Welcome back New Zealand: regional biogeography and Gondwanan origin of three endemic genera of mite harvestmen (Arachnida, Opiliones, Cyphophthalmi)

Aim Biogeographers have long been intrigued by New Zealand’s biota due to its unique combination of typical ‘continental’ and ‘island’ characteristics. The New Zealand plateau rifted from the former supercontinent Gondwana c. 80 Ma, and has been isolated from other land masses ever since. Therefore, the flora and fauna of New Zealand include lineages that are Gondwanan in origin, but also include a very large number of endemics. In this study, we analyse the evolutionary relationships of three genera of mite harvestmen (Arachnida, Opiliones, Cyphophthalmi) endemic to New Zealand, both to each other and to their temperate Gondwanan relatives found in Australia, Chile, Sri Lanka and South Africa. Location New Zealand (North Island, South Island and Stewart Island). Methods A total of 94 specimens of the family Pettalidae in the suborder Cyphophthalmi were studied, representing 31 species and subspecies belonging to three endemic genera from New Zealand (Aoraki, Neopurcellia and Rakaia) plus six other members of the family from Chile, South Africa, Sri Lanka and Australia. The phylogeny of these taxa was constructed using morphological and molecular data from five nuclear and mitochondrial genes (18S rRNA, 28S rRNA, 16S rRNA, cytochrome c oxidase subunit I and histone H3, totalling c. 5 kb), which were analysed using dynamic as well as static homology under a variety of optimality criteria. Results The results showed that each of the three New Zealand cyphophthalmid genera is monophyletic, and occupies a distinct geographical region within the archipelago, grossly corresponding to palaeogeographical regions. All three genera of New Zealand mite harvestmen fall within the family Pettalidae with a classic temperate Gondwanan distribution, but they do not render any other genera paraphyletic. Main conclusions Our study shows that New Zealand’s three genera of mite harvestmen are unequivocally related to other members of the temperate Gondwanan family Pettalidae. Monophyly of each genus contradicts the idea of recent dispersal to New Zealand. Within New Zealand, striking biogeographical patterns are apparent in this group of short‐range endemics, particularly in the South Island. These patterns are interpreted in the light of New Zealand’s turbulent geological history and present‐day patterns of forest cover.     

Biogeography of the world: a case study from cyphophthalmid Opiliones, a globally distributed group of arachnids

Aim To test the hypothesis that continental drift drives diversification of organisms through vicariance, we selected a group of primitive arachnids which originated before the break‐up of Pangaea and currently inhabits all major landmasses with the exception of Antarctica, but lacks the ability to disperse across oceanic barriers. Location Major continental temperate to tropical landmasses (North America, South America, Eurasia, Africa, Australia) and continental islands (Bioko, Borneo, Japan, Java, New Caledonia, New Guinea, New Zealand, Sri Lanka, Sulawesi, Sumatra). Methods Five kb of sequence data from five gene regions for more than 100 cyphophthalmid exemplars were analysed phylogenetically using different methods, including direct optimization under parsimony and maximum likelihood under a broad set of analytical parameters. We also used geological calibration points to estimate gross phylogenetic time divergences. Results Our analyses show that all families except the Laurasian Sironidae are monophyletic and adhere to clear biogeographical patterns. Pettalidae is restricted to temperate Gondwana, Neogoveidae to tropical Gondwana, Stylocellidae to Southeast Asia, and Troglosironidae to New Caledonia. Relationships between the families inhabiting these landmasses indicate that New Caledonia is related to tropical Gondwana instead of to the Australian portion of temperate Gondwana. The results also concur with a Gondwanan origin of Florida, as supported by modern geological data. Main conclusions By studying a group of organisms with not only an ancient origin, low vagility and restricted habitats, but also a present global distribution, we have been able to test biogeographical hypotheses at a scale rarely attempted. Our results strongly support the presence of a circum‐Antarctic clade of formerly temperate Gondwanan species, a clade restricted to tropical Gondwana and a Southeast Asian clade that originated from a series of early Gondwanan terranes that rifted off northwards from the Devonian to the Triassic and accreted to tropical Laurasia. The relationships among the Laurasian species remain more obscure.     

