Armadillidium sp.

Hyžný, M & Dávid, A, 2017, A remarkably well-preserved terrestrial isopod (Peracarida: Isopoda: Armadillidiidae) from the upper Oligocene of Hungary, with remarks on the oniscidean taphonomy, Palaeontologia Electronica 20 (1), pp. 1-11 : 4-5

Armadillidium sp.

Figures 3.1 -6, 4.1-3, 5.1

Material. The specimen studied ( MM 2015.513.1; collections of the Matra Museum of Hungarian Natural History Museum at Gyöngyös, Hungary) comes from the molluscan clay of the Wind Brickyard section at Eger ( Figures 1-2). It is preserved three-dimensionally in poorly lithified sand; no deformation is observed ( Figures 3.1 -6, 5.1). All cuticular surfaces are preserved .

Description. Body oblong-ovate, approximately twice as long as wide, lateral outlines subparallel, dorsal surface strongly vaulted and smooth. Cephalon not preserved, but presumed to have been wider than long (based on the slit in pereonite I). Pereonites distinctly wider than long, subequal, each being approximately 1.5 mm in length. No epimera separated on any pereonite. Epimera of pereonite I with acute posterior corner, without schisma. Pleon as wide as pereon. Pleonites 1 and 2 covered at sides by pereonite VII. Terminal segment of pleon (pleotelson) trapezoidal or triangular in shape, apparently tapering posteriorly, with broken posterior margin and probably not extending beyond epimera of pleonite 5. Uropods broken.

Remarks. The specimen is very well preserved; however, it lacks head and appendages, which are crucial for the taxonomy of oniscidean isopods as discussed by Schmidt (2002). Based on the comparisons discussed above it is assigned to the Armadillidiidae and identified tentatively as a representative of Armadillidium . The studied specimen shows overall similarity to Armadillidium vulgare (e.g., Sars, 1899, p. 189, pl. 81; Richardson, 1905, p. 666, figure 706; Van Name, 1936, p. 276, figures 157-158; Frankenberger, 1959, plate 2, figure 11; Hegna, 2010, figures 2A-B) and related species such as A. pulchellum ( Zenker, 1798) (e.g., Sars, 1899, p. 191, plate 83, figure 4). Close comparison, however, is not possible. Despite the fact that the chance of discovery of additional specimens is minimal, we refrain from erecting a new species based on the present material because of lack of sufficient number of distinguishing characters.

Figures

FIGURE 3. Armadillidium sp. from the upper Oligocene of Eger, Hungary (MM 2015.513.1). 1. Lateral (right) view. 2. Dorsal view. 3. Lateral (left) view. 4. Anterior view; note the missing cephalon. 5. Postero-dorsal view. 6. Posterior view. Roman numerals indicate pereonites; Arabic numerals refer to pleonites.