Introduction

Cylindrotomidae Schinner, 18631 together with Limoniidae Speiser, 19092, Pediciidae Osten-Sacken, 18603, and Tipulidae Latreille, 18024 sensu stricto are classified within Tipuloidea Latreille, 18024, group of insects present in the fossil record since at least 220 Ma (Triassic)5. With only 71 extant6 and 16 extinct species7, this smallest family within Tipuloidea is divided into two subfamilies Cylindrotominae, represented mainly in Holarctic Region, and Stibadocerinae with an example of vicariant distribution with a sister-group relationship between South American and East Asian taxa, supporting hypothesis an ‘ancestral’ trans-Pacific biota8.

According to phylogenetic synthesis based on combined morphological characters of adult, larvae and pupae, together with nuclear gene sequence data as 28S rDNA or CAD, the Cylindrotomidae are found as a sister group of Tipulidae (both being treated as subfamilies in Tipulidae in Ref.9. This group of insects is generally indicated as a sister group or being closely related to the Tipulidae by other authors10,11,12,13,14,15,16,17,18,19,20. But, within Cylindrotomidae21, only the representatives of subfamily Cylindrotominae are known from fossil record. The oldest described representatives of Cylindrotominae are only known from the Paleogene (56.0–47.8 Ma) by the extant genera Cylindrotoma Macquart, 183422 and Diogma Edwards, 193823,24,25,26,27,28,29,30,31,32,33, plus the extinct genus Cyttaromyia Scudder, 18777,34, while the oldest stem Tipulidae are Jurassic and the oldest crown Tipulidae are Cretaceous5,35,36,37. Thus, the Cylindrotomidae can be considered as a typical ghost lineage during the Mesozoic.

This phytophagous group of craneflies, which immatures lives among mosses and herbaceous plants.

The Cylindrotomidae (Supplementary Data S1) probably knew a period of diversification during the Eocene, sufficient to become frequent enough to be found as fossils. Most of the fossil Cylindrotomidae are know from the Middle Eocene Baltic amber31,32,38,39 and the Late Eocene Florissant Formation in USA24,39. Three species of Cylindrotoma are known from impressions of the Ypresian Fur Formation; two species from the Ølst Formation of Denmark were described within Cyttaromyia29 (Supplementary Table S1). Four species of Cyttaromyia were described from the Eocene Green River Formation USA, the other were described from Florissant Formation and Kishenehn Formation in USA, Middle Salt Formation in Alsace (France), Biamo Formation in Russia, and from Baltic amber24,27,28,30,31,40. Here we propose a morphological phylogenetic analysis to define the relationships between extinct genus Cyttaromyia and the other taxa in the family. We also describe two new species of Cyttaromyia on the basis of new fossils from the same Formation, and new technics of research give us possibility to redescribe Cyttaromyia obdurescens Cockerell, 192427.

Results

Systematic paleontology


Order Diptera Linnaeus, 175842


Infraorder Tipulomorpha Latreille, 18024


Family Cylindrotomidae Schinner, 18631


Subfamily Cylindrotominae Schinner, 18631


Genus Cyttaromyia


Type species: Cyttaromyia fenestrate Scudder, 187734, by monotypy.


Key to species of the genus Cyttaromyia Scudder, 187734

  1. 1.

    Wings without distinct patterning………………..………………………….…...…...………………………3.

    • Distinct patterns of coloration on wings………………..………………………….…...…...…………2.

  2. 2.

    Rs longer than R2+3+4 and R3+4 combined………………..………………………….…...…...Cyttaromyia vahldieki Freiwald, 199129

                                                                                                                                                                                                                                                                 Denmark/Ølst Formation

    • Rs shorter than R2+3+4 and R3+4 combined………………..………………………….…...…...Cyttaromyia rayona Freiwald & Krzemiński, 199130

                                                                                                                                                                                                                                                                  Russia/Biamo Formation

  1. 3.

    Wings hyaline………………..………………………….…...…...…………………………………………………………4.

    • Wings pale brownish without conspicuous markings with end of marginal cell apically somewhat clouded (Cockerell, 1924)………………..………………………….…...…...Cyttaromyia reclusa Cockerell, 192426

                                                                                                                                                                                                                        USA/Green River Formation/Roan Moutains/Colorado

  1. 4.

