Flowers on the volcano

Following yesterday's journey we have now arrived close to the summit of El Teide. The landscape is a vast expanse of bleak volcanic rock, including obsidian, phonolite and trachyte, which form when lava solidifies according to different physico-chemical criteria.

El Teide volcano

Teide's most recent eruption dates back to 1909, and some tremors have been recorded in 2004, indicating a dormant volcano may become active in a few years' time.

El Teide's 1909 eruption, live (photo stolen from here)

In any case, the plants seem quite happy about their choice of habitat. A large number of endemic species characterize Tenerife and many of these species are abundant high above the pine forest. The southern side of the Teide, in the Las Cañadas caldera, is a habitat known as subalpine scrub, dominated by shrubs of the legume Spartocystus supranubius L., together with bushes of the beautiful Pterocephalus lasiospermum Link.

dark green shrubs of Spartocystus supranubius L., with Pterocephalus lasiospermus Link in the foreground

Spartocystus supranubius L. with seed-pods

Pterocephalus lasiospermus Link

flowers of Pterocephalus lasiospermus Link

Amongst these one can also find the very interesting Cheirolophus teydis (C.Sm.) G.López, an endemic plant of Teide that is a very close relation of Malta's national (and also endemic) plant, Cheirolophus crassifolius (Bertoloni). Unfortunately all plants were only on the verge of flowering during this visit. Flowers of C. teydis are pale yellowish.

Cheirolophus teydis (C.Sm.) G.López

Adenocarpus viscosus (Willd.) Webb & Berthel. and several species of Echium are also very characteristic inhabitants of El Teide, characterizing landscapes with their yellow flowers and tall spikes respectively.

Adenocarpus viscosus (Willd.) Webb & Berthel.

Echium sp.

Echium sp. flowers

lycaenid butterfly resting on Echium sp.

Above the clouds of El Teide

The third largest volcano on earth (according to some sources, but not to others - it depends on how you go about measuring volcanoes) is found off West Africa, on Tenerife.

To see the majestic peak of this volcano, El Teide, one must traverse a height of about two kilometres of pine forest, dominated by the endemic Canarian pine Pinus canariensis C.Sm. This pine has developed an extraordinary way of utilizing the water available in the mist enveloping these forests - its leaves are tall and thin, allowing condensation of water droplets on their large surface area. This water trickles down, dropping into the soil and providing roots with much-needed hydration.

Pinus canariensis C.Sm., 2.5km up east El Teide

In some places, violent storms some years back have ripped the trees down, the trunks of which together with the flowing clouds produce an eerie atmosphere reminiscent of any horror film worth its salt:

wind-battered pine forest, c. 2km up east El Teide

After the ascent of about another kilometre one can see the forest spread below and a wide swathe of cloud enveloping it:

About 3km up El Teide, the volcano in the background

Coming up next: some local flora.

Endangered Species Day 2011

On the occasion of Endangered Species Day 2011, I present one of the most characteristic floral endemics of Malta, namely the Maltese Everlasting (Helichrysum melitense). This plant grows on the cliffs of Dwejra (Gozo) and Fungus Rock, and is most probably extinct in the wild from Malta. The remnants of the population are threatened by quarrying (mostly illegal), dumping of construction materials, alien species and habitat deterioration.

Helichrysum melitense (Pignatti), Dwejra - Għawdex, 21.VI.2008

Species spotlight IX

Tudorella melitense (Sowerby, 1847)
Xlendi, Gozo

Tudorella melitense (Sowerby, 1847) is the only snail with an operculum ('door') which is native to the Maltese Islands. Under a 'biological species definition' it may be considered to be a local variety of Tudorella sulcata (Draparnaud, 1805), which also occurs in Sicily; Pfenninger et al. (2010)*, in their work on the DNA of Tudorella, consider it a lineage which is only found in the Maltese Islands.

Għajn Tuffieħa, Malta

The shell is very variable, and may be orange, white or purple, with or without bands.

