MARVELLOUS MANTELLA – Natural History, Husbandry & Reproduction of the Malagasy Poison Frogs.

MARVELLOUS MANTELLA
Natural History, Husbandry & Reproduction of the Malagasy Poison Frogs.
By Joshua S. Ralph

 

Contents:

  • Introduction.
  • Natural History & General Physiology of the Genus.
    • Taxonomy.
    • General Distribution Range.
    • General Appearance.
    • Toxicity of Malagasy Poison Frogs.
    • General Behaviour and Territoriality.
    • General Reproduction and Courtship.

 

INTRODUCTION

Exotic species of fauna such as Reptiles, Amphibians, Invertebrates, Birds and even Fish have both fascinated and intrigued humans for centuries with menageries dating back to the thirteenth century and possibly even further. This is especially true regarding the specific field of Zoology known as Herpetology (taken from the Greek ‘Herpeton’ – “Creeping Animals” and ‘Logia’ – “Knowledge”) – the study of Reptilia and Amphibia – which in the present day millions of people practice as a career and also as a hobby where all manner of species are kept within a captive setting. Many species that are kept, especially with Amphibians, are not only interesting from a behavioural view but also provide a wide kaleidoscope of various colourations and morphological patterns which are highly attractive and capture the imagination of the human mind. Of course, in most species this is a defensive mechanism referred to as ‘Aposematism‘ , which when you translate from Greek means “Warning Colouration”, which is either a product of their toxicity or a mimicry behaviour to show such abilities off regardless of not actually being toxic.

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Fig. 1 Phantasmal Poison Frog (Epipedobates tricolor) male calling, quite a popular species to keep in captivity. © 2013 – Joshua Ralph – All Rights Reserved.

The most obvious examples for this extreme defensive display, is the Neo-tropical family of Dendrobatidae, or commonly known as Poison Dart/Arrow Frogs which cover nearly 300 species over 18 different genera, and even these have numerous quantities of wild morphological variations. Literally far too many to actually be able to list here. This particular family is certainly one of the most popular inhabitants to keep within the terrarium in modern day keeping and  because of this, they are extensively researched as well as intensively bred to accommodate the demand of the International Pet Trade. In recent years, another genus of brilliantly coloured Anura (Frogs & Toads) have started to appear, more commonly, within private and zoological collections alike. This is the genus known as Mantella, the Malagasy ‘counterpart’ to the Neo-tropical Poison Dart Frog family.

These utterly beautiful and curiously intriguing little gems from the island of Madagascar, in the past have not received nearly as much attention, study or even a significant effort in the breeding of each species within a captive environment. Because of this lack of knowledge and efforts, specimens were extensively collection from the wild to satisfy the demand for them, for some of the species such as the Harlequin Mantella (Mantella cowanii) this has proved more than taxing with populations slowly disappearing and becoming smaller and smaller with each passing year.

 

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Fig. 2 Yellow Mantella (Mantella crocea) exhibits quite a few different colourations in the wild. © 2014 – Joshua Ralph – All Rights Reserved.

Personally, it is my hope that more people will take an interest in this particular genus and study their husbandry, behaviour and even start to breed them more extensively to help reduce the strain on the remaining populations in the wild. I have dedicated most of my life to the husbandry and accumulation of knowledge for these amphibians and would like to present this information for everyone, those who already keep species in captivity to people who are looking into working with them . But not only that, but to also raise awareness of the struggle some of these animals face and the conservation efforts in place to preserve them.


NATURAL HISTORY  & GENERAL PHYSIOLOGY OF THE GENUS

TAXONOMY

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Fig. 3 Alfred Grandidier, 1888.

In regards to Mantella, they are a perfect example and product of what is known as convergent-evolution – the individual evolution of a similar trait with  species of a different lineage – sharing huge similarities to Dendrobatidae from Latin America with size, appearance and also some aspects of their behaviour. Like stated above however, they are in no means related to their neo-tropical counterparts, but during the early description of the first specimens from 1866-1872, Alfred Grandidier a  famous French naturalist and taxonomist, described what is believed to be the Brown Leaf Mantella (Mantella betsileo) and placed it within the Dendrobates genus based upon their close resemblance with them. Of course, the entire placement of these new species was ambiguous and heavily debated but,  eventually time passed and in 1882 the genus of Mantella was created by George Albert Boulenger FRS, yet they were still incorrectly placed within the Dendrobatidae family. More and more species were discovered, and with it the phylogenetic categorisation of the genus expanded to what it is in the present say, containing sixteen species, each of which have their own colourations, behavioural traits and even environmental needs.

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Fig. 4 Brown Leaf Mantella (Mantella betsileo) was the first member of the genus now known as Mantella, to be described in 1872, under the original name of Dendrobates betsileo. © 2013 – Joshua Ralph – All Rights Reserved.

