No abstract

This paper provides a summary of the extensive theoretical and empirical work that has been carried out in recent years testing the adaptational significance of various spider-ant associations. Hundreds of species of spiders have evolved close relationships with ants and can be classified as myrmecomorphs, myrmecophiles, or myrmecophages. Myrmecomorphs are Batesian mimics. Their close morphological and behavioral resemblance to ants confers strong survival advantages against visually hunting predators. Some species of spiders have become integrated into the ant society as myrmecophiles or symbionts. These spider myrmecophiles gain protection against their own predators, live in an environment with a stable climate, and are typically surrounded by abundant food resources. The adaptations by which this integration is made possible are poorly known, although it is hypothesized that most spider myrmecophiles are chemical mimics and some are even phoretic on their hosts. The third type of spider-ant association discussed is myrmecophagy—or predatory specialization on ants. A table of known spider myrmecophages is provided as is information on their biology and hunting strategies. Myrmecophagy provides these predators with an essentially unlimited food supply and may even confer other protections to the spiders.

No abstract

The new genus and species Myrmecicultor chihuahuensis Ramirez, Grismado, and Ubick is described and proposed as the type of the new family, Myrmecicultoridae Ramirez, Grismado, and Ubick. The species is ecribellate, with entelegyne genitalia, two tarsal claws, without claw tufts, and the males have a retrolateral palpal tibial apophysis. Some morphological characters suggest a pos¬ sible relationship with Zodariidae or Prodidomidae, but the phylogenetic analysis of six markers from the mitochondrial (12S rDNA, 16S rDNA, cytochrome oxidase subunit I) and nuclear (histone H3, 18S rDNA, 28S rDNA) genomes indicate that M. chihuahuensis is a separate lineage emerging near the base of the Dionycha and the Oval Calamistrum clade. The same result is obtained when the molecular data are combined with a dataset of morphological characters. Specimens of M. chi¬ huahuensis were found associated with three species of harvester ants, Pogonomyrmex rugosus, Novomessor albisetosis, and Novomessor cockerelli, and were collected in pitfall traps when the ants are most active. The known distribution spans the Big Bend region of Texas (Presidio, Brewster, and Hudspeth counties), to Coahuila (Cuatro Cienegas) and Aguascalientes (Tepezala), Mexico.

The scaber group of the genus Eremobates is reviewed in terms of new characters and a more restricted biogeographic area. Three new species are described from the U.S.A.: Eremobates socal (California), E. icenoglei (California), E. corpink (Utah). We synonymize E. gladiolus Muma with E. scaber (Kraepelin); E. consors Muma, E. ascopulatus Muma and E. flavus with E. ascopulatiis Muma; and E. mimbrenus Muma with E. monuoniis (Roewer). Eremobates scaber, E. hodai Muma, E. clams Muma, E. similis Muma are now described from both sexes. All scaber species except the Mexican species, E. legalis Harvey, are now known from both sexes. We also present the first phytogeny of the species group based on morphological characters. This phytogeny demonstrates a geographic grouping into northern and southern clades.