A morphometrics‐based phylogeny of the temperate Gondwanan mite harvestmen (Opiliones,Cyphophthalmi, Pettalidae)

A phylogenetic estimation of the temperate Gondwanan mite harvestman family Pettalidae (Arachnida, Opiliones, Cyphophthalmi) was conducted using 143 morphological variables (59 raw and 84 scaled measurements) from 37 ingroup and 15 outgroup terminals. We used custom algorithms to do pairwise comparisons between characters and identify sets of dependent characters, which were collapsed using principal components analysis. We analysed the resulting data without discretization under the parsimony criterion. Monophyly or paraphyly of most groups suspected from previous molecular and morphological phylogenetic studies were recovered. Trees were optimized for monophyly of 20 different focus clades by varying character phylogenetic independence. This yielded a final tree with monophyly of 15 out of 20 focus clades, including the South African pettalids, which contains the troglomorphic species Speleosiro argasiformis Lawrence, 1931. Two of the remaining five clades were found paraphyletic, with the genera Aoraki, Rakaia, and Siro always being found polyphyeletic.     

Phylogeny of magpie‐robins and shamas (Aves: Turdidae: Copsychus and Trichixos): implications for island biogeography in Southeast Asia

Aim Magpie‐robins and shamas are forest and woodland birds of south Asia. There are two genera: Trichixos for the monotypic T. pyrrhopygus, and Copsychus for other species. Two species are widespread, whereas the others are restricted to specific islands. Endemicity is highest in the Philippines. Using phylogenetic methods, we examined how this group came to its unusual distribution. Location Mainland Asia from India to southern China, and islands from Madagascar to the Philippines. Particular emphasis is placed on the Greater Sundas and Philippines. Methods The phylogeny was estimated from DNA sequences of 14 ingroup taxa representing all nine currently recognized Copsychus and Trichixos species. The entire mitochondrial ND2 gene and portions of nuclear myoglobin intron 2 (Myo2) and transforming growth factor beta 2 intron 5 (TGFβ2‐5) were sequenced for all but two species. The phylogeny was reconstructed using maximum likelihood and Bayesian methods. The timing of divergence events was estimated using a relaxed molecular clock approach, and ancestral areas were examined using stochastic modelling. Results The group comprises three main clades corresponding to ecological types: Trichixos, a primary‐forest specialist; Copsychus magpie‐robins, open‐woodland and coastal species; and Copsychus shamas, thick‐forest species. Trichixos appears to be sister to the magpie‐robins, rendering Copsychus polyphyletic. The dating of phylogenetic nodes was too ambiguous to provide substantial insight into specific geographical events responsible for divergence within the group. Some patterns are nevertheless clear. Copsychus shamas reached the Philippines, probably in two separate invasions, and split into endemic species. Copsychus malabaricus and C. saularis expanded widely in the Greater Sundas and mainland Southeast Asia without species‐level diversification. Main conclusions Magpie‐robins are excellent dispersers and have diversified into distinct species only on isolated oceanic islands. Trichixos, a poor disperser, is restricted to mature forests of the Malay Peninsula, Sumatra and Borneo. Copsychus shamas are intermediate in habitat preference and dispersal capabilities. Their endemism in the Philippines may be attributed to early colonization and specialization to interior forests. In the Greater Sundas, C. malabaricus and C. saularis populations split and came together on Borneo to form two separate subspecies (of each species), which now hybridize.     

Explosive evolution of an ancient group of Cyphophthalmi (Arachnida: Opiliones) in the Balkan Peninsula

Aim  To investigate the phylogeny of the genus Cyphophthalmus in the Balkan Peninsula and to test the current recognition of 'phyletic lines' and phylogenetic groups proposed in previous studies in order to elucidate the biogeographical history of the region.
Location  Europe, Balkan Peninsula, Adria microplate.
Methods  Two mitochondrial (cytochrome c oxidase subunit I and 16S rRNA) and two nuclear (28S rRNA and 18S rRNA) markers were used to infer the phylogenetic history of the group. Molecular dating with relaxed molecular clocks was used to elucidate the relative time of diversification within the genus Cyphophthalmus and its constituent lineages.
Results  Our analyses confirm the monophyly of the genus Cyphophthalmus , and that of the Aegean and gjorgjevici lineages, whereas the 'Dinaric lineage' appears paraphyletic.
Main conclusions  We show that the genus Cyphophthalmus is an old endemic from the Balkan biogeographical region, which gave origin to at least three main lineages. Those lineages have diversified within overlapping ranges. According to our molecular dating, they have also diversified within the same timeframe. The Dinaric Alps, although presenting a large number of species, cannot be inferred as the centre of origin of the group. Instead, the biogeographical evolution of the genus could be related to the palaeogeographic history of the Adria microplate.     

