Corresponding author: Fernando Carbayo ( baz@usp.br ) Academic editor: Marcus V. Domingues
© 2018 Amanda Cseh, Fernando Carbayo, Eudóxia Maria Froehlich.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Cseh A, Carbayo F, Froehlich EМ (2017) Observations on food preference of Neotropical land planarians (Platyhelminthes), with emphasis on Obama anthropophila, and their phylogenetic diversification. Zoologia 34: 1-8. https://doi.org/10.3897/zoologia.34.e12622
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The food preference of Obama anthropophila Amaral, Leal-Zanchet & Carbayo, 2015, a species that seems to be spreading across Brazil’s human-modified environments, was investigated. Extensive experiments led to the conclusion that the generalized diet of this species may have facilitated its dispersal. The analysis of 132 feeding records of 44 geoplaninid species revealed a tendency for closely related species to feed on individuals from similar taxonomic groups, suggesting that in this group behavioral evolution is more conserved than phylogenetic diversification.
Diet, flatworm, Geoplaninae, predation, soil fauna.
Land planarians, or Geoplanidae (Platyhelminthes: Tricladida), are nocturnal predators that are common in humid forests (
The general knowledge about these organisms is still far from satisfactory, especially with regards to their biology (
Studies on the feeding preferences of land planarians have, for the most part, focused on species that are found out of their natural distribution range. They have received this kind of attention as a result of their potentially detrimental impact on native faunas. This is the case of the bipaliinids Bipalium kewense (Moseley, 1878), B. adventitium Hyman, 1943, the rhynchodeminids Platydemus manokwari Beauchamp, 1962, Arthurdendyus triangulatus (Dendy, 1894), Endeavouria septemlineata (Hyman, 1939) and the geoplaninid Obama nungara
Additional studies including data on the diet of native or exotic land planarians can be found in the literature. These data might provide insights on the food preferences of congeners, even though their diet has not been addressed yet.
In the present study, (a) further experiments were carried out to study the diet preferences of the northern population of O. anthropophila, and (b) data on their diet was compiled from field and laboratory observations, as well as from the literature, and mapped onto a genus-level classification of land planarians of the subfamily Geoplaninae, in order to evaluate the behavioral evolution of these animals during their phylogenetic diversification.
We focused on land planarians of the subfamily Geoplaninae. Data on their diet were obtained from three sources: (a) sets of trials and experiments under laboratory conditions using O. anthropophila, (b) our own occasional observations in nature and under laboratory conditions, and (c) published literature.
Nineteen specimens of O. anthropophila were collected during the day between May, 2011 and February, 2012, from the Parque Ecológico do Tietê, in the city of São Paulo, state of São Paulo, Brazil (23°29’06”S 46°31’12”W). The 1400 ha. park is a managed area comprised of meadows, patches of flowers and trees, mainly exotic species. At the time of capture, most individuals were photographed with a digital camera and the length of each specimen was measured. Each specimen was then placed in a labeled cylindrical plastic container with a cotton ball moistened with mineral water, and 2-3 pieces of tree bark for refuge. The containers measured either 10 x 5 cm (diameter x height) (those were allocated for specimens less than 2 cm long), or 11 × 7 cm (allocated for specimens larger than 2 cm). The containers were kept in a cardboard box to provide darkness, at room temperature and humidity, in the Laboratório de Ecologia e Evolução. The containers were cleaned twice a week, with the cotton balls substituted with fresh ones. Five different species of invertebrates that are abundant at the sampling site and coexist with O. anthropophila, were offered as potential prey. Some prey were known to be food items of O. anthropophila (land planarians and mollusks) (
In order to stimulate readiness to feed (
Additionally, 25 experiments involving O. anthropohila with ten different options of prey were carried out. In this case, flatworms that had survived previous trials were starved for 10 days before being offered prey, in accordance with the established procedure.
A summary was compiled with the available diet records and prevailing conditions of diet, both from our own field and lab notes taken since the 1950s (Tables
Specimens of O. anthropophila survived up to 150 days under laboratory conditions (median 20 days; range 6–150 days; Table
Data were obtained on the diets of 44 species of Geoplaninae. A total of 132 records (45 new, Tables
Nine species of Obama predate on gastropods, and six on other land flatworms. However, O. anthropophila preyed upon nine species across three phyla, including three introduced species, Deroceras laeve (Müller, 1774) from North America (
Matuxia tuxaua (E.M. Froehlich, 1955) and M. matuta (E.M. Froehlich, 1955) feed on beetle larvae, and four species of Luteostriata as well as I. rezendei feed exclusively on woodlice, rejecting any other kind of prey (
Two species of Cephaloflexa feed on harvestmen, while one of them, C. bergi, also takes other arthropods, such as Diptera and woodlice (Tables
Survival and predation rate (indicated as preyed/offered) of 19 specimens of Obama anthropophila when fed with one out of five different types of prey species under laboratory conditions. A specimen not given as prey is indicated with a hyphen. See Material and Methods for details.
