244 PROCEEDINGS OF THE NATIONAL MTJSEXJM vol. io9 



due to condensation from the northeast trade winds are features of 

 this zone. The subtropical zone is extensive in the Chiriqui highlands 

 and in the two mountainous spurs of the Andes near the Colombian 

 border. Characteristic plants include Podocarpus, oaks, palms, and 

 many ferns, epiphytes, and lianas. 



The temperate zone (temperate forest) is confined to the summit of 

 the Volcdn de Chiriqui above 8,500 feet elevation. Decrease in 

 moisture and lower temperatures, dropping to below freezing, result 

 in a stunting of the vegetation (pygmy forest) and a heavy overgrowth 

 of moss and lichens. Low ericaceous and myrtaceous shrubs become 

 dominant, among them Dendrophthora spp., Arcytophyllum lavarum, 

 and Maytenus woodsonii. 



Distribution of Culicoides by Life Zones 



We can make only tentative lists of the species of Culicoides char- 

 acteristic of each life zone, principally because so many of the localities 

 are not completely typical of a zone and most of the collections were 

 not made under optimum conditions in each zone. 



We have chosen the localities of Almirante and Alojinga Swamp 

 as fairly typical of the humid tropical rain forest on the Atlantic 

 side, and the localities of Tocumen and Aguadulce as typical of the 

 arid tropical savanna country on the Pacific coast. All four of these 

 localities have the complication of proximity to coastal salt marshes 

 with a representation of salt marsh species. 



The contrast, however, in the relative abundance of the species 

 found in these two types of environment is evident from table 1. 

 From the table it will be seen that when the salt marsh species (see the 

 following paragraph) are excluded, only six species are common 

 throughout the tropical zone: debilipalpis, diabolicus, dicrourus, 

 galindoi, hylas, and leopoldoi. Seven species are abundant in the 

 humid tropics but absent in the arid tropics: dcotylus, castillae, 

 jluvialis, paraensis, propriipennis, pusilloides, and uniradialis. Only 

 one species, insignis, is abundant in the arid tropics cow-pasture 

 country but absent in the Almirante and Mojinga rain forests. Al- 

 mirante has three abundant species — elutus, nigrigenus, and panamen- 

 sis — not found at Mojinga, and Mojinga has only one abundant 

 species, caprilesi, not found at Almirante. Of the rarer species, two — 

 ginesi and pusillus — are found in all four localities, two — jamaicensis 

 and macrostigma — are found in all but Aguadulce, and one — foxi — 

 is found in all but Almirante. Twenty rare species were taken in 

 the humid but not in the arid tropics: antefurcatus , aureus, halsa- 

 pambensis, camposi, carsiomelas, crescentis, daedaloides, gabaldoni, 

 glabrior, lanei, mojingaensis, pachymerus, patulipalpis , pijanoi, pilosus, 

 poikilonotus, spurius, tenuilobus, tetrathyris, and verecundus. Four- 



