Tag Archives: land planarians

by | March 26, 2014 · 6:06 pm

The lack of taxonomists and its consequences on ecology

by Piter Kehoma Boll

ResearchBlogging.orgI have already written on the problems of taxonomy in small and not-so-cute groups in a previous post, where I talked about the fact that several species, after being described, are completely ignored for decades or centuries. Here I will focus on the other extreme: the species yet to be described.

This is not a very big problem in very well studied groups, such as vertebrates and flowering plants, but less attractive groups, like worms, suffer a lot by the lack of taxonomists. I am going to use land planarians as an example, again, since it is the group that I work with.

Land planarians have been shown to be important predators of invertebrates in forests, as well as good indicators about the degree of disturbance in those ecosystems, but most species are still unknown. Only in Brazil, more than a hundred species have been described only for the Atlantic Rainforest and possibly at least an equal number is yet unknown. The situation is even worse in other regions of the country or neighbouring countries, where there are almost no species described at all.

Despite this small knowledge of the group, eventually some works regarding community structure are published, where a list of land planarians from the study site is presented. Let’s take a look at some of those lists:

1. Species of land planarians in four different habitats of the National Forest of São Francisco de Paula, southern Brazil. In Carbayo et al., 2001:

Carbayo et al. 2001

There are 28 distinguished species, but only one identified (Geoplana ladislavii), one not sure (Geoplana pavani) and two with the same name, but refering to different species (Notogynaphallia marginata). The others were yet unknown.

 

2. Species of land planarians in four different habitats of the National Forest of São Francisco de Paula, southern Brazil. In Carbayo et al., 2002:

Carbayo et al., 2002

A similar table, in the same area, by the same authors, about one year later. We can see 3 new species in the study: Geoplana franciscana, Geoplana josefi and Notogynaphallia guaiana, which were described in 2001. They were probably among the species listed in the first study, but which of them? Was Geoplana franciscana the species assigned as Geoplana sp.1, Geoplana sp.2, Geoplana sp.3…?

 

3. Abundance of species of land planarians in Araucaria Forest of the National Forest of São Francisco de Paula, southern Brazil. In Antunes et al., 2012.

Antunes et al., 2012

The same area again, 10 years later. We can see that there are more species already described, but many more still awaiting a name.

 

When we consider a single study about ecological communities by itself, the fact that the species found are not named is not such a big deal, since the main purpose is to measure patterns of abundance, richness and diversity and the interaction of biotic and abiotic factors on the communities. However, when comparing studies, the unidentified species become simply useless data. How can you be certain about what Geoplana sp.5 is in each study?

We urgently need more taxonomists working on those less prestigious groups, so that our ecological studies may have a wider role in conservation and understanding of nature.

–  – –

References:

Antunes, M., Leal-Zanchet, A. M. & Fonseca, C. 2012. Habitat structure, soil properties, and food availability do not predict terrestrial flatworms occurrence in Araucaria Forest sites. Pedobiologia, 55 (1), 25-31 DOI: 10.1016/j.pedobi.2011.09.010

Carbayo, F., Leal-Zanchet, A. M. & Vieira, E. M. 2001. Land planarians (Platyhelminthes, Tricladida, Terricola) as indicators of man-induced disturbance in a South Brazilian rainforest. Belgian Journal of Zoology, 131, 223-224

Carbayo, F., Leal-Zanchet, A. M. & Vieira, E. 2002. Terrestrial flatworm (Platyhelminthes: Tricladida: Terricola) diversity versus man-induced disturbance in an ombrophilous forest in southern Brazil. Biodiversity and Conservation, 11 (6), 1091-1104 DOI: 10.1023/A:1015865005604

Sluys, R. 1998. Land Planarians (Platyhelminthes, Tricladida, Terricola) in biodiversity and conservation studies. Pedobiologia, 42, 490-494

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by | March 19, 2014 · 2:42 pm

What on Earth is Leimacopsis terricola? A flatworm mystery.

by Piter Kehoma Boll

ResearchBlogging.orgOh, ye olde times…

The 18th and 19th centuries were well marked by great worldwide expeditions by naturalists aboard ships travelling all around the world. Charles Darwin is certainly the most famous of them, but he was not the only one.

