Newfoundlandops karimae, Adrain & Pérez-Peris, 2021

Adrain, Jonathan M. & Pérez-Peris, Francesc, 2021, Middle Ordovician (Darriwilian) cheirurid trilobites from the Table Cove Formation, western Newfoundland, Canada, Zootaxa 5041 (1), pp. 1-73 : 32-34

Newfoundlandops karimae n. sp.

Plates 11 , 12

2019 Sphaerexochus n. sp.; Adrain and Karim, fig. 4.11.

Material. Holotype, pygidium, GSC 135201 (Pl. 12, figs 8, 11, 12, 15, 18), and assigned specimens GSC 135190– 135199 , 135202–135206 , 135354 , all from horizon TCM 18.

Etymology. For Talia Karim.

Diagnosis. As for genus.

Description. Cranidial measurements were made on the specimens of Plate 11 , figures 1, 4, 16. For the measurement of the cranidial width, in the specimens where the cranidium was preserved only on one side, the distance to the sagittal line from the side was doubled. Cranidium broadly semicircular in outline, wider than long, with sagittal length 64.3% (58.5–72.2%) maximum width, maximum width across the genal angles excluding the genal spines, vaulted dorsally in medial part; fixigenal field strongly downturned in anterior view, anterior part sloping downwards from the horizontal; anterior border short (sag., exsag.), describing a broad anteriorly directed arch, overhung by the anterior part of the glabella in dorsal view except for the lateral regions, medial region deflected dorsally in anterior view (e.g., Pl. 11, fig. 15), dense, equally distributed sculpture of tiny granules on entire surface; anterior border short (sag., exsag), deeply incised, shallower medially, describing an anteriorly directed arch; glabella subcircular in outline, maximum width across L2, sagittal length 66.6% (56.9–72.2%) maximum width (tr.); medial part, from L1 to the medial part of L2, slightly forwardly expanding; S3 tapering forward, posterolateral corners rounded, anterior margin describing a broad arch, posterior margin with central part transverse and abaxially behind L1 slightly bowed posteriorly; glabella strongly dorsally vaulted, anterior to S1 sloped downward from the horizontal (e.g., Pl. 11, fig. 18), surface densely covered by tiny granules equally distributed across the surface; S1–S3 well defined, deeply incised, relatively short (exsag.), extending about one quarter of the glabellar width; S1 longer (exsag.) and deeper than S2/S3, extending further adaxially than S2/S3, transversely directed with the proximal end turned posteriorly and followed by a shallow depression that connects with SO and isolates L1 from the median glabellar lobe (e.g., Pl. 11, figs 4, 16); S2/S3, shallower, shorter (exsag.) and narrower than S1, running subparallel to S1 but more transversely directed in proximal part; SO similar in length (sag., exsag.) and depth to S1, transverse in medial part, slightly bowed posteriorly laterally; LO subrectangular in outline, longer sagittally, shorter exsagittally, anterior margin transverse medially and posteriorly bowed laterally, posterior margin slightly arched posteriorly; L1 subquadrate in outline, slightly longer (exsag.) than L2, anterior margin transverse, posterior margin bowed posteriorly, slightly vaulted dorsally; L2 and L3 subrectangular in outline, similar in shape to L1; L2 slightly wider than L3, lateral margins slightly bowed laterally; frontal lobe semicircular in outline, slightly shorter (sag.) than the rest of glabellar lobes; axial furrow deeper and wider posteriorly, similar to S1, narrowing and shallowing anteriorly to S1 with similar depth to S2 and S3; fixigenal field triangular in outline, with dense sculpture of tiny granules along with a few larger tubercles (e.g., Pl. 11, fig. 12), interocular fixigena relatively long (exsag.), extremely narrow, posterior fixigena subquadrate, length similar to that of interocular fixigena, wider than interocular fixigena, strongly downturned (e.g., Pl. 11, fig. 15), anterior margin directed slightly posteriorly; posterior border furrow short (exsag.), deeply incised, longer and deeper proximally, shallower distally, transversely directed adaxial to genal angle, then smoothly anteriorly curved; lateral border furrow directed anterolaterally, relatively narrow; posterior border with proximal part near LO and below L1 wedge shaped, rapidly lengthening (exsag.) distally, with anterior margin directed forwards and outwards, until maximum near genal spine, anterior margin almost transverse and posterior margin slightly running posteriorly, distally beyond the genal angle with smooth anterior curvature; genal spines of moderate length, directed posteriorly and slightly laterally, widest at base, tapering to the tip, ending in a pointed tip; lateral border short (exsag.), directed anteriorly and slightly laterally, wider (tr.) near the genal angle; posterior border, genal spine and lateral border share sculpture similar to that of fixigenal field; palpebral lobe very narrow (tr.), elongate (exsag.), in lateral view describing an arch directed dorsally (e.g, Pl. 11, fig. 18), posterior end set slightly anteriorly to distal end of S1, anterior end set opposite S2, no eye ridge present; palpebral furrow narrow, deeply incised, running length of palpebral lobe; doublure beneath LO short (sag), approximately half of the sagittal length of LO, smooth; doublure in posterior border extremely short (sag.), distally beneath genal angle slightly expanded forming a triangular corner (e.g., Pl. 11, fig. 22).

