Panisaspis topscityensis, Neo & Adrain, 2011

Neo, Usa & Adrain, Jonathan M., 2011, 2969, Zootaxa 2969, pp. 1-68 : 15-17

Panisaspis topscityensis n. sp.

Figs. 22–24

? 1973 Hintzeia sp. zone G2; Demeter, pl. 3, fig. 15. 2009 Pliomeridae gen. nov. sp. nov. 2; Adrain et al., p. 563, fig. 13BB.

Material. Holotype, pygidium, SUI 115253 , and assigned specimens SUI 125731–125744 from Section G 210.2 m, Fillmore Formation (Tulean; Protopliomerella contracta Zone ), southern Confusion Range , Ibex area, Millard County, western Utah, USA.

Etymology. After Top's City Cafe in Delta, Utah, where we have eaten many breakfasts during Ibex fieldwork.

Diagnosis. Hypostome with wide and very long border; with two pairs of elongate small spines at posterolateral corners; posterior border medially pointed; librigenal border very curvy (convex outward), with large triangle of doublure visible externally over inner edge of posterior projection; large pygidia nearly effaced except for thick rim of granules near furrows and edges of spines; third pair of pygidial spines longer than fourth pair by (approximately) "inseam" measurement of fourth pair.

Description. Cranidium short, narrow anteriorly and broad posteriorly, highly vaulted by strongly downturned fixigenae; anterior border moderately short, fairly wide, inflated and anteriorly curved such that doublure is expressed as anterior face and only a rim ventrally, strongly anteriorly arched with narrow lateral sections in front of palpebro-ocular ridges, with dense granulose sculpture; anterior border furrow short, slightly longer medially, fairly shallow except along lateral segments, with deep apodemal pits near S3; palpebro-ocular ridges long, dorsolaterally raised, with steeply sloped anterior face, finely and densely granulose, with small pits on anterior face distinguishing very narrow granulose ridge (anterior view); palpebro-ocular furrow not well known, narrow, deep, incised; inner fixigenae long, narrow, finely granulose with densely spaced small pits except along axial and posterior border furrows; outer fixigenae not well known, with sculpture like inner fixigenae, strongly downturned; posterior border furrow short, deep, incised, transverse along most of posterior border, but strongly anteriorly curved at genal angle; posterior border short adaxially, lengthened laterally to maximum at genal angle, then abruptly anterolaterally tapered to a point, with dense tiny granules and small spine at genal angle, doublure short adaxially, expanded laterally to maximum just adaxial from genal angle, with broad, shallow scoop as facial suture cuts genal angle; axial furrows subparallel, narrow, wider at lateral glabellar furrows and along LO, deep, convergent with all other cranidial furrows except palpebro-ocular; LO moderately long medially, gently tapered laterally, slightly narrower than maximum glabellar width, with sculpture of granules overlain by small tubercles, doublure reaches about halfway to SO, slightly tapered laterally, smooth; SO somewhat long and shallow medially, short, deep, and incised laterally, particularly in apodemal pits; glabella sub-ovoid, with maximum width across L2 104.7% sagittal length, shallowly inflated, with distinct lateral lobes, and with very dense sculpture of small granules; L1 smallest, shorter and slightly narrower but nearly same size as L2 and L3, sub-ovoid; L2 and L3 similar, short, sub-rectangular, about 1/3 total glabellar width; LF large, wedge shaped, long medially and strongly tapered laterally; lateral glabellar furrows all similar, short, deep, incised, about 30º above horizontal, with S3 slightly shallower, and S1 with elongated inner end.

Rostral plate unknown.

Hypostome long and wide, with width across wings 81.7% (78.2–85.2%) sagittal length; hypostomal suture broad, nearly flat medially, then gradually posteriorly sloped along wings, with small flat section along apodemal pits; anterior border extremely short medially, rapidly expanded laterally into tall, strongly dorsolaterally raised, large, approximately 30–60–90º triangular wings with very deep apodemal pits; anterior border furrow short, deep medially, effaced laterally with only slight connection to overlap of lateral and middle body furrows; middle body long, narrow, posteriorly tapered, with very large ovoid anterior lobe and short, small, U-shaped posterior lobe, strongly ventrally convex, with convexity highest even with lateral notch and gradually decreasing anteriorly and posteriorly, densely granulose, with larger granules anteriorly and with tiny granules toward and on posterior lobe, also with irregularly spaced small pits on anterior lobe; middle body furrow very narrow and deep anterolaterally, with anteriormost segment confluent with lateral furrows (then separated by anterolateral branch of posterior lobe of middle body), and with median segment strongly posteriorly curved and nearly effaced; lateral border furrows narrow, deeply incised, strongly anteriorly divergent, disconnected by posterior lobe of middle body; posterior bor- der furrow very shallow and indistinct; lateral border very narrow anteriorly at junction with wings, then strongly expanded posterolaterally, moderately downturned, with broad nubby angle at shoulders, two pairs of medium sized spines at posterolateral corners, and very dense granulose sculpture; posterior border long, wide, formed into very broad median point; doublure wide along lateral notch, narrower and shorter posteriorly, strongly upturned, with long lateral notch and small triangular posterior wings.

