Anoria? bessus (Walcott, 1916a), 1935

Foster, John R., 2022, Continuous character variation within the Glossopleura-Anoria-Sonoraspis plexus: Dolichometopid trilobites from the Cadiz Formation (Cambrian: Miaolingian, Wuliuan), California, Palaeontologia Electronica (a 18) 25 (2), pp. 1-25 : 19

Anoria? bessus (Walcott, 1916a)

Dolichometopus? bessus Walcott, 1916a, p. 362 – 363, pl. 51, figs. 3, 3a–c.

Anoria bessus (Walcott) Resser, 1935, p. 10 , p. 54, pl. 9, fig. 2.

Anoria baton (part) Schwimmer, 1973, pl. 6, fig. 3.

Type specimens. USNM 62699 , nearly complete specimen ; USNM 62700 , pygidium ; USNM 62701 , cephalon with hypostome .

Occurrence. Gordon Shale, Montana; Bright Angel Formation, Grand Canyon (Grand Wash Cliffs), Arizona; Glossopleura Assemblage Biozone, Interval Biozone (Morgan, 2021) undesignated, (Wuliuan, Miaolingian).

Material examined. USNM 62699, USNM 62700, USNM 62701, DMNH EPI.42915, DMNH EPI.42916, USNM uncataloged (in Schwimmer, 1973).

Remarks. Species characterized by short to long eyes, reduced oval pygidium smaller than cephalon, and moderately elongate pleural spines on all thoracic segments. This latter character contrasts with the short pleural spines of most species of Glossopleura and the elongate fifth thoracic pleural spines of G. lodensis and the type material of Anoria tontoensis . These features are pronounced in USNM 62699 and the uncataloged specimen illustrated by Schwimmer (1973). Despite qualitatively moderately short eyes in the Gordon Shale specimens, most specimens have moderate to long eyes except USNM 62699 (EL/GL of 0.298 versus 0.428 in Schwimmer’s, 1973, USNM uncataloged and 0.446 in DMNH EPI.42915). Thus, all but one specimen featuring moderately elongate pleural spines and a small, oval pygidium from the Gordon and Bright Angel formations, typical of Anoria bessus , actually have elongate eyes that fit within the range of Glossopleura . Because the single anomalous, short-eyed specimen (USNM 62699) is the most complete of the cotypes, all the studied material here is designated Anoria? bessus . The question of whether the species is better placed in Glossopleura (despite the short-eyed USNM 62699 and considering the results of this study regarding eye length) is left for a separate investigation.