Zoological Journal of the Linnean Society

This study aims to discriminate cercopithecid taxa of higher taxonomic levels (subfamily, tribe, subtribe, and genus) on the basis of corpus shape in transverse cross-section at the M1-M2 junction and to assess its variation using 2D geometric morphometrics. Specifically, we evaluated the effect of allometry and sexual dimorphism on differences in corpus shape at interspecific and intraspecific levels, respectively. We also investigated whether corpus variation among cercopithecids was following Brownian motion using Pagels {lambda}. Taxonomic discrimination and sexual dimorphism were established using Analysis of Variance on Principal Component scores. Allometry was studied using phylogenetic least-squares regressions and partial least-squares regressions. We demonstrated that, using corpus shape, extant cercopithecids can be significantly discriminated at the subfamilial, tribal, and subtribal levels. In addition, the main axis of variation of the Principal Component Analysis follows a distribution expected under Brownian motion, validating the presence of a phylogenetic signal in corpus shape. Colobines exhibit a robust corpus (superoinferiorly short and transversely broad) with large lateral prominences while cercopithecines have a gracile corpus (superoinferiorly long and transversely thin in its distal portion) with marked corpus fossae in African papionins. Exception to the typical subfamilial or tribal shape pattern exist, with the best examples being Trachypithecus, Presbytis and Pygathrix within colobines, Allenopithecus within Cercopithecini, and Macaca, Theropithecus and Cercocebus within Papionini. Sexual dimorphism is a confounding factor in shape discrimination, as there are significant differences between sexes, notably in Papio anubis, Nasalis larvatus and Procolobus verus . Intriguingly, sexual dimorphism in corpus shape does not seem to follow the dimorphism deduced in canine and molar crown dimensions. This discrepancy is illustrated by the low degree of dimorphism in corpus shape in Piliocolobus badius, despite dimorphic canine and molar dimensions. Overall, our findings concerning corpus shape variation in cercopithecids will greatly benefit to paleontological studies that seek to identify taxa in the fossil record, and to neontological studies aiming to explore the ecomorphological value of the cercopithecid mandible.

The symphyseal anatomy of extant and fossil cercopithecids has not yet been demonstrated as a useful tool for taxonomic discrimination, and the source of variation in cercopithecid symphysis has not been addressed on a broad taxonomic scale. Here, we used linear and angular dimensions to quantify symphysis shape. Using univariate, multivariate data and allometric regressions (partial least squares and phylogenetic generalized least square regressions), we addressed the hypothesis that extant cercopithecids can be distinguished by symphysis shape. Significant differences in univariate and multivariate data and allometric regressions permitted to distinguish cercopithecids at the subfamilial, tribal, and genus levels. We showed that multivariate data followed the distribution expected under Brownian Motion and significantly discriminates taxa at different taxonomic levels. Colobine symphysis are characterized by developed inferior transverse tori, short planum alveolare, and short symphysis, whereas cercopithecine symphysis are characterized by developed superior transverse tori, long planum alveolare, and long symphysis. Exceptions to this pattern exist within each subfamily, and this study underlines the particular anatomy of Colobus and Presbytis among the colobines, Allenopithecus among the Cercopithecini, and Theropithecus and Lophocebus among the Papionini. We also demonstrate that the relative development of the transverse tori, the relative length of the planum alveolare and symphyseal inclination are dimorphic traits. Specifically, we show that the symphysis of Procolobus verus, Nasalis larvatus, and Papio anubis is strongly dimorphic.

