Whetwhetaksidae 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 : 110

Whetwhetaksidae Archibald & Cannings , new family

Figs. 66–70 .

Diagnosis. Most easily separated from all other Cephalozygoptera and Zygoptera families by 1, distinctively long pterostigma: length about ten times width (roughly, where known), nodus to base of pterostigma 55–60% of nodus to apex; and from all Cephalozygoptera and all Zygoptera except the extant Heliocharis amazona (Dicteriadidae) and some Paleogene Euphaeidae by 2, arculus just distal to Ax1, closer to it than to Ax2. Differs further from Sieblosiidae by: 3, oblique vein O absent [present]; 4, nodal, subnodal crossveins oblique [usually nearly vertical, sometimes slightly oblique or reversed obliquity]; 5, base of RP2 close to nodus [more distal]; 6, CuA terminates at margin over half wing length [notably shorter, longest Parastenolestes oligocenicus Nel & Paicheler , under half wing length]; 7, MA close to, subparallel with RP3-4 to margin [subparallel with MP]; 8, MA, MP diverge to margin [remain close]; 9, MP, CuA remain subparallel to margin [widely diverge]; 10, base to nodus about 40% wing length, minimum about 38% [maximum about 35% where measurable]. Differs further from Dysagrionidae by: 4 [usually like Whetwhetaksidae , but Dysagrion subnodal crossvein reverse obliquity]; 7–9, [varies], 10, [ Dysagrion packardii , about 42%, Petrolestes hendersoni , about 42%, the rest about 36–25%]; 11, origin of IR 2 in middle third between arculus, nodus [at subnodus in Dysagrioninae , but as in Whetwhetaksidae , in Petrolestinae].

Type and included genera. Whetwhetaksa .

Description. As for its only genus, see below.

Etymology. The family name is formed from that of its type and only genus, Whetwhetaksa .

Range and age. Republic localities B4131 and A0307B of the Tom Thumb Tuff Member of the Klondike Mountain Formation; latest Ypresian.

Discussion. Such an extremely long pterostigma is never found in the Zygoptera to our knowledge, but is matched by some Petaluridae (Anisoptera) .

The position of the arculus closer to, immediately distal to Ax1 is remarkable. This condition is found in the Anisozygoptera and Anisoptera , but in the Zygoptera only in the South American H. amazona , which otherwise differs strongly in many ways and a few Paleogene Euphaeidae (see above) which also strongly differ. In all other Zygoptera it is aligned with, slightly proximal to, or slightly to clearly distal to Ax2 ( Bechly 1996; Fleck et al. 2004).

In SR 06-01-36, the subcosta appears to cross through the nodus, which is characteristic of the Sieblosiidae (see, e.g., Nel & Fleck 2012, their Fig. 3 ). This is not present in any other specimen of Whetwhetaksa , and it could be a crossvein adventitiously positioned between the costa and nodus in this specimen and not the subcosta.

We tentatively associate the Whetwhetaksidae with the Cephalozygoptera by the many similarities of their wings (see description of the suborder, above). The wings of Whetwhetaksidae are more like those of the Cephalozygoptera than any Zygoptera , but await confirmation of this relationship by the discovery of a more complete fossil that includes the head.

Figures

FIGURE 3. Phenacolestes parallelus. A, specimen YPMIP-220974 of the Yale Peabody Museum; B, drawing from A, photograph provided by Peabody Museum personnel; C, holotype, UCM-4503 of the University of Colorado (Boulder) paleontology collections; D, drawing of C, photograph provided by University of Colorado personnel; E, UCM-4545, University of Colorado (Boulder). A–D to scale, E to scale, both scale bars 5 mm.

FIGURE 66. Whetwhetaksa millerae holotype, SR 06-01-38. A, photograph; B, drawing. Both to scale, 5 mm.

FIGURE 67. Whetwhetaksa millerae paratype 1, SR 10-36-10. A, photograph; B, drawing. Both to scale.

FIGURE 68. Whetwhetaksa millerae paratype 2, SRUI 99-98-34. A, photograph; B, drawing. Both to scale; aa, accessory antenodal crossvein.

FIGURE 69. Whetwhetaksa millerae additional material. SR 93-11-01: A, photograph; B, drawing; SR 06-01-36: C, photograph; D, drawing.All to scale, 5 mm.

FIGURE 70. Whetwhetaksa millerae, additional material. SR 10-14-19: A, photograph; B, drawing; SR 05-11-01: C, photograph; D, drawing.All to scale, 5 mm.