Publications - update 3

One of the several lessepsian species colonizing areas of the Mediterranean is Brachidontes pharaonis, a bivalve with the ability to form dense mytilid mats over a range of different mediolittoral substrata. Since its initial observation from the Maltese Islands in the early 1970s, the species has consolidated its presence all over the archipelago. Close examination of the entire length of the Maltese shoreline was conducted to collect quantitative and qualitative data on the mytilid and on dominant accompanying macrofaunal and macrofloral species, in what represents the first comprehensive mapping of an allochthonous species within an island territory. Brachidontes pharaonis was found to have colonized most of the northern and eastern coastal stretches of the island of Malta, preferring limestone substrata in inlets with limited wave exposure and affected by high marine concentrations of hydrocarbons and other pollutants, where it reached individual abundances exceeding 1000 individuals per square metre.

A cluster of Brachidontes pharaonis (Fischer, 1870) from a Globigerina limestone location on the Ta' Xbiex shore. Barnacles, patellids, chitons and coralline algae are also visible.

Reference:

Cilia, D. P. & Deidun, A., 2012. Branching out: mapping the spatial expansion of the lessepsian invader mytilid Brachidontes pharaonis around the Maltese Islands. Marine Biodiversity Records, 5 (e28): 1-8. DOI link

An alien fish in Maltese waters

A research paper regarding the first recorded occurrence of the Pacific fish Oplegnathus fasciatus (Temminck & Schlegel, 1844) in Malta was recently published in the journal Acta Ichthyologica Et Piscatoria.

Oplegnathus fasciatus (Temminck & Schlegel, 1844)
Valletta, Malta

photo by John Attard

More information may be found here, while the work in its entirety may be accessed here.

New paper published

Pseudotachea splendida (Draparnaud, 1801) - Qormi, Malta.

A paper of interest to the readers of this blog has just been published in this month's issue of the journal Triton.

Cilia, D. P., 2010. A note on shells of Pseudotachea splendida (Draparnaud, 1801) in the Maltese Islands (Central Mediterranean). Triton, 22: 33-34.

Abstract: Shells of the western European helicid Pseudotachea splendida (Draparnaud, 1801) are recorded from a plant nursery in Malta.

Variations on a theme, Part IV

The most common invasive plant in the Maltese countryside is the Cape Sorrel (Oxalis pes-caprae L.). The pictures below, taken at Għajn Tuffieħa, show the usual variety of the flower (1), together with another less frequent form exhibiting extra petals (2) resulting from additional sets of chromosomes in the cells' nucleus (polyploidy).

It is known for its sour taste resulting from a reserve of oxalic acid in the plant tissues, which has also resulted in its Maltese vernacular name of Qarsu (=sour).

(1)

(2)

It came, it saw, it conquered

The non-native Otala punctata (Müller, 1774) is a helicid snail which was imported into Malta through a plant nursery in Mosta. The established population was studied in 2008 by Barbara & Schembri, who mapped its range around the nursery responsible for its introduction. This map is copied and pasted beneath; the part highlighted in yellow by Barbara & Schembri shows the range of the species as in 2008. The red shows the plant nursery itself, while the dark grey shows the studied area.

Today, a substantial number of specimens was found further to the north of the yellow area. I have covered the 'newly colonized' area in blue to give an indication as to its extent. Apparently this snail is very well adapted to the kind of anthropogenically disturbed habitat presented in the vicinity, and will continue to colonize new areas and advance as predicted in the 2008 paper. The larger its range becomes, the less anything can be done to exterminate it, which is very bad news for native (and less aggressively competitive) snails.

*The photograph of the Otala punctata specimen above was taken at point 'a'.

Reference:

Barbara N. & Schembri P. J., 2008. The status of Otala punctata (Müller, 1774), a recently established terrestrial gastropod in Malta. Bollettino Malacologico, 44 (5-8): 101-107.

More alien blobs

Almost a mere month after the first record of the jellyfish Cassiopea andromeda from Malta, a new cnidarian species is confirmed as existing in our waters.

This time, far from being anything harmless as in the above-mentioned case, the culprit is the painful stinger Physalia physalis (L., 1758), a hydrozoan (not a true jellyfish) known better as the Portuguese Man-Of-War. The species is more or less frequent in the Atlantic Ocean and only ventures into the Mediterranean occasionally.

The sighting at Ċirkewwa was fortunately recorded on camera by Mr. Adrian Buttigieg, lending more credibility to accounts of sightings off St. Paul's Bay in 2009.

Sluggish cousins

The slug Lehmannia valentiana (Férussac, 1822) is an Iberian peninsular species which has been spread inadvertently as far as Australia, and fairly recently it has also been recorded from Malta (Beckmann, 2003; Mifsud et al., 2003). These animals are imported mostly through plant nurseries, and are so far restricted to damp anthropogenic habitats like flowerbeds and potted plants. The following example is one of a few dozen individuals found beneath humid compost at a garden in Santa Venera. As can be seen, distinguishing features include a symmetrical pair of very dark bands on the dorsal side with a fainter one in the middle, over a light-brown or yellow body colour. It seems that fully adult specimens are highly unusual, probably because of pesticidal and meteorological interference. The population from which this individual came contained slugs of about 20-35mm length (in full extension).

Its close relative Lehmannia melitensis (Lessona & Pollonera, 1882) is, on the other hand, native to Malta and Italian islands. In Malta*, this can be distinguished from L. valentiana by an ash-grey colour, considerably clearer bands and a larger size (up to 55mm). In addition to this, it also seems to prefer more open spaces and minimal human presence. The typical specimen below originates from the countryside surrounding Mdina, where it seems to be relatively commoner than in other areas.

*Sicilian forms of this same species have a yellowish colour.

References:

Beckmann K.H. (2003). Kurze Mitteilungen - Neunachweis von Lehmannia valentiana für die Maltesischen Inseln. Heldia, 5 (1/2): 37-40.

Giusti F., Manganelli G. & Schembri P.J. (1995). The non-marine molluscs of the Maltese Islands. Monografie Museo Regionale di Scienze Naturali, Torino, 15: 1-608.

Mifsud C., Sammut P. & Cachia C. (2003). On some alien terrestrial and freshwater gastropods (Mollusca) from Malta. The Central Mediterranean Naturalist, 4 (1): 35-40.

Welter-Schultes F. (2009). Species summary for Lehmannia melitensis. In AnimalBase Project Team, 2005-2009. AnimalBase - Early zoological literature online, University of Göttingen. Retrieved 14th January 2010 from http://www.animalbase.uni-goettingen.de/zooweb/servlet/AnimalBase/home/species?id=2634

Welter-Schultes F. (2009). Species summary for Lehmannia valentiana. In AnimalBase Project Team, 2005-2009. AnimalBase - Early zoological literature online, University of Göttingen. Retrieved 14th January 2010 from http://www.animalbase.uni-goettingen.de/zooweb/servlet/AnimalBase/home/species?id=2637

Research Paper 2

Cilia, D. P. (2009). On the presence of the alien freshwater gastropod Ferrissia fragilis (Tryon, 1863) (Gastropoda: Planorbidae) in the Maltese Islands (Central Mediterranean). Bollettino Malacologico, 45: 123-127.

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