Lotagnostus, Whitehouse, 1936

Taylor, John F., Loch, James D. & Repetski, John E., 2024, Taxonomy and stratigraphic distribution of Lotagnostus (Agnostida: Agnostidae) and associated trilobites and conodonts in the Upper Cambrian (Furongian) of Laurentia, Zootaxa 5422 (1), pp. 1-66 : 50

Lotagnostus aff. L. rushtoni

( Plate 6.11–6.18)

1989 Lotagnostus hedini ( Troedsson, 1937) ; Ludvigsen & Westrop in Ludvigsen, Westrop, and Kindle, pl. 1, figs 1–8 only.

Occurrence. Keithia schucherti Fauna in the Gorge Formation, Vermont, and Green Point Formation, Newfoundland.

Discussion. The sclerites assigned to this species are those illustrated from the “Main Zone” of the Gorge Formation as Lotagnostus hedini in Ludvigsen et al. (1989), but subsequently removed from that species by Westrop et al. (2011), as well as three pygidia recovered from a clast in the Bed 19 limestone conglomerate in the Global Stratotype Section for the Cambrian-Ordovician boundary at Green Point, Newfoundland ( Cooper et al., 2001). Although conodonts recovered from clasts and matrix confirm a significantly younger, Skullrockian age ( Cordylodus intermedius Zone , or younger) depositional age for Bed 19, trilobites from the clast that yielded L. aff. L. rushtoni are all Sunwaptan species characteristic of the Acheilus monile Fauna of Fortey (1983) and equivalent Keithia schucherti Fauna of Ludvigsen et al. (1989). Lotagnostus aff. L. rushtoni closely resembles L. rushtoni but has smaller and less inflated basal lobes, a wider (tr.) and more broadly rounded posteroaxis that is as wide or wider than M1, and is conspicuously bulbous in large specimens. Additionally, the pygidial border furrow is narrower, shallower, and lacks the sharp boundary with the border characteristic of L. rushtoni .