Thanatus formicinus

Thanatus formicinus, the diamond spider, diamondback spider or ant running crab spider, is a species of running crab spider belonging to the family Philodromidae. This species has a Holarctic distribution.^[1]

Thanatus formicinus
Thanatus formicinus
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Chelicerata
Class:	Arachnida
Order:	Araneae
Infraorder:	Araneomorphae
Family:	Philodromidae
Genus:	Thanatus
Species:	T. formicinus
Binomial name
Thanatus formicinus (Clerck, 1757)[1]
Synonyms[1]
Araneus formicinus Clerck, 1757 Aranea formicina (Clerck, 1757) Philodromus formicinus (Clerck, 1757) Aranea rhomboica Walckenaer, 1802 Thomisus rhomboicus (Walckenaer, 1802) Thanatus rhomboicus (Walckenaer, 1802) Aranea testacea Panzer, 1804 Philodromus rhombiferens Walckenaer, 1826 Thanatus nigromaculatus Kulczyński, 1885 Thanatus lycosoides Emerton, 1892 Thanatus pictus Müller & Schenkel, 1895 Thanatus canadensis Gertsch, 1933 Thanatus aridorum Šilhavý, 1940

Taxonomy

Thanatus formicinus was first formally described as Araneus formicinus in Aranei Svecici. Svenska spindlar, uti sina hufvud-slågter indelte samt under några och sextio särskildte arter beskrefne och med illuminerade figurer uplyste published in 1757 and written by the Swedish entomologist and arachnologist Carl Alexander Clerck.^[2] This species is now classified as one of36 species belonging to the genus Thanatus, a genus proposed in 1837 by Carl Ludwig Koch with Araneus formicinus designated as its type species, within the family Philidromidae.^[1]

Description

Thanatus formicinus is sexually dimorphic, although the males and females are similar in colour and pattern the male is markedly smaller than the female with a body length of 5.2mm to 7.4mm compared to the females’ body length of 6.9mm to 12mm.^[3] The abdomen is pale brown to greyish brown with a clear, white margined rhomboidal mark and there may be two slender, arced black lines at the rear. The carapace is similar in colour to the abdomen but with a light central band. The legs and palpsare aso a similar colour to the abdomen although there are few black spots on the legs. The males resemble the females in colour and markings although they are typically darker.^[4]

Distribution and habitat

Thanatus formicinus has a Holarctic distribution and is found in North America, Europe and Asia, as far east as Japan, it also occurs in Iraq, Iran, Turkey and North Africa. It has been introduced to Svalbard.^[3] In the United Kingdom the diamndback spider has always been rare and was known from three sites in southern England before 1969 but was not recorded after then until a population was discovered in Clumber Park in Nottinghamshire in 2017.^[5] This species is generally found in dry and semi-dry meadows and warm, dry forest steppes.^[3] In Britain it is found in bogs dominated by sphagnum with Molinia caerulea and some heather.^[6]