    Vein R1 well-developed………………..………………………….…...…...………………………………5.

    • Vein R1 reduced………………..………………………….…...…...……………………………………7.

  2. 5.

    Crossvein m-cu situated beyond bifurcation of Mb on M1+2 and M3+4; Sc terminating in C far beyond fork of Rs………………..………………………….…...…...……………………………………………………6.

    • Crossvein m-cu situated at bifurcation of Mb on M1+2 and M3+4; Sc terminating in C just beyond fork of Rs………………..………………………….…...…...Cyttaromyia gelhausi sp. nov.

                                                                                                                                                                                                                                                      USA/Green River Formation

  1. 6.

    Crossvein sc-r one of its length before tip of Sc; A1 tip before tip of Sc level………………..………………………….…...…...Cyttaromyia obdurescens Cockerell, 192527

                                                                                                                                                                                                                       USA/Green River Formation/Roan Moutains/Colorado

    • Crossvein sc-r at least two of its length before tip of Sc; A1 tip beyond e tip of Sc level………………..………………………….…...…...Cyttaromyia princetoniana Scudder, 189424

                                                                                                                                                                                                                                                               USA/Green River Formation

  1. 7.

    Sc elongate, terminating in C well beyond level of fork of Rs………………..………………………….…...…...8.

    • Sc short, terminating in C before level of fork of Rs………………..………………………….…...…...……………Cyttaromyia freiwaldi sp. nov.

                                                                                                                                                                                                                                                        USA/Green River Formation

  1. 8.

    Crossvein m-cu situated at most or before fork of Mb on M1+2 and M3+4…9.

    • Crossvein m-cu situated beyond fork of Mb on M1+2 and M3+4………………..………………………….…...…...Cyttaromyia frelloi Krzemiński, 199831

                                                                                                                                                                                                                                                                                       Baltic amber

  1. 9.

    Vein r–r (R2) terminating before level of r′–m′, before level of m–m………………..………………………….10.

    • Vein r–r (R2) terminating at level of r′–m′, behind level of m–m………………..………………………….…...…...Cyttaromyia fenestrata Scudder, 187734

                                                                                                                                                                                                                                                        USA/Green River Formation

  1. 10.

    d′-cell as long as d-cell or shorter………………..………………………….…...…...……………11.

    • d′-cell longer tan d-cell………………..………………………….…...…...…………………………………12.

  2. 11.

    M3+4 bifurcation on M3 and M4 approximately at level of m-m; d-cell 2× as long as M4; m-m beyond level of tip of r–r (R2)………………..………………………….…...…...Cyttaromyia lynnae De Jong, 201940

                                                                                                                                                                                                                                                               USA/Kishenehn Formation.

    • M3+4 bifurcation on M3 and M4 before level of m–m; d-cell 1.5× as long as M4; m–m approximately at level of tip of r–r (R2)………………..………………………….…...…...Cyttaromyia fuscula Cockerell, 192125.

                                                                                                                                                                                                                                                      USA/Green River Formation

  1. 12.

    Fork of Mb at level of fork of Rs; d′-cell narrowed at base………………..………………………….…...…...Cyttaromyia quievreuxi Séguy, 193428

                                                                                                                                                                                                                                              Alsace, France/Middle Salt Formation.

    • Fork of Mb before level of fork of Rs; d′-cell narrow, but not narrowed at base………………..………………………….…..13.

  1. 13.

                                                                                                                                                                                                                                              Tip of r–r (R2) beyond level of tip of fork of M3 +4 on M3 and M4; Rs at 2× as long as R2+3+4………………..………………………….…...…...Cyttaromyia scudderi Freiwald, 199129

                                                                                                                                                                                                                                                          Denmark/Ølst Formation

    • Tip of r–r (R2) before level of tip of fork of M3 +4 on M3 and M4; Rs at approximately as long as R2+3+4………………..………………………….…...…...Cyttaromyia rossi Krzemiński, 201941

                                                                                                                                                                                                                                            UK/Isle of Wight/Bembridge Marls


Cyttaromyia obdurescens Cockerell, 192527

(Fig. 1).

