New marine biology papers

1. Mifsud, C. & Cachia, C., 2011. New additions and corrections, with annotations, to the check-list of the marine Mollusca of the Maltese Islands. Triton, 23: 10-18.

This paper is an addendum to the four volumes on marine mollusc records from the Maltese Islands by Cachia, Mifsud & Sammut (1991; 1996; 2001; 2004 - see full references below). In this paper, 99 additional records are mentioned together with a number of corrections of previous records.

Of particular interest is a second species of Paludinella for Malta. This minute snail is rare and lives in marshes, and previously only Paludinella littorina (Delle Chiaje, 1828) was known to occur. Samples from Salina Bay have yielded some individuals of Paludinella sicana (Brugnone, 1876).

A comparison of Paludinella sicana (Brugnone, 1876) and Paludinella littorina (Delle Chiaje, 1828), pictures taken from the Natuurhistorisch Museum Rotterdam collection

Also worthy of mention is the first Central Mediterranean record of the pyramidellid Leucotina eva Thiele, 1925.

2. Deidun, A., Galea Bonavia, F. & Schembri, P. J., 2011. Distribution of Tylos spp. in the Maltese Islands and population dynamics of Tylos europaeus. Journal of Coastal Research, SI 57: 369-372.

Tylos is a genus of woodlice, two species of which - Tylos europaeus Arcangeli, 1938 and Tylos sardous Arcangeli, 1938 - occur on two sandy beaches on island of Gozo. This paper examines their habitat and gives an account of yearly fluctuations in the former's population.

References:

Cachia, C., Mifsud, C. & Sammut, P., 1991. The Marine Shelled Mollusca of the Maltese Islands Part 1: Archaeogastropoda. Malta: Grima Printing & Publishing Industries; 112 pp.

Cachia, C., Mifsud, C. & Sammut, P., 1996. The Marine Mollusca of the Maltese Islands, Part 2: Neotaenioglossa. Netherlands: Backhuys Publishers; 228 pp.

Cachia, C., Mifsud, C. & Sammut, P., 2001. The Marine Mollusca of the Maltese Islands Part 3: Sub-class Prosobranchia to sub-class Pulmonata, order Basommatophora. Netherlands: Backhuys Publishers; 266 pp.
Cachia, C., Mifsud, C. & Sammut, P., 2004. The Marine Mollusca of the Maltese Islands Part 4: Caudofoveata, Solenogastres, Bivalvia, Scaphopoda and Cephalopoda. Netherlands: Backhuys Publishers; 270 pp.

Tideline barnacles

Virtually all rocky seashores in Malta sport millions of these unassuming, pyramidal entities that close or open to feed or reproduce depending on the availability of seawater from tide or waves. They are barnacles mostly belonging to the species Chthamalus stellatus Poli, 1791, though other species of Chthamalus are also present on Maltese shores.

As seen in the photograph above (lower right hand corner and upper centre), dead individuals leave behind calcareous volcano-shaped cavities which may be used as a refuge by other intertidal organisms, such as the amphibious and very interesting snail Melarhaphe neritoides (L., 1758) or even other crustaceans such as amphipods. The photograph was taken at Dwejra, Gozo, during receding tide. On the other hand, the photograph below shows completely dry specimens from Buġibba, waiting for the presence of water to resume any activity.

Back to basics

The isopods are the perfect example of crustaceans that have adapted to life in a terrestrial habitat. However, some of them have opted for a return to the aquatic world, an evolutionary move which finds parallels in other animal groups as diverse as molluscs, reptiles and mammals.

The above picture shows the woodlouse Sphaeroma sp., found beneath a rock in the Salini marshes, a unique ecosystem which features one of the very few brackish water habitats in the Maltese Islands.