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Miagrammopes

Miagrammopes is a genus of cribellate orb weavers first described by Octavius Pickard-Cambridge in 1870. These spiders have a unique shape and only four of their original eight eyes. They spin a single line of web, actively watching and jerking the line to catch their prey.

Life style

Miagrammopes species construct a horizontal, usually single thread between two branches or twigs. The spider lays down a thick band of viscid silk and then takes up a position upside down near a point of attachment, with only the central section consisting of cribellate silk. The thread has one or a few sticky capture threads attached to it that are held under tension. The line is kept under tension and released with a snap when prey alights on the inviting line and becomes entangled.

The attack behaviour involves rapid jerking and sudden sagging of the capture thread. In some tropical species such as Miagrammopes brevicaudus, the web consists of three threads. The spider positions itself at the end of one of the upper threads and only approaches the mid-section in darkness.

The female carries the cylindrical egg-sac until the spiderlings emerge.

Description

The carapace is longer than wide, low, and weakly convex above. The cephalic region is broad and obtusely rounded in front. The thoracic region has nearly subparallel sides and is truncated behind.

The eyes are unequal in size and arranged in two unequal transverse rows. The eyes of the front row are minute or obsolete, with evidence of anterior median eyes seen in small, dark pigment spots in some specimens. The posterior row is recurved with median eyes widely separated. The clypeus is broad and sloping, equal in width to two or more diameters of the posterior median eye.

The sternum is elongated and divided into two unequal sternites seemingly joined to the carapace between second and third coxae by narrow sclerites. The abdomen is elongated, often tubular. The calamistrum is a broad lobe with the spinning field entire.

The leg formula is 1423. The legs are quite long and unequal, with the second and third pairs short and thin. The fourth pair is long and laterally compressed, while the first pair is stoutest and longest with apical segments laterally compressed. The trochanters of the first and fourth legs are strongly developed, exceeding the coxae in length. The metatarsus IV is laterally compressed with a ventral comb of short spines. The calamistrum occupies most of the length of the compressed fourth metatarsus and consists of a single, sinuous series of curved bristles set on a thin keel on the dorsal surface of the segment. The front tibiae of males often have rows of stout spines.

Species

, this genus includes 71 species:

References