Parabaissaeshna ejerslevense, Bechly & Rasmussen, 2019

Bechly, Günter & Rasmussen, Jan Audun, 2019, A new genus of hawker dragonfly (Odonata: Anisoptera: Aeshnidae) from the Early Eocene Fur Formation of Denmark, Zootaxa 4550 (1), pp. 123-128 : 124-125

Parabaissaeshna ejerslevense sp. nov.

Figures 1–2

Holotype. Isolated complete forewing of a dragonfly with collection no. MGUH 33076 , deposited in the type collection of the Natural History Museum of Denmark, University of Copenhagen in Copenhagen ( Denmark). The specimen was discovered by the amateur fossil collectors Frank Pedersen and Viggo Pedersen, Mors, and declared as Danekrae fossil trove DK 792.

Type locality and horizon. Mo-clay quarry near the village Ejerslev (56.93° N, 8.91° E), northern island of Mors, western Limfjord area, N. Jutland, Denmark. Calcareous concretion approximately 2 m above Ash layer - 11 in the diatomites of the upper part of the Knudeklint Member, Fur Formation.

Stratigraphy. Dinoflagellate Zone 7 (corresponding to the acme of Deflandrea oesbisfeldensis ) of Heilmann- Clausen (1985), earliest Ypresian, Early Eocene, Paleogene, ca. 56.0-54.5 million years. The Early Eocene age of the Fur Formation was recently established due to the presence of the Paleocene-Eocene Thermal Maximum (PETM) in the Stolleklint clay of the Ølst Formation, which is placed stratigraphically immediately below the Fur Formation ( Heilmann-Clausen & Schmitz 2000; Schoon et al. 2013).

Etymology. A noun in the genitive case, named after the place of origin.

Diagnosis. Same as genus since monotypic.

Description of holotype ( Figures 1–2 ). Well-preserved and complete isolated forewing of a hawker dragonfly of unknown sex. Total length 45.0 mm, max. width 10.4 mm. 4 secondary antenodal crossveins between the primary antenodal crossveins Ax1 and Ax2; 22 and 18 non-aligned secondary antenodal crossveins present distal of Ax 2 in both rows respectively. Space between RA and RP basal of subnodus regularly crossed by 18 antesubnodal crossveins (no cordulegastrid gap of antesubnodals near subnodus). Nodus at 48.6% of wing length; nodal veinlet short and perpendicular; subnodal veinlet oblique. About 14 postnodal crossveins non-aligned with the 19 postsubnodal crossveins beneath them; no ‘libellulid gap’ of postsubnodal crossveins near subnodus. Pterostigma elongate, elongate (covering 6 cells), with oblique sides and broadened margins; oblique and strong stigmal brace vein aligned with anterior margin of pterostigma; about six crossveins between C and RA distal of pterostigma. Primary IR1 not developed; secondary IR1 originating beneath middle of pterostigma with 3 rows of cells between it and RP1, and three rows of cells between it and RP2; RP1 and RP2 basally parallel (2 rows of cells between them) and distally divergent with 3-9 rows of cells between them; RP2 originates at subnodus; RP2 undulating; only one lestine oblique vein between RP2 and IR2, a single cell distal of subnodus. IR2 originating on RP1/2, and not forked; space between RP2 and IR2 distally widened with 2-7 (mostly four) rows of cells between them. Rspl well defined, parallel to IR2 with two rows of cells between them; about 5 intercalary veins originating from Rspl. Midfork six cells distal of triangle; 13 antefurcal crossveins between RP and MA. RP3/4 and MA weakly undulate and parallel, with two rows of cells between them distally; no bulged ‘aeshnid bulla’ between MA and RP3/4. Posttrigonal area between MA and MP with two rows of cells near the triangle; trigonal planate well defined, originating at a slight kink on the distal side (MAb) of triangle; Mspl well defined, parallel to MA, with two rows of cells between them. Space between MP and CuA narrow; MP and CuA reaching far beyond level of nodus. CuA with 7-8 posterior branches; cubital field max. 5 cells in width. Anal field with two rows of cells. Arculus complete (closed) and broken (kinked), situated midway between Ax1 and Ax2. Hypertriangle long and narrow, divided by 4 crossveins. Discoidal triangle elongate and divided into seven cells. Subtriangle divided into 2 cells. Between CuP-crossing (= ‘anal crossing’) and basal subdiscoidal vein there are two crossveins. Basal space free. Wing hyaline without trace of color pattern, except for the dark pterostigma.

Figures

FIGURE 1. Photograph of holotype no. MGUH 33076 of Parabaissaeshna ejerslevense gen. et sp. nov. Scale bar = 10 mm.

FIGURE 2. Drawing of holotype no. MGUH 33076 of Parabaissaeshna ejerslevense gen. et sp. nov. Scale bar = 10 mm.