Pentagnostus

Pentagnostus is a genus of trilobites restricted to the Middle Cambrian. Its remains have been found in Siberia, Australia, North America, Scandinavia, and Kazakhstan.

Taxonomy
The probable ancestor of Pentagnostus is Archaeagnostus. Two subgenera can be distinguished. The nominate subgenus occurred first and developed into the later subgenus Pentagnostus (Meragnostus) and the family Ptychagnostidae.

Subgenus Pentagnostus (Pentagnostus)

 * P. anabarensis Lermontova, 1940 (type)
 * P. ademptus (Prokovskaya and Jegorova, 1972)
 * P. brighamensis (Resser, 1938)
 * P. shergouldi Laurie, 2004
 * P. veles Öpik, 1979 synonym P. endemicus.

Subgenus Pentagnostus (Meragnostus)

 * P. bonnerensis (Resser, 1939) (type) synonyms P. admirabilis and Agnostus lautus.
 * P. bulkurensis (Prokovskaya and Pregel, 1982)
 * P. remotus (Prokovskaya and Jegorova, 1969)
 * P. segmentus (Robison, 1964)
 * P. shabactensis Ergaliev, 2008 synonym Peronopsis ultima Ergaliev, 1980 non Poulsen 1960.