Tetragnathidae  

The spider family Tetragnathidae (longjawed orb weavers) includes 966 described species (Platnick 2014), with around three dozen of these occurring in North America north of Mexico (Levi 2005; Platnick 2014).

Tetragnathids typically have long, thin bodies and legs, with the first pair of legs the longest and the third pair the shortest. The cheliceral bases and fangs are elongated. The male's palps are long and thin as well. The front two pairs of legs are often stretched out in front of the body, especially when the spider is at rest. During mating, the male and female tightly interlock their large jaws, but the long palps of the male are able to reach the female's reproductive opening even in this position. (Bradley 2013)  Like most spiders, tetragnathids have eight eyes.

Most tetragnthids spin orb webs to capture prey. These webs are often oriented horizontally with an open hub. Many species build their webs near water or in vegetation above it, capturing emerging insects such as mosquitos. One exception is Leucauge, which often build webs at an oblique angle to the horizontal, often well away from water. Their conspicuous webs and silvery and green colors often make these spiders easy to notice. Nephila constructs vertical, bright yellow webs. Meta builds in dark places such as in caves or wells. Pachygnatha builds only in very early instars, in later stages becoming wandering hunters. (Levi 2005; Bradley 2013)

Tetragnathidae have been transferred in and out of the old families Epeiridae and Argiopidae, as well as the present-day Araneidae. Levi (1980, 1981) revised and illustrated the North American species (subsequently, Marusik and Koponen [1992] determined that the North American Meta "menardi" is distinct from the European species and gave it a new name, "M. americana" but Dondale [1995] found an earlier name, with priority, for the American Meta, M. ovalis).

Most tetragnathid males have conspicuously enlarged chelicerae, often armored with numerous teeth. Some of these teeth, along with specialized cheliceral apophyses, play an important role during courtship and copulation as they are involved in a behavior known as cheliceral clasp (Bristowe, 1958; Eberhard and Huber, 1998). Other characters common to most tetragnathids are the close association of the embolus and conductor in the male palp, the presence of conspicuous trichobothria on the fourth leg femur and juxtaposed lateral eyes. Nevertheless, morphological features vary considerably within the family and there are several species that differ from the typical tetragnathid morphology. Females of the majority of tetragnathid genera have entelegyne genitalia, but the members of the subfamily Tetragnathinae provide a remarkable exception: all tetragnathines are secondarily haplogyne.

Tetragnatha javana. Left: male chelicerae frontal. Right: female chelicerae, frontal. Note the numerous teeth and cheliceral apophyses on the male chelicerae. Images © 2008 Dimitar Dimitrov

Most tetragnathids build orb webs of similar architecture, often with open hubs. Pachygnatha species have abandoned web building as a hunting strategy and actively search for food wandering around.

Two Leucauge species feeding in their webs. Left: Leucauge celebesiana. © 2007 Amir Ridhwan. Right: Leucauge venusta. © 2008 Jerry Oldenettel

Barcode of Life Data Systems (BOLD) Stats