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Taxonomy and systematics of the Australasian gum nut orb-weaving spider genus Carepalxis (Araneae, Araneidae)

Pedro Castanheira , Dimitar Dimitrov , Renner Luiz Cerqueira Baptista, Nikolaj Scharff, Volker Framenau

Abstract

We revised the orb-weaving spider genus Carepalxis L. Koch, 1872 and tested its monophyly using Maximum Likelihood and Bayesian Inference phylogenetic analyses, comparing our results to a previously published family-level dataset on world-wide Araneidae. We studied the placement of the genus and the classification of the informally termed clade ‘backobourkiines’ using phylogenetic analyses based on two mitochondrial genes, cytochrome c oxidase subunit 1 (COI) and 16S rRNA, and two nuclear genes, 28S rRNA and 18S rRNA. Around 12,000 araneid records (vials) from major Australian and overseas collections were examined during our taxonomic revision. All phylogenetic analyses supported a monophyletic ‘backobourkiines’ clade, but found a polyphyletic Carepalxis, with its Australasian representatives being part of the ‘backobourkiines’ and the Neotropical species being related to the Neotropical Ocrepeira Marx, 1883. Consequently, the genus was revised to include seven endemic Australian species, Carepalxis montifera L. Koch, 1872 (type species), C. bilobata Keyserling, 1886, C. ferreirasousai sp. nov., C. kolla sp. nov., C. megalostylus sp. nov., C. tholos sp. nov., and C. tuberculata Keyserling, 1886 (= C. furcifera (Keyserling, 1886) syn. nov.), in addition to C. beelzebub (van Hasselt, 1873) (= C. suberosa (Thorell, 1881) syn. nov. = C. tuberculifera (Thorell, 1881) comb. nov. & syn. nov. = C. tricuspidata Chrysanthus, 1961 syn. nov.) which is present in Australia, Indonesia (West Papua) and Papua New Guinea. The following new combinations for Neotropical species previously placed in Carepalxis were proposed: Ocrepeira camelus (Simon, 1895) comb. nov., Ocrepeira gibbosa (O. Pickard-Cambridge, 1889) comb. nov., Ocrepeira perpera (Petrunkevitch, 1911) comb. nov., Ocrepeira quasimodo (Ferreira-Sousa & Motta, 2022) comb. nov., and Ocrepeira topazio (Ferreira-Sousa & Motta, 2022) comb. nov. Within the backobourkiines, Carepalxis can be recognised by the presence of two cephalic humps in females and two enlarged megaspines apically on tibia II of males (both here considered synapomorphies of the genus), anteriorly elevated abdomen usually with numerous tubercles, humps or sigilla in addition to the humeral humps, an elongated male pedipalp median apophysis bearing a small projection, and a female epigyne with broad lateral lobes, and, whenever present, conspicuous transverse slits instead of baso-lateral flaps.

IS25009  Accepted 24 June 2025

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