Menatagrion hervetae, Nel & Jouault, 2022

Nel, André & Jouault, Corentin, 2022, The odonatan insects from the Paleocene of Menat, central France, Acta Palaeontologica Polonica 67 (3), pp. 631-648 : 634-641

Menatagrion hervetae sp. nov.

Figs. 3–6 .

ZooBank LSID: urn:lsid:zoobank.org:act:0545DECE-66A0-49E3-8403-97668D054455

Etymology: Named after Sophie Hervet, curator of the collections of fossils at the Musée of Menat town. The specific epithet is to be treated as a noun in the genitive case.

Holotype: MNT Nel Odo 1 (imprint and counterimprint).

Type locality: New quarry, Menat, Puy-de-Dôme, France.

Type horizon: Middle Paleocene, Menat Basin.

Material.— Holotype and another specimen MNHN ‘ 4/10/ 1973, Menat 63/64) imprint and counterimprint of a wing apex (showing the same pattern of coloration and same pterostigma and areas between C and RA and between RA and RP1).

Diagnosis.—Wing venation characters only. Arculus opposite Ax2; three secondary antenodals between C and RA distal of Ax2; base of RP3/4 at basal fourth of space between arculus and nodus; base of IR2 midway between arculus and nodus; two-three rows of cells between RA and RP1 below pterostigma; no pterostigmal brace; one-two rows of cells between C and RA distal of pterostigma; two rows of cells between CuA and posterior wing margin; CuA nearly straight and elongate; no oblique vein “O”; postdiscoidal area greatly widened distally, with two secondary longitudinal veins between MAa and RP3/4.

Description.—Head and legs missing; meso-metathorax and abdomen only partly preserved; one forewing nearly complete with distal half darkened and basal half hyaline; other wings only partly preserved; wing ca. 27.0 mm long, 8.1 mm wide; distance for base to arculus 4.7 mm, from arculus to nodus 5.8 mm, from nodus to pterostigma ca. 16.7 mm, from pterostigma to wing apex 4.1 mm; distance between Ax1 and Ax2 1.4 mm; Ax2 opposite arculus; three secondary antenodals distal of Ax2 between C and RA; nodus of normal shape, without ScP prolonged distad nodus; nodal crossvein and subnodus aligned and of distinct normal obliquity; base of RP3/4 1.4 mm of arculus, at basal fourth of distance between arculus and nodus; base of IR2 midway between arculus and nodus; numerous postnodal crossveins (ca. 25– 30), not aligned with postsubnodals; pterostigma elongate, 3.5 mm long, 1.0 mm wide, with basal side with a normal obliquity and a distal side curved, covering seven cells, disposed in two irregular rows, no pterostigmal brace; one-two row of cells between C and RA distal of pterostigma; two-three rows of cells between RA and RP1 for a distance of 8.3 mm basad pterostigma to wing margin; base of RP2 three cells, 2.0 mm distad subnodus; no oblique vein “O”; base of IR1 three cells distad that of RP2; two rows of cells between RP1 and IR1, and between IR1 and RP2; all main veins nearly straight basally and smoothly curved distally; two zigzagged intercalary longitudinal veins between RP2 and IR2, three between IR2 and RP3/4; two between RP3/4 and MAa; one row of cells in basal half of postdiscoidal area and eight along posterior wing margin; one row of cells between MP and CuA; two rows of cells between CuA and posterior wing margin; CuP just distad base of AA; petiole 3.5 mm long, 1.8 mm wide; forewing discoidal cell with basal side 0.4 mm long, anterior side 0.8 mm long, distal side MAb 0.8 mm long, posterior side 1.3 mm long; hind wing discoidal cell with basal side 0.5 mm long, anterior side 1.0 mm long, distal side MAb 0.8 mm long, posterior side 1.0 mm long.

Remarks.—This new zygopteran differs from Valerea multicellulata in the presence of only one row of cells between C and RA distad the pterostigma and the absence of crossveins ending into the basal side of the pterostigma ( Garrouste et al. 2017). It also differs from Thanetophilosina menatensis in the positions of the bases of IR2 and RP3/4, basad midway between arculus and nodus, vs. well distad this point (Nel et al. 1997).

