A so called “taxonomic impediment” has been recognized as a major obstacle to biodiversity research for the past two decades. Numerous remedies were then proposed. However, neither significant progress in terms of formal species descriptions, nor a minimum standard for descriptions have been achieved so far. Here, we analyze the problems of traditional taxonomy which often produces keys and descriptions of limited practical value. We suggest that phylogenetics and phenetics had a subtle and so far unnoticed effect on taxonomy leading to inflated species descriptions.

Trigonopterus weevils are widely distributed throughout Melanesia and hyperdiverse in New Guinea. They are a dominant feature in natural forests, with narrow altitudinal zonation. Their use in community ecology has been precluded by the “taxonomic impediment”. We sampled >6,500 specimens from seven areas across New Guinea; 1,002 specimens assigned to 270 morphospecies were DNA sequenced. Objective clustering of a refined dataset (excluding nine cryptic species) at 3% threshold revealed 324 genetic clusters (DNA group count relative to number of morphospecies = 20.0% overestimation of species diversity, or 120.0% agreement) and 85.6% taxonomic accuracy (the proportion of DNA groups that “perfectly” agree with morphology-based species hypotheses). Agreement and accuracy were best at an 8% threshold. GMYC analysis revealed 328 entities (21.5% overestimation) with 227 perfect GMYC entities (84.1% taxonomic accuracy). Both methods outperform the parataxonomist (19% underestimation; 31.6% taxonomic accuracy). The number of species found in more than one sampling area was highest in the Eastern Highlands and Huon (Sørensen similarity index 0.07, 4 shared species); ⅓ of all areas had no species overlap. Success rates of DNA barcoding methods were lowest when species showed a pronounced geographical structure. In general, Trigonopterus show high α and β-diversity across New Guinea. DNA barcoding is an excellent tool for biodiversity surveys but success rates might drop when closer localities are included. Hyperdiverse Trigonopterus are a useful taxon for evaluating forest remnants in Melanesia, allowing finer-grained analyses than would be possible with vertebrate taxa commonly used to date. Our protocol should help establish other groups of hyperdiverse fauna as target taxa for community ecology. Sequencing delivers objective data on taxa of incredible diversity but mostly without a solid taxonomic foundation and should help pave the road for the eventual formal naming of new species.

A species discovery and description pipeline to accelerate and improve taxonomy is outlined, relying on concise expert descriptions, combined with DNA sequencing, digital imaging, and automated wiki species page creation from the journal. One hundred and one new species of Trigonopterus Fauvel, 1862 are described to demonstrate the feasibility of this approach: T. aeneipennis sp. n., T. aeneus sp. n., T. agathis sp. n., T. agilis sp. n., T. amplipennis sp. n., T. ancoruncus sp. n., T. angulatus sp. n., T. angustus sp. n., T. apicalis sp. n., T. armatus sp. n., T. ascendens sp. n., T. augur sp. n., T. balimensis sp. n., T. basalis sp. n., T. conformis sp. n., T. constrictus sp. n., T. costatus sp. n., T. costicollis sp. n., T. crassicornis sp. n., T. cuneipennis sp. n., T. cyclopensis sp. n., T. dentirostris sp. n., T. discoidalis sp. n., T. dromedarius sp. n., T. durus sp. n., T. echinus sp. n., T. edaphus sp. n., T. eremitus sp. n., T. euops sp. n., T. ferrugineus sp. n., T. fusiformis sp. n., T. glaber sp. n., T. gonatoceros sp. n., T. granum sp. n., T. helios sp. n., T. hitoloorum sp. n., T. imitatus sp. n., T. inflatus sp. n., T. insularis sp. n., T. irregularis sp. n., T. ixodiformis sp. n., T. kanawiorum sp. n., T. katayoi sp. n., T. koveorum sp. n., T. kurulu sp. n., T. lekiorum sp. n., T. lineatus sp. n., T. lineellus sp. n., T. maculatus sp. n., T. mimicus sp. n., T. monticola sp. n., T. montivagus sp. n., T. moreaorum sp. n., T. myops sp. n., T. nangiorum sp. n., T. nothofagorum sp. n., T. ovatus sp. n., T. oviformis sp. n., T. parumsquamosus sp. n., T. parvulus sp. n., T. phoenix sp. n., T. plicicollis sp. n., T. politoides sp. n., T. pseudogranum sp. n., T. pseudonasutus sp. n., T. ptolycoides sp. n., T. punctulatus sp. n., T. ragaorum sp. n., T. rhinoceros sp. n., T. rhomboidalis sp. n., T. rubiginosus sp. n., T. rubripennis sp. n., T. rufibasis sp. n., T. scabrosus sp. n., T. scissops sp. n., T. scharfi sp. n., T. signicollis sp. n., T. simulans sp. n., T. soiorum sp. n., T sordidus sp. n., T. squamirostris sp. n., T. striatus sp. n., T. strigatus sp. n., T. strombosceroides sp. n., T. subglabratus sp. n., T. sulcatus sp. n., T. taenzleri sp. n., T. talpa sp. n., T. taurekaorum sp. n., T. tialeorum sp. n., T. tibialis sp. n., T. tridentatus sp. n., T. uniformis sp. n., T. variabilis sp. n., T. velaris sp. n., T. verrucosus sp. n., T. violaceus sp. n., T. viridescens sp. n., T. wamenaensis sp. n., T. wariorum sp. n., T. zygops sp. n.. All new species are authored by the taxonomist-in-charge, Alexander Riedel.

The fauna of Bali, situated immediately west of Wallace's Line, is supposedly of recent Javanese origin and characterized by low levels of endemicity. In flightlessTrigonopterusweevils, however, we find 100% endemism for the eight species here reported for Bali. Phylogeographic analyses show extensivein situdifferentiation, including a local radiation of five species. A comprehensive molecular phylogeny and ancestral area reconstruction of Indo-Malayan–Melanesian species reveals a complex colonization pattern, where the three Balinese lineages all arrived from the East, i.e. all of them transgressed Wallace's Line. Although East Java possesses a rich fauna ofTrigonopterus, no exchange can be observed with Bali. We assert that the biogeographic picture of Bali has been dominated by the influx of mobile organisms from Java, but different relationships may be discovered when flightless invertebrates are studied. Our results highlight the importance of in-depth analyses of spatial patterns of biodiversity.

The Sunda Arc forms an almost continuous chain of islands and thus a potential dispersal corridor between mainland Southeast Asia and Melanesia. However, the Sunda Islands have rather different geological histories, which might have had an important impact on actual dispersal routes and community assembly. Here, we reveal the biogeographical history of hyperdiverse and flightless Trigonopterus weevils. Different approaches to ancestral area reconstruction suggest a complex east to west range expansion. Out of New Guinea, Trigonopterus repeatedly reached the Moluccas and Sulawesi transgressing Lydekker′s Line. Sulawesi repeatedly acted as colonization hub for different segments of the Sunda Arc. West Java, East Java and Bali are recognized as distinct biogeographic areas. The timing and diversification of species largely coincides with the geological chronology of island emergence. Colonization was not inhibited by traditional biogeographical boundaries such as Wallace’s Line. Rather, colonization patterns support distance dependent dispersal and island age limiting dispersal.