128 1944
1968 1984
1990
1992 1993 1998
Journal of Paleontology 91(1):116–145
Retiolites (Pseudoretiolites) perlatus; Bouček and Münch, p. 24, pl. 1, figs. 4–7; text: figs. 8a–e, 9c–e.
Pseudoretiolites perlatus; Obut and Sobolevskaya, p. 74, pl. 7, figs. 6–9.
Pseudoretiolites daironi (Lapworth); Chen, p. 49, pl. 6, figs. 9, 12, pl. 7, figs. 1, 3–6.
1987a Pseudoretiolites cf. decurtatus Bouček and Münch; Lenz and Melchin, pl. 1, figs. 2, 3(?), 4–8.
Pseudoretiolites daironi (Lapworth); Ge, p. 79, pl. 8, fig. 20, pl. 9, figs. 4, 5.
Pseudoretiolites cf. decurtatus Bouček and Münch; Bates and Kirk, p. 120, pls. 7–11, figs. 120–164.
Pseudoretiolites perlatus; Loydell, p. 61, text: fig. 13, fig. 3 (see for an expanded synonymy list up to 1993).
Pseudoretiolites perlatus; Štorch, p. 225, pl. 6, fig. 1, text: fig. 6, fig. 8. [? pl. 6, figs. 7, 9].
Materials.—12 specimens are assigned to this species, all but two of which are immature.
Occurrence.—L. convolutus Zone of Rookery Creek, Cape Manning, an unknown locality, Cornwallis Island, and Dundas Island. Four specimens are identified as
P.cf. perlatus from L. convolutus Zone, Rookery Creek. Found in the middle to upper C. curtus Zone in northern Siberia, and the D. simulans and P. leptotheca zones of Czech Republic, and, more commonly, the L. convolutus Zone of Arctic Canada, Great Britain, Czech Republic, Germany, and south China.
Description.—Tubarium up to at least 6.4mm long, proximal portion more-or-less triangular in profile, widening steadily from 1.2 to 1.4mm across first thecal pair and to 3.0–3.1mm across fifth thecal pair, which is the maximumwidth observed in our specimens. 2TRD 1.0mm at the first thecal pair, to an observed maximum of 1.5mm. Prosicula commonly preserved, 0.3–0.37mm long, with longitudinal rods. Virgella 0.5mm long, sometimes with preserved fringes of metasicular fusellar tissue. Ancora umbrella deep, reaching the level of the aperture of the prosicula or higher, four to five whorls of spiral lists, 0.8–1.1mm diameter. Small, ventral orifices occur between ancora umbrella and first thecal pair. Medium-sized, rounded orifices may be present on both lateral walls above the ancora. Thecae with straight, outward-inclined ventral walls.
Ventral walls of thecae consist of a mid-ventral list and three to five paired zigzag lists, inclined ~80o to nema for first two thecal pairs, and 50o–60o distally. Mid-ventral list of theca 11 originates from within the inside surface of the ancora
umbrella. Pleural lists present, inclined inward. Ancora sleeve reticulum a coarse meshwork throughout, with mesh sizes generally ranging from 0.25–0.45mm, made of five- to six-sided polygons. Stomata present, rounded, more-or-less equidimensional, ~0.4–0.6mm across, not elevated above reticulum.
Remarks.—Although there are no fully mature specimens in the collection, the moderately rapid widening of the tubarium for at least the first six thecae, the moderate angle of thecal ventral walls to the nema, and the thecal spacing match well with the material described by Elles and Wood (1908, pl. 34, figs. 10a–f). The type specimen, illustrated by Nicholson, 1868, and re- illustrated by Elles and Wood (1908, pl. 34, fig. 10a), is without the proximal end. In comparison with the very well-preserved material described from the Czech Republic (Štorch, 1998), the Arctic specimens are in general agreement, differing in being slightly narrower at the level of the fifth thecal pair, and possessing a slightly closer thecal spacing. The material described from Wales by Loydell (1993) is fragmentary, but the distal specimens match well with those of this species described from the Czech Republic. In comparison with Chinese material (Chen, 1984; Ge, 1990), both the Arctic and Czech specimens differ in having fewer zigzag lists in the thecal ventral wall, and in widening much more rapidly, but are otherwise very similar. The details of the morphology of this taxon were
documented by Bates and Kirk (1992, specimens identified as Pseudoretiolites cf. decurtatus), who clearly illustrated the details of the thecal framework, the traces of metasicular tissue preserved on the virgella (e.g., their figs. 122, 126, 128, 129), and the very finely striated list surfaces (see also Lenz and Melchin, 1987a). A number of authors have also shown that mature specimens commonly have continuous membranes preserved on the thecal walls (e.g., Elles and Wood, 1908; Bouček and Münch, 1944).
Pseudoretiolites decurtatus Bouček and Münch, 1944 Figure 9.1, 9.2, 9.4, 9.5, 9.7, 9.8
1944 1952
1982 1984
Retiolites (Pseudoretiolites) decurtatus Bouček and Münch, p. 30, text-figs. 3a–c, 9a.
Pseudoretiolites decurtatus;Münch, p. 74, pl. 12, fig. 5. Retiolites decurtatus; Lenz, p. 32, fig. 15F.
1987b Pseudoretiolites cf. decurtatus; Lenz and Melchin, fig. 3, figs. A–G.
Pseudoretiolites decurtatus; Chen, p. 50, pl. 7, figs.4,7.
?1998 Pseudoretiolites perlatus (Nicholson); Štorch, p. 225, pl. 6, figs. 7, 9 [non fig. 1, text-fig. 6, fig. 8].
Figure 10. Scanning electron microscopy images of Pseudoretiolites hyrichus n. sp.: (1, 3) paratype GSC137632, (1) enlargement showing deep ancora umbrella and partially preserved metasicula, showing longitudinal rods on prosicula (a), and base of median ventral list of th11 attached to inner surface of ancora umbrella (b), (3) stereopair of specimen with two thecal pairs, complete ancora umbrella with five spiral whorls, and paired lateral orifices; prosicula and most of metasicula preserved, section MCM96-9, 1.8–1.9 m, L. convolutus Zone; (2) paratype GSC137633, immature specimen, proximal view of ancora umbrella with six spiral whorls, and partially preserved metasicula, section MCM96-9, 1.8– 1.9m above, L. convolutus Zone; (4) paratype GSC137634, stereopair of distal part of tubarium with three thecal pairs, section MCM96-9, 1.8–1.9 m, L. convolutus Zone; (5, 6) holotype GSC137635, (5) stereopair, immature specimen with very well preserved ancora umbrella with four spiral whorls, two thecal pairs, large paired lateral orifices, and prosicula and most of metasicula preserved, showing attachment of nema to connecting rods (a), pleural list (b), and mid-ventral list (c), (6) enlargement of part or proximal end showing smooth list surfaces and partially preserved metasicular fusellae, section MCM96-9, 1.8–1.9m above reference, L. convolutus Zone.
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