Figure 1
figure 1

Cyttaromyia obdurescens Cockerell, 192527, holotype No. 26284 (AMNH) (female): (A) habitus, lateral view; (B) apex of wing; (C) head and thorax, enlarged lateral view; (D) haltera; (E) apex of wing, drawing; (F) wing; C. terminal part of abdomen with ovipositor visible. cp, capitellum, pd, pedicellus of haltera, oc, ocellus, ped, pedicellus, pr, pronotum.

Full size image

Material examined

Holotype No. 26284 (AMNH) (female); American Museum National History; Green River Formation USA, Eocene.

Emended diagnosis

Wing without color spots; Sc elongate, terminating in C well beyond level of fork of Rs, beyond r–m level but far before m–m and r′–m′ level; opposite approximately half the length of R2+3+4; vein r–r (R2) terminating far before r′–m′ and m–m level, at level of basal part of M3; R1 well-developed; R2+3+4 longer than half length of Rs; d′-cell longer than d-cell, narrowed at its base; crossvein m-cu positioned beyond fork of Mb on M1+2 and M3+4; apical section of M3 almost as long as d-cell; A1 tip positioned near apex of wing, far behind level of Mb bifurcation on M1+2 and M3+4, before r–m level.

Comparison

Cyttaromyia obdurescens differs from C. fenestrata, C. freiwaldi sp. nov., C. frelloi, C. fuscula, C. lynae, C. quievreuxi, C. scudderi, and C. vahldieki by a well-developed vein r–r (R2). Wing of C. obdurescens is without spot. C. rayona and C. vahldieki have different patterning of wings. In contrast to C. gelhausi sp. nov., crossvein m-cu is situated beyond Mb, while in C. gelhausi sp. nov., it is located at Mb bifurcation, in C. frelloi just before Mb bifurcation. In C. obdurescens, vein sc-r is located one of its length from tip of Sc, tip of A1 is located before tip of Sc, while in C. princetoniana vein sc-r is located at least two of its length before the tip of Sc, A1 tip is located beyond level of tip of Sc. In C. obdurescens crossvein m-cu is positioned beyond fork of Mb measured from base of wing, while in C. rossi, m-cu is distinctly before fork of Mb.

Cyttaromyia gelhausi sp. nov.

http://zoobank.org/urn: lsid:zoobank.org:act:9165E3D2-514B-4524-9F85-A9895CBF2A31.

(Figs. 2, 3).

Figure 2
figure 2

Cyttaromyia gelhausi sp. nov.: A.-C. No. MNHN.F.A71341 (18a, male) (holotype): (A) habitus, latero-ventral view; (B) head, ventral view; (C) hypopygium, ventral view; D. No. MNHN.F.A71341 (18c, female) (additional material), habitus, lateral view. oc, ocellus; ped, pedicellus; scp, scapus.

Full size image
Figure 3
figure 3

Cyttaromyia gelhausi sp. nov.: (A) No. MNHN.F.A71341 (18a, male) (holotype), wing; (B), C. No. MNHN.F.A71341 (18c, female) (additional material): (B) wing; (C) wing, drawing.

Full size image

Material examined

Holotype MNHN.F.A71341 (18a, male); additional material 18b, female; 18c, female (on the same slab with holotype); Muséum national d'Histoire naturelle (MNHN), Paris; Green River Formation USA, Eocene.

Etymology

The specific name is given to honor Doctor John Gelhaus (Academy of Natural Sciences of Drexel University), the eminent specialist on extinct and extant insects.

Diagnosis

Flagellomeres short and relatively wide; wing without color spots; Sc not very elongate, terminating in C just beyond level of fork of Rs, opposite level of crossvein r–m; opposite approximately 1/10 length of R2+3+4; vein r–r (R2) terminating far before r′–m′ and just before m–m level, at level of basal part of M3; R1 well-developed; R2+3+4 longer than half length of Rs; d′-cell longer than d-cell, narrowed at its base; crossvein m-cu positioned at fork of Mb on M1+2 and M3+4; apical section of M3 almost as long as d-cell.

