These are species that are stenotopic (i.e., species with small niche breadth) and indicator of only one or two habitat groups.
A stronger decrease is also observed for these species at the 10-group level (differences between alluvial grasslands and pond fringes); it is counterbalanced by a high INDVAL increase for several stenotopic species.
On the other hand, a country having many rare specialized species (endemic and/or stenotopic
species, with a narrow geographical and/or ecological spectrum) may have a high conservation value.
Nowadays this stenotopic
species inhabits most commonly well isolated dunes.
Spiders constitute an abundant, diversified and well-known taxonomic group in salt marshes (Fouillet 1986; Desender & Maelfait 1999), including specialist (stenotopic
) species, the so-called "halophilic species" (Hanggi et al.
For example, Lophopilio palpinalis (Herbst 1799) has been described as "stenotopic
?" (Komposch 1997a) on one hand, and as "moderately eurytopic" and "vertical-ubiquistic" (Kolosvary 1965; Komposch 1999) on the other.