Species-level delimitation within the genus Trichomycterus remains one of the main systematic challenges within the Trichomycterinae, particularly in lineages characterised by conservative external morphology, high apparent intraspecific variation, and historical diagnostic criteria based primarily on body proportions, colouration and a few meristic characters. In central Chile, Trichomycterus areolatus has traditionally been interpreted as a widely distributed and morphologically variable species, whilst T. maculatus, originally described from "Santiago du Chili", has remained subordinate to this broad conception without a modern phylogenetic reassessment. Here we reassess the specific boundaries of T. areolatus sensu lato using an integrative approach that combines complete mitogenomes, estimates of genetic divergence and comparative morphology of the cephalic laterosensory system associated with the neurocranium. Phylogenetic analyses reveal T. areolatus sensu lato to be non-monophyletic and identify a deeply divergent lineage, geographically coherent and attributable to T. maculatus. This lineage differs from restricted T. areolatus by extensive mitochondrial divergence, comparable to that observed between recognised species of Trichomycterinae, and by discrete characters of the cephalic lateral line system, primarily related to the continuity of the supraorbital canal and the arrangement of the associated pores. The congruence between mitogenomic, nuclear and morphological evidence supports the revalidation of Trichomycterus maculatus Valenciennes, 1846, and calls for a more restricted geographic circumscription of T. areolatus. These results demonstrate that the diversity of Trichomycterinae in central Chile has been underestimated, modify previous interpretation of the distribution of the species involved, and highlight the value of integrating mitogenomics and neurocranial/laterosensory characters into the taxonomy of morphologically conservative siluriform lineages.

Ctenomys Blainville 1826 ranks among the top ten most diverse mammal genera in terms of species richness. However, the taxonomic history of Ctenomys brasiliensis Blainville,1826, the corresponding type species, has long been obscured by a dearth of information regarding the collection data of the type material, compounded by an elusive geographic origin. Here, employing ancient DNA methodology, we sequenced the complete mitogenome of the remaining type specimen and conducted an extensive historical investigation to correlate originally described locality names with present-day locales in South America. Our analysis unequivocally confirms that the type specimen corresponds to the species currently designated as Ctenomys minutus Nehring, 1887. This resolution lays to rest a century-old debate surrounding the provenance of the type specimen, rejecting prior hypotheses that placed its collection site in southeastern Brazil or Uruguay. Instead, our evidence suggests it was likely obtained from a third location in southernmost Brazil. Previous analyses overlooked this new location due to confusion surrounding geographic nomenclature and labeling errors, issues rectified by our combined mitogenomic and historical approach. Furthermore, quantitative morphological analyses boost our findings, demonstrating a closer affinity between C. brasiliensis and C. minutus within the same species group. Accordingly, we validate C. brasiliensis and propose C. minutus as its junior synonym. Our study underscores the importance of robust DNA analyses in confirming the identity and geographic origins of type specimens, especially for Ctenomys species with similar phenotypes, and specimens collected centuries ago.

Polytypic species with large ranges may harbor unrecognized diversity because taxonomy ranks populations differing subtly in plumage as subspecies. The Ruddy Foliage-gleaner (Clibanornis rubiginosus) exemplifies this problem. It ranges from Mexico to Brazil, with 15 subspecies, and forms a non-monophyletic complex with two congeners, yet its songs had not been compared. We measured ten spectral and temporal variables on 104 recordings covering 14 of 15 subspecies. Bayesian linear mixed models showed three song groups: eight subspecies west of the Andes share a single-note song, whereas Amazonian and Guianan populations add a short introductory note and sing longer, lower-pitched songs. Within this group, watkinsorum sings the lowest-pitched and longest song and is phylogenetically closer to C. cinnamomeigula than to its Amazonian neighbors. The third group is C. cinnamomeigula alone, a white-eyed taxon in an otherwise dark-eyed group. Its high-pitched, vibrato song resembles none other in the genus. One-note and two-note songs differ in kind without intermediates, and every two-note taxon sequenced to date falls in one clade, so C. rubiginosus is paraphyletic. We recognize four species, C. rubiginosus sensu stricto, C. cinnamomeigula, C. watkinsorum, and C. obscurus. This raises Clibanornis from five species to eight and divides its only polytypic species.

