Polyrhachis
Encyclopedia
Polyrhachis is a genus of formicine
ants found in the Old World
with a large number of species (over 600). The genus is yet to be comprehensively resolved and contains many varied species including nest weavers (e.g. Polyrhachis dives), swimming workers (e.g. Polyrhachis sokolova
), soil (e.g. Polyrhachis proxima) and tree dwellers (e.g. Polyrhachis bicolor)!
Size: Workers range in size approx 5-10mm in length
Eyes developed, no ocelli. Antennae have 12-segments. Antennal insertions situated far from posterior margin of clypeus.
Mesosoma of most species have spines on one or more of its pronotal, mesonotal or propodeal components. Petiole armed with spines or teeth.
First gastral tergite well developed, longer in dorsal view than exposed parts of the following terga together. Opening at gastral apex for release of venom lacking a radial fringe of hairs .
Polyrhachis species include an array of nesting types ranging from terrestrial, soil based nests to arboreal nests. As a result the nest architectures also vary with some species displaying a high level of complexity to next building, utilising larval silk to weave nest materials together. Such nest weaving is more commonly associated (and indeed more complex)in ants of the genus Oecophylla.
Polyrhachis do not have a sting but with an acidipore can spray formic acid. When attacking, this is often sprayed in combination with biting thus making the acid more effective against the subject of the attack. Polyrhachis that do not possess a metapleural gland
seem to utilise the antibiotic
properties of their formic acid
and when it cannot be used, ants are more likely to succumb to parasite infection
Formicinae
Formicinae is a subfamily within the Formicidae containing ants of moderate evolutionary development.Formicines retain some primitive features such as the presence of cocoons around pupae, the presence of ocelli in workers, and little tendency toward reduction of palp or antennal segmentation in...
ants found in the Old World
Old World
The Old World consists of those parts of the world known to classical antiquity and the European Middle Ages. It is used in the context of, and contrast with, the "New World" ....
with a large number of species (over 600). The genus is yet to be comprehensively resolved and contains many varied species including nest weavers (e.g. Polyrhachis dives), swimming workers (e.g. Polyrhachis sokolova
Polyrhachis sokolova
Polyrhachis sokolova is a species of ant recently discovered to be capable of surviving tidal inundations.Researchers at the James Cook University gained attention in 2006 after finding and reporting this behavior. Polyrhachis sokolova nests in mud in mangrove swamps, regularly inundated by rising...
), soil (e.g. Polyrhachis proxima) and tree dwellers (e.g. Polyrhachis bicolor)!
General morphology
Size: Workers range in size approx 5-10mm in length
Eyes developed, no ocelli. Antennae have 12-segments. Antennal insertions situated far from posterior margin of clypeus.
Mesosoma of most species have spines on one or more of its pronotal, mesonotal or propodeal components. Petiole armed with spines or teeth.
First gastral tergite well developed, longer in dorsal view than exposed parts of the following terga together. Opening at gastral apex for release of venom lacking a radial fringe of hairs .
Ecology
Polyrhachis species include an array of nesting types ranging from terrestrial, soil based nests to arboreal nests. As a result the nest architectures also vary with some species displaying a high level of complexity to next building, utilising larval silk to weave nest materials together. Such nest weaving is more commonly associated (and indeed more complex)in ants of the genus Oecophylla.
Polyrhachis do not have a sting but with an acidipore can spray formic acid. When attacking, this is often sprayed in combination with biting thus making the acid more effective against the subject of the attack. Polyrhachis that do not possess a metapleural gland
Metapleural gland
Metapleural glands are secretory glands that are unique to ants and basal in the evolutionary history of ants. They are responsible for the production of an antibiotic fluid that then collects in in a reservoir on the posterior of the ant's alitrunk...
seem to utilise the antibiotic
Antibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...
properties of their formic acid
Formic acid
Formic acid is the simplest carboxylic acid. Its chemical formula is HCOOH or HCO2H. It is an important intermediate in chemical synthesis and occurs naturally, most notably in the venom of bee and ant stings. In fact, its name comes from the Latin word for ant, formica, referring to its early...
and when it cannot be used, ants are more likely to succumb to parasite infection