PhD Arthur Decae 2010 - Ghent Ecology - Universiteit Gent

(Wunderlich 2004). The findings of U. algerianus in the southwestern Algerian Sahara (Fig.7)
might indicate the possible existence of Ummidia in sub-Saharan North Africa, but no data are
available. The western Mediterranean Ummidia diversity (four described species) probably
relates to local speciation in the western Neoeuropean Archipelago. This hypothesis would
gain supported if indications that the Ummidia populations of the Spanish Andalusia and
Valencia Regions differ at the species level could be confirmed.
Cteniza & Cyrtocarenum
The genus Cteniza has a very narrow distribution in the northwestern Tyrrhenian region only
(Fig. 8). Taxonomically Cteniza is placed in the subfamily Ctenizinae together with its
putative sister-genus Cyrtocarenum that occurs in the Aegean region only (Fig. 9). It is very
difficult, on basis of present knowledge, to find the closest relatives of these two
Mediterranean genera. The homology of the family Ctenizidae has never been established
(Raven 1985, Goloboff 1993) and a revision of Raven’s Domiothelina (Actinopidae +
Ctenizidae + Idiopidae + Migidae) is likely to reveal new relationships. On arguments of
biogeography the Ctenizidae seem to be divided in southern and northern taxa. The South
African ctenizid genus Stasimopus might be more closely related to the Gondwana families
(Actinopidae, Migidae, Idiopidae). The closest relative of the Mediterranean Ctenizidae might
be found either in California (Bothriocyrtum or Hebestatis) or in the eastern USA and eastern
Asia (Cyclocosmia). All Ctenizidae appear to be concentrated in relic populations and both
Cteniza and Cyrtocarenum confirm this observation. The known diversity in Cteniza and
Cyrtocarenum is low (2 species each), but more species might await discovery. Whatever
their origin and relationships both genera contribute to the Mediterranean biodiversity as
inhabitants of the Neoeuropean Archipelago and as such seem to support the thesis that it is
particularly this geological region that has contributed to the Mediterranean mygalomorph
diversity.
Ischnocolus & Chaetopelma
The genera Ischnocolus and Chaetopelma are the members of the family Theraphosidae in the
Mediterranean Region. The family Theraphosidae with 935 recorded species (approx. 35% of
all mygalomorph spiders) has the highest species diversity of all mygalomorpf spider families.
This might partly be due to the fact that all the very large and spectacular bird-spiders are
members of this family, and partly because some Theraphosidae live in more exposed
situations than most other mygalomorph spiders. Notwithstanding their large size and
complex morphology the taxonomy of Theraphosidae is particularly complex and unresolved.
The two Mediterranean genera are generally placed in the subfamily Ischnocolinae. In
Raven’s 1985 revision of Mygalomorphae all member genera of this subfamily are regarded
as Theraphosidae incertae sedis. It is therefore difficult to indicate the close relatives of
Ischnocolus and Chaetopelma living outside the Mediterranean. What is clear however is that
both genera have African affinities and are probably of African (Afro-Arabian for
Chaetopelma) origin. A conspicuous difference between the two genera is their species
diversity. A recent revision of Chaetopelma (Guandanucci & Galton 2008) shows that the
species diversity in this genus is low (three or four species) and the distribution range,
extending all over the Middle East and as far south as the Sudan, is comparatively large.
Chaetopelma is an inhabitant of the southeastern Mediterranean (Fig. 10) where the passive
Afro-Arabian continental front has not been fragmented over geological time. Recently
Chaetopelma has also been reported from the northeastern Mediterranean and Crete, maybe as
a result of man aided introductions. Ischnocolus inhabits the southwestern Mediterranean
(Fig. 11), an area that has seen extensive fragmentation and island forming throughout the
Tertiary period and this might explain the higher species diversity in Ischocolus (Table 1).