Panisaspis deltaensis, Neo & Adrain, 2011

Neo, Usa & Adrain, Jonathan M., 2011, 2969, Zootaxa 2969, pp. 1-68 : 11-13

Panisaspis deltaensis n. sp.

Figs. 17–19

2009 Pliomeridae gen. nov. sp. nov 4; Adrain et al., p. 567, fig. 15AA, GG.

Material. Holotype, pygidium, SUI 125706 , from Section H 127.1 m, and assigned specimens SUI 115289 , 115290 , 125696–125701 , 125707–125713 , from section H 93.4 m and 127.1 m, Fillmore Formation (Tulean; Heckethornia bowiei Zone ), southern Confusion Range , Ibex area, Millard County, western Utah, USA.

Etymology. From the town of Delta, Utah.

Diagnosis. Base of genal spine very broad; terminal piece large, but narrower and more elongate than in other species; third pygidial spine very long and stout compared to other spines; third pygidial spine recurved medially at tips; fourth spine very short.

Description. Cranidium short, narrow anteriorly and wide posteriorly, with sagittal length 47.1% width across genal angle, strongly vaulted; anterior border strongly anteriorly bowed, somewhat long and narrow, highly inflated, granulose; anterior border furrow very short, slightly longer medially, deep, incised, with narrow lateral branches anterior from palpebro-ocular ridges; glabella nearly equally long as wide, with maximum width across S2 99.8% (92.0–105.5%) sagittal length, moderately vaulted, densely granulose, with distinct lateral lobes and furrows; L1 about 25% smaller than L2 and L3, ovoid, L2 and L3 similar, sub-rectangular, LF large, wide, long, wedge-shaped; S1–S3 all short, deep, incised, posteromedially directed at about 30º above horizontal, S1 with slightly lengthened and deepened inner end; axial furrows narrow, deep, gently laterally bowed, convergent with other cranidial furrows; SO fairly short, moderately deep medially, very deep laterally in apodemal pits; LO slightly narrower than glabella across L1, long medially and slightly tapered laterally, with very slightly anterolaterally curved ends, granulose, with small median tubercle; posterior border furrow short, deep, incised, with posterior course sub-transverse, then gentle 90º curve at genal angle; posterior border short near axial furrows, flared outward to maximum length and width at genal angle, then strongly anteriorly tapered, with dense sculpture of tiny granules and moderately long, very thick, gradually tapered and blunt genal spine projecting at just past parallel; posterior fixigenae short (about half glabellar length), wide, subrectangular, interocular fixigenae short, narrow, subtriangular, fixigenae with very tiny dense granules and densely spaced small pits except along edges of axial and posterior border furrows; palpebro-ocular furrow sigmoidal, narrow, deeply incised over most of course but totally effaced near glabella; palpebo-ocular ridge not well known, extends from S3 to just short of S1, strongly angled dorsolaterally from cranidium, granulose.

Rostral plate unknown.

Hypostome long and narrow; anterior border not well known, short, flared laterally into small, approximately equilaterally triangular wings with small, deep wing process pits; anterior border furrow moderately anteriorly bowed, very short, shallow, and separated from lateral border furrow (where confluent with middle body furrow) by short effaced section; middle body ellipsoid, long, narrow, with maximum width even with lateral notch, posteriorly tapered, strongly ventrally convex anteriorly, decreasing posteriorly, with ill-defined lobes (anterior long and ovoid; posterior about 1/3 length of anterior and U-shaped, with lateral sections interrupting meeting of posterior border and lateral border furrows), and with dense granules slightly coarser than those of the borders concentrated anteriorly on anterior lobe; middle body furrow narrow, deep, strongly impressed laterally where overlapped with lateral border furrows, posteriorly convergent, almost totally effaced in curved medial section; lateral border narrowest at lateral notch, expanded posterolaterally to maximum at posterolateral corners, moderately downturned, with dense granulose sculpture and rounded angles at shoulders, posterolateral corners, and slightly posteromedially from corners; posterior border furrow shallow, moderately long, somewhat indistinct ventrally (better visible in Fig. 17.21), highly posteriorly curved; posterior border about as long as widest point of lateral border, somewhat downturned, with sculpture like that of lateral border; lateral notch long and shallow, with tall, smooth doublure; other hypostomal doublure not well known.

Librigena roughly triangular in outline, wide, moderately long, with small ellipsoid eye; anterior branch of facial suture short and very steep along field, almost flat and about equal in length along anterior projection of lateral border; posterior branch of facial suture long and posteriorly sloped at about 45º along field, then gently upturned along short segment of border; librigenal field fairly short and long, with width at midpoint of eye 43.3% (43.2, 43.3%) length along lateral border furrow, gently convex, with steep break in slope from ocular surface to field, and with very dense sculpture of tiny granules and small, irregularly shaped pits; lateral border furrow very narrow, deep, incised; lateral border long, wide, widest slightly behind anterior edge of field, shallowly curved, highly inflated, with dense granulose sculpture; border doublure wide, reaching about 2/3 to furrow, with curved margin, smooth, slightly projected above posterior end of border in triangular shape.

Thorax unknown.

Pygidium shorter than broad (axial length from articulating furrow 62.7% (61.5–63.7%) width across anterior pleural band), roughly subtriangular in shape, strongly vaulted axially and moderately vaulted pleurally, made of four segments, each with large spine, and large triangular terminal piece; articulating half ring very short and broad; articulating furrow long, deep, deepest in lateral apodemal pits; axis broad anteriorly, strongly tapered posteriorly to very narrow tip of terminal piece, strongly convex anteriorly decreasing to nearly flat terminal piece, with strongly independently inflated axial rings, rings short medially, slightly expanded laterally, densely granulose, with width decreasing posteriorly such that fourth ring is a little more than half width of first; inter-ring furrows long medially, abruptly tapered laterally to short slits over apodemal pits, deep; axial furrows moderately narrow and shallow, not well impressed over fourth segment, then well impressed along terminal piece, strongly posteriorly convergent but slightly posteromedially directed over fourth segment; terminal piece triangular, longer than wide, strongly posteriorly tapered, with pair of short indentations leading from last ring furrow, and with narrow but exposed posterior point; pleurae narrow, with inner pleurae narrower than outer, with moderately steep fulcral angle (anterior view) and outer pleurae merged ventrally into short, narrow wall structure; only first segment with anterior and posterior pleural bands, anterior band short and wide, gently backturned; pleural furrow short, very slightly ventrolaterally expanded, deep, incised; posterior pleural bands long, slightly expanded laterally into base of spine, highly inflated, granulose, with spines projecting ventro-posterolaterally from tips; spines thick, rapidly tapered, conical, with third pair very thick and long (about twice saggital length of pygidium), and gently upturned toward tips, and with short fourth pair; interpleural furrows long, moderately deep, increasingly posteriorly directed, with third furrows subparallel; doublure triangular, longest posteromedially and tapered anteriorly (anterior view), smooth, connected to short, externally granulose wall made of outer pleurae.

Ontogeny. Cranidial material of P. deltaensis is not well represented, but it is possible to see that the glabella becomes relatively wider and more convexly sided through growth, and the cranidial furrows become longer or wider and deeper. Hypostomes, librigenae, and thoracic segments are not sufficiently known for discussion. Pygidia of P. deltaensis slightly increase in width; all furrows lengthen or widen and deepen; the third spine pair becomes much wider and more widely splayed; and the terminal piece indentations become more prominent.

Discussion. Panisaspis deltaensis is compared with P. millardensis , P. sevierensis , and P. rancherensis in the discussion sections of those species. One cranidium ( Fig. 17.2) lacks the left L1.