a wandering life searching for females to mate. The reproductive period varies among species. In some species walking males are seen in late spring or early summer, while in other species males are only seen during fall or winter. Apart from the differences in lifestyles after maturation, tarantulas exhibit sexual dimorphisms in longevity and body mass, having smaller, shorter-lived males. Thus, to optimize energetic budgets, decreasing thermoregulation costs, we hypothesize and examine a putative correlation between an individual's preferred body temperature (T_pref) and the environmental temperature during the reproductive period. Hence, we characterize T_pref in seven tarantula species and analyze which factors (i.e., time of day, body mass, and sex) correlated with it. Furthermore, we assess putative correlated evolution of T_pref with ambient temperature (minima, mean, and maxima) during the reproductive period by means of phylogenetic independent contrasts. We did not find differences in thermal preferences between sexes; and only one species, Acanthoscurria suina, exhibited diel differences in T_pref. We found evidence of correlated evolution between T_pref and minimum temperature during the reproductive period among all seven species studied herein. Our results show that the reproductive period is constrained by thermal preferences, dictating when males can start their wandering life to mate.     

Energy metabolism and the postprandial response of the Chilean tarantulas, Euathlus truculentus (Araneae: Theraphosidae)

One of the most ubiquitous consequences of feeding in animals is specific dynamic action (SDA), a drastic increment in metabolic rate after a meal, which lasts from a few hours to several days. According to a recent exhaustive review by Secor (2009), studies in SDA are abundant, encompassing all kinds of vertebrates and invertebrates. However, important exceptions are arachnids, as few studies have characterized SDA in this group. Here, we measured the standard metabolic rate (SMR) of the Chilean tarantulas Euathlus truculentus (body mass=7.32±0.7 g; N=32; T(A)=25°C), its inter-individual variation (i.e., repeatability) and its SDA. We measured SMR three or four times in each individual, and we also conducted predation experiments where a prey was consumed by each spider, during a respirometry trial. The SMR of E. truculentus was 0.00049±0.000079 mlCO(2) g(-1) min(-1) which corresponds to 1524 μW (assuming a protein-based diet), 108.4% of the predicted value for arachnids. According to the standard nomenclature for SDA studies, the scope of the SDA for a meal size of 1.26±0.04 g (18% of the spider size) was 6.55±1.1 times the baseline, the time to peak was 45 min, and the magnitude of the SDA was 0.28±0.03 kj, which is 85% of the expected value for invertebrates. Our SMR data are in concordance with previous findings suggesting remarkably low energy metabolism in arachnids, compared with other arthropods. On the other hand, the exceedingly high scope of the postprandial response contrasts with the comparatively low SDA. This fact suggests that spiders spend most of the energy for digestion in a short period after prey capture, which could be a consequence of their external digestion.     

Theraphosidae phylogeny: relationships of the ‘Ischnocolinae’ genera (Araneae,Mygalomorphae)

The mygalomorph spider subfamily ‘Ischnocolinae’ was originally established as a group based on the presence of divided tarsal scopula. Later, the divided condition of the scopula was considered the plesiomorphic state, which could not support the monophyly of ‘Ischnocolinae’. In Raven 1985, the subfamily was considered paraphyletic, pending a phylogenetic analysis to reinvestigate monophyletic groups. This study comprises such a phylogenetic analysis, based on morphological data, that includes representatives of all genera currently included in ‘Ischnocolinae’ as well as representatives of all other nine Theraphosidae subfamilies (Thrigmopoeinae, Ornithoctoninae, Eumenophorinae, Stromatopelminae, Harpactirinae, Selenogyrinae, Theraphosinae, Aviculariinae and Selenocosmiinae). The family Theraphosidae is considered monophyletic and expanded to include three additional genera previously considered as possible Barychelidae, namely Brachionopus (as Harpactirinae), Trichopelma and Reichlingia (as Ischnocolinae sensu stricto) while ‘Ischnocolinae’ as previously defined does not appear as monophyletic. However, two monophyletic groups were defined as subfamilies to include some former ‘Ischnocolinae’ representatives. The first group includes Acanthopelma rufescens, Trichopelma nitidum, Reichlingia annae, Ischnocolus spp., Holothele rondoni, Holothele culebrae and Holothele aff culebrae and is hereby named as Ischnocolinae (sensu stricto). The other subgroup comprises Sickius longibulbi, Holothele incei, Holothele aff incei, Guyruita spp., Schismatothele lineata, Hemiercus modestus, Holothele colonica and Holothele sp., together established as Schismatothelinae subfam. nov. Several genera included in former ‘Ischnocolinae’ appear as monophyletic (Catumiri, Oligoxystre, Heterothele, Nesiergus, Chaetopelma, Ischnocolus, Guyruita and Plesiophrictus). However, the genera Holothele, Schismatothele and Hemiercus deserve more attention in order to evaluate their intrarelationships and inclusion of species.     

