Panisaspis quattuor ( Hintze, 1953 )

Neo, Usa & Adrain, Jonathan M., 2011, 2969, Zootaxa 2969, pp. 1-68 : 17-21

Panisaspis quattuor ( Hintze, 1953)

Figs. 25–32

1953 Protopliomerops ? quattuor Hintze , p. 209, pl. 21, figs. 9, 12–14 [only; pl. 21, fig. 10 = Ibexaspis n. sp.; pl. 21, fig. 11 = Ibexaspis brevis ( Young, 1973) ].

1973 Protopliomerops quattuor Hintze ; Demeter, p. 53, pl. 3, fig 6 (only; fig. 1 = Ibexaspis n. sp.).

? 1973 Protopliomerops aff. P. quattuor Hintze ; Demeter, p. 53, pl. 3, fig. 7 (only; fig. 2 = unknown pliomerid sp.).? 1973 Hintzeia cf. H. insolita ( Poulsen, 1927) ; Demeter, pl. 4, fig. 10 (only).

1985 Protopliomerops quattuor Hintze ; Jell, p. 74, 80.

1985 Ibexaspis quattuor (Hintze) ; Přibyl et al., p. 119.

1989 Protopliomerops ? quattuor Hintze ; Dean, p. 13.

2009 Pliomeridae gen. nov. quattuor ( Hintze, 1953) ; Adrain et al., pp. 559, 561, figs. 10U, Y, 11J, L.

Material. Assigned specimens SUI 115193, 115194, 115219, 115220, 125745–125815 from Section G 155.6 m, 162 T m, and 174.0 m, Fillmore Formation (Tulean; Psalikilopsis cuspidicauda Zone and Psalikilus typicum Zone ), southern Confusion Range, Ibex area, Millard County, western Utah, USA.

Diagnosis. Glabella and occipital node effaced on large cranidia; hypostome with two pairs of small but distinct spines at posterolateral corners; axial rings of thoracic segments effaced and pleurae exceedingly finely granulose; pygidium effaced dorsally except for thin rim of granules around furrows; third pair of pygidial spines only slightly longer than fourth when compared at tips.

Description. Cranidium short, narrow anteriorly and very broad posteriorly, somewhat triangular in outline, with sagittal length 51.1% (44.0–55.7%) maximum width measured across posterior border at genal angle, highly vaulted (tr.) abaxially, nearly flat (tr.) adaxially (anterior view); anterior border short, narrow but slightly wider than glabella, moderately anteriorly curved in course, with slight median point, moderately inflated and anteroventrally curved such that doublure is mainly expressed as anterior face of border (longer medially) and only a rim ventrally, with inverted-U-shaped cross-section, and with dense granulose sculpture dorsally (reduced anteriorly); anterior border furrow very short, deep, incised, anteriorly bowed medially, with narrow (tr.) anterolaterally directed lateral branches separating anterior border and palpebro-ocular ridges, and with deep apodemal pits at junction with axial furrows producing very large apodemes ventrally; palpebro-ocular ridges arcuate, much longer and wider anteriorly, strongly tapered posteriorly, strongly anteriorly downturned from maximum point of curvature roughly even with mid-L3, with line of small pits (shallow furrow in some specimens) extending slightly posterolaterally from junction of posterior border and glabellar furrows (anterior and oblique views; more prominent in larger specimens), and with fine granulose sculpture; palpebro-ocular furrows sigmoid in course, short and narrow, shallow at anteromedial and posterolateral tips, otherwise deeply incised; fixigenae wedge shaped, with inner fixigenae narrow and long, about 3/4 glabellar length, outer fixigenae short, wide, and steeply ventrolaterally sloped, fixigenae with dense sculpture of small pits and sparse granules, dorsally effaced near glabellar, palpebroocular, and posterior border furrows, but with granules lining furrow margins; posterior border furrow short adaxially, longer abaxially, tapered anterolaterally, deep, course horizontal adaxially and strongly anterolaterally curved abaxially; posterior border wide, short adaxially, flared abaxially and slightly posteriorly to maximum length at genal angle, then strongly tapered anteriorly, moderately inflated, with very small, nubby spine at genal angle and overall extremely fine and mostly effaced granulose sculpture; posterior border doublure short, slightly flared laterally and longest at genal angle, with cut by facial suture just anterolateral from genal angle, and with short, wide, articulating tongue near axial furrows set off by short, deep articulating furrow; axial furrows wide, narrower anteriorly and along LO, deep, gently laterally convex in course, confluent with SO, posterior and anterior border furrows; glabella long, thimble-shaped, with maximum width across L1 98.4% (87.8–109.8%) sagittal length, gently anteriorly tapered, slightly inflated (sag., tr.), sagittal profile (lateral view) moderately anteriorly sloped, with three pairs of well-defined lateral lobes, and with dense sculpture of fine granules; L2 and L3 large, rectangular, roughly equal in size, L1 slightly smaller and subtriangular in shape, each lobe roughly 1/3 total glabellar width, median lobe long, narrow, slightly tapered anteriorly, rectangular, approximately 1/3 glabellar width, frontal lobe large, subtrapezoidal, with small, circular, slightly raised and effaced areas near S3 on some larger specimens (e.g., Fig. 25.1); glabellar sulci short and deep, with S1 and S2 confluent with axial furrows, and S3 confluent on most specimens (see Fig. 28.1 for exception), S1 with slightly longer medial end, all sulci directed anterolaterally at 30–45º angles; SO moderately long, deep, shorter and deeper in smaller specimens, with very deep apodemal pits just adaxial from axial furrows, course transverse medially, slightly anterolaterally directed laterally; LO long, wide, rectangular, but with indents near anterolateral corners from SO apodemal pits, moderately inflated, with sculpture of partially effaced tiny granules; LO doublure moderately long, reaching halfway to 3/4 toward SO, smooth, with slightly raised lateral margins.

