Seed-feeding beetles of the weevil tribe Mecysolobini (Insecta : Coleoptera : Curculionidae) developing in seeds of trees in the Dipterocarpaceae

Species comprising two monophyletic groups of Alcidodes sensu late (crassus group and dipterocarpi group) feed on fruits of the ecologically and econo mically important tropical timber family Dipterocarpaceae. Fifteen Alcidode s species are newly described from several thousand specimens of seed-feedi ng beetles reared from south-east Asian dipterocarp hosts (Dipterocarpoidae ) and four other species are revised. Morphological keys are provided for i dentifying these 19 taxa. Weevil associations are provided for 70 species o f Dipterocarpaceae in five genera (16 Dipterocarpus spp., four Dryobalanops spp., six Hopea spp., 39 Shorea spp. and five Vatica spp.). These records relate primarily to specimens reared from seeds in Borneo and in Peninsular Malaysia, but all known previous host records are also included (from Indi a, Andaman Islands, Thailand, Laos, Vietnam and the Philippines) and assess ed. These validated and documented host associations refute general asserti ons that (1) seed-eating beetles are host-specific in the tropics and (2) s eed-eating beetles found on dipterocarp hosts are broad generalists across species in several genera of mast-fruiting Dipterocarpaceae. Most Alcidodes species exploit seeds from several dipterocarp species. Some Alcidodes spe cies occur across broad geographic regions with several host species from a dipterocarp genus, other species have been found only on Bornean Hopea or Dipterocarpus species. Others, such as the two previously undescribed speci es feeding on Vatica species, may be restricted to separate sections of the host genus. Within an extensively sampled and diverse interspecific mast-f ruiting dipterocarp community, no Alcidodes species was observed to feed on sympatric species across genera within the Dipterocarpaceae. Additional ho st records and specimens of Alcidodes spp. throughout the range of the Dipt erocarpaceae in south and southeast Asia are required to further define the se clades and the tribe Mecysolobini in general as well as to resolve the c omplex host associations and distributions documented.