Two new species of Tasiocera Skuse from Baltic amber (Diptera, Limoniidae)

The paper presents very rare fossil record of crane flies. Inclusions in Baltic amber have documented the second evidence of the existence of the genus Tasiocera (Diptera: Limoniidae: Chioneinae) in ancient epochs of Earth’s history. Hypotheses were also introduced regarding the environmental preferences of fossil Dasymolopilus in relation to modern representatives of the subgenus. The genus is numerous in species and widespread in the modern fauna, while only one species, Tasiocera (Dasymolophilus) circumcincta, has been known from the fossil record to date. The paper presents an additional description and graphic documentation of this species based on new materials. The discovery of two other species Tasiocera (Dasymolophilus) gorskii sp. nov. and Tasiocera (Dasymolophilus) baltica sp. nov. in Eocene resins documents the occurence of Tasiocera since Eocene. Interestingly, only subgenus Dasymolophilus is represented both in extinct and extant fauna while subgenus Tasiocera is not known from the fossil record. The new discovery is very significant, and the result of the study adds a brick to our understanding of the evolution of this group of insects and their habitat.

The paper presents very rare fossil record of crane flies.Inclusions in Baltic amber have documented the second evidence of the existence of the genus Tasiocera (Diptera: Limoniidae: Chioneinae) in ancient epochs of Earth's history.Hypotheses were also introduced regarding the environmental preferences of fossil Dasymolopilus in relation to modern representatives of the subgenus.The genus is numerous in species and widespread in the modern fauna, while only one species, Tasiocera (Dasymolophilus) circumcincta, has been known from the fossil record to date.The paper presents an additional description and graphic documentation of this species based on new materials.The discovery of two other species Tasiocera (Dasymolophilus) gorskii sp.nov.and Tasiocera (Dasymolophilus) baltica sp.nov. in Eocene resins documents the occurence of Tasiocera since Eocene.Interestingly, only subgenus Dasymolophilus is represented both in extinct and extant fauna while subgenus Tasiocera is not known from the fossil record.The new discovery is very significant, and the result of the study adds a brick to our understanding of the evolution of this group of insects and their habitat.
Subfamily Chioneinae Rondani 1 (= Eriopterinae van der Wulp 2 ; see Starý 3 ) is represented in recent fauna by 60 genera, 81 subgenera and over 4400 species 4 .It is the largest subfamily of Limoniidae in respect of the numer of species.The oldest representative of Chioneinae is Gonomyia (Azaria) libanensis Kania, Krzemiński and Krzemińska 5 .The holotype of this species was found in Hammana-Mdeyrij outcrop, Caza (District) Baabda, Mouhafazet Jabal Loubnan (Governorate Mount Lebanon), Central Lebanon and it is dated on Early Cretaceous, ante-Barremian 6 .From Cretaceous period are known also the other Chioneinae, the representatives of Rhabdomastix Skuse 7 , subgenus Myanmamastix Kania-Kłosok, Jordan-Stasiło, Kopeć, Janiszewska & Krzemiński 8 , preserved in Myanmar amber dated on Upper Cretaceous ca.98.79 ± 0.62 Ma.Most of the Chioneinae known from the fossil record have been preserved in Eocene Baltic amber, such as representatives of Cheilotrichia Rossi 9 or Ormosia Rondani 10 .Few species are known from the younger periods of the Oligocene of Germany, such as Erioptera Meigen 11 or from the Miocene, such as Styringomyia Loew 12 (Miocene Italy) or Molophilus Curtis 13 (Dominican amber).
The genus Tasiocera Skuse 7 is very rare in fossil record.Only one species belonging to the genus has been described so far, Tasiocera (Dasymolophilus) circumcincta Meunier 14 .The species abundance of the modern fauna of the genus does not correspond to that known from the fossil record.In recent fauna two subgenera are represented within the genus Tasiocera-Tasiocera Skuse 7 (with 40 recent species) and Dasymolophilus Goetghebuer 15 (35 recent species).The representatives of the subgenus Tasiocera are found only in Australia and New Zealand.In the case of the subgenus Dasymolophilus a wider range is noted, with a large number of species occuring in the Ethiopian and Palearctic zoogeographical regions 4 (Table 1).
Crane flies belonging to the subgenus Dasymolophilus are characterized by elongated flagellomeres of antennae, the wings are rather narrow, covered with long and dense setae, both on the wing edges and along the internal veins.The cubital and medial veins are costalized in the distal part of the wing and are divided, the anal vein A 2 is shortened, and the discal cell (d-cell) is usually open.The gonostyles are often elongate, and the aedeagus complex can vary greatly between species, but is often asymmetric 17 and the postnotum bristles are present in the representatives of the Dasymolophilus group 18 .
The classification of the subgenus Dasymolophilus has changed, the subgenus Dasymolophilus was originally included in the genus Molophilus.Alexander 19 and Edwards 20 showed a closer relationship of this taxon to the genus Tasiocera based on differences in morphology.Characteristics such as the different structure of gonostylus than in Molophilus, and the presence of postnotum bristles in the representatives of the subgenus Dasymolophilus