Specimen identification | Specimen survival (days) | Issoca rezendei (Geoplaninae) | Luteostriata ernesti (Geoplaninae) | Geoplana quagga (Geoplaninae) | Deroceras laeve (Gastropoda) | Millipede (Diplopoda) | # trials |
---|---|---|---|---|---|---|---|
A | 150 | 3/6 | 1/2 | 2/6 | 2/6 | 0/5 | 25 |
C | 76 | 4/6 | 1/2 | 1/5 | 1/2 | 0/3 | 18 |
B | 50 | 2/3 | 0/1 | 1/2 | 2/3 | 0/2 | 11 |
D | 50 | 2/3 | 2/2 | 1/3 | 0/1 | 0/1 | 10 |
X | 89 | 1/2 | 0/1 | – | 1/1 | 0/1 | 5 |
J | 6 | 0/1 | 0/1 | 0/1 | 0/1 | 0/1 | 5 |
E | 20 | 0/1 | 0/1 | 0/1 | 0/1 | 0/1 | 5 |
Alpha | 70 | 0/1 | 2/2 | – | – | 0/1 | 4 |
P | 13 | 0/1 | – | 0/1 | 0/1 | 0/1 | 4 |
Z | 19 | 1/1 | 1/1 | – | 0/1 | – | 3 |
N | ? | 1/1 | – | 0/1 | – | – | 2 |
B2 | 20 | 1/1 | 0/1 | – | – | – | 2 |
B1 | 19 | 0/1 | – | 0/1 | – | – | 2 |
O | 6 | 1/1 | – | – | – | – | 1 |
L | 6 | – | – | – | 1/1 | – | 1 |
I | 6 | – | 1/1 | – | – | – | 1 |
H | ~20 | 1/1 | – | – | – | – | 1 |
G | 20 | – | – | 1/1 | – | – | 1 |
F | ~20 | – | – | – | 1/1 | – | 1 |
56.7% (17/30) | 53.3% (8/15) | 27.3% (6/22) | 42.1% (8/19) | 0.0% (0/16) | 102 |
Feeding preferences of species of Geoplaninae land planarians presented here for the first time. Observation conditions, either in nature (nat) or in the laboratory (lab), and references are given in brackets; a hyphen indicates observation conditions as unavailable.
Land flatworm species | Invertebrate consumed |
---|---|
Cephaloflexa bergi (Graff, 1899) | Harvestman Progonyleptoidellus striatus (Roewer, 1913) (Gonyleptidae, Opiliones) [lab] |
Harvestman Neosadocus sp. (Gonyleptidae, Opiliones) [nat] | |
Harvestman Mischonyx cuspidatus (Roewer, 1913) (Gonyleptidae, Opiliones) [lab] |
|
Unidentified insect larva [nat] | |
Unidentified harvestman (Fig. |
|
Cephaloflexa bergi (Graff, 1899) | Cricket Gryllus sp. (Orthoptera, Insecta) [lab] |
Unidentified woodlice (Oniscidea, Crustacea) [-] | |
Larva of Tenebrio sp. (Coleoptera) [lab] | |
Geobia subterranea Schultze & Müller, 1857 | Unidentified earthworm (Oligochaeta, Annelida) [nat] (Fig. |
Geoplana beckeri Froehlich, 1959, incertae sedis | Unidentified earthworm (Oligochaeta, Annelida) [-] |
Geoplana cf. chita Froehlich, 1956 | Unidentified land snail (Gastropoda) [nat] (Fig. |
Geoplana goetschi Riester, 1938 incertae sedis | Unidentified land leech (Hirudinea, Annelida) [nat] |
Geoplana quagga Marcus, 1951, incertae sedis | Torn land slug Limax sp. (Gastropoda) [lab] |
Land planarian Dolichoplana striata Moseley, 1877 (Geoplanidae) [lab] | |
Unidentified woodlice (Oniscidea, Crustacea) [lab] | |
Imbira marcusi |
Unidentified earthworm (Oligochaeta) [nat] (Fig. |
Issoca rezendei (Schirch, 1929) | Unidentified woodlice (Oniscidea, Isopoda) [lab] |
Luteostriata caissara (E. M. Froehlich, 1955) | Unidentified woodlice (Oniscidea, Isopoda) [lab] |
Luteostriata ernesti (Leal-Zanchet & E. M. Froehlich, 2006) | Unidentified woodlice (Oniscidea, Isopoda) [lab] |
Luteostriata sp. | Unidentified woodlice (Oniscidea, Isopoda) [lab] |