Three new species of Euathlus Ausserer, 1875 (Araneae,Theraphosidae) from Argentina

ABSTRACT

Euathlus

Ausserer, 1875 is a South American genus of spiders of the family Theraphosidae known from Chile and Argentina. Three new species from Argentina: Euathlus mauryi sp. n. (from San Juan province), Euathlus grismadoi sp. n. (from La Rioja province), and Euathlus pampa sp. n. (from Salta province) are described here. New records of the previous species Euathlus diamante and Euathlus tenebrarum are contributed. The distribution of these new species expands the geographical distribution of the genus along the Andean hills, with Salta province as the northernmost record of the genus. A key is provided for identification of Euathlus species as well as a map with all the records in Argentina.     

Testing species boundaries in the Antrodiaetus unicolor complex (Araneae: Mygalomorphae: Antrodiaetidae): "paraphyly" and cryptic diversity

The inability to correctly identify species has far reaching implications in nearly all areas of biology, yet few studies investigate methods for delineating species boundaries. Moreover, once these boundaries have been hypothesized, little thought has been given to how these constructs can be further evaluated. We employ a molecular phylogenetic approach using nuclear 28S rRNA and mitochondrial cytochrome c oxidase subunit I genes to test the general efficacy of species boundaries in the Antrodiaetus unicolor spider species complex. Our analyses provide evidence that An. unicolor is "paraphyletic" with respect to An. microunicolor, indicating that morphological criteria used to delineate species boundaries undersplits actual species-level diversity in this group of spiders. These analyses also demonstrate that individuals from geographically proximate populations sometimes exhibit considerable molecular divergence, strongly suggesting that An. unicolor is a cryptic species complex. Finally, this molecular approach has provided the phylogenetic framework that is necessary to begin interpreting the vast amount of morphological variation observed in these spiders based upon findings from previous studies. Our approach using multiple genes appears to be a rigorous method to critically examine species boundaries originally based on traditional morphological approaches to spider taxonomy.     

A new species of the genus Chaetopelma Ausserer, 1871 (Araneae: Theraphosidae) from Turkey

A new species of Chaetopelma Ausserer, 1871 is described from Hatay province, Turkey. Differences between the new species and related species are discussed. The characteristic features of this species are described and illustrated.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:99C21605-5308-4363-8420-02F6151B4457     

Four new Mouse Spider species (Araneae,Mygalomorphae, Actinopodidae,Missulena) from Western Australia

Four new species of the Mouse Spider genus Missulena Walckenaer, 1805 (family Actinopodidae) are described from Western Australia based on morphological features of adult males. Missulena leniae sp. n.(from the Carnarvon and Yalgoo biogeographic regions), Missulena mainae sp. n. (Carnarvon), Missulena melissae sp. n. (Pilbara) and Missulena pinguipes sp. n. (Mallee) represent a broad spectrum of morphological diversity found in this genus and differ from other congeners by details of the male copulatory bulb, colour patterns, eye sizes, leg morphology and leg spination. Two of the species, M. pinguipes sp. n. and M. mainae sp. n., are characterised by swollen metatarsi of the fourth legs in males, a feature not previously recorded in the family. A key to males of all named Missulena species from Australia is presented and allows their identification based on external morphology.     