Comparison

Cyttaromyia gelhausi sp. nov. has no distinct color patterning of the wings in contrast to C. vahldieki and C. rayona. The wing of C. reclusa is pale brownish without conspicuous markings26, but the end of the marginal cell and the veins bounding the discal cell apically are somewhat clouded. The body length of C. gelhausi sp. nov. is at most 6.83 mm, wing length 7 mm, while the body length of C. reclusa is 13.5 mm and wing length 12 mm. In C. gelhausi sp. nov. tibial spurs are absent while pattern of tibial spurs of C. frelloi is 1:1:231. Vein R1 is well-developed in C. gelhausi sp. nov., while in C. freiwaldi sp. nov., C. frelloi, C. fuscula, C. lynnae, C. quievreuxi, C. rossi, C. scudderi, C. vahldieki R1 is reduced. In C. gelhausi sp. nov. Sc is not very elongate, terminating in C just beyond level of fork of Rs, opposite the level of crossvein r-m, while in C. fenestrata, C. frelloi, C. fuscula, C. lynnae, C. obdurescens, C. princetoniana, C. quievreuxi, C. rayona, C. scudderi, and C. vahldieki, it is terminating far beyond level of Rs. In C. freiwaldi sp. nov. Sc terminating in C before Rs level. In C. fenestrata and C. vahldieki, Sc is very elongated, terminating in C opposite basal part of M3. Crossvein m-cu is positioned at fork of Mb on M1+2 and M3+4 while in other fossil species of the genus Cyttaromyia this vein is situated beyond fork of Mb; in C. frelloi this vein is located before fork of Mb. Moreover, in C. vahldieki and C. fenestrata vein r–r (R2) terminating in R3+4 beyond d′ level, far beyond the level of basal part of M3, in C. gelhausi sp. nov. this vein is terminating at the level of d’, at the level of basal part of M3.

Cyttaromyia freiwaldi sp. nov.

(Figs. 4, 5).

Figure 4
figure 4

Cyttaromyia freiwaldi sp. nov. No. MNHN.F.A71342 (70A, part, female), (holotype): (A) habitus, dorsal view; (B) head, dorsal view; (C) ovipositor, dorsal view, (D) wing venation, (E) wing venation, drawing.

Full size image
Figure 5
figure 5

Cyttaromyia freiwaldi sp. nov.: (A) No. MNHN.F.A71342 (68, counterpart, female), (holotype), habitus, dorsal view; B.-F. No. MNHN.F.A71342 (70AB, female), (additional material): (B) habitus, dorsal view; (C) head, dorsal view; (D) terminal part of abdomen with ovipositor visible, dorsal view; (E) left wing; (F) right wing. oc, ocelli; thx, thorax.

Full size image

http://zoobank.org/urn: lsid:zoobank.org:act:DB604450-AD47-4644-82E0-A33FEAEB7157.

Material examined

Holotype MNHN.F.A71342 (70A, part/68, counterpart, female), additional material 70B, female, on the same slab as holotype), Muséum national d'Histoire naturelle (MNHN), Paris; Green River Formation USA, Eocene.

Etymology

The new species is dedicated to the German eminent researcher Doctor Andre Freiwald (Institut für Paläontologie, Universität Erlangen).

Diagnosis

Wing without color spots; Sc short, terminating in C before level of fork of Rs, far before level of crossvein r–m; vein r–r (R2) terminating far before r′–m′ level and at m-m level, just beyond level of basal part of M3; R1 atrophied; R2+3+4 longer than half length of Rs; d′-cell shorter than d-cell, narrowed at its base; crossvein m-cu positioned beyond fork of Mb on M1+2 and M3+4; M3 shorter than d-cell.

Comparison

Cyttaromyia freiwaldi sp. nov. has no distinct patterning of the wings in contrast to C. vahldieki and C. rayona. In contrast to C. reclusa, the body length of C. freiwaldi sp. nov. is at most 4.8 mm, wing length 6.22 mm, while the body length of C. reclusa is 13.5 mm and wing is 12 mm long with the end of the marginal cell and the veins bounding the discal cell apically are somewhat clouded26. C. freiwaldi sp. nov. differs from other fossil species especially by point of termination of Sc. In C. freiwaldi sp. nov. vein Sc terminating in C before fork of Rs while in other fossil species, excluding C. reclusa27, Sc terminating in C just beyond or far beyond bifurcation of Rs. Moreover, in contrast to C. gelhausi sp. nov., C. obdurescens, C. princetoniana, and C. rayona, the vein R1 in C. freiwaldi sp. nov. is reduced. Vein r–r (R2) of C. freiwaldi is terminating in R3+4 at d-cell level while in C. fenestrata and C. rayona beyond this level, in C. vahldieki even beyond d`-cell level (Supplementary Data S2).

