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Sample records for dyspnoid harvestman paranemastoma

  1. Penis morphology in a Burmese amber harvestman

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    Dunlop, Jason A.; Selden, Paul A.; Giribet, Gonzalo

    2016-02-01

    A unique specimen of the fossil harvestman Halitherses grimaldii Giribet and Dunlop, 2005 (Arachnida: Opiliones) from the Cretaceous (ca. 99 Ma) Burmese amber of Myanmar reveals a fully extended penis. This is the first record of a male copulatory organ of this nature preserved in amber and is of special importance due to the age of the deposit. The penis has a slender, distally flattened truncus, a spatulate heart-shaped glans and a short distal stylus, twisted at the tip. In living harvestmen, the penis yields crucial characters for their systematics. Male genital morphology in H. grimaldii appears to be unique among the wider Dyspnoi clade to which this fossil belongs. The large eyes in the fossil differ markedly from other members of the subfamily Ortholasmatinae to which H. grimaldii was originally referred. Based on recent data, it has been argued that large eyes may be plesiomorphic for Palpatores (i.e. the suborders Eupnoi and Dyspnoi), potentially rendering this character plesiomorphic for the fossil too. Thus, the unique structure of the penis seen here, and the probable lack of diaphanous teeth, present in all other extant non-acropsopilionid Dyspnoi, suggest that H. grimaldii represents a new, extinct family of large-eyed dyspnoid harvestmen, Halithersidae fam. nov.; a higher taxon in amber diagnosed here on both somatic and genital characters.

  2. The first fossil cyphophthalmid harvestman from Baltic amber

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    Dunlop, Jason A.

    2011-01-01

    Full Text Available The first fossil cyphophthalmid harvestman (Opiliones: Cyphophthalmi from Palaeogene (Eocene Baltic amber is described. This is only the third fossil example of this basal harvestman lineage; the others being from the probably slightly younger Bitterfeld amber and the much older, early Cretaceous, Myanmar (Burmese amber. Although incomplete and lacking most of the appendages, the new Baltic amber fossil can be identified as a female. The somatic characters preserved, especially spiracle morphology and the coxo-genital region, allow it to be assigned with some confidence to the extant genus Siro Latreille, 1796 (Sironidae. This fossil is formally described here as Siro balticus sp. nov. It resembles modern North American Siro species more than modern European ones, and can be distinguished principally on its relatively large size and the outline form of the body.

  3. Paecilaema batman, a new species of Brazilian troglophilous harvestman that exhibits a remarkable color patches variation (Opiliones: Cosmetidae

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    Ricardo Pinto-da-Rocha

    2013-08-01

    Full Text Available A new species of harvestman, Paecilaema batman, from Brazilian limestone caves of the state of Goiás, is described, and a remarkable intraspecific color patch variation is discussed. Paecilaema batman sp. nov. differs from other species of the genus by the following combination of features: chelicera similar in both sexes; prosoma without color patches; typical color patches on area I; and area III with two high spines. The new species is considered troglophilous.

  4. A new highly specialized cave harvestman from Brazil and the first blind species of the genus: Iandumoema smeagol sp. n. (Arachnida, Opiliones, Gonyleptidae)

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    Pinto-da-Rocha, Ricardo; da Fonseca-Ferreira, Rafael; Bichuette, Maria Elina

    2015-01-01

    Abstract A new species of troglobitic harvestman, Iandumoema smeagol sp. n., is described from Toca do Geraldo, Monjolos municipality, Minas Gerais state, Brazil. Iandumoema smeagol sp. n. is distinguished from the other two species of the genus by four exclusive characteristics – dorsal scutum areas with conspicuous tubercles, enlarged retrolateral spiniform tubercle on the distal third of femur IV, eyes absent and the penial ventral process slender and of approximately the same length of the stylus. The species is the most highly modified in the genus and its distribution is restricted only to caves in that particular area of Minas Gerais state. The type locality is not inside a legally protected area, and there are anthropogenic impacts in its surroundings. Therefore, Iandumoema smeagol sp. n. is vulnerable and it must be considered in future conservation projects. PMID:26798238

  5. The disjunct pattern of the Neotropical harvestman Discocyrtus dilatatus (Gonyleptidae explained by climate-driven range shifts in the Quaternary: Paleodistributional and molecular evidence.