Insular radiation of the genus Hydropsyche (Insecta,Trichoptera: Hydropsychidae) Pictet, 1834 in the Philippines and its implications for the biogeography of Southeast Asia

Aims To record and elucidate the phylogeny and biogeography of a species swarm of the genus Hydropsyche (Insecta, Trichoptera) in the Philippines. All species belong to the hamifera group. Location The Philippines and neighbouring areas. Methods A phylogenetic analysis based on variation of morphological characters of the male phallic apparatus. Results The species swarm is differentiated into three clades of different age. Conclusion Alternative dispersal and vicariance hypotheses are considered in an attempt to explain the colonization of the Philippine archipelago and the subsequent ramification of the group. The vicariance hypothesis based on the late Miocene accretion of continental fragments to the Philippines appears to be the most parsimonious. The evolution of the swarm occurred on the Philippines. Later on species dispersed to Borneo, Sulawesi and the Moluccas. The species swarm has undergone an adaptive radiation which enabled the simultaneous occurrence of species in the same streams.     

West to east dispersal and subsequent rapid diversification of the mega‐diverse genus Begonia (Begoniaceae) in the Malesian archipelago

Aim The complex palaeogeography of the Malesian archipelago, characterized by the evolution of an ever‐changing mosaic of terrestrial and marine areas throughout the Cenozoic, provides the geographic backdrop for the remarkable diversification of Malesian Begonia (> 450 species). This study aimed to investigate the origin of Malesian Begonia, the directionality of dispersal events within the Malesian archipelago and the impact of ancient water gaps on colonization patterns, and to identify drivers of diversification. Location Asia, Southeast Asia, Malesia. Methods Plastid DNA sequence data of representatives of all families of the Cucurbitales and Fagales (matK, rbcL, trnL intron, trnL–F spacer, 4076 aligned positions, 92 taxa) and a sample of all major Asian Begonia sections (ndhA intron, ndhF–rpl32 spacer, rpl32–trnL spacer, 4059 aligned positions, 112 taxa) were analysed under an uncorrelated‐rates relaxed molecular clock model to estimate the age of the Begonia crown group divergence and divergence ages within Asian Begonia. Ancestral areas were reconstructed using a likelihood approach implementing a dispersal–extinction–cladogenesis model, and with a Bayesian approach to dispersal–vicariance analysis. Results The results indicated an initial diversification of Asian Begonia in continental Asia in the Miocene, and subsequent colonization of Malesia by multiple lineages. There was support for at least six independent dispersal events from continental Asia and western Malesia to Wallacea dating from the late Miocene to the Pleistocene. Begonia section Petermannia (> 270 species) originated in Western Malesia, and subsequently dispersed to Wallacea, New Guinea and the Philippines. Lineages within this section diversified rapidly since the Pliocene, coinciding with rapid orogenesis on Sulawesi and New Guinea. Main conclusions The predominant trend of Begonia dispersals between continental Asia and Malesia, and also within Malesia, has been from west to east. The water bodies separating the Sunda Shelf region from Wallacea have been porous barriers to dispersal in Begonia following the emergence of substantial land in eastern Malesia from the late Miocene onwards. We hypothesize two major drivers of the diversification of Malesian Begonia: (1) the formation of topographical heterogeneity and the promotion of microallopatry by orogenesis in the Pliocene and Pleistocene; and (2) cyclic vicariance by frequent habitat fragmentations and amalgamations due to climate and sea‐level fluctuations during the Pleistocene.     

Historical biogeography of Southeast Asia and the West Pacific,or the generality of unrooted area networks as historical biogeographic hypotheses

Aim Unrooted area networks are perhaps a general way in which different historical biogeographical patterns may be combined. Location Southeast Asia up to the West Pacific, Australia, South America. Methods Unrooted area networks based on Primary Brooks Parsimony Analysis of different data sets of Southeast Asian–West Pacific, Australian and South American clades. Results A large Brooks Parsimony historical (cladistic) biogeographic analysis of Southeast Asia and the West Pacific gave a meaningful result when all clades (representing different historical biogeographic patterns) were united into one matrix and an unrooted area network was produced. This network showed geographically adjacent areas as neighbours, which is interpreted as clades dispersing and speciating as soon as areas rafted towards each other. This pseudo‐vicariance mechanism, together with the very limited, mainly linear dispersal possibilities, a few large, widespread clades with many endemic species, and the large overlap in distributions displayed by different patterns, may explain the peculiar result. When applied to examples from other areas (bird data from Australia and South America), unrooted area networks for all data perform very poorly. Main conclusions Unrooted historical general area networks are not universally applicable. In general, it is better to split historical patterns a priori and analyse them separately.     