Għajn Tuffieħa, Malta

*Pfenninger, M., Véla, E., Jesse, R., Arantzazu Elejalde, M., Liberto, F., Magnin, F., Martínez-Ortí, A., 2010. Temporal speciation pattern in the western Mediterranean genus Tudorella P. Fischer, 1885 (Gastropoda, Pomatiidae) supports the Tyrrhenian vicariance hypothesis. Molecular Phylogenetics and Evolution, 54: 427-436.

The rediscovery of Gibbula nivosa

The best known marine snail endemism in the Maltese Islands is certainly Gibbula nivosa Adams, 1851 - in vernacular, this is the Maltese Topshell. This mollusc was previously known in a 'live setting' only from St. Thomas' Bay in Marsaskala, with the ever-increasing scarcity of live individuals leading some authors to speculate on its extinction.

A paper published last November, however, sets the record straight - G. nivosa is alive and kicking (albeit in a critically endangered manner) in two localities around the Maltese Islands. You can read the original abstract here and a synopsis here.

Gibbula nivosa Adams, 1851
on a 1979 stamp

Burst of purple...

... or indigo, lilac, anyway - whatever you want to call it. Cheirolophus crassifolius (Bertoloni) is much better known as Widnet il-Baħar, and it has been designated as the national plant of Malta. It is an endemic species with a troubled taxonomic history and embellishes cliffs with its beautiful blooms during most of summer. A very hardy plant which withstands highly alkaline soil, it has also been used as an ornamental and is frequently seen in roundabouts, public gardens and roads, though it remains very rare in the wild.

To read about the Maltese national tree please click here.

Sinister sphinxes?

Hyles (Rommeliana) sammuti Eitschberger, Danner & Surholt, 1998 -

Buskett 11.XI.2009

This is the larva (caterpillar) of an endemic moth from one of the most aesthetically pleasing families in the Lepidoptera, namely the Sphingidae. Before its description in 1998, Maltese specimens belonging to Hyles sammuti Eitschberger, Danner & Surholt, 1998 were thought to belong to Hyles euphorbiae (L., 1758), a common Mediterranean species, due to similar morphology and habitat.

An adult specimen of H. sammuti may be seen below, this photograph is taken from the excellent Sphingidae of the Western Palearctic website.

The sphingids found on the Maltese islands also count amongst their ranks the infamous Acherontia atropos, (L. 1758) - undoubtedly the most famous lepidopteran amongst cinema buffs worldwide.

More on Pleistocene rodents

Dorothea Bate (1878-1951) was a British explorer and palaeontologist whose main interests were Mediterranean Pleistocene mammals. The first woman scientist to hold a permanent post at the Natural History Museum in London, she discovered and named a number of new species from Crete, Cyprus, Malta and the Balearic Islands.

Two Pleistocene vole species bearing her authorship are known from deposits in Għar Dalam, Malta. Voles, from the rodent family Cricetidae, are very similar to mice, but have a stouter body and a hairy tail. They are nowadays extinct from the Maltese Islands - Gulia (1858; 1890) and some subsequent authors list the vole Arvicola amphibius (L., 1758) as occurring in Malta, but this statement is not supported in any way, either by more recent authors on mammals (Lanfranco, 1969) or by the present writer's observations.

The fossil species named by Dorothea Bate are Terricola melitensis (Bate, 1920) and Terricola pauli (Bate, 1935), both originally placed in the Pitymys genus before it was known that this actually indigenous to North America (Chaline et al., 1999, Kotsakis, 2004). T. melitensis is closely related to Terricola savii (de Sélys-Longchamps, 1838), shown above, which nowadays lives mainly along the Italian peninsula (Brunet-Lecomte & Chaline, 1992; Chaline et al., 1999; Wilson & Reeder, 2005). T. pauli is a large enigmatic species with less obvious affinities, and indeed with a name not encountered much in the literature. The figure of the holotype from Bate's original description is reproduced below.


References:

Bate, D. M. A., 1920. Note on a new vole and other remains from the Ghar Dalam Cavern, Malta. Geological Magazine, 57: 208-211.

Bate, D. M. A., 1935. Two new mammals from the Pleistocene of Malta, with notes on the associated fauna. Proceedings of the Zoological Society of London, 247-264.