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    Julia Vergara

    Full Text Available The disjunct distribution of the harvestman Discocyrtus dilatatus (Opiliones, Gonyleptidae is used as a case study to test the hypothesis of a trans-Chaco Pleistocene paleobridge during range expansion stages. This would have temporarily connected humid regions ('Mesopotamia' in northeastern Argentina, and the 'Yungas' in the northwest, NWA in the subtropical and temperate South American lowlands. The present study combines two independent approaches: paleodistributional reconstruction, using the Species Distribution Modeling method MaxEnt and projection onto Quaternary paleoclimates (6 kya, 21 kya, 130 kya, and phylogeographic analyses based on the cytochrome oxidase subunit I molecular marker. Models predict a maximal shrinkage during the warm Last Interglacial (130 kya, and the rise of the hypothesized paleobridge in the Last Glacial Maximum (21 kya, revealing that cold-dry stages (not warm-humid ones, as supposed enabled the range expansion of this species. The disjunction was formed in the mid-Holocene (6 kya and is intensified under current conditions. The median-joining network shows that NWA haplotypes are peripherally related to different Mesopotamian lineages; haplotypes from Santa Fe and Córdoba Provinces consistently occupy central positions in the network. According to the dated phylogeny, Mesopotamia-NWA expansion events would have occurred in the last glacial period, in many cases closely associated to the Last Glacial Maximum, with most divergence events occurring shortly thereafter. Only two (out of nine NWA haplotypes are shared with Mesopotamian localities. A single, presumably relictual NWA haplotype was found to have diverged much earlier, suggesting an ancient expansion event not recoverable by the paleodistributional models. Different measures of sequence statistics, genetic diversity, population structure and history of demographic changes are provided. This research offers the first available evidence for the historical

  6. First experimental evidence that a harvestman (Arachnida: Opiliones detects odors of non-rotten dead prey by olfaction

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    Thaiany Miranda Costa

    2013-06-01

    Full Text Available Harvestmen feed on live, dead and fresh, or decomposing animals, fungi, and plant matter, being very dependent on chemoreception to find food. Herein we performed an experiment to test if individuals of Discocyrtus pectinifemur Mello-Leitão, 1937 (Gonyleptidae (n = 23 behave differently when in contact with olfactory cues from different sources (rotten prey, non-rotten prey and a control. Using dead crickets in a box covered with a mesh, and recording the time the harvestmen spent in the vicinities of the box, we show that D. pectinifemur detects non-rotten prey and stays longer on it than on the other two treatments. Our results contrast with a previous study on another species, showing that we should not generalize results obtained for one species. Our data also suggest that olfactory receptors occur on the legs of these harvestmen and that D. pectinifemur might choose dietary items based on olfaction.

  7. 77 FR 7175 - Endangered and Threatened Species Permit Applications

    Science.gov (United States)

    2012-02-10

    ...: Wildlife World Zoo, Litchfield Park, Arizona. Applicant requests an amendment to a current permit for... following species within Texas: Bee Creek Cave harvestman (Texella reddelli) Bone Cave harvestman (Texella...

  8. A multilocus phylogeny of Podoctidae (Arachnida, Opiliones, Laniatores) and parametric shape analysis reveal the disutility of subfamilial nomenclature in armored harvestman systematics

    Czech Academy of Sciences Publication Activity Database

    Sharma, P. P.; Santiago, M. A.; Kriebel, R.; Lipps, S. M.; Buenavente, P. A. C.; Diesmos, A. C.; Janda, Milan; Boyer, S. L.; Clouse, R. M.; Wheeler, W. C.

    2017-01-01

    Roč. 106, JAN 01 (2017), s. 164-173 ISSN 1055-7903 Institutional support: RVO:60077344 Keywords : grassatores * morphology * comparative methods Subject RIV: EG - Zoology OBOR OECD: Zoology Impact factor: 4.419, year: 2016 http://www.sciencedirect.com/science/article/pii/S1055790316302445

  9. 78 FR 75369 - Endangered and Threatened Species Permit Applications

    Science.gov (United States)

    2013-12-11

    ... into the wild in Oklahoma. Permit TE-833851 Applicant: City of Austin Watershed Protection Department... reddelli) Black-capped vireo (Vireo atricapilla) Bone Cave harvestman (Texella reyesi) Braken Bat Cave...

  10. 75 FR 13299 - Lower Colorado River Authority Transmission Services Corporation; Construction, Operation...

    Science.gov (United States)

    2010-03-19

    ... and recovery of the species in the wild; and (5) the measures, if any, we require as necessary or... water snake, Clear Creek gambusia, sharpnose shiner, smalleye shiner, Bee Creek Cave harvestman, Texas... alternatives on other resources such as vegetation, wetlands, wildlife, geology and soils, air quality, water...

