Zygoballus nervosus
Introduction '''''Zygoballus nervosus''''' is a species of jumping spider which occurs in the eastern United States and Canada.Male pedipalp, scale = 0.1 mm.
Taxonomy The species was first described by the arachnologists George and Elizabeth Peckham in 1888 as ''Eris nervosus''. Arachnologist James Emerton subsequently described the species in 1891 as ''Zygoballus terrestris''. After examining the type specimen of ''Eris nervosus'', however, Emerton concluded that they were the same species. In 1909, the Peckhams renamed the species ''Zygoballus nervosus'' and synonymized the previous names.
Distribution In 1909, the Peckhams reported that the species had been collected from Maine, Massachusetts, Connecticut, New York, Virginia, and Illinois. Later records report the species from Georgia, Florida, Minnesota, eastern and central Texas, Ohio, Kansas, Louisiana, and Quebec. The range of ''Z. nervosus'' overlaps with that of two other ''Zygoballus'' species, ''Z. sexpunctatus'' and ''Z. rufipes''.
Diagnosis The male ''Zygoballus nervosus'' can be distinguished from ''Z. sexpunctatus'' by its lack of a large spot of white scales at the beginning of the thoracic slope. It also lacks the thick covering of white scales on the sides of the carapace which extend from the clypeus to beyond the posterior median eyes in ''Z. sexpunctatus''.The male ''Z. nervosus'' can be distinguished from ''Z. rufipes'' by its wider, heavier cephalothorax, its shorter chelicerae, and its longer, narrower hammer-like process on the chelicerae. In addition, the thoracic slope is not as steep as in ''Z. rufipes''.The legs and pedipalps of the male ''Z. nervosus'' are shorter and thicker than those of ''Z. rufipes'' or ''Z. sexpunctatus''. The tibia of the anterior legs are typically 2½ times as long as wide, compared to about 4 times in ''Z. sexpunctatus'' or 4 to 6 times in ''Z. rufipes''.The female ''Z. nervosus'' can be distinguished by the distinct form of the epigyne, which has its openings towards the front and very close together.
Description Adult females are 3 to 4 mm in body length, while males are 2.5 to 4.5 mm. The sides of the cephalothorax are nearly vertical in front, and more rounded in the back. The ocular area occupies nearly three-fifths of the length of the cephalothorax and is widest at the posterior lateral eyes (PLE). The anterior median eyes (AME) are twice as large as the anterior lateral eyes (ALE), while the PLE are roughly the same size as the ALE.
References
External links * ''Zygoballus nervosus'' at Worldwide database of jumping spiders* ''Zygoballus nervosus'' at Salticidae: Diagnostic Drawings Library* ''Zygoballus nervosus'' at Bugguide.net