Osvaldo Villarreal

Dr. Osvaldo Villarreal

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Research Focus & Metrics

Academic Career Length

21Years (2006-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 October 2020 in European Journal of Taxonomy
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BHBernhard A. Huber
Bernhard A. Huber
OVOsvaldo Villarreal
Osvaldo Villarreal
We present a comprehensive revision of the pholcid spider collection of M.A. González-Sponga, who between 1998 and 2011 described 22 new genera and 51 new species of Pholcidae from Venezuela. In addition, we treat the pholcid material collected during three expeditions to Venezuela conducted between 2002 and 2020. Of González-Sponga’s pholcid taxa we recognize three genera and 24 species as valid. We describe 43 new species (all from males and females) in one new and 13 previously described genera; four genera are newly recorded for Venezuela. We describe the previously unknown females of 15 species, present new records for 46 previously described species, synonymize one genus and one species, and correct numerous minor errors in previous publications on Venezuelan pholcids. At the generic level, the Venezuelan pholcid fauna now appears fairly well known, but available data on distribution and endemism suggest that many species remain undiscovered and undescribed. Despite the obvious gaps, our data are congruent with previous studies on other taxa that have the highest levels of endemism in the Venezuelan Andes, the Coastal Ranges, and the Guyana Highlands. The Falcón Region in particular shows a complex mosaic of biogeographic relationships with other regions. We provide new biological data on numerous species. We document the first cases of evolutionary microhabitat shifts in the genera Mecolaesthus Simon, 1893 and Priscula Simon, 1893. We document several cases of close congeners sharing localities, usually in slightly to conspicuously different microhabitats, sometimes apparently in identical microhabitats. We document several cases of color polymorphism, mostly intersexual, in Metagonia conica (Simon, 1893) both intersexual and among males. We document further cases of two rare phenomena in Pholcidae: use of specific non-silken structures for retreats (in Pisaboa Huber, 2000) and egg parasitism (in Priscula).

1 August 2007 in The Journal of Arachnology
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AKAdriano B Kury
Adriano B Kury
OVOsvaldo Villarreal
Osvaldo Villarreal
CSCristiano Sampaio
Cristiano Sampaio

10 February 2016 in PLOS ONE
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OVOsvaldo Villarreal
Osvaldo Villarreal
Gustavo Silva de MirandaGustavo Silva de Miranda
Gustavo Silva de Miranda
AGAlessandro Ponce de Leão Giupponi
Alessandro Ponce de Leão Giupponi
The homology of three somatic systems in Schizomida is studied yielding the following results: (1) proposal of homology and chaetotaxy of abdominal setae in Surazomus; (2) revision of the cheliceral chaetotaxy in Schizomida, with suggestion of new homology scheme between Hubbardiidae and Protoschizomidae, description of a new group of setae in Hubbardiinae (G7), and division of setae group 5 in two subgroups, G5A and G5B; (3) proposal of segmental homology between trimerous and tetramerous female flagellum in Hubbardiinae with association of segment III of tri-segmented species to segments III + IV of tetra-segmented species. Considerations about the dorsal microsetae on the male flagellum are made. The genus Surazomus in Ecuador is revised. The sympatric species Surazomus palenque sp. nov. and S. kitu sp. nov. (Ecuador, Pichincha) are described and illustrated. The female of S. cuenca (Rowland and Reddell, 1979) is described, with two new distributional records for the species. Surazomus cumbalensis (Kraus, 1957) is recorded for the first time from Ecuador (Pichincha).

26 April 2019 in Journal of Natural History
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OVOsvaldo Villarreal
Osvaldo Villarreal
LÁLudson Neves de Ázara
Ludson Neves de Ázara
AKAdriano B Kury
Adriano B Kury
The penial and tarsal morphology of Protimesius is studied and morphological data support the revalidation of Obidosus with the subsequent new combinations (20 species) and restored combinations (two species). Emended diagnoses are proposed for both genera, and two cave-dwelling new species of Protimesius are described and illustrated: P. lucifer sp. nov. (Pará state) and P. orcus sp. nov. (Ceará state). An identification key to the species of Protimesius and distributional maps of Obidosus and Protimesius are provided. http://www.zoobank.org/urn:lsid:zoobank.org:pub:C4E9C04D-A646-41E4-AE59-B6D0C951DEAB


7 June 2015 in Zoological Studies
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OVOsvaldo Villarreal
Osvaldo Villarreal
AKAdriano B Kury
Adriano B Kury
RPRicardo Pinto-Da-Rocha
Ricardo Pinto-Da-Rocha
Background: The distinction of genera in Cranaidae (as in many other Gonyleptoidea) is traditionally made on the basis of a combination of armature of scutal areas, tarsomere counts, and some secondary sexual structures (which may vary among males). This historically led to the creation of non-natural groups of species as meaningless genera. Here some nominal genera of Cranaidae are addressed, and this paucity of diagnostic characters is alleviated with more detailed diagnoses and descriptions.Results: The poorly known genusVentrifurcaRoewer, 1913, hitherto monotypic, is revisited. The generaMicrocranausRoewer, 1913 (with three species),CayabeusRoewer, 1932 (monotypic), andAngistrius(monotypic) are here proposed as junior subjective synonyms ofVentrifurca. Both type species ofMicrocranausandCayabeusare considered junior subjective synonyms ofVentrifurca albipustulata; thus,Cayabeus perlatusRoewer, 1932 andMicrocranaus pustulatusRoewer, 1913 = Ventrifurca albipustulataRoewer, 1913.Ventrifurca abnormiscomb. nov. is proposed forAngistrius abnormisRoewer, 1932.Rhopalocranaus dybasiGoodnight & Goodnight, 1947, currentlyNeocranaus dybasi, is transferred toVentrifurca, and the new combinationVentrifurca dybasicomb. nov. is herein proposed for it.Ventrifurca albipustulatais redescribed, and for the first time, the male genitalia is described and illustrated, and SEM pictures are offered. The new speciesVentrifurca caffeinicasp. nov. is described from Quindío department, Colombia. A new diagnosis toVentrifurcais proposed. The relationships ofVentrifurcaare discussed. The remaining two species ofMicrocranausare transferred to the family Manaosbiidae: (1)Microcranaus columbianusnewly combined asRhopalocranaus columbianus(Roewer, 1963) and (2)Microcranaus gracilisnewly combined asCamelianus gracilis(Roewer, 1913). New diagnoses are given for both species.Conclusions: A non-monotypic genus of Andean Cranaidae is defined, associated with a well-defined geographic region, and unloaded of extraneous species which belong to another family. Recognition of variation in heteromorphic males reveals past errors of assignment when only limited samples were available for study.