The Arachnid Order Solifugae



Major Collections
Type DepositoriesPast Researchers
Present Researchers
Globel Survey/Inventory

Project Aims

Diversity Inventories

Morphology, Anatomy, Cytogenetic and Behavior Surveys

Higher Phylogeny, Classification and Biogeography

Revisionary Syntheses

Outreach Activities

Other Projects
Collecting Techniques
Preservation Techniques


Aims of the
Global Survey and Inventory of Solifugae

Morphology, Anatomy, CYTOGENETIC and Behavior Surveys

Morphology:  Investigations of external morphology, led by Cushing and Brookhart, will be undertaken across Solifugae for incorporation into phylogenetic analyses, revisions, and taxon diagnoses at all levels.  New and traditional character systems will be collated, homologized and scored in exemplars, using fresh and museum material.  Local character systems informative for particular groups (e.g., ctenidia) will be reviewed, scored and illustrated more broadly and homology statements established for divergent structures (e.g., male cheliceral flagellum) across the order.  Morphological characters to be investigated include ocelli, chelicerae (e.g., dentition, flagellar complex), pedipalps and legs (e.g., papillae, setation, tarsal segmentation, claws, empodium), coloration (propeltidium, opisthosoma), ctenidia, and setation (sclerites of metapeltidium, mesopeltidium, first dorsal opisthosomal segment).  The flagellum is arguably the most important character system in Solifugae.  Its presence, absence, and form have been widely used for family-level diagnoses and, in several families, for species delimitation (Kraepelin 1899; Lawrence 1955, 1963; Muma 1951; Roewer 1932, 1933, 1934, 1941; Wharton 1981).  Its function, however, remains speculative and it has never been homologized across the order.  Roewer (1932) provided the most detailed, illustrated comparison of flagellar morphology but further study is essential for coding character states.  Of particular interest are transitions from fixed to rotating flagella and from patches of enlarged, flexible setae to a hard, fully sclerotized flagellum.  The flagellar morphology of several groups suggests connection to an internal gland.  Exploration requires fresh material to determine the presence and distribution of glands and detailed assessment of fine structure often poorly preserved in old material.  Southern African and South American Daesiidae will illuminate transitions in gross morphology as the family is unusual in possessing divergent flagella among its genera.  Comparisons among the disjunct gylippids will similarly facilitate assessment of relationships among atypical southern African forms.

Anatomy:  The last detailed investigation of solifuge anatomy was conducted in the 19th century (Bernard 1896) and the potential contribution of anatomy to solifuge systematics is largely unknown.  Investigations on the reproductive system and spermatozoa provide novel, phylogenetically informative characters for solifuges (Alberti 1980, 2000; Alberti and Peretti 2002; Klann, Peretti and Alberti 2004, 2005; Klan, Gromov, Zeck-Capp, and Alberti 2005), while the circulatory and respiratory systems hold similar potential based on surveys of diverse arthropod taxa (Wirkner and Pass 2002; Wirkner and Richter 2003, 2004, in press).  Due to the decoupling of respiration and circulation in Solifugae (and other apulmonate arachnids), the arterial system is not as pronounced as in pulmonate arachnids with functionally linked respiration and circulation.  However, a complex three-dimensional perineural sinus exists in the prosoma (Firstman 1973), the structure and function of which, like most aspects of solifuge anatomy, has never been studied.  Investigations of the circulatory system, nervous system (particularly the corpora pedunculata or ‘brain’), respiratory system, and male and female reproductive systems (including sperm ultrastructure), led by Cushing and Brookhart, collaborating with Richter, Wirkner and Klann, will gather data for incorporation into the higher-level phylogenetic analysis. These investigations, which require fresh specimens for optimal results, will be conducted on exemplars from as many different families as can be obtained, using diverse techniques, including traditional dissection and histological sectioning, microscopy (SEM, variable-pressure SEM, TEM and confocal laser-scanning microscopy, all available at the lead institutions or their affiliates), and innovative new methods for investigating complex soft tissue anatomy, combining corrosion-casting with fast-acting resin (tested positively in solifuges), Micro-CT and 3D-reconstruction with Imaris 4.0.5 (Wirkner and Richter 2003, 2004).

Terminology, Diagnoses and Descriptions:  Senior personnel will agree to standard terminology for morphological and anatomical characters and states and a common format for descriptions, diagnoses, and other taxonomic data.  This will be well-structured, maximally informative, able to accommodate data from prior studies, and usable online, in publications and phylogenetic analysis.  Already successfully used by Prendini, DELTA, its SQL interface, DeltaAccess, and Nexus Data Editor, the sister-program for phylogenetic data matrices, is the preferred software combination.  Taxonomic descriptions in revisions will be generated automatically from data entered into DELTA.