  11. Endemic harvestmen and spiders of Austria (Arachnida: Opiliones, Araneae

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    Komposch, Christian

    2011-01-01

    Full Text Available A comprehensive overview of plant, fungus and animal species of Austria revealed a total of 748 endemic and subendemic species, including, 11 harvestman and 46 spider species. Altogether two endemic harvestmen (Nemastoma bidentatum relictum, Nemastoma schuelleri and 8 endemic spiders (Abacoproeces molestus, Collinsia (caliginosa nemenziana, Mughiphantes severus, Mughiphantes styriacus, Pelecopsis alpica, Scotophaeus nanus, Troglohyphantes novicordis, Troglohyphantes tauriscus, beside 9 subendemic harvestman and 38 subendemic spider species have been recorded from Austria. Hot-spots of endemism in the Eastern Alps are the north-eastern (Ennstaler Alps and southern Calcareous Alps (Karawanken, Karnische Alps and the Central Alps (Hohe Tauern, Gurktaler Alps, Ötztaler and Stubaier Alps. Most of the endemic arachnid species occur from the nival down to the montane zone. Important habitats are rocky areas, caves and woodlands. High absolute numbers and percentages of endemics can be found within the harvestman families Cladonychiidae, Ischyropsalididae and Nemastomatidae and in the spider genera Lepthyphantes s. l. and Troglohyphantes. The conservation status of these highly endangered taxa – 85 % of the spider species and 100 % of the harvestman taxa are endangered in Austria – is poor.

  12. Das Höhlenlangbein Amilenus aurantiacus (Opiliones: Phalangiidae ist Höhlentier des Jahres 2016 in Deutschland

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    Zaenker, Stefan

    2016-09-01

    Full Text Available With the nomination of the ‘Cave Animal of the Year’ the Society of German Cave and Karst Explorers calls public and authorities’ attention to the understudied biodiversity of subterranean ecosystems. Here the Cave Animal of the Year 2016, Amilenus aurantiacus (Simon, 1881, is presented. It is the first time that a harvestman has been chosen. Ist ecology, habitat and morphology are described. New records from Hesse, Bavaria, Baden-Württemberg and North Rhine-Westphalia are listed and discussed.

  13. Egg Production Constrains Chemical Defenses in a Neotropical Arachnid.

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    Taís M Nazareth

    Full Text Available Female investment in large eggs increases the demand for fatty acids, which are allocated for yolk production. Since the biosynthetic pathway leading to fatty acids uses the same precursors used in the formation of polyketides, allocation trade-offs are expected to emerge. Therefore, egg production should constrain the investment in chemical defenses based on polyketides, such as benzoquinones. We tested this hypothesis using the harvestman Acutiosoma longipes, which produces large eggs and releases benzoquinones as chemical defense. We predicted that the amount of secretion released by ovigerous females (OFs would be smaller than that of non-ovigerous females (NOF. We also conducted a series of bioassays in the field and in the laboratory to test whether egg production renders OFs more vulnerable to predation. OFs produce less secretion than NOFs, which is congruent with the hypothesis that egg production constrains the investment in chemical defenses. Results of the bioassays show that the secretion released by OFs is less effective in deterring potential predators (ants and spiders than the secretion released by NOFs. In conclusion, females allocate resources to chemical defenses in a way that preserves a primary biological function related to reproduction. However, the trade-off between egg and secretion production makes OFs vulnerable to predators. We suggest that egg production is a critical moment in the life of harvestman females, representing perhaps the highest cost of reproduction in the group.

  14. Evolutionary and biogeographical history of an ancient and global group of arachnids (Arachnida: Opiliones: Cyphophthalmi) with a new taxonomic arrangement

    DEFF Research Database (Denmark)

    Giribet, Gonzalo; Sharma, Prashant P.; Benavides, Ligia R.

    2012-01-01

    We investigate the phylogeny, biogeography, time of origin and diversification, ancestral area reconstruction and large-scale distributional patterns of an ancient group of arachnids, the harvestman suborder Cyphophthalmi. Analysis of molecular and morphological data allow us to propose a new......; Boreophthalmi includes Stylocellidae and Sironidae, the latter family of questionable monophyly. The internal resolution of each family is discussed and traced back to its geological time origin, as well as to its original landmass, using methods for estimating divergence times and ancestral area reconstruction....... The origin of Cyphophthalmi can be traced back to the Carboniferous, whereas the diversification time of most families ranges between the Carboniferous and the Jurassic, with the exception of Troglosironidae, whose current diversity originates in the Cretaceous/Tertiary. Ancestral area reconstruction...

