Catillicephala cifellii Westrop & Dengler 2022, sp. nov.
Creators: name: Westrop, Stephen R.
name: Dengler, Alyce A.
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Trilobita
Ptychopariida
Catillicephalidae
Catillicephala
Catillicephala cifellii

description: Catillicephala cifellii sp. nov.
Figs. 1–3.
Zoobank LCID: urn:lsid:zoobank.org:act: 4B4919F0-DFB7-4569-B8 B1-1A2DE79BACFD
Etymology: In honour of Richard Cifelli upon his retirement and in recognition of his studies of Cretaceous mammals.
Type material: Holotype: GSC 142512, well preserved cranidium (Fig. 1A). Paratypes: five cranidia (GSC 142513–142515, Fig. 1; GSC 142517, Fig. 2B; GSC 142519, Fig. 2D), five pygidia (GSC 142520– 142524, Fig. 3) from boulder BPS 467; one cranidium (GSC 142516, Fig. 2A) from boulder BPS 468; one cranidium (GSC 142518, Fig. 2C) from boulder BPS 458. All from the type locality.
Type locality: Broom Point South, western Newfoundland, Canada.
Type horizon: Boulder BPS 467, Downes Point Member, Shallow Bay Formation, Guzhangian, Miaolingian, Cambrian.
Material.— The type material and two pygidia from boulder BPS 467; two cranidia and two pygidia from boulder BPS 458. All from the type locality.
Diagnosis.— Catillicephala with ovoid glabella, occipital ring subtriangular, drawn out posteriorly into stout spine, and short, narrow anterior border tapered laterally.
Description.—Strongly convex cranidium subtrapezoidal in outline (excluding LO), with curved anterior margin; preoccipital glabella length 54% (51–58%) maximum cranidial width across posterolateral projections. Frontal area represented only by very narrow, rim-like anterior border. Anterior border furrow finely etched, merges with preglabellar furrow; axial furrows shallow but clearly defined grooves, bowed gently outwards. Glabella barrel-shaped in outline, with outwardly curved flanks and gently rounded anteriorly; inflated, standing well above adjacent fixigenae in anterior view (e.g., Figs. 1A 3, 2B 1); width at anterior tip of S1 equal to 89% (81–94%; lower values in smaller specimens) preoccipital length. LO extended into stout, upwardly curved, triangular occipital spine in larger individuals (e.g., Figs. 1A 1, 2D). SO curved gently backwards, shallow, defined in part by break in slope between LO and preoccipital glabella, particularly on larger specimens (e.g., Fig. 1A). Lateral glabellar furrows barely perceptible on all but the smallest specimens (e.g., Figs. 1A 1, B, 2B 3, D). S1 geniculate, termination short of LO; S2 curved gently forward; S3 straight, directed obliquely forward from axial furrow. L1–L3 without independent convexity, maximum lengths (exsag.) roughly equal. Palpebral area of fixigenae narrow, equal to 25% (21–32%; higher values in smaller specimens) of glabellar width at anterior tip of S1, curved downwards in anterior view (e.g., Figs. 1A 3, 2B 1). Palpebral lobe narrow tr.), gently curved, length equal to 20% (16–24%) of preoccipital glabella length and centred opposite S2; palpebral furrow shallow, defined in part by break in slope between lobe and adjacent palpebral area. Palpebral ridge weakly convex, extends obliquely forward to intersect axial furrow near anterior end of glabella. Anterior branches of facial suture short, convergent; posterior branches divergent before curving backward at posterior border furrow to become subparallel. Postocular fixigenae broadly triangular in outline, cranidial width at palpebral lobe 77% (74–80%) maximum width of cranidium; posterolateral projection flexed sharply downward in anterior view (e.g., Fig. 1A 3). Posterior border furrow narrow, oblique, deep groove adaxially, shallowing abruptly abaxially and curving forward. Posterior weakly convex, expanding abaxially, with minimum length near axial furrow 28% (22–33%) of length at point where border furrow shallows. External surface other than furrows finely pitted, augmented with coarse granules on smaller specimens (e.g., Fig. 2C 1).
