Geology Reference
In-Depth Information
major entomological survey was carried out on the
Uluguru Mountains by Belgian teams of entomo-
logists in 1957 (Basilewsky
&
Leleup, 1960) and
again in 1971 (Berger, Leleup
&
Debecker,
1975). Since 1974, the Zoological Museum in
Copenhagen, Denmark, has carried out entomolo-
gical surveys in the Usambara Mountains
(1974, 1975, 1976, 1977 and 1979), Uluguru
Mountains (1981, 1982 and 1984), Mount
Rungwe (1980), Uzungwa Mountains (1981,
1982 and 1984) and Mount Kanga (1984)
(Scharff, l 990c).
Before 1970, only three species of linyphiids
were known from the Easten Arc, Neriene
kibonotensis (Tullgren, 1910), Ceratinopsis bnoiti
(Holm, 1968) and Mirolinphia sterilis (Pavesi,
1883), all from the Ulugurus and all collected by
the Belgian entomological expediion of 1957.
The linyphiids from this material were described
and ideniied by Holm (1968) and van
Helsdingen (1969, 1970). Since 1986, another 58
species have been described and recorded from
the Easten Arc mountains Jocque
&
(Scharff,
1986; Scharff, l 990b).
Ne riene kibonotnsis, Metalpyphantes
perexigu us, Meioneta habra, Microlinyphia
sterilis, Lpthyphantes extensus,
Metalpphantes lavator, Busellia setera.
2.
Widespread species also found outside
Africa:
1 species. Erigo ne prominens
(Africa, Oman, Japan and New Zealand).
3.
African species with disjunct
disribuion:
3 species. (a)
Wide
disjuncions (East and West Africa):
Busellia setifera, Proeauna humicola.
b)
Close disjuncions (within East Africa):
Araeoncus viaoianyanzae, Metalepyphantes
ovatus.
If the linyphiid fauna of the Easten Arc moun-
tains is compared with that of the nearby moun-
tain areas in the norh and south, and the widely
distributed species menioned above (1 and 2) are
excluded, only
w..
species .raeoncus vic-
toianyanzae
and
Mepphantes ovatus)
are
shared with the northen areas (Kenya) and one
species
(Proelauna humicola)
is shared with areas
in the south (Malawi).
Nine of the 19 genera recorded from the
Easten Arc mountains are widespread genera
that are also well known from the Palaearcic
Region, some even from the Nearcic Region.
Some of the East African species described in this
group of genera are taxonomically very closely
related to Palaearcic species (Holm, 1962; van
Helsdingen, 1969). Thus, 14 of the 16 East Afri-
can species of Wa ckenaeia belong to the peculiar
looking species group (subgenus) Tigellinus
Simon, 1884 (sensu Wunderlich, 1972). Species
belonging to this group of spiders have a dorsal
lobe on the carapace carrying the posterior
median eyes. The shape of the lobe, combined
with the posiion of the eyes and spines, makes it
look very much like the head of a dog with
whiskers (Scharff, l 990b, figs 214 and 223). The
African species form a clearly defined group of
species most closely related to the European
Wa ckenaeria fu rcillata
(Menge, 1869).
Wa lck-
enaeria fu rcillata
is widely disributed in Europe,
but it is the only known Palaearcic representaive
of the species group Tigellinus (Holm, 1984).
Diversiy and disribuions
The mountain linyphiid fauna of Tanzania is
without doubt more diverse than the 97 species
presently reported. Of these, 61 species are
known from the Easten Arc mountains and no
fewer than 50 of these are endemic (82%).
Several other Tanzanian mountains have not yet
been invesigated and some have been only very
supericially eplored. While addiional collecing
in these areas will probably reveal many new spe-
cies, I believe that those areas invesigated in the
Uluguru and Uzungwa mountains have been so
well collected that the majority of the linyphiid
species from these areas have been found (see
discussion).
ll
Easten Arc species are listed in
Table 7.1.
Only 11 species (18%) have a distribuion that
also covers areas outside the Easten Arc. They
can be divided as follows.
1.
Widespread African species:
7 species.
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