The Neotropical crab spider genera Tobias Simon, 1895 and Epicadus Simon, 1895 comprise species with remarkable somatic morphology and confounding taxonomic history. The results of our recent cladistic analysis corroborate and extend preceding taxonomic assumptions in showing that Tobias is a junior synonym of Epicadus. In the present paper the six species recently transferred from Tobias to Epicadus are redescribed. Two new species are described based on both males and females: Epicadus dimidiaster sp. nov. and Epicadus tigrinus sp. nov.; the male of Epicadus granulatus Banks, 1909 is described for the first time. The diagnosis of the genus is revised, an identification key is provided, and information on geographical distribution is updated. Epicadus now comprises eleven species.

The present paper presents a cladistic analysis of the spider genus Tobias Simon, 1895. The analyses were based on a matrix with 29 terminal taxa scored for 86 morphological characters, with a dataset tested under two methodologies for character weighting (i.e. equal and implied weighting). Both analyses supported the paraphyletic relationship of Tobias with Epicadus Simon, 1895, with the former considered a junior synonym of the latter (new synonymy). Onocolus, Epicadinus and Epicadus form a clade supported by two synapomorphies, corroborating previous taxonomic assumptions regarding the proximity of these genera. Epicadus has two lineages: the ‘pustulosus clade’, comprising bark-like individuals that camouflage themselves on tree trunks and branches, and the ‘heterogaster clade’, which consists of a group of spiders that present a wide range of polychromatism and use flowers as hunting sites. Synonymies are presented and a new combination for all species previously assigned as part of Tobias is proposed. Epicadus now comprises nine species.

Here we present a revision of the Australian species of Stephanopis. The type species S. altifrons is redescribed and S. aspera, S. depressa, S. monticola, S. elongata and S. scabra are considered its junior synonyms. Males of S. altifrons, S. angulata, S. nigra, S. armata, S. fissifrons and S. longimana are described for the first time. We propose neotypes for S. nigra and S. barbipes and describe the female of the latter. Nine species are considered species inquirendae, S. thomisoides as nomen dubium and S. cheesmanae is transferred to Phrynarachne. Seven new species are described, new distribution records are provided and comments are made about the validity of the genus and its relationship with Sidymella species and other Stephanopinae genera from the Australian region.

Four Neotropical species of Sidymella Strand, 1942, S.furcillata Keyserling, 1880, S.longispina (Mello-Leitão, 1943), S.lucida (Keyserling, 1880), and S.kolpogaster (Lise, 1973) are redescribed from both sexes. The holotype of S.nigripes (Mello-Leitão, 1947) is lost and this taxon is considered a species inquierenda. Sidymellaobscura (Mello-Leitão, 1929), S.parallela (Mello-Leitão, 1929), and S.spinifera (Mello-Leitão, 1929) are all nomina dubia. Two new species are described: Sidymellaexcavatasp. nov. (males and females) and S.marmoratasp. nov. (female).

The males of Tobias caudatus Mello-Leitão, 1929 and Tobias pustulosus Simon, 1929 are described for the first time, females are redescribed and both sexes are illustrated. New distribution records are presented for both species. Tobias monstruosus Mello-Leitão, 1929 is considered a junior synonym of T. pustulosus. The types of Tobias albovittatus Caporiacco, 1954, and Tobias gradiens Mello-Leitão, 1929 are lost, and Tobias albicans Mello-Leitão, 1929 and Tobias corticatus Mello-Leitão, 1917 are known only from poorly preserved specimens, thus they all are considered nomina dubia.

We newly diagnose, illustrate, and clarify the distribution ranges of six of the most common and broadly distributed species of Tetragnatha Latreille, 1804 found in the Neotropical region. Twenty new junior synonyms from around the world are included, nine for T. bogotensis Keyserling, 1865, four for T. mandibulata Walckenaer, 1841, three for T. keyserlingi Simon, 1890, three for T. nitens (Audouin, 1826), and one for T. elongata Walckenaer, 1841. Tetragnatha vermiformis Emerton, 1884 is newly recorded from South America. The Argentine T. major Holmberg, 1876 and T. riparia Holmberg, 1876 are considered nomina dubia. Finally, we discuss the terminology of the structures of the chelicerae to establish a coherent nomenclature for teeth and fang cusps.

A matrix of 117 morphological characters scored for 77 terminal taxa was subjected to parsimony analysis under equal and implied weighting schemes and to Bayesian inference in order to test the relationships in and between Stephanopis and Sidymella species, as well as its implications for the systematics of the subfamily Stephanopinae. A sensitivity test was performed to evaluate nodal stability. Our results indicate the polyphyletism of both genera and the topologies obtained allowed the proposition of the following taxonomic acts: The "altifrons clade" is the only group considered as Stephanopis (stricto sensu), with species restricted to the Australian region; most species from the Neotropical region, hitherto attributed to this genus, formed the well-supported "pentacantha clade", while two of them, restricted to Central America, were recovered as the "championi clade". The latter shows significative evidences for the revalidation of Paratobias gen. rev.; the "cambridgei clade" emerged with I. punctata nested within, having all its component species transferred to Isala. None of the Sidymella species with Australian distribution seems to be part of this genus, which occurs in fact only in the Neotropical region and is closely related to Coenypha. This latter has an increment of three species transferred from Stephanopis. Aside from the "lucida clade", which is considered here as Sidymella (stricto sensu), three other groups and a single species emerged apart from this genus: the "hirsuta clade", "trapezia clade", "angularis clade" and Si. rubrosignata. Morphological evidences seem to justify the proposition of all these groups as new genera.

This study tests the monophyly of ant‐mimicking Thomisidae (Aphantochilinae and Strophiinae sensu Simon), redefines the composition of these taxa, proposes tribes and discusses aspects of their myrmecomorphy and biogeography. The analysis is based on a matrix composed of 113 morphological characters and 37 terminal taxa (11 Aphantochilinae, 16 Strophiinae and 10 belonging to the out‐group). The 12 most parsimonious trees with 232 steps, obtained with equally weighted characters, support the monophyly of Aphantochilinae sensu Simon. Strophiinae emerges as a paraphyletic group divided into two clades: a basal clade that groups Strophius and Strigoplus (Strophiini new status) and another clade that includes Ceraarachne, Simorcus and Ulocymus (Ceraarachnini new status) as the sister group of Aphantochilus + Bucranium (Aphantochilini new status). Diagnoses are presented for the tribes and genera in this analysis. The synonymy between Bucranium and Aphantochilus is rejected. Majellula and Acracanthostoma are considered junior synonyms of Bucranium, and Synstrophius of Ceraarachne. The monophyly of Synstrophius is not recovered, S. blanci is transferred to Ceraarachne and S. muricatus is transferred to Ulocymus. Ant‐preying behaviour appears to be basal and has been documented for Strophiini and Aphantochilini species. Myrmecomorphy, which was documented for Aphantochilus, is presumably derived. The biogeographical analysis of Aphantochilinae and Strophiinae suggests an ancient relation between Neotropical, Afrotropical and Oriental species, with probable origin after the breakup of Gondwana, that is, in early Paleogene.