Earthworms and Their Allies

by Frank E. Beddard

In South America we find that the bulk of the indigenous earthworms belong to the family Geoscolecidae and to a definite sub-family, viz. Geoscolecinae. These genera are Onychochaeta with one species, Hesperoscolex of which one species is known from the area, Periscolex with one species, Anteoides with two species, Pontoscolex one species. Opisthodrilus with two species, Rhinodrilus (including either as synonyms or as sub-genera, Thamnodrilus, Anteus, Tykonus, Urobenus and Aptodrilus) with no less than 49 species: Andiodrilus with five species, Holoscolex with one species, Glossoscolex ten species, Fimoscolex, Andiorrhinus and Enantiodrilus with one species apiece.

Thus of this sub-family of Geoscolecidae we have in South America a large number of genera and a much larger number of species. Of a second sub-family of Geoscolecidae there are three species of Criodrilus found in the South American Continent.

We now turn to the Megascolecidae of which a large number of species occur within the area now under consideration. The bulk of these belong to the sub-family Acanthodrilinae and they are as follows:

Of the genus Notiodrilus there are ten species, of Microscolex two species, of Chilota 19, of Yagansia 13.

A second sub-family Trigastrinae also occurs in this Continent and the following genera are permanent inhabitants, viz.:—

Dichogaster (= Benhamia) with only three species, of which two at least are found elsewhere, and of which therefore the autochthonism is doubtful.

Finally, there is the sub-family Ocnerodrilinae comprising the following genera: Kerria with ten species, Ocnerodrilus (with sub-genera Liodrilus, Ilyogenia and Haplodrilus) four species, which again are rather doubtful indigenes of the South American Continent.

Leaving aside certain species (of the genera Lumbricus, Pheretima, etc.) which are clearly not indigenous, the South American Continent harbours 150 kinds of earthworms which are distributed in some 19 genera. But of these a few species (e.g. Onychochaeta windlei, Kerria macdonaldi) stray into neighbouring regions, i.e. the West Indies and California. It is doubtful therefore whether they are to be referred to as limited to one of these regions and accidentally imported into the others, or whether they are genuine inhabitants of both.

The South American Continent shares with the West Indies the following genera, but the species (except in the case of Onychochaeta windlei, Glossoscolex peregrinus) are distinct; these genera are Hesperoscolex, Pontoscolex, Dichogaster, and Ocnerodrilus. Diachaeta is limited to the West Indies.

The following South American genera are also found in Central and warmer North America (Mexico, California), viz. Hesperoscolex, Periscolex, Rhinodrilus, Pontoscolex, Andiodrilus, Glossoscolex, Notiodrilus, Microscolex, Dichogaster, Kerria and Ocnerodrilus. But with the exception of Hesperoscolex, which seems to belong rather to Central America and the West Indies, Microscolex and Pontoscolex which are world-wide and whose original home is therefore difficult to fix, and Dichogaster and Ocnerodrilus which would seem rather to be rare immigrants (perhaps not truly indigenous) into South America, these genera are practically distinctively South American.