The crane-fly genus Dicranomyia is well represented amongst fossil Diptera. To date, over 40 fossil species of this genus have been described. The extinct representatives of Dicranomyia are known from different ages (mainly from the Eocene, but also from younger epochs such as the Oligocene or Miocene) and from different parts of the world.
The oldest representatives of the genus Dicranomyia are known from the earliest Eocene Mo Clay of Denmark (Henriksen Reference Henriksen1922; Krzemiński Reference Krzemiński2001). Fourteen species are known from late Eocene Baltic amber (Meunier Reference Meunier1899, Reference Meunier1906, Reference Meunier1916; Alexander Reference Alexander1931; Savchenko Reference Savchenko1967; Krzemiński Reference Krzemiński2000b; Kania et al. Reference Kania, Krzemiński and Penar2013; Kania Reference Kania2014; Krzemiński et al. Reference Krzemiński, Kania and Durak2015). A further 15 species of this genus from this epoch are preserved as compression fossils: four from the Green River Formation, USA (Scudder Reference Scudder1877; Cockerell Reference Cockerell1908); three from the latest Eocene Bembridge Marls of England (Cockerell & Haines Reference Cockerell and Haines1921; Cockerell Reference Cockerell1922); and eight from Florissant, USA (Scudder Reference Scudder1894) (Table 1).
Table 1 List of fossils belonging to the genus Dicranomyia, known from the Eocene (age given after Grimaldi & Ross (Reference Grimaldi, Ross, Fraser and Sues2017)).
Two species of Dicranomyia are known from the Oligocene: one from the Oligocene of France (Dicranomyia antennifera Théobald, Reference Théobald1937) and one from Russia (Krzemiński Reference Krzemiński2000a).
Seven species are known from the Miocene: Dicranomyia alexbrowni Podenas & Poinar, Reference Podenas and Poinar2012, Dicranomyia chiapa Podenas & Poinar, Reference Podenas and Poinar2012, Dicranomyia mexa Podenas & Poinar, Reference Podenas and Poinar2012 and Dicranomyia vella Podenas & Poinar, Reference Podenas and Poinar2012 from Mexico; Dicranomyia fera Podenas & Poinar, Reference Podenas and Poinar1999 and Dicranomyia lema Podenas & Poinar, Reference Podenas and Poinar1999 from the Dominican Republic; and Dicranomyia sergio Krzemiński & Gentlini, Reference Krzemiński and Gentlini1992 from Italy.
Representatives of four subgenera of Dicranomyia have been recorded in Baltic amber. The most common amongst Baltic amber inclusions are representatives of the subgenus Dicranomyia, also the most numerous species in Recent fauna. The representatives of other subgenera are rare in Baltic amber, represented only by single species: Dicranomyia (Melanolimonia) krzeminskii Kania, Reference Kania2014 and Dicranomyia (Sivalimnobia) herczeki Krzemiński & Kania, Reference Krzemiński, Kania and Durak2015 (in Krzemiński et al. Reference Krzemiński, Kania and Durak2015).
The newly described species is the second representative of the subgenus Melanolimonia in Baltic amber.
1. Material and methods
This study is based on material from the collection of the Institute of Systematic and Evolution of Animals, Polish Academy of Sciences (ISEA PAS) (one specimen; male). The specimen was studied using a Nikon SMZ 1500 stereomicroscope. Photomicrographs were taken with a Nikon DS-Fi1 camera equipped with a microscope. Drawings were made from specimens and photographs. Measurements were taken with NIS-Elements D 3.0 software. The length of the discal cell was measured from the hind edge of the discal cell to the connection of cross-vein m–m with vein M3. M3 was measured from the connection of cross-vein m–m with vein M3 to the edge of the wing (Kania Reference Kania2014). The term “d-cell base” is used after Krzemiński Reference Krzemiński1993. The drawings were made by IK.
2. Systematic palaeontology
Order: Diptera Linnaeus, Reference Linnaeus1758 Family: Limoniidae Speiser, Reference Speiser1909 Genus: Dicranomyia Stephens, Reference Stephens1829 Subgenus Melanolimonia Alexander, Reference Alexander1964
Type species. Tipula moria Fabricius, Reference Fabricius1787 (original designation).
