Morsagrion Zessin. As 2011

Morsagrion Zessin, 2011: 65. Type species: Morsagrion ansorgei Zessin, 2011, by original designation. Syn. nov. Figs. 1–4, 6–8, 1124. Included species. Furagrion jutlandica (Henriksen, 1922), Furagrion ansorgei (Zessin, 2011) comb. nov. Range and age. Earliest Ypresian Fur Formation, Jutland, Denmark. Specimens of this genus are known to range from just below ash layer -13 within the Knudeklint Member to the lower part of the Silstrup Member (the ash layer +25 – +30 interval) of the Fur Formation, which has an absolute age of approximately 55.5 Ma (Storey 2007, Stokke et al. 2020). Six of the sixteen examined fossils, however, are from unknown levels within the Fur Formation. Emended diagnosis. The wings of Furagrion differ from those of similar extant and extinct Zygoptera by possession of all nine wing character states of the Dysagrionidae Cockrerell (Cephalozygoptera) diagnosis listed below, but the genus is excluded from that family and suborder by their zygopteran bulging, hemispherical compound eyes set far apart on a short head (see Archibald et al. 2021). Wings most easily distinguished from those of other Zygoptera and from taxa that possess many of the nine wing character states listed below and might be Zygoptera or Cephalozygoptera as follows: from Viridiflumineagrion Nel by pterostigma ca. 2.5 times longer than wide [ca. 4.7 times], from Miopodagrion Kennedy by C-RA space distad pterostigma with one row of cells [apparently two full rows]. Wings distinguished from genera with similar wings without an associated head by one or more of the following: 10, C-RA space distad pterostigma almost always with a single row of cells, rarely a few rows two cells wide immediately distad pterostigma; 11, CuA-A space usually two, sometimes maximum three cells wide; 12, possession of a brace vein; 13, no accessory (“secondary”) antenodal crossveins: Allenbya Archibald and Cannings: [10: 2 and 3 cells wide throughout]; Valerea Garrouste et al.: [10: many, up to five cells wide]; Thanetophilosina Nel et al.: [12: no brace vein]; Electrophenacolestes Nel and Arillo: [11: up to five wide, 13]; Menatagrion Nel and Jouault, 2022 [12, 13]; Chickaloon specimen of Garrouste & Nel (2019): [11: up to four wide]; Specimen MeI6572 (Megapodagrionidae genus and species A of Petrulevičius et al. 2008, cf. Megapodagrionidae genus and species A of Archibald et al. 2021): [10: most of C-RA space two cells wide]. Emended description. Head short. Compound eyes bulging, hemispherical, set apart twice their width in dorsal aspect. Thorax, legs generalised as known by preservation. Forewing. Membrane darkly infuscate, but some might be hyaline as preserved (see below). Measurements, ratios of these see Tables 1 and 2. Antenodal crossvein Ax0 absent, Ax1 and Ax2 somewhat lengthened to moderately expand antenodal space. No accessory antenodal crossveins. Pterostigma ca. 2–3 times longer than wide; anterior, posterior margins oblique; subtends 2–3 cells; distinctly oblique brace vein at basal-posterior corner in RA-RP1 space. Crossveins in postnodal, postsubnodal spaces mostly aligned basally, usually not distally. C-RA space distad pterostigma almost always with a single row of cells, rarely briefly two cells wide (see F. jutlandicus proposed neotype, Figs. 3–4); RA meets margin at or very near apex; slightly upturned near margin. Wing dense with cells throughout. RP2: origin 6.5–9 cells distal to origin of IR2. IR2: origin at or very near, basal to subnodus. RP3-4: origin about 3/5 from arculus to subnodus. Arculus at or very close basad Ax2. All major veins linear except MA zigzagged distad ca. mid-way between arculus, termination; CuA zigzagged, slightly near quadrangle, increasingly toward terminus. No crossvein O. CuA terminates on posterior margin ca. mid-way between nodus, apex; CuA–A space 2–3 cells wide at widest. Hind wing. Like forewing except shorter relative to width; measurements, ratios of these see Tables 1 and 2. Abdomen generalised as known by preservation. Remarks. Proposed neotype designation. Henriksen’s (1922) holotype and only specimen then known (Fig. 1) is incomplete, consisting of two wings that are partially complete distal to the nodus, the mid-posterior fragment of a third, and an abdomen that is complete except for a portion of its base (MGUH 1819, Natural History Museum of Denmark, University of Copenhagen, Denmark). Lacking information from the diagnostically important antenodal region of the wings, he assigned the species to Phenacolestes, an extinct genus of the extinct suborder Cephalozygoptera known from the Eocene and possibly Miocene (see table 3 of Archibald et al. 2021) with similar venation in its preserved portions. Cockerell (1908) had assigned the genus to the Dysagrioninae, then a zygopteran subfamily of Agrionidae Leach (now Calopterygidae Sélys). Recognising the limitations of the incomplete type specimen, Nel & Paicheler (1994) considered the species ‘ Phenacolestes ’ jutlandica as family indet. Rust (1999) expressed even less confidence in the generic assignment, treating the species as ‘Dysagrioninae gen. indet. jutlandica ’, illustrating it (his fig. 4 and plate 1, fig. a) with the non-type specimen FUM-N 13856 (then ERK KL Tl), an almost complete isolated wing and 14M-A2163 (his plate 1, fig. b). Petrulevičius et al. (2008) assigned the species to their new, monotypic genus Furagrion based on ERK-KL-T1 (FUM-N 13856) (Fig. 2). Zessin (2011) subsequently described Furagrion morsi and Morsagrion ansorgei, erroneously citing FUM-N 13856 (as ERK-KL-T1) of Petrulevičius et al. as the holotype of Furagrion jutlandicus. Archibald et al. (2021) considered Furagrion a dysagrionid in the Cephalozygoptera. We agree that FUM-N 13856 is conspecific with Henriksen’s holotype by the extensive similarity of all preserved parts. Despite subsequently being treated as the specimen of reference, this fossil was not designated a neotype, however, and lacks the head, necessary for assessing family and suborder affinities (see below). Therefore, to bring clarity and nomenclatural stability to the Furagrion concept, we will be requesting in a forthcoming Case to the International Commission on Zoological Nomenclature that they designate as neotype of Phenacolestes jutlandicus specimen MM-10752, which is a well-preserved specimen in dorsal aspect, with all four wings and body almost complete, including the faint but distinct left compound eye (the right is indistinct), and parts of three legs (Figs. 3–4). *not included in PCA, lacking too many characters. Family assignment and the dysagrionoid grade. The wings of MM-10752 and the FUM-N 13856 wing are consistent with all nine wing character states used in part for the Dysagrionidae diagnosis (Archibald et al. 2021), and Henriksen’s MGUH 1819 possesses those character states for the characters that are observable. These are (see Fig. 5, shown on the Dysagrion lakesii Scudder wing): 1- crossvein O absent; 2- arculus at or closely proximad Ax2; 3- quadrangle broad, distal side longer than proximal, posterior side longer than anterior, distal-posterior angle oblique, proximal-anterior angle usually about 90°; 4- nodus at least a quarter wing length, usually more; 5- AA, AP branch before joining CuP, AA briefly free distad petiole; 6- RP3-4 originates ca. one to usually two thirds the length from arculus to subnodus; 7- antesubnodal space without crossveins (note: Nel & Jouault (2022) mistakenly read this as antenodal space); 8- CuA–A space expanded in middle, at least two cells wide; 9- CuA long, ends on posterior margin at mid-wing or further These character states define the Dysagrionidae in combination with head character states of the suborder Cephalozygoptera (diagnosis of Archibald et al. 2021): width across eyes about twice the length from the anterior margin of antefrons to the posterior of the occiput; compound eyes more or less adpressed to head capsule, convex laterally but not hemispherical, their posterolateral corners extended posteriorly to varying degrees, sometimes even acutely; the distance between compound eyes at the level of the centre of the ocelli is about the width of one eye or less, i.e., the head is not shortened and distinctly extended laterally with bulging, hemispherical compound eyes as in Zygoptera. Archibald et al. missed that Rust (1999) had found that although the compound eyes are indistinctly preserved in Furagrion specimen 16-B3618, they are present and widely separated as in Zygoptera (“Von den grossen Komplexaugen sind nur undeutliche Reste überliefert. Sie liegen, wie für Zygopteren charakteristisch, weit voneinander getrennt an den Aussenseiten des Kopfes”, p. 19). He did not illustrate this specimen, and its whereabouts is not known to us. We examined several specimens that conform to Rust’s observation and, therefore, treat the genus as a zygopteran. The compound eyes are clearly preserved in 14M-A2163 (Fig. 6) and are faintly but confidently preserved in the proposed neotype MM-10752 (Fig. 3). These have the typical zygopteran shape, hemispherical, widely set and bulging outward, and the head is short. The compound eyes are not preserved in MM-10750 (Figs. 7–8), but the remaining head capsule is short and wide as in Zygoptera. Such a loss of eyes in fossils may happen, especially in Zygoptera, as they protrude and are more fragile, apparently more easily degraded than the robust head capsule, or they might simply break away from the head in death. Such missing compound eyes can also be clearly seen in multiple specimens of Lestes ceresti Nel & Papazian from the Oligocene of Céreste, France, cf. the holotype MNHN. F.R07445 (Archibald & Cannings 2021 fig. 1B and 1C) and PNRL 2019 and PNRL 2021 (Nel & Jouault 2022, figs 11A and 12; the head of L. ceresti PNRL 2020 in their fig. 11B appears too poorly preserved to confidently evaluate) and see Chalcolestes tibetensis Xia et al. (Xia et al. 2022, figs. 3A and 4) and Nel & Zheng

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