Chapter 1 - Núria BONADA

DISCUSSION
Trichopteran species list
Mediterranean climate areas have been considered by several authors as regions that shelter
high diversity (e.g., Raven 1973; Deacon, 1983), comparing with other more temperate faunas.
Reasons for that may be related to the climatic features that provide intermediate levels of
disturbance, that according several authors may imply high species richness (e.g., Minshall,
1988; Sousa, 1984). Moreover, besides these climatic features, historical processes have been
very important to explain the high plant and animal richness present in the Mediterranean
basins area (see Bonada et al., Chapter 3). In fact, some caddisfly species have been evolved in
these areas, as those belonging to the Stenophylax group (Malicky, 1987). That is the case of
Mesophylax aspersus that was one of the most abundant and frequent species in sampled
basins because its ability to avoid dried periods by behavioral adaptations (e.g., Bouvet, 1974;
Bournaud, 1971).
However, and according to the known records of the caddisflies in the Iberian Peninsula made
by González et al. (1987), the Mediterranean area is poorer in species than other more
temperate areas in the north and specially the northwest of Spain. This phenomenon has been
related to historical factors but the major number of studies performed in northern areas in the
Iberian Peninsula mades this statement not definitive (González et al., 1987). Although not all
the Mediterranean basins were sampled in the present study and even though not all the
specimens were able to be identified using larvae (e.g., Hydroptila, Stenophylax …), we collected
a total of 91 species. This represents around 27% of the species recorded in the Iberian
Peninsula. The maximum diversity of caddisflies in the sampled area was found in areas with
high-mountain influences (e.g., rivers from Pyrenees, Montseny and Sierra Nevada ranges) or
regions where a mixing of northern and southern species distributions occurs (e.g., in Segura
basin). Besides this, Mediterranean rivers from central and some southeastern areas (e.g., rivers
from Almería) present a depauperate caddisfly fauna (see Bonada et al., Chapter 8) what can be
related to the lack of more extensive studies in the area (González et al., 1987), but specially to
the harshness of the climatic features specially in the arid southern areas where the human
alteration present all along the Mediterranean coast is even higher.
A representation of groups of species according to their distribution areas are presented in
Figure 4. The sampling sites have been divided in three groups, the northern, central and
southern basins. According to the information obtained from literature species have been
grouped as European (including species present in Pyrenees and Iberian Peninsula), Iberian-
North African and endemic species. Overall, most of the recorded caddisflies collected here
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