Like all members of the suborder Agnostida, Glyptagnostus reticulatus is completely blind and only has two thoracic segments.

The border of the pygidium is also well-defined, widening towards the back, and with short, backward facing marginal spines.

[2] Like other members of the genus, the cephalon always exhibits a pair of kidney-shaped lumps next to the front glabellar lobe.

The third subspecies, Glyptagnostus reticulatus nodulosus was proposed by the Swedish paleontologist Anton Hilmar Westergård in 1947, but it has generally not been accepted by other authors.

Glyptagnostus reticulatus angelini also has poorly developed longitudinal furrows outlining the pygidial axis and a variable degree of reticulation.

He also noted that Palmer acknowledged a complete evolutionary gradation between the two subspecies, and thus doubted the utility of establishing formal diagnoses for both.

The genus Ptychagnostus was retained as if Jaekel described it with Agnostus punctuosus as the type species, while Glyptagnostus remains valid.

Its first appearance at the GSSP section of the Huaqiao Formation in Hunan, China is defined as the beginning of the Paibian Age (around 497 million years ago) and of the Furongian Epoch (Upper Cambrian).