Palaeochrysa greenwalti, Jepson & Makarkin, 2023

Palaeochrysa greenwalti sp. nov.

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Fig. 3 View FIGURE 3

Type material. Holotype USNM PAL 622159 , deposited in USNM. One nearly complete forewing, one incomplete forewing, and one incomplete hind wing .

Type locality and horizon. Middle Fork of the Flathead River , between Paola and Stanton Creeks approximately 17 miles south of West Glacier; the Coal Creek Member of the Kishenehn Formation, north-western Montana, U.S.A. Middle Eocene (Lutetian) .

Etymology. From the surname of Dale E. Greenwalt, in recognition of his work on the Kishenehn Formation.

Diagnosis. Similar to Palaeochrysa stricta differing from it by smaller size [forewing length ca. 11.2 mm in P. greenwalti sp. nov.; 15.5 mm in P. stricta ] and proximal-most crossvein of inner gradate series in hind wing (after RP5) shifted posteriorly, so that it terminates on Psm [terminates on RP5 far anterior to Psm in P. stricta ]; it differs from P. minor sp. nov. by larger size and wider forewing [length/width ratio ca. 2.95 in P. greenwalti sp. nov.; ca. 3.17 in P. minor sp. nov.].

Description. Forewing ca. 11.2 mm long, 3.8 mm wide. Costal space moderately broad. Subcostal veinlets simple, relatively closely spaced. Sc long (its termination not discernible). Subcostal space narrow, crossveins not detected. RA terminated at margin slightly proximad wing apex. RA space broad, narrowed distad, with 14 regularly spaced crossveins. RP with 13 pectinate branches. RP1 to RP5 terminated at Psm; two distal branches simple; forking of most other branches unclear, at least two in distal portion forked once in one of forewings. Psm straight, only slightly zigzagged. M poorly preserved proximally, forked slightly distad origin of RP. im incompletely preserved (its shape probably similar to that of other species of the genus: narrow, elongate). Presumable MA forked once distad Psc; presumable MP forked at Psc. Crossvein 2m-cu long, located in proximal part of im. Psc straight, slightly zigzagged only distally. CuA presumably with three branches. CuP forked, with both branches widely spaced. 1A partially preserved. Two gradate series of crossveins nearly parallel; inner series forming distinct angle with Psm at RP5, with six preserved crossveins after RP5 (probably eight in life); outer series continuing Psc, with nine crossveins after RP5.

Hind wing 9.5 mm long as preserved, 2.9 mm wide as preserved. Costal space not preserved. Sc preserved only basally. RA not preserved in distal part. RA with 10 preserved crossveins. RP with 11 preserved pectinate branches (probably 12 in life). RP1 (presumably) to RP5 terminating at Psm; two distal branches simple; other branches forked once. Psm straight, almost not zigzagged. Proximal part of M not preserved; presumable MA forked distad Psc; presumable MP forked at Psc. Psc straight, zigzagged only in distal part. Presumable CuA with two preserved branches. Anal veins not preserved. Two gradate series of crossveins: inner series convex, forming distinct angle with Psm at RP5, with seven preserved crossveins before RP5 (eight in life); outer series continuing Psc, with six preserved crossveins before RP5 (eight in life).

Remarks. The apex of the forewing of P. greenwalti sp. nov. appears more rounded than in the other species. No body parts are preserved and some parts of the forewing venation and the basal part of the hind wing are difficult to interpret.