Rostral plate unknown.

Hypostome long, wide, with maximum width across anterior wings 83.3% (79.0–88.9%) sagittal length and width across shoulders slightly narrower on most specimens; hypostomal suture very wide, gently anteriorly bowed; anterior border wide, short medially, expanded laterally into large, sub-equilaterally triangular anterior wings, anterior border effaced; wings with deep wing process pits, and with very light granulose sculpture, heavier posteriorly; anterior border furrow moderately long and deep medially, shorter and shallower laterally toward merger with lateral border furrows; middle body long, moderately narrow, widest even with shoulders and strongly posteriorly tapered, anterior lobe large, ovoid, deeply ventrally inflated, with well-defined lateral limits set by moderately narrow, deep lateral branches of middle body furrow, median and posterior limit not well defined by short, very weakly impressed furrow, with dense sculpture of large granules or small tubercles and with scattered small pits near median furrow on most specimens, posterior lobe short, small and U-shaped, with narrow anterolateral arms defined by middle body and lateral border furrows, not well defined posteromedially by long, shallow posterior border furrow, lobe slightly ventrally inflated, with very fine granulose to effaced sculpture; lateral border furrows overlap with middle body furrow anteriorly, almost completely effaced over anterolateral branch of posterior middle body lobe, then moderately wide and deep, with strongly posteriorly convergent course along sides of posterior middle body; lateral border narrowest at lateral notch, strongly flared out to shoulders, and expanded posteriorly to posterolateral corners of hypostome but with lateral margins roughly parallel-sided, slightly ventrally downturned away from lateral border furrows, with dense granulose sculpture, and with very short, rounded triangular spine at shoulders, and small, nubby to short spines roughly even with posterior border furrow and at posterolateral corners; posterior border long, longer medially, equal in width to anterior border minus wings, with rounded posterior margin, effaced near posterior border furrow but mainly with dense granulose sculpture; lateral notch long, shallow, exposes deep doublure; posterior wing long and short, triangular (not well known due to breakage); lateral border doublure wide at notch, then tapered, and strongly dorsomedially raised, and posterior border doublure moderately short, slightly raised, with rounded anterior margin.

Librigena long and fairly wide, roughly triangular in shape, with width of field at midpoint of eye 34.8% (28.4–38.1%) length along lateral border furrow, and length of field 53.3% (49.7–57.2%) length of lateral border, and with long anterior and posterior projections of the lateral border; anterior branch of facial suture very narrow along field, nearly perpendicular to long, slightly ventromedially sloped branch along anterior lateral border projection; posterior branch of facial suture long, steeply obliquely sloped about 30º below horizontal to lateral border, with long slightly posterodorsally directed branch along border; ocular surface unknown; eye socle or semicircular area adjacent to ocular surface narrow and effaced, site of abrupt break in slope from eye to librigenal field; librigenal field triangular, narrow anteriorly, widest at posterior edge of eye, then rapidly posteriorly tapered to a point, gently laterally convex, with dense granulose sculpture and dense, irregularly shaped pits; lateral border furrow moderately wide, long, deep in most specimens (but see Fig. 29.4, 29.14), with gently posteriorly sloped curvature; lateral border wide, slightly tapered anteriorly and strongly tapered posteriorly, strongly inflated, with dense granulose sculpture; lateral border doublure about 3/4 as wide as border, absent along anterior projection of border, slightly tapered posteriorly, with triangular projection at posterior tip visible in external view.

