Macracantha

Life-forms

Superregnum: Eukaryota
Cladus: Unikonta
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Protostomia
Cladus: Ecdysozoa
Cladus: Panarthropoda
Phylum: Arthropoda
Subphylum: Chelicerata
Classis: Arachnida
Ordo: Araneae
Subordo: Opisthothelae
Infraordo: Araneomorphae
Taxon: Neocribellatae
Series: Entelegynae
Superfamilia: Araneoidea

Familia: Araneidae
Subfamilia: Gasteracanthinae
Tribus: Gasteracanthini
Genus: Macracantha
Species: M. arcuata
Name

Macracantha Simon, 1864
Etymology

Greek: μακρὸς ἃκανθα (makròs àcantha), English: Large thorn.
References

Macharoenboon, K., Siriwut, W. & Jeratthitikul, E. 2021. A review of the taxonomy of spiny-backed orb-weaving spiders of the subfamily Gasteracanthinae (Araneae, Araneidae) in Thailand. ZooKeys 1032: 17–62. DOI: 10.3897/zookeys.1032.62001 Open access Reference page. [as Macracantha p. 43]
Simon, Eugène: Histoire naturelle des araignées (aranéides), Paris, Librairie encyclopédique de Roret, p. 287-8 [1].

Macracantha is a genus of Asian orb-weaver spiders recognized as containing the species, Macracantha arcuata.[2][failed verification], although some schemes also recognise inclusion of Gasteracantha hasselti in this genus. Macracantha is notable for the extremely long, curved spines on the abdomens of female members of the genus; Eugène Simon created the taxon name from the Greek words μακρός (large, long) and ἄκανθα (spine). It occurs from India and China through Southeast Asia to Indonesia.[1]
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.[3][4]

The upper surface of the female abdomen ranges from yellow[4] to red[5] or even white or black[6] 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.[7]
Taxonomy

The taxon was first described by Eugène Simon in 1864 as a subgenus of Gasteracantha,[8] and was raised to genus status in 1974 by Michel Emerit.[9]

M. arcuata was historically included in the genus Gasteracantha.[1] A 2019 study examining three mitochondrial and two nuclear genes found that M. arcuata is allied with Gasteracantha hasselti and Actinacantha globulata and that Gasteracantha is paraphyletic with respect to Macracantha, Actinacantha, and Thelacantha. The authors, however, did not propose generic reassignments based on their data.[10]
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.[5][11]

Based on a study in Singapore, the species appears to depend heavily on primary tropical forest.[12]
References

"Macracantha arcuata (Fabricius, 1793)". World Spider Catalog. Retrieved 25 August 2020.
"Gen. Macracantha Simon, 1864". World Spider Catalog. Natural History Museum Bern. Retrieved 25 August 2020.
Tikader, B.K. (1982). The Fauna of India - Spiders: Araneae Vol. II. Calcutta: Zoological Survey of India. pp. 69–71.
Pocock, R.I. (1900). The fauna of British India, including Ceylon and Burma. Arachnida. London: Taylor and Francis. p. 232.
Molur, Sanjay; Daniel, B.A.; Siliwal, Manju (November 2004). "First record of Macracantha arcuata Fabricius, 1793 (Araneae: Araneidae) from Assam, India". Zoos' Print Journal. 19 (11): 1696. doi:10.11609/JoTT.ZPJ.1225.1696. Retrieved 3 August 2019.
"Observations of Macracantha arcuata". iNaturalist. Retrieved 3 August 2019.
Simon, E. (1903). "Etudes arachnologiques. 34e Mémoire. LIV. Arachnides recueillis à Sumatra par M. J. Bouchard". Annales de la Société Entomologique de France. 72: 301–302.
Simon, E. (1864). Histoire naturelle des araignées (aranéides). Paris. p. 287. doi:10.5962/bhl.title.51973.
Emerit, M. (1974). "Arachnides araignées Araneidae Gasteracanthinae". Faune Madagascar. 38: 29.
Tan, Ji; Chan, Zi Yang; Ong, Ching Ang; Yong, Hoi Sen (14 February 2019). "Phylogenetic relationships of Actinacantha Simon, Gasteracantha Sundevall, Macracantha Hasselt and Thelacantha Simon spiny orb-weavers (Araneae: Araneidae) in Peninsular Malaysia". Raffles Bulletin of Zoology. 67: 32–55. doi:10.26107/RBZ-2019-0003.
Siliwal, Manju; Molur, Sanjay (December 2005). "Some observations on the webs of Gasteracantha geminata (Fabricius, 1798) and Macracantha arcuata (Fabricius, 1793) (Araneae: Araneidae)". Zoos' Print Journal. 21 (1): 2133–2134. doi:10.11609/JoTT.ZPJ.1324.2133-4. Retrieved 3 August 2019.
"Flora Fauna Web - Animal Detail - Macracantha arcuata (Fabricius, 1793)". NParks Flora&FaunaWeb. National Parks Board, Singapore. Retrieved 3 August 2019.