Triassologus Riek, 1976

Béthoux, Olivier & Anderson, John M., 2023, New light shed on Triadophlebiomorpha wing morphology and systematics (Insecta: Odonata), Geodiversitas 45 (17), pp. 479-496 : 486-488

Genus Triassologus Riek, 1976

Triassologus Riek, 1976: 793 . — Type species: see below.

Iverya Béthoux & Beattie, 2010: 689 — Type species: Iverya aveyri Béthoux & Beattie, 2010 , n. syn.

TYPE SPECIES. — Triassologus biseriatus Riek, 1976 by original designation.

OTHER SPECIES. — Triassologus aveyri ( Béthoux & Beattie, 2010) , n. comb.

EMENDED DIAGNOSIS. — Hindwing broader than forewing (1.3 broader opposite nodus); area between anterior wing margin (or ScA) and ScP very broad in forewing, moderately broad in hindwing; area between anterior wing margin and RA very narrow opposite the third quarter of wing length, before widening again (as opposed to tapering, or broadening, regularly from the nodus to the apex; uncertain in Triassologus aveyri n. comb.); nodal and sub-nodal cross-veins short, moderately strong, sub-aligned, oblique (condition unknown in Triassologus aveyri n. comb.); RP1/RP2 fork in a position more distal than that of the point of origin of the first I- in the RP3+4 area; first I- in the Irp 1 -rp 2 -RP2 area seemingly originating from RP2 (i.e. RP2 pseudo-forked; large blue arrows on Fig. 4B-D, F; unknown in Triassologus aveyri n. comb.); point of origin of the first I- in the RP3+4 area basal to the RP1/RP2 fork; RP3+4 very long, parallel to the posterior wing margin for some distance (unknown in Triassologus aveyri n. comb.); pons moderately long; RP/MA fork opposite that of MP/Cu+AA; at least in the basal part of the CuA-CuP area, I- rectilinear and seemingly originating from CuA (possibly as convex elements quickly turning concave; large white arrows on Fig. 6 ), genuine CuA branches zigzagging and seemingly originating from cross-venation (i.e. as an I+; large green arrows on Fig. 6 ; and see small green arrows on Figs 4D, 5B); CuP reaching GEODIVERSITAS • 2023 • 45 (17)

487 the posterior wing margin opposite the nodus or slightly distal to it; CuP and AA posteriorly pectinate, with a curved and sigmoid course, respectively; area between AA (or Cu+AA, or MP+Cu+AA) and the posterior wing margin, opposite and basal to the pons, narrow (i.e. not forming a lobe).

REMARKS

It will be shown below that ‘ Reisia ’ rieki Deregnaucourt, Wappler, Anderson and Béthoux, 2017 is a junior synonym of Triassologus biseriatus Riek, 1976 . This could imply that Triassologus is a junior synonym of Reisia . However, new data derived from additional material of Triassologus biseriatus (see below) and on Reisia spp. (see above) allows to convincingly differentiate the two genera, including the width of the area between the anterior wing margin (or ScA) and ScP, and the particular organisation of I- and CuA branches in the CuA-CuP area, among others.

The more complete data on Triassologus biseriatus (see below) led us to compare it with the Australian Triassic species ‘ Iveryia ’ aveyri Béthoux & Beattie, 2010 (type species of the genus Iverya Béthoux & Beattie, 2010 ). Indeed, as far as comparison can be made, the two species do not display major differences other than size-related ones, such has the overall number of vein branches (assuming that the only known specimen of ‘ Iverya ’ aveyri is a forewing, it is about 1.4 times larger than in that of Triassologus biseriatus ). We therefore propose to newly assign ‘ Iverya ’ aveyri to Triassologus , further exemplifying similarities between South African and Australian Triassic insect faunas ( Tierney et al. 2020; Béthoux & Anderson 2021).

Bechly (1997) considered that RP2 is branched in Triassologus biseriatus . However, bearing in mind the propensity of intercalary veins to acquire a main vein habitus points to Odonata in general and Triadophlebiomorpha in particular, an alternative option, favoured herein, is that the apparent anterior branch of RP2 (large blue arrow on Fig. 4B-D, F) instead is the first I- in the area between Irp 1 -rp 2 and RP2.

Figures

FIG. 6. — Detail of the organisation of CuA branches and of I- in the basal portion of the CuA-CuP area in Triassologus spp. (large green arrows, CuA branches; large white arrows, Icua): A, Triassologus biseriatus Riek, 1976, specimen PRE/F/5118b (wing in dorsal aspect), flipped horizontally, location as shown on Fig.4E; B, Triassologus aveyri (Béthoux & Beatie,2010),n.comb.,holotype, specimen AM F.132815. Scale bars: 5 mm.