Ptychagnostus

Ptychagnostus is a genus of trilobites in the order Agnostida that lived during the Cambrian period. Their remains are rarely found in empty tubes of the polychaete worm Selkirkia.^[2] The genus probably ranged throughout the water column. It has two glabellar lobes, and three pygidial lobes.^[3]

Ptychagnostus Temporal range: Middle Cambrian PreꞒ Ꞓ O S D C P T J K Pg N
Ptychagnostus germanus
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Clade:	†Artiopoda
Class:	†Trilobita (?)
Order:	†Agnostida
Family:	†Ptychagnostidae
Genus:	†Ptychagnostus Jaekel, 1909
Synonyms[1]
Triplagnostus Linnarsson, 1869 Huarpagnostus Rusconi, 1950 Solenagnostus Whitehouse, 1936 Pentagnostus Lermontova, 1940 Aristarius Opik, 1979 Aotagnostus Opik, 1979 Acidusus Opik, 1979 Canotagnostus Rusconi, 1951 Zeteagnostus Opik, 1979

Type species

Agnostus punctuosus Angelin, 1851 from the Ptychagnostus punctuosus zone of the Alum Shale (Drumian), Sweden (by original designation). Official ruling on the conservation of accepted usage of A. punctuosus as the type species was given by the International Commission on Zoological Nomenclature, 1993.

Remarks

Ptychagnostus affinis (Brøgger 1878) ^[4] was once considered a subspecies of Ptychagnostus punctuosus.Laurie (2008) ^[5] grouped punctuosus and affinis within Ptychagnostus, but preferred to place the closely related atavus within Acidusus.

Species

• Ptychagnostus punctuosus (Type species).
• Ptychagnostus affinis (formerly Pt. punctuosus affinis)
• Ptychagnostus aculeatus
• Ptychagnostus akanthodes
• Ptychagnostus atavus
• Ptychagnostus cassis
• Ptychagnostus ciceroides
• Ptychagnostus cuyanus
• Ptychagnostus germanus
• Ptychagnostus gibbus
• Ptychagnostus hybridus
• Ptychagnostus intermedius
• Ptychagnostus michaeli
• Ptychagnostus praecurrens
• Ptychagnostus seminula