Thanks to its dynamic geological history the Ponto-Caspian region harbors a unique and unusually adaptable fauna, notorious for its invasive species. Gammarid amphipods attained considerable diversity, becoming the worlds second most speciose ancient-lake amphipod radiation. Nonetheless, apart from a few invasive species, this group remains poorly studied. Herein, we review and quantify the taxonomic, morphological and ecological diversity, as well as phylogenetic context of Ponto-Caspian gammarids within the adaptive radiation framework. Published molecular phylogenies indicate that this radiation has a monophyletic mid-Miocene Paratethyan origin, and is nested within the morphologically-conserved Atlanto-Mediterranean genus Echinogammarus. We find extensive disparity in body shape, size, ornamentation and appendage length, along a broad ecological gradient from mountain springs to depths exceeding 500 m, on virtually all substrate types (including symbiosis). We propose four putative ecomorphs that appear convergent with distantly related oceanic and Baikal Lake taxa. Thus, the identified patterns support the adaptive radiation model, although extensive further research is needed. A checklist and provisional key to all known endemic species are provided to facilitate taxonomic research. Ponto-Caspian gammarids could be a potentially powerful model for studying adaptive radiations and invasive species evolution.

The Nechisar Nightjar Caprimulgus solala was described only from a single wing collected as roadkill from Nechisar National Park in Ethiopia in 1990. To resolve its taxonomic status a sample was taken from the Nechisar Nightjar holotype and 53 other Afrotropical nightjars, and genomic DNA extracted for sequencing of one mitochondrial and three nuclear genes. The genetic analysis concluded that Nechisar Nightjar is most likely a hybrid, with mitochondrial DNA of Standard-winged Nightjar Caprimulgus longipennis and nuclear alleles from Standard-winged Nightjar and a second nightjar species that has not yet been sequenced. Morphometric and plumage analysis suggests that the paternal parent is Freckled Nightjar Caprimulgus tristigma, for which no nuclear sequence data are currently available.

Our study provides the first comprehensive karyotype evolution analysis of the insect order Zoraptera. We present karyotypic descriptions of seven species across two families: Zorotypidae (Usazoros hubbardi and two Zorotypus spp.) and Spiralizoridae (Centrozoros gurneyi, Spiralizoros magnicaudelli, and two Spiralizorose spp.). These results facilitate a critical evaluation of existing cytogenetic knowledge in Zoraptera and the evolution of karyotypic traits across Polyneoptera. Most notably, we refute the presence of holocentric chromosomes in Zoraptera. Also, we show that the XY sex chromosome system is prevalent and likely ancestral within the order. Furthermore, by integrating the chromosome numbers of the studied species with a dated molecular phylogeny of Zoraptera, we provide the first estimation of the mode of chromosome number evolution for this group. Finally, standard karyotypic features (2n, chromosome morphology, and size) and the distribution of 18S rDNA and (TTAGG) telomeric motif clusters--detected by fluorescence in situ hybridization--reveal highly differentiated karyotypes and genomic structures. This genetic diversity contrasts sharply with the recognized morphological uniformity of Zoraptera.

In birds, the quadrate bone serves as a hinge articulating with the lower jaw and the skull, playing an important mechanical role in the feeding apparatus. Avian cranial kinesis is dependent on the streptostylic quadrate transferring force from the adductor muscles at the back of the skull toward the beak, as part of a four-bar mechanical linkage to elevate and depress the bill. The complex morphology of the bird quadrate has led to authors adopting a range of alternative terminologies to describe the same anatomical structures and character states, impeding clarity of communication and presenting a barrier to progress in our understanding of the evolution of this important component of the avian feeding apparatus. Here, we reconcile terminological discord among previous studies on avian quadrate morphology and propose a stable nomenclature for future work. To characterise the considerable variation in quadrate form across crown bird diversity, we present an extensive anatomical atlas of the avian quadrate and summarise major patterns of quadrate morphological variation across extant avian phylogeny. In addition, we investigate macroevolutionary patterns in avian quadrate morphology, incorporating comparisons of crown birds and Late Cretaceous near-crown stem birds. We demonstrate that quadrate characters are useful for diagnosing a range of major avian subclades, and suggest that numerous distinctive features are likely to be associated with important biomechanical consequences. This investigation has implications for resolving the unsettled phylogenetic relationships of extinct bird clades such as Pelagornithidae and Gastornithiformes, as well as controversial relationships within several extant groups.

