Epiaeschna wisseri, Nel & Poschmann & Wedmann, 2020

Nel, André, Poschmann, Markus J. & Wedmann, Sonja, 2020, New dragonflies and damselflies (Odonata) from the late Oligocene of Enspel (Rhineland-Palatinate, SW Germany), Palaeontologia Electronica (a 59) 23 (3), pp. 1-24 : 8-10

Epiaeschna wisseri sp. nov.

Figures 5–6

zoobank.org/ 5EE44E2C-34D4-407B-BAAD-711D7093E69E

Type material. Holotype PE 2000 /5355- LS a, b (part and counterpart of a nearly complete hind wing, parts of basal fourth of wing missing), stored at the State Collection of Natural History of Rhineland-Palatinate.

Additional material. PE 1997/6211- LS a, b (part and counterpart of basal two-third of a hind wing), stored at the State Collection of Natural History of Rhineland-Palatinate.

Diagnosis. Hind wing characters only. Wing darkened; fork of IR2 far from pterostigma; base of IR1 opposite base of pterostigma; pterostigma covering four cells, 18 postnodals; area between Rspl and IR2 with three rows of cells.

Etymology. Named for Dieter Wisser, mayor of Enspel, for his continuous support of the excavations.

Description. Holotype PE 2000 /5355-LS a ( Figures 5.1 , 6.1 ): Hind wing darkened, 58.1 mm long, 16.9 mm wide, ratio length/width 3.4; distance between base and arculus 5.4 mm, between arculus and nodus 18.0 mm, between nodus and pterostigma 23.0 mm, between pterostigma and apex 7.0 mm; pterostigma 5.3 mm long, 0.8 mm wide, covering four cells; pterostigmal brace present, distinctly oblique, and aligned with basal margin of pterostigma; primary antenodal crossveins not preserved, 11 secondary crossveins visible; 18 postnodal crossveins not aligned with 17 postsubnodals; median space free; CuP not visible; RP and MA meeting at their base in arculus; posterior part of arculus not aligned with anterior part; hypertriangle crossed by three veins, rather short, 7.3 mm long, 0.9 mm wide; discoidal triangle elongate but rather broad, 6.9 mm long, 1.1 mm wide, crossed by three transverse veins; trigonal planate not preserved; Mspl partly preserved, weakly zigzagged, without strong concave bend, and with three rows of cells between it and MAa; MAa and RP3/4 parallel and MAa with no concave bend before wing margin, two rows of cells between MA and RP3/ 4 in distal end; base of RP2 aligned with subnodus; oblique vein ‘O’ one cell distal of base of RP2; distal fork of IR2 symmetrical, 6.1 mm basal of level of pterostigma, with 4–5 rows of cells in area between its branches; RP2 parallel with anterior branch of IR2, making a distinct curve; base of IR1 one cell distal of pterostigmal brace; Rspl straight, with three rows of cells between it and IR2; anal loop only partly visible; CuA poorly preserved, probably with 5–6 posterior branches and 6–7 rows of cells between it and posterior wing margin.

Additional specimen PE 1997/6211-LS a ( Figures 5.2 , 6.2 ): Hind wing, apparently hyaline, 13.6 mm wide, preserved part 28.0 mm long; distance between base and arculus 4.2 mm, between arculus and nodus 12.8 mm, pterostigma not preserved; median space free; RP and MA meeting at their base in arculus; posterior part of arculus not aligned with anterior part; hypertriangle crossed; discoidal triangle elongate but rather broad, crossed by three transverse veins; trigonal planate weak; Mspl weakly curved, with two rows of cells between it and MAa; MAa and RP3/4 parallel and MAa with no concave bend before wing margin, two rows of cells between MA and RP3/ 4 in distal end; base of RP2 aligned with subnodus; oblique vein ‘O’ one cell distal of base of RP2; distal fork of IR2 not preserved; RP2 parallel with IR2; Rspl straight, with two rows of cells between it and IR2;

PALAEO- ELECTRONICA.ORG anal loop with two rows of cells; CuA with six posterior branches and seven rows of cells between it and posterior wing margin.

Remarks. Specimen PE 2000 /5355-LS ( Figures 5.1 , 6.1 ; a hind wing because of the broad cubito-anal area) is extremely similar to those of the Oligocene-Miocene hawker dragonflies of Eurasia described or revised in Nel and Petrulevičius (2010) and Li et al. (2011), and attributed to the genus Epiaeschna . Epiaeschna heros differs from all fossil species in the shorter and less oblique pterostigmal brace and narrower area between IR2 and Rspl with only two rows of cells (Garrison et al., 2006). Epiaeschna wisseri sp. nov. differs from Epiaeschna pseudoheros in the base of IR1 being opposite to the base of the pterostigma instead of being opposite to its middle, the pterostigma covering four cells instead of five, and the presence of only 18 postnodals instead of 20. The pterostigma of Epiaeschna stauropolitana covers seven cells, and its area between Rspl and IR2 has two rows of cells instead of three as in Epiaeschna wisseri sp. nov. Epiaeschna magnifica also has a pterostigma covering 7–8 cells, and its base of IR1 is well basal of the pterostigmal brace. Epiaeschna gossi has much more postnodals than Epiaeschna wisseri sp. nov. and a very long and oblique pterostigmal brace. Epiaeschna matutina has 21 postnodals in a slightly shorter wing (55.6 mm long, instead of 58.1 mm in Epiaeschna wisseri sp. nov.). Otherwise, the

NEL, POSCHMANN, & WEDMANN: ODONATA FROM ENSPEL venations of E. matutina and Epiaeschna wisseri sp. nov. are very similar, even in their darkened wings and the ratios wing length/wing width (Li et al., 2011). The most significant difference is in the position of the fork of IR2, being farther from the pterostigma in Epiaeschna wisseri sp. nov. than in E. matutina [viz. 6.1 mm basal of level of base of pterostigma in Epiaeschna wisseri sp. nov., while it is 5.1 mm in E. matutina , that is ratio (wing length/ distance between Pt and fork of IR2) = 9.5 in Epiaeschna wisseri sp. nov. vs. 10.9 in E. matutina ].

Specimen PE 1997/6211-LS ( Figures 5.2 , 6.2 ) is also a hind wing (female, because of the absence of anal angle and triangle), smaller than holotype PE 2000 /5355-LS and with a wing membrane apparently hyaline. But these differences are compatible with intraspecific variations and taphonomic biases. Despite the lack of information on the fork of IR2, the venation of the preserved part fits well with that of the extant and fossil Epiaeschna spp. , especially in the narrow anal loop with two rows of cells (see Garrison et al., 2006: fig. 247). Thus, we tentatively attribute it to Epiaeschna wisseri sp. nov., but with some doubt, so that we do not consider it as a paratype.

Figures

FIGURE 5. Epiaeschna wisseri sp. nov. 1, holotype, PE 2000/5355-LS a; 2, putative specimen PE 1997/6211-LS a, hind wing. Scale bars are 10 mm.

FIGURE 6. Epiaeschna wisseri sp. nov., interpretative drawings of hind wings. 1, holotype, PE 2000/5355-LS a; 2, putative conspecific specimen, PE 1997/6211-LS a, female hind wing. Scale bars are 10 mm.