One of those naturalists was Karl Ludwig Schmarda, born in 1819. He studied in Vienna and was later a professor at the University of Graz, Austria. From 1853 to 1857, he travelled around the world investigating several locations and collecting primarily invertebrates. After his return, he published a work entitled Neue wirbellose Thiere beobachtet und gesammelt auf einer Reise um die Erde 1853 bis 1857 (New invertebrate animals observed and sampled on a travel around the Earth, 1853 to 1857).

Among the countless animals that he described, there was a worm which he called Prostheceraeus terricola. The description is as it follows:

Prostheceraeus terricola. Schmarda.
Taf. VI. Fig. 69.

Char. : Corpus oblongo-lanceolatum. Dorsum convexum viride. Fascia mediana et margo purpureus. Tentacula subuliformia.

Der Körper ist weniger flach als in andern Planarien, länglich, hinten lanzettförmig zugespitzt, vorne beinahe quer abgeschnitten. Die Fühler sind kurz und pfriemenförmig zugespitzt. Der Rücken ist stark convex, fast grasgrün, mit einer purpurrothen Längslinie nach seinem ganzen Verlaufe. Der Rand nicht wellenförmig, purpurroth gesäumt. Die Hauchfläche ist grünlichgrau. Die Länge 20mm, grösste Breite 5mm. Die Augen sind am innern Rande und der Basis der Fühler. Die Gruppe im Nacken, habe ich nicht beobachtet. Die Mundöffnung ist im vordern Drittel. Die Geschlechtsöffnungen habe ich nicht aufgefunden.
Der Grund meiner unvollständigen Kenntniss dieser Thierform ist der Umstand, dass ich nur ein Exemplar in dem obern Theile des Quindiu-Passes ober der Region der Bergpalmen gefunden hatte, welches ich in Gallego skizzirte, das aber schon zu Grunde gegangen war, als ich es in meiner Abendstation in Tocho einer wiederholten nähern Prüfung unterziehen wollte.

In English:

Oblong-lanceolate body. Green convex dorsum. Median and marginal purple stripes. Awl-like tentacles.

The body is less flat than in other planarians, elongated, behind pointed and lanceolate, front almost transversally cut. The feelers are short and awl-like pointed. The back is strongly convex, almost grass green with a purple line running fully along it. Margin not wave-like and purple-colored. The ventral surface is greenish gray. Length 20mm, largest width 5mm. The eyes are at the inner border and the base of the feelers. The group at the neck I didn’t observed. The mouth opening is in the front third. The sexual opening I did not found.
The reason of my incomplete knowledge of this animal form is due to the circumstance of finding only one specimen in the top part of the Quindiu passage above the region of the mountain palms, which I sketched it in Gallego, since it was already deteriorating, to undergo a revision back at the station in Tocho.

Here you can see the drawing of the animal:

Drawing of Prostheceraeus terricola by Schmarda, 1859

Drawing of Prostheceraeus terricola by Schmarda, 1859

Schmarda put other worms in the same genus, all of them marine. The genus is valid until today for marine species and they are classified as belonging to the Polycladida, those beautiful sea flatworms.

In fact, this animal actually looks kind of similar to a polyclad, but Schmarda found it on the top of the mountains! Quite unusual, and unfortunately he found only one single specimen.

Prostheceraeus giesbrechtii, another species described by Schmarda (1859). Photo by Parent Géry taken from commons.wikimedia.org

Prostheceraeus giesbrechtii, another species described by Schmarda (1859). Photo by Parent Géry taken from commons.wikimedia.org

Later, in 1862, K. M. Diesing made a revision of turbellarians and defined that, as the creature lived on land, it was certainly something other than a polyclad and changed it to a new genus which he called Leimacopsis (slug-like):

XVIII. LEIMACOPSIS DIESING.
Prostheceraei spec. Schmarda.

Corpus elongato-lanceolatum, supra convexum. Caput corpore continuum antice truncatum, tentaculis duobus genuinis frontalibus. Ocelli numerosi tentaculorum. Os ventrale antrorsum situm, oesophago… Apertura genitalis. . . Terrestres, Americae tropicae.

