Glossodrilus

An unidentified species of Glossodrilus, copyright Thibaud Decaens.

Belongs within: Glossoscolecidae.

A place for worms
Published 18 December 2016

When we think of endangered species, we tend to focus on the charismatic vertebrates, such as pandas, parrots, tigers or turtles. But endangered species may come from all walks, crawls or wriggles of life. Have you ever considered, for instance, the plight of endangered earthworms?

Glossodrilus is a genus of earthworms found in tropical and subtropical regions of Central and South America. They are mostly fairly small as earthworms go, averaging only a few centimetres long and one or two millimetres in diameter. The largest, G. oliveirai from Brazil’s Roraima State and Guyana, is about 25 centimetres long; the smallest, G. tico from Roraima and Venezuela, is less than two centimetres in length. Most species lack pigmentation, meaning that they appear greyish from the colour of their gut contents. A single species, G. freitasi from Amapá State in Brazil, is a bright violet in colour. Other diagnostic features of the genus include: eight setae per segment, arranged in regular series; a pair of (or sometimes one) calciferous glands sitting above the oesophagus in segments XI to XII; two or three pairs of lateral hearts in segments VII to IX, and two pairs of intestinal hearts in X and XI; and a pair of testes in segment XI. Glossodrilus is distinguished from a closely related earthworm genus, Glossoscolex, by the absent of a pair of muscular copulatory chambers associated with the male ducts in the latter genus (Righi 1996).

Over sixty species have been assigned to Glossodrilus; as is usual with earthworms, they are mostly distinguished by internal characters such as features of the reproductive systems. They are most diverse in upland regions, with many species inhabiting high rain forest. A few species in the northernmost or southernmost parts of the genus’ range inhabit secondary grasslands. Glossodrilus species are conspicuous by their absence in the Brazilian central plateau, and only infrequently present in lowland Amazonia (Righi 1996).

And this is where the question of conservation comes in. You see, the greater number of Glossodrilus species are known only from a very restricted area (Lavelle & Lapied 2003). Part of this may be an artefact of sampling: in more recent decades, our understanding of South American earthworm diversity has been heavily shaped by one researcher, Gilberto Righi of the Universidade de São Paulo, and we know little of areas where Righi did not collect specimens himself or from where he did not receive specimens supplied by ecological surveys. Nevertheless, sampling has probably been extensive enough to expect that the low number of shared species between different regions will hold firm at the broad scale at least. Most Glossodrilus species (and other native South American earthworms) are dependent on old-growth habitats; as land is cleared for farming, forestry and the like, exotic and invasive earthworm species take over. It would be all to easily for the little Glossodrilus to find themselves homeless, and slip into extinction without any to mark their passing.