Dicranomyia (Melanolimonia) kukulai sp. nov. (Figs 1A–B, 2A–C, 3A–B)
Figure 1 Dicranomyia (M.) kukulai sp. nov., MP/3555 (male), ISEA PAS, holotype: (A) gonocoxite and gonostyles, dorsal view, reconstruction; (B) wing venation. Abbreviations: A1, A2 = anal veins; C = costa; Cu = cubitus; d = discal cell; gx = gonocoxite; h = humerus; ing = inner gonostylus; M1+2 –M4 = media; Mb = medio-basal vein; m–cu = media–cubital cross-vein; oug = outer gonostylus; r = rostral prolongation of ventral gonostylus (rostrum); R1–R5 = radius; Rs = sector radii; Sc = subcosta; ss = spines.
Figure 2 Dicranomyia (Melanolimonia) kukulai sp. nov., MP/3555 (male), ISEA PAS, holotype: (A) latero-dorsal view; (B) wing. Abbreviations: A1, A2 = anal veins; C = costa; Cu = cubitus; d = discal cell; M1+2, M3 = media; Mb = medio-basal vein; m–cu = media–cubital cross-vein; R3+4, R5 = radius; Rs = sector radii.
Figure 3 Dicranomyia (Melanolimonia) kukulai sp. nov., MP/3555 (male), ISEA PAS, holotype: (A) hypopygium, dorsal view; (B) gonocoxite, gonostyles. Abbreviations: gx = gonocoxite; ing = inner gonostylus; oug = outer gonostylus; r = rostral prolongation of ventral gonostylus (rostrum); ss = spines.
Diagnosis. Two short spines on rostral prolongation on inner gonostylus, the first one half the length of the second, inner gonostylus very wide, massive with two wide processes almost black in one third distal of its length; outer gonostylus narrow and hooked; vein Sc elongated, ending behind half the length of Rs, cross-vein m–cu behind the fork of Mb, in one fifth of d-cell base from bifurcation of Mb; M3 one fifth shorter than length of d-cell; Rs bifurcation before fork of Mb.
Etymology. The specific name is dedicated to Professor Krzysztof Kukuła (Department of Environmental Biology, University of Rzeszów), the eminent biologist, ecologist and specialist on ichthyofauna.
Material examined. Holotype, male. No. MP/3555, Coll. Institute of Systematic and Evolution of Animals, Polish Academy of Sciences, Kraków, Poland.
Description. Body dark brown, with almost black part of hypopygium, 5.8 mm long (Fig. 2A).
Head not large, with huge eyes; antenna not well visible with elongated, cylindrical flagellomeres, first flagellomeres about 0.1 mm long; palpus 4-segmented; the last palpal segment cylindrical and elongated.
Thorax. (Fig. 2A) Wing (Figs 1B, 2A, B) 6.5 mm long, 1.8 mm wide; without spots, pterostigma not visible; vein Sc ending behind half the length of Rs, opposite one fourth of Rs; vein R5 approximately twice longer than vein Rs; M3 very short, one fifth shorter than d-cell; d-cell very elongated, twice as long as wide, vein M1+2 one fifth longer than d-cell; cross-vein m–cu almost straight, behind the bifurcation of Mb, situated in one fifth of d-cell base from bifurcation of Mb; A1 and A2 elongated, almost straight.
Abdomen. Hypopygium (Figs 1A, 2A, 3A, B): 0.9 mm long, 0.8 mm wide, gonocoxite 0.4 mm long, comparatively narrow, approximately twice as long as wide, with elongated and strong setae, two short spines on rostral prolongation of inner gonostylus, the first one half the length of the second, inner gonostylus very wide, massive, with two wide processes almost black in one thirds distal of its length; outer gonostylus 0.4 mm long, narrow and hooked.
Comparisons. A newly described species is classified to the subgenus Melanolimonia. Previously, only one species of this subgenus was known from Baltic amber: Dicranomyia (Melanolimonia) krzeminskii Kania, Reference Kania2014. The other species known from Baltic amber belong to other subgenera (Dicranomyia, Sivalimnobia), or are unclassified to a subgenus. In the new species, the inner gonostylus is very wide, with two very wide processes, the outer gonostylus is narrow and hooked. Part of the hypopygium is almost black. In comparison, in D. (M.) krzeminskii, the gonocoxite is equal in length to inner gonostylus and two short spines occur on the inner gonostylus. Vein Sc ends opposite approximately half the length of Rs and cross-vein m–cu is straight, situated slightly before the fork of Mb. In D. (M.) kukulai sp. nov., cross-vein m–cu is almost straight, situated in one fifth proximal of d-cell base, vein Sc ends behind half the length of Rs and M3 is very short, shorter than the length of the d-cell; whereas in D. (M.) krzeminskii the d-cell is short and vein M3 is distinctly longer than the discal cell.
