30 September, 2009

New Scorpion Files species biography: Tityus obscurus

Michiel Cozijn has written another informative species biography for The Scorpion Files. This time he has looked at the South American Tityus obscurus (Gervais, 1843) in the Buthidae family.

Species biography for Tityus obscurus

A big thanks to Michiel for supporting The Scorpion Files!

Species biographies previously written by Michiel Cozijn:

Babycurus gigas
Babycurus jacksoni
Grosphus madagascariensis
Rhopalurus laticauda

25 September, 2009

The evolution of troglobitism and more on typhlochactid phylogeny

Recently, there have been several papers published on the troglomorphic scorpions of North America (see recent blog postings). Prendini, Francke & Vignoli have now published an article that focus on the evolution of troglobitic and troglomorphic scorpions and discuss if troglobitism can be considered an evolutionary dead-end. The paper also take a look at typhlochactid trichobothriotaxy and phylogeny.

A summary of the paper can be found below, but it is interesting to note that the authors conclude that troglobitism is not an evolutionary dead-end: that an ancestral troglobitic condition can evolve into a troglomorphic, endogean (above surface) condition. The authors belive that this is the case for the troglomorphic, litter dwelling species of Typhlochactas. In plain text: Specialized, troglobitic cave dwelling scorpions can go back to the surface and during evolution evolve into new species adapted to a more variable and demanding environment. So troglobitism is not necessarly an evolutionary dead-end.

The scorpion family Typhlochactidae Mitchell, 1971 is endemic to eastern Mexico and exclusively troglomorphic. Six of the nine species in the family are hypogean (troglobitic), morphologically specialized for life in the cave environment, whereas three are endogean (humicolous) and comparably less specialized. The family therefore provides a model for testing the hypotheses that ecological specialists (stenotopes) evolve from generalist ancestors (eurytopes) and that specialization (in this case to the cavernicolous habitat) is an irreversible, evolutionary dead-end that ultimately leads to extinction. Due to their cryptic ecology, inaccessible habitat, and apparently low population density, Typhlochactidae are very poorly known. The monophyly of these troglomorphic scorpions has never been rigorously tested, nor has their phylogeny been investigated in a quantitative analysis. We test and confirm their monophyly with a cladistic analysis of 195 morphological characters (142 phylogenetically informative), the first for a group of scorpions in which primary homology of pedipalp trichobothria was determined strictly according to topographical identity (the ‘‘placeholder approach’’). The phylogeny of Typhlochactidae challenges the conventional wisdom that ecological specialization (stenotopy) is unidirectional and irreversible, falsifying Cope's Law of the unspecialized and Dollo's Law of evolutionary irreversibility. Troglobitism is not an evolutionary dead-end: endogean scorpions evolved from hypogean ancestors on more than one occasion.

Prendini L, Francke OF, Vignoli V. Troglomorphism, trichobothriotaxy and typhlochactid phylogeny (Scorpiones, Chactoidea): more evidence that troglobitism is not an evolutionary dead-end. Cladistics. 2010;26(2):117-142. [Subscription required for full text]

Thanks to Oscar Francke for sending me this paper!

Family Typhlochactidae

20 September, 2009

Major revision of troglomorphic North American scorpions results in a new family and genus

The fantastic troglomorphic and trglobitic scorpions of Mexico have been placed in different families since their discovery. The study of these enigmatic scorpions has been difficult because of their cryptic ecology (some species living deep in narrow caves) and low population numbers. Only 29 specimens have been collected in the last 40 years. The species has until recently been placed in the family Superstitioniidae.

In a recent revision of all known specimens, Valerio Vignoli & Lorenzo Prendini (2009) have redescribed all species and conducted a cladistic analysis. This has resulted in the elevation of the old family Typhlochactidae Mitchell, 1971. In addition, the new genus Stygochactas Vignoli & Prendini, 2009 has been created to accomodate the species S. granulosus (Sissom & Cokendolpher, 1998), previously placed in Typhlochactas Mitchell, 1971.