  15. Wie viele Arten von Milbenkankern (Opiliones, Cyphophthalmi gibt es in Österreich?

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    Raspotnig, Günther

    2011-07-01

    Full Text Available For the last 60 years, the mite-harvestman Cyphophthalmus duricorius Joseph, 1868, a soil-dwelling sironid, has been considered to be the only representative of the opilionid suborder Cyphophthalmi in Austria. However, novel data from recent collections confirm the presence of at least two further Austrian cyphophthalmid species. (1 Siro cf. crassus Novak & Giribet, 2006 occurs in at least one location in SW Styria near the Slovenian border and hence represents a member of a second genus of Austrian sironids. (2 A further morphologically distinct sironid (“Sironidae gen. et sp. nov.?” – so far undescribed and systematically not placed in detail – was collected in the borderland between Styria and Carinthia. All three species can be found in a small area of a few square-kilometers; although no syntopic occurrence was recorded.

  16. A new species of Leiobunum from Arizona, U. S. A. highlights the limits of typological classification in harvestmen (Opiliones: Sclerosomatidae: Leiobuninae).

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    Shultz, Jeffrey W

    2018-01-09

    A new species of leiobunine harvestman from the Chiricahua Mountains of Arizona is described. The species lacks pro- and retrolateral submarginal rows of coxal denticles, a feature often considered diagnostic for the polyphyletic Nelima, and has greatly reduced ventral dentition on the palpal claw, as in the monotypic Leuronychus. In most other respects, the species is uniquely similar to members of a clade from central and western Mexico currently in the poly- and/or paraphyletic Leiobunum. These traits include a supracheliceral lamina with a wide transverse plate and a canaliculate ocularium, with an anterior surface that slopes dorsoposteriorly and a posterior surface that bulges rearward and is constricted at its base.  There is thus a conflict between classification using traditional diagnostic characters and classification using unique similarity of non-traditional characters. The problem is exacerbated by the problematic status of each candidate genus. Here the species is placed in Leiobunum as L. silum sp. nov., a decision that gives weight to probable phylogenetic affinity with species currently placed in that genus. Leiobunum silum provides an excellent example of the limits of traditional typological classification and the need for a broad-scale morphological and molecular revision of sclerosomatid harvestmen.

  17. Terrestrial invertebrates in the Rhynie chert ecosystem.

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    Dunlop, Jason A; Garwood, Russell J

    2018-02-05

    The Early Devonian Rhynie and Windyfield cherts remain a key locality for understanding early life and ecology on land. They host the oldest unequivocal nematode worm (Nematoda), which may also offer the earliest evidence for herbivory via plant parasitism. The trigonotarbids (Arachnida: Trigonotarbida) preserve the oldest book lungs and were probably predators that practiced liquid feeding. The oldest mites (Arachnida: Acariformes) are represented by taxa which include mycophages and predators on nematodes today. The earliest harvestman (Arachnida: Opiliones) includes the first preserved tracheae, and male and female genitalia. Myriapods are represented by a scutigeromorph centipede (Chilopoda: Scutigeromorpha), probably a cursorial predator on the substrate, and a putative millipede (Diplopoda). The oldest springtails (Hexapoda: Collembola) were probably mycophages, and another hexapod of uncertain affinities preserves a gut infill of phytodebris. The first true insects (Hexapoda: Insecta) are represented by a species known from chewing (non-carnivorous?) mandibles. Coprolites also provide insights into diet, and we challenge previous assumptions that several taxa were spore-feeders. Rhynie appears to preserve a largely intact community of terrestrial animals, although some expected groups are absent. The known fossils are (ecologically) consistent with at least part of the fauna found around modern Icelandic hot springs.This article is part of a discussion meeting issue 'The Rhynie cherts: our earliest terrestrial ecosystem revisited'. © 2017 The Author(s).

