Salticidae Emertonius

Emertonius exasperans (Peckham & Peckham, 1892)

Emerton’s Ant Jumper

E. exasperans is instantly recognisable in the field by the profile of its carapace, and its strikingly pattern and contrasting colouration. The anterior one-third of the thoracic region is slightly below the flat cephalic region while the posterior two-thirds drop steeply from its dorsal edge to form a concave slope (in side view) to the posterior margin. A narrow median stripe of short black bristles can be seen on the slope.

In both sexes, the black abdomen is adorned with a single patch of whitish setae at the posterior end, and several lobe-shaped patches of yellowish setae fanning out from its anterior edge. The median pair of the anterior lobes are club-shaped and joined at the base (appearing like a butterfly) in the male, but in the female and sub-adult male the two lobes are separated by a patch of darker setae.

On the female carapace, there is a spear-like patch of yellowish setae between the PLE, pointing to another distinct patch of pale-coloured setae between the AME. This spear is less conspicuous on the male carapace. In some individuals, the spearhead is extended as a faint line reaching the AME while in other individuals, it stops short at the mid-point of the cephalic region.

The female and sub-adult male have enlarged black palps; they habitually rest these palps over the black chelicerae. Some males have black palps and chelicerae, while other males have brown palps and purple chelicerae. The male and female differ in the black banding of their respective legs as shown in the photographs on this and the previous page.

There are some differences in the body pattern between the Singapore males and those from Indonesia although the differences between the females are less obvious. Further research is necessary to determine if these differences are simply variations within a polymorphic and widespread species, or if they mean that the Singapore species is another species of Emertonius.

Length	♀ 6–7 mm; ♂ 6–7 mm, including chelicerae
Distribution	Unable to find parent[283] of [Banten]