Pygidium strongly arched, semicircular in outline, length equal to 70% (65–78%) of maximum width, with anterior margin angled back, and conspicuous articulating facet at anterior corner. Axis inflated, rising well above pleural field; gently tapered and well-rounded posteriorly; long, overhanging posterior margin slightly on largest specimens (e.g., Fig. 3A 1, B 2), with width at anteriormost axial ring equal to 37% (34–40%) of maximum pygidial width. Articulating half-ring conspicuous, roughly semielliptical in outline; articulating furrow broad, roughly equal in length to half-ring. Broad, transverse ring furrows generally faint. Up to four rings and a terminal piece comprising at least two segments evident (e.g., Fig. 3A 1, B 2). Pleural field flexed downward; one well-defined pleural furrow expressed on external surface, remainder faint, although better defined on internal moulds. Border furrow faint but clearly defined; border downsloping. External surface save for furrows finely pitted; posterior edge of border with terrace ridges (e.g., Fig. 3B 1).
Ontogeny.—A series of differently sized cranidia show that the occipital spine develops during holaspid ontogeny. The smallest cranidium (Fig. 1D) has a short, aspinous LO that occupies only 21% of glabellar length, although there is an ill-defined node present. LO becomes longer (occupying 24% of glabellar length) and more triangular in outline in a somewhat larger specimen (Fig. 1C 1) but, although a node may be present, it is not yet spinose. By the time a distinct spine appears, LO accounts for 32% of glabellar length Fig. 2D), and the incompletely preserved spine of the larger holotype is also part of a very long LO (Fig. 1A 1). The axial furrows become increasingly bowed outwards, producing a distinctly barrel-shaped glabellar outline (compare Fig. 1A 1, B, C 1, D). Smaller individuals have better defined lateral glabellar furrows (Fig. 1C 1, D). The pygidial axis is very long in all specimens. It terminates just short of the pygidial margin in smaller specimens (e.g., Fig. 3C 2) but extends to overhang the margin slightly in larger individuals (Fig. 3A 1, B 2). Remarks.—The conspicuous glabella that overhangs a very short anterior border and pygidium with a strongly convex, gently tapered axis ally Catillicephala cifellii sp. nov. with the other members of the genus that were revised by Westrop and Dengler (2014a). The spinous, triangular occipital ring of larger individuals (Figs. 1A, 2D) is unique. Catillicephala cifellii sp. nov. is most like C. rotunda (Rasetti, 1946) from the Grosses-Roches Formation, Métis-sur-Mer area, Quebec. The latter species has a tapered occipital ring with a rounded to bluntly pointed terminus (e.g., Westrop and Dengler 2014a: figs. 3D, 4B, G) that resembles the condition in small specimens of C. cifellii (Fig. 1D), albeit without an occipital node. Unlike C. cifellii, the occipital ring of C. rotunda does not develop a spine, even in the largest individuals. In addition, C. rotunda has a more bulbous glabella that is well-rounded anteriorly, and has narrower (tr.) posterior area of the fixigena. In the largest pygidia of C. rotunda, the axis terminates short of the posterior margin (e.g., Westrop and Dengler 2014a: fig. 5A–C), whereas similarly sized pygidia of C. cifellii have longer axes that overhang the pygidial margin (e.g., Fig. 3A, B)
Compared to C. cifellii, C. impressa (Rasetti, 1946) has a far more rounded preoccipital region of the glabella that is subcircular in outline and usually has a medial backward expansion that constricts the occipital furrow (e.g., Westrop and Dengler 2014a: figs. 7A, I, 8E, 9B). The anterior border furrow of C. impressa is effaced medially across almost the entire width of the glabella (e.g., Westrop and Dengler 2014a: figs. 7D, 8F, I, 9C, F, I), whereas C. cifellii has a shallow but complete border furrow (Figs. 1A 3, C 3, 2A 3).
Catillicephala shawi Westrop and Dengler, 2014a, differs from C. cifellii in having a subquadrate glabella that expands gently forward, an occipital furrow that shallows medially, and, as in C. impressa, the anterior border furrow is effaced in front of the glabella (e.g., Westrop and Dengler 2014a: figs. 14, 15). Like C. cifellii, the pygidium of C. calva Westrop and Dengler, 2014a, has a convex axis that overhangs the posterior margin. The cranidia of these two species are differentiated readily. In addition to lacking an occipital spine, C. calva has a relatively narrow, forwardly expanding glabella that contrasts with the barrel-shaped glabella of C. cifellii (compare Fig. 1A, B with Westrop and Dengler 2014a: fig. 19).
Stratigraphic and geographic range.— Type locality and horizon only.
description: Published as part of Westrop, Stephen R. & Dengler, Alyce A., 2022, A new Cambrian catillicephalid trilobite from the Shallow Bay Formation of western Newfoundland, Canada, pp. 27-33 in Acta Palaeontologica Polonica 67 (1) on pages 28-32, DOI: 10.4202/app.00922.2021, http://zenodo.org/record/10626754