  18. Chromosome complement and meiosis of Holmbergiana weyenberghii (Opiliones: Sclerosomatidae: Gagrellinae from Argentina Complemento cromosómico y meiosis de Holmbergiana weyenberghii (Opiliones: Sclerosomatidae: Gagrellinae de Argentina

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    Sergio G. Rodríguez Gil

    2010-12-01

    Full Text Available The cytogenetical analysis of the harvestman Holmbergiana weyenberghii (Holmberg (Eupnoi, Sclerosomatidae, Gagrellinae from Argentina is reported for the first time. The complement of males is composed of 18 chromosomes. In meiosis there are nine homomorphic bivalents: one large, five medium-sized and three small. The chromosome number of H. weyenberghii is within the range of diploid numbers of the subfamily Gagrellinae Thorell, which shows the lowest chromosome numbers among the sclerosomatids.Se analiza citogenéticamente, por primera vez, una especie de opilión proveniente de Argentina: Holmbergiana weyenberghii (Holmberg (Eupnoi, Sclerosomatidae, Gagrellinae. Los machos tienen un complemento cromosómico compuesto por 18 cromosomas. En meiosis, hay nueve bivalentes homomórficos: uno mayor, cinco medianos y tres menores. El número cromosómico de H. weyenberghii se encuentra dentro del rango de números diploides de los Gagrellinae Thorell; esta subfamilia presenta los números cromosómicos más bajos de Sclerosomatidae.

  19. Alarm communication: a new function for the scent-gland secretion in harvestmen (Arachnida: Opiliones)

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    Machado, Glauco; Bonato, Vinícius; Oliveira, Paulo

    2002-05-01

    Most harvestmen are nocturnal, nonacoustical, and nonvisual arthropods. They have a pair of exocrine glands on the cephalothorax that produce defensive volatile secretions. We investigated in the field the possible alarm effect of these secretions in the gregarious harvestman Goniosoma aff. proximum. A cotton swab soaked with the species' own exudate (treatment), or with water (control), was held 1-2 cm from the center of harvestmen aggregations. The results showed that the gland secretion elicits an alarm response in Goniosoma: whereas 73.3% of the aggregations dispersed after being stimulated with the gland exudate, only 3.3% responded to the water control. Respondent groups are larger than non-respondent groups, and the time of reaction to the secretion was inversely related to group size. This is the first demonstration of a chemically-mediated alarm effect in harvestmen. The alarm response in gregarious harvestmen has possibly evolved as a by-product of a primarily defensive reaction in the context of predator avoidance. The discovery of this novel function of scent-gland secretion is meaningful in view of the widespread occurrence of gregarious habit among species of the order Opiliones.

  20. Light from dark: A relictual troglobite reveals a broader ancestral distribution for kimulid harvestmen (Opiliones: Laniatores: Kimulidae) in South America

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    Ceccarelli, F. Sara; Monte, Bruno G. O.; Proud, Daniel N.; DaSilva, Márcio Bernardino; Bichuette, Maria E.

    2017-01-01

    A new troglobitic harvestman, Relictopiolus galadriel gen. nov et sp. nov., is described from Olhos d’Água cave, Itacarambi, Minas Gerais State, Brazil. Morphological characters, including male genitalia and exomorphology, suggest that this species belongs to the family Kimulidae, and it appears to share the greatest similarities with Tegipiolus pachypus. Bayesian inference analyses of a molecular dataset strongly support the inclusion of this species in Kimulidae and confirm the hypothesized sister-group relationship between R. galadriel and T. pachypus. A time calibrated phylogeny indicates that these sister-taxa diverged from a common ancestor approximately 40 Mya, during the Paleogene. The current range of Kimulidae illustrates a remarkable disjunct distribution, and leads us to hypothesize that the ancestral distribution of Kimulidae was once much more widespread across eastern Brazil. This may be attributed to the Eocene radiation associated with the warming (and humidifying) events in the Cenozoic when the best conditions for evergreen tropical vegetation in South America were established and followed by the extinction of kimulid epigean populations together with the retraction of rain forests during the Oligocene to Miocene cooling. The discovery of this relictual troglobite indicates that the Olhos d’Água cave was a stable refugium for this ancient lineage of kimulids and acted as a "museum" of biodiversity. Our findings, considered collectively with the diverse troglofauna of the Olhos d’Água cave, highlight it as one of the most important hotspots of troglobite diversity and endemism in the Neotropics. Given the ecological stresses on this habitat, the cavernicolous fauna are at risk of extinction and we emphasize the urgent need for appropriate conservation actions. Finally, we propose the transfer of Acanthominua, Euminua, Euminuoides and Pseudominua from Kimulidae to Zalmoxidae, resulting in two new synonymies and 13 new combinations. PMID

  1. Paternal care decreases foraging activity and body condition, but does not impose survival costs to caring males in a Neotropical arachnid.

