Species delimitation can be difficult when the divergence between focal taxa is in the incipient stage of speciation, because conflicting results are expected among different data sets, and the species limits can differ depending on the species concept applied. We studied speciation history and investigated the impact on taxonomic decision-making when using different types of data in a Taiwanese endemic sister-species pair of stag beetles, Lucanus miwai and Lucanus yulaoensis, from sky island habitats. We showed that the two geographical taxa can be diagnosed by male mandibular shape. We found two mitochondrial co1 lineages with pairwise sequence divergence > 3%; however, L. miwai might not be monophyletic. The result of our multispecies coalescent-based species delimitation using five nuclear loci supported the evolutionary independence of the two sister species, but the calculated values of the genealogical divergence index (gdi) corresponded to the ambiguous zone of species delimitation. We also showed that post-divergence gene flow is unlikely. Our study demonstrates challenges in the delineation of incipient species, but shows the importance of understanding the speciation history and adopting integrative approaches to reconcile seemingly conflicting results before making evolutionarily relevant taxonomic decisions.

The fall armyworm (FAW), Spodoptera frugiperda (Smith), is a major pest native to the Americas. A recent invasion of FAWs from Africa eastward to South Asia, the Indochina Peninsula, and mainland China has received much attention due to the considerable economic losses in agriculture. FAWs can rapidly colonise a new area, likely due to the wide range of host plants, good flying capability, and high egg production. Therefore, a convenient, quick, and accurate tool for FAW identification is urgently required to establish a FAW invasion management strategy. In this study, FAW-specific primers were designed to recognise FAWs on the basis of internal transcribed spacer 1 (ITS1). The results revealed the accurate FAW recognition of the three congeneric species and eight common corn lepidopteran pests, especially at their larval stage. Furthermore, species-specific primers have confirmed their efficacy by using 69 FAW specimens from Taiwan, Thailand, and the United States, with a 96% success rate, excluding 3 decayed specimens. By using the simple, reliable, and convenient FAW-specific primers, a pest management programme can be developed not only to reduce sequencing costs and experimental time from 2 days to 4 h, but eradicate the FAW as soon as it enters a new area.

Alpha taxonomy is fundamental for many biological fields. Delineation of the species boundary, however, can be challenging in a species complex, where different species share a similar morphology and diagnostic characters may not be available. In this context, integrative approaches that incorporate molecular and morphological data sets, and account for speciation history can be helpful to alpha taxonomy. Different approaches to species delimitation based on different assumptions are complementary and by integrating the results from multiple approaches we can generate a more reliable and objective taxonomic decision. In this study, we applied three molecular approaches to species delimitation and inferred the demographic history based on an isolation with migration model to test a morphologically based taxonomic hypothesis for the Cylindera pseudocylindriformis complex. We discuss the association between genetic divergence and microhabitat specialisation, and further corroborate that C. subtilis sp. nov. is a valid new species by integrating the results from model-based species delimitation and the genealogical divergence index. We argue that genetic endemism can occur at a small geographic scale, even in a winged insect like tiger beetles. Our results also indicated that there may still be undocumented species diversity of Taiwanese Cylindera remaining to be discovered. ZooBank LSID: urn:lsid:zoobank.org:pub:9DEC1432-365C-4872-8D06-73B95F30624F

Tiger beetles have been recognized primarily based on morphological characters. However, the variations of elytral maculation and coloration sometimes lead to misjudgment in species classification and the overlooking of the existence of cryptic species. Recently, specimens of two endemic species of Taiwanese Cylindera, C. sauteri and C. pseudocylindriformis, exhibit morphologically recognizable forms, indicating that some undescribed species may exist. To clarify their taxonomic status, morphological characteristics including male genitalia were examined and two mitochondrial genes, COI and 16S rDNA, and one nuclear 28S rDNA were analyzed. Molecular phylogenetic inferences indicated that both forms in both species are reciprocally monophyletic. Moreover, molecular dating showed the forms diverged approximately 1.3 million years ago. Two new species, Cylindera ooasp. nov. and Cylindera autumnalissp. nov., are thereby described. The main recognizable characteristics separating C. ooasp. nov. from C. sauteri are the lack of a triangular spot at the middle edge of elytron and the elongated but not rounded subapical spot. For C. autumnalissp. nov., the apical lunula near the elytral suture is thickened but not linear and slender, and its elytra are more metallic brownish than those of C. pseudocylindriformis. Although their aedeagi characteristics are not distinctive, the body size of the proposed two new species is different. Field observation revealed that niche utilization would be relevant for differentiating these closely related species.