Lindenia heeri, Boderau & Engel & Stössel & Nel, 2024

Boderau, Mathieu, Engel, Michael S., Stössel, Iwan & Nel, Andre, 2024, The first fossil representative of the extant clubtail dragonfly genus Lindenia from the mid-Miocene of Öhningen, Germany, Acta Palaeontologica Polonica 69 (1), pp. 23-27 : 24-26

Lindenia heeri sp. nov.

Fig. 1 .

ZooBank LSID: urn:lsid:zoobank.org:act:17FD46AF-8346-43D1-8212-D2F9E70DC592

Etymology: The specific epithet honors Oswald Heer (1809–1883), one of the founders of palaeoentomology and who discovered and published numerous insects from the Öhningen outcrop (e.g., Heer 1847). Holotype: ETH S.N. 228 (labelled “ Aeschna tyche Hr. ”), a complete forewing.

Type locality: Area around Lake Constance (Bodensee) north of the cities of Öhningen and Wangen, southern Germany .

Type horizon: Upper Öhningen beds Member, Upper Freshwater-Molasse Formation, Sarmatian, 12.7–11.6 Ma, mid-Miocene ( Selmeier 1990; Lutz 1997).

Material.— Type material only.

Diagnosis.—Forewing with 10 cells directly adjacent on posterior side of pterostigma; posterior branch of IR 2 at level of vein “O”; 12 small cells between C and RA distad to pterostigma; elongate discoidal triangle, with a distinctly curved MAb; base of IR 1 situated below basal side of pterostigma; presence of a secondary curved vein apparently emerging from posterior branch of IR 2.

Description.—A complete forewing, 44.6 mm long, 9.6 mm wide; distance from base to arculus 6.2 mm, from arculus to nodus 18.0 mm, from wing base to Ax1 4.5 mm, from Ax1 to Ax2 6.2 mm; Ax2 slightly basal to distal angle of discoidal triangle; three antenodal crossveins of first row between Ax1 and Ax2, 16 secondary antenodal crossveins of first row distal of Ax2; 13 preserved postnodals; 12 crossveins between RP and MAa basad RP 3/4; eight Bqs veins; oblique vein “O” four cells distal of subnodus; hypertriangle with two crossveins; discoidal triangle elongate, subdivided into five cells, with costal side 3.6 mm long, basal side 2.3 mm long, distal side MAb 4.1 mm long, MAb curved, with a slight angle at base of tspl; RP 3/4 and MAa weakly curved and parallel, with one row of cells between and two rows near posterior margin of wing; three rows of cells in basal part of postdiscoidal area, broadened distally; a distinct distal posterior branch of MAa, with four rows of cells between it and MAa; median area free; submedian area crossed by CuP and two other veins; PsA strong and oblique; subtriangle divided into three smaller cells; distance between nodus and pterostigma 0.9 mm; pterostigma dark brown, 6.9 mm long, 1.0 mm wide, with costal and posterior margin widened, with 10 cells directly adjacent on posterior side of pterostigma; pterostigmal brace slightly oblique, aligned with basal side of pterostigma; 12 small cells between C and RA distad to pterostigma; base of IR 1 below basal side of pterostigma, basally zigzagged, and curved distally; base of RP 2 aligned with subnodus, RP 2 regularly curved; main branch of IR 2 parallel to RP 2; posterior branch of IR 2 at level of vein “O”, well-defined with four to seven rows of cells and a well-defined secondary longitudinal vein between it and main branch; three rows of cells between posterior branch of IR 2 and RP 3/ 4 in narrower part; a secondary curved vein apparently emerging from posterior branch of IR 2; cubito-anal area broad with four rows of cells between CuA and posterior margin of wing.

Remarks.—Attribution of the wing to the family Gomphidae is supported by the following synapomorphies: distinct PsA; slight angle in the posterodistal side of the discoidal triangle caused by the presence of the tspl; anterior side of the hypertriangle curved; straight arculus ( Bechly 1996, 2003). The new fossil has an elongate discoidal triangle with a distinct tspl, which is a feature found among Gomphidae only in the subfamilies Hageniinae Davies & Tobin, 1985, and Lindeniinae . The Hageniinae have the IR 1 vein secondarily elongate, originating well basad the pterostigma. Also, the costal margin and RA are not widened along the pterostigmata. These characters are not present in the new fossil thereby excluding a placement in Hageniinae. Alternatively, Lindeniinae are characterized by the following synapomorphies: secondary branch of IR 2 very distinct, therefore IR 2 appears to be dichotomously forked distal of the lestine oblique vein; discoidal triangles divided into more than two cells; in the forewing the basal part of the subdiscoidal cell (between CuP-crossing and pseudo-anal vein PsA) is traversed by supplementary cubito-anal-crossveins; hypertriangle divided by at least two or more crossveins. All of these characters are present in the current fossil wing.

