Anatea
Encyclopedia
Anatea formicaria is an ant-mimicking
spider, only known from the rain forest of New Caledonia
. Before 1967, it was considered to belong to the family Clubionidae. It was placed there based on the ant-like outward modifications and male genitalia, which superficially resemble those of the genus Micaria.
In fact it is closely related to the genera Euryopis and possibly Achaearanea
.
Males and females look very similar; the male is 2.5mm long.
Although the ant shape is unlikely to deceive an ant, the spider does hunt ants. The ant form is therefore probably to evade predators that would eat spiders, but not ants.
Unlike all other ant mimics from the family Theridiidae, A. formicaria mimics the ant's petiole
by an elongation of the pedicel
. In addition the dorsum
of the "petiole" is rugose and has a distinct "node", like most ants do. The abdomen
is rounded and highly shiny, mimicking an ant's gaster
. The spider mimics the 2.6 mm long myrmicine
ant Monomorium croceiventre, which lives in the same habitat. The color pattern (dark brown anterior, light, yellow brown posterior) of both is quite rare in ants, although two other myrmicine ants from the same area of rain forest (Xiphomyrma tenuicrius and Lordomyrma sp.) also show it. Myrmicine ants have large stings, this avoiding predation. The occurrence of the pattern in these three ant species could be Müllerian mimicry
, while the spider uses Batesian mimicry
(as it is palatable).
Ant mimicry
Ant mimicry is mimicry of ants by other organisms. Ants are abundant all over the world, and insect predators that rely on vision to identify their prey such as birds and wasps normally avoid them, either because they are unpalatable, or aggressive. Thus some other arthropods mimic ants to escape...
spider, only known from the rain forest of New Caledonia
New Caledonia
New Caledonia is a special collectivity of France located in the southwest Pacific Ocean, east of Australia and about from Metropolitan France. The archipelago, part of the Melanesia subregion, includes the main island of Grande Terre, the Loyalty Islands, the Belep archipelago, the Isle of...
. Before 1967, it was considered to belong to the family Clubionidae. It was placed there based on the ant-like outward modifications and male genitalia, which superficially resemble those of the genus Micaria.
In fact it is closely related to the genera Euryopis and possibly Achaearanea
Achaearanea
Achaearanea is a genus of spiders in the Theridiidae family.-Taxonomy:This genus used to include the extremely abundant common house spider, which was transferred to genus Parasteatoda in 2006, together with many other species. A. veruculata and many more species were moved to genus Cryptachaea in...
.
Males and females look very similar; the male is 2.5mm long.
Although the ant shape is unlikely to deceive an ant, the spider does hunt ants. The ant form is therefore probably to evade predators that would eat spiders, but not ants.
Unlike all other ant mimics from the family Theridiidae, A. formicaria mimics the ant's petiole
Petiole (insect)
In entomology, the term petiole is most commonly used to refer to the constricted first metasomal segment of members of the Hymenopteran suborder Apocrita; it may be used to refer to other insects with similar body shapes, where the metasomal base is constricted...
by an elongation of the pedicel
Pedicel (spider)
The pedicel of a spider is a small, flexible cylinder that joins the cephalothorax and abdomen. This helps the spider to spin silk without moving the cephalothorax....
. In addition the dorsum
Dorsum
Dorsum is a Latin word. In science, it could mean:* Dorsum , the posterior side of an animal* Dorsum , a term used in astrogeology for a ridge* Theta Capricorni, a star on the back of the Goat...
of the "petiole" is rugose and has a distinct "node", like most ants do. The abdomen
Abdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...
is rounded and highly shiny, mimicking an ant's gaster
Gaster
The gaster is the bulbous posterior portion of the metasoma found in Apocrita Hymenoptera . This begins with abdominal segment III on most ants, but some make a postpetiole out of segment III, in which case the gaster begins with abdominal segment IV....
. The spider mimics the 2.6 mm long myrmicine
Myrmicinae
Myrmicinae is a subfamily of ants. There are about 140 genera within the group, with the family being cosmopolitan. The pupae lack cocoons. Some species retain a functional sting. The petioles of Myrmicinae consist of two nodes...
ant Monomorium croceiventre, which lives in the same habitat. The color pattern (dark brown anterior, light, yellow brown posterior) of both is quite rare in ants, although two other myrmicine ants from the same area of rain forest (Xiphomyrma tenuicrius and Lordomyrma sp.) also show it. Myrmicine ants have large stings, this avoiding predation. The occurrence of the pattern in these three ant species could be Müllerian mimicry
Müllerian mimicry
Müllerian mimicry is a natural phenomenon when two or more harmful species, that may or may not be closely related and share one or more common predators, have come to mimic each other's warning signals...
, while the spider uses Batesian mimicry
Batesian mimicry
Batesian mimicry is a form of mimicry typified by a situation where a harmless species has evolved to imitate the warning signals of a harmful species directed at a common predator...
(as it is palatable).