The species that are currently found within the genus, who described them and when they were discovered chronologically, is as follows (Please note that not all information, such as names,  can be found regarding the taxonomists etc):

  • Brown Leaf Mantella (Mantella betsileo) – Alfred Grandidier, 1872.
  • Madagascan Mantella (Mantella madagascariensis) – Alfred Grandidier, 1872.
  • Ebenau’s Mantella (Mantella ebenaui) – Oskar Boettger, 1880.
  • Harlequin Mantella (Mantella cowanii) – George Albert Boulenger FRS, 1882.
  • Baron’s Mantella (Mantella baroni) – George Albert Boulenger FRS, 1888.
  • Golden Mantella (Mantella aurantiaca) – François Mocquard, 1900.
  • Climbing Bamboo Mantella (Mantella laevigata) – Paul Ayshford Methuen & John Hewitt, 1913.
  • Beautiful Mantella (Mantella pulchra) – Parker, 1925.
  • Guibe’s Mantella (Mantella nigricans) – Jean Marius René Guibé, 1978.
  • Harald Meier’s Mantella (Mantella haraldmeieri) – Busse, 1981.
  • Green Mantella (Mantella viridis)- Pintak & Wolfgang Böhme, 1988.
  • Yellow Mantella (Mantella crocea) – Pintak & Wolfgang Böhme, 1990.
  • Blue-legged Mantella (Mantella expectata) – Busse & Wolfgang Böhme, 1992.
  • Bernhard’s Mantella (Mantella bernhardi) – Miguel Vences, Frank Glaw, Peyrieras, Wolfgang Böhme & Busse, 1994.
  • Black-eared Mantella (Mantella milotympanum) – Mark Staniszewski, 1996
  • Marojejy Mantella (Mantella manery) – Miguel Vences, Frank Glaw & Wolfgang Böhme, 1999.

 

Mantella belong to the anuran family of Mantellidae, a group which includes a current approximation (more species are yet to be described and researched properly) of 212 species (within 12 different genera) specifically from the island of Madagascar and Mayotte. They are under the following classification:

 

  • Phylum: Chordata
  • Class: Amphibia (Lissamphibia – Modern day Amphibians)
  • Order: Anura
  • Family: Mantellidae
  • Subfamily: Mantellinae
  • Genus: Mantella.

 

Today, distinct species can be generally divided into several different phylogenetical groups which are determined by Morphological traits and also distribution, they are as follows:

 

‘Mantella baroni’ Group

  • Harald Meier’s Mantella (Mantella haraldmeieri),
  • Baron’s Mantella (Mantella baroni)
  • Guibe’s Mantella (Mantella nigricans)
  • Harlequin Mantella (Mantella cowanii)

 

Mantella bernhardi‘ Group

A single species is found within this grouping and is believed to be one of the smallest in size (Snout to Vent). It also has one of the most unique calls out of the entire genus.

  • Bernhard’s Mantella (Mantella bernhardi)

 

Mantella betsileo‘ Group

Some of the species found within the Betsileo Group are widely distributed  however, hard to distinguish morphologically (M.betsileo and M.ebenaui) or in colouration. The most common trait between each of the species within this group is the Horseshoe shape marking on the throat pouch/sac. They are descroibed as being one of the most basal species within the genus and are commonly found along costal regions.

  • Blue-legged Mantella (Mantella expectata),
  • Green Mantella (Mantella viridis),
  • Ebenau’s Mantella (Mantella ebenaui)
  • Brown Leaf Mantella (Mantella betsileo)

 

‘Mantella laevigata’ Group

  • Climbing Bamboo Mantella (Mantella laevigata),
  • Marojejy Mantella (Mantella manery),

 

‘Mantella madagascariensis’ Group

  • Madagascan Mantella (Mantella madagascariensis),
  • Golden Mantella (Mantella aurantiaca),
  • Black-eared Mantella (Mantella milotympanum),
  • Yellow Mantella (Mantella crocea),
  • Beautiful Mantella (Mantella pulchra),

GENERAL DISTRIBUTION RANGE

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Measuring a grand total of 592,800 square kilometres (228,900 sq miles), Madagascar is the fourth largest island on the planet.

The Mantellidae family are Endemic to solely Madagascar and the Mayotte islands of the Indian Ocean, however Mantella will only occur on Madagascar and its slightly offshore Nosys (Small islands). When concentrating upon the Mantella species, you will notice that they actually can be found within a very wide spectrum of different assorted habitat types with even some species such as the Brown Leaf Mantella (Mantella betsileo) reportedly adapting to living amongst rubbish piles where food is plentiful, this of course is not seen in other species.
Obviously, depending on the species the habitat requirements/types vary depending on the where the localities are on the island. In basic description, the island is split in half right down the middle by a spine of mountains, this acts as a barrier for the rains and storms that travel from the Indian Ocean from the east. The eastern side of the island is essentially a mixed variety of swamplands, rainforests and coastal forests whilst the western parts are more desert, arid and drier woodland based environments.

