Pseudoolenoides pogonipensis Adrain & Karim 2012, n. sp.

• Main Authors: Adrain, Jonathan M., Karim, Talia S.
• Format: Text
• Language: unknown
• Published: Zenodo 2012
• Subjects: Biodiversity; Taxonomy; Animalia; Arthropoda; Trilobita; Proetida; Bathyuridae; Pseudoolenoides; Pseudoolenoides pogonipensis; Greenland; Talia
• Online Access: https://dx.doi.org/10.5281/zenodo.5256916; https://zenodo.org/record/5256916

Pseudoolenoides pogonipensis n. sp. Plate 9, figs 1–5?, 6–19, Plate 10 1996 Pseudoolenoides aspinosus Fortey and Droser, p. 87, fig. 12.2, 12.4, 12.6 (only; fig. 12.1, 12.3, 12.5, 12.7 Pseudoolenoides aspinosus ). 1999 Acidiphorus ? lineotuberculatus Fortey and Droser, p. 189, fig. 4.20 (only; fig. 4.14–4.19 = Acidiphorus lineotuberculatus ). Material. Holotype, pygidium, SUI 130116 (Pl. 10, figs 10–12, 15, 16), and assigned specimens SUI 130116– 130119, 30021–130025, 130035–130037, 132146, from Section K-South 1.5 T m, Kanosh Formation (Dapingian; Pseudoolenoides dilectus Zone), southern Confusion Range, Ibex area, Millard County, western Utah, USA. Tentatively assigned specimens USNM 481342, 481343, and 495718, from 38 m above Hesperonomiella minor bed ("K"), Juab Formation (Dapingian; Psephosthenaspis glabrior Zone), Section J, southern Confusion Range, Ibex area, Millard County, western Utah, USA. Etymology. From the Pogonip Group. Diagnosis. Cranidium with nearly straight-sided glabella with relatively small area; librigena with strongly posteriorly lobate posterior margin of posterior border and strong accessory furrow on border near margin; hypostome with large subtriangular spine at shoulder and broad shelf posteriorly; pygidium broad, with dorsal sculpture dominated by raised lines; pygidial border furrow weakly impressed; posteromedian spine robust and apparently long. Description. Cranidium moderately vaulted; sculpture of raised anastomosing lines covers fixigena and LO; sculpture of prominent tubercles present on glabella and LO; anterior border with sculpture of fine raised lines arranged subparallel to margin; anterior border about half as long (sag.) as LO (sag.), abaxially tapered, anterior margin describing gently curved arc with slight peak medially, in anterior view dorsal margin slightly ventrally bowed and ventral margin broadly "U"-shaped, in lateral view border forms a strongly upwardly flexed sinuous shelf; anterior border furrow is long, dorsally concave, deep along entire course, slightly deeper and slit-like distally; frontal areas weakly dorsally inflated, strongly sloped downward from interocular fixigena, with sculpture of prominent, relatively widely spaced anastomosing lines; interocular fixigena held at very slight angle above horizontal plane, with almost no dorsal inflation, sloping slightly toward glabella, sculpture of anastomosing lines continues from frontal area, but lines are less prominent and more closely spaced; palpebral lobes not preserved; posterior fixigena incomplete, but with inflation similar to that of frontal area, sloped downward toward posterior border furrow; posterior border incomplete, but appears to be dorsally inflated (Pl. 9, fig. 10), set off adaxially by shallow border furrow, sculpture of very fine and closely spaced anastomosing line present on adaxial portion; glabella with maximum width opposite Ύ 79.9% sagittal length excluding LO; glabella bullet-shaped in dorsal view, sagittal length (excluding LO) 64.2% that of cranidium, moderately strongly vaulted, with apex sitting high above maximum height of fixigena in anterior view; lateral profile moderately curved, with anterior portion strongly downturned from horizontal plane; axial furrows faint and slightly laterally bowed around LO, width across posterior contact of furrows with posterior margin 43.5% cranidial sagittal length; axial furrows confluent with SO, forming deeper pit at intersection; axial furrows deepest opposite inferred anterior margin of palpebral lobe, slightly shallower posteriorly, of nearly equal width along entire course, slightly sinuous, running without obvious distinction into preglabellar furrow; preglabellar furrow and anterior border furrows confluent medially; fossula very faintly expressed dorsally as small swelling situated adjacent to axial furrow opposite S3; S1 very faintly impressed, directed posteromedially, in contact with axial furrows; S2 and S3 expressed dorsally as very small areas lacking sculpture; L1 defined partially by S1, with very weak independent inflation; prominent large tubercles present posteromedially, giving way to progressively finer tubercles on anterior portion of glabella, tubercles absent on small strip situated in middle of glabella, tubercles absent on lateral margins of glabella; background sculpture of fine, raised anastomosing lines present on anterior portion and lateral margins of glabella; LO long, sagittal length 16.2% that of cranidium, semi-lunate, longer sagittally than exsagittally, posterior margin strongly posteriorly bowed with median portion nearly transverse, anterior margin nearly transverse, sculpture