Agnostida

Itagnostus interstrictus

Order Agnostida / Suborder Agnostina / Superfamily Agnostoidea / Family Peronopsidae

Cambrian, Miaolingian, DrumianUSA

Itagnostus interstrictus — photo 1 — Photo 1 · Specimen with appendages preserved (USA; Lerosey-Aubril et al., Holotype USNM15405 (USA; Palmer 1954) Illustrated specimens (USA; Robison 1964) 2020) Hypostome specimen (USA; Robison (USA; Robison 1964) 1972) Complete dorsal shield on a slab (USA; (USA; Xuanling) Baiya)

Itagnostus interstrictus — photo 2 — Photo 2 · Specimen with appendages preserved (USA; Lerosey-Aubril et al., Holotype USNM15405 (USA; Palmer 1954) Illustrated specimens (USA; Robison 1964) 2020) Hypostome specimen (USA; Robison (USA; Robison 1964) 1972) Complete dorsal shield on a slab (USA; (USA; Xuanling) Baiya)

Itagnostus interstrictus — photo 3 — Photo 3 · Specimen with appendages preserved (USA; Lerosey-Aubril et al., Holotype USNM15405 (USA; Palmer 1954) Illustrated specimens (USA; Robison 1964) 2020) Hypostome specimen (USA; Robison (USA; Robison 1964) 1972) Complete dorsal shield on a slab (USA; (USA; Xuanling) Baiya)

Itagnostus interstrictus — photo 4 — Photo 4 · Specimen with appendages preserved (USA; Lerosey-Aubril et al., Holotype USNM15405 (USA; Palmer 1954) Illustrated specimens (USA; Robison 1964) 2020) Hypostome specimen (USA; Robison (USA; Robison 1964) 1972) Complete dorsal shield on a slab (USA; (USA; Xuanling) Baiya)

Itagnostus interstrictus — photo 5 — Photo 5 · Specimen with appendages preserved (USA; Lerosey-Aubril et al., Holotype USNM15405 (USA; Palmer 1954) Illustrated specimens (USA; Robison 1964) 2020) Hypostome specimen (USA; Robison (USA; Robison 1964) 1972) Complete dorsal shield on a slab (USA; (USA; Xuanling) Baiya)

Itagnostus interstrictus — photo 6 — Photo 6 · Specimen with appendages preserved (USA; Lerosey-Aubril et al., Holotype USNM15405 (USA; Palmer 1954) Illustrated specimens (USA; Robison 1964) 2020) Hypostome specimen (USA; Robison (USA; Robison 1964) 1972) Complete dorsal shield on a slab (USA; (USA; Xuanling) Baiya)

Itagnostus interstrictus — photo 7 — Photo 7 · Specimen with appendages preserved (USA; Lerosey-Aubril et al., Holotype USNM15405 (USA; Palmer 1954) Illustrated specimens (USA; Robison 1964) 2020) Hypostome specimen (USA; Robison (USA; Robison 1964) 1972) Complete dorsal shield on a slab (USA; (USA; Xuanling) Baiya)

Classification

Order Agnostida / Suborder Agnostina / Superfamily Agnostoidea / Family Peronopsidae

Genus

Itagnostus

Genus author

Ö pik A. A.

Genus etymology

it, itos, Greek, passable, traversable; Agnostus, a trilobite genus name.

Species

I. interstrictus (White, 1874)

Species author

White C. A.

Species etymology

interstric, interstricus, gathered together.

Age

Cambrian, Miaolingian, Drumian

Distribution

USA

Synonyms

Agnostus interstrictus; Peronopsis(Armagnostus)interstrictus; Euagnostus interstrictus; Peronopsis interstrictus Peronopsis interstricta

Diagnosis

Cephalon and pygidium broadly rounded. Anterior end of glabellar frontal lobe rounded; posterior lobe swollen, with obscure glabellar node medially; basal lobe equilateral-triangular; border broad; border furrow deep; preglabellar field relatively broad; preglabellar median furrow absent. Pygidial axis relatively narrow and long, slightly narrowing medially, with an axial node at the constriction; with postaxial median furrow; pygidial border broad; border furrow deep; with a pair of short lateral spines.