1. Leimacopsis terricola DIESING.
Corpus elongato-lanceolatum, supra convexum, viride, vitta mediana corpori aequilonga et marginibus haud undulatis purpureis, subtus viridi-cinereum. Tentacula subuliformia, brevia. Ocelli ad marginem internum et ad basim tentaculorum. Os in anteriore corporis tertia parte. Longit. 10′”, latit. 2 1/3 “.
Prostheceraeus terricola Schmarda: Neue wirbell. Th. I. 1. 30. Tab. VI. 69.
Habitaculum. In parte superiore transitus Andium Quindiu, supra regionem Palmarum montanarum (Bergpalmen), specimen unicum (Schmarda).

It’s basically a repetition of Schmarda’s description and based only on it. It looks that no other specimens were found until this time.

Years later, in 1877, H. N. Moseley published a catalogue of all land planarians known at the time. He included Leimacopsis terricola with the following description:

Family. — Leimacopsidæ, Diesing.

Genus Leimacopsis. — Diesing, Revision der Turbellarien, Abtheilung Dendrocoelen, Sitzbt. Akad. Wiss., Wien, 1861, p. 488.
Leimacopsis terricola.—Diesing, 1. c.
Prostheraceus terricola. — Schmarda, ‘Neue Wirbellose Thiere,’ Th. 1, 1—30, Tab. VI, fig. 69.
With a pair of true frontal tentacles beset with numerous eyes. Occurs high up in the Andes at the pass of Quindiu, above the region of mountain palms.

As you can see, it’s again simply a repetition of Schmarda’s description based on that single specimen from 20 years earlier, but from Diesing on, the animal started to be considered a land planarian rather than a polyclad.

Now in 1899, Ludwig von Graff published his great monography about turbellarians and I’m certain that I saw something about Leimacopsis there. Unfortunately I never found a digital copy of it and I don’t have a physical copy easily accessible either, but according to Ogren (1992), it has only a repetition of Schmarda’s account. Graff, however, changed the spelling to Limacopsis, but this is not valid according to the International Code of Zoological Nomenclature.

In 1914, finally a new article, by O. Fuhrmann, was published with information about land planarians from Colombia. He begins commenting that there were only three species known for the country by that time, one of them being Limacopsis [sic] terricola. However, the species was not found again this time…

The years passed and nothing changed. In 1991, Ogren and Kawakatsu, in part of their index to the species of land planarians, comment that several researchers, like E. M. Froehlich and L. H. Hyman, considered Leimacopsis terricola as possibly being a slug.

In 1992, Robert Ogren wrote an excellent revision of this species, which presents all information I have given here and much more. He concluded that the organism is a species inquerenda (needing further investigation) and nomen dubium (doubtful name). It is not possible to assign the animal as either a flatworm or a mollusk, or anything else due to the lack of information. Ogren considered it as “clearly part of the lore of Cryptozoology”.

As we can see, cryptids don’t need to be big animals like dinosaurs or big feet. Even a small slug-like worm from the Andes may fit.

Leimacopsis terricola is certainly an interesting organism. What was it really? Was it real? Maybe an extensive research in the area would reveal something… or not. Let’s wait and hope… Or perhaps… what about going to an adventure in Colombia’s Andean region in search of the mysterious creature?

– – –

References:

Diesing, K. M. 1862. Revision der Turbellarien. Abtheilung: Dendrocoelen. Keiserlich-Königlichen Hof- und Staatsdruckerei DOI: 10.5962/bhl.title.2108

Fuhrmann, O. 1914. Planaires terrestres de Colombie. In: Fuhrmann & Mayor (eds.) Voyage d’Exploration Scientifique en Colombie. Mémoires de la Société des sciences naturelles de Neuchâtel, 5 (2), 748-792

Moseley, H. 1874. On the Anatomy and Histology of the Land-Planarians of Ceylon, with Some Account of Their Habits, and a Description of Two New Species, and with Notes on the Anatomy of Some European Aquatic Species. Philosophical Transactions of the Royal Society of London, 164, 105-171 DOI: 10.1098/rstl.1874.0005