The new Zygoptera has a very broad discoidal cell, a character present in the species of the fossil families Dysagrionidae , Sieblosiidae , Whetwhetaksidae , and Frenguelliidae , known between the Cretaceous and the early Miocene, with a maximum diversity during the Paleogene.

The basal positions of the bases of RP3/4 and IR2 are present in the Sieblosiidae . The new fossil differs from the representatives of this family, except the species of the Oligolestes , in possessing a subnodus of normal obliquity and ScP not passing through the nodus. It is possible that Oligolestes belongs to the stem-group of the Sieblosiidae , as the sieblosiid Paraoligolestes has a wing venation very similar to that of Oligolestes , with the only difference in the structure of the nodal veins ( Nel and Escuillié 1993). Other differences between the new fossil and all the Sieblosiidae (including Oligolestes ) are the vein CuA nearly straight (vs. distinctly curved), and the absence of the oblique vein “O”.

The new fossil differs from the Whetwhetaksidae owing to the arculus opposite Ax2 (vs. nearly opposite Ax1), and the presence of secondary antenodals. However, they share the bases of RP3/4 and IR2 closer to arculus than to nodus, the absence of the oblique vein “O”, and CuA less curved than in the Sieblosiidae . The Frenguelliidae have an oblique vein “O”, a vertical subnodus, and the base of IR2 opposite the subnodus, configuration not found in the new fossil.

The new fossil preserves several diagnostic characters of the Dysagrionidae , as proposed by Archibald et al. (2021: 16–17): oblique crossvein “O” absent; arculus at or immediately proximad Ax2 (here opposite Ax2); discoidal quadrangle broad, with distal side longer than proximal side, posterior side longer than anterior, distal-posterior angle oblique, proximal-anterior angle usually about 90°; nodus positioned at least a quarter wing length, usually more (here nearly at a third); vein AA separating from AP briefly before joining CuP (a character also present in many Lestoidea); CuA–A space expanded in middle to at least two cells wide, often more (here two rows of cells); CuA long, terminating on posterior margin at mid-wing or longer. Nevertheless, the new fossil differs from the species of Dysagrionidae in an important character also present in the species of Sieblosiidae , viz. RP3–4 originating at one quarter length from arculus to subnodus, vs. roughly between one third to two thirds (usually about two thirds). Also all of the species of Dysagrionidae , except Congqingia rhora and the Petrolestes spp. , have the base of IR2 below the subnodus. In the two latter genera and the new fossil, the base of IR2 is midway between the arculus and the nodus. The new fossil and Congqingia rhora differ from the species of Petrolestes in the cubital area with only two rows of cells. The new fossil differs from both Congqingia rhora and the species of Petrolestes in the postdiscoidal area greatly widened distally, with two secondary longitudinal veins between MAa and RP3/4 (vs. with one-two rows of cells in-between). Such a widening of the posdiscoidal area is also found in the other dysagrionid genera.

Archibald et al. (2021: 17) listed the absence of secondary antenodals as a diagnostic characters of the Dysagrionidae . But they also included in this family the two genera Phenacolestes and Electrophenacolestes that have three secondary antenodal crossveins distal of Ax2, between C and RA. This character is also present in the new fossil. It differs from Phenacolestes and Electrophenacolestes in the narrower cubital area with only two rows of cells (vs. three-four rows of cells), and the base of IR2 midway between arculus and nodus (vs. below subnodus).

In conclusion, we tentatively place the new fossil in the Dysagrionidae , even if it clearly differs from all the genera and species currently included in this family. As it also shares some characters with the Sieblosiidae , it is only after a new phylogenetic analysis of all these damselflies that its relationships will be clarified.

Stratigraphic and geographic range.— Type locality and horizon only.

Lestinoidea Calvert, 1901 (sensu Bechly 2016)

Family Menatlestidae nov.

ZooBank LSID: urn:lsid:zoobank.org:act:1F1AB163-E015-449B-862D-FF08A8233D56

Type genus: Menatlestes gen. nov.

