This glossary describes the terms used in the formal descriptions of arachnid

Arachnid

Arachnids are a class of joint-legged invertebrate animals in the subphylum Chelicerata. All arachnids have eight legs, although in some species the front pair may convert to a sensory function. The term is derived from the Greek words , meaning "spider".Almost all extant arachnids are terrestrial...

s.

Head and body

Cephalothorax (or prosoma): One of two body segments, towards the anterior end.Clypeus: the area of the carapace between the anterior eyes and the anterior edge.Abdomen

Abdomen

In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...

 (or opisthosoma): One of two body segments, towards the posterior end.

Legs

Coxa : first leg segment, between body and trochanter.Trochanter : second leg segment, between coxa and femurFemur : third leg segment, between trochanter and tibia.Patella: fourth leg segment, between femur and tibia.Tibia : fifth leg segment, between patella and metatarsus.Metatarsus (or basitarsus)': sixth leg segment, between tibia and tarsus.Tarsus (or telotarsus): seventh (last) leg segment, after the metatarsus.

Pedipalp

Carpoblem: the principal tibial apophysis on the male pedipalp. (Typically, this is just called the tibial apophysis.)

Eyes

ALE : anterior lateral eyes.AME : anterior median eyes.PLE : posterior lateral eyes.PME : posterior median eyes.