Ogren, R. E. 1992. The systematic position of the cryptic land organism, Leimacopsis terricola (Schmarda, 1859)(olim Prostheceraeus)(Platyhelminthes). Journal of The Pennsylvania Academy of Science, 66 (3), 128-134

Ogren, R. E. & Kawakatsu, M. 1991. Index to the species of the family Geoplanidae (Turbellaria, Tricladida, Terricola) Part II: Caenoplaninae and Pelmatoplaninae. Bulletin of Fuji Women’s College, 29, 35-58

Schmarda, L. K. 1859. Thiere beobachtet und gesammelt auf einer Reise um die Erde 1853 bis 1857. Lepizig: W. Engelmann. DOI: 10.5962/bhl.title.14426

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by | June 1, 2013 · 12:01 am

Earthling Bulletin #17

by Piter Kehoma Boll

Skull of Jianchangosaurus yixianensis, a new therizinosaur from China with an unusual dentition. Photo extracted from Pu et al. 2013. doi:10.1371/journal.pone.0063423.g003

Skull of Jianchangosaurus yixianensis, a new therizinosaur from China with an unusual dentition. Photo extracted from Pu et al. 2013. doi:10.1371/journal.pone.0063423.g003

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by | October 30, 2012 · 7:28 pm

Unknown whereabouts: the lack of biogeographical references of species

by Piter Kehoma Boll

ResearchBlogging.org Biogeography, as you may know, is the study of the distribution of species or ecosystems through the planet. The knowledge which comes from biogeographical surveys is valuable information for other areas, like ecology, evolutionary biology, geology and paleontology, as well as for conservation purposes. Knowing the distribution of a species may help to determine places of higher priority for conservation, as well as helping to trace an evolutionary pathway or even to determine an ancient geological event.

Despite all this advantages coming from biogeographical studies, many species have a sparse distribution record, or don’t have any at all. That’s more usual concerning “less attractive” groups, like, for example, worms or mosses, which don’t have many researchers interested in them.

I will give here an example among a species I work with. It’s a land planarian, of course; what else could it be? Anyway, the species I’m talking about is called Geoplana marmorata. Here you can see a picture of it:

Geoplana marmorata Schultze & Müller, 1857 from Santa Maria, Rio Grande do Sul, Brazil. Photo by Piter Kehoma boll.

G. marmorata was described in 1857 by Schultze & Müller based on material coming from Blumenau, a city in the state of Santa Catarina, southern Brazil. Later, Graff, in 1899, misidentified it as a variety of Geoplana rufiventris, another species described by Schultze & Müller in the same paper as G. marmorata. This misidentification happened probably due to the specimens examined by Graff being old ones which were kept too much time in a preservative medium, probably ethanol, making them lose their original color as when alive.

About 50 years later, in 1959, C. G. Froehlich corrected this mistake and also expanded its distribution for a new location, Rio do Testo, not that far from Blumenau. In 1967, C. G. Froehlich again expanded its known distribution to include Argentina.

There are no further publications concerning the distribution of G. marmorata, except for a paper by E. M. Froehlich, from 1978, about a Chilean species, G. caleta, which resembles G. marmorata both in external and internal morphology, but the minor differences and the great distance separating both groups seem to point to different species, though probably closely related phylogenetically.

Anyway, so concerning only what’s now found through papers, G. marmorata is only know to happen in Argentina and the Brazilian state of Santa Catarina. Well, here I say that its distribution is far greater.

Despite not being recorded in any species survey in forest remains of Rio Grande do Sul, Brazil’s southernmost state, G. marmorata is indeed found there. We, researchers from Instituto de Pesquisa de Planárias, Unisinos, know this species very well since it is found very frequently in urban environment in the metropolitan area of Porto Alegre, as well as in Santa Maria, a city in the center of the state.

I was kind of shocked as I figured out that there are no publications regarding its presence in Rio Grande do Sul. This just made me wonder about how much scientists know and, as it seems so obvious and natural, they don’t publish it, so retaining essential knowledge, which could be so useful to other researches, simply because of some lack of attention.

This has motivated me to write a paper updating the distribution of land planarian species from Rio Grande do Sul as soon as I have time, based on our protocol records at Instituto de Pesquisa de Planárias. And as a final request, I ask to those who work with research to pay attention to those subjects, so that they don’t get neglected as much.