of scattered prominent tubercles similar to those on glabella, very faint background sculpture of anastomosing lines continues from glabella onto LO; SO deep and very broad (sag. and exsag.), distal tips slightly shorter (exsag.), anterior and posterior edges with sharp contact with rear of main glabella and anterior edge of LO respectively, nearly transverse; doublure underlying LO broken, but with sculpture of fine, closely spaced raised lines set transversely. Librigenal measurements were made on specimens of Pl. 9, figs 9, 11. Main body of librigena (excluding anterior projection and genal spine) with maximum width behind eye 38.6% (33.2–44.1%) exsagittal length; anterior section of facial suture nearly transverse opposite field, slightly curved across lateral border; posterior section of facial suture extremely short, strongly sinuous across posterior border; visual surface not preserved on any recovered specimens, but long, apparently occupying large portion of length (exsag.) of genal field, bounded at base by narrow and shallow circumocular furrow (Pl. 9, figs 6, 9); field with prominent sculpture of fine raised lines arranged a scrobiculate pattern; triangular band of small tubercles present on field below visual surface, tubercles not prominent, band broadest anteriorly, spanning entire width of field, narrows posteriorly; lateral border furrow narrow and deep, does not meet posterior border furrow; posterior border furrow similar to lateral border furrow, ending in deep pit at base of genal spine; lateral border broad, with lateral margin gently flexed upward, border flattened and moderately inflated, with sculpture of fine raised lines running subparallel to margin; posterior border with sculpture of raised lines oriented in anastomosing pattern adjacent to border furrow, sculpture is rearranged into a series of lines running parallel to external margin toward margin, prominent flange present on posterior border from base of genal spine toward posterior facial suture, does not intersect posterior facial suture, flange less than half as wide as posterior border, flange separated from border by shallow, but distinct accessory furrow; sculpture from lateral and posterior borders continuous across lateral and posterior border furrows onto genal field (Pl. 9, fig. 9); genal spine apparently long (Pl. 9, fig. 11), but incompletely preserved on an recovered specimens, curved, inflation similar to that of lateral border, with sculpture of fine raised lines running down length of spine on all aspects, arranged in a "V"-shaped pattern with apex of "V" along external lateral margin of spine; area in front of base of genal spine (confluence of lateral and posterior borders) flat, merges smoothly into genal field, sculpture of fine raised lines continues from base of spine onto genal field, but becomes arranged in a more anastomosing pattern; anterior projection long, with subparallel raised lines continuous from lateral border; doublure strongly upturned anteriorly beneath anterior part of lateral border and anterior projection, remains strongly upturned, but broader beneath posterior border; doublure with sculpture of faint, fine raised lines set subparallel to external margin, sculpture more effaced medially on widest portion of doublure just behind base of genal spine; inner margin of doublure describes smooth continuous arc, with curve strongest posteriorly opposite intersection of lateral and posterior borders; small Panderian notch (Pl. 9, fig. 15) developed along adaxial end of doublure beneath posterior border. Hypostome with maximum width (excluding anterior wings) across shoulder 92.5% sagittal length; ventral surface, including furrows, covered with sculpture of raised lines, arranged in anastomosing pattern on middle body, aligned subparallel with margins on borders, sculpture subdued on anterior wing; middle body with maximum width 49.9% maximum length of middle body, maximum width of anterior lobe 116.9% maximum width of posterior lobe; sculpture on middle body composed of densely spaced anastomosing raised lines; anterior margin describing broadly curved arc, medial portion opposite hypostomal suture turned upward at nearly 90° angle to form short anterior-facing rim, with sculpture of subparallel raised lines continuing from anterior lobe of middle body and arranged in a way that outlines the lateral and anterior margins of the anterior lobe of the middle body; anterior wing extended dorsolaterally, lacking sculpture of raised lines on anterior portion, posterior portion with sculpture of subdued raised lines; lateral notch also smooth (Pl. 10, fig. 5); shoulder developed into a prominent, pointed, and posterolaterally and ventrally directed spine (Pl. 10, fig. 5), anterior margin describing convex outward arc, posterior margin describing concave outward arc, sculpture of prominent raised lines running parallel to margin of spine on ventral surface and cutting across spine on dorsal surface; lateral and posterior borders weakly inflated, dorsoventrally flattened, enclosing middle