Librigena long and narrow, subtriangular, with width of field approximately 33.1% length along lateral border furrow and length of field 50.3% length of border; anterior branch of facial suture very short and subvertical along librigenal field, then long and subhorizontal along lateral border; posterior branch of suture long and moderately sloped along field, with small change in slope about midway to border, shorter (about half length) and slightly upturned along border; ocular surface poorly known, strongly raised above field with abrupt break in slope at base of eye; librigenal field of low convexity, long, narrow, subtriangular, densely granulose (moreso on smaller specimens), with many evenly spaced, irregularly shaped small pits; lateral border furrow moderately wide, slightly tapered posteriorly, deep, gently laterally bowed; lateral border long, with anterior projection of almost 1/3 total length and posterior projection slightly shorter, wide, almost width of librigenal field, with maximum width just before anterior projection, strongly inflated anteriorly, less so posteriorly, with outer margin gently convex over most of length, but flattened abruptly along outer half of anterior projection, and with very dense granulose sculpture; doublure wide, slightly over half total width of border, smooth, with inner side visible as small triangle above posterior tip of border in external view, does not extend along anterior projection.

Thorax unknown.

Pygidium of four segments each with long spines and terminal piece, strongly vaulted axially and pleurally, roughly triangular, with sagittal length of axis from articulating furrow 68.4% (66.1–70.1%) width across anterior pleural band; articulating half ring very short and wide, slightly longer medially; articulating furrow long, deep, slightly tapered laterally into apodemal pits; axis moderately long, wide anteriorly and strongly tapered, triangular, highly vaulted anteriorly with vaulting progressively decreased to almost none across terminal piece; first axial ring wide, about twice length of articulating half ring, slightly shorter medially on larger specimens, strongly independently inflated, with rounded lateral edges, and with small granules lining edges, subsequent rings slightly shorter and increasingly narrower, with fourth ring about half width of first; first inter-ring furrow long medially and tapered somewhat laterally, deep, second furrow also longer medially, subsequent furrows shorter; terminal piece about as long as last two rings, narrow, triangular, with granulose sculpture concentrated anteriorly, and with posterior point separated from pygidial margin by depression of posterior junction of axial furrows; axial furrows moderately narrow, deep, well impressed over all segments and along terminal piece; inner pleurae very narrow and increasingly so posteriorly, with steep fulcral angle (about 30º from vertical; Fig. 24.8), outer pleurae slightly wider, merged into short, granulose ventral wall; first segment only with anterior and posterior pleural bands, anterior band very short, slightly flared and anteriorly directed at tips; pleural furrow short, slightly expanded ventrolaterally, deep; posterior pleural bands strongly inflated, with rounded inner margin, merged into long, somewhat laterally flattened conical spines; spines strongly posteriorly directed, with fourth pair subparallel to convergent, moderately splayed, longest on third segment and shortest (about half length of third) on fourth, very droopy with slightly upturned tips, and with margins of pleurae and spines granulose and central areas effaced; interpleural furrows moderately long (first longest), strongly backturned, deep; pygidial doublure V-shaped or triangular, longest posteromedially and tapered anterolaterally ( Fig. 24.8), smooth.

Ontogeny. Cranidia are not known from enough specimens to discuss. Librigenal changes include elongation and anterior widening of the lateral border, development of the curve near the anterior projection, and refinement of the granulose sculpture; the field narrows and elongates, the pits increase in size, and the granules fade away. The hypostome increases in width overall, particularly along the posterior and lateral borders, the middle body also elongates, widens, and inflates more, the middle body granules are reduced except anteriorly, and the posterior bor- der develops the median point. Pygidial changes are striking and well represented. The pygidial spines spread out slightly, elongate relative to the sagittal pygidial length, develop a stronger taper, and become dorsally effaced; the fourth pair of spines increases in length and the third pair dramatically increases in length; the axis widens and inflates, while the rings shorten medially and the inter-ring furrows lengthen, and the small tubercles of small specimens shrink to granules; the axial furrows widen; and the interpleural furrows lengthen.

Discussion. Panisaspis topscityensis most closely resembles P. quattuor , although some aspects of their morphology are very different. Cranidia of P. topscityensis are not well preserved, but they clearly possess a longer and more inflated anterior border; a laterally convex glabella; a smaller L1 relative to the other lateral lobes; a tuberculate LO; a longer, wider genal angle with a larger spine; and they retain dense granulose sculpture on the glabella and fixigenae even at a large size. The best match for hypostomal comparison are those of Figs. 23.10 and 26.11. The hypostome of P. topscityensis is longer and wider; has larger wings; shallower middle body and lateral border furrows; larger and more evenly distributed tubercles on the anterior lobe of the middle body; larger pits on the anterior lobe; much larger posterolateral corner spines; and a longer, more medially pointed posterior border. Additionally, although exact size comparison is lacking, it seems that the anterior border is shorter and the posterolateral corner spines are longer at larger sizes in P. topscityensis . Librigenae (cf. Figs. 22.10; 26.12, 29.7 and alternate views) are highly similar, but those of P. topscityensis have a shorter librigenal field near the eye; slightly narrower field overall; wider and curvier lateral border; longer posterior projection of the border; and less downturned anterior projection of the border. No segments of P. topscityensis are known for comparison. Pygidia of the two species are also similar, but those of P. topscityensis are wider; with more splayed spines; longer spines compared to sagittal length; a slightly narrower axis; shorter axial rings; a shorter and narrower terminal piece with a posterior furrow and no indentations; longer third spine pair compared to fourth spine pair (at tips); longer fourth spine pair; and denser, coarser granulose sculpture, particularly on the axis. Comparison with Panisaspis rancherensis and P. loganensis was made in the discussion sections of those species.

Demeter (1973, pl. 3, fig. 15) illustrated a single cranidium from Mesa 1027' (≈ G 219.6 m) as " Hintzeia sp. zone G2". This specimen appears to belong to P. topscityensis , and may indicate an upward extension of its range.