These features – an almost black body colour, wing venation with a very elongated vein Sc and the morphology of the hypopygium – enable the classification of the new species to the subgenus Melanolimonia and differentiate it from other species classified to the subgenera Dicranomyia or Sivalimnobia known from Baltic amber.
However, we can see some additional differences in the morphology of the hypopygium, and in the wing venation. In contrast to Dicranomyia (D.) gorskii Kania, Krzemiński & Penar, Reference Kania, Krzemiński and Penar2013, Dicranomyia (D.) ewa Kania, Reference Kania2014 and Dicranomyia (D.) lobata Meunier, Reference Meunier1906, in which there existed a single spine on the rostral prolongation of the inner gonostylus, in D. (M.) kukulai sp. nov. there are definitely two, not very elongated, with the first one half the length of the second. In D. (D.) gorskii and D. (D.) ewa, this spine is very elongated and strong, reaching half the length of the gonostylus. Dicranomyia (D.) perpendicularis Savchenko, Reference Savchenko1967 and Dicranomyia (D.) succinica Kania, Reference Kania2014 are characterised by two spines on the rostral prolongation of the ventral gonostylus, but these structures are very elongated and strong in these species. In Dicranomyia (D.) kalandyki Krzemiński, Reference Krzemiński2000b, there are three spines of comparable length on rostral prolongation of the inner gonostylus. Moreover, in D. sinuata Meunier, Reference Meunier1916, cross-vein m–cu is slightly sinuous, but in D. (M.) kukulai sp. nov., this vein is strong.
The newly described species also differs in wing venation from Dicranomyia (D.) alexandri Kania, Reference Kania, Krzemiński and Penar2013 (in Kania et al. Reference Kania, Krzemiński and Penar2013), Dicranomyia (D.) graciosa Meunier, Reference Meunier1916, Dicranomyia (D.) grandis Meunier, Reference Meunier1899, D. (D.) kalandyki, D. (D.) lobata, D. (D.) perpendicularis, D. (D.) sinuata and D. (D.) succinica, in which vein Sc is very short, ending close to the Rs origin, before the mid-length of Rs or at half the vein sector radii; whilst in the newly described species it is longer.
The cross-vein m–cu is situated before the fork of Mb in Dicranomyia (D.) baltica Kania, Reference Kania2014, D. (D.) lobata and D. (D.) perpendicularis and at the bifurcation in D. (D.) alexandri (at or just behind), D. (D.) gorskii, D. (D.) kalandyki, D. (D.) meunieri and D. (D.) sinuata; whilst in the newly described species this vein is situated distinctly behind the fork of Mb. In the new species, the d-cell is very elongated and M3 is very short, one fifth shorter than the d-cell in D. (D.) alexandri, D. (D.) baltica, D. (D.) ewa, D. (D.) gorskii, D. (D.) graciosa, D. (D.) grandis, D. (D.) lobata, D. (D.) meunieri, D. (D.) perpendicularis and D. (D.) sinuata. In D. (M.) krzeminskii, this vein is equal in length or longer.
There are also the differences between the new species and species known from the Priabonian from Florissant. Dicranomyia longipes, described by Scudder (Reference Scudder1894), is a large species with length of wing about 7 mm and discal cell closed, but much narrower apically than at the base by the length of the third posterior cell. In the newly described species, the d-cell is not narrowed. In D. longipes and D. stagnorum Scudder, Reference Scudder1894, the distal part of the marginal cell, according to Scudder, is almost as long as the proximal. In D. inferna Scudder, Reference Scudder1894, D. fragilis Scudder, 1894, D. stigmosa Scudder, Reference Scudder1894, D. primitiva Scudder, Reference Scudder1894, D. fontainei Scudder, Reference Scudder1894 and D. rostrata Scudder, Reference Scudder1894, the distal part of the marginal cell is much shorter than the proximal; in the new species it is longer. In D. stagnorum, the d-cell is opened, whilst the d-cell is closed in the new species.
In D. exhumata Cockerell, Reference Cockerell1922 and D. thybotica Henriksen, Reference Henriksen1922, cross-vein m–cu is situated at fork of Mb or just before, M1+2 and M3 are much longer than the d-cell and the Rs bifurcation is opposite the fork of Mb; but in the new species, cross-vein m–cu is situated behind the fork of Mb and M1+2 and M3 are shorter in comparison to the length of the d-cell. The fork of Rs in D. thybotica and D. freivaldi Krzemiński, Reference Krzemiński2001 is opposite the fork of Mb; but in the new species, it is distinctly before. Cross-vein m–cu in D. speciosa Krzemiński, Reference Krzemiński2001 and D. freiwaldi is situated before the fork of Mb; in D. bellissima Krzemiński, Reference Krzemiński2001 it is situated at the fork of Mb. In these species, vein M3 is longer than the d-cell; in the newly described species this vein is positioned after the bifurcation of Mb and M3, and is shorter than the d-cell. Moreover, in D. bellissima, vein Sc is very short, ending just behind the origin of the sector radii, but it is longer in the new species. In D. freiwaldi, the distal part of the wing is covered by numerous microtrichia; but microtrichia on the wing does not occur in new species.