body, with sculpture of closely spaced raised lines oriented subparallel to hypostomal margin; lateral border furrow separated into two portions, both are deep, slit like, directed posteromedially, with the posterior portion nearly effaced opposite posterolateral corner of middle body, not confluent with posterior border furrow; posterior border furrow shallow, deepest abaxially, nearly effaced medially, describing broadly curved arc around posterior margin of middle body; intersection of lateral and posterior borders forming rounded corner and meeting at nearly 90º angle; posterior border long (sag. and exsag.), with sagittal length 16.3% length of hypostome, posterior margin describing very gently curved arc, ventrally flexed, but less so than shoulder spine; middle furrow set at about two thirds distance posteriorly on middle body, expressed as pair of short, deep, posteromedially directed furrows, which do not meet medially, separated from posterior portion of lateral border furrow by narrow strip of inflated middle body, confluent with anterior portion of lateral border furrow; macula small; middle body with strong ventral inflation, strongly pinched at middle furrow; doublure present behind shoulder spines, posterior portion of lateral border, and posterior border, broadest exsagittally behind posterior border, narrows slightly medially; entire doublure with sculpture of several fine raised lines similar to that on posterior border. Rostral plate and thorax unknown. Pygidial measurements were made on specimens of Plate 10 and doubled from the sagittal line if specimen is incomplete. Pygidium with maximum width across anterior margin of third axial segment 244.5% (242.3–243.4%) sagittal length of axis (excluding articulating half ring); axis of three clearly defined segments and fourth poorly expressed (although clearly expressed ventrally) segment fused with terminal piece, maximum axial width across first ring 30.0% (29.9–30.0%) maximum pygidial width; width across third segment 78.7% (78.7–78.7%) width across first segment; length of axis excluding articulating half ring slightly shorter than sagittal length of pygidium; articulating half ring incomplete, but appears short (sag.; exsag.), maximum width slightly less than that of first axial segment; articulating furrow well defined (sag. and exsag.), transverse, slightly deeper abaxially; first ring furrow well defined (sag. and exsag.), transverse, deepest of ring furrows, slightly shallower medially, deep and slit-like abaxially; second and third ring furrows similarly transverse, progressively shorter and more effaced than first ring furrow, with fourth furrow completely effaced dorsally; first axial ring of nearly equal length sagittally and exsagittally, length (sag.) 13.4% (12.6–14.1%) axial length (sag.), with sculpture of raised posterolaterally directed lines present along anterior and lateral portions, sculpture of very faint medium sized tubercles present medially forming a semicircle of tubercles emanating from the posterior margin and in a row along posterior margin; second and third rings progressively smaller and with essentially the same morphology, except that tubercles are completely absent along posterior margin of third ring with only a few present medially in a smaller semicircle; poorly expressed fourth segment fused with terminal piece, clearly visible in ventral view (Pl. 10, figs 6, 15) by expression of fourth inter-ring furrow; axis terminated by anteriorly broad terminal piece that tapers posteriorly, sculpture of raised lines continues from axial rings onto terminal piece, becoming more granular on medial portion of terminal piece; axis distinctly terminated in dorsal view by narrow, shallow furrow outlining terminal piece, in lateral view posterior margin of axis forms very slight change of slope before emergence of posterior median spine; articulating facet small, triangular with short, spike-like projection developed at anterolateral corner (Pl. 10, fig. 3), short ventrally directed spine-like point developed at lateral corner (Pl. 10, figs 16, 17), covered with sculpture of fine raised lines oriented subparallel to anterior margin; first segment with anterior margin slightly anteriorly bowed to border furrow, directed posterolaterally at about 19º angle; anterior margin of first pleural band set off from margin by shallow, posterolaterally directed accessory furrow; anterior margin of first pleural band developed into anterolaterally directed ridge, narrow strip of pleurae along either side of first pleural furrow smooth; first pleural furrow of similar length sagittally and exsagittally, slightly deeper abaxially, nearly effaced adaxially at intersection with axial furrow (Pl. 10, fig. 11), distal tip terminated just past lateral border furrow; subsequent pleural furrows of similar length and depth sagittally and exsagittally, shallower than deepest portion of first pleural furrow, meet axial furrow, terminate at lateral border furrow, progressively more posterolaterally directed than first pleural furrow with fourth