sented by fewer species than they are in the low-
lands: Liopterini (Ibaliidae), Calosotinae (Eupelmi-
dae), Rhyssinae and Labenini (Ichneumonidae), and
certain Doryctinae, Cenocoelinae, and Helconinae
(Braconidae). A fourth group of Hymenoptera that is
less diverse in cloud forests (and higher altitudes)
than in lowland forests are neotropical-centered
groups, such as Conura (Chalcididae), Podogaster,
and Neotheronia (Ichneumonidae) and diparine
pteromalids, which are also poorly represented in
North America.
Taxa that are more diverse in cloud forests than in lowland
forests. Some groups are more diverse with increas-
ing altitude, for example, Megaspilidae, Procto-
trupidae, two subfamilies of Diapriidae (Ambositrinae
and Belytinae), Platygastridae, Cynipidae, Eucoilini
(Cynipoidea), some Ichneumonidae (Banchinae, Cyl-
loceriinae, Diplazontinae), phygadeuontine Cryptinae,
phaeogenine and platylabine Ichneumoninae, Ortho-
centrinae and Tryphoninae excluding Netelia (Fig.
4.15), and some Braconidae (Aphidiinae and possi-
bly Alysiinae). A few small montane-centered taxa
(e.g., Heloridae, charipine Cynipidae, and Ormyridae)
are absent from the lowlands below 500 m. A few
groups of Hymenoptera are restricted in Costa Rica
to cloud forests, such as Monomachidae, thynnine
Tiphiidae, and acaenitine Ichneumonidae. Montane-
or cloud forest-centered distribution patterns are dif-
ficult to explain, although the former clearly include
many northern (in the case of Ambositrinae, south-
ern) temperate elements that have barely penetrated
tropical habitats. For example, Acaenitinae, Dipla-
zontinae, phygadeuontine Cryptinae, and tryphonine
Tryphoninae are more species rich in North America
than in tropical South America.
In some cases, this distributional pattern occurs
because hymenopteran distribution patterns reflect
the species richness of their hosts. For example, Cynipi-
dae are gall-formers on oaks (Fagaceae: Quercus), and
Ormyridae are parasitoids of the Cynipidae. In Costa
Rica, most species of oaks grow at altitudes above
1200 m, and the single species that occurs in the low-
land dry forests in the northwestern part of the coun-
try (Q. oleoides) is depauperate in cynipids (Hanson
and Gauld 1995).
Not all of these patterns can be explained by dif-
ferential host distribution. For example, Diplazon-
tinae parasitize syrphid fly larvae associated with
Homoptera (aphids, psyllids, and scale insects). Such
syrphid larvae do not appear to be less diverse or
abundant in the lowlands and are attacked by other
parasitoids (Encyrtidae) in these areas. Two other taxa
associated with aphids, Charipini (Cynipoidea) and
Aphidiinae (Braconidae), are also more diverse in
cloud forests than at lower elevations. No data are
available for altitudinal patterns in species richness
of aphids, but these hosts are less diverse in Costa Rica
than in North America.
Many cloud forest hymenopterans are parasitoids
of flies, including some Proctotrupidae, Ambositrinae
and Belytinae (Diapriidae), most Platygastridae,
Eucoilini, Orthocentrinae (Ichneumonidae), and
Alysiinae (Braconidae). Among diapriids, Entomacis,
Idiotypa, Pentapria, and Spilomicrus increase dra-
matically in numbers of species, as do the platygastrid
genera Amblyaspis, Leptacis, Metaclisis, Synopeas,
and Trichacis (L. Masner, pers. comm.). That many
fly parasitoids reach their maximum diversity in
cloud forests suggests that the dipteran hosts of these
parasitoids also reach their maximum diversity there,
but this has yet to be documented.128 Insects and SpidersFigure 4.15. The number of species of Tryphoninae (excluding Netelia) occurring at different
altitudes in Costa Rica.