– – –

References:

Froehlich, C. G. 1959. On Geoplanids from Brazil. Boletim da Faculdade de Filosofia, Ciências e Letras da Universidade de São Paulo, Série Zoologia, 22, 201-265

Froehlich, C. G. 1967. A contribution to the zoogeography of neotropical land planarians. Acta Zoologica Lilloana, 23, 151-162

Froehlich, E. M. 1978. On a collection of Chilean landplanarians Boletim da Faculdade de Filosofia, Ciências e Letras da Universidade de São Paulo, Série Zoologia, 3, 7-80

Graff, L. v. 1899. Monographie der Turbellarien. II. Tricladida Terricola. Engelmann, Leipzig, 574 p.

Schultze, M., & Müller, F. 1857. Beiträge zur Kenntnis der Landplanarien. Abhandlungen der Naturforschenden Gesellschaft zu Halle, 4, 61-74

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by | August 10, 2012 · 2:09 am

How are little flatworms colored? A Geoplana vaginuloides analysis

by Piter Kehoma Boll

ResearchBlogging.org As you already know, I work with land planarians, so there’s nothing more natural than seeing me talking about them. Today I’ll make a brief comment about the type species of the genus Geoplana which gives name to the family Geoplanidae (the land planarians themselves).

Geoplana vaginuloides was originally described by Charles Darwin in 1844 under the name Planaria vaginuloides. His description was based only on external morphology, which today is considered insufficient to describe correctly a land planarian. Later Stimpson (1857) moved it to his new genus Geoplana, but still only external features were used. By that time, no type species had been assigned to the genus and E. M. Froehlich (1955) decided to choose Geoplana vaginuloides (Darwin, 1844) as the type species for being the first one found by Darwin and one of the species put in the genus Geoplana by Stimpson when he described it.

It was only in 1990 that a good revision of land planarians was made by Ogren and Kawakatsu and the internal morphology, especially that of the copulatory apparatus, started to have a greater importance in describing a species correctly. Based on Geoplana vaginuloides, they defined the genus Geoplana as follows:

“Geoplanidae of elongate body form; creeping sole broader than a third of the body width; strong cutaneous longitudinal muscles; mc:h value from 4%-8%; parenchymal longitudinal musculature weak or absent, not in a ring zone; testes are dorsal; penis papilla present; female canal enters genital antrum dorsally; cephalic glandulo-muscular organs, sensory papillae and adenodactyls absent.” (Ogren & Kawakatsu, 1990).

As noticed by Riester (1938), G. vaginuloides possesses a very long penis papilla invading the female antrum, as well as other peculiar features. These aspects were important to consider a land planarian found by Marcus in 1951 as belonging to this species, even though it had external colors almost inverted when compared to the specimen described by Darwin.

Using the internal morphology to assure that all the following descriptions of land planarians belong to a single species, Geoplana vaginuloides, we can find at least 4 different external color patterns to this species:

  •  Darwin 1844:  “Ocelli numerous, placed at regular intervals on the anterior extremity; irregularly, round the edges of the foot. […] Sides of the foot coloured dirty “orpiment orange”; above, with two stripes on each side of pale “primrose-yellow,” edged externally with black; on centre of the back a stripe of glossy black; these stripes become narrow towards both extremities.”
    Locality: Rio de Janeiro, Brazil
  •  Riester, 1938: “Unterseite und Körperänder weinrot, dann zwei schmale gelbe Streifen und in der Rückenmitte ein tief Schwarz glänzendes breites Band.” (Underside and body edges wine red, then two narrow yellow stripes and in the middle of the back a deep black shiny broad band.)
    Locality: Teresópolis/Guapimirim, Rio de Janeiro, Brazil
  • Marcus, 1951: “A faixa mediana é ocre, na maior parte da extensão. Anterior e posteriormente é preta. Flanqueiam-na faixas amarelas claras, cada uma tão larga quão a mediana. As zonas dorso-laterais são pretas com pontinhos claros, que não são olhos. O ventre é claro.” (The median band is ochre in most of its length. Anteriorly and posteriorly it’s black. Light yellow bands flank it, each one as broad as the median one. The dorsolateral zones are black with white spots, which aren’t eyes. The venter is light.)
    Locality: Eldorado, São Paulo, Brazil
  • C. G. Froehlich, 1958: “The colour pattern is similar to type C of Marcus (1952, pp. 76-77, pl. 23 fig. 136) but the median reddish stripe is broader (about 1 mm. across, just in front of the pharynx), and both the black and the white stripes that follow on each side are narrower (about 0.2 to 0.3 mm broad each, in the same region). The median stripe begins at 2.5 mm from the anterior tip. The creeping sole is greyish white.”
    Locality: Itanhaém, São Paulo, Brazil