Pliocene climatic change in insular Southeast Asia as an engine of diversification in Ficedula flycatchers

Aims Insular Southeast Asia and adjacent regions are geographically complex, and were dramatically affected by both Pliocene and Pleistocene changes in climate, sea level and geology. These circumstances allow the testing of several biogeographical hypotheses regarding species distribution patterns and phylogeny. Avian species in this area present a challenge to biogeographers, as many are less hindered by barriers that may block the movements of other species. Widely distributed Southeast Asian avian lineages, of which there are many, have been generally neglected. Ficedula flycatchers are distributed across Eurasia, but are most diverse within southern Asia and Southeast Asian and Indo‐Australian islands. We tested the roles of vicariance, dispersal and the evolution of migratory behaviours as mechanisms of speciation within the Ficedula flycatchers, with a focus on species distributed in insular Southeast Asia. Methods Using a published molecular phylogeny of Ficedula flycatchers, we reconstructed ancestral geographical areas using dispersal vicariance analysis, weighted ancestral area analysis, and a maximum likelihood method. We evaluated the evolution of migratory behaviours using maximum likelihood ancestral character state reconstruction. Speciation timing estimates were calculated via local molecular clock methods. Results Ficedula originated in southern mainland Asia, c. 6.5 Ma. Our analyses indicate that two lineages within Ficedula independently and contemporaneously colonized insular Southeast Asia and Indo‐Australia, c. 5 Ma. The potential impact of vicariance due to rising sea levels is difficult to assess in these early colonization events because the ancestral areas to these clades are reconstructed as oceanic islands. Within each of these clades, inter‐island dispersal was critical to species’ diversification across oceanic and continental islands. Furthermore, Pliocene and Pleistocene climatic change may have caused the disjunct island distributions between several pairs of sister taxa. Both vicariance and dispersal shaped the distributions of continental species. Main conclusions This study presents the first evaluation, for Ficedula, of the importance of vicariance and dispersal in shaping distributions, particularly across insular Southeast Asia and Indo‐Australia. Although vicariant speciation may have initially separated the island clades from mainland ancestors, speciation within these clades was driven primarily by dispersal. Our results contribute to the emerging body of literature concluding that dynamic geological processes and climatic change throughout the Pliocene and Pleistocene have been important factors in faunal diversification across continental and oceanic islands.     

A chloroplast genealogy of myrmecophytic Macaranga species (Euphorbiaceae) in Southeast Asia reveals hybridization, vicariance and long-distance dispersals

Macaranga (Euphorbiaceae) includes about 280 species with a palaeotropic distribution. The genus not only comprises some of the most prominent pioneer tree species in Southeast Asian lowland dipterocarp forests, it also exhibits a substantial radiation of ant-plants (myrmecophytes). Obligate ant-plant mutualisms are formed by about 30 Macaranga species and 13 ant species of the genera Crematogaster or Camponotus. To improve our understanding of the co-evolution of the ants and their host plants, we aim at reconstructing comparative organellar phylogeographies of both partners across their distributional range. Preliminary evidence indicated that chloroplast DNA introgression among closely related Macaranga species might occur. We therefore constructed a comprehensive chloroplast genealogy based on DNA sequence data from the noncoding ccmp2, ccmp6, and atpB-rbcL regions for 144 individuals from 41 Macaranga species, covering all major evolutionary lineages within the three sections that contain myrmecophytes. A total of 88 chloroplast haplotypes were identified, and grouped into a statistical parsimony network that clearly distinguished sections and well-defined subsectional groups. Within these groups, the arrangement of haplotypes followed geographical rather than taxonomical criteria. Thus, up to six chloroplast haplotypes were found within single species, and up to seven species shared a single haplotype. The spatial distribution of the chloroplast types revealed several dispersals between the Malay Peninsula and Borneo, and a deep split between Sabah and the remainder of Borneo. Our large-scale chloroplast genealogy highlights the complex history of migration, hybridization, and speciation in the myrmecophytes of the genus Macaranga. It will serve as a guideline for adequate sampling and data interpretation in phylogeographic studies of individual Macaranga species and species groups.     

