Figure 1.
Map of Japan with sampling localities (red circles), created using Google Maps.
Taxonomic lists of the Japanese elaterids have been published by some authors [11–13], and the number of species listed has steadily increased (Table 1). At present, approximately 130 elaterid genera and 770 species have been recorded in Japan (reviewed in Ôhira, 2013 [3]), although the most updated species list was not published with this review. This number of elaterid species in Japan is comparable with that of the whole Nearctic region (965 species) [2] and much larger than that of the British Islands (73 species) [14], which are as large as the Japanese Islands. These numbers highlight the high elaterid biodiversity in Japan. Adult elaterids are relatively common in Japan. They are often collected in various traps during environmental impact statement research and thus appear as significant members in the prefectural lists of wild insects. For example, Elateridae constitutes 5.1% and 4.9% of the beetle species collected in Tochigi [15] and Okayama [16] prefectures, respectively.
Table 1.
Taxonomic coverage of DNA barcoding for Japan and the Japanese regions.
Table 2.
Primers used to amplify and sequence the COI barcode region.
Figure 2.
Maximum p-distance for genus vs. the number of species analyzed.
No strong correlation was found between the two variables (Spearman’s rank correlation coefficient rs = 0.356).
Table 3.
Distribution of sequence divergence (K2P distance/uncorrected p-distance).
Figure 3.
Distributions of the maximum intraspecific p-distances (red) and the nearest neighbor distance for each species (green).
Sequences below 500 bp were eliminated. (A) Japanese click beetles (project name, JEBP). (B) Combination of plots from eight public DNA barcoding datasets (see S4 Fig. for plots of each of the eight datasets) that were used to describe the BIN system by Ratnasingham and Hebert [32]. The public data were acquired from the BOLD system on 7 April 2014.
Table 4.
‘Warning’ species tagged by the BOLD Barcode Gap Analysis with references for their taxonomic problems.
Figure 4.
Comparisons between species and BIN boundaries.
Numbers represent species (inner ring) and BINs (outer ring) categorized into MATCHES (green), MERGES (yellow), SPLITS (orange) or MIXTURES (red). (A) Elaterid dataset of this study. (B) Combination of eight public barcoding datasets for bees, birds, fishes, butterflies and moths (after Ratnasingham and Hebert, 2013 [32]). In a bracket below each chart, the percentage of species that are MATCHES is shown.