On Neotropical crab spiders: description of a new species of Onocolus (Araneae: Thomisidae)

The systematics and taxonomy of Neotropical stephanopines have been extensively studied over the last years (Machado et al. 2015; Silva-Moreira Machado 2016; Machado et al. 2017, 2018; Prado et al. 2018). According to Machado et al. (2017), the genera Epicadus Simon, Epicadinus Simon and Onocolus Simon form a clade of taxa with characteristic structure of the male genitalia, consisting of a long and filiform embolus, discoid tegulum and the canoe-shaped RTA fused at the basis with an acute and curved DTA. However, the better diagnostic characters are remarkable somatic features and the structure of the female genitalia. While Epicadus present large species with three or five stout opisthosomal projections, elevated thoracic portion, sometimes presenting a median spire (Machado et al. 2018), Epicadinus is composed of smaller spiders with just three pointed opisthosomal projections and the tegument covered by elongated needle-shaped setae, which give these spiders a spiny appearance (Prado et al. 2018). The species of Onocolus, on the other hand, can be recognized by the dorsoventrally compressed prosoma, pentagonal opisthosoma, female genitalia with coiled or S-shaped copulatory ducts and predominant green body coloration. The genus Onocolus has been revised by Lise (1981). Here, we describe O. ankeri sp. nov., a species from the Amazon Forest that is remarkable by its size and color (Fig. 1).