Family: Tetragnathidae

Life > Eukaryotes > Opisthokonta > Metazoa (animals) > Bilateria > Ecdysozoa > Panarthropoda > Tritocerebra > Arthropoda > Arachnomorpha > Cheliceriformes > Chelicerata > Euchelicerata > Arachnida > Araneae > Araneomorpha

This orb-weaving family was previously included in the family Araneidae but was separated due to certain morphological differences and the way in which they capture and consume their prey. The Tetragnathidae is a small family comprising 5 genera in South Africa and includes both diurnal and nocturnal species ranging in length from 5-15 mm. They pose no threat to man.

It has an enormous pair of forward projecting chelicerae armed with numerous cheliceral teeth (projections), which are exaggerated in the males. This helps them restrain the female's jaws to facilitate mating.

 

Tetragnatha sp. [image N. Larsen ]

 

Tetragnathids are cryptically coloured in shades of brown and cream and green for those species that occur amongst foliage. Unlike the Araneidae family which first wraps its prey in silk after capture and then bites it, Tetragnathidae and Nephilids first bite and then wrap, the prey being crushed by the force of their large fangs.

Until recently Clitaetra, Nephila, Nephilengys and Leucage belonged to this family but have now reverted to the Nephilidae.

The web is usually horizontally inclined over streams or bodies of water in sunlit areas. It is taken down and reconstructed daily and the spider is often found on an incomplete web. On the web the spider resembles a piece of dry grass as the front two pairs of legs are projected forward while the back pairs are projected backwards.

Genera indigenous to southern Africa

Diphya

This genus occurs in South America, China to Japan, Madagascar and only Diphya simoni in South Africa.

 

Meta (thick-jawed water spider)

Meta is a nocturnal genus that occurs in cool moist areas. One named species, Meta meruensis, is recorded from South Africa. A second unidentified species, from the Cape Peninsula, is found hanging suspended below the web, which is positioned close to the ground among rocks, or vegetation in small (100-200mm) horizontal orb-webs in heavily shaded, forested areas. It is a robust spider with a globose (round) abdomen with downward projecting chelicerae. The integument (body covering) is decorated in brown and coppery colours, the legs are banded and decorated with numerous spines. This may be a new species and is the nocturnal equivalent of Tetragnatha that occurs in sunlit situations. There may be a further species from the Langeberg in the Western Cape. Meta is Latin for "conical" or "pear shaped" referring to the abdomen.

 

Pachygnatha (thick-jawed water spider)

Pachygnatha species are reported to be web-bound as juveniles but on maturing, leave the web and become free ranging. Pachygnatha zappa is the only species recorded from South Africa. It has a body length of 4mm and occurs from Limpopo Province to equatorial Africa. The chelicerae is similar to Tetragnatha but is bulky and projects downwards. Pachygnatha is derived from the Greek "pachy" means "thick" and "gnathos" means "jaws".

 

Tetragnatha (long-jawed water spiders)

Tetragnatha is a nocturnal and sometimes diurnal spider. The integument is cryptically coloured in shades of brown, cream and green for those species that occur amongst foliage. Tetragnatha has an very elongated body. The long chelicerae projects forward with long fangs folded against it. The delicate orb-web, with few radii and spirals, is usually horizontally inclined over streams or bodies of water. The web is taken down and reconstructed daily and the spider is often found on an incomplete web. On the web the spider resembles a piece of dry grass as the front two pairs of legs are projected forward while the back pairs are projected backwards. Tetragnatha has a world distribution and is the most common genus, of the Tetragnathidae, with 14 species in South Africa. The name is derived from the Greek "tetra" means "four" and "gnathos" means "jaws"

 

Text by Norman Larsen


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