Triassologus biseriatus 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 : 488-490

Triassologus biseriatus Riek, 1976

(Figs 4-6A)

Triassologus biseriatus Riek, 1976: 793 , text-fig. 1, pl. 1, fig. 5. — Bechly 1997: 56.

Reisia rieki Deregnaucourt, Wappler, Anderson & Béthoux, 2017: 615 , figs 1-2, n. syn.

EXAMINED MATERIAL. — Holotype, specimen BP/2/20948 (left wing in ventral aspect; Fig. 4A, B); and specimens PRE/F/5118 (Fig. 4D, E) and PRE/F/10125 ( Fig. 5B, C ) (all specimens, Anderson collection, Evolutionary Studies Institute , University of the Witwatersrand, Johannesburg, South Africa).

TYPE LOCALITY AND STRATIGRAPHY. — The holotype and the specimen PRE/F/10125 were found at the ‘ Birds River’ locality (locality code Bir 111; see Anderson & Anderson 1984); material described by Deregnaucourt et al. (2017), Kapokkraal and Aasvoëlberg localities (Kap 111 and Aas 411, respectively); and specimen PRE/F/5118, Hlatimbe Valley (Hla 213); all South Africa; Molteno Formation; lower Carnian , Upper Triassic ( Anderson et al. 1998).

EMENDED DIAGNOSIS. — Maximum width about 17 mm in forewing and about 19.5 mm in hindwing (about 24 mm in Triassologus aveyri n. comb., known from a putative forewing), forewing length about 110 mm.

SPECIMEN DESCRIPTIONS

Specimen PRE/F/5118 (Figs 4D, E, 6A)

Adpression preserving a left wing in dorsal (PRE/F/5118b; wing basal and median parts; extreme base, most of posterior area, and apical area missing) and ventral (PRE/F/5118a; about the first wing third, with portion of posterior wing margin missing opposite the pons) aspects; preserved length 84.5 mm, estimated total length about 110 mm; preserved maximum width 13.6 mm, estimated total maximum width about 16.0 mm; petiole 3.5 mm wide; area between anterior wing margin broad (maximum width 2.9 mm); MA 1.0 mm long between its origin (from RP+MA) to its point of connection with the pons; distal to the pons and basal to the nodus, RA, RP and MA running very close to each other but distinct; nodus located 33.7 mm from wing base; nodal and sub-nodal cross-veins short, moderately strong, sub-aligned, oblique; RP1+2/ RP3+4 fork located shortly after sub-nodal cross-vein; RP1+2 19.3 mm long; first I- between Irp 1 -rp 2 and RP2 seemingly emerging from RP2; first I- in the area between RP3+4 and MA originating 13.6 mm distal to the RP1+2/RP3+4 fork; pons oblique, 2.5 mm long; MP/Cu+AA fork opposite that of RP/MA; MP without obvious preserved branch; Cu+AA 2.8 mm long, Cu 1.6 mm long; in CuA-CuP area, the first 2 I- rectilinear and seemingly originating from CuA, the third I- originating as convex element shortly turning concave (possibly fused with a CuA branch at its origin); CuA branches zigzagging and seemingly originating from cross-venation; CuP and AA posteriorly pectinate; CuP curved, with 6 branches preserved (probably 7 in total), with intercalary veins between them; AA sigmoidal, with a maximum of 3 cells between it and the posterior wing margin; posterior wing margin forming a sharp angle opposite the RA/RP+MA fork.

Figures

FIG. 5. — Triassologus biseriatus Riek, 1976: A, reconstruction of forewing morphology, location as shown on Fig. 4F; B, C, specimen PRE/F/10125a,left hindwing;B, drawing of venation (small green arrows indicating the termination of CuA branches); C, photograph (light-mirrored). Scale bar: 10 mm.