A molecular phylogeny of the temperate Gondwanan family Pettalidae (Arachnida,Opiliones, Cyphophthalmi) and the limits of taxonomic sampling

We evaluate the phylogenetic and biogeographical relationships of the members of the family Pettalidae (Opiliones, Cyphophthalmi), a textbook example of an ancient temperate Gondwanan taxon, by means of DNA sequence data from four markers. Taxon sampling is optimized to cover more than 70% of the described species in the family, with 117 ingroup specimens included in the analyses. The data were submitted to diverse analytical treatments, including static and dynamic homology, untrimmed and trimmed alignments, and a variety of optimality criteria including parsimony and maximum‐likelihood (traditional search and Bayesian). All analyses found strong support for the monophyly of the family Pettalidae and of all its genera, with the exception of Speleosiro, which is nested within Purcellia. However, the relationships among genera are poorly resolved, with the exceptions of a first split between the South African genus Parapurcellia and the remaining species, and, less supported, a possible relationship between Chileogovea and the other South African genus Purcellia. The diversification of most genera is Mesozoic, and of the three New Zealand genera, two show evidence of constant diversification through time, contradicting scenarios of total submersion of New Zealand during the Oligocene drowning episode. The genera Karripurcellia from Western Australia and Neopurcellia from the Australian plate of New Zealand show a pattern typical of relicts, with ancient origin, depauperate extant diversity and recent diversification. The following taxonomic actions are taken: Milipurcellia Karaman, 2012 is synonymized with Karripurcellia Giribet, 2003 syn. nov. ; Speleosiro Lawrence, 1931 is synonymised with Purcellia Hansen & Sørensen, 1904 syn. nov . The following new combinations are proposed: Parapurcellia transvaalica (Lawrence, 1963) comb. nov. ; Purcellia argasiformis (Lawrence, 1931) comb. nov .     

A phylogenetic and geotectonic scenario to explain the biogeography of the Lophopidae (Hemiptera, Fulgoromorpha)

The Lophopidae are found in South America, Africa, Australia, India and Southeast Asia. This distribution appears to be typically Gondwanan, triggered by tectonic events beginning over 100 Ma. However, within the Fulgoromorpha, the lophopids are considered to be relatively recently. In this study, biological, geological and phylogenetic information is evaluated to provide a parsimonious explanation for the distribution of the group and its geographic region of ancestral origin. The Lophopidae can be divided into four monophyletic groups. The ancestors of two groups appear to have originated somewhere along the western Pacific island arc system. Another group appears to have an origin in Southeast Asia. A reliable explanation for the ancestral origin of the fourth group was not possible because it consists of only one genus present in Central and South America. A biogeographic map of the two groups of lophids of the western Pacific island arc is concordant with their phylogeny based on biological and morphological data. Based on this finding, the best explanation for the origin and evolution of the Lophopidae and their current distribution of these lophopids is through vicariance. Similar types of eco-evolutionary events explain radiation and distribution of the Lophopidae, in general.     

Historical biogeography of the Southeast Asian and Malesian tribe Dissochaeteae (Melastomataceae)

The region of Tropical Southeast Asia and the Malay Archipelago is a very appealing area for research due to its outstanding biodiversity, being one of the most species-rich areas in the world with high levels of endemism, and due to its complex geological history. The high number of species in tribe Dissochaeteae (Melastomataceae) and their tendency to narrow endemism makethe tribe an ideal group for examining biogeographic patterns. We sampled 58 accessions spread over 42 accepted and two undescribed species of the Dissochaeteae. Two nuclear (ETS, ITS) and four chloroplast regions (ndhF, psbK-psbL, rbcL, rpl16) were used for divergence time estimation and ancestral area reconstruction. Results from the molecular dating analysis suggest that the diversity of Dissochaeteae in the Southeast Asian region resulted from a South American ancestor in the late Eocene. The ancestor of the Dissochaeteae might have migrated from South America to Southeast Asia via North America and then entered Eurasia over the North Atlantic land bridge during the Eocene. The origin and early diversification of the Dissochaeteae in Southeast Asia dates back to the middle Oligocene, and most of the genera originated during the Miocene. Indochina and Borneo are most likely the area of origin for the most recent common ancestor of the Dissochaeteae and for many of the early diverging clades of some genera within Southeast Asia.     

