Healdia cutoffella Crasquin sp. nov.

urn:lsid:zoobank.org:act: 7615C462-45B0-4D0E-A961-7E469B332767

Figs 4D–F, 5A

Diagnosis

A species of Healdia with a short and stocky carapace and a posterior ridge more or less vertical without spines, ADB longer than PDB in both valves.

Etymology

After the Cutoff Formation, Roadian, Middle Permian, West Texas that contains this species.

Material examined

Holotype USA • complete carapace, (Fig. 4D); Guadalupe Mountains, West Texas, Williams Ranch Member, Cutoff Formation, Quarry section, sample GM4; Roadian, Middle Permian; MNHN.F. F63368.

Paratype USA • 1 complete carapace, (Fig. 4E); Guadalupe Mountains, West Texas, Williams Ranch Member, Cutoff Formation, Quarry section, sample GM1; Roadian, Middle Permian; MNHN.F. F63369 .

Additional material

USA • 1 left valve, (Fig. 4F); Guadalupe Mountains, West Texas, Williams Ranch Member, Cutoff Formation, Quarry section, sample GM4; Roadian, Middle Permian; MNHN.F. F63370 • 10 complete carapaces, 32 valves; Guadalupe Mountains, West Texas, Williams Ranch Member, Cutoff Formation, Quarry section, samples GM1, GM4; Roadian, Middle Permian; MNHN.F. F63474 .

Dimensions

L= 452–667 µm; H =300–448 µm (Fig. 5A)

Description

Short and stocky carapace, egg-shaped in lateral view; LV strongly overlaps RV all around the carapace; ADB longer than PDB at both valves; AB large with maximum of curvature located around mid-H;

PB quite equivalent to AB; presence of a posterior vertical to slightly tilted ridge, without spines; carapace laterally compressed posterior to ridge, more strongly at LV.

Occurrence

Samples GM1, GM4, Quarry section, Williams Ranch Member, Cutoff Formation, Roadian; sample 4 (GM5), MKCS1 section, ‘McKittrick Canyon’ Member, Bell Canyon Formation, Capitanian; Middle Permian, Guadalupe Mountains, West Texas, USA (this work).

Remarks

Healdia cutoffella sp. nov. is very similar to Healdia simplissima Harlton, 1933 from the Pennsylvanian of Texas and Oklahoma (Harlton 1933; Hoare & Merrill 2004). Both species have the same ridge without spines, equivalent AB and PB, but mainly differ by PB being longer than AB in H. simplissima (herein AB is longer than PB).