Different color patterns in Geoplana vaginuloides according do Darwin, 1844 (1), Riester, 1938 (2), Marcus, 1951 (3) and C. G. Froehlich, 1958 (4)

Location of the 4 morphotypes seen in the picture above. Image made on Google Earth.

Along with those descriptions, Prudhoe (1949), found an animal in Trinidad with the same external description given by Darwin, but its internal structure was very different from Riester (1938). So it was probably a different species.

About photographs of this species, I found only the three seen below. They all belong to specimens with a color pattern close to those described by Marcus and Froehlich. It would be interesting to find an animal with the color pattern from the original description by Darwin!

Geoplana vaginuloides (Darwin, 1844). Photo by Fernando Carbayo. Extracted from each.uspnet.usp.br/planarias/

Geoplana vaginuloides (Darwin, 1844). Photo by Fernando Carbayo. Extracted from each.uspnet.usp.br/planarias/

Geoplana vaginuloides (Darwin, 1844). Notice that this one doesn’t have the black border flanking the median orange band. Photo by Instituto Rã-Bugio. Extracted from http://www.ra-bugio.org.br

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References:

Darwin, C. 1844. Brief Description of several Terrestrial Planariae, and of some remarkable Marine Species, with an Account of their Habits. Annals and Magazine of Natural History, Annales des Sciences Naturelles, 14, 241-251

Froehlich, E. M. 1955. Sobre Espécies Brasileiras do Gênero Geoplana. Boletim da Faculdade de Filosofia, Ciências e Letras da Universidade de São Paulo, Série Zoologia, 19, 289-339

Froehlich, C. G. 1958. On a Collection of Brazilian Land Planarians. Boletim da Faculdade de Filosofia, Ciências e Letras da Universidade de São Paulo, Série Zoologia, 21, 93-121

Marcus, E. 1951. Turbellaria Brasileiros. Boletim da Faculdade de Filosofia, Ciências e Letras da Universidade de São Paulo, Série Zoologia, 16, 5-215

Ogren, R. E. & Kawakatsu, M. 1990. Index to the species of the family Geoplanidae (Turbellaria, Tricladida, Terricola) Part I: Geoplaninae. Bulletin of Fuji Women’s College, 28, 79-166

Prudhoe, S. 1949. Some roundworms and flatworms from the West Indies and Surinam. – IV. Land Planarians. Journal of the Linnean Society of London, Zoology, 41 (281), 420-433 DOI: 10.1111/j.1096-3642.1940.tb02415.x

Riester, A. 1938. Beiträge zur Geoplaniden-Fauna Brasiliens. Abhandlungen der senkenbergischen naturforschenden Gesellschaft, 441, 1-88

Stimpson, W. 1857. Prodromus descriptionis animalium evertebratorum quæ in Expeditione ad Oceanum, Pacificum Septentrionalem a Republica Federata missa, Johanne Rodgers Duce, observavit er descripsit. Pars I. Turbellaria Dendrocœla. Proceedings of the Academy of Natural Sciences of Philadelphia, 19-31

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by | June 29, 2012 · 5:21 pm

Friday Fellow: Abundant Yellow-Striped Flatworm

by Piter Kehoma Boll

Leia em português

Today our Friday Fellow is an almost unknown species from an almost unknown group: Luteostriata abundans (formerly Notogynaphallia abundans) is a land planarian (a flatworm) found in southern Brazil, mainly in urban areas. It’s common to find it around in gardens and parks, hidden under leaves, stones and logs.

Two planarians Luteostriata abundans, named by me as Pierre and Marie (don’t forget they are hermaphrodites, though). Photo by Piter Kehoma Boll.

