The scorpions of the urban habitat of Rome (Italy)

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A review of the scorpions (three species of the genus Euscorpius, family Chactidae) found in the urban habitat of. Rome, Central Italy, togetherwith an analysis of ...
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Urban Ecosystems, 1998, 2, 163-170

© 1998 K1uwer Academic Publishers "

The scorpions of the urban habitat of Rome (Italy)] PIERANGELO CRUCITTh, MARCELLO MALORI and

orovANNI ROTELLA

Societa Romana di Scienze Naturali, SRSN, Rome via Fratelli Maristi, 431-00137 Rome, Italy

A review of the scorpions (three species of the genus Euscorpius, family Chactidae) found in the urban habitat of Rome, CentralItaly, togetherwith an analysis of the factors which affecttheir distributionand abundance in the town, is pointed out. It appears that Euscorpius carpathicus, a species commonly found on limestone terrains in Latium, is frequent, though not particularly abundant, in the urban area of the city especially along the course of the Tiber River. It appears that Euscorpius flavicaudis, a species commonlyfound on volcanic terrains in Latium and the most common terrains in and around the area of Rome, is the most common species in both the urban and suburban areas of the city. It appears that Euscorpius italicus, a species common in north and northeasternLatium, is represented, in the sample of the scorpionsof the city,by a single, possibly aberrant, specimen. Keywords: scorpions; Rome; distribution; ecology

Introduction Latium, in which the area of Rome is included, one of the most extensive regions of Italy that covers an area of 17203 square km, is very heterogeneous for its climatological, geomorphic and vegetational characteristics. The urban area of Rome (41.59 N 12.27 E) is represented by the territory of the town restricted by the motorway ring of the Grande Raccordo Anulare (GRA) which circumscribes a surface of 360 square km, approximately one-fourth of the municipality, 1507 square km (Zapparoli, 1997) (Fig. 1). Approximately one-half of the territory circumscribed by the GRA is filled with buildings, while the other half has ruins, historical villas, archeological sites, meadows, grasslands and suburban unculti­ vated grounds. Twenty square km are filled with the high-water bed of the rivers Tiber and Aniene. The altitude of most areas is between 50 and 100 m; Mount Mario, the highest elevation, is 139 m high (Zapparoli, 1997). The coast of the Tyrrhenian Sea is 25-30 km due west of downtown. The climate of Rome does not sim­ ply reflect the middle and lower mesomediterranean thermotype which characterizes the central lowland areas of Latium (Blasi, 1994). A survey of the air temperature at five different weather stations, located in the center, NW, NE, SW and SE, pointed out by five Bagnouls-Gaussen diagrams, led to the following conclusions: (1) the difference in temperature maximums and minimums for both January and July for the southwest most station (nearest to the Tyrrhenian Sea: Roma Fiumicino, 2 m a.s.l.) shows the least difference between winter and summer, smallest temperature variation between extremes, and the smallest differences between maximum and minimum temperature, due to the moderating effect of the Tyrrhenian Sea; (2) the SW station shows the highest maximum winter (January) temperature (12.7°C), and the smallest difference in average extremes, as expected;

t SRSN project "Bioecological researches

on the Scorpions of the Mediterranean Basin".

* To whom correspondence should be addressed.

164

Crucitti et al.

Ty.rrhenLan Sea rJmi.ono!. itaLy.

Figure 1. Latium (Lazio), region of Central Italy, the area of the municipality of Rome circumscribed by the Grande Raccordo Anulare (GRA).