Notogynaphallia plumbea (Froehlich, 1959) | Unidentified larva of an insect [nat] |
Notogynaphallia sexstriata (Graff, 1899) |
Insecta: larva of an insect [nat] (Fig. |
Obama anthropophila Amaral, Leal-Zanchet & Carbayo, 2015 | Land planarian Issoca rezendei (Schirch, 1929) (Geoplanidae) [lab] (Fig. |
Land planarian Luteostriata ernesti (Leal-Zanchet & Froehlich, 2006) (Geoplanidae) [lab] (Suppl. material |
|
Land planarian Geoplana quagga Marcus, 1951, (Geoplanidae) [lab] | |
Land planarian Geobia subterranea Schultze & Müller, 1857 (Geoplanidae) [lab] (1/2) | |
Land planarian Endeavouria septemlineata (Hyman, 1939) (Geoplanidae) [lab] (1/4) | |
Unidentified Terrestrial ribbon worm (Nemertea) [lab] (1/1) | |
Land slug Bradybaena similaris (Gastropoda) (1/2) | |
Land slug Deroceras laeve (Müller, 1774) (Gastropoda) [lab] (Suppl. material |
|
Land snail Bradybaena similaris (Férussac, 1821) (Gastropoda) [lab] | |
Obama burmeisteri (Schultze & Müller, 1857) | Land snail Achatina fulica Bowdich, 1822 (Gastropoda) [nat] (Fig. |
Land slug Bradybaena similaris (Férussac, 1821) (Gastropoda) [lab] | |
Obama baptistae (Oliveira & Leal-Zanchet, 2012) | Land snail (Gastropoda) [lab] |
Obama carinata (Riester, 1938) | Land snail (Gastropoda) [lab] |
Land slug Veronicellidae (Gastropoda) [lab, nat] (Fig. |
|
Obama evelinae (Marcus, 1951) | Unidentified land snail [nat] (Fig. |
Obama ferussaci (Graff, 1897) | Land planarian Cephaloflexa bergi (Graff, 1899) (Geoplanidae) [nat] |
Paraba franciscana (Leal-Zanchet & Carbayo, 2001) | Unidentified land leech (Hirudinea, Annelida) [nat] |
Paraba phocaica (Marcus, 1951) | Land snail Happia sp. (Systrophiilidae, Gastropoda) [nat] |
Pasipha tapetilla (Marcus, 1951) | Unidentified millipede [nat] |
Photographs of land planarians feeding under laboratory conditions (1) and in nature (2–9). Orange arrowheads point to prey; blue arrowheads point to the predator flatworm. (1) Obama anthropophila capturing Issoca rezendei. Note the body margins bending onto the prey, thus preventing it from escaping even before being eaten (inset); (2) a young specimen of Obama burmeisteri feeding on the giant African snail (Ilhabela, SP); (3) Obama carinata handling a slug (Veronicellidae) (Parque Estadual da Serra da Cantareira, São Paulo, SP); (4) Cephaloflexa bergi eating a harvestman (Reserva Biológica Augusto Ruschi, ES); (5) Geobia subterranea eating an earthworm (Caxambu, MG); (6) Geoplana cf. chita disturbed while eating a snail to show the shell (São Sebastião, SP); (7) two specimens of Imbira marcusi simultaneously attacking an earthworm (Parque Estadual Intervales, SP); (8) Notogynaphallia cf. sexstriata eating an insect larva (Parque Estadual da Serra do Mar, SP); (9) Obama evelinae eating a land snail (Reserva Natural Municipal Nascentes de Paranapiacaba, Santo André, SP).
Invertebrates not eaten by species of Geoplaninae land planarians in laboratory conditions, presented here for the first time. If available, number of experiments is given in parentheses.