Nomenclatural acts
The electronic edition of this article conforms to the requirements of the amended International Code of Zoological Nomenclature, and hence the new names contained herein are available under that Code from the electronic edition of this article.This published work and the nomenclatural acts it contains have been registered in ZooBank, the online registration system for the ICZN.The ZooBank LSIDs (Life Science Identifiers) can be resolved and the associated information viewed through any standard web browser by appending the LSID to the prefix 'http:// zooba nk.org/' .The LSID for this publication is: urn:lsid:zoobank.org:pub:851A23EE-5D98-4556-AD8F-E01288A95F3F.

Horizon and locality
The age range of Baltic amber is still debatable, but the most current state of knowledge is that it is of Priabonian age, between 38 and 34 million years (based on pollen, spores and phytoplankton of the amber embedding layer, the so-called Blue Earth) 31 .
Thorax: wing (Figs. 1, 2, 3, 4) 2.43 mm long, 0.71 mm wide (holotype), 2.84 mm long, 0.68 mm wide (paratype), length of wing approximately 3× of its width; tip of Sc approximately in half the length of wing, before crossvein r-m; vein Mb longer than M 3 ; distal part of Cu from the point of connection of Cu with crossvein m-cu to the edge of wing almost straight; tip of A 2 distincly before half the length if wing, in 0.3× the length of Rs from fork of Rb.Haltere 0.35 mm long (holotype), 0.36 mm long (paratype).

Diagnosis
Wing with distinct wide trail along costal vein (C); tip of Sc before fork of Rs, in approximately 0.2× the length of Rs from its fork, sc-r in two of its length from edge of wing; Rs arrange more than half of Sc; r-r (R 2 ) situated at fork of Rs; basal section of R 5 (from fork of R 4+5 to connection of r-m) shorter than r-m; tip of R 1 reaching the edge of wing before tip of M 4 ; crossvein m-cu before fork of Mb, at a distance shorter than its length, beyond tip of A 2 .

Remarks
Due to the morphology of the wing venation, it became possible to identify a new species based on the characteristics of the female.The newly designated species differs significantly in wing venation from the already known species Tasiocera (Dasymolophilus) circumcincta Meunier 14 and also newly described herein species T. (D.) gorskii sp.nov.Alexander 32 gives the characteristics of the venation of both males and females, so it was possible to compare the venation of the wings, taking into account sexual dimorphism in some species of Diptera.

Etymology
The specific name 'baltica' is derived from Baltic amber.

Material examined
Holotype: No. MP/3106 (female), haused in the Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Kraków (ISEA PAS).