The following taxa have been transfered from Superstitioniidae to Typhlochactidae:

Alacran tartarus Francke, 1982
Alacran chamuco Francke, 2009 (not in this paper, but published a few weeks ago)
Sotanochactas elliotti (Mitchell, 1971)
Stygochactas granulosus (Sissom & Cokendolpher, 1998)
Typhlochactas cavicola Francke, 1986
Typhlochactas mitchelli Sissom, 1988
Typhlochactas reddelli Mitchell, 1968
Typhlochactas rhodesi Mitchell, 1968
Typhlochactas sissomi Francke et al., 2009
Typhlochactas sylvestris Mitchell & Peck, 1977

The scorpion family Typhlochactidae Mitchell, 1971, endemic to eastern Mexico, comprises nine troglomorphic species specialized for life in hypogean and endogean habitats. Due to their cryptic ecology, inaccessible habitat, and apparently low population density, Typhlochactidae are poorly known. Only 29 specimens have been collected in 40 years. Four species are known from a single specimen, two species are known only from the male and three only from the female. We provide an illustrated revision of the family based on a reexamination of most specimens in the world’s collections, including new specimens collected after the original descriptions and older specimens not previously described. Based on results of a recent cladistic analysis, Typhlochactidae are elevated, for the first time, from their former rank as subfamily, first of Chactidae and, more recently, of Superstitioniidae. Alacraninae, new subfamily is created to accommodate Alacran Francke, 1982. Stygochactas, new genus, is created to accommodate Typhlochactas granulosus Sissom and Cokendolpher, 1998 in a new combination. Sotanochactas Francke, 1986, Stygochactas and Typhlochactas Mitchell, 1971 are retained in subfamily Typhlochactinae Mitchell, 1971. Diagnoses of the family and subfamilies are presented, followed by a key to the genera and species, revised diagnoses of the genera, revised diagnoses and descriptions, tabulated meristic data, and distribution maps of the species. Descriptions and diagnoses are illustrated with ultraviolet fluorescence and visible light photographs, providing a visual atlas to the morphology of these remarkable scorpions. A review of their taxonomic history is provided, the importance of trichobothriotaxy for their systematics discussed, and several misconceptions in the literature clarified.

Vignoli V, Prendini L. Systematic revision of the troglomorphic North American scorpion family Typhlochactidae (Scorpiones, Chactoidea). Bulletin of the American Museum of Natural History. 2009; (326):1-94. [Free fulltext]

Family Typhlochactidae

11 September, 2009

Biodiversity of Venezuela: Four new species of Tityus

I've learned about another new paper from the late Manuel Gonzalez Sponga. Here four new species of Tityus Koch, 1836 (Buthidae) are described from the Venezuelan states of Monagas, Sucre and Bolivar:

Tityus longidigitus Gonzalez Sponga, 2008
Tityus quiriquirensis Gonzalez Sponga, 2008
Tityus romeroi Gonzalez Sponga, 2008
Tityus sanfernandoi Gonzalez Sponga, 2008

Four new species of Venezuelan scorpions of the genus Tityus Koch. 1836 (Buthidae): Tityus longidigitus, Tityus quiriquirensis, Tityus romeroi and Tityus sanfernandoi are described. They live in the oriental and Imataca mountain range regions in Venezuela. in altitudes between 100 and 200 m. Drawing of significant morphological characters are presented to diagnose the species: tables with morphometric characters are given. Typical localitions are indicated in the map.

Gonzalez Sponga MA. Biodiversidad en Venezuela. Descripcion de cuatro nuevas especies del genero Tityus Koch, 1836 (Scorpionida: Buthidae) de los estados Monagas, Sucre y Bolivar. Bol Acad C Fis Mat y Nat. 2008;68 (4):9-30.

Family Buthidae

The genus Orobothriurus in central Argentina and a descrption of a new species

Orobothriurus Maury, 1975 (Bothriuridae) is an interesting genus where most species occur at high altitudes above 2500 m in South America. Most high altitude species are found in the Andes mountain range, but species have also been found in other locations.

Andres Ojanguren Affilastro and co-workers have now published a study on Orobothriurus in Argentina with a description of a new species:

Orobothriurus grismadoi Ojanguren Affilastro, Campon, Silnik & Mattoni, 2009 (Bothriuridae)

In the same paper, Orobothriurus bivittatus (Thorell, 1877) is synonymised with O. alticola (Pocock, 1899).