Phylogenetic position of Cyttaromyia within Cylindrotomidae

The parsimony analysis yielded three equally most parsimonious cladograms, 53 steps long, with consistency index CI = 62, RI = 66. Their consensus majority rule cladogram is shown in Fig. 6A. The Cylindrotomidae clade is supported by six synapomorphies: presence of petiole (character 15, state 0), relationship of R3 and R4 (character 17, state 1), position of crossvein m-cu relative to the bifurcation of M3+4 (character 18, state 1), shape of d-cell (character 20, state 1), position of tip of A2 (character 25, state 0), morphology of aedeagus (character 28, state 2). Cyttaromyia is supported on consensus tree by the ‘presence of supernumerary crossvein connecting vein R4+5 with M1 near its origin, to produce two discal cells’ (character 16, state 1). The clade (Cylindrotominae + Stibadocerinae (Hennig, 1973)43) is supported by two synapomorphies, relationship of M1 and M2 (character 14, state 1), position of tip of A2 (character 26, state 0). The clade [Phalacrocera replicata Linnaeus, 175841 + (Liogma nodicornis Osten Sacken, 186544 + Triogma trisculata Shummel, 182945)] is supported by one synapomorphy, viz. position of crossvein m-cu relative to the bifurcation of Mb (character 19, state 1). Triogma trisculata appears as the sister-group to Liogma nodicornis, the clade (Liogma nodicornis + Triogma trisculata) being supported by three synapomorphies: shape of flagellomeres (character 2, state 1), position of R5 (character 13, state 1), degree of reduction of crossvein r–m (character 24, state 1). The clade Stibadocerinae [= (Stibadocerodes australiensis Alexander, 192246 + (Stibadocera bullans Enderlein, 191247) + (Stibadocerella pristina Brunetti, 191848 + Stibadocerina chilensis Alexander, 192849)))] is supported by two synapomorphies: the number of branches of Rs reaching wing margin (character 9, state 1), relationship of R3 and R4 (character 17, state 2) (Supplementary Data S3).

Figure 6
figure 6

(A) Consensus relationships tree of genera of subfamily Cylindrotominae. Filled circles indicate synapomorphies or autapomorphies; open circles indicate plesiomorphies. Number of character given above circles, states of characters below circles; (B) Wing venation of fossil Cylindrotominae with chronostratigraphic distribution view; (C) Wing venations of representatives of genera: Cylindrotoma, Cyttaromyia, Diogma, represented in fossil record. Wing venation redrawing24,25,27,28,29,31,34,42,50. Stratigraphic chart according to International Stratigraphic Chart, International Commission of Stratigraphy (v. 2021/05) https://stratigraphy.org/chart.

Full size image

Discussion

The subfamily Cylindrotominae21 currently contains more species and genera, compared to the Stibadocerinae. The oldest record of the extinct genus Cyttaromyia is Paleogene, as for the genus Cylindrotoma. The fossil record of the Cylindrotominae dated back to at least 56.0 Ma29, with no evidences on older occurrences. Other representatives of Cylindrotominae are known in the Eocene24,25,27,28,31,32,38, but most of them are strictly modern6 (Supplementary Figs. S1, S2).

According to our parsimony analysis (consensus tree), Cyttaromyia falls as sister group of all the extant genera of Cylindrotomidae, and thus belongs to the stem group of the family, and could correspond to a different subfamily. Also, the extant Cylindrotominae appear paraphyletic in respect to the Stibadocerinae because the two genera Cylindrotoma and Diogma fall in an unresolved polytomy with this subfamily plus a clade that contains the other cylindrotomine genera. Nevertheless, these results are preliminary and would need to be completed by the addition of characters, in particular molecular.

