Dysagrion Scudder
Creators: name: Archibald, Bruce
name: Cannings, Robert A.
name: Erickson, Robert J.
name: Bybee, Seth M.
name: Mathewes, Rolf W.
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Odonata
Dysagrionidae
Dysagrion

description: Genus Dysagrion Scudder
Figs. 4–6, 14–16.
Diagnosis (emended). Wings distinguished from those of other Dysagrionidae genera by subnodus with reverse obliquity [all others and tentative Dysagrionidae as below (where known), normal]; and from all Dysagrioninae by: from Okanopteryx, Furagrion by pterostigma long (4–7 times its width) [Okanopteryx: 2.5 times; Furagrion: 3; not from Okanagrion: 3–4; Stenodiafanus: 4; Primorilestes: 3.5–4; Phenacolestes: 5; Dysagrionites species: unknown]; with oblique brace vein joining posterior-proximal corner of pterostigma in forewing, hind wing [not present in Okanagrion, Phenacolestes (both known from fore-, hind wings), not known in Primorilestes (fore- or hind wings?); known in Furagrion, Okanoptyeryx, Stenodiafanus; wing region not preserved in Electrophenacolestes, Dysagrionites species]; costal space distal to pterostigma 1 cell wide [distinct from Primorilestes, Okanopteryx, Stenodiafanus: all 2; Okanagrion: 3–5; shared with Furagrion, Phenacolestes: 1; Electrophenacolestes, Dysagrionites species: not known]; IR2 origin between RP1-2, RP3-4, closer to RP3-4, connected to RP1-2 notably more distally than to RP3-4 [other genera: origin close to or on RP1-2 (some Okanagrion), or between RP1-2, RP3-4 as in Dysagrion (all others), but connected with RP1-2 similar level as RP3-4]; MA linear from quadrangle to zigzagged roughly mid-wing or further, linear again near, to margin [Furagrion: similar (but differs by distinct curve beyond mid-wing); Phenacolestes: very slightly zigzagged or not in mid-portion; Primorilestes, Okanagrion: not zigzagged; Okanopteryx, Stenodiafanus, Dysagrionites species: linear to mid-wing, somewhat to strongly zigzagged to margin (in portions known); MA, MP close, 1–2 cells apart at margin [distinct from Electrophenacolestes, Furagrion, Primorilestes, Okanagrion, Phenacolestes: widely separated; not clearly distinct from Okanopteryx, Stenodiafanus, difficult to be sure of identity of MA near margin by strong zigzag, probably separated by two cells; Dysagrionites species also difficult, perhaps one cell]; CuA increasingly zigzagged distal to level of nodus [distinct from Furagrion: slightly zigzagged distal to about level of origin of RP2; Phenacolestes: very slightly zigzagged in parts; Electrophenacolestes, Primorilestes, Okanagrion: linear or only very slightly zigzagged; not clearly distinct from Okanoptyeryx, Stenodiafanus: zigzagged to various degrees distal to about mid-wing]; CuA–A space 4 cells wide [separated from Furagrion: 2; Stenodiafanus: 2 (most likely, wing incomplete); Dysagrionites delinei: 3; Dysagrionites sp. A: 2; Dysagrionites sp. B: probably 3 but unclear; not separated from Phenacolestes: 4; Primorilestes: 3–6; Okanagrion: 4–7; Okanopteryx: 2–4; not distinct from Electrophenacolestes: 4 except 5 in one column]; further from Electrophenacolestes by shorter petiole; further from Primorilestes by no linear intercalary veins in CuA–A space. Postnodal, postsubnodal crossveins not aligned at least in proximal half [separated from Stenodiafanus, Okanopteryx, Primorilestes violetae, Electrophenacolestes, Furagrion: all aligned or somewhat so in proximal half; not distinct from Phenacolestes, Primorilestes madseni, Okanagrion: all not]. Separated from Valerea (tentative Dysagrioninae) by no linear supplementary sector between RP1, IR1 [Valerea: with such sector]; by one cell wide in costal space distal to pterostigma [Valerea: up to 5]. Most easily separated from other genera regarded here as possible Dysagrionidae as follows: from the Chickaloon specimen (Garrouste & Nel 2019) by CuA increasingly zigzagged from level of nodus [linear at least to well past level of origin of IR1 (distal-most portion not preserved)]; MA, MP close [widening in distal-most preserved portion]; from Thanetophilosina by proximal side of quadrangle more than half length of distal side [less than half], IR2 originates between RP1-2, RP3-4 [originates on RP1-2]; from NHMUK I.9866/I.9718 by origin of RP3-4 [distinctly closer to subnodus]; from cf. Dysagrionidae genus A, species A (Petrulevičius et al. 2008) by hyaline membrane [preserved portion infuscate except apex distal to pterostigma], by MA zigzagged mid-wing, CuA zigzagged distally [both linear to margin].
Discussion. Dysagrion fredericii was designated the type species of Dysagrion by Scudder (1878). His diagnosis of the genus distinguished it from Philogenia Selys, a genus currently in need of revision (Garrison et al. 2010). Philogenia had been placed in the polyphyletic Megapodagrionidae, which was recently divided into several families (Dijkstra et al. 2014), including the Philogeniidae, where it now resides. We, therefore, provide an emended diagnosis of Dysagrion, above.
An oblique brace vein between RA and RP1 at the posterior-proximal corner of pterostigma is seen in the fore- and hind wings of D. pruettae (Figs. 17, 18), and in the wings of D. lakesii (Fig. 5, slightly, but distinctly oblique), D. fredericii (see Scudder 1890 plate 6 Fig. 9), D. packardii (a portion preserved, but distinct: Fig. 4, redrawn from the original by Scudder 1890 plate 6 Fig. 3).
The subnodus appears to be of reverse obliquity in one specimen of Okanagrion hobani, paratype 1, however, given that all other of its numerous specimens have normal obliquity, we consider this adventitious in this individual.
description: Published as part of Archibald, Bruce, Cannings, Robert A., Erickson, Robert J., Bybee, Seth M. & Mathewes, Rolf W., 2021, The Cephalozygoptera, a new, extinct suborder of Odonata with new taxa from the early Eocene Okanagan Highlands, western North America, pp. 1-133 in Zootaxa 4934 (1) on pages 35-37, DOI: 10.11646/zootaxa.4934.1.1, http://zenodo.org/record/4558796