We DNA barcoded 2,597 parasitoid wasps belonging to 6 microgastrine braconid genera reared from parapatric tropical dry forest, cloud forest, and rain forest in Area de Conservación Guanacaste (ACG) in northwestern Costa Rica and combined these data with records of caterpillar hosts and morphological analyses. We asked whether barcoding and morphology discover the same provisional species and whether the biological entities revealed by our analysis are congruent with wasp host specificity. Morphological analysis revealed 171 provisional species, but barcoding exposed an additional 142 provisional species; 95% of the total is likely to be undescribed. These 313 provisional species are extraordinarily host specific; more than 90% attack only 1 or 2 species of caterpillars out of more than 3,500 species sampled. The most extreme case of overlooked diversity is the morphospecies Apanteles leucostigmus . This minute black wasp with a distinctive white wing stigma was thought to parasitize 32 species of ACG hesperiid caterpillars, but barcoding revealed 36 provisional species, each attacking one or a very few closely related species of caterpillars. When host records and/or within-ACG distributions suggested that DNA barcoding had missed a species-pair, or when provisional species were separated only by slight differences in their barcodes, we examined nuclear sequences to test hypotheses of presumptive species boundaries and to further probe host specificity. Our iterative process of combining morphological analysis, ecology, and DNA barcoding and reiteratively using specimens maintained in permanent collections has resulted in a much more fine-scaled understanding of parasitoid diversity and host specificity than any one of these elements could have produced on its own.

Insect parasitoids are a major component of global biodiversity and affect the population dynamics of their hosts. However, identification of insect parasitoids is often difficult, and they are suspected to contain many cryptic species. Here, we ask whether the cytochrome c oxidase I DNA barcode could function as a tool for species identification and discovery for the 20 morphospecies of Belvosia parasitoid flies (Diptera: Tachinidae) that have been reared from caterpillars (Lepidoptera) in Area de Conservación Guanacaste (ACG), northwestern Costa Rica. Barcoding not only discriminates among all 17 highly host-specific morphospecies of ACG Belvosia , but it also raises the species count to 32 by revealing that each of the three generalist species are actually arrays of highly host-specific cryptic species. We also identified likely hybridization among Belvosia by using a variable internal transcribed spacer region 1 nuclear rDNA sequence as a genetic covariate in addition to the strategy of overlaying barcode clusters with ecological information. If general, these results will increase estimates of global species richness and imply that tropical conservation and host–parasite interactions may be more complex than expected.

Many species of tachinid flies are viewed as generalist parasitoids because what is apparently a single species of fly has been reared from many species of caterpillars. However, an ongoing inventory of the tachinid flies parasitizing thousands of species of caterpillars in Area de Conservación Guanacaste, northwestern Costa Rica, has encountered >400 species of specialist tachinids with only a few generalists. We DNA-barcoded 2,134 flies belonging to what appeared to be the 16 most generalist of the reared tachinid morphospecies and encountered 73 mitochondrial lineages separated by an average of 4% sequence divergence. These lineages are supported by collateral ecological information and, where tested, by independent nuclear markers (28S and ITS1), and we therefore view these lineages as provisional species. Each of the 16 apparently generalist species dissolved into one of four patterns: ( i ) a single generalist species, ( ii ) a pair of morphologically cryptic generalist species, ( iii ) a complex of specialist species plus a generalist, or ( iv ) a complex of specialists with no remaining generalist. In sum, there remained 9 generalist species among the 73 mitochondrial lineages we analyzed, demonstrating that a generalist lifestyle is possible for a tropical caterpillar parasitoid fly. These results reinforce the emerging suspicion that estimates of global species richness are likely underestimates for parasitoids (which may constitute as much as 20% of all animal life) and that the strategy of being a tropical generalist parasitic fly may be yet more unusual than has been envisioned for tachinids.

