Abstract
Aquatic and semi-aquatic bugs (Heteroptera) represent a remarkable diversity and a resurging interest has been given to documenting at the species level these insects inhabiting Cameroon in Central Africa due to their potential implication in the transmission of the bacterium Mycobacterium ulcerans, the causal agent of Buruli ulcer, an emerging human disease. A survey was carried out over two years in Cameroon. Morphological analyses were done in two steps. A first step consisted in separating the specimens based on broadly shared characters into morphotypes. The specimens were then separated into two independent batches containing each the same representation of each morphotype. One batch (309 specimens) was used by taxonomy experts on aquatic bugs for species level identification and/or to reconcile nymph with their corresponding adult species. The second batch (188 specimens) was used to define species based on the COI DNA sequences (standard sequence used for “DNA barcoding”) and using the Automatic Barcode Gap Discovery (ABGD) method. The first morphological analysis step separated the specimens into 63 different morphotypes (49 adults and 14 nymphs), which were then found to belong to 54 morphological species in the infra-orders Gerromorpha and Nepomorpha based on the species-level morphological identification, and 41–45 putative molecular species according to the gap value retained in the ABGD. Integrating morphology and “DNA barcoding” reconciled all the specimens into 62 aquatic bug species in Cameroon. Generally, we obtained a good congruence between species a priori identified based on morphology from adult morphotypes and molecular putative species. Moreover, molecular identification has allowed the association of 86% of nymphs with adults. This work illustrates the importance of integrative taxonomy.
Highlights
Aquatic and sub-aquatic true bugs (Heteroptera), comprised in the Leptopodomorpha, the Gerromorpha and the Nepomorpha infra-orders, represent a remarkable species diversity of the aquatic biota with 4,656 species from 326 genera and 20 families found worldwide except in Antarctica [1]
After the advanced morphological analysis comparing specimens to the aquatic and sub-aquatic bugs collections preserved in the Museums (MNHN, France; National Museum of Natural History (NMNH), The Netherlands), these morphotypes were dispatched in 54 species belonging to 11 different families (Tables 2 and 3)
Each of ten morphotypes were further separated in two distinct species: Mor13 separated into Macrocoris flavicollis flavicollis and Macrocoris laticollis laticollis, Mor16 separated into Laccotrephes dilatatus and Laccotrephes fabricii, Mor17 separated into Laccotrephes calcaratus and Laccotrephes armatus, Mor18 separated into Laccotrephes latimanus and Laccotrephes sp., Mor21 separated into Anisops (Micranisops) apicalis and Anisops (Micranisops) parvulus, Mor25 separated into Anisops (s. str.) sardeus and Anisops sp., Mor31 separated into Limnogonus (s. str.) cereiventris and Limnogonus (Limnogoïdes) poissoni, Mor33 separated into Neogerris severini and Gerris swakopensis, Mor38 separated into Hydrometra sp.1 and Hydrometra huntchinsoni and Mor39 separated into Hydrometra albolineata and Hydrometra sp.2 (Table 2)
Summary
Aquatic and sub-aquatic true bugs (Heteroptera), comprised in the Leptopodomorpha, the Gerromorpha and the Nepomorpha infra-orders, represent a remarkable species diversity of the aquatic biota with 4,656 species from 326 genera and 20 families found worldwide except in Antarctica [1]. Several surveys of aquatic bugs were carried out in the 1940s in Africa, in West and Central Africa, i.e. the Ivory Coast [2] and Cameroon [3,4,5]. After this period, the aquatic bugs of West Africa were not studied for decades. In order to identify taxa which are difficult to separate only on the basis of their morphology, different authors have proposed the “DNA barcoding” which uses a standard region of the mitochondrial gene Cytochrome Oxidase subunit I (COI) [14,15,16]. Several studies have established that the COI gene is very useful in insect taxonomy including Hemiptera, especially aphids [17,18,19], and true bugs [17]
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