An appraisal of subspecific classification of Apis mellifera L. in parts of West and Central Africa through landmark-based geometric morphometric analysis of forewings

Abstract

To appraise the subspecific classification of Apis mellifera L. in West and Central Africa, 1663 workers from 175 colonies from 44 localities, were sampled throughout Nigeria and parts of Niger, Cameroon and Chad. The samples were analysed with reference subspecies (A. m. adansonii (N = 12), A. m. jemenitica (N = 14) and A. m. scutellata (N = 12)), using geometric morphometric analysis, based on 19 landmarks on the left forewings of workers. The analysis allowed separating size and shape of the wing. Hierarchical cluster analysis followed by stepwise discriminant analysis (DA) grouped the colonies into two morphoclusters with a cross-validation classification rate of 96.6%. ANOVA revealed a significant difference (p < 0.0005) between the unknown colonies and either of A. m. jemenitica and A. m. scutellata but an insignificant difference (p > 0.05) between them and A. m. adansonii in respect of size. MANOVA revealed a significant difference (p < 0.0005) between the unknown colonies and each of the reference subspecies regarding shape or form (shape + size). All the colonies formed one cluster in a PCA of shape and form, respectively. Based on shape, DA assigned 46.02% and 2.84% of the unknown colonies to A. m. scutellata and A. m. adansonii, respectively, with a posterior probability of ≥95%. However, when shape and size were combined, DA assigned 28.40%, 21.02% and 10.23% of the unknown colonies to A. m. adansonii, A. m. scutellata and A. m. jemenitica, respectively, with a posterior probability of ≥95%. Thus, though this classification is not definitive, it suggests that the unknown colonies are morphologically closer to adansonii and scutellata than jemenitica. However, in order to avoid further confusion in the nomenclature of the honey bees of this region, it is recommended that A. m. adansonii could be retained as their sole subspecific name, pending further studies.

Keywords:

• honey bee
• morphometry
• adansonii
• savanna
• subspecies
• shape
• discrimination
• taxonomy
• systematics

Acknowledgements

We wish to express our sincere gratitude to Ms Beate Springer and PD. Dr. Stefan Fuchs of Institut für Bienenkunde, Oberursel, for their assistance in dissections and provision of reference data, respectively, and to the Institute for providing some of the laboratory facilities used in the study. Similarly, we wish to thank Dr Adam Tofilski of the Department of Pomology and Apiculture, Agricultural University, Kraków, Poland, for his guidance in the acquisition and analysis of GM data and the improvement of the manuscript. Our special thanks go to the numerous beekeepers, honey hunters, public servants, traditional rulers (in particular, His Royal Highness, The Emir of Okuta in Kwara State, Nigeria, Alhaji Idris Abubakar, Shero Betete III) and others for their support during field trips.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data for this article can be accessed https://doi.org/10.1080/00218839.2019.1696009.

Additional information

Funding

The study was partially funded by the Federal Government of Nigeria through TETFund and Abubakar Tafawa Balewa University.