Aurikirkbya guadalupensis Crasquin, 2021

Tarnac, Anaëlle, Forel, Marie-Béatrice, Nestell, Galina, Nestell, Merlynd & Crasquin, Sylvie, 2021, Middle Permian ostracods (Crustacea) from the Guadalupe Mountains, West Texas, USA, European Journal of Taxonomy 770, pp. 1-60 : 16-18

Aurikirkbya guadalupensis Crasquin sp. nov.

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Figs 5B , 6A–B

Diagnosis

A species of Aurikirkbya with an additional ventral ridge parallel to the adventral ridge, extending from mid-H in the anterior part to mid-H in the posterior part of the carapace.

Etymology

After the Guadalupe Mountains, West Texas, USA, where this species has been discovered.

Material examined

Holotype USA • complete carapace, ( Fig. 6A ); Guadalupe Mountains , West Texas, Williams Ranch Member , Cutoff Formation , Quarry section, sample GM2; Roadian, Middle Permian; MNHN.F. F63383 .

Paratype USA • 1 complete carapace, ( Fig. 6B ); Guadalupe Mountains , West Texas, Williams Ranch Member , Cutoff Formation , Quarry section, sample GM1; Roadian, Middle Permian; MNHN.F. F63384 .

Additional material

USA • 8 valves; Guadalupe Mountains , West Texas, Williams Ranch Member , Cutoff Formation , Quarry section, samples GM1, GM2, and GM3; Roadian, Middle Permian; MNHN.F. F63478 .

Dimensions

L= 829–1280 µm; H= 368–660 µm ( Fig. 5B ).

Description

Carapace sub-rectangular in lateral view with Hmax located in anterior half; Lmax located in dorsal part of Hmax; DB long and straight; posterior shoulder clearly expressed, ACA close to 90° or slightly obtuse; PCA close to 90° or slightly acute; AB with large radius of curvature with maximum located around mid-H; VB almost straight with weak median concavity, parallel to DB; PB with small radius of curvature and maximum located close to DB; 2 vertical lobes connected above kirkbyan pit by small sub-horizontal lobe; kirkbyan pit located at mid-L and below mid-H; two important ridges along free margins, one ventral and one adventral; marginal structure underlined by tubercles; adventral ridge smooth as well as areas around cardinal angles; additional ridge parallel to adventral one, extending from mid-H in anterior part up to mid-H in posterior part of the carapace; presence of a dorsal shield characteristic of the genus; surface reticulate.

Occurrence

Samples GM1, GM2, and GM3, Quarry section, Williams Ranch Member, Cutoff Formation, Guadalupe Mountains, West Texas, USA, Roadian, Middle Permian (this work).

Remarks

Aurikirkbya guadalupensis sp. nov. differs from the three species described by Sohn (1950) ( A. wordensis ( Hamilton, 1942) , A. barbarae Sohn, 1950 and A. auriformis Sohn, 1950 ) from the Roadian (upper Leonardian or lower Wordian in the sense of Sohn 1950) of the Glass Mountains, Texas by a smaller PB and a diagnostic ridge. Aurikirkbya kelletae (Harlton, 1929) from the Pennsylvanian of Texas and Aurikirkbya miyakei Yanaka & Ono in Tanaka et al., 2012 from the Early Permian of Japan ( Tanaka et al. 2012) have a similar carapace shape but differ by the diagnostic ridge.

Figures

Fig. 5. Height/length scatter plots of species from the Middle Permian (Roadian, Capitanian) of the Guadalupe Mountains (West Texas, USA). A-1, A-2, A-3. Three last juvenile stages before adult.

Fig. 6 (next page). SEM micrographs of ostracods from the Middle Permian (Roadian, Quarry section, samples GM1, GM2, and GM4; Capitanian, MKCS1 section, samples 4 (GM5) and 2 (GM6)) of the Guadalupe Mountains (West Texas, USA).All specimens are temporarily housed in the collections of the Muséum national d’histoire naturelle, Paris, France (MNHN). A–B. Aurikirkbya guadalupensis Crasquin sp. nov. A. Holotype, left lateral view of a carapace, sample GM2 (MNHN.F.F63383). B. Paratype, left lateral view of a carapace, sample GM1 (MNHN.F.F63384). – C, E. Aurikirkbya wordensis (Hamilton, 1942). C. External view of a left valve, sample 2 (GM6) (MNHN.F.F63385). E. External view of a left valve, sample GM4 (MNHN.F.F63387). – D. Kirkbyella (Berdanella) cf. quadrata Croneis & Gutke, 1939, external view of a right valve, sample 4 (GM5) (MNHN.F.F63386). – F–H. Roundyella lebaensis Krömmelbein, 1958. F. External view of a left valve, sample GM4 (MNHN.F.F63388). G. External view of a right valve, sample GM4 (MNHN.F.F63389). H. External view of a right valve, sample GM1 (MNHN.F.F63390). – I–L. Hollinella (Hollinella) williamsranchensis Crasquin sp. nov. I. Holotype, external view of a right valve, sample GM1 (MNHN.F.F63391).J. External view of a right valve, sample GM1 (MNHN.F.F63392). K. Paratype, external view of a left valve, sample GM1 (MNHN.F.F63393). L. External view of a left valve, sample GM4 (MNHN.F.F63394). – M. Glyptopleura sp., external view of a right valve, sample GM1 (MNHN.F.F63395). – N–P. Geisina culbersonensis Crasquin sp. nov. N. Holotype, external view of a right valve, sample GM1 (MNHN.F.F63396). O. Paratype, external view of a right valve, sample GM1 (MNHN.F.F63397). P. External view of a left valve, sample GM2 (MNHN.F.F63398). – Q–R. Miltonella cf. shupei Sohn, 1950. Q. External view of a left valve, sample 4 (GM5) (MNHN.F.F63399). R. External view of a left valve, sample 4 (GM5) (MNHN.F.F63400). Scale bars: 100 µm.