''Macracantha'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of Asian orb-weaver spiders recognized as containing the species, ''Macracantha arcuata''., although some schemes also recognise inclusion of ''

Gasteracantha hasselti ''Macracantha hasselti'', commonly known as Hasselt's spiny spider, is a species of spider belonging to the family Araneidae. It is a native of Asia, occurring from India eastwards to Indonesia. Typical of this genus, the male of this species is ...

'' in this genus. ''Macracantha'' is notable for the extremely long, curved spines on the abdomens of female members of the genus;

Eugène Simon Eugène Louis Simon (; 30 April 1848 – 17 November 1924) was a French naturalist who worked particularly on insects and spiders, but also on birds and plants. He is by far the most prolific spider taxonomist in history, describing over 4, ...

created the taxon name from the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

words (large, long) and (spine). It occurs from India and China through Southeast Asia to

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...

Description

The females of this genus have tough, shell-like abdomens armed with three pairs of spines. The spectacular middle (median) spines project upward and outward, curving in toward each other along their length. They are up to three times as long (20–26 mm) as the abdomen is wide (8–9 mm). The front (anterior) and rear (posterior) spines are short, relatively inconspicuous, and roughly equal in length. The upper surface of the female abdomen ranges from yellow to red or even white or black and is marked with black sigilla. The ventral surface of the abdomen bears yellow or orange marks, and the median spines can show a bluish iridescence. The male of the species measures only 1.5 mm, with stout, conical spines.

Taxonomy

The taxon was first described by

in 1864 as a subgenus of ''

Gasteracantha ''Gasteracantha'' is a genus of orb-weaver spiders first named by Carl Jakob Sundevall in 1833. Species of the genus are known as spiny-backed orb-weavers, spiny orb-weavers, or spiny spiders. The females of most species are brightly colored wi ...

'', and was raised to genus status in 1974 by Michel Emerit. ''M. arcuata'' was historically included in the genus ''Gasteracantha''. A 2019 study examining three

mitochondrial A mitochondrion (; ) is an organelle found in the cells of most Eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is use ...

and two

nuclear Nuclear may refer to: Physics Relating to the nucleus of the atom: * Nuclear engineering *Nuclear physics *Nuclear power *Nuclear reactor *Nuclear weapon *Nuclear medicine *Radiation therapy *Nuclear warfare Mathematics *Nuclear space *Nuclear ...

genes found that ''M. arcuata'' is allied with ''

'' and ''

Actinacantha globulata ''Actinacantha'' is a genus of Southeast Asian orb-weaver spiders containing the single species, ''Actinacantha globulata''. It was first described by Eugène Simon in 1864, and has only been found in Indonesia Indonesia, officially the ...

'' and that ''Gasteracantha'' is

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

with respect to ''Macracantha'', ''Actinacantha'', and ''Thelacantha''. The authors, however, did not propose generic reassignments based on their data.

Ecology

Female ''M. arcuata'' build orb webs three or four feet wide in forested areas. These webs have hollow hubs and white silk beads on the radial threads. Siliwal and Molur report that females were more often observed on the underside of leaves near their webs than hanging in the center of the web. Based on a study in Singapore, the species appears to depend heavily on primary

tropical forest Tropical forests (a.k.a. jungle) are forested landscapes in tropical regions: ''i.e.'' land areas approximately bounded by the tropic of Cancer and Capricorn, but possibly affected by other factors such as prevailing winds. Some tropical fores ...

References

External links

* {{Taxonbar, from=Q18510781, from2=Q146884 Araneidae Monotypic Araneomorphae genera Taxa named by Eugène Simon