Palaeophylolestes distinctus, Doriath-Döhler & Hervet & Béthoux, 2023

Doriath-Döhler, Aimie, Hervet, Sophie & Béthoux, Olivier, 2023, Palaeophylolestes distinctus n. gen., n. sp., a new malachite damselfly (Odonata: Zygoptera: Synlestidae) from the Paleocene Menat locality (France), Geodiversitas 45 (14), pp. 401-407 : 402-405

Palaeophylolestes distinctus n. gen., n. sp.

( Figs 1 ; 2 )

urn:lsid:zoobank.org:act:E1287128-20FA-4391-90E2-B1ABF30C00A6

HOLOTYPE. — BDL 2002 , Musée de Paléontologie de Menat ¸ Menat, Puy-de-Dôme, France.

ETYMOLOGY. — The species epithet refers to the length of MA, MP and CuA, distinctly long in the species.

TYPE LOCALITY AND STRATIGRAPHY. — Bord du Lac des Grelins ( BDL), Menat, Puy-de-Dôme, France; middle Paleocene, Menat Basin.

COMMENTED DIAGNOSIS. — Wings: RP1+2 / RP3+4 fork closer to nodus than to arculus (within Lestoidea, apomorphic for Synlestidae and Perilestidae ); MA, MP and CuA reaching posterior wing margin very distally (unique to the species); forewing quadrangle with proximal edge about half length of posterior edge; cell below sub-discoidal (i.e. sub-quadrangular) cell well-developed, longer than sub-discoidal cell (plesiomorphy within Zygoptera ; as opposed to ‘cell reduced, with AA (or CuP+ AA) diverging from posterior wing margin in distal position’).

DESCRIPTION

General aspects

Specimen preserving thoracic segments, fragments of a leg, 4 abdominal segments, and more or less complete wings, with pairs of one side largely overlapping; forewing of second pair (FW2) very damaged, creased along multiple folds, with a main disruption running along MA-MP area.

Wing venation (essentially derived from HW1)

Two antenodals in ScP-R area; at least 8 postnodals (as preserved in HW1), probably 11 or 12 originally in hindwing, and probably more in forewing; subnodus short, oblique; cross-veins between RA and RP1/RP1+2 aligned with postnodals near nodus, slightly misaligned with them near pterostigma; pterostigma extending over four cells (in the RA-RP1 area); quadrangle trapezoidal (as opposed to quadrangular) with proximal edge about ½ of posterior edge in forewing, less than ½ in hindwing (i.e. quadrangle slightly narrower and longer in hindwing); RP1+2 / RP3+4 fork located closer to nodus than to arculus; Irp 1+2 -rp 3+4 starts opposite subnodus; RP1 / RP2 fork located proximally, just before postnodal 4; area between Irp 1 -rp 2 and RP2 with 3 rows of cells at its broadest (probably forming one or two supplementary sectors); RP3+4-MA area broadening near posterior wing margin (broader than surrounding areas), with at least 3 rows of cells; MA very long, reaching posterior wing margin opposite beginning of pterostigma in hindwing (as observed in HW1), possibly longer in forewing (opposite pterostigma mid-length); MA-MP area with a single row of cells except in most distal part (preserved in hindwing, possibly present in forewing); MP slightly arched upwards at its point of divergence from MP+CuA, simple and rectilinear, long; MPCuA area comparatively broad (broader than the MA-MP area), with a single row of cells; CuA long, mostly parallel to posterior wing margin; a single row of cells between CuA and posterior wing margin; cell located below sub-discoidal (i.e. sub-quadrangular) cell (i.e. anteriorly delimited by AA) well-developed, longer than sub-discoidal cell; in most areas cross-venation scalariform and forming quadrangular cells; cross-veins sigmoidal, reticulated and denser distal to pterostigma, reticulated near apex, and in RP3+4-MA area.

Dimensions

Forewing, length about 25.4 mm, maximum width about 4.9 mm (both estimated from FW1); hindwing, length 23.6 mm, width 5.3 mm (deduced from HW1).