Genera included: Type genus only.

Diagnosis.—Wing venation characters. Discoidal cell narrow, with elongate anterior and distal sides, and a very acute postero-distal angle; subdiscoidal cell very long and narrow, posteriorly closed; base of RP3/4 midway between arculus and nodus; base of IR2 at distal third between arculus and nodus, well basal of subnodus; Ax2 opposite arculus; three secondary antenodals distal of Ax2; numerous postnodals, not aligned with postsubnodals; pterostigma elongate, with an oblique pterostigmal brace; cubital area very narrow; no oblique vein “O”.

Genus Menatlestes nov.

ZooBank LSID: urn:lsid:zoobank.org:act:618A75FA-3552-49D2-97EC-7067F5DA3442

Type species: Menatlestes palaeocenicus sp. nov.; see below.

Etymology: Named after the type locality Menat, and the genus name Lestes . Gender feminine.

Diagnosis.—As for the type species by monotypy.

Remarks.—The presence of a very oblique distal side MAb of the discoidal cell excludes an attribution to the Dysagrionidae , Sieblosiidae , and Whetwhetaksidae . The absence of an oblique crossvein “O” further excludes affinities with the Sieblosiidae . The base of vein RP3/4 basad midway between arculus and nodus, and that of IR2 just distad the latter, plus the elongate pterostigma exclude affinities with the Eocene Frenguelliidae and with the majority of the Coenagrionomorpha ( Petrulevičius and Nel 2003b, 2007; Bechly 2016). These characters are present in some Caloptera and Lestomorpha. In the Coenagrionomorpha, only the Hypolestidae have rather elongate pterostigma as in Menatlestes gen. nov. In this family, only the Hypolestinae share with Menatlestes gen. nov. the bases of IR2 and RP3/4 midway between arculus and nodus, unlike Heteragrion and Philogenia ( Münz 1919) . The genus Philosina is excluded because it has a broad cubital area, and base of IR2 below subnodus ( Ris 1917). Rhipidolestes and Lestomima have a base of IR2 well basad the subnodus, but both differ from Menatlestes gen. nov. in the basal side of the pterostigma strongly oblique, a very long anterior side of the discoidal cell, quite longer than MAb, and a broader cubital area ( Münz 1919; May 1933). The Eocene Anglohypolestes and Eohypolestes, Oligocene Prohypolestes , and the extant Hypolestes share with Menatlestes gen. nov. the bases of IR2 and RP3/4 midway between arculus and nodus, plus general patterns of venation, including a narrow cubital area (unknown in Eophypolestes), but all differ from the new fossil in having a shorter pterostigma and a very long anterior side of the discoidal cell, quite longer than MAb ( Calvert 1893; Münz 1919; Nel and Paicheler 1994; Nel and Fleck 2014).

Affinities with nearly all the Caloptera could be excluded because of the presence of a clearly oblique pterostigmal brace and long petiole in Menatlestes gen. nov. Only the Pseudolestidae show similarities with Menatlestes gen. nov. in the presence of a long petiole, bases of IR2 and RP3/4 between arculus and nodus, and narrow cubital area. However, Pseudolestes has the bases of IR2 and RP3/4 very close to arculus and a MAb short and not strongly oblique, unlike Menatlestes gen. nov.

