Palaeochrysa minor, Jepson & Makarkin, 2023

Palaeochrysa minor sp. nov.

urn:lsid:zoobank.org:act:ECE45B39-18B0-45CC-97C1-07942C4A2BC7

Fig. 4 View FIGURE 4

Type material. Holotype USNM PAL 722497 , deposited in USNM. An incomplete, crumpled specimen .

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. The Middle Eocene (Lutetian).

Etymology. From the Latin parvus , - a, - um (comparative minor ), meaning “small (smaller)”.

Diagnosis. Differs from two other species by smaller size, subcostal veinlets widely spaced [closely spaced in other species], and three branches of RP terminating on Psm [five in other species].

Description. Body very poorly preserved, details not discernible.

Forewing ca. 9.5 mm long, ca. 3.0 mm wide. Costal space relative narrow. Subcostal veinlets simple, relatively widely spaced. Distal parts of Sc, RA not preserved. Subcostal space narrow, crossveins not detected. RA space with five detected, widely spaced crossveins. RP with nine pectinate branches. RP1 to RP3 terminated at Psm; two or three distal branches simple; RP1 deeply forked at Psc and its proximal branch shallowly forked in left forewing; other branches rather shallowly onсe forked. Basal crossvein 1r-m very short, connecting anterior trace of RP and MA within im at proximal one-third length. Psm straight, only slightly zigzagged. M forked slightly distad origin of RP. im narrow, elongate (3.8 times as long as wide). Crossvein 2m-cu long, connecting im and CuA at nearly proximal one-fifth of im. Psc straight, slightly zigzagged distally. CuA probably with two simple branches. CuP deeply forked. Two intracubital crossveins; c1: c2 length ratio 0.82: 1 in right wing. A1 simple. A2 strongly arched, simple. Two gradate series of crossveins nearly parallel; inner series with six crossveins after RP3; outer series continuing Psc, with six crossveins after RP3.

Hind wing 6.8 mm long as preserved, 2.3 mm wide as preserved. Costal space very narrow. Sc preserved proximally. Subcostal space appears to be very narrow. RA long, terminating at margin probably near wing apex. RA space with eight regularly spaced crossveins. RP with nine pectinate branches. RP1 to RP3 terminated at Psm; three distal branches simple; forking of other branches mostly unknown. Psm straight, slightly zigzagged. M proximally fused with RP. Presumable MA forked distad Psc; presumable MP forked at Psc. Psc slightly zigzagged. CuA with three simple branches; probably all originating before fusion of CuA with MP. CuP, A1, A2 simple. Two nearly parallel gradate series of crossveins: inner series with four preserved crossveins after RP (probably six in life); outer series continuing Psc, with six crossveins after RP3.

Remarks. Palaeochrysa minor sp. nov. is the smallest member of the genus and has a more elongate forewing than the other species. The small size is reflected in the venation with it having only three branches of RP terminating on Psm [five in the other species of the genus].