Illustrations:  Illustrations, essential for understanding and interpreting descriptions, diagnostic and phylogenetic characters, will be produced with several techniques.  Trainees will learn traditional drawing techniques (and digitization and editing thereof using Adobe Illustrator) but digital imaging will be encouraged.  A portable Nikon SMZ645 with ocular mount for a Canon A520 digital camera, and a MicropticsTM ML1000 digital photomicrography system are available at the Denver Museum of Nature and Science and the American Museum of Natural History, respectively, for producing images in the field and at museums.  Multiple images, taken at overlapping spatial planes, can be merged with AutoMontage software, circumventing problems with reduced depth-of-field and providing completely focused images.  Images will also be produced using SEM, TEM, and confocal laser-scanning microscopy.

Interactive Identification:  Interactive keys to families, subfamilies and genera will be produced on the project website using IntKey and tools developed by the team at Discover Life.  Rather than being forced to start with a particular dichotomous character, users scroll through available characters until observing a familiar feature.  This leads to a definitive identification or a set of candidates.  As any character can have multiple states, unconforming taxa are usually eliminated after a state is chosen.  Users need not answer all state assignment queries for all characters to obtain a diagnosis, but only sort through as many characters as necessary.

Cytogenetics:  The karyotype of Solifugae is almost unknown, but expected to yield useful characters for the systematics of solifuge families based on studies of the sister-group, Pseudoscorpiones (
Šťáhlavský and Král 2004; Šťáhlavský, Henderickx and Král 2005; Šťáhlavský, Král, Harvey, and Haddad, in press).  This investigation, conducted at the Laboratory of Arachnid Cytogenetics under the direction of collaborator Král, will study the number and morphology of chromosomes in thirty exemplar species representing the families and subfamilies of Solifugae, and analyze their karyotype for constitutive heterochromatin and the positions of nucleolus organizing regions (NORs).  Chromosome preparations will be performed by plate spreading (Traut 1976), stained with 5% Giemsa in Sörensen phosphate buffer (pH 6.8) or left unstained for banding.  Suitable figures will be photographed, and 20 mitotic metaphases from each species measured and evaluated.  The distribution of constitutive heterochromatin will be performed by C-banding (Sumner 1972).  After drying, slides will be stained with 5% Giemsa in Sörensen phosphate buffer (pH 6.8). NORs will be detected by AgNO3 using the 1-step method (Howell and Black 1980) with colloidal developer.

Behavior:  Live trapping will provide opportunities for acquiring additional biological information.  We will focus on data that contribute to higher-level phylogenetic analysis.  Limited data available suggest that copulation and other aspects of solifuge reproduction are informative.  For example, the transition from indirect (Ammotrechidae, Galeodidae, Solpugidae) to direct (Eremobatidae) spermatophore transfer may be evolutionarily important, but observations are limited to nine species in four families (Punzo 1998; Muma 1966, 1966a; Cloudsley-Thompson 1961, 1967, 1967a; Wharton 1987; Junqua 1958, 1962, 1966; Peretti and Willemart, in press) 205–207. Data are lacking for eight families, and corroboration is needed for the others. Wharton (1987) described use of the flagellum during mating in Metasolpuga picta, confirming a hypothesis proposed in Lamoral’s (1975) study of the organ in four Solpugidae species, but its exact function remains unknown, despite widespread use in solifuge systematics.  Comparative data on oviposition and egg-guarding are also needed.  Available data indicate that females of some species guard eggs until hatching and immatures disperse, but others abandon eggs soon after oviposition (Wharton 1987; Muma 1966b; Wharton, unpublished data). Some species survive the oviposition/egg guarding period and produce multiple clutches, but others do not.  Egg-guarding behavior may be correlated with nymphal development, but has never been explored and general descriptions of nymphal development and dispersal (Punzo 1998) are oversimplifications.  For all these traits, phylogenetic signal is difficult to discern with so few observations.  Behavioral observations will be conducted by trainee Reddick, supervised by Wharton and Peretti.  Observations of live adults from as many different families and genera as possible will be recorded in the field using a Sony videocam.  Terraria with live specimens will be set up in the lab to supplement field observations.  Solifuges readily mate in captivity although lethargy and premature death are well-known (Punzo 1998; Wharton 1987; Muma 1966a, 1967; Esterbauer 1998; Hull-Williams 1988).  Terraria will be constructed to reduce such effects by breaking up edges, replacing soil frequently, and ensuring appropriate conditions for burrowing, and humidity for egg incubation.


