PhD Arthur Decae 2010 - Ghent Ecology - Universiteit Gent

genera are classified in the subfamily Nemesiinae (Raven 1985) and they represent the
western most taxa of a more or less continuous Palaearctic longitudinal distribution range
running from the Pacific in the East to the Atlantic in the West (see Chapter 5). They are
absent from the northern permafrost affected regions of Eurasia indicating a low dispersal
capacity when compared with Atypus. The Mediterranean diversity at the genus level is fully
restricted to regions that originated in the Neoeuropean Archipelago (Figs. 2-5) and only the
genus Nemesia has one species (N. cellicola Audouin 1826) on the African continental plate.
The general Palaearctic longitudinal diversity pattern of Nemesiinae is continued within the
Mediterranean Region with Raveniola in eastern Anatolia (Fig. 2), Brachythele in
southeastern Europe (Fig. 3) and Iberesia in the western, Atlantic regions (Fig. 4). Only
Nemesia has a much broader Mediterranean distribution running from the Atlantic coast to the
eastern Mediterranean. Nemesia has a very different pattern of diversity in the western and
eastern parts of its distribution range that reflects palaeogeographic configurations in its
present distribution rather than the present geography (Chapter 5). A strong positive effect on
building Nemesia diversity should therefore be attributed to situations of geographical
fragmentation and isolation during the millions of years of existence of the Neoeuropean
Archipelago. The idea that Nemesiidae in Europe have been repeatedly ‘pushed back’ into
small fragmented and isolated refuge populations in a series of Pleistocene glaciations, and
that these ongoing cycles of fragmentation and isolation have lasted sufficiently long for
further diversification and speciation cannot be ruled out however. Thorough species level
revision of all nemesiid genera is needed to clarify these propositions.
Cyrtauchenius
Raven 1985 grouped the genera Cyrtauchenius and Homostola in an all African subfamily
Cyrtaucheniinae, with a disjunct distribution to the North and South of the tropics (Fig. 6
inset). Tropical African cyrtaucheniids are placed in another subfamily, Aporoptychinae,
together with the Australian and American taxa. The Asian genus Anemesia (WSC Platnick
2010) is probably wrongly placed in the Cyrtaucheniidae and should be moved to Nemesiidae
(probably genus Raveniola). The grouping with Homostola of Cyrtauchenius suggests an
African origin of the Mediterranean cyrtaucheniids. From biogeography this seems difficult to
explain and from this perspective the Cyrtaucheniinae are expected to be paraphyletic. On the
other hand however the Mediterranean cyrtaucheniids have clearly southern affinities,
although the comparatively high species diversity seems to be related to a long history of
fragmentation and isolation of populations in the western Neoeuropean Archipelago. A
problem with the interpretation of the currently known distribution of Cyrtaucheniinae is the
complete absence of information from sub-Saharan North Africa and from southwestern
Africa. Information on the mygalomorph fauna of the Sahel region is expected to aid
importantly to the information presented here.
Ummidia
The Mediterranean Ummidia population is revised in Chapter 6. It was found to contain at
least four species all distributed in the Iberian-Maghreb region (Fig. 7). Traditionally
Ummidia is grouped with Conothele in the subfamily Ummidiinae (formerly Pachylomerinae)
with a remarkably wide distribution in the Northern Hemisphere and the Indo-Australian
Region. In the revision presented in Chapter 6 Ummidia and Conothele are placed in
synonymy in which the name Ummidia has priority. Ummidia therefore has an almost
worldwide distribution, mainly although not entirely north of the equator. The East Asian
genus Latouchia probably is the closest living relation of Ummidia (personal observation).
The Mediterranean Ummidia population appears to be a remnant of a much wider European
distribution as is evidenced by the finding of fossil Ummidia specimens in Baltic amber