Total number of thoracic segments unknown. Segments short, broad (varies with thoracic position), with broad axis 44.8% (38.9–52.5%) total pleural width excluding spines, highly vaulted axially and pleurally with posterior segments increasingly vaulted; articulating half ring short, slightly tapered laterally, wide, and sharply raised above articulating furrow, with tiny granules on posterior rim; furrow with very broadly U-shaped course, long, deep, slightly shorter and deeper anterolaterally, with broad and moderately deep apodemal pits at anterolateral limits; axial ring moderately long, about half length of articulating half ring plus furrow, slightly broader than half ring and very shallowly anterolaterally curved, moderately dorsally inflated, slightly overhanging axial furrows (e.g., Fig. 30.18), with tiny granules lining anterior rim and concentrated at anterolateral limits (anterior view, e.g., Fig. 30.4) but dorsal surface effaced; axial furrows fairly narrow, deep, strongly impressed over posterior pleural band, then anterolaterally triangularly flared into pleural furrow and slightly shallower over anterior pleural band, with nearly subparallel course posteriorly, then strongly anteromedially convergent from pleural furrow; ring doublure fairly long, slightly tapered laterally, effaced, with outer corners connected to posterior rim of posterior pleural band; pleural bands of equal width, but anterior band appears narrower due to pleural spine on posterior band, inner pleurae slightly narrower than outer pleurae, fulcral angle strongly downturned (gentler in anterior segments); anterior pleural band short, slightly longer laterally, with very short articulating ridge on anterior edge of inner pleurae set off by very short incised furrow (left pleura of Fig. 30.1, Fig. 30.22), with ridge and furrow continuous ventrolatererally but somewhat effaced ( Fig. 30.11, 30.19), ending in very small anteriorly facing hook-like structure made from anteriormost edge of short, strongly upturned doublure (best viewed anteriorly), effaced; pleural furrow short and deep, slightly longer ventrolaterally and slightly shorter and shallower near axis; with straight to slightly posterolaterally curved course; posterior pleural band roughly twice as long as anterior band, moderately dorsally inflated, effaced dorsally, but with dense sculpture of tiny granules on other surfaces, with ventrolateral tips ending in very large, slightly laterally flattened, distally tapered, and slightly anteriorly curved pleural spine.

Pygidium highly vaulted axially and pleurally, made of four segments each with long spine, and medium sized triangular terminal piece, with sagittal length from articulating furrow to tip of terminal piece 67.0% (61.3–73.0%) maximum width across tips of anterior pleural band; articulating half ring short, laterally tapered, wide, slightly inflated, with tiny granules lining posterior margin; articulating furrow long and deep, tapered anterolaterally into very deep apodemal pits; axis of four axial rings and terminal piece moderately long (compared to length of pygidium including spines), broad anteriorly, strongly tapered posteriorly to very narrowly exposed tip of terminal piece, highly vaulted anteriorly with convexity decreasing posteriorly; axial rings subrectangular with rounded lateral margins, progressively narrower and slightly shorter, each strongly independently inflated, dorsally effaced, with fine granules rimming anterior and posterior margins; terminal piece triangular, subequilateral with length slightly longer than width, rapidly tapered to posterior point, moderately inflated, dorsally effaced, with granules lining all margins, and with somewhat triangular ( Fig. 31.24) to irregularly shaped ( Fig. 27.1) depression linking final interring furrow and anterior margin; axial furrows moderately wide, narrower posteriorly and narrowest between fourth axial ring and terminal piece, flared anteriorly and posteriorly at junctions with interpleural furrows, deepest midway along axis, slightly shallower anteriorly, and fairly shallow along posterior taper of terminal piece; pygidial pleurae with very narrow inner pleurae (narrower on posterior segments), strongly downturned fulcrum, and with outer pleurae roughly twice as wide as inner; anterior pleural band only present on first pygidial segment, short, slightly flared at distal tips into small articulating hook structure, equally broad as posterior band, with granules lining posterior margin; pleural furrow short, deep, incised; posterior pleural band of first pygidial segment double to triple length of anterior band, bands of successive segments slightly shorter, strongly independently inflated, increasingly posteriorly directed, with fourth posterior pleural bands posteriorly convergent, dorsally effaced, with fine granules lining anterior, posterior, and median margins; each segment with very large, long pleural spine much like those of thorax (tapered to point, slightly laterally compressed, more bladelike than perfectly conical, first three spines roughly equal in length from axial furrows to tip, but spines of fourth segment distinctly shorter than those of third, all dorsally effaced but with dense fine granulose sculpture on all other surfaces; interpleural furrows moderately long, slightly tapered laterally and flared posteriorly (posterior view), deep, strongly and increasingly backturned like pleurae; inner pygidial doublure very broadly triangular in anterior view ( Figs. 27.9, 32.5), rounded medially and strongly tapered anterolaterally, outer doublure (ventral views) shelf-like, moderately inflated, and densely granulose, with broad, moderately shallow furrow running along and between bases of spines, and with triangular median inflection in posterior view.

