17 



the energy balance which can be achieved. Hie more a bat specializes on limited plant 

 food species, the more its body size will be restricted by comparatively expensive 

 approaches to single flowers. 



Body shape 



Wing aspect ratio; phalanges 



As Ü1 otlier flying vertebrates, the geometry of wing surface related to body weight gives 

 some insight into flight conditions and flight demands of bats, respectively (Smith & 

 Starrett 1979). Thus, relative length of the wing bones participating in flight activity will 

 be determined by aerophysical demands rather than by systematic relationship - large or 

 stocky species have longer 2. phalanges in their 3rd digit. So, differentiation 

 corresponding to relative length of the phalanges in digit III gives evidence of wing shape: 

 the longer the metacarpals, the narrower tlie wing (in fast, tenacious flyers). On the other 

 hand, bats with comparatively stout metacarpals have broader wings (slow, astute flyers, 

 fohage gleaners). 



Early as 1943, Sanborn classified the Glossophaginae into two groups, referring to relative 

 length of metacarpals and phalanges: 



1) First phalanx III longer than 1/3 of metacarpal length III and second phalanx of 3rd 

 finger shorter than 1,5 times the length of first phalanx III: Glossophaga, Lichonycteris, 

 Scleronycteris, Choeroniscus, Hylonycteris, Choeronycteris, Platalina 



2) First phalanx III shorter than 1/3 of metacarpal length Etl and 



a) Second phalanx III shorter than 1,5 times the length of first phalanx III: Lonchophylla 

 and Leptonycteris (meanmg the smaller species witliin each genus), Monophylliis 



b) Second phalanx III longer than 1,5 times the length of first phalanx III: Lionycteris, 

 Anoura, Lonchophylla and Leptonycteris (meaning the large species within each genus). 

 All these results correspond to what we currently know on bat ecology. The genera 

 mentioned first with comparatively short metacarpals usually represent higlily specialized 

 nectar feeders requiring astuteness rather than velocity when patrolling among the 

 blossoms. Though Glossophaga feeds a good deal on insects, these bats presumably 

 capture them on the substrate, not in the air. In case of Leptonycteris, predominantly a 

 hovering nectar feeder, the unusual long-winged profile may not be explained by its 

 feeding ecology alone. Here, the "wing geometry of fast and long-range flight" may have 

 been of evolutionary significance for seasonal migrations (Sahley et al. 1995). Anoura 

 reportedly takes a large proportion of msects in their diet (Gardner 1977); it is, however, 

 questionable whether the relativly elongated wings could be explained as a device for 

 capturing insects in flight (obviously, the morphology of the uropatagial region seems to 

 oppose this opinion, see below) and requires further observation. 



Uropatagium, tail 



The degree of tail membrane development and the presence or absence of a bony tail may 

 be interpreted as an ecological adaptation leading to selective advantages both in foraging 

 and roosting behaviour. Within the primarily insectivorous microchiroptera, a well 

 developed uropatagium witli a long bony tail and long cartilaginous calcars is regarded as 

 a plesiomorph condition. Within the Phyllostomatidae there are numerous variations, 

 including a lacking tail, calcar or uropatagium (Stiirnira, Anoura), various intermediate 

 stages and extreme conditions as a short uropatagium combined with a long, projecting 