Brunet-Lecomte, P. & Chaline, J., 1992. Morphological convergences versus biochemical divergences in the holarctic ground voles: Terricola and Pitymys (Arvicolidae, Rodentia). Neues Jahrbuch für Geologie und Paläontologie, 12: 721-734.

Chaline, J., Brunet-Lecomte, P., Montuire, S., Viriot, L., & Courant, F., 1999. Anatomy of the arvicoline radiation (Rodentia): palaeogeographical, palaeoecological history and evolutionary data. Annales Zoologici Fennici, 36: 239–267.

Gulia, G., 1858. Repertorio di Storia Naturale. Malta, 68 pp.

Gulia, G., 1890. Elenco dei Mammiferi Maltesi. Il Naturalista Maltese, 1 (1): 2-3.

Kotsakis, T., 2004. The Plio-Pleistocene rodents of the Mediterranean islands: origin and evolution. 18th Senckenberg Conference 2004 in Weimar.

Lanfranco, G., 1969. Maltese mammals (Central Mediterranean). Malta: Progress Press, 36 pp.

Wilson, D. E. & Reeder, D. M. [eds], 2005. Mammal Species of the World - A Taxonomic and Geographic Reference [3rd edition]. Johns Hopkins University Press, 142 pp.

Picture of Terricola savii (de Sélys-Longchamps, 1838) from http://www.cogecstre.com/Vertebrati/images/ArvicolaDiSavi.jpg

The giant Maltese dormice

Insular gigantism is an evolutionary process that leads to individuals in a population becoming progressively larger in size than their ancestors.

This process occurs when a population is isolated - for example, on a part of land which detaches from the mainland, beoming an island - and therefore divorced from its previous ecosystem, with all the biotic and abiotic factors which this entails.

In the new environment, the successful species may become free from a considerable number of predators (which may not have enough resources in the new ecosystem, therefore decreasing or becoming extinct) and also competitors (which may not be so successful in the new ecosystem).

In Malta, during the Pleistocene, this process can be seen to have occurred with several species of reptiles and mammals. The extinct giant lizard Lacerta siculimelitensis Böhme & Zammit-Maempel, 1982, still has congeners of smaller size living around the Mediterranean.

Two very interesting 'giants' from Maltese Pleistocene deposits are Leithia melitensis (Adams, 1863) and Leithia cartei (Adams, 1867). Fossils of these two animals were found from Middle Pleistocene deposits in Mnajdra, Mqabba and Wied Inċita, and a jaw from the National Museum of Natural History is pictured above. The genus is from the rodent family Gliridae (the dormice), which does not exist anymore on the islands of Malta. The size of the former was about twice that of the recent species Eliomys quercinus L., 1766, a specimen of which can be seen below. L. cartei was only slightly smaller than L. melitensis - indeed, differentiation based solely on size may give errors (Petruso, 2004).

There is also another genus of Maltese Pleistocene dormice, which consisted of animals smaller than Leithia but still large by 'modern' standards. This genus, Maltamys, consists of two species - Maltamys wiedincitensis Zammit Maempel & de Bruijn, 1982 and Maltamys gollcheri de Bruijn, 1966.

Zammit Maempel & de Bruijn (1982) are of the opinion that both Maltamys and Leithia are derived from Eliomys, due to similarity in anatomical features. However, more recent publications (Petruso, 2002; Petruso, 2004) state that convergent evolution is more probable, meaning that Maltamys and Leithia are more distantly related than previously thought.

Some material of the mentioned four fossil species has since been found in other Mediterranean countries, but all type material comes from Malta.

In a future post we shall look at an evolutionary pattern which is the diametrical opposite of insular gigantism - insular dwarfism.

