''Ordgarius sexspinosus'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

spider Spiders ( order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species ...

in the

orb-weaver spider Orb-weaver spiders are members of the spider family Araneidae. They are the most common group of builders of spiral wheel-shaped webs often found in gardens, fields, and forests. The English word "orb" can mean "circular", hence the English name ...

family Araneidae, found from India to Japan and Indonesia. ''O. sexspinosus'' is a

bolas spider A bolas spider is a member of the orb-weaver spider (family Araneidae) that, instead of spinning a typical orb web, hunts by using one or more sticky "capture blobs" on the end of a silk line, known as a " bolas". By swinging the bolas at flyin ...

. Rather than using a web, adult females catch their prey by using a line with one or two sticky drops (a "

bolas Bolas or bolases (singular bola; from Spanish and Portuguese ''bola'', "ball", also known as a ''boleadora'' or ''boleadeira'') is a type of throwing weapon made of weights on the ends of interconnected cords, used to capture animals by entan ...

") which they swing.

Description

The adult female of ''Ordgarius sexspinosus'' has a body length of about 7–10 mm. The

carapace A carapace is a Dorsum (biology), dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tor ...

is about 3.6–3.7 mm long. It is dark brown and has six projections (tubercules). Two are arranged in the centre of the cephalic (head) part of the

cephalothorax The cephalothorax, also called prosoma in some groups, is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. (The terms ''prosoma'' and ''opisthosoma'' are equivalent to ''cepha ...

, the larger behind the smaller. Four are arranged in a transverse row in the thoracic part, two projecting forwards and two slightly behind projecting sideways. The legs are yellowish brown with brown rings. The first leg is the longest. The abdomen is usually longer (up to 6.9 mm) than wide. The upper surface is grayish brown with complicated white patterns. The "shoulders" of the abdomen are humped. The

epigyne The epigyne or epigynum is the external genital structure of female spiders. As the epigyne varies greatly in form in different species, even in closely related ones, it often provides the most distinctive characteristic for recognizing species. ...

has a distinct ring, and no scape. The male has a body length of about 2 mm or less. The carapace is dark brown with black markings. The upper surface of the abdomen is also dark brown, with darker and lighter mottling. The underside of the abdomen is darker and has a pair of white spots. The

embolus An embolus (; plural emboli; from the Greek ἔμβολος "wedge", "plug") is an unattached mass that travels through the bloodstream and is capable of creating blockages. When an embolus occludes a blood vessel, it is called an embolism or emb ...

of the

palpal bulb The two palpal bulbs – also known as palpal organs and genital bulbs – are the copulatory organs of a male spider. They are borne on the last segment of the pedipalps (the front "limbs" of a spider), giving the spider an appearance often descr ...

is spine-like.

Taxonomy

''Ordgarius sexspinosus'' was first described by

Tamerlan Thorell Tord Tamerlan Teodor Thorell (3 May 1830 – 22 December 1901) was a Sweden, Swedish arachnologist. Thorell studied spiders with Giacomo Doria at the Museo Civico di Storia Naturale de Genoa. He corresponded with other arachnologists, such as Oc ...

in 1894, as ''Notocentria sex-spinosa'', the only species in his new genus ''Notocentria''. ''Notocentria'' was synonymized with ''Ordgarius'' by

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, ...

in 1895. The genus ''Ordgarius'' has been placed in the broadly defined subfamily

Cyrtarachninae Cyrtarachninae is a subfamily of spiders in the family Araneidae (orb-weaver spiders, araneids). The group has been circumscribed in several different ways. It originated as the group Cyrtarachneae, described by Eugène Simon in 1892. The group w ...

, and, as a bolas spider, would be expected to fall within the informal group of mastophorines, although not included in the

molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

study that defined this group.

Prey capture

Like the rest of the genus ''Ordgarius'', ''O. sexspinosus'' is a

, catching its prey using one or more sticky drops on a line (a "

") rather than with a web. Adult females place a few horizontal lines of silk between twigs or leaves and then hang their bolas from it. They capture prey (usually a male moth) when it approaches by whorling the bolas using a second leg. There is evidence to suggest that, like related genera, ''Ordgarius'' can produce a mimic of the

sex pheromone Sex pheromones are pheromones released by an organism to attract an individual of the same species, encourage them to mate with them, or perform some other function closely related with sexual reproduction. Sex pheromones specifically focus on ind ...

used by a female moth to attract a male.

References

{{taxonbar, from1=Q2776905 Araneidae Spiders of Asia Spiders described in 1894 Taxa named by Tamerlan Thorell