The Cylindrotominae (and also Cyttaromyia) have a Holarctic distribution, while the Stibadocerinae have a more disjunctive distribution in Indo-Malaysia, Australo-Papua and Southern Neotropics (Taiwan, China, Indonesia, Malaysia, India, Papua New Guinea, Philippines, Australia, and Chile). Such distribution resembles that of an ancient Gondwana group, with ‘relic’ taxa in Australia and Chile; but the present phylogenetic analysis would contradict this hypothesis, as the only known stem representative of the family is also Holarctic. Further analyses together with discoveries of fossil Cylindrotomidae in the Southern Hemisphere shall be necessary to clarify this complex, strange situation.

From a taxonomic point of view, Architipula is characterized by the occurrence of vein Sc tip beyond fork of Rs level, subequal to or a little shorter than veins R2+3 and R3 combined, distinctly inclined crossvein m-m between M1+2 and M3, usually short and straight vein A251 Cyttaromyia is characterized by the occurrence of two discal cells (d-cell and d′-cell), supernumerary crossvein r′–m′ connecting vein R5 with M1 near its origin, to produce two discal cells. Some similarities are present in the wing venations of Cyttaromyia and Cylindrotoma: separate M1 and M2 and relatively long vein M1. In Cylindrotoma the crossvein r′–m′ is atrophied, but the base of vein M1 is strongly arched and only one discal cell (d-cell) is present. In all other Cylindrotominae, like Diogma (recorded from the Middle Eocene)32, or other genera with a younger fossil record, the crossvein r′–m′ is reduced and only one discal cell (d-cell) is present (Fig. 6B,C; Supplementary Figs. S3, S4).

Conclusion

The revision of Cyttaromyia obdurescens and the description of two new species Cyttaromyia gelhausi sp. nov. and Cyttaromyia freiwaldi sp. nov., allowed us to propose a key to the species of this genus. We have also made the first morphological phylogenetic analysis of the Cylindrotomidae, with in the rather surprising result of the putative paraphyly of the Cylindrotominae and a position of Cyttaromyia in the stem group of this family.

Material and methods

The study was based on material from the collection of the Muséum national d'Histoire naturelle (MNHN), Paris (five specimens) and American Museum National History (AMNH) (one specimen). The imprints from sediments of Green River Formation USA (age 50.3–46.2 Ma42) were studied using a Nikon SMZ 1500 stereomicroscope equipped with a Nikon DS–Fi1 camera in University of Rzeszów. The microphotographs and measurements were taken with NIS–Elements D 3.0 software. Drawings were completed by tracing the photographs, nomenclature of wing venation was used31.

The Eocene Green River Formation USA (50.3–46.2 Ma) (Rocky Mountains, Colorado, Wyoming, Utah) is one of the most famous Eocene palaeontological sites of the World. The sediments include mainly calcium carbonate, calcite and aragonite. The occurrence of different types of sludge varies with the geological levels. Tipton Shale Member in Greater Green River Basin is the oldest rock formation of the Green River52.

Placement of the genus Cyttaromyia within Cylindrotomidae was tested with the use of Maximum Parsimony (MP) criterion, implemented in TNT 1.5 software package, with the ‘Traditional Search’ options53,54, with memory to store 99,999 trees, 10,000 replications, with 100 trees to save per replication; utilizing tree-bisection-reconnection (TBR) algorithm and collapsing zero length branches. The type species of extinct and extant genera of family Cylindrotomidae were included in the analysis. Architipula seebachi (Geinitz, 1884)55—type species of the genus Architipula Handlirsch, 190656, was selected as outgroup because the Architipulinae are closely related to Cylindrotominae. Tipula oleracea Linnaeus, 175841 was used as a type species of the genus Tipula, in the family Tipulidae, currently considered as the sister family of the Cylindrotomidae. The morphological data to the matrix were compiled in the Nexus file using Mesquite v. 3.61 build 92757. All 28 characters of the imagines used in the analysis were treated as unordered and unweighted (Supplementary Table S2). Equal weighting analysis (EW) was performed53; the trees received were viewed and their features studied using WinClada 1.00.08 and ASADO 1.61, with Unambigous Changes Only, Fast Optimization (ACCTRAN) and Slow Optimization (DELTRAN) options57,58,59. Tree files received were adjusted using Corel Draw X3 and Photo-Paint Software. The 28 morphological characters of the imago observed in the fossil and recent material and used for analysis are listed below. The data matrix given is partly based on used morphological features8,21,34,41,43,44,45,50,56.