Horizon and locality
The age range of Baltic amber is still debatable, but the most current state of knowledge is that it is of Priabonian age, between 38 and 34 million years (based on pollen, spores and phytoplankton of the amber embedding layer, the so-called Blue Earth) 31 .Thorax: wing (Figs.5, 6) 2.70 mm long, 0.82 mm wide, length of wing 3.5× of its width; crossvein (h) situated in 0.16× the length of wing; crossvein sc-r situated in 2× of its length from the tip of Sc; tip of Sc before half the length of wing, before crossvein r-m and before fork of Rs; fork of Rb approximately in 0.3× the length of Mb; vein Mb approximately as long as M 3 ; distal part of Cu from the point of connection of Cu with crossvein m-cu to the edge of wing curved; tip of A 2 distincly before half the length if wing, in 0.3× the length of Rs from fork of Rb.Haltere 0.43 mm long.

Diagnostic characters
Wing without coloration; tip of Sc beyond fork of Rs, in approximately 0.14× the length of R 1 ; Rs not longer than half of Sc; r-r (R 2 ) situated at fork of Rs; basal section of R 5 (from fork of R 4+5 to connection of r-m) equal in length to r-m; tip of R 1 reaching the edge of wing beyond tip of M 4 ; crossvein m-cu at fork or just before fork of Mb, before tip of A 2 .

Material examined
No. MP/3085 (male), deposited in the Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Kraków (ISEA PAS).

Horizon and locality
The age range of Baltic amber is still debatable, but the most current state of knowledge is that it is of Priabonian age, between 38 and 34 million years (based on pollen, spores and phytoplankton of the amber embedding layer, the so-called Blue Earth) 31 .scape, tapered at base, slightly wider distally; not numerous, scape with slightly elongate setae, but shorter than segment bearing them, pedicel with a few elongate setae, two of them much longer than segment bearing them; on all flagellomeres a few very elongate seta, much longer than the length of segments bearing them.Palpus (Figs. 7,  8) 0.24 mm long; palpomeres 1-2 narow, slightly elongate, third palpomeres shorter than the last one, widened in midlength, last palpomeres slightly elongate, 4× as long as wide.On palpomeres a few slightly elongate setae, shorter than segments bearing them.