furrow nearly parallel to sagittal axis; first interpleural furrow expressed as very shallow depression at intersection of pleurae with border furrow, subsequent interpleural furrows not expressed; morphology of subsequent segments generally similar to segment one, but directed more posterolaterally and without strong inflation of anterior margin; pleural bands terminated by weakly inflated, flattened border, with sculpture of densely spaced raised lines oriented roughly parallel to pygidial margin, border broadest anteriorly, tapers posteriorly; border slightly bowed outward opposite first and second pleural bands, bowed very slightly inward opposite terminal piece and base of posterior spine; border set off from pleurae by very shallow furrow, almost no change in slope and inflation between pleurae and border, in posterior view border is medially arched upward below posterior spine (Pl. 10, figs 10, 14); posterior median spine apparently long (Pl. 10, fig. 11), but full length unknown, anteriorly broad (tr.) at intersection with posterior margin of pygidium, narrows posteriorly, circular in cross section (Pl. 10, figs 10, 14), in lateral view spine is upturned from horizontal plane, sculpture of fine, densely spaced lines arranged in a chevron pattern aligned with sagittal axis covers dorsal and ventral surface of spine, point of chevrons directed anteriorly on dorsal surface and directed posteriorly on ventral surface, sculpture nearly effaced on ventral surface of spine at intersection with posterior margin of pygidium (Pl. 10, fig. 15); in ventral view broad doublure visible (Pl. 10, figs 6, 15), widest opposite first and second segments, tapers dramatically posteriorly, with proximal portion strongly upturned toward ventral surface of pygidium, prominent sculpture of raised lines oriented roughly parallel to inner margin of doublure present along interior and external margins, sculpture of more widely spaced anastomosing lines present medially on widest portion of doublure. Discussion. As discussed above, sclerites assigned to P. pogonipensis are unlikely to be confused with those of the cooccurring P. ludificatus as the latter species is much more common. The pygidia described below as Pseudoolenoides cf. dilectus also cooccur, but comparison of the cranidium, librigenae, and pygidia grouped as P. pogonipensis to those of the broadly similar P. aspinosus reveals essential similarity and permits considerable confidence in the association. Also as discussed above, three cranidia from high in the Juab Formation at Ibex illustrated by Fortey and Droser as P. aspinosus (1996, fig. 12.2, 12.4, 12.6) and Acidiphorus ? lineotuberculatus (1999, fig. 4.20) are very similar to the cranidium of P. pogonipensis . We have previously demonstrated (Adrain and McAdams, 2012) that Psephosthenaspis glabrior Fortey and Droser, 1996, occurs at both of the same horizons, albeit with some minor morphological differences on the pygidium. The situation is similar for Pseudoolenoides pogonipensis . Only one cranidium has been found at the type horizon (Pl. 9, figs 7, 8, 10, 13) and, while it is quite small, it is certainly holaspid. The main difference between it and the upper Juab specimens is that its glabella is shorter and slightly more expanded laterally, and clearly stops short of the anterior border furrow, while in the older specimens the front of the glabella overhangs the rear of the border. The Juab specimens also have somewhat coarser tuberculate sculpture. Apart from these differences the specimens are very close in all other respects, and if they are not conspecific, it seems certain that the upper Juab material represents a species very similar to P. pogonipensis . For the present we tentatively assign them to the species. More material from both horizons would be required to assess the relationship with greater confidence. Pseudoolenoides pogonipensis was compared with P. ludificatus above. It differs from P. aspinosus in the possession of a much smaller glabella, an anterior border which is nearly evenly curved on its anterior margin, versus clearly nasute, slightly sparser tuberculate sculpture on the glabella, frontal areas mostly lacking tuberculate sculpture versus with prominent tubercles, a less well impressed eye ridge, a weakly expressed fixigenal boss in front of the eye ridge, a shorter SO but longer LO; a librigena with finer tuberculate sculpture and a much more posteriorly lobate posterior border with a strong accessory furrow; and a pygidium with a broader border anteriorly, shallower border furrow, and much longer posteromedian spine. : Published as part of Adrain, Jonathan M. & Karim, Talia S., 2012, 3467, pp. 1-97 in Zootaxa 3467 on pages 19-22 : {"references": ["Adrain, J. M. & McAdams, N. E. B. (2012) The Lower Ordovician (upper Floian) bathyurid trilobite Aponileus Hu, with species from Utah, Texas, and Greenland. Zootaxa, 3293, 1 - 67.", "Fortey, R. A. & Droser, M. L. (1996) Trilobites at the base of the Middle Ordovician, western United States. Journal of Paleontology, 70, 73 - 99."]}