Two Trichosporon species isolated from Central-European mygalomorph spiders (Araneae: Mygalomorphae)

Trichosporon (Dikarya: Basidiomycota) is a genus of anamorphic yeasts typically associated with soil and water, although many species are causative agents of diseases in animals and man. Here we provide the first compelling evidence that spiders can be occasionally colonized by at least two Trichosporon species. Trichosporon dulcitum (Berkhout) Weijman 1979 was isolated from the exoskeleton of purse-web spider Atypus piceus, while Trichosporon porosum (Stautz) Middelhoven, Scorzetti & Fell 2001 was isolated from the exoskeleton of purse-web spider Atypus affinis. Both of the species were identified based on DNA sequence analysis of the host specimens displaying macroscopic signs of the superficial white mycosis on their exoskeleton. Only two specimens with macroscopic signs of superficial yeast growth were identified among the 125 individuals of A. affinis, A. piceus and Atypus muralis examined that were collected at various sites throughout the Czech Republic. The consistent burrow microclimate, uninterrupted occupancy of the single burrow for several subsequent years, and presence of prey remnants in the burrow below the purse-web may play a role in the course of infection of the mygalomorphs examined. The phylogenetic relationships of Trichosporon species are analyzed, concluding that association with invertebrates clusters predominantly among four groups of closely related species in independent Trichosporon clades.     

Two new species of Chaco Tullgren from the Atlantic coast of Uruguay (Araneae,Mygalomorphae, Nemesiidae)

We describe two new species of the nemesiid spider genus Chaco from Rocha Province, Uruguay. These new species are diagnosed based on genital morphology, male tibial apophysis spination, and burrow entrance. We test cospecificity of one species, Chaco costai,via laboratory mating experiments. The new species are diagnosed and illustrated and habitat characteristics, and capture behavior are described. We conduct a cladistic analysis based on a previously published morphological character matrix that now includes the newly described species.     

Factors affecting lifespan in bird-eating spiders (Arachnida: Mygalomorphae,Theraphosidae) – A multi-species approach

Lifespan is a life-history trait being of utmost importance, as it is frequently closely related to individual fitness. However, interspecific comparisons are relatively rare, being hampered by the high effort to collect longevity data across taxa. We here compiled lifespan data for 85 species of bird-eating spiders (Theraphosidae) held in captivity, based on 2183 individual records from the animal record books of both zoological gardens of Berlin, Germany. Using a data-mining approach we sought for broad patterns of correlations between lifespan and an array of other variables as derived from the literature. We found that the subfamily Eumenophoriinae lived on average longest, followed by the Theraphosinae, Ornithoctinae, Grammostolinae, Selenocosmiinae, Ischnocolinae and finally the Avicularinae. Species inhabiting tropical, more humid and/or low-altitude environments lived longer, suggesting that more predictable environments facilitate the evolution of longer lifespans. Furthermore, large range size, low abundance, sub-terrestrial life-style, and aggressive behavior were all associated with longer lifespans. Evidence for resource allocation trade-offs was revealed as larger spiderling and prosoma size was negatively related to longevity. Our rather rough approach revealed several patterns worth of future investigations, and illustrate the value of zoo records for interspecific comparisons.     

Factors affecting lifespan in bird-eating spiders (Arachnida: Mygalomorphae,Theraphosidae) – A multi-species approach

Lifespan is a life-history trait being of utmost importance, as it is frequently closely related to individual fitness. However, interspecific comparisons are relatively rare, being hampered by the high effort to collect longevity data across taxa. We here compiled lifespan data for 85 species of bird-eating spiders (Theraphosidae) held in captivity, based on 2183 individual records from the animal record books of both zoological gardens of Berlin, Germany. Using a data-mining approach we sought for broad patterns of correlations between lifespan and an array of other variables as derived from the literature. We found that the subfamily Eumenophoriinae lived on average longest, followed by the Theraphosinae, Ornithoctinae, Grammostolinae, Selenocosmiinae, Ischnocolinae and finally the Avicularinae. Species inhabiting tropical, more humid and/or low-altitude environments lived longer, suggesting that more predictable environments facilitate the evolution of longer lifespans. Furthermore, large range size, low abundance, sub-terrestrial life-style, and aggressive behavior were all associated with longer lifespans. Evidence for resource allocation trade-offs was revealed as larger spiderling and prosoma size was negatively related to longevity. Our rather rough approach revealed several patterns worth of future investigations, and illustrate the value of zoo records for interspecific comparisons.     