Librigena elongate and narrow; eye relatively large, set anteriorly, elevated dorsally, differentiated from the field by a narrow and extremely shallow furrow (e.g., Pl. 11, fig. 14); librigenal field subtrapezoidal in outline, margin across base of the eye slightly shorter than margin next to border furrow, sloping downwards from the eye to the border with respect to horizontal, with dense sculpture of small granules equally distributed across the surface; border furrow broad, very shallow, almost effaced, describing a laterally directed arch, sculpture similar to that of field; lateral border relatively wide, elongate, inflated, with sculpture similar to border furrow; anterior projection short, narrow, curved laterally; posterior facial suture long, broadly describing an outwardly convex arch, subtle change in slope opposite border furrow; anterior facial suture short, describing a curved outwardly arch; doublure expanded with similar width as the border (e.g., Pl. 11, fig. 23), describing an outwardly directed arch, smooth.

Rostral plate unknown.

Hypostomal measurements were made on the specimen of Plate 12 , figure 3. Hypostome subquadrate in outline, slightly wider than long, with sagittal length 83.3% maximum width across lateral shoulders, moderately vaulted anteriorly in medial part; anterior border gently arched anteriorly, short (sag., exsag.), merging smoothly with anterior wings; anterior border furrow very short (sag.), gently bowed anteriorly similar to anterior border, very shallow; anterior wings small, triangular in shape, slightly pointed dorsally (e.g., Pl. 12, fig. 7); lateral notch well defined, gently concave dorsoventrally; posterior wings not prominent, deflected dorsally and inwards; middle body subtrapezoidal in outline, shorter (sag.) than wide (tr.) with sagittal length 63.2% middle body maximum width, moderately vaulted ventrally, especially anteriorly, anterior lobe larger than posterior lobe; anterior lobe ovoid in outline, wider than long, longer (sag.) medially, tapering laterally, maximum width across anterolateral corners, anterolateral corners pointed, anterior margin gently curved anteriorly, posterior margin gently curved posteriorly; posterior lobe slightly shorter (sag.) and narrower than anterior lobe, anterior margin slightly bowed posteriorly, posterior margin arched posteriorly with the median part almost transverse; middle furrow separates anterior and posterior lobes of the middle body, short (sag.), shallow, almost effaced medially, describing a slightly posteriorly curved arch; maculae ovate in outline; border furrow deeply incised anteriorly across the middle body, shallowed posteriorly, wide, narrower anteriorly and expanding slightly posteriorly; lateral border expanded, slightly wider across the lateral shoulder (e.g., Pl. 12, fig. 3), outer margin subtly arched outward at shoulders; posterior border long (exsag.), bilobate in outline (e.g., Pl. 12, figs 2, 3), medial part constricted, shorter (sag.), distally expanded with posterior margin describing a prominent posteriorly directed arch, slightly sloping ventrally from the horizontal; middle body and lateral border with sculpture of dense medium sized granules; beneath lateral and posterior borders doublure broad with similar width as lateral and posterior border (e.g., Pl. 12, fig. 2).

Thorax unknown.

