Discrete Morphotypes Research Articles

A fossil assemblage from the mid-late Maastrichtian of Gavdos Island, Greece, provides insights into the pre-extinction pelagic ichthyofaunas of the Tethys.

The global body-fossil record of marine 'fishes' from the time interval immediately preceding the Cretaceous-Paleogene Extinction is markedly poor. This deficiency appears to be further exacerbated with regards to offshore and deep-water taxa, obscuring our understanding of the state and composition of corresponding vertebrate faunas at the onset of this major extinction event. Recent fieldwork in the mid-late Maastrichtian exposures of the Pindos Unit in Gavdos Island, Greece, yielded a small but informative sample of fossil 'fishes', which inhabited the Tethys approximately three to four million years before the extinction. In this work we describe this sample, which comprises between eight and nine discrete morphotypes of various size classes, belonging to †Ichthyodectoidei, Aulopiformes (†Dercetidae, †Enchodontidae, †Ichthyotringidae), cf. †Sardinioididae, as well as the hexanchid shark †Gladioserratus sp. The new material expands the faunal list for the Maastrichtian of Gavdos Island, and the Pindos Unit as a whole, and further allows for the description of a new genus and species of †Enchodontidae and a new species of †Ichthyotringidae. The two new taxa are found to be widespread in the Maastrichtian of the Pindos Unit. The overall character of the assemblage agrees with previous interpretations of an offshore and rather deep depositional environment for the fossiliferous horizons. Furthermore, it exhibits a higher diversity than, and little taxonomic overlap with penecontemporaneous teleost assemblages from the Tethys, and informs on the otherwise poorly known Maastrichtian offshore and deep-water marine ichthyofaunas of the region.

Eco-morphological diversity of larvae of soldier flies and their closest relatives in deep time.

Stratiomyomorpha (soldier flies and allies) is an ingroup of Diptera, with a fossil record stretching back to the Early Cretaceous (the Barremian, about 125 MYA). Stratiomyomorpha includes at least 3,000 species in the modern fauna, with many species being crucial for ecosystem functions, especially as saprophages. Larvae of many stratiomyomorphans are especially important as scavengers and saproxyls in modern ecosystems. Yet, fossil larvae of the group are extremely scarce. Here we present 23 new records of fossil stratiomyomorphan larvae, representing six discrete morphotypes. Specimens originate from Cretaceous amber from Myanmar, Eocene Baltic amber, Miocene Dominican amber, and compression fossils from the Eocene of Messel (Germany) and the Miocene of Slovenia. We discuss the implications of these new records for our understanding of stratiomyomorphan ecomorphology in deep time as well as their palaeoecology.

Skeletal and muscular pelvic morphology of hillstream loaches (Cypriniformes: Balitoridae).

The rheophilic hillstream loaches (Balitoridae) of South and Southeast Asia possess a range of pelvic girdle morphologies, which may be attributed to adaptations for locomotion against rapidly flowing water. Specifically, the connectivity of the pelvic plate (basipterygium) to the vertebral column via a sacral rib, and the relative size and shape of the sacral rib, fall within a spectrum of three discrete morphotypes: long, narrow rib that meets the basipterygium; thicker, slightly curved rib meeting the basipterygium; and robust crested rib interlocking with the basipterygium. Species in this third category with more robust sacral rib connections between the basipterygium and vertebral column are capable of walking out of water with a tetrapod-like lateral-sequence, diagonal-couplet gait. This behavior has not been observed in species lacking direct skeletal connection between the vertebrae and the pelvis. The phylogenetic positions of the morphotypes were visualized by matching the morphological features onto a novel hypothesis of relationships for the family Balitoridae. The morphotypes determined through skeletal morphology were correlated with patterns observed in the pelvic muscle morphology of these fishes. Transitions towards increasingly robust pelvic girdle attachment were coincident with a more anterior origin on the basipterygium and more lateral insertion of the muscles on the fin rays, along with a reduction of the superficial abductors and adductors with more posterior insertions. These modifications are expected to provide a mechanical advantage for generating force against the ground. Inclusion of the enigmatic cave-adapted balitorid Cryptotora thamicola into the most data-rich balitorid phylogeny reveals its closest relatives, providing insight into the origin of the skeletal connection between the axial skeleton and basipterygium.

