Obama (flatworm) explained

Obama is a genus of land planarians from South America. It contains several species adapted to human-disturbed environments,[1] including the only invasive land planarian native to the Neotropical realm, Obama nungara, which has been accidentally introduced in Europe.[2]

Description

The genus Obama is characterized by having a leaf-shaped body. Most species are about 10cm (00inches) long, but some may reach over 20cm (10inches). The hundreds of eyes distributed along the body are of two types: monolobulated, which are simple and circular, and trilobulated, which have three lobes.[3]

The copulatory apparatus of Obama has a protrusible penis occupying the entire male atrium or most of it.[4] Morphologically the genus can be divided in two subgroups depending on the shape of the penis papilla, which may be symmetrical or asymmetrical. The group with an asymmetrical penis papilla includes 10 species (O. anthropophilla, O. carbayoi, O. carrierei, O. decidualis, O. josefi, O. ladislavii, O. marmorata, O. nungara, O. otavioi and O. ruiva) and seems to form a monophyletic clade within Obama.[5] On the other hand, the group with a symmetrical penis papilla is paraphyletic, indicating that this is the ancestral state within the genus.

Etymology

The name Obama is formed by a composition of the Tupi words oba (leaf) and ma (animal), being a reference to the body shape of species in this genus. It is not named after Barack Obama and the similarity between the names is pure coincidence.

Species

There are 45 species assigned to the genus Obama, making it the largest genus in the subfamily Geoplaninae:

Phylogeny

The genus Obama was erected after a study of molecular phylogeny with the subfamily Geoplaninae revealed that the genus Geoplana, originally containing more than a hundred species, was polyphyletic. One of the monophyletic clades revealed by the study was separate from Geoplana as the new genus Obama. All species within the new genus share a similar morphology, including the leaf-shaped body, the presence of a permanent penis papilla, ovovitelline ducts entering the female atrium dorsally and dorsal eyes of two types: mono- and trilobulated.

The sister-group of Obama seems to be the genus Cratera, which has a very similar appearance but lacks trilobulated eyes.[8]

The following phylogenetic tree shows the relationship of several species of Obama after several molecular studies:

Notes and References

  1. Boll . Piter Kehoma . Leal-Zanchet. Ana Maria. Preference for different prey allows the coexistence of several land planarians in areas of the Atlantic Forest . Zoology . 2016 . 0944-2006 . 10.1016/j.zool.2016.04.002 . 119 . 3 . 162–168. 27156235 .
  2. Carbayo . Fernando . Álvarez-Presas . Marta . Jones . Hugh D. . Riutort . Marta . The true identity of Obama (Platyhelminthes: Geoplanidae) flatworm spreading across Europe. Zoological Journal of the Linnean Society . 177 . 1 . 2016 . 5–28 . 0024-4082 . 10.1111/zoj.12358. free .
  3. 10.1111/zsc.12019. Molecular phylogeny of Geoplaninae (Platyhelminthes) challenges current classification: Proposal of taxonomic actions. Zoologica Scripta. 42. 5. 508–528. 2013. Carbayo . F. . Álvarez-Presas . M. . Olivares . C. U. T. . Marques . F. P. L. . Froehlich . E. X. M. . Riutort . M. .
  4. Marques . Alessandro . Rossi . Ilana . Valiati . Victor Hugo . Leal-Zanchet . Ana Maria . Integrative approach reveals two new species of Obama (Platyhelminthes: Tricladida) from the South-Brazilian Atlantic Forest . Zootaxa . 4455 . 1 . 2018 . 99–126 . 1175-5334 . 10.11646/zootaxa.4455.1.4. 30314222 .
  5. Carbayo . Fernando . Francoy . Tiago M.. Giribet . Gonzalo . Non-destructive imaging to describe a new species of Obama land planarian (Platyhelminthes, Tricladida) . Zoologica Scripta . 2016 . 45 . 5 . 566–578 . 0300-3256 . 10.1111/zsc.12175.
  6. Iturralde . Giuly G. . Allgayer . Heloísa . Valiati . Victor H. . Leal-Zanchet . Ana M. . Seeing the true colours: three new species of Obama (Platyhelminthes : Continenticola) from remnants of Atlantic forest in southern Brazil based on an integrative approach . Invertebrate Systematics . 34 . 2021 . 312–331 . 10.1071/IS20043.
  7. Negrete . Lisandro . Gira . Rafael Díaz . Brusa . Francisco . Two new species of land planarians (Platyhelminthes, Tricladida, Geoplanidae) from protected areas in the southern extreme of the Paranaense Rainforest, Argentina . Zoologischer Anzeiger . 279 . 2019 . 38–51 . 00445231 . 10.1016/j.jcz.2019.01.002.
  8. Rossi . Ilana . Amaral . Silvana Vargas . Ribeiro . Giovana Gamino . Cauduro . Guilherme Pinto . Fick . Israel . Valiati . Victor Hugo . Leal-Zanchet . Ana Maria . Two new Geoplaninae species (Platyhelminthes: Continenticola) from Southern Brazil based on an integrative taxonomic approach . Journal of Natural History . 50 . 13–14 . 2015 . 787–815 . 0022-2933 . 10.1080/00222933.2015.1084057. 86172935 .

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