References:

Böhme, W. & Zammit Maempel, G., 1982. Lacerta siculimelitensis sp. n. (Sauria: Lacertidae), a giant lizard from the Late Pleistocene of Malta. Amphibia-Reptilia, 3 (2-3): 257-268.
Bruijn, H. de, 1966. On the Pleistocene Gliridae (Mammalia, Rodentia) from Malta and Mallorca. Proceedings Koninklijke Nederlandse Akademie van Wetenschappen, B 69 (1): 480-496.
Petruso D., 2002. Il contributo dei micromammiferi alla Stratigrafia e Paleogeografia del Quaternario continentale siciliano. Ph. D. thesis, University of Napoli.
Petruso, D., 2004. New data on Pleistocene endemic Sicilian-Maltese dormice (Gliridae, Mammalia). 18th Senckenberg Conference 2004 in Weimar.
Zammit Maempel, G. & Bruijn, H. de, 1982. The Plio/ Pleistocene Gliridae from the Mediterranean Islands reconsidered. Palaeontology, B 85 (1): 113-128.

Picture of Eliomys quercinus L., 1766 from http://upload.wikimedia.org/wikipedia/commons/d/d5/Eliomys_quercinus02.jpg

New project uploaded

A small website required for a University assignment has been uploaded at the link pasted below:

Maltese Endemic Landsnails

Virtually all photographs included are appearing on the web for the first time.

The website expires this year, so I will upload the content here as soon as that occurs.

Part II: The endemic species of the Maltese Islands

The Maltese Islands, though small, boast a considerable number of endemic species and infraspecific forms, consisting of 23 plants and 55 animals (Schembri, 1994).

Such species, apart from being unique, are biologically important because they show reproductive isolation and speciation at work. The lizard Podarcis filfolensis is perhaps the best known example of this, having evolved into different sub-species on most of the islands of the archipelago. It is the only endemic vertebrate in addition to the shrew Crocidura sicula calypso.

Terrestrial molluscs are a type of animal that evolves relatively quickly, in fact, 14% of the endemic animals are gastropods. Of these, the most interesting are the Hygromiidae and the Clausiliidae, which give clues as regards the isolation of the Maltese Archipelago from the surrounding land. The endemic snails Cernuella caruanae and Trochoidea spratti are relatively widespread, but the rarest gastropod is also an endemic – Lampedusa melitensis is a clausiliid whose population only consists of a few hundred individuals in a restricted ‘rdum’ area at Dingli. A sister species is Lampedusa imitatrix which is found further to the west along the southern coast of Malta. The last endemic clausiliid is Muticaria macrostoma, a taxon previously thought to consist of four different species, but these are anatomically indistinguishable (Giusti et al., 1995). The forms mamotica and scalaris are extremely restricted and therefore vulnerable. The forms macrostoma and oscitans, on the other hand, are frequent and one form prevails according to the geographical location. The southern coast of Malta (including Dingli) harbours the oscitans form.

81% of the endemic animal species are arthropods. These include the beautiful Maltese race of the butterfly Papilio machaon as well as the well-known freshwater crab Potamon fluviatile.
Endemic plants of the Maltese Islands are usually relicts from larger populations in a time when Malta was joined to Europe by a land bridge, for this reason they are called palaeoendemics. These are mostly restricted to rupestral habitats where they have competitively excluded other plants by tolerating harsh conditions such as high salinity. At Dingli, one can witness the species Darniella melitensis, Jasonia bocconei, and Palaeocyanus crassifolius, which is also Malta’s national plant. Cremnophyton lanfrancoi and Allium lojaconoi, a wild garlic that forms part of a cluster of similar species in central Mediterranean islands, are other palaeoendemics. Other endemic plants with more recent evolution are the orchid Anacamptis urvilleana and two species of Limonium, for this reason, they are referred to as neoendemics.

Figures:

Fig. 4. Muticaria macrostoma form macrostoma, from Floriana, Malta

Fig. 5. Muticaria macrostoma form oscitans, from Siġġiewi, Malta

References:

Giusti, F., Manganelli, G. & Schembri, P. J. (1995). The non-marine molluscs of the Maltese Islands. pp. 1-608, Torino.

Schembri, P. J. (1994). Natural heritage. In: Frendo, H. & Friggieri, O. (eds) Malta – Culture and Identity. pp. 105-124; Ministry of Youth and the Arts, Valletta, Malta