Inventory of the caterpillars, their food plants and parasitoids began in 1978 for today's Area de Conservacion Guanacaste (ACG), in northwestern Costa Rica. This complex mosaic of 120 000 ha of conserved and regenerating dry, cloud and rain forest over 0–2000 m elevation contains at least 10 000 species of non‐leaf‐mining caterpillars used by more than 5000 species of parasitoids. Several hundred thousand specimens of ACG‐reared adult Lepidoptera and parasitoids have been intensively and extensively studied morphologically by many taxonomists, including most of the co‐authors. DNA barcoding — the use of a standardized short mitochondrial DNA sequence to identify specimens and flush out undisclosed species — was added to the taxonomic identification process in 2003. Barcoding has been found to be extremely accurate during the identification of about 100 000 specimens of about 3500 morphologically defined species of adult moths, butterflies, tachinid flies, and parasitoid wasps. Less than 1% of the species have such similar barcodes that a molecularly based taxonomic identification is impossible. No specimen with a full barcode was misidentified when its barcode was compared with the barcode library. Also as expected from early trials, barcoding a series from all morphologically defined species, and correlating the morphological, ecological and barcode traits, has revealed many hundreds of overlooked presumptive species. Many but not all of these cryptic species can now be distinguished by subtle morphological and/or ecological traits previously ascribed to ‘variation’ or thought to be insignificant for species‐level recognition. Adding DNA barcoding to the inventory has substantially improved the quality and depth of the inventory, and greatly multiplied the number of situations requiring further taxonomic work for resolution.

Amphibians are frequently characterized as having limited dispersal abilities, strong site fidelity and spatially disjunct breeding habitat. As such, pond‐breeding species are often alleged to form metapopulations. Amphibian species worldwide appear to be suffering population level declines caused, at least in part, by the degradation and fragmentation of habitat and the intervening areas between habitat patches. If the simplification of amphibians occupying metapopulations is accurate, then a regionally based conservation strategy, informed by metapopulation theory, is a powerful tool to estimate the isolation and extinction risk of ponds or populations. However, to date no attempt to assess the class‐wide generalization of amphibian populations as metapopulations has been made. We reviewed the literature on amphibians as metapopulations (53 journal articles or theses) and amphibian dispersal (166 journal articles or theses for 53 anuran species and 37 salamander species) to evaluate whether the conditions for metapopulation structure had been tested, whether pond isolation was based only on the assumption of limited dispersal, and whether amphibian dispersal was uniformly limited. We found that in the majority of cases (74%) the assumptions of the metapopulation paradigm were not tested. Breeding patch isolation via limited dispersal and/or strong site fidelity was the most frequently implicated or tested metapopulation condition, however we found strong evidence that amphibian dispersal is not as uniformly limited as is often thought. The frequency distribution of maximum movements for anurans and salamanders was well described by an inverse power law. This relationship predicts that distances beneath 11–13 and 8–9 km, respectively, are in a range that they may receive one emigrating individual. Populations isolated by distances approaching this range are perhaps more likely to exhibit metapopulation structure than less isolated populations. Those studies that covered larger areas also tended to report longer maximum movement distances – a pattern with implications for the design of mark‐recapture studies. Caution should be exercised in the application of the metapopulation approach to amphibian population conservation. Some amphibian populations are structured as metapopulations – but not all.

