Treintamilun vuelvenlucha, Petrulevičius, 2017

Petrulevičius, Julián F., 2017, First Frenguelliidae (Insecta: Odonata) from the middle Eocene of Río Pichileuf ̇, Patagonia, Argentina., Arquivos Entomolóxicos 18, pp. 367-374 : 369-370

Treintamilun vuelvenlucha sp. nov. ( Figs. 1-3 )

Diagnosis. As for the genus (see above).

Description. A complete hindwing (?) with two dark zones crossing the wing ( Figs. 1-2 ), one beneath the pterostigma and the other covering the area distal to the nodus to the height of RP2; other areas hyaline; petiole short, about 3 mm long; wing 32.6 mm long, 7.6 mm wide; petiole short and broad, 3 mm long and 1.5 mm wide; wing 32.6 mm long, 7.6 mm wide; distance between base and arculus, 4.5 mm, between arculus and nodus, 5.2 mm, between nodus and pterostigma, 16 mm, between pterostigma and apex, 2.3 mm; nodus basally recessed; pterostigma long (4.1 mm) and broad (0.9 mm), covering four and a half cells ( Fig. 3C ); pterostigmal brace reduced, anterior side of pterostigma sligthly oblique; Ax2 just distal to arculus; Ax1 1.6 mm basally; discoidal cell basally closed, broad, distinctly widened distally, anterior side, 0.7 mm long, posterior side, 0.9 mm long, basal side, 0.3 mm long, distal side, 1.3 mm long; no antesubnodal cross-veins; discoidal cell basally closed, broad, distinctly widened distally, anterior side (MA), 0.3 mm long, posterior side (cross-vein = ddcv), 1.3 mm long, basal side (cross-vein = bdcv), 0.7 mm long, distal side, 0.9 mm long; arculus short; RP get free nearer anterior side of arculus; ddcv about 80º to MA; MP + CuA with a strong angle just distal of the base of CuP; CuP curved ( Fig. 3A ); base of RP3+4 between arculus and nodus, about 2.8 mm basal to subnodus, 2.3 mm distal to arculus; base of IR2 below subnodus; base of RP2 six cells, 6 mm distal of subnodus; base of IR1 2-3 veins distal to RP2; nodal cross-vein (Cr) sub-vertical ( Fig. 3B ), 0.1 mm distal of point of fusion of ScP with costal margin; subnodus vertical; posterior bent of CP not aligned with Cr but in a slightly distal position, at the point of fusion between ScP and costal margin; 17 postnodal cross-veins between C and RA, only aligned the four basal ones with the corresponding cross-veins between RA and RP1; cubito-anal area broad, with three rows of cells between CuA and posterior wing margin; CuA zigzagged reaching posterior wing margin well distal (about 8 mm) of nodus level; postdiscoidal area with only one row of cells and distally narrowed; area between MA and RP3+4 distally widened; area between RP3+4 and IR2 narrow, with one row of cells; areas between IR2 and RP2 and between RP2 and IR1 distally widened with two long secondary longitudinal veins; area between IR1 and RP1 with only one row of cells, broader than long; MA and CuA distally zigzagged; MP, RP3+4, IR2 and RP2 more or less straight or slightly curved; IR1 with a distinct but smooth curve opposite pterostigma, corresponding to a narrowing of the area between it and RP1 and a broadening of the area between it and RP2; no significant increase of spine-density at the apical costal margin.

Etymology. From the Castilian “ vuelve en lucha ”, meAning returning in fight. In homage to the 30,001, alive in the dreams and commitment of the People. The specific epithet is to be considered as a noun in apposition.

Type material. MAPBAR 4139, Museo de la Asociación Paleontológica de Bariloche, San Carlos de Bariloche, Río Negro, Argentina .

Type locality. Volcanic caldera-lAKe beds, Río Pichileufú, quArry RP4 (= to field numbers “PichiPrem”), new locality discovered by AriAnA “Premgi” PAulinA CArAbAJAl in 2016 And lAterAl equivAlent to RP3 from Wilf et al. (2005), Pilcaniyeu, province of Río Negro, Patagonia Argentina, palaeolatitude ~ 46°S .