Pygidial measurements are based on the specimens of Plate 12 , figures 8, 10. Pygidium approximately semicircular in outline, broad (tr.), relatively short (sag.), with sagittal length (excluding articulating half-ring) 45.5% (44.1–46.8%) maximum width, slightly dorsally vaulted in anterior axial region, posteriorly sloping down from the horizontal (e.g., Pl. 12, figs 9, 12, 13); fulcrum set close to axis, with pleura slightly downturned beyond the fulcrum; articulating half-ring longer medially with sagittal length 10.9% (10.3–11.5%) maximum pygidial length, tapering abaxially, anterior margin slightly bowed anteriorly in medial part, posterior margin slightly bowed posteriorly in medial part, describing a dorsally directed arch in anterior view; articulating furrow short (sag., exsag.), slightly longer medially, deeply incised laterally, slightly shallowing medially, subtly bowed posteriorly, nearly transverse; axis subtriangular in outline, with sagittal length 41.9% (41.4–42.3%) pygidial sagittal length and width 32.3% (32.2–32.3%) pygidial width, composed of three axial rings (e.g., Pl. 12, figs 1, 8, 10), vaulted anteriorly, gradually decreasing inflation posteriorly with posterior part almost flat, with dense sculpture of evenly distributed tiny granules, row of larger tubercles present in the posterior part of axial rings; first and second axial rings similar in shape, subrectangular in outline; first axial ring longer and slightly wider than second axial ring, medially slightly shorter (sag.) and subtly expanding forward, anterior margin slightly bowed posteromedially, posterior margin slightly bowed anteromedially, corners squared off; third axial ring semicircular in outline, narrower (tr.) and slightly shorter (sag.) than second axial ring, anterior margin transverse, posterior margin posteriorly curved; terminal piece absent; first inter-ring furrow slightly narrower (tr.) and with same length as articulating furrow, slightly broader medially, deeply incised, becoming shallower in medial part, running transversely; second inter-ring furrow similar to the first inter-ring furrow, slightly narrower (tr.) and shorter (sag.); axial furrow narrow, wider in the intersection with the inter-ring furrows and interpleural furrows, more deeply incised anteriorly opposite the first axial ring and shallowing posteriorly; three interpleural furrows, similar in width and depth to inter-ring furrow, with first interpleural furrow longer (sag.) and deeper, running posterolaterally, second interpleural ring shorter strongly curved backwardly, third interpleural furrow directed posteriorly; three pleural segments extended by thick flattened pleural spine, distally sloping down with respect to the horizontal, proximal part divided in anterior and posterior pleural segment by a pleural furrow; pleural furrow narrow (tr.), running anteriorly in the pleura from the intersection with the axial furrow to the fulcrum describing a posteriorly directed arch (e.g., Pl. 12, figs 1, 8, 10), deeper proximally and shallow distally, deeply incised in the first pleural segment, shallower in the second and shallowest in the third pleural segment; first pleural segment proximally similar in length (sag.) to axial ring, lengthening gradually distally, anterior margin transverse adaxial to fulcrum, posterior margin slightly convex anteriorly, proximally divided into anterior and posterior bands by pleural furrow; anterior band highly vaulted dorsally, distally extended by a thick pleural spine, tapering distally, anterior margin bowed anterolaterally, posterior margin running posterolaterally, slightly vaulted dorsally (e.g., Pl. 12, fig. 15), ovoid in cross section, distal tip slightly rounded; second pleural segment similar in shape to first pleural segment, with pleural spine curved more strongly posteriorly, anterior band less vaulted dorsally; third pleural segment subrectangular in outline, directed posteriorly, distal tip more gently rounded than the others; pygidial border expressed ventrally as a narrow rim, describing a narrow (tr.) posteriorly directed arch in the medial part, distally beyond the medial arch running anterolaterally, not visible dorsally; pleural segments with dense sculpture of small tubercles equally distributed in all over the surface, with a few larger tubercles aligned in a row (e.g., Pl. 12, figs 15, 16, 20); doublure very short, smooth, with medial arch slightly longer and strongly directed upwards; distal part shorter and directed downwards.

Discussion. See genus discussion.

Figures

PLATE 11

PLATE 12