We present here the first observation of Bipalium admarginatum de Beauchamp, 1933 since its original description 90 years ago. Three specimens were found on Perhentian Kecil Island, off Terengganu State, Malaysia and photographed in the field, and two were collected. This report thus includes the first colour photographs published for this species, from a locality close to the type-locality, Tioman Island (which is ca. 200 km south of the locality in this study, on the east coast of Peninsula Malaysia). We describe the external morphology and colour pattern of the species, which correspond well to the original description, itself based only on two preserved specimens. We performed an in-depth molecular characterisation of the species, including its complete mitochondrial genome, the 18S sequence and elongation 1 alpha sequence. In addition, EF1a sequences were also retrieved for 5 additional geoplanid species. No tRNA-Thr could be detected in the mitogenome of B. admarginatum, a lack already reported in several species of geoplanids, but we found a 13 bp sequence that contains the anticodon loop and seems to be conserved among geoplanids and might thus possibly represent a non-canonical undetected tRNA. We discuss the difficulties encountered in trying to reconstruct the cluster of nuclear ribosomal genes, a problem already mentioned for other Triclads. Three phylogenies, based respectively on all mitochondrial proteins, 18S, and EF1a, were computed; the position of B. admarginatum within the Bipaliinae was confirmed in each tree, as sister-group to various bipaliine species according to the sequences available for each tree.

The African Clawed Frog Xenopus laevis, a global invader, exhibits marked phylogeographic divergence among native populations in southern Africa, which enhances its invasive potential. The polystomatid flatworm Protopolystoma xenopodis, as the frogs most frequently co-introduced metazoan parasite, may be the ideal biological tag for the frogs movement, if corresponding divergence can be demonstrated. In an integrative approach, we utilised morphometrics and molecular markers to assess divergence in P. xenopodis in its native range. We measured twelve key morphological characters from 23 flatworms and compared these statistically between flatworms collected to the north and south of the Great Escarpment Mountain Range in South Africa. Phylogenetic analyses were based on three concatenated markers, namely 28S and 12S rDNA and COX1, from six flatworms. The combination of five morphological characters, which involve egg size, gut morphology and size of the attachment hooks, differentiated northern and southern populations of P. xenopodis in South Africa. The multilocus phylogenetic analyses supported these findings, showing a well-supported cluster of northern P. xenopodis. These findings suggest that taxonomic studies of polystomatid flatworms should make use of geographically representative data sets that consider both morphological and molecular evidence. Moreover, the findings demonstrate that the frog host and flatworm parasite exhibit corresponding phylogeographic structuring in the native range. Consequently, the phylogeography of P. xenopodis, both in the native and invasive range of its host, may act as a key piece of evidence to reconstruct past invasion pathways of X. laevis.

Taxonomic uncertainty at the species level compromises our knowledge of biodiversity, conservation and systematics. The impact of such uncertainty is heightened in megadiverse regions such as Amazonia due to high levels of cryptic diversity. We used integrative taxonomy based on newly collected topotypical specimens to redescribe the Amazonian nurse frog Allobates gasconi and infer its phylogenetic relationships. This species was described in 2002 based solely on morphology, but several characters crucial for the reliable diagnosis of species in Allobates were not considered. Our results show that A. gasconi sensu stricto is not a member of the A. caeruleodactylus clade as previously claimed, but is a member of the A. trilineatus clade. Allobates gasconi is readily distinguished from congeners by a combination of morphological and bioacoustic characters; a revised diagnosis is provided. The type series of A. gasconi comprises more than one species, and we exclude a paratype from lower Jurua River. The species is restricted geographically to flooded environments in the middle and upper Jurua River in Brazil and in the Ucayali River in Peru. The initial misidentification, subsequent absence of topotypic molecular and acoustic data, and the poor preservation condition of the type series have contributed to taxonomic confusion since A. gasconi was first described. The descriptions of other species of Allobates published more than two decades ago were based mainly on gross morphology and we recommend integrative taxonomic revisions to elucidate their systematics.