Ecophenotypic shape variability within Astarte (Class: Bivalvia) from the Pliocene of the Atlantic Coastal Plain, U.S.A.: A study using geometric morphometrics

The Atlantic Coastal Plain has long been recognized as a natural laboratory useful for testing hypotheses surrounding the environmental and ecological effects on marine fauna. To conduct these studies in a rigorous manner, a reliable taxonomy must be established for the organisms within this physiographic province. In this study, we focus on the bivalve genus Astarte, which is commonly found in this region, and has many formally recognized species. We test between two competing hypotheses for the unusually high species richness of this genus: 1) taxonomy – the presence of discrete morphotypes represent valid species within this genus; and, 2) ecology – the many recognized ‘species’ in this genus in fact represent ecophenotypic variants of a smaller number of species, and thus richness is inflated. We test between these two hypotheses using a geometric morphometric analysis of landmarks placed on 646 shells, representing six different taxa from the Pliocene of the Atlantic Coastal Plain. We performed Procrustes transformation and Principle Components Analysis (PCA) on landmark data, allometric residuals, and outline harmonics to fully understand the variability of morphologies present. All PCA results show large amounts of overlap between all species. It is likely some of these species are valid taxonomic groups within the genus but should be classified as sub-species instead of separate species. These results provide strong support for our ‘ecology’ hypothesis, and suggests the genus Astarte needs revision. Future studies incorporating detailed sedimentological characteristics or ecological information (e.g., drilling frequency) will further elucidate palaeoecological and palaeoenvironmental drivers of ecophenotypic variation present in this genus. Further, the accurate identification of fossil species has important implications for our ability to reconstruct biodiversity trends in relation to the emergence of the Central American Isthmus and subsequent changes in ocean circulation.

Genetic diversity and structure in Arapaima gigas populations from Amazon and Araguaia-Tocantins river basins

BackgroundArapaima gigas (Schinz, 1822) is the largest freshwater scaled fish in the world, and an emerging species for tropical aquaculture development. Conservation of the species, and the expansion of aquaculture requires the development of genetic tools to study polymorphism, differentiation, and stock structure. This study aimed to investigate genomic polymorphism through ddRAD sequencing, in order to identify a panel of single nucleotide polymorphisms (SNPs) and to simultaneously assess genetic diversity and structure in wild (from rivers Amazon, Solimões, Tocantins and Araguaia) and captive populations.ResultsCompared to many other teleosts, the degree of polymorphism in A. gigas was low with only 2.3% of identified RAD-tags (135 bases long) containing SNPs. A panel of 393 informative SNPs was identified and screened across the five populations. Higher genetic diversity indices (number of polymorphic loci and private alleles, Shannon’s Index and HO) were found in populations from the Amazon and Solimões, intermediate levels in Tocantins and Captive, and very low levels in the Araguaia population. These results likely reflect larger population sizes from less urbanized environments in the Amazon basin compared to Araguaia. Populations were significantly differentiated with pairwise FST values ranging from 0.086 (Amazon × Solimões) to 0.556 (Amazon × Araguaia). Mean pairwise relatedness among individuals was significant in all populations (P < 0.01), reflecting a degree of inbreeding possibly due to severe depletion of natural stocks, the species sedentary behaviour and possible sampling biases. Although Mantel test was not significant (P = 0.104; R2 = 0.65), Bayesian analysis in STRUCTURE and discriminant analysis of principal components (DAPC) showed populations of Amazon and Solimões to be genetically differentiated from Araguaia, with Tocantins comprising individuals from both identified stocks.ConclusionsThis relatively rapid genotyping by sequencing approach proved to be successful in delineating arapaima stocks. The approach and / or SNP panels identified should prove valuable for more detailed genetic studies of arapaima populations, including the elucidation of the genetic status of described discrete morphotypes and aid in delivery of conservation programs to maintain genetic diversity in reservoirs across the Amazon region.

