Barbronia weberi (R. Blanchard, 1897) (Hirudinea: Salifidae), an Asian leech species new to Italy

Barbronia weberi (R. Blanchard, 1897), an Asian leech with records of introductions to South and North America, Australia, New Zealand and Europe, was found in two small-size pedemontane streams in North-West Italy (Regione Lombardia) during macroinvertebrate bioassessment sampling. This is the first record of the species in this country, where the family Salifidae is not represented. The species can be distinguished from common native erpobdellids of similar general habitus by the presence of two accessory ventral pores, three pairs of pharyngeal stylets and the presence of minute papillae covering the body. Current distribution and effects of B. weberi on Italian freshwater ecosystems should be determined through further studies.

Leech species belonging to the families Erpobdellidae and Salifidae are typically freshwater predators of invertebrates (i.e. annelids, arthropods and molluscs). Members of the Erpobdellidae common in North America and Europe are characterized by having multiple testisacs per segment. Members of Salifidae common in Africa, Asia, and Australia have few large vesicular testes per segment and possess pharyngeal stylets; a dorsal gastropore and/or post-cephalic eyespots may be present (Sawyer 1986;Nesemann and Neubert 1999).
Barbronia weberi (R. Blanchard, 1897), a species of Salifidae formerly allocated to the family Erpobdellidae (Soós, 1966), has a native range from Afghanistan and Pakistan to Java, Sumatra, Borneo and Southern China. It is the most common leech of the Indian subcontinent (Nesemann and Neubert 1999). This species has been introduced, probably through the aquarium trade to New Zealand (Mason 1976), England (Sawyer 1986), Austria and Germany (Nesemann and Neubert 1999), Brazil (Pamplin and Rocha 2000), United States of America (Rutter and Klemm 2001), and Australia (Govedich et al. 2002). Another species of Barbronia [B. arcana (Richardson, 1970)] was recently recorded in Mexico (Oceguera-Figueroa et al. 2005). According to Fauna Europaea Web Service (2004), B. weberi has never been reported in Italy.
In its native area, the species lives in small running waters as well as in ponds and eutrophic lakes. It is often associated with aquatic vegetation using plants as a substrate and for the attachment of cocoons. Its close association with   common aquarium plants such as Hydrilla verticillata (L. f.) Royle and Elodea spp. has favoured the introduction of this leech into new habitats (Govedich et al. 2003).
Barbronia weberi is clearly distinguished from common autochthonous erpobdellids of similar general habitus (genera Dina and Erpobdella) for the presence of two accessory copulatory pores, one anterior and one posterior to the male and female gonopores (Figure 1). Three pairs of pharyngeal needle-shaped stylets ( Figure 2) were also observed in fixed animals. The species can be distinguished in the field for the presence of minute papillae covering the body, so that the surface takes a rough appearance.
As in other countries, the aquarium trade is the most probable source of introduction of this species. The current distribution of B. weberi in Italian freshwater ecosystems is unknown since this is the first record for Italy. The high reproductive rate and tolerance to a wide range of environmental conditions makes B. weberi a very good colonizer, and once established, it can then be transported to new systems by natural vectors, such as waterfowl, or through connecting waterways (Govedich et al. 2003).
The consequences of the introduction of this new species on aquatic systems is not yet clear. Being a predator with rapid development, B. weberi has the potential to compete with and/or to feed on native invertebrate species (Govedich et al. 2002), but at present no field data are available on these effects.