Two new species of Phoridae (Diptera) whose larvae associate with large spiders (Araneae: Theraphosidae)

Two new species of Megaselia Rondani, M. dinwrphica Disney and M. praedafura Disney, are described from South America. Their larvae crawl around on the bodies and exuviae of Theraphosidae. Larvae of M. praedafura were observed moving on to the spider's prey while it was engaged in feeding from the same prey.     

Antimicrobial activity of the toxin VdTX-I from the spider Vitalius dubius (Araneae,Theraphosidae)

BackgroundCurrently there is an urgent need to develop new classes of antimicrobial agents with different mechanisms of action from conventionally antibiotics used for the control of pathogenic microorganisms. The acylpolyamine called VdTX-I was isolated from the venom of the tarantula Vitalius dubius, and first described with activity as an antagonist of nicotinic cholinergic receptors. The main objective of this study was to investigate the antimicrobial activity found in the venom of the spider, with emphasis on the toxin VdTX-I.MethodsAntimicrobial assays were performed in 96 well plates culture against 14 micro-organisms (fungi, yeasts and bacteria), which were tested concentrations from 0.19 to 100 μM of VdTX-I. After qualitative analysis, dose-response curve assays were performed in bacterial kill curve using MTT reagent and hemolytic assay.ResultsThe antimicrobial activity of the VdTX-I toxin was observed in 12 tested species of Candida, Trichosporiun, Staphylococcus and Micrococcus. The toxicity had a dose-response at 3.12 µM – 100 μM in Candida albicans, Candida guillermondii, Micrococcus luteus and Escherichia coli. VdTX-I took about 5 min to inhibit bacterial growth, which was faster than streptomycin. The toxin showed no hemolytic activity between 0.19 and 100 μM. At 2.5 µg/mL of toxin it was observed no growth inhibition against a mammalian cell lineage.ConclusionsThe VdTX-I toxin has a significant antimicrobial activity, with broad spectrum, and is experimentally inert to mammalian blood cells.General SignificanceThis paper explores the antimicrobial potential of the spider toxin VdTX-I, which can provide a new model to design new antimicrobial drugs.     

Hydraulic lift among native plant species in the Mojave Desert

Hydraulic lift was investigated among native plants in the Mojave Desert using in situ thermocouple psychrometers. Night lighting and day shading experiments were used to verify the phenomenon. Hydraulic lift was detected for all species examined: five shrub species with different rooting depths and leaf phenologies and one perennial grass species. This study was the first to document hydraulic lift for a CAM species, Yucca schidigera. The pattern of diel flux in soil water potential for the CAM species was temporally opposite to that of C₃ species: for the CAM plant, soil water potential increased in shallow soils during the day when the plant was not transpiring and decreased at night when transpiration began. Because CAM plants transport water to shallow soils during the day when surrounding C₃ and C₄ plants transpire, CAM species that hydraulically lift water may influence water relations of surrounding species to a greater extent than hydraulically lifting C₃ or C₄ species. A strong, negative relationship between the percent sand in the study site soils at the 0.35 m soil depth and the frequency that hydraulic lift was observed at that depth suggests that the occurrence of hydraulic lift is negatively influenced by coarse-textured soils, perhaps due to less root–soil contact in sandy soils relative to finer-textured soils. Differences in soil texture among study sites may explain, in part, differences in the frequency that hydraulic lift was detected among these species. Further investigations are needed to elucidate species versus soil texture effects on hydraulic lift. This revised version was published online in June 2006 with corrections to the Cover Date.