Cordulibellula inopinata, Sroka & Howells & Nel, 2023

Sroka, Steven D., Howells, Thomas F. & Nel, André, 2023, A new transitional “ libelluloid ” family of odonates with Mesozoic affinities in the Eocene Green River Formation of Utah, USA, Acta Palaeontologica Polonica 68 (2), pp. 337-342 : 338-340

Cordulibellula inopinata sp. nov.

Figs. 1 , 2 .

Zoobank LSID: urn:lsid:zoobank.org:act:B664998B-1919-451F-8BF3-80AF942020B5

Etymology: From Latin inopinata , unexpected; referring to the unexpected find of a “relict” “libelluloid” related to Mesozoic taxa in the middle Eocene.

Type material: Holotype FHPR 11611, part and counterpart of an isolated hind wing, partly folded and deformed.

Type locality: Lake Uinta , near Bonanza, Utah, USA .

Type horizon: Upper Parachute Creek Member, Green River Formation; middle Eocene.

Diagnosis.—Hind wing characters only. Straight gaff (= basal CuA before its branching); CuAa with at least three posterior branches; an obliquely elongate anal loop subdivided into one large and two smaller cells; MP and MAa clearly undulating; a well-defined Rspl; a zigzagged Mspl.

Description.—Preserved part of wing 29.2 mm long, ca. 6.0 mm wide, estimated length of wing 32.0 mm; distance between nodus (N) and pterostigma (Pt) 13.6 mm between pterostigma and wing apex 2.8 mm; pterostigma 3.3 mm long, 0.8 mm wide, parallel sided (distal side not more oblique than basal side), covering two long cells; pterostig- mal brace aligned with basal side and weakly oblique; 11 postnodal crossveins, not aligned with the eight postsubnodal crossveins; an important “libellulid” gap in basal part of postsubnodal space; “cordulegastrid” gap present; five visible antenodal crossveins of first and second rows nearly aligned, probably nine originally, primary antenodals not preserved; arculus only partly preserved (posterior part); discoidal triangle free, isosceles, with base located close to arculus, separated by less than 1/2 length of arculus, basal side of discoidal triangle (t) 1.7 mm long, anterior side 2.8 mm long, distal side (Mab) 2.8 mm long; hypertriangle likely with two crossveins, with MA distinctly curved; subdiscoidal space free, distinctly closed by an oblique PsA incompletely preserved; only CuP in submedian space; median space free; anal loop (al) transversely elongate, 4.8 mm long, max. 1.0 mm wide, narrow obliquely elongate, with a midrib and divided into one large and two smaller cells; basal CuA before its branching long but straight; CuAa with at least three posterior branches, probably more; MP basally weakly zigzagged and distally undulated; MAa distally undulated too; posdiscoidal area rather broad, with two rows of cells basally near the discoidal triangle and a zigzagged Mspl, one row of cells between MAa and Mspl; RP3/4 poorly preserved; IR2 weakly zigzagged, parallel with RP 2 in its main part, but diverging distally; two Bqs crossveins; base of RP2 aligned with subnodus; lestid oblique crossvein one cell distad subnodus; one row of cells between RP1 and RP2 up to 3.5 mm basad pterostigma; a strongly zigzagged IR1; a well-defined Rspl weakly curved anteriorly, with one row of cells between it and IR2.

Stratigraphic and geographic range.—Upper Parachute Creek Member, Green River Formation, middle Eocene; Lake Uinta.

Figures

Fig. 1.Anisopteran dragonfly Cordulibellula inopinata gen. et sp. nov. from Lake Uinta, Utah, USA, Eocene,holotype FHPR 11611, part (A1), counterpart (A2), detail of wing base (A3). Abbreviations: a.l., anal loop; N, nodus; t, discoidal triangle.

Fig. 2.Anisopteran dragonfly Cordulibellula inopinata gen.et sp. nov.from Lake Uinta, Utah, USA, Eocene, holotype FHPR 11611, reconstruction of wing base (A1), detail of wing apex (A2). Abbreviations: a.l., anal loop; N, nodus; Pt, pterostigma; t, discoidal triangle.