Page 45 - Lo Cascio_2015

Worldwide checklist of the island mutillid wasps (Hymenoptera Mutillidae) 573

archipelagoes (Fig. 13) suggests that speciation
processes may be largely influenced by geograph-
ical factors, such the distance from mainland. SIEs
have usually low values both in the continental
islands and in those placed in closed basins (e.g.
Sardinia and Cyprus in the Mediterranean). Despite
the remarkable number of distinctive genera occur-
ring on Sri Lanka, 40% of the species is indeed
distributed also in the mainland. Furthermore, SIEs
are absent from many Lesser Sundas (Bali, Flores,
Lombok and smaller islands), in the larger Japan-
ese islands such as Honshū, Hokkaidō and Kyūshū,
in most of the W Palearctic and in all the Neartic,
which were part of continental landmasses until re-
cent time (Last Glacial Maximum). However, con-
Figure 13. The relationship between isolation index (see
sidering separately each island from its insular Table 1) and percentage of endemism for some islands or
group, not always at an oceanic origin corresponds archipelagoes. Numbers are as follows: 1) Sardinia; 2) Si-
a high level of endemism: for instance, among the cily; 3) Great Britain; 4) Canary; 5) Madagascar; 6) Borneo;
Nansei only Yakushima hosts SIEs, with a value 7) Hainan; 8) Java; 9) Sri Lanka; 10) Sulawesi; 11) Sumatra;
12) Philippines; 13) Taiwan; 14) Japanese; 15) Nansei; 16)
just equal to 14%.
Sakhalin; 17) Grande Terre; 18) Espiritu Santo; 19) N Ma-
When considering the endemics with an intra- luku; 20) New Guinea; 21) Solomons; 22) Tasmania; 23)
island/archipelago distribution range, the higher Vancouver; 24) Cuba; 25) Hispaniola; 26) Galápagos; 27)
percentages are found for those most isolated and Jamaica.
inhabited by few species (e.g. Galápagos and
Solomons) (Fig. 14). Fairly high percentages also
occur for the islands of Gulf of Guinea, Canary and
Lesser Antilles (excluding Trinidad), while both on
Japanese and Nansei the endemics are <50%.
Despite their geographical closeness, northern
Maluku (which include Ambon, Bacan, Buru,
Gebe, Halmahera, Morotai, Seram, Taliabu and
Ternate) harbor a large number of species than the
southern islands of the same group (Kai, Larat and
Tanahbesar), but also twice of percentage of endem-
ics (see Fig. 14). Southern Maluku derived from
eastern Gondwana margin (northern Australia and
southern New Guinea), while the Halmahera block
(N Maluku) is thought to have originated on the
Pacific plate and moved westward along the New
Guinea margin to its present position (see Heads, Figure 14. Intra-archipelago endemics percentages (dark
grey columns) in comparison to the whole number of occur-
2013 and references therein). The different histor-
ical geography would then to account for the signi- ring species (light grey columns) on selected islands’ groups.
Lesser Antilles are here considered excluding Trinidad.
ficant difference found in the rate of endemism for
these sub-archipelagoes.
logy of these hymenopteran is little known, so even-
Niche shift tual examples of “island rule” (sensu Gillespie &
Roderick, 2002) within mutillid wasps must be
As evidenced by Brothers (1989), records given viewed with caution. Nevertheless, a case of niche
in literature about the hosts of Mutillidae concern a shift from the usual hosts (other Hymenoptera)
very low number of species, and in general the bio- occurring in an insular environment has been