Discussion
The fossil record often provides detailed information about the morphology of extinct organisms, the history of their differentiation and shows direct evidence of evolutionary changes in many groups, also about the environment in the past epochs of Earth's history 16 .The most numerous group of animals in fossil resins of various ages are insects, among them representatives of Diptera.The fossil record proves that they were numerous starting from the Triassic 23,33 .Many extinct Limoniidae are known from the fossil record, and in the modern fauna there are such taxa of craneflies that the oldest representatives appeared not so early, for example, in the Eocene, like Elephantomyia Osten Sacken 34 , but also those known since the older periods like Cretaceous Helius 35 .Some genera of Limoniidae are very rare in the fossil record.The genus Tasiocera is represented in the modern fauna by over 70 species, but only one species has been known from the fossil record so far.The more valuable are the discoveries of new species for science, which is not without significance, for example, when reconstructing the evolutionary paths of the group of insects they represent, but also drawing conclusions about the environment in which these insects lived, including climatic conditions.In the Eocene, the northern part of today's Europe, about 40 Ma, was covered with mixed forests.In addition to trees of the genus Pinus, which probably produced large amounts of resin and were characteristic of a temperate or rather cold climate, there were sequoias and flowering plants typical of a hot climate.There are many examples confirming that in the Middle Eocene, about 30-40 Ma (this is more or less, how the age of Baltic amber is defined) insects preferring tropical and subtropical climates existed in the north of Europe 16 .
Tasiocera crane flies are present on all continents except Antarctica, but they are most numerous in Australia and Oceania and in the Ethiopian zoogeographical region (Table 1), which may explain their rare occurrence in Baltic amber.The oldest representatives of the genus Tasiocera are known from Baltic amber, so the beginning of the evolution of this group can be traced back to the Eocene period.In the Cretaceous some Limoniidae underwent rapid radiation with the adaptation to the new food spectrum.Flowering plants (Angiospermae) began to spread in this period, flies, belonging to the genus Helius, the oldest representatives of the subfamily Limoniinae (family Limoniidae, Nematocera), already at that time developed elongated mouthparts used to feed most likely on the nectar of flowers.The oldest species of the genus Helius are known from the Early Cretaceous Lebanese amber, such as Helius ewa Krzemiński, Kania & Azar 36 with a characteristic elongated rostrum 36 .
However, within the Limoniidae there are also known taxa that appeared much later, in the Eocene, as Tasiocera represented in fossil record only by the subgenus Dasymolophilus.
In the modern fauna out of the two subgenera distinguished within the genus Tasiocera-Tasiocera and Dasymolophilus much more biogeographically distributed is the subgenus Dasymolophilus.Slightly more diverse in terms of numer of species, but occurring in a relatively much smaller area (Australia and Oceania), is the subgenus Tasiocera, unrepresented in the fossil record.So far, there are no fossil records of flies of the genus Tasiocera, subgenus Tasiocera.The occurence of representatives of the Tasiocera subgenus only in Australia and Oceania may probably be due to the long geological isolation of the Austalian continent.Australia as a continent was part of Gondwana during the Jurassic period.The separation of India, Africa and Madagascar from this supercontinent meant that at one point it was only Antarctica, Australia and South America.The separation of Australia from the other two continents occurred about 96 Ma.As long as Australia was connected to or near Antarctica, warm air masses from Australia moved towards the South Pole.The Australian climate at that time was warm and humid.However, the northward drift of Australia around 46 Ma (thus increasing the distance between Australia and Antarctica) made the climate much drier.This proces was most intensified when Australia moved into tropical zone.Since the separation of Australia from Antarctica, its geological isolation began resulting in the emergence of a characteristic fauna on the Australian continent with a significant proportion of endemics 37 .
One previously known species T. (D.) circumcincta and two other described herein representing the genus Tasiocera were described on the basis of inclusions in Eocene Baltic amber, but the demonstration of the presence of antoher species of the subgenus Dasymolophilus in the former tropical Eocene forests of Europe shows that an even greater species diversity of this subgenus was possible in ancient epochs of Earth's history.The reasons for the absence of representatives of the Tasiocera subgenus in Baltic amber are probably to be sought in the presence of a significant geographical barier in the past.
Finding a new species is very significant, it allows for a better understanding of the group, evolutionary paths or phylogenetic relationships.Although one of the newly described species determined on the basis of the female morphological features, such as different wing venation or the presence of dark brown pattern of wing, leave no doubt that it is a representative of a different species than known from the fossil record so far.
Amber gives us the opportunity to see organisms that lived in the past.The bodies of insects preserved as an inclusions in different age of amber are three-dimensional preparations created by nature itself.Even if the original colors have not been preserved in amber, it is possible to determine the origin of color spots, for example on wings, and distinguish them from artifacts that sometimes occur in amber.An understanding of the taphonomic factors that control the preservation of color is key to assessing the fidelity with which original colors are preserved and can constrain interpretations of the visual appearance of fossil insects.Experimental taphonomic studies inform on how color alters during diagenesis.Preservation of color is controlled by a suite of factors, the most important of which relate to the diagenetic history of the host sediment, also color preservation relating to cuticular pigments in insects 38 .
The color of the stripes on the wings of T. (D.) baltica sp.nov.probably changed durring the fossilization process, but the shape of the colored area has been preserved.It is not artifact, even if the wings are not colored in modern members of the genus Tasiocera.The species T. (D.) baltica sp.nov. is easily distinguishable from other members of the subgenus discovered so far in the fossil record based on wing venation.Wing venation in T. (D.) circumcincta and T. (D.) gorskii differ significantly and these differences cannot be the result of sexual dimorphism.The most significant are the differences in length of veins Sc, Rs, position of veins sc-r, r-r (R 2 ) or the length of the basal section of R 5 .For example the tip of Sc T. (D.) gorskii sp.nov. is short, positioned before fork of Rs while in T. (D.) circumcincta tip of Sc is positioned beyond fork of Rs, crossvein sc-r in T. (D.) gorskii sp.nov. is situated one of its length from edge of wing, in T. (D.) baltica sp.nov.this vein occur in two of its length from edge of wing.In T. (D.) gorskii sp.nov.and T. (D.) baltica sp.nov.Rs arrange more than half of Sc, while in T. (D.) circumcintca Rs is rather short, not longer than half of Sc.The r-r (R 2 ) position is also noteworthy, in T. (D.) gorskii sp.nov.r-r (R 2 ) is situated beyond fork of Rs while in T. (D.) baltica sp.nov.and T. (D.) circumcincta r-r (R 2 ) is situated at the same level as fork of Rs (please, see the comparison section).Even if the structures of the hypopygium of T. (D.) circumcincta and T. (D.) gorskii sp.nov.are similar, the differences in the wing venation definitively indicate that they are different species and can be differentiated and on this basis they can also be distinguished from future new fossil Dasymolophilus findings.Although, a characteristic feature of the hypopygium of T. (D.) gorskii sp.nov. is that the gonostylus at midlength is expanded, very elongate, while in T. (D.) circumcincta the gonostylus in midlength is not so widened.

