Rogneda falcata, BRUNET, 1965

Artois, Tom J., 2008, Revision of Rogneda Uljanin, 1870 (Rhabditophora, Eukalyptorhynchia, Polycystididae) with the description of seven new species, Zoological Journal of the Linnean Society 153 (1), pp. 1-28 : 5

THE FALCATA -GROUP

The falcata -group includes two unpigmented species from the western Mediterranean: R. acuta ( Figs 3D , 4E, F ) and R. falcata ( Figs 3C , 4G ). These species differ from the other species of Rogneda by the fact that stylet A consists of only one plate, and by a particular construction of stylet B. According to Brunet (1979), stylet A of R. acuta can easily be derived from that of R. falcata ‘by a simple regression’ of the proximal part of the stylet. Although such a process could be imagined, it is highly speculative. Actually, stylet A of R. acuta cannot be compared with that of any of the other species of Rogneda , while stylet A of R. falcata resembles stylet B of R. reticulata ( Fig. 8E ), but with the distal part of plate B1 lacking in R. falcata . Stylet B of the species of the falcata -group differs from that of all other species of Rogneda (except the species of the capulata -group) in that plate B2 is attached to the proximal end of plate B1. In R. falcata , plate B1 is sickle-shaped and plate B2 is digitiform. In R. acuta , stylet B is more of the typical form, with plate B2 being plate-shaped and distally forked.

Figures

Figure 3. Stylets of the representatives of the capulata- and the falcata-group. A, R. exilis (from the holotype). B, R. capulata (from the lectotype). C, R. falcata (from the holotype). D, R. acuta (from the holotype). Stylet A is indicated by an A, stylet B by a B. Plates B1 and B2 are indicated by a 1 and a 2, respectively. Scale bar = 25 Mm.

Figure 4. Stylets of R. minuta and of representatives of the capulata- and falcata-group. A, B, R. minuta (A from the neotype; B specimen from Marseilles). C, D, R. exilis [C, stylet B; D, stylet A (both from the holotype)]. E, F, R. acuta [E, stylet A; F, stylet B (both from the holotype)]. G, R. falcata (from a specimen from Marseilles). Scale bars = 20 Mm.

Figure 8. Stylets of the representatives of the steueri-group. A, R. cincta (from the holotype). B, R. gallica (from a specimen from Marseilles). C, R. martensi sp. nov. (from the holotype). D, R. palula (from the lectotype). E, R. reticulata (from the holotype). F. R. steueri (from the neotype). Stylet A is indicated by an A, stylet B by a B. For each stylet plate 1 is indicated by a 1, plate 2 by a 2. Arrows: see text. Scale bar = 25 Mm.