The greater blind mole rat S. microphthalmus is the only species that differs in the number of chromosomes (2n = 60) from the other species (2n = 62) of the genus Spalax. It also has the largest range among them. The intraspecific genetic and morphological variability of S. microphthalmus has been poorly studied so far. Previously, animals with 2n = 62 were found in the North Caucasus. This was interpreted as a manifestation of intraspecific polymorphism in greater blind mole rats. We investigated the morphometry, as well as the morphological, molecular, and chromosomal variability of S. microphthalmus using samples collected from across the entire range of the species. Genetic variability of S. microphthalmus was relatively low within the 2n = 60 karyotype range. A comparative, multi-proxy analysis of the species characteristics, as well as phylogenetic analyses within the genus Spalax was also performed. Species-level differences were found in all the characteristics studied in the karyotype of the blind mole rat (2n = 62) from the North Caucasus, compared with all the other Spalax species, including S. microphthalmus. A unique combination of morphological characteristics was described for this blind mole rat, including features that bring it closer to the hypothetical ancestor of all modern species of this genus. A new species is described on this basis: Spalax lyapunovae sp. nov. It is necessary to further study the range and the ecology of the new species, which is endemic to the central part of the North Caucasus.

Our paper is the first contribution to the comprehensive analysis of the complicated evolution of cranial and mandibular parts connected by pterygoid muscles, as part of more global investigation into adaptive evolution of Arvicolinae. The analysis was performed on 90 micro-computed-tomography-scanned specimens from 33 species from 19 genera of Arvicolinae as well as two species from two genera of Cricetinae as an outgroup. We revised 11 morphological traits of the "palato-spheno-pterygoid" complex, including key features of the palatine that are highly important for defining Arvicolinae taxa according to the micro-computed-tomography data. We also homologized characters of the posterior palatal margin and categorized the composition of the palatal elements into two main morphotypes: morphotype "A" is unique to Clethrionomyini and morphotype "B" was subdivided into three additional types and was found to occur in the outgroup (cricetines), voles (B2), and lemmings (B3). Morphospace analysis of the palato-spheno-pterygoid complex by means of the three-dimensional dataset revealed a mode of transformation of morphotype "A" into morphotype "B2." A separate task was the development of a protocol for the preparation of morphological data for subsequent evaluation of genotype-phenotype relationships using specialized software applications (e.g., RERconverge).

The life-cycle and polyp morphology of representatives of Margelopsidae are very different from all other species in the hydrozoan clade Aplanulata. Their evolutionary origin and phylogenetic position has been the subject of significant speculation. A recent molecular study based only on COI data placed Margelopsidae as a sister group to all Aplanulata, an unexpected result because margelopsid morphology suggests affiliation with Tubulariidae or Corymorphidae. Here we used multigene analyses, including nuclear (18S rRNA and 28S rRNA) and mitochondrial (16S rRNA and COI) markers of the hydroid stage of the margelopsid species Margelopsis haeckelii Hartlaub, 1897 and the medusa stage of Margelopsis hartlaubii Browne, 1903 to resolve their phylogenetic position with respect to other hydrozoans. Our data provide strong evidence that M. haeckelii, the type species of Margelopsis, is a member of the family Corymorphydae. In contrast, M. hartlaubii Browne, 1903 is sister to Plotocnide borealis Wagner, 1885, a member of Boreohydridae. These results invalidate the family Margelopsidae. The phylogenetic signal of polyp and medusa stages is discussed in light of concept of inconsistent evolution and molecular phylogenetic analysis.

Nematodes belonging to the Cystidicolidae Skrjabin, 1946 constitute more than 23 genera of 111 recognized species in fish from many habitats including the deep-sea, continental shelves, estuarine and freshwater habitats. The taxonomy of many species within the Cystidicolidae is unsettled due to their small size and correspondingly small morphological characters requiring use of scanning electron microscopy and supported more recently by molecular studies. The type species, Ascarophis morrhuae Van Beneden, 1870, which belongs to one of the first described and most speciose cystidicolid genera with 46 species, is based on a two-sentence description of a single female specimen from an Atlantic cod, Gadus morhua, presumably captured off the coast of Belgium in the North Sea (Van Beneden, 1870). New material was collected/examined from Atlantic cod and haddock, Melanogrammus aeglefinus, from Iceland and the North Sea and specimens present in the Natural History Museum, London were also studied. Based on these materials, A. morrhuae is morphologically redescribed and the first DNA sequences of this species are provided, it is differentiated from other Ascarophis species present in the North Atlantic and previous records are reviewed. This information provides a foundation for taxonomic and phylogenetic reconsideration of all cystidicolid nematodes and related families.

