Lumbricidae Rafinesque-Schmaltz, 1815

Misirlioğlu, Mete, Reynolds, John Warren, Stojanović, Mirjana, Trakić, Tanja, Sekulić, Jovana, James, Samuel W., Csuzdi, Csaba, Decaëns, Thibaud, Lapied, Emmanuel, Phillips, Helen R. P., Cameron, Erin K. & Brown, George G., 2023, Earthworms (Clitellata, Megadrili) of the world: an updated checklist of valid species and families, with notes on their distribution, Zootaxa 5255 (1), pp. 417-438 : 425

Lumbricidae Rafinesque-Schmaltz, 1815

The Lumbricidae is the phylogenetically youngest family in the subclass of Oligochaeta. The family perhaps originated in the Palearctic but there is a well-supported clade native to Eastern North America. Overall, the Lumbricidae family comprises some 615 species and 74 subspecies belonging to 47 genera ( Brown et al. 2023), although the lumbricid taxonomy is still controversial and not yet settled ( Bouché 1972; Mršić 1991; Qiu & Bouché 1998; Csuzdi & Zicsi 2003; Domínguez et al. 2015; de Sosa et al. 2019; Marchán et al. 2022a; Marchán et al. 2022c). Around 33 cosmopolitan species of the family are widespread and often invasive in numerous regions ( Blakemore 2009), such as North America, Australia, New Zealand, South Africa, Southern South America, and even in equatorial countries at higher elevation (e.g., Zicsi 2007).

In North America there are both native and non-native species and genera. The native genera are Bimastos and Eisenoides with 15 and two species, respectively. There are 11 genera of non-native invasive lumbricids in North America ( Fragoso & Rojas 2014; Reynolds 2020, 2022), and 10 genera of invasives in South America ( Fragoso & Brown 2007). In Europe, centers of diversity of lumbricids are situated in the Pyrenees and the Balkan Peninsula, as well as in the Carpathians and the Caucasus ( Kvavadze 1985, 1999; Rota & de Jong 2015). The biodiversity of the Balkans is the largest in Europe ( Griffiths et al. 2004), due to the complex geological history and the specific geographical position with several biogeographical regions, each characterized by specific ecological, climatic and geomorphological conditions, as well as a great variety of habitats ( Trakić et al. 2016).

For the last 2 million years, repeated glaciations have destroyed the biotas of much of northern and alpine Europe, and on the major mountain ranges such as the Carpathians, Caucasus, and Pyrenees. The present European earthworm fauna consists of the survivors in unglaciated, non-permafrosted areas, and their descendants who colonized the rest of the continent after the end of the last (W̧rm or Wisconsinan) glaciation. There is no way to know how many species were driven to local or global extinction. Repeated cycles could have contributed to inrefuge speciation by changing vegetation zonation. However, the pre-Pleistocene conditions were probably adequate to support earthworm populations throughout Europe and even into the Arctic, including the North American Arctic, as subtropical vegetation fossils from the Eocene occur on Ellesmere Island ( Eberle & Greenwood 2012; Francis 1991).

Today, most earthworm scientists agree that the original lumbricid fauna was significantly destroyed during the glacial period in much of Europe. Today's lumbricid fauna come from various elements, differing both in their historical age and in their origins. Namely, the present faunal elements are fragments of modified fauna from the Tertiary Period, that are thought to have originated in the Paleocene or Eocene. These are species that, due to their adaptability to specific conditions, have survived to this day. Such relic species are now present in the Balkans, the Pyrenees and the Apennine peninsula, the northwestern part of Africa (Maghreb), the southern part of France, Sardinia, Corsica, the southern parts of Switzerland and the Czech Republic, Turkey and the central parts of Asia ( Omodeo 1952, 1956, 1961, 1988; Bouché 1972, 1983; Mısırlıoğlu 2017; Mršić & Šapkarev 1988; Mršić 1991; Marchán et al. 2020; Marchán et al. 2022b). In addition to relic species, there are also "modern" species that are thought to have appeared in the Miocene and later. A greater expansion of new "modern" species occurred during interglacial and postglacial periods, mainly in the Holocene ( Mršić 1991).

On the Balkan Peninsula there are 90 endemic species with the largest share in Dendrobaena (25) and Allolobophora (20) ( Trakić et al. 2016; Popovic et al. 2022), while 39 have been discovered in the basin of the Carpathians, mostly Dacian endemics. Of these, 12 species are of the genus Octodrilus whose distribution center is located in the Apuseni Mountains in the southern part of the Carpathians ( Csuzdi et al. 2011). Other genera appear to be endemic from southern France to the northern Iberian Peninsula. The most speciose is presently Scherotheca with 42 species/subspecies recognized to date, though many other species are still expected to be found (e.g., eight new species were recently described from Corsica; Marchán et al. 2023a).

The ecologically important Lumbricidae have been explored using various tools by numerous researchers. Despite significant molecular research, there are still many species that do not have a stable taxonomic status, most of which relate to archaic species with unique taxonomic characteristics and disjunctive distributions ( Marchán et al. 2022c). Answers to some of these questions are expected in the near future, and will certainly lead to a better understanding of many concerns regarding the origin and dynamics of the development of the Lumbricidae family as a whole.