A taxonomic revision of the genus Tanystropheus (Archosauromorpha, Tanystropheidae)

Tanystropheus represents one of the most characteristic genera of Triassic reptiles and is typified by easily recognizable, hyperelongate cervical vertebrae. First described in 1852, isolated cervical vertebrae and other remains have been referred to the genus and various species have been erected and rejected based on this material. This has resulted in a complicated and convoluted taxonomic history of the genus and confusion as to the validity of species and the referral of specimens. With the exception of the well-represented T. longobardicus, the five other species of Tanystropheus are known from isolated elements or a single, partial specimen. Here, we provide a complete overview of the taxonomic history and a revision of the genus based on first hand observations of the type material of most of the species. From this, we conclude that T. conspicuus and T. haasi should be considered nomina dubia and that T. meridensis constitutes a junior synonym to T. longobardicus. Furthermore, T. longobardicus can be subdivided into two discrete morphotypes that might represent separate species. However, a more detailed study is required to test this hypothesis. Finally, T. fossai is considered distinctly different from the other Tanystropheus taxa and is therefore referred to a separate genus, Sclerostropheus.

Combining geometric morphometrics and genetic analysis to identify species ofOpisthonemaGill, 1861 in the eastern Mexican Pacific

Studies focusing on the specific identification of the taxonomic cast within the genus Opisthonema are scarce and contradictory, in spite of this species commercial importance and of the potential ecological impact that fisheries may have on the pelagic ecosystem. In this study, the specific composition of thread herrings Opisthonema (O. bulleri, O. medirastre, and O. libertate) in the southeastern region of the Gulf of California was identified using meristic characters, morphometric data, and mtDNA sequences. In this paper we supported the hypothesis that the commercial catch comprises three evolutionary entities with meristic and morphometric differences. The results were based on the number of ceratobranchial gill rakers, the presence of spicules on the gill rakers, the form of insertion of the gill rakers base onto the ceratobranchial segment, the geometric morphometrics of body shape, and the genetic distances from a fragment of Cytochrome Oxidase Subunit I gene (COI) of mtDNA. Specimens of Pacific thread herring were obtained from landings of the small pelagic fleet at Mazatlan, Sinaloa during 2011–2012. Taxonomic categories were assigned to 1060 individuals according to the measurement of meristic characters. A total of 228 thread herrings O. bulleri, (n = 76), O. medirastre (n = 76), and O. libertate (n = 76) were used in the morphometric analysis, and 25 specimens (O. bulleri n = 8, O. medirastre n = 7, and O. libertate n = 10) were used for genetic comparisons. The morphometric results showed differences among the three groups that had been previously identified using meristic characters, giving support to the existence of three discrete morphotypes. The percentage of sequence divergence of the COI gene supports the existence of three clades. Genetic distances were considerably lower within each clade than between clades. The results of this study provide sufficient evidence for the existence of three Pacific thread herring species in the southern Gulf of California.

Large-scale diversification without genetic isolation in nematode symbionts of figs.

Diversification is commonly understood to be the divergence of phenotypes accompanying that of lineages. In contrast, alternative phenotypes arising from a single genotype are almost exclusively limited to dimorphism in nature. We report a remarkable case of macroevolutionary-scale diversification without genetic divergence. Upon colonizing the island-like microecosystem of individual figs, symbiotic nematodes of the genus Pristionchus accumulated a polyphenism with up to five discrete adult morphotypes per species. By integrating laboratory and field experiments with extensive genotyping of individuals, including the analysis of 49 genomes from a single species, we show that rapid filling of potential ecological niches is possible without diversifying selection on genotypes. This uncoupling of morphological diversification and speciation in fig-associated nematodes has resulted from a remarkable expansion of discontinuous developmental plasticity.