As biological shape is usually complex and evolves on different constraints, it can be assessed using integrative methods such as geometric morphometrics. Allometric changes were analysed in three species of Didelphis genus (D. albiventris n=20, D. marsupialis n=82, D. pernigra n=35) by means of geometric morphometric techniques. A significant correlation between shape and size was found, suggesting an allometric change pattern for all three species studied. However, allometries appeared to be different between D. marsupialis and D. pernigra, both of which belong to different groups (the so-called black-eared group and the white-eared group, respectively). Results are consistent with taxonomic recognition at the group level and can help to elucidate phylogenetic relationships between these three Didelphis species.

Saki monkeys (Pithecia) are found exclusively in the Amazon, ranging from the Guiana Shield in the east to the Andean foothills in the west. The taxonomy of this genus is complex due to indeterminate type localities, numerous synonyms, sexual dichromatism and considerable geographical diversity in coat colour patterns. Previous assessments have indicated two to four species and a variable few subspecies based on morphological analyses of museum specimens. Just two species have been consistently recognised--Pithecia pithecia and Pithecia monachus. This study presents the first comprehensive molecular phylogeny of the genus, using mitochondrial cytochrome b sequences from 137 individuals across their range and a ddRADseq genomic analysis on 34 individuals. The phylogenetic results revealed three main clades: (1) Guiana Shield sakis, (2) Sedimentary Basin and Brazilian Shield sakis, and (3) a basal P. albicans south of the Rio Solimoes. The ddRADseq data further clarified species boundaries and relationships, identifying six distinct species: P. chrysocephala and P. pithecia sensu Hershkovitz (1987) on the Guiana Shield; P. albicans in central Amazonia south of the Rio Solimoes; P. monachus in western Amazonia; P. irrorata between the rios Purus, Tapajos, and Juruena; and P. vanzolinii in a limited area east of the Rio Jurua.

The structure of phenotypic integration is predicted to bias the direction and rate of phenotypic evolution but only on timescales over which it is conserved. Both the scales on which the structure of integration evolves and how that structure is evolutionarily modified are important, but not generally understood. Here, structures of mandibular integration are inferred for eight species of "old endemic" Australian rodents, including a pair of intraspecific samples for two of these species. The structures of integration are compared and variation among these structures is assessed in light of the underlying phylogenetic relationships and in the finer patterns of conserved and evolving trait associations. Microevolution in the structure of integration is minor and while macroevolutionary comparisons almost all show significant similarity, comparisons range widely and do not clearly decay with the degree of phylogenetic separation. These patterns appear to reflect the combined influence of conserved and labile portions of the structure of integration. Structures of phenotypic integration are complexes of conserved and labile elements and if they bias phenotypic evolution, it will be in similarly complex ways.

The genus Gerbillus represents an example of the successful Pleistocene radiation among rodents, leading to the emergence of almost 50 currently recognized species inhabiting Asia (from the Middle East to northwest India) and Africa (the Saharo-Sahelian region and eastern Africa). During the last two decades, multiple molecular phylogenetic studies helped to decipher the complex subgeneric structure of this speciose group. However, questions concerning the number of phylogenetic lineages (species) within the genus and their evolutionary relationships remained open, especially because of the lack of genetic material from the Horn of Africa. Here we provide for the first time genetic information on Microdillus peeli (being for more than a hundred years a taxon with an unresolved phylogenetic position) and unequivocally show that it is an internal lineage of Gerbillus. Together with one additional newly characterized lineage of apparently subgenus rank (proposed here as subgenus "Pusillus"), endemic to Somali-Masai region in eastern Africa, these findings document that the Horn of Africa is the center of evolutionary diversity of gerbils in general, and of the genus Gerbillus in particular.