Resolving taxonomic ambiguity and cryptic speciation of Hypotrigona species through morphometrics and DNA barcoding

Stingless bees are important pollinators of cultivated and wild plants, contributing significantly to biodiversity and food security. Conserving pollinator plant interactions is essential to secure these ecosystems services. The use of morphological features in the identification of stingless bees in the genus Hypotrigona is extremely difficult, due to many similarities among species resulting in taxonomic ambiguity. Here, we apply both traditional morphometrics and DNA barcoding as complementary tools for the identification of three Hypotrigona species from Kenya: Hypotrigona gribodoi, H. ruspolii and H. araujoi. Our results show that morphometrics separates H. gribodoi and H. ruspolii from H. araujoi; however there is an overlap between H. gribodoi and H. ruspolii. On the other hand, DNA barcoding separates the three species. There was lower genetic distance between H. araujoi and H. gribodoi from Kakamega (1.4%) than between H. gribodoi collected from Kakamega and H. gribodoi from Mwingi (4.3%). The high genetic distance or intraspecific distance within H. gribodoi strongly suggests cryptic speciation within this species, and that the H. gribodoi collected from Mwingi is a putative new species. Thus the use of morphometrics and molecular taxonomic approaches (DNA barcoding) provide a convenient, robust and reliable way to identify Hypotrigona species. It also indicates the need for a thorough revision of H. gribodoi species.