Alberti, G. 1980. Zur feinstruktur des hodenpithels und der spermien von Eusimonia mirabilis Roewer 1934 (Solifugae, Arachnida). Zoologischer Anzeiger 204(5/6): 345–352.

Alberti, G. 2000. Chelicerata. Pp. 311–388. In Progress in male gamete ultrastructure and phylogeny (B.G.M. Jamieson, ed.), In Reproductive biology of invertebrates (K.G. Adiyodi & R.G. Adiyodi, eds) 9(B). Oxford and IBH: New Delhi and Calcutta.

Alberti, G. & Peretti, A.V. 2002. Fine structure of male genital system and sperm in Solifugae does not support a sister-group relationship with Pseudoscorpiones (Arachnida). Journal of Arachnology 30: 268–274.

Bernard, H.M. 1896. The comparative morphology of Galeodidae. Transactions of the Linnean Society of London, Zoology, Ser. 2, Zool. 6: 305–416, pl. 27–34.

Cloudsley-Thompson, J.L. 1961. Some aspects of the physiology and behaviour of Galeodes arabs. Experimentalis et Applicata 4(4): 257–263.

Cloudsley-Thompson, J.L. 1967. Reproduction in Solifugae. Turtox News 45: 212–215.

Cloudsey-Thompson, J.L. 1967a. Reproduction in Solifugae. Entomologist's Monthly Magazine 103: 144–145.

Esterbauer, H. 1998. Die Walzenspinne Galeodes orientalis: Beobachtungen uber Verhalten und Lebensweise. Reptilia (D) 3(6): 68–72.

Firstman, B. 1973. The relationship of the chelicerate arterial system to the evolution of the endosternite. Journal of Arachnology 1: 19–32.

Howell W.M., Black D.A. 1980. Controlled silver-staining of nucleolus organizer regions with a protective colloidal developer: a 1-step method. Experientia 36: 1014.

Hull-Williams, V. 1988. Solifugids captive management and identification. Journal of the British Tarantula Society 4(2): 7–9.

Junqua, C. 1958. Observations preliminaires sur la mue et la croissance chez les solifuges. Bulletin de la Société Zoologique de France 83: 262–264.

Junqua, C. 1962. Donnees sur la reproduction d'un solifuge: Othoes saharae Panouse. Comptes rendus hébdomadaires des séances, Paris 255: 2673–2675.

Junqua, C. 1966. Recherches biologiques et histophysiologiques sur un solifuge saharien Othoes saharae Panouse. Mémoires du Musée d'Histoire Naturelle, (NS), série A, zoologie 43: 1–124.

Klann, A.E., Peretti, A.V. & Alberti, G. 2004. Fine structural details of the male genital system and sperm cells of the Mexican camel spider Eremobates hessei (Arachnida, Solifugae). 16th International Congress of Arachnology; Gent, Belgium. [poster]

Klann, A., Peretti, A.V., & Alberti, G. 2005. Ultrastructure of male genital system and spermatozoa of a Mexican camel-spider of the Eremobates pallipes group (Arachnida:Solifugae). Journal of Arachnology 33: 613–622.

Klann, A., Gromov, A., Zeck-Kapp, G & Alberti, G. 2005. Characteristicas ultraestructurales del ovario de Galeodes caspius subfuscus Birula, 1937 y Eusimonia mirabilis Roewer 1933 (Arachnida, Solifugae).  Primer Congreso Latino americano de Aracnologia, Minas (Uruguay). [poster]o

Kraepelin, K. 1899. Zur Systematik der Solifugen. Mitteilungen aus dem Naturhistorischen Museum in Hamburg 16: 195–259, taf. I, II.

Lamoral, B.H. 1975. The structure and possible function of the flagellum in four species of male solifges of the family Solpugidae. In, Proceedings of the 6th International Arachnological Congress: 136–141. Vrije Universiteit of Amstersdam: Amsterdam.

Lawrence, R.F. 1955. Solifugae, scorpions and Pedipalpi, with checklists and keys to South African families, genera and species. Pp. 152–262. In South African Animal Life. Results of the Lund Expedition in 1950–1951. Vol. 1. Almquist and Wiksell: Stockholm.

Lawrence, R.F. 1963. The Solifugae of South West Africa. Cimbebasia 8: 1–28.

Muma, M.H. 1951. The arachnid order Solpugida in the United States. Bulletin of the American Museum of Natural History 97(2): 35–141.

