Troglohyphantes gracilis

Template:Short description Template:Speciesbox Troglohyphantes gracilis is a species of spider in the family Linyphiidae that is endemic to Slovenia, living in caves in the Kočevje mountains. It is a relatively small spider, between in length. It is generally reddish-orange with a pattern of arrow-shaped lines on its abdomen. The species is one of three, alongside Troglohyphantes similis and Troglohyphantes spinipes that are found in contiguous ranges, which are sometimes referred to as the Kočevje subterranean spider. It can be distinguished from its relatives by its copulatory organs, including the shape of the female's epigyne and the presence of a short straight projection, or apophysis, on the male's palpal bulb.

Taxonomy

Troglohyphantes gracilis is a species of sheet weaver spiders, members of the family Linyphiidae, that was first described by Louis Fage in 1919. He allocated the species to the genus Troglohyphantes, which had been circumscribed by Gustav Joseph in 1881.Template:Sfn The genus has specialised in living in caves, with reduced vision, some species losing their eyes, and slower development.Template:Sfn It is a member of a group called croaticus within the genus, which is itself part of the subgenus Troglohyphantes.Template:Sfn

Description

Like all the members of the genus, Troglohyphantes gracilis is a relatively small spider.Template:Sfn The female has a body length between and a cephalothorax long and between wide.Template:Sfn It is very similar in shape to Troglohyphantes similis.Template:Sfn The spider is reddish-orange, similar to Troglohyphantes spinipes, but it is lighter. The pattern on the top, which consists of five light arrow-shaped lines on the spider's abdomen, is also lighter.Template:Sfn The spider's epigyne, the external and most visible of its copulatory organs, is similar to Troglohyphantes spinipes, but it is not as wide.Template:Sfn

The male is similar to the female, typically in length. Its cephalothorax is generally smaller, typically 1.34 mm long and wide.Template:Sfn It has multiple spines on its legs, incljuding five on the tibia.Template:Sfn Its palpal bulb is similar to the related Troglohyphantes spinipes but the species differ in the existence of a shorter and straighter projection, or apophysis, that projects from the palpal bulb and differences in the shape of the lamella.Template:Sfn

Distribution and habitat

Most Troglohyphantes species live in the mountain ranges of Europe including the Pyrenees, Alps, Dinarides and Carpathians, usually in subterranean environments or caves.Template:Sfn Troglohyphantes gracilis lives in three caves in the Kočevje mountains of Lower Carniola, Slovenia.Template:Sfn Troglohyphantes similis, Troglohyphantes spinipes and this species are very closely related with ranges that are contiguous.Template:Sfn The three species are all referred to as the Kočevje subterranean spider.Template:Sfn The species is at risk of climate change reducing its habitat.Template:Sfn