Okanagrion lochmum Archibald & Cannings, 2021

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, Zootaxa 4934 (1), pp. 1-133 : 50

Okanagrion lochmum Archibald & Cannings , new species

Fig. 23 .

Diagnosis. Wings separated from those of O. worleyae by shape: posterior margin more deeply curved ( O. angustum not known by preservation); from O. beardi , O. dorrellae by MP, CuA sub-parallel at terminus on posterior margin [ O. beardi : distinctly wider, O. dorrellae : widening, but less distinctly as CuA zigzagged distally ( O. angustum , not known); from O. hobani by RP2, IR2, RP3-4, MA, MP not as strongly curved at margin (veins anterior to these not preserved at margin); from O. hobani by main veins less deeply curved near margin; from O. threadgillae by IR2–RP3-4 space at wing margin about half width as in O. threadgillae ; from O. angustum , O. dorrellae by width measured two cells proximal to origin of RP2 perpendicular to apical margin [ O. angustum , O. dorrellae : 75% width of O. lochmum ]; from O. dorrellae by MP linear to margin [ O. dorrellae : zigzagged near margin]; from O. angustum , O. beardi by IR2 origin between RP1-2, RP3-4 [ O. angustum , O. beardi : origin on RP1-2]; from O. threadgillae , O. beardi , O. dorrellae , O. hobani , O. liquetoalatum , O. worleyae by cells denser in apical wing: RA–RP1 space becomes two cells wide just over seven cells proximal to pterostigma [ O. threadgillae , O. beardi , O. dorrellae : about three cells proximal to it; O. hobani : about two to four; O. liquetoalatum : one; O. worleyae four]; RA–RP1 space three cells wide from about one cell proximal to pterostigma [ O. threadgillae , O. hobani , O. liquetoalatum , O. worleyae : at or one cell from apical corner of pterostigma; O. beardi : two–three cells apical to pterostigma; O. angustum , O. dorrellae : not known]; RA–RP1 space becomes four/five cells wide at distal corner of pterostigma [ O. hobani : from about half distance from pterostigma to margin; O. beardi : becomes maximum four wide about four–five cells distal to pterostigma; O. liquetoalatum : five cells wide over half distance from pterostigma to margin; O. worleyae : maximum four wide from about four or more cells distal to pterostigma; O. angustum , O. dorrellae : not known by preservation].

Further separated by colouration (sex unknown): similar to that of O. beardi , and differing from other species of the genus as in their diagnoses.

Type material. Holotype: RBCM 11799.001 ( Fig. 23 ), collected at the McAbee Hoodoo Face beds by John Leahy, date unknown: a mostly complete wing missing the apical-most portion and small damage proximally; housed in the Royal British Columbia Museum collections.

Description. Holotype, RBCM 11799.001, hind wing. Shape generalised for Okanagrion hind wing, i.e., anterior margin nodus to pterostigma rather straight, posterior margin deeply curved; length arculus to base of pterostigma: 20.4 mm; nodus to base of pterostigma: 15.4 mm; nodus estimated at about 28% wing length; maximum width 8.5 mm; colouration as in diagnosis; pterostigma anterior, posterior margins oblique (anterior margin more), three times longer than wide, subtends 5.5 cells; no oblique brace vein; crossveins in postnodal, postsubnodal spaces not aligned; maximum four cells wide distal to pterostigma in costal space (but region damaged); RA–RP1 space maximum five cells wide in preserved portion; IR1 origin six cells distal to origin of RP2; RP2 origin five cells distal to origin of IR2; IR2 origin close to subnodus, immediately proximal to it; RP3-4 origin in distal part of middle third between arculus, nodus; arculus at Ax2; Ax0 not detected; no crossvein O; MA linear (very slight, short zigzag); MP linear, hardly curved from quadrangle to terminus about two-thirds distance from nodus to pterostigma; MP, CuA sub-parallel at terminus on posterior margin; CuA linear; CuA–A space with seven cells at widest (between levels of origins of IR1, RP2).

Etymology. The specific epithet lochmum is the Latinized neuter adjective form of the Greek Λóχμη, lóchmi, meaning thicket, referring to the denseness of the crossvenation.

Range and age. McAbee, BC, Canada; mid-Ypresian.

Figures

FIGURE 23. Okanagrion lochmum holotype, RBCM 11799.001. A, photograph; B, drawing. Both to scale, 5 mm.