Jincella? applanata (Hicks in Salter & Hicks, 1869)

Unger, Tanja, Hildenbrand, Anne, Stinnesbeck, Wolfgang & Austermann, Gregor, 2022, Biostratigraphy and taxonomy of polymerid trilobites of the Manuels River Formation (Drumian, middle Cambrian), Newfoundland, Canada, Geodiversitas 44 (33), pp. 1051-1087 : 1060-1062

Jincella? applanata (Hicks in Salter & Hicks, 1869)

( Fig. 6 )

Conocoryphe applanata Hicks in Salter & Hicks, 1869: 53, 54, pl. 2, figs 1, 2, 4, 5.

Solenopleura applanata – Reed 1900: 252, 257. — Illing 1915: 432, pl. 37, figs 8, 9. — Nicholas 1915: 463, 464, pl. 39, figs 8, 9 (?). — Lake 1931: 137-139, pl. 17, figs 2-12. — Cobbold & Pocock 1934: 365, pl. 43, fig. 1 (?).

Solenopleura cf. applanata – Illing 1915: 433, pl. 37, fig. 10 (?).

Parasolenopleura? applanata – Martin & Dean 1988: 20, 21, pl. 1, fig. 14; pl. 3, figs 3, 6, 8, 14, 15.

Bailiaspis venusta – Cotton 2001: pl. 4, fig. 7.

Parasolenopleura applanata – Young et al. 2002: pl. 4, fig. x.

Parasolenopleura cf. applanata – Young et al. 2002: pl. 4, fig. iv.

Solenopleura cf. applanata –Rushton & Berg-Madsen 2002: 341, figs5d-f.

Jincella applanata – Fletcher 2006: pl. 34, fig. 36.

Brunswicki (Jincella) applanata – Fletcher 2007: 50, 51, figs 7C- G, K-M, T.

Solenopleura? applanata – Weidner & Nielsen 2014: 82, 83, figs 50 A-I.

SYNTYPES. — Specimen BGS 7004 (British Geological Survey, Keyworth, United Kingdom) originally figured by Salter & Hicks (1869), counterpart BGS 7005 figured by Lake (1931) and SM A 271, A 3238 and A 3248 (Sedgwick Museum of Earth Sciences, Cambridge, United Kingdom). All syntypes were identified by Weidner & Nielsen (2014). From the Menevian of Port-y-rhaw , St. David’s, Wales.

DIAGNOSIS. — Glabella parabolic, with three pairs of furrows; preglabellar field less wide than the associated anterior border; surface finely granulated with scattered granules (based on Salter & Hicks 1869; Fletcher 2007, with modifications).

MATERIAL EXAMINED. — 355 cranidia of Jincella ? applanata (for NFM numbers see Appendix 1) . Three are attached to the thorax and one has one librigena attached ( NFM F-3595). The specimens are well to very well-preserved as internal casts and moulds. Some are pyritized. All specimens range between 4.44 and 16.67 m ( Fig. 2 ) of the Manuels River Formation, type locality, Conception Bay South, Newfoundland, Canada.

OCCURENCE. — Jincella ? applanata is documented from southeastern Canada, eastern Newfoundland, in the Tomagnostus fissus , Ptychagnostus atavus , Paradoxides hicksi and Paradoxides davidis zones ( Martin & Dean 1988; Fletcher 2006, 2007). It has also been reported from the United Kingdom in Wales ( Salter & Hicks 1869; Nicholas 1915; Young et al. 2002) and England ( Tomagnostus fissus to Solenopleura brachymetop zones and Ptychagnostus atavus Zone ; Illing 1915; Rushton & Berg-Madsen 2002), and from Denmark ( Acidusus atavus Zone ; Weidner & Nielsen 2014).

DESCRIPTION

The size of the cranidium ranges from 3.5 mm to 16.0 mm width and from 2.1 mm to 12.0 mm length, while the cranidial shape varies from rounded to trapezoidal. In some rounded shaped cranidia the fixigena in front of the glabella are separated by a shallow depression from each other. Eye ridges are faint and frequently even absent in specimens with preserved ornamentation. Some moulds and occasional internal casts show vein-like markings in front of the eye ridges. One specimen (NFM F-3595) is preserved with an attached librigena, also showing vein-like markings on the cranidium and the librigena. The glabella is always more domed than the cheeks. The posterior pair of glabellar furrows bend down slightly towards the occipital ring. The second pair of furrows only reaches half the length of the posterior ones and parallels these. The anterior pair is shortest and crosses the glabella more horizontally. Some specimens show a small node on the occipital ring. Where preserved, ornamentation consists of more or less densely packed scattered granules on the cephalon, and scattered granules on the thorax.

