Benhamiidae Michaelsen, 1897

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 : 422

Benhamiidae Michaelsen, 1897

Native species of the Benhamiidae (351 species and 6 subspecies in 20 genera) are mainly restricted to subSaharan Africa, Oceania, Central America and northern South America (Csuzdi 2010). However, a few Dichogaster (including the type species of the genus) are also known from the Pacific islands of Fiji and Samoa ( Easton 1984; James & Davidson 2012). In Africa, the native Benhamiidae are present mainly in the tropical region with 16 genera ( Afrogaster , Agastrodrilus , Benhamia , Benhamiona , Dichogaster , Dudichiodrilus , Guineoscolex , Loksaia , Millsonia , Monogaster , Monothecodrilus , Omodeona , Pickfordia , Pickfordiella , Reginaldia and Wegeneriella ) and ca. 250 species. From the Neotropics, i.e., the Caribbean islands, Central America, Mexico, and Northern South America we know five genera ( Dichogaster , Eutrigaster , Neogaster , Omodeoscolex , and Wegeneriona ) and around 100 species, mainly of Dichogaster and Eutrigaster , many of which show high endemism rates, particularly on the Caribbean islands. The diversity of the minute South-American species is certainly underestimated due to a lack of sampling, especially in Amazonia, where recent work (in French Guyana), revealed several new species, that are presently being described.

Several species in the family Benhamiidae , particularly in the genus Dichogaster , are widespread anthropochores in the tropics, as their native ranges were probably originally in Central and Eastern Africa ( Gates 1972; Csuzdi 2010). These species were probably widely dispersed during the centuries of commercial product exchanges between Africa and other continents, where ships could have transported soil in planted pots containing these generally parthenogenetic species. More recent transport with manure piles or agricultural equipment may also have led to the abundance of Dichogaster gracilis (Michaelsen) , Dichogaster bolaui (Michaelsen) , Dichogaster saliens (Beddard) , and Dichogaster affinis (Michaelsen) in many no-tillage sites in Southern and Central Brazil, where they may reach abundances well over 100 individuals m-2 ( Bartz et al. 2009; Bartz et al. 2014; Santos et al. 2018). Although Dichogaster spp. are generally restricted to warm and humid tropical regions, several species have been reported from greenhouses in temperate climates and at least one species ( D. bolaui ) was considered a domicole (adapted to human homes) species, as it was found in bathtubs, showers and sewage pipes in Hungary, Ireland, Finland, Sweden and Israel ( Terhivuo 1991; Erséus et al. 1994; Rota & Schmidt 2006; Csuzdi et al. 2008). In fact, the type locality of D. bolaui is Hamburg, where it was found in fermenting bark at a factory ( Michaelsen 1891). Dichogaster annae (Horst) is an epigeic species, common in vermicomposting ventures in tropical countries such as Brazil (James & Guimar„es 2010), but its distribution is probably much wider than presently known or reported, due to the lack of recognition by worm composters, and the little knowledge of its life-cycle and biology. Dichogaster modiglianii (Rosa) is an epi-endogeic species also with wide distribution (Africa, Southeast Asia, Australia, Oceania, Central America, Caribbean, Southern North America ( Blakemore 2010), and was recently found in several Amazonian sites, associated with Pre-Columbian human activities ( Conrado 2018). Specimens of D. bolaui were also recently reported from a remote and human-free Amazonian rainforest area in Southern French Guyana, highlighting the potential of these cosmopolitan species to establish stable populations that persist centuries after original introduction by humans ( Maggia et al. 2021).