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    Requena, Gustavo S; Buzatto, Bruno A; Martins, Eduardo G; Machado, Glauco

    2012-01-01

    Exclusive paternal care is the rarest form of parental investment in nature and theory predicts that the maintenance of this behavior depends on the balance between costs and benefits to males. Our goal was to assess costs of paternal care in the harvestman Iporangaia pustulosa, for which the benefits of this behavior in terms of egg survival have already been demonstrated. We evaluated energetic costs and mortality risks associated to paternal egg-guarding in the field. We quantified foraging activity of males and estimated how their body condition is influenced by the duration of the caring period. Additionally, we conducted a one-year capture-mark-recapture study and estimated apparent survival probabilities of caring and non-caring males to assess potential survival costs of paternal care. Our results indicate that caring males forage less frequently than non-caring individuals (males and females) and that their body condition deteriorates over the course of the caring period. Thus, males willing to guard eggs may provide to females a fitness-enhancing gift of cost-free care of their offspring. Caring males, however, did not show lower survival probabilities when compared to both non-caring males and females. Reduction in mortality risks as a result of remaining stationary, combined with the benefits of improving egg survival, may have played an important and previously unsuspected role favoring the evolution of paternal care. Moreover, males exhibiting paternal care could also provide an honest signal of their quality as offspring defenders, and thus female preference for caring males could be responsible for maintaining the trait.

  2. Paternal care decreases foraging activity and body condition, but does not impose survival costs to caring males in a Neotropical arachnid.

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    Gustavo S Requena

    Full Text Available Exclusive paternal care is the rarest form of parental investment in nature and theory predicts that the maintenance of this behavior depends on the balance between costs and benefits to males. Our goal was to assess costs of paternal care in the harvestman Iporangaia pustulosa, for which the benefits of this behavior in terms of egg survival have already been demonstrated. We evaluated energetic costs and mortality risks associated to paternal egg-guarding in the field. We quantified foraging activity of males and estimated how their body condition is influenced by the duration of the caring period. Additionally, we conducted a one-year capture-mark-recapture study and estimated apparent survival probabilities of caring and non-caring males to assess potential survival costs of paternal care. Our results indicate that caring males forage less frequently than non-caring individuals (males and females and that their body condition deteriorates over the course of the caring period. Thus, males willing to guard eggs may provide to females a fitness-enhancing gift of cost-free care of their offspring. Caring males, however, did not show lower survival probabilities when compared to both non-caring males and females. Reduction in mortality risks as a result of remaining stationary, combined with the benefits of improving egg survival, may have played an important and previously unsuspected role favoring the evolution of paternal care. Moreover, males exhibiting paternal care could also provide an honest signal of their quality as offspring defenders, and thus female preference for caring males could be responsible for maintaining the trait.

  3. Subdivision of arthropod cap-n-collar expression domains is restricted to Mandibulata

    Science.gov (United States)

    2014-01-01

    Background The monophyly of Mandibulata - the division of arthropods uniting pancrustaceans and myriapods - is consistent with several morphological characters, such as the presence of sensory appendages called antennae and the eponymous biting appendage, the mandible. Functional studies have demonstrated that the patterning of the mandible requires the activity of the Hox gene Deformed and the transcription factor cap-n-collar (cnc) in at least two holometabolous insects: the fruit fly Drosophila melanogaster and the beetle Tribolium castaneum. Expression patterns of cnc from two non-holometabolous insects and a millipede have suggested conservation of the labral and mandibular domains within Mandibulata. However, the activity of cnc is unknown in crustaceans and chelicerates, precluding understanding of a complete scenario for the evolution of patterning of this appendage within arthropods. To redress these lacunae, here we investigate the gene expression of the ortholog of cnc in Parhyale hawaiensis, a malacostracan crustacean, and two chelicerates: the harvestman Phalangium opilio, and the scorpion Centruroides sculpturatus. Results In the crustacean P. hawaiensis, the segmental expression of Ph-cnc is the same as that reported previously in hexapods and myriapods, with two distinct head domains in the labrum and the mandibular segment. In contrast, Po-cnc and Cs-cnc expression is not enriched in the labrum of either chelicerate, but instead is expressed at comparable levels in all appendages. In further contrast to mandibulate orthologs, the expression domain of Po-cnc posterior to the labrum is not confined within the expression domain of Po-Dfd. Conclusions Expression data from two chelicerate outgroup taxa suggest that the signature two-domain head expression pattern of cnc evolved at the base of Mandibulata. The observation of the archetypal labral and mandibular segment domains in a crustacean exemplar supports the synapomorphic nature of mandibulate cnc