Land flatworm species | Invertebrate not eaten |
---|---|
Geoplana quagga Marcus, 1951, incertae sedis | Unidentified woodlice (Oniscidea, Crustacea) |
Unidentified millipede (Diplopoda) | |
Unidentified springtail (Collembola, Hexapoda) | |
Unidentified earthworm (Oligochaeta) | |
Unidentified ant (Formicidae, Insecta) | |
Unidentified land snail (Gastropoda) | |
Imbira marcusi |
Unidentified land snail (Gastropoda) |
Unidentified springtail (Collembola, Hexapoda) | |
Issoca rezendei (Schirch, 1929) | Unidentified earthworm (Oligochaeta) |
Unidentified land snail (Gastropoda) | |
Unidentified torn slug (Gastropoda) | |
Unidentified torn springtail (Collembola, Hexapoda) | |
Unidentified millipede (Diplopoda) | |
Luteostriata ernesti (Leal-Zanchet & E. M. Froehlich, 2006) | Unidentified ant (Formicidae, Insecta) |
Unidentified land snail (Gastropoda) | |
Unidentified torn springtail (Collembola, Hexapoda) | |
Unidentified earthworm (Oligochaeta) | |
Unidentified millipede (Diplopoda) | |
Unidentified land slug (Veronicellidae, Gastropoda) | |
Unidentified earthworm (Oligochaeta) | |
Unidentified woodlice (Oniscidea, Crustacea) | |
Unidentified millipede (Diplopoda) | |
Unidentified larva of Mycetophilidae (Insecta) | |
Unidentified larva of Microlepydoptera (Insecta) | |
Obama anthropophila | Land planarian Obama burmeisteri (Schultze & Müller, 1857) (4) |
Unidentified Veronicellidae (Gastropoda) (1) | |
Unidentified larva of Microlepidoptera (Insecta) (1) | |
Unidentified larva of Mycetophilidae (Insecta) (1) | |
Unidentified land isopod (Oniscidea) (3) | |
Unidentified earthworm (Oligochaeta) (4) | |
Obama braunsi (Graff, 1899) | Unidentified earthworm (Oligochaeta) |
Unidentified woodlice (Oniscidea, Crustacea) | |
Obama burmeisteri (Schultze & Müller, 1857) | Unidentified woodlice (Oniscidea, Crustacea) |
Unidentified ant (Formicidae, Insecta) | |
Obama nungara Carbayo, Álvarez-Presas, Jones & Riutort, 2016 | Unidentified, very juvenile land snail (Helicidae, Gastropoda) |
Pasipha pasipha (Marcus, 1951) | Unidentified land snail (Gastropoda) |
Unidentified earthworm (Oligochaeta) | |
Unidentified woodlice (Oniscidea, Crustacea) | |
Unidentified ant (Formicidae, Insecta) | |
Xerapoa pseudorhynchodemus (Riester, 1938) | Unidentified earthworm (Oligochaeta) |
Unidentified torn land slug (Gastropoda) | |
Unidentified land snail (Gastropoda) | |
Unidentified springtail (Collembola, Hexapoda) | |
Unidentified millipede (Diplopoda) | |
Unidentified ant (Formicidae, Insecta) |
Apparently, geoplaninids prey on a wide range of taxonomic groups, including snails, slugs (Mollusca: Gastropoda), acari, harvestmen (Arthropoda: Arachnida), woodlice (Arthropoda: Crustacea), adult and larval stages of insects (Arthropoda: Hexapoda), land planarians (Platyhelminthes: Tricladida), land leeches, earthworms (Annelida: Oligochaeta), and terrestrial ribbon worms (Nemertea). Some land flatworm species only feed on organisms of one taxonomic group (e.g., Gastropoda, Opiliones), whereas others display wider diet breadth. The former are called ‘specialists’, and the latter ‘generalists’, according to the
Obama anthropophila is a generalist predator. In addition to preying on thirteen species across three phyla, Platyhelminthes, Nemertea, and Mollusca, its diet also includes exotic species.
Only a few other flatworms are known to be generalists. The New Guinea rhynchodeminid, Platydemus manokwari preys on mollusks, earthworms, woodlice, flatworms and terrestrial ribbon worms (
The results summarized in this work suggest that the diets of closely related species, i.e., species of the same genus, tend to be similar. In a study of mollusk predation by land planarians,
In species of Luteostriata, prey capture is facilitated by the combined action of sticky mucus secretion and the sucker-like action of the ventral side of the cephalic extremity (
To date, Cephaloflexa bergi, C. araucariana and Choeradoplana crassiphalla Negrete & Brusa, 2012, are the only planarian species known to feed on harvestmen. Interestingly, these two genera are sister groups. When crawling, the anterior extremity of these flatworms is curled up (
Species of Choeradoplana and Cephaloflexa also show cephalic muscle specializations, but unlike Luteostriata and close relatives, the muscle fibers of the retractor run ventrally along the antero-posterior axis of the body. In this respect, Choeradoplana and Cephaloflexa differ from each other in some morphological details (see details in
Most species of Obama prey on gastropods (Tables
The wide diet breath of these snails might facilitate their dispersal by humans and their subsequent colonization of new habitats. For instance, the generalist species O. anthropophila and O. nungara have colonized new habitats. Conversely, O. ladislavii is a diet-specialist that has a relatively great potential to become an invasive species, since it is tolerant to variation in environment (
Finally, despite the non-quantitative nature of the records, the food preferences of species within the genera Geoplana, Matuxia and Xerapoa, reinforce the hypothesis that diet specializations happens within the taxonomic groups of snails, insect larvae and arthropods, respectively (Tables
Although our observations should simply be considered as working hypotheses, they seem to support the idea that “ecological and behavioral change in geoplaninids is more conservative than phylogenetic diversification,” as pointed out by
We are grateful to the Administration of Parque Ecológico do Tietê for allowing invertebrate sampling. We thank José Horacio Grau for making Fig.