Neogothograptus alatiformis Lenz and Kozłowska−Dawidziuk, 2004

Kozłowska, Anna, Lenz, Alfred & Melchin, Michael, 2009, Evolution of the retiolitid Neogothograptus (Graptolithina) and its new species from the upper Wenlock of Poland, Baltica, Acta Palaeontologica Polonica 54 (3), pp. 423-434 : 432-433

Neogothograptus alatiformis Lenz and Kozłowska−Dawidziuk, 2004

Fig. 9 .

2004 Neogothograptus alatiformis sp. nov.; Lenz and KozłowskaDawidziuk 2004: 18–19, pls. 11–16: 16.

Holotype: GSC 125988 .

Type locality and age: Northeastern Cornwallis Island, talus concretion, unnamed creek, Arctic Canada; Lower Ludlow, Lobograptus progenitor and L. scanicus biozones.

Material.—Dozens of fragments of rhabdosomes from Baltic erratic boulder 62 from Jarosławiec, Poland, Ludlow; co−occurs with Saetograptus chimaera ?; several larger fragments from Gołdap borehole, depth 1246.3 m, co−occur with Saetograptus chimaera and Lobograptus progenitor .

Comments.—The material consists of fragments of the proximal end, thecal walls, apertural processes, and appendix ( Fig. 9 ). The measurements and proportions of these agree with the type material.

Discussion.—The uniqueness of the N. alatiformis rhabdosome, originally described from Arctic Canada, is so distinctive that, with the exception N. ornatus Maletz, 2008 , the Jarosławiec fragments cannot belong to any other species. From N. ornatus , N. alatiformis is distinguished by being much shorter (only two pairs of thecae), possessing a very short appendix, and generally larger and more complex genicular processes. Most importantly, the first pair of processes occurs below the first thecal pair.

Stratigraphic and geographic range.—Ludlow, Lobograptus progenitor Biozone : Baltic erratic boulder 62 Jarosławiec, and Gołdap borehole of Poland; Arctic Canada; Yunnan, China.

Figures

Fig. 9. SEM micrographs of fragments of rhabdosomes of Neogothograptus alatiformis Lenz and Kozłowska−Dawidziuk, 2004, Baltic erratic boulder 62 from Jarosławiec, Poland, Ludlow. A. Proximal end with outer ancora, lateral view; ventral view (A1), showing ventral orifice closed by reticulum (A2), enlargement of ancora list (A3). B. Enlargement of appendix, distal view (B1), lateral view of appendix (B2). C. Singular apertural process on geniculum, lip with short mid−ventral visible from inside (C1); inside view of fusellar nature of apertural process (C2). D. Ventral and lateral part of rhabdosome with aperture and apertural process.