REMARKS

Within Lestoidea (as delimited in Bybee et al. 2021; and see Kohli et al. 2021), the new specimen can be assigned to the Synlestidae based on a particular combination of character states. The occurrence of the state ‘RP1+2 / RP3+4 fork located closer to nodus than to arculus’ is unique to this family indeed (see Garrison et al. [2010] and Fig. 3 ; the RP1+2 / RP3+4 fork is located closer to the arculus in Lestidae , Menatlestidae and Eolestidae , very close or opposite to the nodus in Hemiphlebiidae , and beyond it in Perilestidae ; exceptions occur within Synlestidae , see Fig. 3B ; see Bridges 1994, Greenwalt & Bechly 2014, Nel & Jouault 2022). This assignment is also consistent with the position of the arculus being closer to the nodus than to the wing

A ScP

RA RP1 1-rp2 B ScP CuA MP MA RP3+4 Irp1+2-rp3+4

RA RP1 1-rp2 C ScP CuA MP MA RP3+4

RA RP1 1-rp2 RP3+4 CuA MP MA

base (see Tillyard 1917; more or less midway between the base and the nodus in Lestidae ; closer to the wing base in Hemiphlebiidae , Eolestidae and Menatlestidae; conversely, very close to the nodus in Perilestidae ), and the presence of intercalary veins in the area between Irp 1 -rp 2 and RP2 (absent in Hemiphlebiidae and Perilestidae ; also present in Lestidae , Eolestidae and Menatlestidae).

It must be mentioned that, outside of Lestoidea, the Megapodagrionidae and the Coenagrionidae also display the state ‘RP1+2 / RP3+4 fork located closer to nodus than to arculus’. However, assignment to the former can be excluded owing to the quadrangular shape of the quadrangle. As for the latter, Coenagrionidae have a single row of cells in the area between Irp 1 -rp 2 and RP2, while the new material has 3, as in Synlestidae .

The new specimen differs from all known Synlestidae by the very long MA, MP and CuA. Also, the quadrangle, characterised by a comparatively long proximal edge, is atypical compared to known Synlestidae . Additionally, unlike in Synlestes Selys Longchamps, 1868 (see Fig. 3A ) and a number of other extant genera, including Chlorolestes Selys Longchamps, 1862b , Ecchlorolestes Barnard, 1937 , Episynlestes Kennedy, 1920 and Sinolestes Needham, 1930 (see Bridges 1994; Simaika et al. 2020; and references therein) as well as some extinct genera such as Madres Petrulevičius, 2018 and Inacayalestes Petrulevičius, 2015 (both Eocene, Argentina), the cell located below the sub-discoidal cell (colour-coded in light blue in Figs 2 , 3 ) is well-developed (i.e. AA diverges from the posterior margin in a basal position) in the new specimen. This state is shared with species of Megalestes Selys Longchamps, 1862a ( Fig. 3B ) and the monotypic genus Phylolestes Christiansen, 1947 ( Fig. 3C ). It is likely a plesiomorphic condition. The new specimen sharply differs from Megalestes spp. in the location of the RP1+2 / RP3+4 fork (unusually basal, for a Synlestidae , in Megalestes ). Finally, the new specimen is overly similar to Phylolestes ethelae Christiansen, 1947 . However, in addition to traits highlighted above, RP3+4 is more rectilinear in the new specimen (distally, it remains parallel to the posterior wing margin for some distance in Phylolestes ethelae ). Finally, comparison with Cretaphylolestes cretacicus Huang, Fu, Lian, Gao & Nel, 2022 (Lower Cretaceous, China) is made difficult by the fragmentary state of the available material. Moreover, the overlapping of elements belonging to fore- and hindwing jeopardizes the identification of critical elements, such as the quadrangle shape, in this species. Given the above, the erection of a new species and genus is justified.

Figures

FIG. 1. — Palaeophylolestes distinctus n. gen., n. sp., holotype specimen (BDL 2002), overview; A, drawing; B, photograph (embedding matrix used as white reference). Scale bar: 5 mm.

FIG. 2. — Palaeophylolestes distinctus n. gen., n. sp., holotype specimen (BDL 2002), drawings of wings, isolated (see Fig. 1 for their respective locations; faded vein portions reconstructed); A, B, first pair (located on the left side of the complete specimen); A, forewing; B, hindwing; C, D, second pair (located on the right side of the complete specimen); C, forewing; D, hindwing. Scale bar: 5 mm.

FIG. 3. — Forewings of selected extant representatives of the Synlestidae Tillyard, 1917: A, Synlestes weyersii Selys Longchamps, 1868 (male; based on photograph by John Tann [Sydney, Australia], CC BY 2.0); B, Megalestes gyalsey Gyeltshen, Kalkman & Orr, 2017 (male; based on Payra et al. 2021: fig. 2F, approximate scale); C, Phylolestes ethelae Christiansen, 1947 (male; based on Garrison et al. 2010: fig. 527). Scale bars: 5 mm.