(3) due to the "heat island" effect, the Central (urban) station (Roma Monte Mario, 139 m a.s.l.) shows the highest maximum temperature and the greatest maximum/minimum range in July (30.5-16.6°C, difference 13.9°C); (4) the NE station for July (Settecamini, 48 m a.s.l.) shows the lowest temperature maximum (21.8°C) and the smallest variation between maximum/minimum temperature (5.3°C), which would be expected for the SW station if it reflects the moderating effect of the Tyrrhenian Sea; (5) the lowest winter temperature and the prolonged period of summer dryness (darkened areas between the line of temperature and the line of precipitation) are shown both in the diagram of the NW station (Giustiniana, 150 m a.s.l.) and in the diagram of the SE station (Roma Ciampino 137 m a.s.l.). Yearly precipitation is 765 mm on average; snowy precipitation is a very rare phenomenon, averaging 4/1000 days (Palmieri and Siani, 1995). The surface geology of the Rome area is dominated by volcanic rock originating from Pleistocene age, explosive pyroclastics eruptions and a1calino-potassic magmatic flows from the Alban Hills to the southeast and Sabatini Mountains to the northwest. This volcanic mantle is cut by the courses of the Tiber and Aniene rivers which contain Pleistocenic fluvial deposits, ("drift complex"), Holocenic alluvial deposits, and in areas expose Pliocenic marine clays ("marine clay complex") deposited by the Tyrrhenian Sea. This natural surface has been variously modified by human activity and construction (Corazza and Lombardi, 1995; Funiciello et ai., 1995). The natural vegetation is represented by strips of persistent meadows of the suburban areas, trampled down environments, shrubs, ruderal or nitrophilous vegetation, fragments of deciduous and evergreen woods (Pignatti, 1995) (Fig. 2). A recent census has pointed out the presence of about 1300 indigeneous species of plants inside the GRA, more than one fifth of the Italian flora (Celesti Grapow, 1995). In the last 150 years, in the same area, 5151 species of insects

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166 (26 orders) have been collected, an enormous number if compared with the overall entomofauna of Italy, nearly 37,000 species (Vigna Taglianti et al., 1992). Studies on the distribution and abundance of scorpions in urban ecosystems have been largely neglected in recent times as, more generally, firmly stated by G. A. Polis "Ecology is the least-known aspect of scorpion biology" (Polis, 1990). In the Mediterranean Basin, five different families of scorpions occur: they include many oligotypic (2-5 species) genera, especially concentrated in the Eastern Mediterranean area, e.g., the Southern Anatolia and the Palestine (Levy and Amitai, 1980; Kinzelbach, 1984; Sissom, 1990; Vachon, 1966). The Mediterranean genus Euscorpius is a group of 5-6 species, small and black scorpions, scarcely toxic and often abundant in urban ecosystems. Three species occur in Central Italy, the urban habitat of Florence and Rome included (Crucitti, 1993): their presence in the Eternal City and its surroundings has been known for nearly one century (Masi, 1912; Cavanna, 1917). Materials and methods

From the beginning of the 1970s, scorpions have been collected in Latium, Central Italy. Approximately 1000 specimens from over 120 collecting sites, uniformly distributed in the territory of the region were examined by the authors. Scorpions have been collected using pitfall traps or searching for them on the ground, generally under stones or in dry-stone walls, or in human buildings and ruins. During the period 1993-1998, at the same time of the development of the Societa Romana di Scienze Naturali (SRSN) project "Bioecological researches on the Scorpions of the Mediterranean Basin", scorpions have been actively searched for in the urban area of Rome. Specimens have been obtained in the following two ways: • people living in the town have been informed how to collect specimens in houses, cellars, schools, wrestling-schools and garages (many specimens of Euscorpius carpathicus, few specimens of Euscor­ pius flavicaudis and one specimen of Euscorpius italicus): local people also provide useful information about the collecting sites (microhabitat characteristics); • the authors and 5-6 collaborators directly collect specimens in buildings or dry-stone walls or by picking up rocks, and other surface material, generally early in the morning in 20 field trips, one day long, during spring and summer seasons (few specimens of Euscorpius carpathicus and most specimens of Euscorpius flavicaudis). For species determination, trichobothrial numbers and patterns, particularly the V serie of the chela manus, one of the most useful external characters currently used in scorpion systematics, have been utilized (Bonacina, 1982; Vachon, 1983; Bonacina and Rivellini, 1986; Lacroix, 1990, 1991a, 1991b). One hundred and three collected specimens of three species are stored in the zoological collection of the SRSN, preserved in ethanol 75°. Results

Twenty-seven Euscorpius carpathicus (Linnaeus, 1767) were collected from 26 sites in the urban centre of the city. At 25 of the 26 sites, only one specimen was collected; at one site, two specimens were col­ lected. Many specimens were found dead in bad conditions of preservation. In consideration of the size, 30-37 mm, at least 12 specimens from as many sites, may be considered adults. The typology of 20 collecting sites may be summarized as follows: understairs and cellars (7); ground floors of buildings, from courtyards and gardens (3) to garages, wrestling-schools and halls (7); top floors of buildings, in the bathroom or in the kitchen (3). Brick buildings are the type of construction widely distributed in the urban centre.

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