Evidence of Xysticus ulmi (Hahn) (Araneae: Thomisidae) Predation on Adult Cassida viridis Linnaeus (Coleoptera: Chrysomelidae)

Posted by
  Evidence of Xysticus ulmi (Hahn) (Araneae: Thomisidae) Predation on Adult Cassida viridis Linnaeus (Coleoptera: Chrysomelidae) Tortoise beetles (Chrysomelidae: Cassidinae) have several morphological and behavioral antipredator traits. For example, the soft larvae accumulate their feces and exuviae from previous instars to create a so-called “fecal shield” (Engel 1936; Kosior 1975), which functions as a defense against many predator guilds (Eisner and Eisner 2000; Eisner et al. 1968; Vencl et al. 1999, 2005; Vencl and Srygley 2013). Adults are characterized by their explanate and well-sclerotized pronota and elytra, which cover all soft parts of the body, thereby forming a tortoise-shaped shield (Buzzi 1988; Engel 1936; Jolivet 1997; Jolivet and Verma 2002; Selman 1988; Windsor et al. 1992) (Fig. 1A). Furthermore, the adults are known for their ability to grip firmly to surfaces with both tarsal claws and pads, which renders them difficult to capture (Buzzi 1988; Engel 1936; Joliv...

Out of North Africa: Evolution and biogeography of Afro-Arabian dwarf tarantulas (Theraphosidae, Ischnocolinae)

Posted by

 

Out of North Africa: Evolution and biogeography of Afro-Arabian dwarf tarantulas (Theraphosidae, Ischnocolinae)

Abstract

Large-scale vicariant events are expected to create congruent phylogeographic patterns among unrelated taxa. A continental-wide disjunction displayed by unrelated plant taxa across Afro-Arabia (the RAND flora pattern) has been traditionally explained as a consequence of late Miocene aridification of the region and the formation of the Sahara Desert. We implement genomic data (UCE), divergence time estimation and biogeographic analyses to uncover the origins of RAND pattern distribution in dwarf tarantula genus Ischnocolus Ausserer, 1871. The results suggest that the disjunct distribution of Ischnocolus resulted from ecological vicariance driven by the Middle Miocene climate cooling, predating the timing of the aridification of the region. Our results thus bring evidence of phylogeographic discordance of the RAND pattern origins among different taxa. Conserved lifestyle and the preference for humid environments among the early diverging Ischnocolus lineages also suggest that dispersal across Afro-Arabia was likely catalyzed by interspecific competitive exclusion. Subsequent lifestyle switches, that enabled the dwarf tarantulas to successfully colonize dry environments, evolved repeatedly in the group’s evolution. Additionally, we delimit the boundaries of the genus Ischnocolus and assess its position within the tarantula phylogeny. As a consequence, we revalidate the genus Luphocemus Denis, 1960, which is endemic to North Africa.
Korba, J., & Opatova, V. (2026). Out of North Africa: Evolution and biogeography of Afro-Arabian dwarf tarantulas (Theraphosidae, Ischnocolinae). Molecular Phylogenetics and Evolution, 108559. https://doi.org/10.1016/j.ympev.2026.108559