Definition
Arachnura melanura is a species of orb‑weaving spider in the family Araneidae, commonly referred to as the black‑tailed orb‑weaver.
Overview
Arachnura melanura is distributed throughout parts of South and Southeast Asia, with confirmed records from India, Sri Lanka, Bangladesh, Myanmar, Thailand, and Malaysia. The species inhabits a variety of habitats, including forest edges, gardens, and agricultural fields, where it constructs vertical orb webs to capture flying insects. Like other members of the genus Arachnura, it is noted for the distinctive elongated, tail‑like extension of the abdomen, which gives the spider its common name.
Etymology / Origin
The generic name Arachnura derives from the Greek words “arachne” (spider) and “oura” (tail), referencing the characteristic tail‑shaped abdomen of these spiders. The specific epithet melanura combines the Greek “melas” (black) and “oura” (tail), indicating a dark‑colored tail. The species was originally described by Ludwig Carl Christian Koch in 1872.
Characteristics
- Morphology: Adult females typically measure 8–12 mm in body length, while males are smaller, about 5–7 mm. The abdomen is markedly elongated into a slender, tapering tail that is darker than the posterior abdomen, often appearing black or deep brown. The cephalothorax and legs are generally pale yellow to light brown, with fine setae.
- Sexual dimorphism: Females possess the prominent tail; males have a reduced or absent tail and are less conspicuous.
- Web: Constructs a vertical, circular orb web with sticky capture spirals. The web is often positioned near vegetation or low‑lying structures.
- Behavior: Primarily nocturnal; females remain on the web during night hours to capture prey, retreating to a hidden retreat during the day. Egg sacs are attached to the web or nearby foliage.
- Reproduction: Mating occurs in the spring and early summer. Females lay several egg sacs, each containing dozens of eggs that hatch after approximately two weeks, depending on temperature and humidity.
Related Topics
- Arachnura – the genus encompassing tail‑shaped orb‑weavers, comprising roughly 15 recognized species.
- Araneidae – the family of orb‑weaving spiders, noted for their characteristic wheel‑shaped webs.
- Orb‑weaving spiders – a diverse group of spiders that build orb‑shaped capture webs.
- Sexual dimorphism in spiders – the phenomenon of marked differences in size and morphology between male and female spiders, common in many Araneidae species.
References: World Spider Catalog (2024), Natural History Museum data, regional faunal surveys of South and Southeast Asian arachnids.