Thirty-five species of the genus Houghia Coquillett (Tachinidae, Exoristinae, Goniini) are described, 34 new and one previously described, all reared from -various species of caterpillars collected in Area de Conservación Guanacaste (ACG), northwestern Costa Rica. A matrix of character states and a key for the identification of the species are also provided. By coupling morphology, life history and molecular data, with photographic documentation, a clear and concise description of each species is provided. The following 34 new species of Houghia are described, all authored by Fleming and Wood: H. aerata sp. nov., H. aurifera sp. nov., H. biseriata sp. nov., H. bivittata sp. nov., H. blancoi sp. nov., H. brevipilosa sp. nov., H. chavarriae sp. nov., H. confinis sp. nov., H. delospilota sp. nov., H. destituta sp. nov., H. fimbriata sp. nov., H. gracilis sp. nov., H. graciloides sp. nov., H. griseifrons sp. nov., H. inflatipalpis sp. nov., H. latigena sp. nov., H. latilobus sp. nov., H. longicercus sp. nov., H. longipilosa sp. nov., H. luteiventris sp. nov., H. macilenta sp. nov., H. marini sp. nov., H. matarritai sp. nov., H. nigrofemur sp. nov., H. ochrofemur sp. nov., H. omissa sp. nov., H. pallida sp. nov., H. parmata sp. nov., H. pilosifrons sp. nov., H. romeroae sp. nov., H. sexmaculata sp. nov., H. spathulata sp. nov., H. triangularis sp. nov., and H. velutina sp. nov. The following are proposed by Wood as new synonyms of Houghia: Actinoprosopa Townsend syn. nov., Agrarialia Curran syn. nov., Anhangabahuia Townsend syn. nov., Aridalia Curran syn. nov., Bolohoughia Townsend syn. nov., Carceliocephala Townsend syn. nov., Chrysohoughia Townsend syn. nov., Eumacrohoughia Townsend syn. nov., Macrohoughia Townsend syn. nov., Orohoughia Townsend syn. nov., Pammaerus Aldrich syn. nov., Pararrhinactia Townsend syn. nov., Petrargyrops Townsend syn. nov., Sisyrohoughia Townsend syn. nov., Tapajohoughia Townsend syn. nov., and Verrugomyia Townsend syn. nov. New combinations are proposed by Wood as a result of the new synonymies, as follows: H. analis (Townsend) comb. nov., H. approximata (van der Wulp) comb. nov., H. aurata (Townsend) comb. nov., H. aurometallica (Townsend) comb. nov., H. bistrigata (van der Wulp) comb. nov., H. calcarata (van der Wulp) comb. nov., H. chlorescens (Townsend) comb. nov., H. crypta (Townsend) comb. nov., H. facialis (Townsend) comb. nov., H. impedita (van der Wulp) comb. nov., H. lateralis (Curran) comb. nov., H. leptotrichopa (Brauer & Bergenstamm) comb. nov., H. maris (Townsend) comb. nov., H. marmorata (Townsend) comb. nov., H. minor (Thompson) comb. nov., H. nuda (Townsend) comb. nov., H. orbitalis (Townsend) comb. nov., H. orbitalis (Curran) comb. nov., H. parva (Townsend) comb. nov., H. plagioides (van der Wulp) comb. nov., H. punctiger (Townsend) comb. nov., H. quadra (Wiedemann) comb. nov., H. sexualis (Curran) comb. nov., H. similis (Townsend) comb. nov., H. simillima (Thompson) comb. nov., H. sordida (van der Wulp) comb. nov., H. tenuiseta (Macquart) comb. nov., and H. tropica (Townsend) comb. nov. Houghia orbitalis (Curran, 1934a, described in Sturmia), junior homonym of H. orbitalis (Townsend, 1927, described in Verrugomyia) is synonymized by Wood with Houghia leptotrichopa (Brauer & Bergenstamm, 1891), and need not be renamed while in synonymy. Lectotypes are designated by Wood for the following ten valid species of Houghia: Anisia approximata van der Wulp, 1890, Actinoprosopa facialis Townsend, 1927, Masicera impedita van der Wulp, 1890, Macrohoughia marmorata Townsend, 1927, Eumacrohoughia minor Thompson, 1963, Prospherysa plagioides van der Wulp, 1890, Petrargyrops punctiger Townsend, 1927, Carceliocephala simillima Thompson, 1963, Masicera sordida van der Wulp, 1890, and Masicera tenuiseta Macquart, 1846: 292.