Some views from Għar Lapsi, S Malta

Some views of Wied Żnuber, SE Malta

The Maltese national tree

Tetraclinis articulata (Vahl, 1791) is a North African conifer from the Cypress family. It is also the national tree of Malta, and is known locally as 'is-siġra tal-għargħar'. Most specimens encountered in the wild grow on clay slopes and appear to thrive in quite arid habitats. The picture above shows a mature specimen from the Maqluba depression at Qrendi, while below a young individual from Għajn Tuffieħa bay can be seen.

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.

A flawed gem

Luria lurida (Linn., 1758) is a common snail from the family Cypraeidae found in shallow Maltese waters. The specimen above was very timid and did not emerge from its shell fully, even after 30 minutes of waiting on my part. However, the tip of the siphon can be seen on the right hand side, together with a very small part of the mantle covering the shell's edge.

Gastropods happen to be a favourite food of their far more cunning relative, the octopus. An octopus can usually pull other snails right out of their shell, but L. lurida has a narrow aperture and is well-protected in this regard. Besides, it withdraws deeply into its shell, beyond significant reach of the octopus' tentacles. The octopus therefore resorts to drilling a hole in the shell with its tongue, enabling it to secrete enzymes and extract the animal (Wodinsky, 1969).

Such drill-holes are commonly found on beached L. lurida, as can be seen in the photograph below.

Wodinsky, J., 1969. Penetration of the shell and feeding on gastropods by Octopus. American Zoologist, 9 (3): 997-1010.

Bugs!

Few arthropods have appeared on this blog so far, so here's a trio of specimens from that marvellous group known as the Coleoptera:

Ocypus olens (Müller, 1764) Għallis Point 31.X.2009

Oxythyrea funesta (Poda, 1761) - Chadwick Lakes, 25.II.2010

Blaps gigas (Linné, 1767) - Għajn Tuffieħa 23.IX.2009

According to biologist J. B. S. Haldane, if a Creator exists he must have 'an inordinate fondness for beetles'*. Whatever one's religious persuasions (or dissuasions) are, there can hardly be any doubt about the accurate implications of his statement.

*Hutchinson, G. E., 1959. Homage to Santa Rosalia or why are there so many kinds of animals?. American Naturalist, 93: 145-159.

Living snails from Malta - update

Additional photographs of live snails are now available on the Associazione Malacologica Internazionale's website, accessible through my earlier post here.

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