Morphometric pattern and biometry of adult Trichoptera (Italian species)

Abstract

Morphometric characters of 961 adult caddisflies, belonging to 327 taxa of the Italian Trichopteran fauna were observed and measured. Sexual dimorphism is reflected in the smaller mean size of males, with mean differences in body length of 12.57%. For the order Trichoptera, regressions of the relationships among body dimensions have been used to estimate the value of exponent b and coefficient a of the allometric function y = a * x b , a power function that describes these relationships very well. The lengths (forewing, head-wing, metafemur, and head) versus body length relationships displayed a high degree of isometry among species, with head-wing and forewing having the highest correlation values (especially in males). The results show that most of the variance depends on isometric size variation and not on allometric shape variation among the different species. For adult caddisflies, this demonstrates constancy of the morphological model in the Italian Trichoptera.

The wing morphology of limnephilid caddisflies in relation to their habitat preferences

“…Kovats (1990) reported a very strong linear relationship between forewing length and forewing area (R² ! These relationships confirmed our hypothesis that flight morphological parameters are strongly correlated with one another and justified the common use of forewing length for the determination of the size of a species in the order Trichoptera (Malicky, 2004;Goretti et al, 2005). Using a much higher number of replications (N = 15), we tested individuals of 26 different species belonging to 13 genera of Limnephili-dae and compared the arithmetic means of the measured flight parameters.…”

“…Because we used preserved material for this study, the primary focus was on morphological parameters and indices, such as forewing length, wing area, relative wing length, male-to-female wing ratio and aspect ratios. 0.97) for five North American Hydropsychidae species, and Goretti et al (2005) found a very strong linear relationship between forewing length and body length (R² = 0.96; ln-transformed) for 961 individuals belonging to 327 Italian caddisfly taxa. 0.97) for five North American Hydropsychidae species, and Goretti et al (2005) found a very strong linear relationship between forewing length and body length (R² = 0.96; ln-transformed) for 961 individuals belonging to 327 Italian caddisfly taxa.…”

“…Aspect ratio is a measure of the shape of the wings and is interpreted as a measure of aerodynamic efficiency (Lindhe Norberg, 2002). Goretti, Ceccagnoli & Di Giovanni (2005) demonstrated strong linear relationships between different morphological features within species and species groups. Therefore, different flight morphologies have evolved (Wooton, 1992).…”

“…Long, narrow wings result in high aspect ratios and allow a shallower gliding angle and are therefore suitable for energy-efficient dispersal flight. Goretti, Ceccagnoli & Di Giovanni (2005) demonstrated strong linear relationships between different morphological features within species and species groups. However, empirical evidence linking morphology, dispersal ability and distribution in aquatic insects is rare, with the exception of some studies on wing morphology in water striders, stoneflies, mayflies (Veps€ al€ ainen, 1978;Corkum, 1987;Malmqvist, 2000) and caddisflies (Gullefors & Petersson, 1993;Kovats et al, 1996;Hoffsten, 2004).…”

“…It is the dominant group in much of the Northern Hemisphere at higher latitudes and elevations, and it is arguably the most ecologically diverse caddisfly family, as larvae occupy a full range of habitats, ranging from lakes to streams and marshes (Holzenthal et al, 2007). First, the wing morphological features characterising dispersal ability are strongly correlated with each other; we base this hypothesis on the results of Goretti et al (2005), who measured Italian Trichoptera taxa and found a high degree of isometry among species. First, the wing morphological features characterising dispersal ability are strongly correlated with each other; we base this hypothesis on the results of Goretti et al (2005), who measured Italian Trichoptera taxa and found a high degree of isometry among species.…”