Ecological release leads to novel ontogenetic diet shift in kokanee (Oncorhynchus nerka)

We investigate adaptive resource polymorphism in kokanee (Oncorhynchus nerka) from Jo-Jo Lake, Alaska, by determining whether previously observed niche expansion occurs at the population or individual level. Utilizing morphological, genetic, and stable isotope techniques, we found no evidence of discrete trophic morphotypes as previously described, but instead found evidence for an ontogenetic diet shift. Carbon and nitrogen isotope data indicate a 40% decrease in the proportion of benthic feeding and an increase of one trophic position over the size and age ranges of adult kokanee, corresponding to a diet shift from consumption of macroinvertebrates in smaller individuals to piscivory in larger individuals. This novel piscivory in kokanee may result from predatory and competitive freedom resulting from the lack of limnetic predators in Jo-Jo Lake. Piscivorous feeding despite a phenotype–environment mismatch has resulted in large, piscivorous kokanee having up to 70% of their gill rakers damaged. Observed reductions in gill raker number relative to the putative ancestral population are convergent with expectations for piscivorous fishes, despite a presumed lack of standing genetic variation for piscivory in the sockeye salmon – kokanee species complex. Jo-Jo Lake kokanee are a distinctive example of adaptation in salmonids in response to ecological release. This unusual population highlights the importance of phenotypic plasticity in response to competition in shaping the adaptive landscape and altering evolutionary trajectories.

Ancient Bug Bites on Ancient Plants Record Forest Ecosystem Response to Environmental Perturbations

Leaf-compression fossils with insect feeding traces are unique in providing rich, direct evidence of two levels in a fossil food web. Plant-insect associations dominate terrestrial trophic interactions, emphasizing the need to understand their ecological and evolutionary history. This paper first discusses methods of recognizing insect herbivore damage on fossil leaves and quantifying fossil insect herbivory. By conducting an unbiased insect damage census, damage frequency (percent of leaves with insect feeding damage), percent of leaf surface area removed by insects, and damage diversity (the number of discrete damage morphotypes, or DTs, found on a fossil flora or individual host plant) can all be measured. Three examples of responses of past plant-insect trophic interactions to environmental stresses are examined. In the first case study, late Oligocene fossil floras from Ethiopia document forest response to local perturbation and key characteristics to recognize disturbance in the plant fossil record. The second case study considers the terrestrial ecosystem response to the catastrophic global perturbation at the Cretaceous–Paleogene boundary. In the third case study, the impact of past global warming events—including the Paleocene–Eocene Thermal Maximum—on insect herbivory is discussed. Productive avenues for further research include: insect damage studies conducted outside the North American Cretaceous and Paleogene, actualistic and taphonomic studies of insect herbivory, and tighter collaboration across paleobotany, paleoentomology, botany, and entomology.

Assessing the applicability of Emiliania huxleyi coccolith morphology as a sea‐surface salinity proxy

Culture experiments were used to assess the applicability of Emiliania huxleyi coccolith morphology as a palaeo‐sea‐surface salinity (SSS) proxy. Coccolith morphology was dependent on salinity over a range reflecting present day marine conditions; both coccolith size and the number of coccolith elements increased linearly with increasing salinity. Using regression analysis, the effect of salinity on coccolith morphology was compared to those previously observed in sediment core‐top and plankton data. No significant differences were found between the slopes of these data, suggesting that salinity is the primary control on E. huxleyi coccolith size and element number in the ocean. However, the intercepts of the culture data were significantly higher. A combination of experimental and literature analysis indicated that temperature and nutrients were unlikely to be the causes of this discrepancy. Literature analysis also highlighted that coccolith size data from marginal environments displayed different intercepts to those from the open‐ocean data. This suggests that discrete morphotypes exist in these marginal locations. We, therefore, recommend that the original E. huxleyi coccolith morphology palaeo‐SSS transfer function requires further evaluation before being routinely applied.