D. rhodolitha Cockerell, Reference Cockerell1908 is characterised by the occurrence of small dark spots on the costa, 2.6 mm and 4 mm from the base. The wing of the newly described species is pale, without spots.
A similar morphology of the hypopygium can be found amongst some Recent species of the subgenus Melanolimonia, such as D. (M.) fulvonigrina Alexander, Reference Alexander1965, where there occur two, not very large, spines on the rostral prolongation on the inner gonostylus; but the position of these spines is not the same as those in to D. kukulai sp. nov.
Age and occurrence. Eocene, Baltic amber.
Remarks. According to Ritzkowski (Reference Ritzkowski1997) and Perkovsky et al. (Reference Perkovsky, Rasnitsyn, Vlaskin and Taraschuk2007), Baltic amber has been dated to 38–47 Ma. As Wappler (Reference Wappler2003, Reference Wappler2005) suggests, based on analyses of glauconites from the Sambia Peninsula which showed that the ‘blue earth' formation (amber-bearing Prussian Formation) can be allocated to the Middle Eocene, the Baltic amber can be dated to 44.1±1.1 Ma (Lutetian). Similarly, Weitschat & Wichard (Reference Weitschat, Wichard and Penney2010) suggested an older age for the Baltic amber. A Middle Eocene (or older) age of Baltic amber was argued by Perkovsky et al. (Reference Perkovsky, Rasnitsyn, Vlaskin and Taraschuk2007); he suggested that the age of Baltic amber should be estimated as Late Eocene (Bartonian/Priabonian: 37.7±3 Ma). The age of Baltic amber is debatable. However, according to the latest information of Grimaldi & Ross (Reference Grimaldi, Ross, Fraser and Sues2017), a Priabonian (Upper Eocene) age is most likely for this kind of fossil resin.
3. Conclusions
Whilst the genus Dicranomyia comprises ca.1,300 species and is distributed worldwide, the representatives of the subgenus Melanolimonia are not so numerous in species and occur only in the Palaearctic (west Palaearctic: 15 species; east Palaearctic: 16 species), Oriental (19 species) and Nearctic (four species) regions (Oosterbroek Reference Oosterbroek2016).
Amongst the known fossils, representatives of this subgenus are extremely rare (Evenhuis Reference Krzemiński, Kania and Durak2015). Until now, only one species has been described from the fossil record (by Kania Reference Kania2014). A new species, which is characterised by an almost black part of the hypopygium, is the second representative of this subgenus amongst inclusions in Baltic amber. The subgenus Melanolimonia is characterised by having a generally black colouration, a rarely brown or polished fulvous, pleura extensively silvery pruinose, with a very broad anterior vertex and width approximately four times the diameter of the antennal scape. The last segment of the antenna in the representatives of Melanolimonia is usually elongated and more-or-less constricted at near mid-length. The subcostal vein (Sc) in this subgenus is very long, ending approximately opposite half the length of Rs or longer; the discal cell is closed. The tergite of the male hypopygium ranges in shape from almost truncate at the posterior border, without evident lobes, to profoundly emarginate, forming slender finger-like lobes (Alexander Reference Alexander1964). The outer gonostylus is a simple, curved sickle, hooked with an acute tip, as in D. (M.) kukulai sp. nov. The aedeagus is usually conspicuously expanded and abundant scabrous points with setae occur at the outer end of this structure.
The representatives of the subgenus Melanolimonia currently occur only in the Northern Hemisphere, as its presence has not been noted in Australian, Oceanian, Afrotropic or Neotropic regions. We have no data regarding the occurrence of the extinct and extant representatives of Melanolimonia from the Southern Hemisphere. The other representatives of Dicranomyia, known from the Eocene, come from Europe and North America. The oldest Eocene representatives of Dicranomyia are known from the Early Eocene (Ypresian) of Europe (four species), and also from North America – from the USA (Ypresian\Lutetian border). Many more species known from latest Eocene (Priabonian), are mainly from Europe, as well as from North America (Table 1).
4. Acknowledgements
We are deeply indebted to Dr. Andrew Ross and an anonymous reviewer for their valuable comments and remarks on this manuscript.
