Danowhetaksa birgitteae Simonsen, Ware & Archibald, 2022

Simonsen, Thomas J., Archibald, S. Bruce, Rasmussen, Jan A., Sylvestersen, René L., Olsen, Kent & Ware, Jessica L., 2022, Danowhetaksa gen. nov. with two species from the early Eocene Ølst Formation from Denmark, the first Palearctic Whetwhetaksidae (Odonata: Cephalozygoptera), Zootaxa 5099 (5), pp. 586-592 : 588-589

Danowhetaksa birgitteae Simonsen, Ware & Archibald , new species

Figure 1

Material. Holotype [ FUM-M-17515 ]: an isolated wing preserved in a concretion block; the part is missing the basalmost and apical-posterior portions, and the counterpart is missing the apical-most portion including the pterostigma; collected by Birgitte Munk, 1996, Fur Stolleklint; deposited in the Fur Museum.

Description. Holotype wing. Length, arculus to distal end of pterostigma: 28.0 mm; nodus to distal end of pterostigma: 20.3 mm; arculus to base of pterostigma: max 23.4 mm; nodus to base of pterostigma: max 16.2 mm; width: 9.3 mm. Pterostigma dark (damaged basally), preserved part approximately 5 mm in length, highly elongate, at least seven times longer than wide, subtends numerous cells, five crossveins detected by preservation, surely many more. Membrane with a transverse, sub-central dark fascia, slightly narrower than length of pterostigma, otherwise hyaline. Twenty-three crossveins preserved in postnodal space, 22 in postsubnodal space, only pair aligned. IR1 very poorly preserved, origin probably slightly zigzagged, seven cells distal to origin of RP2. RP2 originates seven cells distal to subnodus. IR2 originates approximately 8.5/10 distance arculus to nodus, preserved part of IR2 close to linear. RP3-4 originates approximately 4/10 distance arculus to nodus, preserved part of RP3-4 close to linear. MA linear in basal 1/3, starts zigzagging slightly about basal margin of darkened wing band, poorly preserved beyond band. MP linear from origin to terminus at wing margin, slightly curved. CuA linear from origin to terminus on wing margin, basal 2/3 subparallel to MA, then curving sharper to wing margin, terminates basal to mid-wing. MA-CuA space two cells wide where CuA starts curving away, widening to at least six cells at wing margin. CuA-A space well preserved, very broad, at least five cells wide. Quadrangle sub-trapezoid, broadest distally, approximately 1.3 times longer than wide. Anterior wing margin not preserved basal to arculus, so Ax1 not preserved. Ax2 approximately 2/10 distance arculus to nodus, just distal to anterodistal corner of quadrangle.

Diagnosis. Distinguished from D. rusti by any of: 1, RP1-2–IR2 space one cell wide, RP2–IR2 space to origin of IR1 (not preserved beyond this) [RP1-2–IR2 space becomes two cells wide ca. two cells basal origin of RP2]; 2, IR2–RP3-4 space becomes two cells wide ca. mid-way between origins of RP2, IR1 [ca. origin of IR2]; 3, seven crossveins in R1+2–IR2 space between nodus and origin of RP2 [ca. 9]. Further separated by colouration (sex unknown): narrow, dark fascia mid-wing [almost twice as wide], basally starting ca. five cells distal to nodus, includes origin of RP2, ends slightly distal to termination of CuA [anterior to R1+2 starts at nodus, posterior R1+2 just basal origin of IR2, ends on posterior margin just basal to termination of CuA, on anterior margin slightly more distal].

Deposit and age. Stolleklint clay, Ølst Formation, Stolleklint, Fur, Denmark; earliest Ypresian.

Etymology. An eponym formed from the given name of Birgitte Munk, who found and donated the holotype, recognising her contribution.

Remarks. Colouration is provided as supplementary in the diagnosis, as it is unknown if there are differences in colouration due to sexual dimorphism, variation between forewings and hind wings, or polymorphism in Whetwhetaksidae .

Although the wing base is not preserved, we estimate CuA to terminate on the margin just over half wing length.

Figures

FIGURE 1. Danowhetaksa birgitteae n. sp., holotype wing [FUM-N-17515]. A, photograph of part; B, drawing from part and counterpart. Short arrows indicate crossveins below pterostigma (see text). Scale bar is 5 mm.