New data on the scorpion genus Orobothriurus Maury 1976 in central Argentina are provided. Orobothriurus grismadoi n.sp. is described; this species occurs in high altitudes in El Nevado mountain chain, an isolated orographic system in Southern Mendoza, Argentina, separated by almost 200 km from the Andes Mountain chain. This species is closely related to Orobothriurus alticola (Pocock, 1899). This is the southernmost record for the genus about 300 km south from previous records. Orobothriurus bivittatus (Thorell, 1877) is synonymised with O. alticola based on material recently collected in El Tontal mountain chain. We also provide new data about the distribution and intraspecific variability of O. alticola.

Ojanguren-Affilastro AA, Campon FF, Silnik SL, Mattoni CI. The genus Orobothriurus Maury in central Argentina with description of a new species from El Nevado mountain chain in Mendoza Province (Scorpiones: Bothriuridae). Zootaxa. 2009; (2209):28-42. [Subscription required for fulltext]

Family Bothriuridae

08 September, 2009

"Scorpion Strongmen" - Who's got the strongest grip?

The size of scorpion claws (pincers) vary a lot. Some species has long and slender pedipalps (like Leiurus), while others have broad and powerful claws (like Pandinus). But who's got the strongest pincer force?

A. van der Meijden and co-workers have published a comparison of claw size and pincer force in seven species. Scorpions with the highest claws had the strongest grip. The authors suggest that slender claws may be an adaption to speed (catching quick and elusive prey) rather than maximum force. Large claws may be an adaption to defense against predators, but can also have other functions (like burrowing).

A key feature of the ancient body plan of scorpions is the pincer or chela. These multifunctional structures vary considerably in size and shape between different scorpion species. Here we provide the first comparative data on the pinching performance of the chelae of seven species of scorpions exemplifying the extremes of the shape range from slender to robust; Leiurus quinquestriatus, Androctonus amoreuxi, Androctonus australis, Hadogenes sp., Pandinus imperator, Scorpio maurus and Pandinus cavimanus (in the order of decreasing chela height to width ratio). Size-corrected chela height correlates highly with maximum pinch force. Independent contrasts suggest that the correlation of chela width, height and fixed finger length with maximum pinch force is independent of phylogeny, suggesting an adaptive component to the evolution of chela shape and performance.

van der Meijden A, Herrel A, Summers A. Comparison of chela size and pincer force in scorpions; getting a frist grip. J Zool. 2009:1-7. DOI:10.1111/j.1469-7998.2009.00628.x [This is an early view article - Subscription required for fulltext]

Thanks to Dr. van der Meijden for sending me the paper!

07 September, 2009

A new cave scorpion from Mexico

Mexico has many deep cave system and in these system there are some fantastic troglobitic scorpions (lacking eyes and pigmentation). Oscar Francke has now described a new species in the genus Aalcran from a cave in Oaxaca, Mexico. This is the seccond species in this genus. The other species (A. tartarus Francke, 1982) is only known from a handful of specimens.

Alacran is currently placed in the family Superstitionidae, but according to the information in Francke's paper a forthcomming paper by Vignoli & Prendini will reinstate the family Typhlochactidae Mitchell, 1971 for Alcran and probably other similar genera in the family Superstitionidae. I will blog details about this as soon as I have access to the paper and it's formally published.

Alacran chamuco Francke, 2009 (Superstitionidae/Typhlochactidae)

Alacran chamuco sp. nov., a new eyeless, troglobitic scorpion from Te Cimutaa, Valle Nacional, is described. This is the second known species in the genus; sharing with Alacran tartarus a very similar trichobothrial pattern and the lack of “petite” trichobothria—both unique characters in the family Typhlochactidae. The new species differs from A. tartarus in the pedipalp finger dentition and the relative size of the telson. The two cave systems in Oaxaca where the two species of Alacran occur are approximately 75 kilometers apart.

Francke OF. A new species of Alacran (Scorpiones: Typhlochactidae) from a cave in Oaxaca, Mexico. Zootaxa. 2009; (2222):46-56. [Subscription required for fulltext]

Thanks to Dr. Jean-Michel Pacaud for sending me the Francke paper!