Most land planarians are very poorly known, even though they are recognized as good bio-indicators of conservation. However, there is an article published about the feeding habits of L. abundans (Prasniski & Leal-Zanchet, 2009). Currently it’s only known that it feeds on woodlice, but since it’s a very common species in disturbed areas, its diet probably includes something else. (I’m studying the predatory behavior of this and other species, but haven’t found any other prey item for it yet…)

Here at IPP (Instituto de Pesquisa de Planárias, in English “Planarian Research Institute”), we are also doing research about the regeneration of L. abundans. Everybody knows how well freshwater planarians can regenerate when cut into several pieces. Land planarians don’t seem to be so skilled, but very little is known about them on this subject too!

Another interesting fact that we noticed about L. abundans is their ability to escape from almost every container you put them into. We need to seal the lid of their plastic containers with adhesive tape and yet they sometimes manage to find a way to leave.

There is so much yet to know about these flatworms. As predators, they are essential to balance the population size of their prey in conserved areas and for those species known to live well in urban places, knowledge of their feeding habits is important to evaluate their chance to become invasive.

– – –

References:

Carbayo, F. 2010. A new genus for seven Brazilian land planarian species, split off from Notogynaphallia (Platyhelminthes, Tricladida) Belgian Journal of Zoology, 140 (Suppl.), 91-101

Prasniski, M. E. T. & Leal-Zanchet, A. M. 2009. Predatory behavior of the land flatworm Notogynaphallia abundans (Platyhelminthes: Tricladida) Zoologia, 26, 606-612 DOI: 10.1590/S1984-46702009005000011

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by | January 30, 2012 · 1:51 pm

Once found and then forgotten: the not so bright side of Taxonomy

by Piter Kehoma Boll

Leia em português

One of the big questions without an answer in our knowledge of the world is “How many species are there on the Earth?” and we are far from having even an approximation of the real number. There are, for sure, thousands of speculations, varying hugely between them, but we could say that a mean value would be about 10 million species, while we currently know only about 1.5 million. And that’s exactly the point I’m interested in focus here: the number of species we currently know. Are we sure that all we consider species are in fact so?

Probably everybody has already heard about a situation where a group of organisms once considered a single species where in fact two distinct ones, like the African elephants Loxodonta africana and L. cyclotis, where the latter was only classified as a distinct species by 2010.

African bush elephant, Loxodonta africana (left) and african forest elephant, Loxodonta cyclotis (right). Photos by Muhammad Mahdi Karim (left), from http://www.micro2macro.net, and Peter H. Wredge (right), extracted from Wikipedia.

As for people in general, if you ask them to say the name of an animal, they would probably tell the name of a mammal, or perhaps a bird, reptile or if you are lucky, they will say “butterfly” or “spider” and that’s all. Well, that’s nothing wrong with it, but I think people should realize that those animals, like lions or elephants, are just a small particle in the entire world of species.

I currently hold an undergraduate research at Unisinos (Universidade do Vale do Rio dos Sinos / University of the Sinos Valley), Brazil, working at the IPP (Instituto de Pesquisa de Planárias / Planarian Research Institute) with land planarians’ ecology, physiology and behavior.

For those who don’t know (and I know there are a lot of people who don’t), land planarians are terrestrial flatworms, belonging to the phylum Platyhelminthes, in the group Tricladida. They are usually found under rocks or logs in forested areas, but also in gardens or elsewhere. Many of them are very sensible to light, high temperatures or extremes of drought and moisture, so that their presence may indicate a more conserved area.

Luteostriata abundans
Two specimens of Luteostriata abundans (Graff, 1899), a land planarian from southern Brazil. Photo by Piter Kehoma Boll.
Geoplana rubidolineata Baptista & Leal-Zanchet, 2006. Photo by Fernando Carbayo, extracted from Baptista & Leal-Zanchet, 2006.

Land planarians are a group still poorly known and, despite a high number of species having been described in the last decades, many more are yet to be, and those already described are not well understood in what concerns their ecology and behavior.