Indeed, a strongly oblique MAb is only found in some Lestomorpha, supporting an attribution of Menatlestes gen. nov. to this clade. The Cretaceous Protohemiphlebiidae and the Hemiphlebiidae are excluded because they have RP1 kinked at the insertion of the pterostigmal brace vein and all intercalary veins suppressed, unlike Menatlestes gen. nov. ( Zheng et al. 2021). Nevertheless the Cretaceous Cretahemiphlebia has a discoidal cell with an elongate and strongly oblique MAb and a very narrow subdiscoidal cell very similar to those of Menatlestes gen. nov. ( Jarzembowski et al. 1998). The Cretaceous Cretacoenagrionidae ( Cretacoenagrion Jarzembowski, 1990 ) have the base of IR2 below the arculus. The Cretaceous Lestoidea of uncertain affinities Cretalestes Jarzembowski, Martinez-Declos, Bechly, Nel, Coram, and Escullié, 1998 , has also a very narrow subdiscoidal cell and a strongly oblique MAb, but its anterior side of discoidal cell is very short and the base of RP2 is aligned with the subnodus, unlike Menatlestes gen. nov. ( Jarzembowski et al. 1998). The Eolestidae (Eocene Eolestes ) have a discoidal cell very similar to that of Cretalestes . An additional difference with Menatlestes gen. nov. is the broad area between MP and CuA with four rows of cells, instead of one in Menatlestes gen. nov. ( Greenwalt and Bechly 2014). The Eocene Lutetialestes Greenwalt and Bechly, 2014 , also differs from Menatlestes gen. nov. owing to a similar character (two rows of cells between MP and CuA, even if some fossil and extant Lestes Leach, 1815 , have also two rows, while others have only one row of cells). It also differs from Menatlestes gen. nov. in having a shorter anterior side of the discoidal cell. The Eocene Austroperilestidae share with Menatlestes gen. nov. a very long and strongly oblique MAb and a very long pterostigma, but the anterior side of its discoidal cell is quite short; also the base of IR2 is below subnodus and it has two rows of cells in cubital area ( Petrulevičius and Nel 2005).

The Chorismagrionidae ( Chorismagrion ) and the Perilestidae ( Perilestes , Nubiolestes , Perissolestes ) have a posteriorly opened subdiscoidal cell, a short pterostigma, and the base of RP3/4 below or distad the subnodus ( Münz 1919; Kennedy 1941; Schmidt 1942). The Synlestidae have also posterior margin of the subdiscoidal cell mostly fused to the posterior margin of wing. Synlestes Sélys-Longchamp, 1869 , has a discoidal cell very similar to that of Menatlestes gen. nov., but the base of its RP3/4 is located below the nodus. The Lestinoidea (Megalestidae and Lestidae ) share with Menatlestes gen. nov. the midfork basally recessed midway between arculus and nodus. The Lestidae and the enigmatic Eocene genus Promegalestes have an oblique vein “O”, unlike Menatlestes gen. nov. and Megalestes Sélys-Longchamp, 1862 ( Münz 1919; Petrulevičius and Nel 2004b). Also, all Megalestidae and Lestidae have a short anterior side of the discoidal cell, unlike Menatlestes gen. nov.

The Eocene Latibasalidae share with Menatlestes gen. nov. the bases of RP3/4 and IR2 midway between arculus and nodus, but they have a MAb of inverted obliquity and a broad cubital area, unlike Menatlestes gen. nov. ( Petrulevičius and Nel 2004 a, 2007).

As the new fossil cannot fit in any damselfly family, we propose a new family, genus and species to accommodate its particular wing venation. Owing to the differences mentioned above, this new family likely belongs to the stem-group of the Lestinoidea.

Figures

Fig. 3. Zygopteran odonatan Menatagrion hervetae gen. et sp. nov., holotype MNT Nel Odo 1; from Paleocene, Menat, France. Imprint (A1, A2), counterimprint (A3). Scale bars 1 mm.

Fig. 4. Wing of zygopteran odonatan Menatagrion hervetae gen. et sp. nov., holotype MNT Nel Odo 1; from Paleocene, Menat, France. Counterimprint A1), wing apex, imprint (A2). Scale bars 2 mm.

Fig. 5. Reconstructions of wing of zygopteran odonatan Menatagrion hervetae gen. et sp. nov., holotype MNT Nel Odo 1; from Paleocene, Menat, France. Wing (A1), apex (A2), base (A3), base (A4), and nodus (A5) region. Scale bars 2 mm.

Fig. 6. Zygopteran odonatan Menatagrion hervetae gen. et sp. nov., MNHN ‘4/10/1973, Menat 63/64; from Paleocene, Menat, France. Imprint (A1), counterimprint (A2). Scale bars 2 mm.