Family Superstitionidae

04 September, 2009

Social behavior and shelter selection in Mesobuthus gibbosus

Dimitris Kaltsas, Iasmi Stathi & Moysis Mylonas have published a study of intraspecific differentiation of social behavior and shelter selection in the buthid Mesobuthus gibbosus (Brulle, 1832) in two locations in Greece.

Their results indicate that seasonal shelter selection and social behavior of M. gibbosus are regulated by climatic factors and differ in relation to intraspecific (within the species) competition. Sociality in the form of sharing shelters will cease in the warm period because of higher activity in prey capture and hence an increased intraspecific competition (but no connection to an increased danger of cannibalism as M. gibbosus seems to be a non-cannibalistic species).

We compared seasonal shelter selection and social behavior of Mesobuthus gibbosus from autumn to mid-summer in two similar phryganic ecosystems, in continental Greece (near Volos city) and in insular Greece (eastern Crete), and in the laboratory under simulated abiotic conditions. Our results showed that shelter selection is a critical indicator of the seasonal social behavior of the species. The abrupt climatic changes in spring caused a differentiation in shelter selection between the cold period (November–February) and the warm period (March–June) at both sites. Sociality was exhibited only during winter in the field and was more extensive under cold conditions in the laboratory. Co-occurrence of scorpions proved to be age-specific, facilitated by population density and by harsh abiotic conditions during winter, and negatively influenced by intraspecific competition, which was higher in continental Greece. The response of scorpions to changes of abiotic factors reveals synchronization of seasonal shelter selection with climatic changes.

Kaltsas D, Stathi I, Mylonas M. Intraspecific differentiation of social behavior and shelter selection in Mesobuthus gibbosus (Brull,, 1832) (Scorpiones: Buthidae). Journal of Ethology. 2009 Sep;27 (3):467-73. [Subscritpion required for fulltext]

Photo: Mesobuthus gibbosus from northwestern Crete, Greece (Photo: Jan ove Rein).

Family Buthidae

02 September, 2009

Redescription of Tityopsis aliciae

The genus Tityopsis Armas, 1974 has only three known species (two in Cuba and one in Mexico). Tityopsis aliciae Armas & Martin-Frias, 1998 has only been known from one poorly preserved specimen. Vianey Vidal-Acosta and Oscar Francke have now published a redescription of the species based on a new specimen.

Tityopsis aliciae Armas y Martín-Frías, 1998 is redescribed based on an adult female from the type locality, Tehuantepec, Oaxaca. The holotype, previously the only known specimen, is a subadult female and it is poorly preserved, which led to some inaccuracies in the original description. There were some doubts regarding the type locality, but the finding of an adult female confirms the presence of this genus, the second belonging to the family Buthidae, in Mexico.

Vidal-Acosta V, Francke OF. Redescripcion de Tityus aliciae (Scorpiones: Buthidae). Revista Mexicana de Biodiversidad. 2009;80:333-9.

Thanks to Oscar Francke for sending me this paper!

Family Buthidae

01 September, 2009

A new Centruroides from Mexico

Carlos Santibanez-Lopez and Javier Ponce-Saavedra have recently described a new Centruroides species from Mexico:

Centruroides serrano Santibanez-Lopez & Ponce-Saavedra, 2009 (Buthidae)

Centruroides serrano sp. nov. from the Sierra Juárez of Oaxaca (Villa Alta District) is described. This is the eleventh species of the genus reported from Oaxaca and the first one reported from this area. It occurs from 500 m to 1 500 m. It is compared to C. baergi Hoffmann, 1932, C. nigrovariatus Pocock, 1898 and C. hoffmanni Armas, 1996 due to its overall similarity. To separate these 4 species, a principal component analysis was conducted. A list of the species of this genus from Oaxaca is provided.

Santibanez-Lopez CE, Ponce-Saavedra J. A new species of Centruroides (Scorpiones: Buthidae) from the northern mountain range of Oaxaca, Mexico. Revista Mexicana de Biodiversidad. 2009;80:321-31.

Thanks to Carlos Eduardo Santibáñez López for sending me the paper!

Family Buthidae