REMARKS

Jincella ? applanata was first assigned to the genus Conocoryphe Hawle & Corda, 1847 , by Salter & Hicks (1869). Reed (1900) discussed Conocoryphe and concluded that J.? applanata was better assigned to Solenopleura Angelin, 1854 . Subsequent authors assigned the species to Parasolenopleura Westergård, 1953 ( Martin & Dean 1988; Young et al. 2002), Jincella Šnajdr, 1957 ( Álvaro et al. 2004; Fletcher 2006), or Brunswickia (Jincella) Šnajdr, 1957 ( Fletcher 2007) . Martin & Dean (1988) and Weidner & Nielsen (2014) marked the genus with a question mark, which reflects the uncertainty regarding the generic ranking. As pointed out by Rushton & Berg-Madsen (2002), Fletcher (2007) and Weidner & Nielsen (2014), among other authors, note that the family is in need for a revision. Therefore, the present material is here provisionally assigned to the genus Jincella . Regarding the authorship of the species, it is remarkable that several authors (e.g., Illing 1915; Lake 1931; Fletcher 2007) attribute it to Salter. In Salter & Hicks (1869), a H.H. abbreviation following the description of J.? applanata clarifies that Henry Hicks has written this part. Consequently, the correct authorship must be J.? applanata (Hicks in Salter & Hicks, 1869) as done by Weidner & Nielsen (2014).

Illing (1915) figured one juvenile cranidium assigned to J.? applanata . The image on pl. 37, fig. 10, is overexposed and the assignment therefore questionable. Nicholas (1915) presented drawings of two cranidia, both attached to the thorax. In his plate 39, figures 8, 9, the preglabellar area is relatively wide. This is unlike the diagnosis of J.? applanata , therefore the assignment is considered as questionable. Lake (1931) presented drawings of specimens previously figured by Salter & Hicks (1869), Nicholas (1915) and Illing (1915). These drawings show a preglabellar area wider than in the original figures. As Lakes’ (1931) description matches J.? applanata , the wider preglabellar area is here considered to be a matter of uncertainty in the author’s drawings. Cobbold & Pocock (1934) listed measurements of one illustrated specimen. The drawing of the cranidium has a wide preglabellar area and the eyes are situated close to the glabella. This does not match the characteristic short preglabellar area and the range of cranidial outlines known from J.? applanata . Therefore, the specieslevel assignment is questionable. Cotton (2001) figured one cranidium assigned to Bailiaspis venusta Resser, 1937 , without presenting a description. However, the figured specimen has eyes and can therefore not be assigned to Bailiaspis , nor to its family Conocoryphidae Angelin, 1854 . Instead, it matches J.? applanata and is here assigned to this species.

Figures

FIG. 6. — Jincella? applanata (Hicks in Salter & Hicks, 1869); A, B, internal cast and mould of the same specimen, glabellar furrows and ornamentation on internal cast preserved (NFM F-3398 from 8.94 m); C, internal cast of a cranidium attached to the thorax, ornamentation and occipital node preserved (NFM F-3401 from 8.94 m); D, internal cast of a cranidium with one librigena attached, venulose markings on librigena and cranidium anterior of eye ridges preserved (NFM F-3595 from 15.30 m); E, internal cast of a trapezoidal shaped cranidium, occipital ring and venulose markings anterior of eye ridges preserved, NFM F-3594 from 15.30 m; F, internal cast of trapezoidal shaped cranidium, densely packed scattered granuels preserved, fixigenae slightly separated (NFM F-2949 from 6.15 m); G, internal cast of a round shaped cranidium, some granuels have dents preserved, fixigenae slightly separated (NFM F-3297 from 6.18 m); H, internal cast of a round shaped cranidium, occipital ring and ornamentation preserved (NFM F-3616 from 9.33 m); I, mould of a round shaped cranidium, occipital node and ornamentation preserved (NFM F-3405 from 8.94 m). Scale bars: 1 mm.

FIG. 2. — Lithology of the type locality of the Manuels River Formation, range chart of the here described species. Agnostid biozones from Hildenbrand et al. (2021) and polymerid biozones from Howell (1925).