The first described land planarians were defined based only on external features, mainly their body shape, color and eyes arrangement. But Ludwig von Graff, in his 1896 work “Über die Morphologie des Geschlechtsapparates der Landplanarien” (On the Morphology of the Reproductive Apparatus of Land Planarians) already noticed the importance of internal morphology, mainly that of the copulatory apparatus, for a more precise identification at the species level.

Sagittal reconstruction of the copulatory apparatus of Rhynchodemus scharffi Graff, 1896. Extracted from Graff, 1896.

Despite that, the following years were still marked by publications concerning only external features, like the work of Schirch (1929). Only by the 1950’s a real focus was started to be given in the structure of male and female organs. Most of the following works on land planarians’ descriptions, like those of the Marcus and Froehlich couples, focused on the copulatory apparatus together with external features, so giving a more trustful description of new species. By this moment, the reproductive structures became essential for the classification of new species and eventually led to the creation of new genera.

Drawing of several land planarian species. Extracted from Schirch, 1929.
Marcus 1951
Drawings of internal and external structure of several land planarians. Extracted from Marcus, 1951.

In 1990, Ogren and Kawakatsu published an index of all known species of land planarians in family Geoplanidae by that time. They noticed that many species still classified in the genus Geoplana, like those described by Schirch, were never reviewed and were still only known by external features, so that their position within Geoplana may not be correct. To avoid this misclassification, they created a new “temporary genus”, which they called Pseudogeoplana (false Geoplana) and put all those dubious species in it to stay there until someone reviewed them and could place them in the correct genus, either the original Geoplana or other one.

But guess what? Ogren and Kawakatsu did that in 1990 and now we are in 2012 and the situation remains the same. Those poor planarians species are still waiting in that taxonomic shelter until someone moves them to the place they belong to.

So how can we be sure about anything from those species? They were described in 1929, almost a century ago, and no one cared about them since then. And I guess the same occurs in other less cute and attractive groups, so while we describe hundreds or thousands of new species every year, other hundreds or thousands are left behind, forgotten inside dusty glasses in the zoological museums worldwide.

I just hope it will change someday.

Thanks for reading.

For more about systematics, you might want to see:

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References:

Baptista, V. & Leal-Zanchet, A. 2005. Nova espécie de Geoplana Stimpson (Platyhelminthes, Tricladida, Terricola) do sul do Brasil. Revista Brasileira de Zoologia, 22 (4), 875-882 DOI: 10.1590/S0101-81752005000400011

Du Bois-Reymond Marcus, E. 1951. On South American Geoplanids. Boletim da Faculdade de Filosofia, Ciências e Letras da Universidade de São Paulo, Série Zoologia, 16, 217-256.

Froehlich, E. M. 1955. Sobre Espécies Brasileiras do Gênero Geoplana. Boletim da Faculdade de Filosofia, Ciências e Letras da Universidade de São Paulo, Série Zoologia, 19, 289-339.

Graff, L. v. 1896. Über die Morphologie des Geschlechtsapparates der Landplanarien. Verhandlungen der Deutschen Zoologischen Gesellschaft, 73-95.

Marcus, E. 1951. Turbellaria Brasileiros. Boletim da Faculdade de Filosofia, Ciências e Letras da Universidade de São Paulo, Série Zoologia, 16, 5-215.

Mora, C., Tittensor, D., Adl, S., Simpson, A. & Worm, B. 2011. How Many Species Are There on Earth and in the Ocean? PLoS Biology, 9 (8) DOI: 10.1371/journal.pbio.1001127

Ogren, R. E. & Kawakatsu, M. 1990. Index to the species of the family Geoplanidae (Turbellaria, Tricladida, Terricola) Part I: Geoplaninae. Bulletin of Fuji Women’s College, 28, 79-166.

Rohland, N., Reich, D., Mallick, S., Meyer, M., Green, R., Georgiadis, N., Roca, A. & Hofreiter, M. 2010. Genomic DNA Sequences from Mastodon and Woolly Mammoth Reveal Deep Speciation of Forest and Savanna Elephants. PLoS Biology, 8 (12) DOI: 10.1371/journal.pbio.1000564

Schirch, P. F. 1929. Sobre as planarias terrestres do Brasil. Boletim do Museu Nacional, 5, 27-38.

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