Discussion. The new specimen could be included into Frenguelliidae because they share some characters as the terminal kink of the CP very weak, not aligned with nodal Cr; nodal furrow reduced; ScP reaching costal very obliquely at nodus; nodal Cr sub-vertical; subnodus vertical; midfork symmetrical and recessed basally to a position between 12 and 26% of wing length; pterostigma elongate and broad; discoidal cell basally closed in hindwing, quite broad, distinctly widened distally; all secondary antenodal cross-veins between ScP and RA suppressed; antesubnodal space without cross-veins; cubito-anal area broad, with three rows of cells between CuA and posterior wing margin; nodus in the basal third of the wing, postnodal area very elongate; postnodal and postsubnodal cross-veins very numerous; and the petiole short and broad. The new genus could be distinguished from Frenguellia Petrulevičius & Nel, 2003 , the other genus of Frenguelliidae , because it has the terminal kink of the CP not aligned with nodal Cr but in a slightly distal position (contra in a very distal position in Frenguellia ); and the base of RP2 8 cells from nodus (contra 2-4 cells).

The presence of a discoidal cell distinctly widened distally and a much less oblique and more transverse distal side (ddcv) like in the forewing of Frenguellia correspond to an apomorphy of the clade Epiproctophora Bechly, 1996. Also, the presence of a CuP strongly curved and apparently beginning on AA ( Petrulevičius & Nel, 2003), potentiAl synApomorphy of the group And Also discussed in FlecK et al. (2004) support its attribution to Epiproctophora.

The base of the vein IR2 of Frenguelliidae is below the subnodus while it is nearly midway between the nodus and the arculus in all the Epiproctophora. This is probably an autapomorphy of FrenguelliidAe within this clAde ( Petrulevičius & Nel, 2007). This structure could be correlAted to the basal recession of the nodus. Also, the short petiolation together with the broadened wing and the sub-vertical nodal cross-vein and subnodus is a character present in some Zygoptera ( Thaumatoneuridae : Dysagrioninae) and in the Oligocene-Miocene family Sieblosiidae of enigmatic phylogenetic position, but considered Epiproctophora in several publications ( Fleck et al., 2004; Nel & Fleck, 2012). Differences with the Sieblosiidae are in the shape of the discoidal cells and position of the bases of RP3+4 and IR2 ( Petrulevičius & Nel, 2007).

The AustroperilestidAe Petrulevičius & Nel, 2005 Also present in the Eocene of PAtAgoniA Are based in a single wrinkled specimen that shows some shared characters with Frenguelliidae which could indicate its synonymy with Frenguelliidae . Only the discovery of new and more complete material is awaited to a fine comparison. Both families differ strongly in the characters of the discoidal cell placing AustroperilestidAe into the ZygopterA ( Petrulevičius & Nel, 2005). In this way, Austroperilestes Petrulevičius & Nel, 2005 could be differentiAted with Treintamilun gen. nov. by having the arcular cross-vein reaching RP+MA basal to its separation (contra after RP separation in Treintamilun gen. nov.); the RP and MA strongly approximated at their base in discoidal quadrangle (contra very distant); the pterostigma braced (contra not braced); and a curved vein between and near MA and ddcv forming a little triangle.

If Frenguelliidae are Epiproctophorans, they are not Euepiproctophorans ( Epiophlebiidae + Anisopteromorpha Bechly, 1996) because they have a different, derived pattern of alternating width of wing spaces between the longitudinal veins, and a tendency to a triangular hind wing discoidal cell traversed by one cross-vein. The Frenguelliidae are probably in a very inclusive position within the Epiproctophora, either sister group of all other Epiprotophora or sister group of the Isophlebioptera, As it shAres some potentiAl synApomorphies with this lAst group ( Petrulevičius & Nel, 2007).

Figures

Fig. 1.- Photographs of Treintamilun vuelvenlucha gen. et sp. nov., holotype MAPBAR 4139 from Río Pichileuḟ (Río Negro, Argentina); Lutetian, middle Eocene. a.- Part. b.- Counterpart. Scale bar = 3 mm.

Fig. 2.- Composite camera lucida drawing of Treintamilun vuelvenlucha gen. et sp. nov., holotype MAPBAR 4139 from Río Pichileuḟ (Río Negro, Argentina); Lutetian, middle Eocene. Scale bar = 2 mm.

Fig. 3.- Photographs of details of Treintamilun vuelvenlucha gen. et sp. nov., holotype MAPBAR 4139 from Río Pichileuḟ (Río Negro, Argentina); Lutetian, middle Eocene. a.- Discoidal cell, scale bar = 0.5 mm. b.- Basal part, scale bar = 1 mm. c.- Nodus, scale bar = 0.25 mm. d.- Pterostigma, scale bar = 0.5 mm.