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Chelicerata split from Mandibulata by the mid-Cambrian, as evidenced by stem-group chelicerates like Habeliida and Mollisonia present by this time. [2] The surviving marine species include the four species of xiphosurans (horseshoe crabs), and possibly the 1,300 species of pycnogonids (sea spiders), if the latter are indeed chelicerates.
The chelicerae (/ k ə ˈ l ɪ s ər iː /) are the mouthparts of the subphylum Chelicerata, an arthropod group that includes arachnids, horseshoe crabs, and sea spiders. Commonly referred to as "jaws", chelicerae may be shaped as either articulated fangs, or as a type of pincers.
Chaetopelma lymberakisi is a species of tarantula commonly known as the Cretan tarantula.Its native range is restricted to the island of Crete.It was first described in 2019 by Maria Chatzaki and Marjan Komnenov and is named in honor of Petros Lymberakis, curator of vertebrates at the Natural History Museum of Crete. [1]
However, a 2022 analysis recovered the monophyly of Merostomata, as opposed to a monophyletic Arachnida, with Xiphosura as the only modern representative in a derived position, indicating the convergence of several characteristics that supposedly united the arachnids.
Paired maxillae cut food and manipulate it during mastication. Maxillae can have hairs and "teeth" along their inner margins. At the outer margin, the galea is a cupped or scoop-like structure, which sits over the outer edge of the labium. They also have palps, which are used to sense the characteristics of potential foods.
Studies of specimens referred to this genus resolved long-standing contentiousness about the precise phylogenetic position of the Pterygotidae, providing evidence in the form of shared characteristics that Slimonia, not Herefordopterus or Hughmilleria as previously thought, was the closest sister taxon of the group.
The microscopic mite Lorryia formosa (). The mites are not a defined taxon, but is used for two distinct groups of arachnids, the Acariformes and the Parasitiformes.The phylogeny of the Acari has been relatively little studied, but molecular information from ribosomal DNA is being extensively used to understand relationships between groups.
Conclusively, the classic, morphology-based one-by-one alingment to the prosomal appendages of other chelicerates was confirm by both neuroanatomic and genetic evidences. [ 29 ] [ 30 ] Noticeably, the order of pycnogonid leg pairs are mismatched to those of other chelicerates, starting from the ovigers which are homologous to the 1st leg pair ...