Among extant lindeniine genera, Diastatomma Burmeister, 1839 , from Africa has strongly curved distal halves of the main longitudinal veins, and many more cells (ca. 20) cells directly adjacent on the posterior side of the pterostigma, unlike the new fossil. Gomphidia Selys, 1854 (Africa and south-east Asia) and Gomphidictinus Fraser, 1942 ( Thailand, Viêt Nam, Laos). have a forewing discoidal triangle more equilateral than in the new fossil ( Fraser 1942; Garrison et al. 2015). Neotropical Cacoides Cowley, 1934a , and Melanocacus Belle, 1986 , and Ictinogomphus from Africa and south-east Asia, and its closely related genera Austrictinogomphus Fraser, 1940 (Papua), Sinictinogomphus Fraser, 1939 (East and south-east Asia), and Indictinogomphus Fraser, 1939 (Oriental, Australo-Papua), also differ from the new fossil in the forewing discoidal triangle not elongate, nearly equilateral ( Fraser 1957; Belle 1986).

The new fossil has a wing venation extremely similar to that of Lindenia tetraphylla ( Van der Linden, 1825) , especially in the elongate discoidal triangle, with a distinctly curved MAb; the base of IR 1 situated below the basal side of the pterostigma; the same shape of veins RP 2, IR 2, RP 3/4, and MAa; and the same pattern of veins in the postdiscoidal area and the area between IR 2 and RP 3/4, especially in the presence of a secondary curved vein apparently emerging from the posterior branch of IR 2. The only discernable difference is the number of cells directly adjacent on the posterior side of the pterostigma, viz. 10 in the new fossil vs. five to eight in the sole extant species of Lindenia , i.e., L. tetraphylla ( Van der Linden, 1825) .

Among fossil Lindeniinae , the oldest representative, Cratolindenia knuepfae Bechly, 2000 , is from the Lower Cretaceous of Brazil. It differs greatly from the new fossil in a more distal position of the posterior branch of IR 2, in a strongly oblique pterostigmal brace, and in having a quite broad area between RP 2 and RP 1 below the pterostigma ( Bechly 2000). The second oldest lindeniine is Burmalindenia imperfecta Schädel & Bechly, 2016 , based on the basal parts of hind wings from “mid”-Cretaceous Kachin amber. It is not possible to compare the species from Myanmar with the new fossil forewing as the former is based on a hind wing ( Schädel and Bechly 2016). Several Cenozoic fossils have been attributed to the Ictinogomphus , namely I. hassleri Schädel & Lechner, 2017 , based on a hind wing which differs from the new fossil in only six cells directly adjacent on the posterior side of the pterostigma Schädel and Lechner 2017); Ictinogomphus engelorum Nel et al., 2020 , that has a significantly different forewing discoidal triangle ( Nel et al. 2020); and “? Ictinogomphus species indet.” described by Prokop et al. (2016), known from only the apical two-thirds of a forewing, differs from the new fossil in the lower number of cells distal to the pterostigma, and only six cells directly adjacent on the posterior side of the pterostigma. Lastly, the Miocene Chinese Miopetalura would share with the new fossil the presence of ten cells directly adjacent on the posterior side of the pterostigma, but it differs from the new fossil in the forewing discoidal triangle nearly equilateral and the presence of much more secondary antenodal crossveins ( Zhang 1989: text-fig. 10).

Lastly Huang and Nel (2009) described a “ Lindeniinae , genus undetermined” from the Miocene Shanwang Formation of China. If it shares with the new fossil the presence of numerous cells covered by the pterostigma, its posterior branch of IR 2 is two cells distad to the oblique vein and its forewing is ca. 42.0 mm long vs. 44.6 mm in the new fossil.

Stratigraphic and geographic range.—Upper Öhningen beds Member, Upper Freshwater-Molasse Formation, Sarmatian, 12.7–11.6 Ma, mid-Miocene.

Figures

Fig. 1. Clubtail dragonfly Lindenia heeri sp. nov., holotype, ETH S.N. 228 from Upper Öhningen beds Member, mid-Miocene. Forewing photographed under standard light (A1) and UV light (A2).