(Figs. 1 , 2 , 3 , 4 )
LSID urn:lsid:zoobank.org:act:6CCDB888-3437-477E-84A8-39631F538107.DiagnosisWing without spots; tip of Sc just before fork of Rs; sc-r in one of its length from edge of wing; Rs arrange more than half of Sc; r-r (R 2 ) situated beyond fork of Rs; basal section of R 5 (from fork of R 4+5 to connection of r-m) shorter than r-m; R 1 reaching the edge of wing before tip of M 4 ; crossvein m-cu situated before fork of Mb, at a distance equal to its length, beyond tip of A 2 .
7, 8) 2.65 mm long, 0.85 mm wide, the length of the wing corresponds to 3.5× its width, crossvein (h) situated at a distance corresponding to approximately 1/5 of the length of the wing, measured from its base; tip of vein Sc beyond half the length of wing, opposite crossvein r-m, beyond fork of Rs; fork of Rb approximately in half length of Mb; Mb longer than M 3 ; distal part of Cu from the point of connection of Cu with crossvein m-cu to the edge of wing almost straight; tip of A 2 in approximately in half the length of wing, just beyond half the length of Rs.Haltere short, the length of haltere 0.51 mm.Abdomen: hypopygium (Figs. 7, 8) 0.38 mm long, gonocoxite narrow, elongate, 0.19 mm long, gonostylus 0.09 mm long, narrow, elongate, tipped.Key to species of Dasymolophilus known from fossil record in respect to subgenera1.No macrotrichia on the wing membrana TasioceraThe presence of macrotrichia on the wing membrana … Dasymolophilus (2) 2. Tip of Sc before fork of Rs; Rs arrange more than half of Sc; basal section of R 5 (from fork of R 4+5 to connection of r-m) shorter than r-m; R 1 reaching the edge of before tip of M 4 ; crossvein m-cu far before fork of Mb … (3) Tip of Sc beyond fork of Rs; Rs shorter than half the lenght of the vein Sc; basal section of R 5 (from fork of R 4+5 to connection of r-m) equal to r-m; R 1 reaching the edge of beyond tip of M 4 ; crossvein m-cu at or just before fork of Mb … T.(D.) circumcincta (Figs.7, 8).

Table 2 .
List of the fossil specimens of the genus Tasiocera studied so far.