Ontogeny. Panisaspis quattuor is the best known species of the genus, with ample material demonstrating some of its ontogenetic changes. The cranidium overall becomes wider and shorter; the coarse granulose sculpture is increasingly effaced, and the pits enlarged; the anterior border lengthens and inflates; the axial furrows widen significantly, and all other cranidial furrows lengthen; the glabella shortens, widens posteriorly, and tapers anteriorly; the occipital node almost disappears; and the small genal spine is reduced to a slightly pointed genal angle. The hypostome widens, particularly across the shoulders and posteriorly; the middle body widens anteriorly, inflates, and the granules fade away posteriorly; the lateral border increases in width, and the spines at the shoulder and posterolateral corners are reduced; and the posterior border lengthens. Librigenal changes include the widening of the field; effacement of granules on the field; enlargement and increasingly irregular shape of the pits; widening of the lateral border furrow; widening of the lateral border, particularly anteriorly; elongation of the anterior and posterior projections; and slight fining of the granulose sculpture. The thoracic segments are too large and too close in size to permit observation of ontogenetic changes. The pygidium becomes slightly more elongate and the axis narrows slightly relative to the maximum width; the terminal axial piece elongates and narrows posteriorly into a sharper taper; the pygidial spines elongate; the third spines become longer relative to the fourth spines (cf. Fig. 31.1 and 31.3); and the granulose sculpture coarsens on the lateral and ventral faces of the spines (cf. Fig. 31.5 and 31.6 with 31.8).

Discussion. Hintze (1953, pl. 21, figs. 9–14) figured two cranidia from Section H 191.7 m ( Hintze's [1953] H-20) in the Strigigenalis plicolabeona Zone with a cranidium, a librigena, and two tails from Section G 174.0 m ( Hintze's [1953] G-14) in the Psalikilus typicum Zone as Protopliomerops ? quattuor n. sp.. The larger cranidium ( Hintze, 1953, pl. 21, fig. 11a, 11b) from H 191.7 m is that of Ibexaspis brevis ( Young, 1973) . The smaller cranidium ( Hintze, 1953, pl. 21, fig. 10) represents a new species of Ibexaspis Přibyl and Vaněk in Přibyl et al., 1985. The remaining four sclerites ( Hintze, 1953, pl. 21, figs. 9, 12, 13, 14) represent Panisaspis quattuor ( Hintze, 1953) . The cranidium ( Hintze, 1953, pl. 21, fig. 9) is small (cf. Fig. 25.16), possibly juvenile, and therefore much more granulose than most of the figured cranidia herein. Additionally, the small size and orientation of Hintze's photograph make the cranidium resemble new species of Ibexaspis from the P. typicum Zone , but no species of Ibexaspis is present at G 174.0 m ( Adrain et al. 2009 faunal list, p. 561). Young (1973) recognized that Hintze's association was incorrect, and named Protopliomerops quattuor brevis (now Ibexaspis brevis ) for one of the species from H 191.7 m; the other is new and awaits formal naming. Ibexaspis will be treated in a forthcoming paper.

Demeter (1973) figured three pygidia (pl. 3, figs. 6, 7, 10 only) from sections G and Mesa which are assignable to P. quattuor . That of pl. 3, fig. 6 was correctly identified, but the associated cranidium (pl. 3, fig. 1) belongs to a species of Ibexaspis . Demeter assigned the pygidium of pl. 3, fig. 7 to Protopliomerops aff. P. quattuor , but the associated pygidium of pl. 3, fig. 2 has five segments and clearly is not conspecific. The pygidium of pl. 3, fig. 10 was incorrectly assigned to Hintzeia celsaora and associated with four other pygidia and a cranidium, some of which belong to H. celsaora , but some of which represent a new species of Protopliomerella Harrington, 1957 .

Panisaspis quattuor is compared to P. topscityensis and P. rancherensis in the discussion sections of those species. It is compared to P. loganensis through differential description of that species.