Cryptic species, phenotypic plasticity, and complex life histories: Assessing deep-sea faunal diversity with molecular markers

Many new species of animals have been discovered during the past 40 years of deep-ocean exploration, particularly in chemosynthetic habitats such as hydrothermal vents and cold-water hydrocarbon seeps. Estimating species diversity in these environments is difficult, however, because insufficient sampling often fails to capture the range of organismic variability in time and space. Molecular systematic studies have revealed a number of taxonomic problems that derive from insufficient sampling and a shallow knowledge base regarding many deep-sea taxa. For example, numerous morphologically cryptic species exist among the vesicomyid clams and lepetodrilid limpets that dominate vents and seeps worldwide, suggesting that species richness may be significantly underestimated in these taxa. In contrast, discrete morphotypes of siboglinid tubeworms that are products of developmental plasticity were assigned synonymous species names. Also, distinct juvenile and adult forms of vent shrimp were assigned synonymous genus and species names. Though molecular studies have resolved many of these problems, they are not a panacea because they also suffer from insufficient sampling of taxa and genes, and from contamination of DNA sequences. Working carefully together, molecular and traditional systematists should eventually generate more accurate species lists that allow unbiased estimates of species richness in deep-sea environments.

Phenotypic plasticity or speciation? A case from a clonal marine organism.

BackgroundClonal marine organisms exhibit high levels of morphological variation. Morphological differences may be a response to environmental factors but also they can be attributed to accumulated genetic differences due to disruption of gene flow among populations. In this study, we examined the extensive morphological variation (of 14 characters) in natural populations observed in the gorgonian Eunicea flexuosa, a widely distributed Caribbean octocoral. Eco-phenotypic and genetic effects were evaluated by reciprocal transplants of colonies inhabiting opposite ends of the depth gradient and analysis of population genetics of mitochondrial and nuclear genes, respectively.ResultsSignificant differences (P < 0.001) in 14 morphological traits were found among colonies inhabiting 12 locations distributed in seven reefs in southwest Puerto Rico. Results from principal component analysis indicated the presence of two groups based on depth distribution, suggesting the presence of two discrete morphotypes (i.e. shallow type < 5 m and deep type > 17 m). A discriminant function analysis based on a priori univariate and multivariate analyses (which separated the colonies in morphotypes) correctly classified 93% of the colonies for each environment. Light, water motion and sediment transport might influence the distribution of the two morphotypes. Reaction norms of morphological characters of colonies reciprocally transplanted showed gradual significant changes through the 15 months of transplantation. Sclerites of shallow water colonies became larger when transplanted to deeper environments and vice versa, but neither of the two transplanted groups overlapped with the residents' morphology. Genetic analysis of mitochondrial and nuclear genes suggested that such discrete morphology and non-overlapping phenotypic plasticity is correlated with the presence of two independent evolutionary lineages. The distribution of the lineages is non-random and may be related to adaptational responses of each lineage to the environmental demands of each habitat.ConclusionThe extensive distribution and ample morphological variation of Eunicea flexuosa corresponds to two distinct genetic lineages with narrower distributions and more rigid phenotypic plasticity than the original description. The accepted description sensu Bayer (1961) of E. flexuosa is a complex of at least two distinct genetic lineages, adapted to different habitats and do not exchange genetic material despite living in sympatry. The present study highlights the importance of correctly defining species, because the unknowingly use of species complexes can overestimate geographical distribution, population abundance, and physiological tolerance.

