The Limoniidae are a large group of small-to-medium sized Crane Flies, Tipuloidea, with coloured or patterned wings, which are sometimes shortened or otherwise reduced. There are over 11 000 extant species within the family Limoniidae, divided into four subfamilies, the Chioneinae, Dactylolabinae, Limnophilinae and Limoniinae, with phylogenetic analyses suggesting that the Dactylolabinae are likely to be the oldest group. All members of the subfamily Dactylolabinae are currently placed within a single genus, Dactylolabis, with living members divided into four subgenera, Bothrophorus, Coenolabis, Dactylolabis and Eudactylolabis. Of these subgenera only Dactylolabis has a fossil record, being known from Eocene Baltic Amber, with four extinct subgenera, Aurolabis, Eobothrophorus, Eolabis and Idiolabis also used to describe Baltic Amber species.
In a paper published in the journal Palaeontologica Electronica in January 2015, Iwona Kania of the Department of Environmental Biology at Rzeszów University and Wiesław Krzemiński of the Institute of Systematic and Evolution of Animals at the Polish Academy of Sciences describe a new species of Dactylolabis from Eocene Baltic Amber.
The new species is placed in the subgenus Idiolabis and given the specific name ryszardi, in honour of Ryszard Szadziewski, an expert on fossil and living flies. Dactylolabis (Idiolabis) ryszardi i described from a single male specimen 7.3 mm in length, with 9.76 mm wings.
Dactylolabis (Idiolabis) ryszardi, male specimen in lateral view. Kania & Krzemiński (2015).
The long-lived status of the subgenus Dactylolabis (Dactylolabis), with all other described subgenera being either modern or Eocene, has recently been questioned. A phylogenetic analysis carried out by Kania and Krzemiński suggests that all the described subgenera are indeed discreet evolutionary lineages (although some of the Eocene subgenera contain only a single species), though the Eocene and modern members of Dactylolabis (Dactylolabis) are not particularly closely related.
Kania and Krzemiński observe that while the Eocene forests of Fennoscandia, which produced the Baltic Amber, were a warm-forest environment with little seasonal variation, similar to forests found closer to the equator today, these forests covered a vast geographical range, extending a long way north-to-south and also containing a wide range of altitudinal variation. This suggests that these forests would have had a high number of different environments within them, as is the case with modern tropical forests, but that this ecological variation is hidden somewhat by the nature of the Baltic Amber deposits, which contain river-transported material carried from many different areas by the action of vast ancient waterways.
Modern members of the subgenus Dactylolabis (Dactylolabis) are widely distributed, and have are tolerant of a broad range of environments, while the other modern subgenera of Dactylolabis are much more limited, with more specialized environmental requirements. Kania and Krzemiński suggest that the same may have been the case in the Eocene, with subsequent environmental change wiping out the more specialized groups while the more tolerant Dactylolabis (Dactylolabis) survived. This scenario makes it highly likely that Dactylolabis (Dactylolabis) is in fact polyphyletic as well as morphologically conservative, with more specialized forms repeatedly arising from within this subgenus
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