The cockroach genus Arenivaga is revised. Forty-eight Arenivaga species are recognized with nine previously known species and 39 described as new including the following: A. pagana sp. n., A. grandiscanyonensis sp. n., A. haringtoni sp. n., A. hopkinsorum sp. n., A. umbratilis sp. n., A. tenax sp. n., A. impensa sp. n., A. trypheros sp. n., A. darwini sp. n., A. nalepae sp. n., A. sequoia sp. n., A. mckittrickae sp. n., A. gaiophanes sp. n., A. belli sp. n., A. estelleae sp. n., A. delicata sp. n., A. mortisvallisensis sp. n., A. milleri sp. n., A. pratchetti sp. n., A. gumperzae sp. n., A. rothi sp. n., A. ricei sp. n., A. adamsi sp. n., A. nicklei sp. n., A. akanthikos sp. n., A. moctezuma sp. n., A. paradoxa sp. n., A. apaeninsula sp. n., A. hebardi sp. n., A. dnopheros sp. n., A. aquila sp. n., A. florilega sp. n., A. galeana sp. n., A. gurneyi sp. n., A. pumila sp. n., A. hypogaios sp. n., A. diaphana sp. n., A. nocturna sp. n., A. alichenas sp. n. All species are described or redescribed, major morphological features are illustrated, distributions are characterized, and the biology of the species is reviewed. A neotype series is designated for A. investigata Friauf & Edney.

Arenivaga occur across the American Southwest and Mexico, as well as in the scrub and high pine communities of Florida. This study analyzes the relative contribution of 22 abiotic and one biotic variable to the niche of the genus Arenivaga. This analysis revealed that more than 95% of their ecological niche is described by eight variables: soil, isothermality, minimum temperature of the coldest month, mean temperature of the driest quarter, annual precipitation, precipitation of the driest month, precipitation of the wettest quarter and ground cover. These eight variables with respect to their relative contributions to the niche of the genus as a whole as well as the individual niches of 27 species in the genus were then examined. This revealed the similarity of niche composition of most of the species, as well as how varied the niches were of several species. A species dendrogram built from similarity of contribution of the eight variables to niche composition was compared to a phylogeny of the genus, but few similarities in topology were found. This analysis revealed that soil is the most important contributor to these species' niches, followed by precipitation of the driest month, and finally, precipitation of the wettest quarter. It also confirmed that the majority of Arenivaga species have niches comprised of similar, but not identical, proportions of as few as four, and as many as eight ecological variables. Currently there is no evidence to support niche conservatism between closely related species, indicating that adapting to new and variable niches is one of the drivers of speciation in this genus.

Florida scrub is a xeric ecosystem associated with the peninsula's sand ridges, whose intermittent Pliocene–Pleistocene isolation is considered key to scrub endemism. One scrub origin hypothesis posits endemics were sourced by the Pliocene dispersal of arid‐adapted taxa from southwestern North America; a second invokes Pleistocene migration within eastern North America. Only one study to date has explicitly tested these competing hypotheses, supporting an eastern origin for certain scrub angiosperms. For further perspective, we conducted a genetic analysis of an endemic arthropod, the Florida sand cockroach (Arenivaga floridensis), with two aims: (1) to reconstruct the peninsular colonization and residence history of A. floridensis and (2) determine whether its biogeographic profile favors either origin hypothesis. We sequenced the cox2 mitochondrial gene for 237 specimens (65 populations) as well as additional loci (cox1, nuclear H3) for a subset of Florida roaches and congeners. Using Network and Bayesian inference methods, we identified three major lineages whose genetic differentiation and phylogeographical structure correspond with late Pliocene peninsula insularization, indicating Arenivaga was present and broadly distributed in Florida at that time. Stem and crown divergence estimates (6.36 Ma; 2.78 Ma) between A. floridensis and western sister taxa span a period of extensive dispersal by western biota along an arid Gulf Coast corridor. These phylogeographical and phylogenetic results yield a biogeographic profile consistent with the western origin hypothesis. Moreover, age estimates for the roach's peninsular residence complement those of several other endemics, favoring a Pliocene (or earlier) inception of the scrub ecosystem. We argue that eastern versus western hypotheses are not mutually exclusive; rather, a composite history of colonization involving disparate biotas better explains the diverse endemism of Florida scrub.

Heteranassa Smith (Erebidae, Omopterini), native to the southwestern United States and Mexico, includes two recognized species, namely Heteranassa mima (Harvey) and Heteranassa fraterna Smith. These are separated mainly by subtle differences in wing color and pattern, leading to speculation about the validity of the described species. This study examines variation in external and internal morphology across the geographic range of the genus, aiming to clarify species limits, describe morphology, and provide a comprehensive assessment of variation within the genus. Results indicate that Heteranassa fraterna syn. n., is a junior synonym of Heteranassa mima.

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