Ceratina of Eastern Canada 



JESO Volume 139, 2008 



MORPHOLOGICAL AND DNA SEQUENCE DELINEATION OF 

 TWO PROBLEMATIC SPECIES OF CERATINA (HYMENOPTERA: 

 APIDAE) FROM EASTERN CANADA 



S. M. REHAN 1 , M. H. RICHARDS 

 Department of Biological Sciences, Brock University 

 St. Catharines, Ontario, Canada, L2S 3A1 

 email: sandra.rehan@gmail.com 



Abstract J. ent. Soc. Out. 139: 59-67 



Ceratina are small, twig-nesting carpenter bees of cosmopolitan distribution. 

 In Eastern Canada, C. calcarata and C dupla live in sympatry, and females 

 are so similar morphologically that many previous species lists combined 

 both taxa into one category. The problem is that the description of the 

 traditional morphological character used to distinguish between them is 

 easily misinterpreted, placing emphasis on puncture abundance rather than 

 distribution. In this paper we propose a clearer description of this character 

 and provide confirmation using scanning electron microscopy to confirm that 

 puncture placement takes precedence over abundance. We tested the feasibility 

 of the new character for distinguishing between these two species, by testing 

 it on non-entomologists, who used it with 87% accuracy. Moreover, DNA 

 sequencing of the cytochrome oxidase subunit 1 gene for the same specimens 

 revealed 1.29% sequence divergence between the two morphs, providing 

 additional support that C. calcarata and C. dupla are indeed distinct species 

 that can be distinguished morphologically. 



Published November 2008 



Introduction 



Ceratina are small, often abundant, carpenter bees that nest in pithy cores of dead 

 broken stems and twigs (Michener 1985). Although they are found across the globe, they 

 have rarely been studied in detail, and much remains unknown about their basic biology and 

 behaviour (Michener 1979). The genus comprises 19 subgenera, of which three are found 

 in North America (Michener 2000). In eastern Canada, from Ontario to the Maritimes, only 

 three species are found, all members of the subgenus Zadontomerus: Ceratina calcarata 

 Robertson, C dupla Say, and C. strenua Smith (Daly 1973). These three species are also 

 found throughout the eastern United States (Daly 1973). Although all three species often 

 occur in sympatry in more southerly parts of their range, C. strenua is rarely found in 

 Canada and southern Ontario is likely the northern edge of its range. However, in most of 



1 Author to whom all correspondence should be addressed. 



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