LIBELLULIDAE Leach, 1815

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 : 10-13

Family LIBELLULIDAE Leach, 1815 (stem group representative?)

Genus and species undetermined

Figures 7–8

Material. Specimen PE 2001/5195- LS (incomplete hind wing with only anterior half preserved), stored at the State Collection of Natural History of Rhineland-Palatinate.

Description. Hind wing, hyaline; length of preserved part 28.0 mm; width 7.0 mm; distance from base to arculus 4.0 mm, from arculus to nodus 9.0 mm, from nodus to pterostigma 13.6 mm; pterostigma incomplete but rather elongate; pterostigmal brace weak and not aligned with basal side of pterostigma; Ax1, Ax2, and first secondary antenodal of same shape with a membrane between them, C, ScP, and RA; two more distal antenodals complete but without membrane, last antenodal apparently incomplete, only present between ScP and RA; arculus midway between Ax1 and Ax2; sectors of arculus not stalked but joined at base; four antensubnodal crossveins, the last one being distal of base of IR2; hypertriangle and discoidal triangle free; PsA not oblique and weak; eight postnodal crossveins, not aligned with the postsubnodals, the two basal postsubnodals absent; no ‘libellulid oblique crossvein’; oblique crossvein ‘O’ two cells distal of subnodus ( Figures 7–8 ).

Remarks. This hind wing is attributable to the clade Libellulida Bechly, 1996, because of the following characters: hind wing discoidal triangle recessed to the level of the arculus; the first secondary crossvein has a membrane between it, C, ScP, and RA, as for the two primary antenodal crossveins Ax1 and Ax2. The absence of a ‘libellulid oblique crossvein’ between RP1 and RP2 excludes affinities with the Urothemistidae Lieftinck, 1954 . But even if the two more distal secondary antenodals are complete (alignments of the antenodals of first row with those of second row), but they lack the membrane of the three more basal antenodals, and the sectors of arculus are not stalked but only joined at their base, which are symplesiomorphies of the Libellulidae . Even if they share the character ‘sectors of arculus not stalked but basally joined’, our new fossil does not fit well in the Eocene family Urolibellulidae , belonging to the stem Libellulida, because the new fossil has its third antenodal crossvein identical to Ax1 and Ax2, which is not the case in this last family (Zeiri et al., 2015; Nel, 2020). Also, the hind wing vein PsA of the new fossil is not oblique as in the extant Libellulidae , but also different from that in the Urolibellulidae .

Thus, despite its incompleteness, that forbids us to name it, this new fossil probably belongs to the stem group of the Libellulidae .

Several representatives of the crown Libellulidae are recorded from the Oligocene of Europe (Nel and Paicheler, 1993; Nel et al., 1995, 1997, 2005), and the oldest record of the family is from the Late Cretaceous (Fleck et al., 1999). Nevertheless, the clade Libellulida is nearly unrecorded from the Paleocene and the Eocene, with only one fossil found in the earliest Eocene amber of France (Fleck et al., 2000). Thus, the present fossil is of great interest because it shows that representatives of the stem group of the Libellulidae were still present in the Late Oligocene.

Figures

FIGURE 7. Probably a stem-Libellulidae, PE 2001/5195-LS, hind wing. Scale bar is 10 mm.

FIGURE 8. Probably a stem-Libellulidae, PE 2001/5195-LS, interpretative drawing of hind wing. Scale bar is 10 mm.