Sphaeroderma testaceum

Sphaeroderma testaceum, the artichoke beetle, is a species of flea beetle in the family Chrysomelidae.^[1][2]

Sphaeroderma testaceum
Sphaeroderma testaceum. Dorsal view
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Coleoptera
Suborder:	Polyphaga
Infraorder:	Cucujiformia
Family:	Chrysomelidae
Genus:	Sphaeroderma
Species:	S. testaceum
Binomial name
Sphaeroderma testaceum (Fabricius, 1775)
Synonyms
Altica testacea Fabricius, 1775 Haltica cardui Gyllenhal, 1813 Sphaeroderma cardui (Gyllenhal, 1813)

Distribution

This species is present in most of Europe,^[3] North Africa and Israel.^[4] It is adventive in Northern America (Atlantic Canada),^[5][6]

Habitat

These beetles mainly inhabit wasteland, woodland, roadsides and other areas where host plants occur.^[7]

Description

Side view

Sphaeroderma testaceum can reach a size of 3.5–4 millimetres (0.14–0.16 in).^[5] These tiny beetles have a wide head, large eyes and the filiform antennae are close together between the eyes. Elytra are convex and slightly elongate and hind femora are rather enlarged. The pronotum shows coarse puncturation basally, prominent anterior corners, a well defined basal groove and two lateral notches.^[8] Elytra and pronotum are shiny light brown-orange.^[4]

This species is very similar to Sphaeroderma rubidum (Graëlls, 1853). It can be distinguished from the previous one on the basis of a smaller size and quadrate elytra,^[8] but especially with a close study of the genitalia.

Mounted specimen

Biology

Adults can be found from May/June to September. Pupation occurs in the spring and new adults may be seen from May. Overwintering occurs as 3rd (final) instar larvae, sometimes as imago.^[9]

Both larvae and adults feed on leaves, especially on various species of Thistle (Carduus, Carlina, Cirsium, Onopordum and Cynara species), on Common Knapweed (Centaurea nigra), on Serratula species and on Cirsium arvense (in Canada).^[6][7]

Bibliography

• Anderson, R., Nash, R. & O'Connor, J.P.. 1997, Irish Coleoptera: a revised and annotated list, Irish Naturalists' Journal Special Entomological Supplement, 1-81
• du Chatenet, G, 2000, Coléoptères Phytophages D'Europe, NAP Editions,
• Johnson, F.W & Halbert, J.N, 1902, A list of the Beetles of Ireland, Proceedings of the Royal Irish Academy, 6B: 535-827
• Joy, N.H., 1932, A practical handbook of British beetles, H.F. & G. Witherby,