Plutonides Hicks, 1895

Unger, Tanja, Hildenbrand, Anne, Stinnesbeck, Wolfgang & Austermann, Gregor, 2022, Biostratigraphy and taxonomy of polymerid trilobites of the Manuels River Formation (Drumian, middle Cambrian), Newfoundland, Canada, Geodiversitas 44 (33), pp. 1051-1087 : 1070

Genus Plutonides Hicks, 1895

Plutonides Hicks, 1895: 230 , 231. —

Type species: Plutonia sedgwickii Hicks, 1871 , designated by Whittington et al. (1997).

Plutonia Hicks, 1869: 69 . —

Type species: Plutonia sedgwickii Hicks, 1871 , by monotypy.

Paradoxides (Mawddachites) Fletcher, 2007: 47 . —

Type species: Paradoxides hicksii Salter, 1866b , by original designation ( Fletcher 2007).

DIAGNOSIS. — Surface ornamented; glabella widest at S4 furrow, frontal margin bluntly pointed; S2 to S4 present; palpebral lobes oblique, extending from S1 to S4; posterior section of facial suture sigmoidal; thorax with 19 segments; pygidium with one axial ring (based on Hicks 1869; Whittington et al. 1997, with modifications).

REMARKS

Plutonia was first described by Hicks (1869) but the name Plutonia was used by Stabile (1864) for a genus of Mollusca. Therefore, Hicks (1895) renamed the genus Plutonides which is still recognized today. Fletcher (2007) introduced the subgenus Paradoxides (Mawddachites) based on ‘ Paradoxides hicksii ’ as type species. His diagnosis only includes Pl. hicksii . Diagnostic characteristics presented by the author included a glabella widest at S4, deep S1 to S4 furrows, palpebral lobes extending from the base of L5 to S1, a pygidium almost circular in outline and an exoskeleton ornamented with fine anastomosing venation or granulation. These characteristics match those given byWhittington et al. (1997) for Plutonides , e.g. the characteristic glabella widening to L4, well defined S2 to S4 furrows, palpebral lobes from L1 or S1 to S4, pygidium subhexagonal and a coarsely granulose surface with meshlike pattern of fine, anastomosing ridges. We therefore interpret Paradoxides (Mawddachites) as a synonym of Plutonides . The distinctly narrow occipital ring and the relatively narrow librigena extending backward into a long curving spine, as mentioned by Fletcher (2007) for Pa. ( Mawddachites ), are here considered not to be diagnostic. Hicks (1869) already mentioned a close relationship between Plutonides and Paradoxides , but the author still referred to Plutonides as differing by its ornamentation of tubercles, unusual position of the eye suture and straight thoracic pleurae. Fletcher et al. (2005) ranked Plutonides as subgenus of Paradoxides , but this view is not followed here. Plutonides does not have a transglabellar S2 furrow, which is characteristic for Paradoxides . Other diagnostic differences in Plutonides are a shorter palpebral lobe and a bluntly pointed frontal margin compared to a rounded in Paradoxides . They clearly mark the separation of the genus Plutonides from Paradoxides .