Nevadia saupeae, Gapp, Wesley, Lieberman, Bruce S., Pope, Michael C. & Dilliard, Kelly A., 2011

Gapp, Wesley, Lieberman, Bruce S., Pope, Michael C. & Dilliard, Kelly A., 2011, New olenelline trilobites from the Northwest Territories, Canada, and the phylogenetic placement of Judomia absita Fritz, 1973, Zootaxa 2918, pp. 15-28 : 22-23

Nevadia saupeae n. sp.

(Fig. 6.1, 6.2, 6.4)

Type material. Holotype KUMIP 320711 and paratype PWNHC-2009.20.21 from Nevadella zone, Early Cambrian, Sekwi Formation, Mackenzie Mountains, Northwest Territories, Canada (Sections 2 and 14 in float). There are a total of 2 specimens.

Etymology. Named in honor of Erin Saupe, University of Kansas, for her assistance with laboratory techniques that facilitated the completion of this research.

Diagnosis. Laterally, anterior cephalic border width, when measured perpendicularly to a line tangent to the margin of the cephalon, is equal to length (sag.) of LO; length (exsag.) of genal spines less than length (sag.) of LO; extraocular area very broad (tr.).

Description. Cephalic length (sag.) 40–50 percent of width (tr.). Anterior cephalic border with width (measured perpendicular to a tangent to the margin) at the midpoint between anteriormost point of the border and inner spine angle equal to length (sag.) of LO. LA is about 35–45 percent length (sag.) of glabella; frontal lobe does not contact anterior border furrow; plectrum is not visible; lateral margins of LA are adaxial to lateral margins of LO; lateral margins of LA are convergent anteriorly; ocular lobes contact the frontal lobe at the posterior part of frontal lobe; anterior abaxial margins of L3 are formed by axial furrows, abaxial margins of L3 are straight; S3 straight, not conjoined medially; S2 straight, conjoined medially; L2 and L3 do not merge abaxially on internal mould but do on external mould; SO and S1 are straight, contact axial furrows, medial edges declined posteriorly, conjoined medially; width (tr.) of glabella opposite margins of L1 is constricted slightly relative to width at lateral margins of LO; posterior edges of ocular lobes are opposite medial margin of L1; posterior margin of LO convex posteriorly; genal spines of length (exsag.) approximately 1–1.5 times length (sag.) of LO, sweeping posterolaterally at roughly 40 degree angle relative to sagittal line; inner spine angle is opposite first thoracic segment; extraocular area opposite L1 is broad, width (tr.) approximately two times the width (tr.) of glabella at L1. Hypostome of elongate subrectangular shape, width (tr.) at midlength about two-thirds length (sag.), lateral margins are subparallel with each other; middle body ovate in outline, broadest near midlength, anterior margin is convex posteriorly, convexity (tr.) of middle body weak; maculae not visible. A partial rostral plate that tapers laterally and mirrors the anterior bor- der, plus five partially preserved thoracic segments that also taper laterally are visible in Figure 6.1.

Discussion. This species differs from N. weeksi and N. fritzi due to its lack of a plectrum and possession of very short (exsag.) genal spines; it differs from N. fritzi and N. ovalis by having the posterior border furrow approximately parallel to a transverse line; finally, it has a relatively wide (tr.) cephalon and extraocular area. Fritz (1973) figured early ontogenetic stages of cephala that he referred to Nevadia ? sp. but it was not possible to determine if these were conspecific with N. saupeae .