Solifugid Relatives

[This section contributed by Paula E. Cushing]

Solifugae are in the kingdom Animalia, phylum Arthropoda, and class Arachnida. Arachnids include (depending on the researcher) 12 or 13 different orders. The order Solifugae is indisputably monophyletic (a well-supported evolutionary lineage within the class Arachnida) based on both molecular evidence (Siddharth et al. 2023) and on morphological characters found in no other arachnid including enormous two-jointed chelicerae, stalked, leaf-like chemosensory structures (malleoli or racquet organs) on the coxae and trochanters of the fourth pair of legs (Brownell & Farley 1974); prosomal stigmata; male cheliceral flagellae (Lamoral 1975); palpal coxal gland orifices; palpal suctorial organs (Cushing et al. 2005, Klann et al. 2008); opisthosomal ctenidia; a monocondylar walking leg joint between the femur and patella (Shultz 1989); and a highly developed tracheal system (Klann et al. 2005; Franz-Guess et al. 2016). These anatomical structures are illustrated and described in the Anatomy and Morphology page of this website. The order Solifugae is broadly related to other arachnid orders other members of the class Arachnida (illustrated below).

Illustrated below from upper left, clockwise, are representative arachnids in the following orders: Thelyphonida, or vinegaroons; Amblypygi, or tailless whip scorpions; Araneae, or spiders; Acarina, or mites and ticks; Opiliones, or harvestmen; and Scorpiones.

Literature Cited:

Brownell P.H. & Farley R.D. (1974): The organization of the malleolar sensory system in the solpugid, Chanbria sp. Tissue and Cell 6(3):471-485.
Cushing P.E., Brookhart J.O., Kleebe H.-J., Zito G. & Payne P. (2005): The suctorial organ of the Solifugae (Arachnida, Solifugae). Arthropod Structure & Development 34(4): 397-406.
Franz-Guess S, Kluβmann-Fricke B-J, Wirkner CS, Prendini L, Starck JM. 2016. Morphology of the tracheal system of camel spiders (Chelicerata: Solifugae) based on micro-CT and 3D-reconstruction in exemplar species from three families. Arthropod Structure & Development 45: 440-451 http://dx.doi.org/10.1016/j.asd.2016.08.004
Klann A.E., Gromov A.V., Cushing P.E., Peretti A.V. & Alberti G. (2008): The anatomy and ultrastructure of the suctorial organ of Solifugae (Arachnida). Arthropod Structure and Development 37: 3-12.
Klann, A.E., Peretti, A.V. & Alberti, G. (2005): Ultrastructure of male genital system and spermatozoa of a Mexican camel-spider of the Eremobates pallipes species group (Arachnida, Solifugae). Journal of Arachnology 33: 613-621.
Lamoral, B.H. (1975): The structure and possible function of the flagellum in four species of male solifuges of the family Solpugidae. pp. 136-141 in Proceedings of the 6th International Arachnological Congress. Vrije Universiteit of Amsterdam, Amsterdam.
Shultz, J.W. (1989): Morphology of locomotor appendages in Arachnida: evolutionary trends and phylogenetic implications. Journal of the Linnean Society of London. Zoology 97: 1—56.
Kulkarni SS, Steiner HG, Garcia EL, Iuri H, Jones RR, Ballesteros JA, Sharma PP. 2023a. Neglected no longer: Phylogenomic resolution of higher-level relationships in Solifugae. Iscience, 26(9), 107684.