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Fig. Distribution range of the entire Mantella genus with up-to-date records and descriptions. © 2016 – Joshua Ralph – All Rights Reserved.

GENERAL APPEARANCE

The entire genus are definitely represent some of the smallest frogs in the world and range approximately 17mm to 40mm snout to vent, the smallest of them being Bernhard’s Mantella (M.bernhardi) which measures 22mm on average.  In general, the external features they posses are rounded bodies that, depending on the sex and also individuals in question, are stream-line to plump with a slender and angular head, slender forelimbs and stronger, more powerful hind-quarters.
However, when it comes to colouration, most of the sixteen species and their various locality variants are highly diverse which I will cover more later in future edits of this blog entry. The skin though, with colouration and morphology aside, is smooth in appearance to slightly granular with a shine or matt appearance.

Mantella External Physiology
Fig. 5

When looking at the Ventral side of the specimens, a pair of Femoral glands or pads are highly noticable when looking at the posterior of the specimen. This can be either distinctively marked with differently coloured flecking, or have a slightly raised and granular appearance which in Mantella species is one elongated and singular gland. This however in other Mantellinaes are normally separated rather than being continous, prime examples are members of the Mantidactylus genus.

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Fig. 6 Mantella crocea specimen performing ‘Thanatosis’ after being encouraged to do so. © 2012 – Joshua Ralph – All Rights Reserved.

These glands are not always easy to observe in certain Mantella, but with the appropriate lighting, a maginfying glass and a tiny bit of patience they could possibly be seen. There are a few ways to be able to see the venteral side of the each individual which is to encourage the animal into performing the behaviour named ‘Thanatosis‘ or also known as ‘Playing Dead’. This takes time and practice to do this properly and it can go wrong if not performed by someone experienced, however there is another safer way to looking at the venter and that is by placing the specimen in a vial or a clear plastic tub.

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Fig. 7 Brown Leaf Mantella (Mantella betsileo) placed in a tub to determine ventral markings. © 2013 – Joshua Ralph – All Rights Reserved.

In some species such as the Golden Mantella (Mantella aurantiaca), rather than having distinction flecking they have instead a more distinguished colouration of the entire femoral gland, which is mroe reddish to dark orange in colouration. This can be incorrectly described and can cause panic amongst many keepers, as it shares its appearance with the lethal infection commonly known as “Red Leg”, a disease generally caused by the Aeromonas hydrophila a Gram-negative Bacteria. It doesn’t only infect Amphibia but also Fish and even Humans causing Gastroenteritis, which occurs in younger people or persons that have a weaker immune system.
The femoral glands/pads are more noticable in male specimens and more than likely, are present in the sex to be used in rubbing against the female during courtship, possibly to entice the female into laying the spawn.

Mantella External Venter
Fig. 8

Venteral flecking or blotches can be seen in a majority of Mantella species, except in the Golden Mantella (Mantella aurantiaca) and some localities ( that are yet to be determined and await further reasearch) of the Black-eared Mantella (Mantella milotympanum) which have no distinct markings and are basically uniform in appearance. Normally, venteral markings tend to be either white/cream or blueish in colouration and can be quite diverse in shape, size and even with being consistant between individuals of the same species. Some specimens having very few markings (for its species) and another having many, think of this like freckles on human with a slight difference. Examples of different venters between species can be seen in Fig. 6, 7, 8 and 9.

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Fig. 9 Blue-legged Mantella (Mantella expectata) performing ‘Thanatosis’ defensive behaviour. © 2014 – Joshua Ralph – All Rights Reserved.

These markings can also extend as far as forming a distinct pattern along  the edge of the throat pouch, this is normally is the shape of a ‘Horseshoe’ or even in certin species a more ‘Trident’ form (even this can be inconsistant and broken into several markings). Examples of different throat markings can be seen below in Fig. 10.

Throat Pouch
Fig. 10

TOXICITY OF MALAGASY POISON FROGS

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Fig.11 Golden Mantella (Mantella aurantiaca) showing off a dramatic colouration of dark orange. © 2015 – Joshua Ralph – All Rights Reserved.

Extensive research has shown that all species of Mantella, to some degree are in fact toxic with pharmacologically active alkaloidal secretions, known as “Lipophilic alkaloids”. Obviously a product of their toxicity is their aposematically coloured appearance, that is designed to act as a frontline of defence warning, to ward off predators especially with species such as the Golden Mantella (Mantella aurantiaca) as seen in Fig. 11.

This Page is subject to change, regarding more information to be placed upon it and it to be more extensive.

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