Furagrion ansorgei ( Zessin, 2011 ) Archibald & Ware & Rasmussen & Sylvestersen & Olsen & Simonsen, 2023

Archibald, S. Bruce, Ware, Jessica L., Rasmussen, Jan A., Sylvestersen, René L., Olsen, Kent & Simonsen, Thomas J., 2023, The damselfly genus Furagrion Petrulevičius et al. (Odonata, Zygoptera) from the early Eocene Fur Formation of Denmark and the dysagrionoid grade, Zootaxa 5278 (2), pp. 289-317 : 312-314

Furagrion ansorgei ( Zessin, 2011) comb. nov.

Figs. 22–23

Emended diagnosis. The wing of Furagrion ansorgei may be distinguished from those of F. jutlandicus as in its diagnosis, above.

Emended description. Holotype: see genus description and its distinctive character states in the diagnosis of F. jutlandicus .

Type material. Holotype ( Fig. 23 ) MOA 770/1, 2: likely a forewing by its slender shape ( Fig. 23B ), coll. Jörg Ansorge, northern coast of Mors, Skaerbaek, Fur Formation, in a calcareous concretion, in the Natural History Museum, Natural Research Society Mecklenburg, Natureum at Ludwigslust Castle (part) and Natural History Museum of Denmark, Copenhagen, Denmark (counterpart). We were not able to examine the fossil as the part and counterpart could not be located at the institutions listed. Our discussion is based on Zessin’s (2011) description and illustrations, and a higher resolution copy of his figure 3 provided by Jörg Ansorge.

Other material. MGUH 34113 ( Fig. 22 ) tentatively belongs to the species: a complete forewing in a concretion, coll. Thomas Klode on Fur Island, Knudeklint Member, possibly between ash layers -11 and -13, Fur Formation, 1968, in the Natural History Museum of Denmark, University of Copenhagen.

Range and age. Earliest Ypresian Fur Formation , Jutland, Denmark. Range: see type and other material, above.

Remarks. With the ability to examine a larger sample of Furagrion specimens than was available to Zessin (2011), we find that the character states of Morsagrion that he proposed would separate it from Furagrion do not do so. These are:

1- The RA-RP1 space is two cells wide from about the middle of the level of the pterostigma.

- We find this difficult to discern from his fig. 3 photograph and we are not confident that this is established.

2- The form of the pterostigma.

- We find that it does not significantly differ.

3- The relationship between Zessin’s “premedial cell” (“prmc”) and the cells below it in the MA-MP space. The premedial cell is the space between RP to slightly past the base of RP3-4 and MA without crossveins from the arculus to the first crossvein between RP-3-4 and MA. He excludes the quadrangle and counts four cells in the MA-MP space subtending this in Morsagrion and two cells in this space in Furagrion .

- By our count, this is about three and a half cells long in M. ansorgei , and in the larger sample of Furagrion available to us, two (e.g., FUM-N 13856, Fig. 2 ) to four (FUM-N 14704, Fig. 17 ) cells long and, therefore, consider this to be within intraspecific variation.

4- The number of cells in the precubital field (MP-CuA space) to the level of the origin of RP3-4 (three in Morsagrion n. gen., four at Furagrion ).

- Like Zessin, we count three in M. ansorgei , but with our larger sample we find between two (hind wings of MM-10752) to five (FUM-N 11146) in Furagrion . We, therefore, also consider this to be intraspecific variation.

5- Eight cells between the beginning of IR2 and RP 2 in Morsagrion and five in Furagrion . This varies from eight cells in Henriksen’s type MGUH 1819 to five in FUM-N 13856, with fewer in hind wings, e.g., MM-10750 with 7.5 and 6.5 cells in the forewings and 4.5 in the hind wing.

- In all of these except MGUH 34113, which we tentatively associate with MOA 770, the IR1-RP2 space is more than one cells wide distad about the level of the pterostigma base (see below).

6- The shape of the discoidal and subdiscoidal cell.

- We find that this does not greatly differ.

7- The length of the double rows of cells in the IR1-RP2 space.

- This space is more than one cell wide for only about three cells from ending on the wing margin, whereas in F. jutlandicus , this space is more than one cell wide to about the level of or slightly more basal of the basal end of the pterostigma. This occurs in all Furagrion specimens that we examined except possibly MGUH 34113 (below) and does appear distinctive.

We, therefore, find that MOA 770/1and MGUH 34113 do not differ enough from the fossils assigned here to F. jutlandicus to justify placing them in a separate genus, and so treat Morsagrion as a junior synonym of Furagrion .

Character state 7 of MOA 770 does appear distinctive among the Furagrion specimens examined (but see MGUH 34113 , below), supporting its status as a separate species. However, while it is shown in Zessin’s drawing (his figs. 1 and 4), this region appears unclear in his photograph (his fig. 3) and in a slightly higher resolution version of it provided by J. Ansorge (see our drawing made from this, Fig. 23 ). We consider this character state as tentative until the type specimen can be examined.

The shape of wing MOA 770 provides stronger support for recognizing it as a separate species ( Fig. 23B, 23C ). It has a greater length / width ratio than all Furagrion wings, fore- or hind, by all length measurements except RP2 to apex / width ( Tables 2 and 3 and see PCA, above).

By these reasons, we treat MOA 770 as Furagrion ansorgei (Zessin) comb. nov.

MGUH 34113 ( Fig. 22 ) might be conspecific with MOA 770: Its IR1-RP2 space becomes more than one cell wide closer to the level of the distal end of pterostigma than basal, suggesting an association with F. ansorgei MOA 770. This is, however, not as distinct as in Zessin’s drawing of the MOA 770 wing. More importantly, this wing is relatively narrow like MOA 770. Furthermore, it is smaller (see PCA and Tables 3 and 4 ), although this might represent intraspecific variation or sexual dimorphism. Given this uncertainty, we tentatively treat this specimen as F. ansorgei .

Figures

FIGURE 2. FUM-N 13856, with which Petrulevičius et al. (2008) defined Furagrion (as ERK-KL-T1): A, photograph; B, drawing. Both to scale, 5 mm. A forewing. Ax1, Ax2 = antenodal cross veins 1 and 2; arc = arculus; b = brace vein; CuA = anterior branch of the cubitus; IR1, IR2 = intercalar vein 1 and 2; MA, MP = the anterior and posterior branches of the media; nod = nodus; pt = pterostigma; Q = quadrangle; RA = radius anterior; RP1, RP2, RP3-4 = branches of the radius posterior; sn = subnodus; * = origin of RP2.

FIGURE 17. FUM-N 14704: A, photograph; B, drawing. A forewing. Both to scale, 5 mm.

FIGURE 22. MGUH 34113, a forewing: A, photograph of the part; B, photograph of the counterpart; C, drawing from both A and B. Note infuscation very light on the part as preserved, darker on the counterpart (see text). All to scale, 5 mm.

FIGURE 23. A, Furagrion ansorgei MOA 770 redrawn from a higher resolution copy of Zessin’s (2011) figure 3 photograph provided by J. Ansorge; shape compared with that of the proposed neotype (blue) B, forewing; C, hind wing. A to scale, 5 mm; B, C wings to no scales, the sizes of proposed neotype wings are adjusted to match arculus to apex and anterior wing margin of MOA 770 to compare shape.