Muma, M.H. 1966. The life cycle of Eremobates durangonus (Arachnida: Solpugida). The Florida Entomologist 49: 233–242.

Muma, M.H. 1966a. Mating behavior in the solpugid genus Eremobates Banks. Animal Behavior 14: 346–350.

Muma, M.H. 1966b. Egg deposition and incubation for Eremobates durangonus with notes on the eggs of other species of Eremobatidae (Arachnida: Solpugida). The Florida Entomologist 49: 23–31.

Muma, M.H. 1967. Basic behavior of North American Solpugida. The Florida Entomologist 50: 115–123.

Peretti, A.V. & Willemart, R.H. (in press). Sexual coercion does not exclude luring behavior in the climbing camel-spider Oltacola chacoensis (Arachnida, Solifugae, Ammotrechidae). Journal of Ethology []

Punzo, F. 1998. The Biology of Camel-Spiders (Aachnida, Solifugae). Kluwer Academic Publishers: Boston.

Roewer, C.F. 1932. Solifugae, Palpigradi. In Klassen und Ordnungen des Tierreichs (H.G. Bronns, ed.). 5: Arthropoda. IV: Arachnoidea. Vol. 5(IV)(4)(1): 1–160. Akademische Verlagsgesellschaft M.B.H.: Leipzig.

Roewer, C.F. 1933. Solifugae, Palpigradi. In Klassen und Ordnungen des Tierreichs (H.G. Bronns, ed.). 5: Arthropoda. IV: Arachnoidea. Vol. 5(IV)(4)(2–3): 161–480. Akademische Verlagsgesellschaft M.B.H.: Leipzig.

Roewer, C.F. 1934. Solifugae, Palpigradi. In Klassen und Ordnungen des Tierreichs (H.G. Bronns, ed.). 5: Arthropoda. IV: Arachnoidea. Vol. 5(IV)(4)(4–5): 481–723. Akademische Verlagsgesellschaft M.B.H.: Leipzig.

Roewer, C.F. 1941. Solifugen 1934–1940. Veröffentlichungen des Deutschen Kolonial Ubersee-Museums, Bremen 3: 97–192.

Šťáhlavský F. & Král J. 2004. Karyotype analysis and achiasmatic meiosis in pseudoscorpions of the family Chthoniidae (Arachnida: Pseudoscorpiones). Hereditas 140: 49–60.

Šťáhlavský F., Henderickx H. & Král J. 2005. Karyotype study on pseudoscorpions of the genus Lasiochernes Beier (Pseudoscorpiones: Chernetidae). Folia Biologica (Kraków) 53: 69–74.

Šťáhlavský F., Král J., Harvey M.S. & Haddad C.R. (in press). A karyotype study on the pseudoscorpion families Geogarypidae, Garypinidae and Olpiidae (Arachnida: Pseudoscorpiones). European Journal of Entomology.

Sumner A.T. 1972. A simple technique for demonstrating centromeric heterochromatin. Experimental Cell Research 75: 304–306.

Traut W. 1976. Pachytene mapping in the female silkworm Bombyx mori L. (Lepidoptera). Chromosoma 58: 275–284.

 Wharton, R.A. 1981. Namibian Solifugae (Arachnida). Cimbebasia Memoir 5: 1–87.

Wharton, R.A. 1987. Biology of the diurnal Metasolpuga picta (Kraepelin) (Solifugae, Solpugidae) compared with that of nocturnal species. Journal of Arachnology 14(3): 363–383.

Wirkner, C.S. & Pass, G. 2002. The circulatory system in Chilopoda: Evolutionary and phylogenetic aspects. Acta Zoologica 83: 197–202.

Wirkner, C.S. & Richter, S. 2003. The circulatory system of the Phreatoicidea: implications for the isopod ground pattern and peracarid phylogeny. Arthropod Structure and Development 32: 337–347.

Wirkner, C.S. & Richter, S. 2004. Improvement of micro anatomical research by combination of corrosion casts with micro CT and 3D reconstruction exemplified on the circulatory organs of the woodlouse. Microscopy Research and Technique 64: 250–254.

Wirkner, C.S. & Richter. S. (in press). The circulatory system and its spatial relations to other major organ systems in Spelaeogriphacea and Mictacea (Malacostraca, Crustacea) – a three-dimensional analysis. Zoological Journal of the Linnean Society.

Wirkner, C.S. & Richter. S. (in press). The circulatory system in Mysidacea – implications for the phylogenetic position of Lophogastrida and Mysida (Malacostraca, Crustacea). Journal of Morphology.


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