Minute moss beetles in the Southern Hemisphere: Molecular phylogeny,historical biogeography and habitat shifts (Coleoptera: Hydraenidae)

Minute moss beetles (Hydraenidae) are one of the most speciose and widespread families of aquatic Coleoptera, with an estimated 4000 extant species, found in the majority of aquatic habitats from coastal rock pools to mountain streams and from the Arctic Circle to the Antarctic islands. Molecular phylogenetic works have improved our understanding of the evolutionary history of the megadiverse Hydraena, Limnebius and Ochthebius in recent years, but most genera in the family have not yet been included in any phylogenetic analyses, particularly most of those which are restricted to the Southern Hemisphere. Using a multimarker molecular matrix, sampling over 40% of described species richness and 75% of currently recognized genera, we infer a comprehensive molecular phylogeny of these predominantly Gondwanan Hydraenidae. Whilst the genera we focus on are morphologically diverse, and currently classified across all four hydraenid subfamilies, our phylogenetic analyses suggest that these Gondwanan genera may instead constitute a single clade. As a result of our findings, the African genus Oomtelecopon Perkins syn.n. is shown to nest within Coelometopon Janssens, the New Zealand Homalaena Ordish syn.n. and Podaena Ordish syn.n. are synonymised with Orchymontia Broun, and the South African Pterosthetops Perkins syn.n. is synonymised with Prosthetops Waterhouse, resulting in Pterosthetopini Perkins syn.n. being synonymised with Prosthetopini Perkins. Mesoceratops Bilton & Jäch gen.n. is erected to accommodate six former members of Mesoceration Janssens, which is shown to be polyphyletic. We propose the replacement name Orchymontia ordishi Jäch & Bilton nom.n. for Homalaena dilatata Ordish, 1984 (now a junior homonym); altogether 39 new combinations are proposed. Our Bayesian divergence times infer an origin for this ‘Gondwana group’ of genera in Africa plus Madagascar in the mid-Cretaceous and suggest that both vicariant and dispersal processes, together with extinctions, have shaped the biogeographic history of these beetles in the Southern Hemisphere during the Cretaceous, resulting in geographically conserved extant lineages. Finally, we reconstruct ancestral habitat shifts across our phylogeny, revealing numerous changes in habitat occupancy in these genera, including multiple origins of fully terrestrial, humicolous taxa in different regions.     

Heavily exploited but poorly known: systematics and biogeography of commercially harvested pythons (Python curtus group) in Southeast Asia

More than 100000 blood pythons (brongersmai) and short-tailed pythons (curtus and breitensteini) are taken from Borneo and Sumatra each year for the commercial leather trade. Traditionally, all have been treated as a single polytypic species (Python curtus) , with three subspecies differing in colour, size and geographic distribution. Analyses of DNA sequences and morphological data clarify the phylogenetic relationships, taxonomy and biogeography of this group. The lineage is monophyletic, and each of the three subspecies differs from the other two both morphologically and genetically. Given the morphological and genetic distinctiveness of each taxon, we here elevate the three subspecies to full species status. Python brongersmai is the most distinctive in terms of colour (of the three, only brongersmai has colour-morphs that are red or orange), size (it grows to 2.6 m, vs. approx. 2.0 m for the other taxa), and scalation (e.g. brongersmai has <166 ventral scales, vs. <166 in the other taxa and has two supralabials over each orbit, vs. one supralabial for the other two taxa). In terms of cytochrome b mitochondrial DNA sequence data, brongersmai is almost as distant genetically from the short-tailed pythons (8.9% divergence) as is the reticulated python (P. reticulatus: 10.3% divergence). The other two taxa (P. breitensteini from Kalimantan and P. curtus from western and southern Sumatra) are closely related (3% divergence), despite their disjunct distribution (separated by P. brongersmai). Sea-level fluctuations provide a plausible biogeographic scenario to explain phylogenetic divergence within this lineage. Given the distinctiveness of the component taxa, and the ease with which even dried skins can be identified to species level (based on ventral counts), the managers of this important commercial resource should no longer treat the P. curtus group as a single biological taxon.