Identity of larval Meristogenys from a single stream in Sabah, Malaysia (Amphibia: Ranidae)

A morphological and molecular survey was conducted to examine the association between larvae and adults of Bornean torrent frog Meristogenys from a stream in Mahua, Crocker Range, Sabah, Malaysia. We identified five discrete morphotypes of larvae, which also showed considerable genetic differentiation. Each larval morphotype was associated through DNA sequence comparisons with adult specimens that had been identified morphologically. One morphotype, identified as M. orphnocnemis, was less similar to the larva of this species than to an unidentified larva, both reported previously. Adults of two other larvae were identified as M. amoropalamus and M. kinabaluensis, but the larval morphotypes differed from previous descriptions of these larvae. Adults associated with another morphotype resembled M. whiteheadi, but had longer tibia. This larval morphotype was dissimilar to previous descriptions of the M. whiteheadi larva, but was similar to another unidentified larva previously reported. No adult specimens were associated with the fifth larval morphotype, which matched the larva reported as M. amoropalamus. From these results, we suspect that either some previous studies include misidentifications or several undescribed, cryptic taxa morphologically resemble known adult species, but differ as larvae.© 2007 The Linnean Society of London, Zoological Journal of the Linnean Society, 2007, 151, 173-189. © 2007 The Linnean Society of London.

Variation among Australian accessions of Vigna vexillata for traits of agronomic, adaptive, or taxonomic interest

Variation among 79 accessions of Vigna vexillata was evaluated for a range of traits of potential agronomic, taxonomic, or adaptive significance, using potted plants grown in the glasshouse over summer. There was significant variation among accessions for all of the traits evaluated except for tuber morphology. The nature and extent of variation are likely to be of agronomic interest in a plant improvement context. Variation among accessions for quantitatively inherited traits relating to phenology, biomass accumulation (vegetative growth, seeds, and tubers), and pod and seed traits was, in most instances, normally distributed, with no evidence of large discontinuities in response. There was evidence of photoperiodic adaptation among accessions from different latitudes and some interrelations between quantitative traits, for which there were usually plausible physiological explanations. Among the several qualitative traits evaluated, there was evidence of minor linkages between some alleles. There was no evidence of major discontinuities in the observed variation, and no evidence of aggregations of traits into distinctive or geographically discrete morphotypes. It is concluded that V. vexillata is relatively homogeneous across the wide geographical range over which it occurs within Australia.

Small theropod and bird teeth from the late Cretaceous (late Campanian) Judith River Group, Alberta

A collection of over 1,700 small theropod teeth from the Judith River Group (Campanian;˜79.5–74 Ma) allows our understanding of the diversity and variation of small theropods in this assemblage to be refined. In addition to the previously recognized taxa, a series of morphologically distinct groups are recognized that may represent distinct taxa in some cases. Teeth with the Paronychodon-like features of a flat surface with longitudinal ridges on one side are resolved into a few discrete morphotypes. Two of these are included in Paronychodon lacustris and two additional morphotypes are hypothesized to represent distinct taxa, here referred to as ?Dromaeosaurus morphotype A and Genus and species indet. A. The teeth of Paronychodon lacustris and ?Dromaeosaurus morphotype A share a distinctive wear pattern that suggests tooth functioning involved contact between the flat surfaces of opposing teeth. Two species of Richardoestesia, R. gilmorei and R. isosceles, are present in the assemblage. Additionally, bird teeth are identified in the assemblage and are described in this review.Bivariate plots were used to document the variation in the theropod teeth, especially in the features that distinguish between Richardoestesia gilmorei, R. isosceles, Saurornitholestes, and Dromaeosaurus. Considerable overlap is present in all plots, so although the teeth are morphologically distinct, they are not easily distinguished by quantitative means.

SMALL THEROPOD AND BIRD TEETH FROM THE LATE CRETACEOUS (LATE CAMPANIAN) JUDITH RIVER GROUP, ALBERTA

Abstract A collection of over 1,700 small theropod teeth from the Judith River Group (Campanian; ∼79.5–74 Ma) allows our understanding of the diversity and variation of small theropods in this assemblage to be refined. In addition to the previously recognized taxa, a series of morphologically distinct groups are recognized that may represent distinct taxa in some cases. Teeth with the Paronychodon-like features of a flat surface with longitudinal ridges on one side are resolved into a few discrete morphotypes. Two of these are included in Paronychodon lacustris and two additional morphotypes are hypothesized to represent distinct taxa, here referred to as ?Dromaeosaurus morphotype A and Genus and species indet. A. The teeth of Paronychodon lacustris and ?Dromaeosaurus morphotype A share a distinctive wear pattern that suggests tooth functioning involved contact between the flat surfaces of opposing teeth. Two species of Richardoestesia, R. gilmorei and R. isosceles, are present in the assemblage. Addition...