Systematics of Glossodrilus
<==Glossodrilus Cognetti 1905 [incl. Andioscolex Michaelsen 1927, Tonperoge Righi & Ayres 1975]R96
    |--*G. parvus Cognetti 1905R96 [=Andioscolex parvusR71]
    |--G. aioca Righi 1975R96
    |--G. antisanae Zicsi 1989R96
    |--G. antunesi (Righi 1971)R96 [=Andioscolex antunesiR72; incl. G. baiuca Hamoui & Donatelli 1983R96]
    |--G. arapaco Righi 1982R96
    |--G. baloghi Zicsi 1988R96
    |--G. benavidesi Zicsi 1989R96
    |--G. bresslaui (Michaelsen 1918)R96 [=Andioscolex bresslauiR71]
    |--G. chami Righi 1996R96
    |--G. chimborazoi Zicsi 1989R96
    |--G. cibca Righi & Fraile-Merino 1987R96
    |--G. cigges (Righi 1970)R96
    |--G. crassicauda (Cognetti 1905)R96 [=Andioscolex crassicaudataR71]
    |--G. crucifer Righi & Römbke 1987R96
    |--G. dithecae Righi 1988 [=G. uete dithecae]R96
    |--G. dorasque Righi & Fraile-Merino 1987R96
    |--G. excelsus (Cognetti 1904)R96 [=Andioscolex excelsusR71]
    |--G. fontebonensis Righi 1988R96
    |--G. fragilis Zicsi 1989R96
    |--G. freitasi (Righi 1971)R96 [=Andioscolex freitasiR71]
    |--G. geayi (Cernosvitov 1934)R96 [=Andioscolex geayiR71]
    |--G. hondaensis (Michaelsen 1900)R96 [=Andioscolex hondaensisR71]
    |--G. itajo (Righi 1971)R96 [=Andioscolex itajoR71]
    |--G. kaszabi Zicsi 1988R96
    |--G. kuna Righi 1996R96
    |--G. landeszi Zicsi 1988R96
    |--G. loksai Zicsi 1989R96
    |--G. mahnerti Zicsi 1989R96
    |--G. mairaro Righi 1982R96
    |--G. marabora Righi 1984R96
    |--G. marcusae (Righi 1969)R96 [=Andioscolex marcusaeR71]
    |--G. meridionalis (Cognetti 1904)R96 [=Andioscolex perrieri meridionalisR71, G. perrieri meridionalisR96]
    |--G. motu Righi 1990R96
    |--G. mucupois (Righi 1970)R96 [=Andioscolex mucupoisR72]
    |--G. nemoralis (Cognetti 1905)R96 [=Andioscolex nemoralisR71]
    |--G. oliveirae Righi 1982R96
    |--G. orosi Righi & Fraile-Merino 1987R96
    |--G. ortonae Righi 1988R96
    |--G. paez Righi 1996R96
    |--G. palenke Righi 1996R96
    |--G. pan Righi 1984R96
    |--G. panikita Righi 1996R96
    |--G. paolettii Righi 1984R84
    |--G. papillatus Zicsi 1989R96
    |--G. parecis Righi & Ayres 1975 [=G. (Tonperog) parecis; incl. Glossoscolex minutus Ljungström et al. 1975 (n. n.)]MR99
    |--G. peregrinus (Michaelsen 1897)R96 [=Tykonus peregrinusR71, *Andioscolex peregrinusR71]
    |--G. perrieri (Cognetti 1904) [=Andioscolex perrieri]R96
    |--G. pixao Righi & Garcia 1989R96
    |--G. saija Righi 1996R96
    |--G. schubarti Righi, Ayres & Bittencourt 1978R96
    |--G. schuetti (Michaelsen 1918)R96 [=Andioscolex schuttiR71]
    |--G. seidlae Zicsi 1989R96
    |--G. smithi (Cognetti 1905)R96 [=Andioscolex smithiR71]
    |--G. sucunduris Righi, Ayres & Bittencourt 1976R96
    |--G. teranae Zicsi 1989R96
    |--G. tico Righi 1982R96
    |--G. tinga (Righi 1971)R96 [=Andioscolex tingaR71]
    |--G. tocantinensis (Righi 1972)R96 [=Andioscolex tocantinensisR72]
    |    |--G. t. tocantinensisR96
    |    `--G. t. pola Righi 1984R96
    |--G. totaritoensis Righi 1996R96
    |--G. tuberculatus Zicsi 1989R96
    |--G. uete Righi 1988R96
    |--G. unguis Righi 1996R96
    |--G. venancioi Righi 1982R96 [=G. (Tonperog) venancioiR82]
    `--G. yuko Righi 1996R96

*Type species of generic name indicated

References

Lavelle, P., & E. Lapied. 2003. Endangered earthworms of Amazonia: an homage to Gilberto Righi. Pedobiologia 47: 419–427.

[MR99] Mischis, C. C. de, & G. Righi. 1999. Contribution to knowledge of the oligochaete fauna (Annelida, Oligochaeta) from Argentina. Gayana 63 (2): 63–65.

[R71] Righi, G. 1971. Sôbre a família Glossoscolecidae (Oligochaeta) no Brasil. Arquivos de Zoologia 20 (1): 1–95.

[R72] Righi, G. 1972. Contribuição ao conhecimento dos Oligochaeta brasileiros. Papéis Avulsos de Zoologia 25 (18): 149–166.

[R82] Righi, G. 1982. Oligochaeta, Glossoscolecidae, do Parque Nacional da Amazônia, Tapajós. Revista Brasileira de Biologia 42 (1): 107–116.

[R84] Righi, G. 1984. Nova contribuição ao conhecimento dos Oligochaeta da Venezuela. Papéis Avulsos de Zoologia 35 (22): 243–256.

[R96] Righi, G. 1996. Colombian earthworms. Studies on Tropical Andean Ecosystems 4: 485–607.

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