Paraparchites pecosensis Crasquin sp. nov.

urn:lsid:zoobank.org:act: E76693E7-FD8A-4E7B-9328-6D3248AC584F

Figs 5D, 7D–H

Diagnosis

A species of Paraparchites with a small hemi-circular ridge at mid-H of PB on both valves and a weak overreach of RV above hinge-line.

Etymology

In reference to the Pecos River, West Texas, USA.

Material examined

Holotype USA • complete carapace, (Fig. 7D); Guadalupe Mountains, West Texas, Williams Ranch Member, Cutoff Formation, Quarry section, sample GM1; Roadian, Middle Permian; MNHN.F. F63404.

Paratype USA • 1 complete carapace, (Fig. 7H); Guadalupe Mountains, West Texas, Williams Ranch Member, Cutoff Formation, Quarry section, sample GM1; Roadian, Middle Permian; MNHN.F. F63408 .

Additional material

USA • 1 complete carapace; Guadalupe Mountains, West Texas, Williams Ranch Member, Cutoff Formation, Quarry section, sample GM1; Roadian, Middle Permian; MNHN.F. F63405 • 1 right valve; same locality as for preceding; Roadian, Middle Permian; MNHN.F. F63407 • 1 right valve; Guadalupe Mountains, West Texas, ‘ McKittrick Canyon’ Member, Bell Canyon Formation, MKCS1 section, sample GM6; Capitanian, Middle Permian; MNHN.F. F63406 • 1 complete carapace, 52 valves; Guadalupe Mountains, West Texas, Williams Ranch Member, Cutoff Formation, Quarry section, samples GM1, GM2, GM3; Roadian; MNHN.F. F63656 • 15 valves; same locality as for preceding; ‘ McKittrick Canyon’ Member, Bell Canyon Formation, MKCS1 section, sample 2 (GM6), Capitanian; Middle Permian; MNHN.F. F63486 .

Dimensions

L= 503–2100 µm; H= 341–1467 µm (Fig. 5D).

Description

Carapace stocky (H/L=0.69–0.75) sub-rectangular in lateral outline; DB straight at LV; DB a little convex with weak overreach of RV above hinge-line; AB and PB quite equivalent with large radius of curvature, maximum of curvature around mid-H; VB nearly straight; LV overlaps RV all around free margins; presence of small hemi-circular ridge at mid-H of PB on both valves.

Occurrence

Samples GM1, GM2, and GM3, Quarry section, Williams Ranch Member, Cutoff Formation, Roadian; sample 2 (GM6), MKCS1 section, ‘McKittrick Canyon’ Member, Bell Canyon Formation, Capitanian; Guadalupe Mountains, West Texas, USA, Middle Permian (this work).

Remarks

Paraparchites pecosensis sp. nov. has a lateral outline similar to that of Paraparchites texanus Ulrich & Bassler, 1906 emend. Scott, 1959 from the Early Permian of Texas (Scott 1959). The main difference between the two species is the small hemi-circular ridge at PB in the new species.