Hystricurid trilobite larvae from the Garden City Formation (Lower Ordovician) of Idaho and their phylogenetic implications

Hystricurids are considered to constitute the earliest (early Ibexian or Tremadocian) family of Proetida, based on comparisons of hystricurid larvae with younger proetide and Cambrian ptychopariide larvae. The hystricurid larvae share a fusiform glabella falling short of the anterior margin with other proetide larvae, which were derived from Cambrian ptychopariide larvae with a forward-expanding glabella. Two discrete morphotypes of hystricurid larvae are recognized. The first type is characterized by the development of a pattern of regularly distributed tubercles on the shield and the presence of a preglabellar field. The second is characterized by the presence of glabellar furrows (discontinuous or transglabellar), an indented posterior margin, and a lack of tuberculation. Each of these hystricurid lineages represented by a distinct larval morphotype is considered ancestral (or sistergroup) to a different group of younger proetides. The second larval morphotype is considered a phylogenetic intermediate between the first type and ptychopariide larvae. Several larval features of these primitive proetides are considered to have originated by early onset of post-larval features of the ptychopariides (peramorphic pattern).Newly described hystricurid species areHystricurusn. sp. A,Hystricurus? sp. A,Hystricurus? sp. B, ‘Paraplethopeltis’ n. sp. A, ‘Paraplethopeltis’ sp. B, andHyperbolochiluscf.marginauctum.

Taxonomic study of the IberianCobitis(Osteichthyes, Cobitidae), with description of a new species

Morphometric and electrophoretic variation are analysed among Iberian and African populations ofCobitis(Cobitidae). Three discrete morphotypes are distinguished, showing a remarkable genetic differentiation among them. Each of the three morphotypes is judged to represent a species, one being described as a new species. Both approaches agree on the separate status of the Iberian populations from the Alagón drainage, Tagus basin of west central Spain. This population is described as a new species,Cobitis vettonicasp. nov., a sexually dimorphic spined loach was assigned to the subgenusIberocobitisBacescu, 1961. Morphometric and electrophoretic data placed this new species phenetically close toCobitis maroccanaPellegrin, 1929 andCobitis paludicaDe Buen, 1930, but differs from these species in overall shape, male coloration pattern, shorter barbels and fins, posterior lamina of the cleithrum, seven branched rays on the dorsal fin and in having a unique alleles atsAAT-2*, EST-1*andMPI*loci. The new species range described in this paper is more restricted than that ofC. paludica. Both inhabit the Tagus basin but have not been reported to be sympatric.

Taxonomic study of the Iberian Cobitis (Osteichthyes, Cobitidae), with description of a new species

Abstract Morphometric and electrophoretic variation are analysed among Iberian and African populations ofCobitis(Cobitidae). Three discrete morphotypes are distinguished, showing a remarkable genetic differentiation among them. Each of the three morphotypes is judged to represent a species, one being described as a new species. Both approaches agree on the separate status of the Iberian populations from the Alagon drainage, Tagus basin of west central Spain. This population is described as a new species,Cobitis vettonicasp. nov., a sexually dimorphic spined loach was assigned to the subgenusIberocobitisBacescu, 1961. Morphometric and electrophoretic data placed this new species phenetically close toCobitis maroccanaPellegrin, 1929 andCobitis paludicaDe Buen, 1930, but differs from these species in overall shape, male coloration pattern, shorter barbels and fins, posterior lamina of the cleithrum, seven branched rays on the dorsal fin and in having a unique alleles atsAAT-2*, EST-1*andMPI*loci. The new species range described in this paper is more restricted than that ofC. paludica. Both inhabit the Tagus basin but have not been reported to be sympatric.