An impact assessment of the alien lizard Plestiodon japonicus (Scincidae, Reptilia) on a threatened island population of the native lizard P. latiscutatus at an early phase of the biological invasion

On the island of Hachijojima, central Japan, a formerly abundant population of native lizard, Plestiodon latiscutatus has become endangered by predation from an alien weasel (Mustela itatsi). Recently, an alien lizard, P. japonicus, became established on the island. The impact of the alien lizard and current distribution of the native lizard were assessed by field surveys and DNA analyses. The native lizard was sparsely distributed in the western part of the island. The alien lizard occurred in the northeastern region of the island. Between these regions, several hybrid populations were identified, including some with non-F1 genotypes, suggesting that introgression is occurring. The distribution of the weasel was examined based on field observations, allowing us to estimate predator impacts on both lizard species. We found evidence that the weasel was present throughout the entire island, suggesting that the alien lizard was able to become established despite the presence of the weasel. This indicates that the alien lizard is likely to expand its habitat range and that introgression may spread. We conclude that P. latiscutatus populations will become increasingly endangered by the synergism of genetic introgression from P. japonicus and predation pressure from the weasel.     

Genetic variation and differentiation in the Japanese five-lined skink,Eumeces latiscutatus (Reptilia: Squamata)

The genetic variation in Eumeces latiscutatus from the main islands of Japan and the northern Ryukyus was investigated and compared with that of its close relatives (E. okadae and E. marginatus) using allozyme data. All three samples from the northern Tokara Island Group, currently identified as E. latiscutatus, were shown to belong to E. marginatus and not to E. latiscutatus. The non-monophyly of the northern Tokara samples and the great genetic differences within these samples may have resulted from colonization from more than one source population by northeastward overseas dispersal. The samples from the Izu Peninsula were genetically much closer to E. okadae than the other conspecific ones. This indicates that the samples from the Izu Peninsula and the other samples of E. latiscutatus should be treated as distinct species, and that E. latiscutatus from the Izu Peninsula and E. okadae from the Izu Island Group may be treated as conspecific. Samples from western Japan were genetically well differentiated from those of eastern Japan. Within the western group, the samples from the Osumi Island Group was genetically distinct from those from the other regions, by possessing unique alleles. Our phenograms also reveal a distant affinity between samples from the Danjo Island Group and the main islands of Japan. This may be the result of long geographic isolation of the Osumi and Danjo Island Groups from Kyushu. By contrast, samples from Sapporo and Aomori were poorly differentiated genetically in spite of the long separation of these two localities by the Tsugaru Strait. This suggests that overseas dispersal of E. latiscutatus occurred across this strait after its formation.     

Carpus and tarsus patterns in some Arabian lizards (Reptilia: Agamidae, Lacertidae, Scincidae)

Within the families Agamidae, Lacertidae and Scincidae, the carpal and tarsal elements, the sesamoidea and the ossification pattern show considerable variability. Furthermore, carpal and tarsal structure in the lizards studied here is not unique to the genera in question and identical or very similar conditions occur in other lizards. These elements contain sufficient anatomical information to make them taxonomically valuable.     

Ultrastructure of the dermal chromatophores in a lizard (Scincidae: Plestiodon latiscutatus) with conspicuous body and tail coloration

Microscopic observation of the skin of Plestiodon lizards, which have body stripes and blue tail coloration, identified epidermal melanophores and three types of dermal chromatophores: xanthophores, iridophores, and melanophores. There was a vertical combination of these pigment cells, with xanthophores in the uppermost layer, iridophores in the intermediate layer, and melanophores in the basal layer, which varied according to the skin coloration. Skin with yellowish-white or brown coloration had an identical vertical order of xanthophores, iridophores, and melanophores, but yellowish-white skin had a thicker layer of iridophores and a thinner layer of melanophores than did brown skin. The thickness of the iridophore layer was proportional to the number of reflecting platelets within each iridophore. Skin showing green coloration also had three layers of dermal chromatophores, but the vertical order of xanthophores and iridophores was frequently reversed. Skin showing blue color had iridophores above the melanophores. In addition, the thickness of reflecting platelets in the blue tail was less than in yellowish-white or brown areas of the body. Skin with black coloration had only melanophores.     

Three genetic lineages of the Japanese skink Plestiodon japonicus (Scincidae, Squamata) and the genetic composition of their contact zones

Geographic differentiation of the Japanese skink ( Plestiodon japonicus ) throughout the entire Japanese main islands was surveyed using two DNA markers, mitochondrial DNA (mtDNA) and an internal transcribed spacer of nuclear ribosomal genes (ITS-1). Both of the markers concordantly demonstrated geographically discontinuous differentiation between three genetic lineages: the northeastern, central and western lineages. Little to no gene flow occurs between the western and central lineages despite their parapatric distribution suggesting an existence of reproductive isolation despite no known morphological and ecological dissimilarities. On the other hand, the geographic ranges of the northeastern and central lineages are partially separated by a wide area occupied by genetically intermediate type having northeastern mtDNA and central ITS-1. The current data imply that the intermediate type was established by past secondary hybridization between the northeastern and central lineages. Although current gene flow status between the northeastern and central lineages should be elaborated by further data, at least the divergence between the central and western lineages should be maintained by reproductive isolation and therefore taxonomic revision of the species is desired.     

Temporal change in nutrient concentrations and phytoplankton biomass in short time scale local upwelling around the Izu Peninsula, Japan*

Temporal changes in nitrate plus nitrite and chlorophyll concentrationswere observed by continuous shipboard measurements in upwelledand coastal water masses covering an area 20 x 30 km² alongthe Izu Peninsula between May 22 and 26, 1982. Two localizedupwelling events were observed, one which had occurred beforeMay 22 and the other on May 26. Nutrient input into the surfacefrom upwelling and subsequent phytoplankton growth were clearlydocumented. Phytoplankton growth, estimated from the disappearanceof nutrients, agreed well with modelling estimates based uponsimulated culture experiments done previously in the same area.Phytoplankton growth terminated when nutrients were depleted.Similar stimulation of phytoplankton growth supported by localizedupwelling can be expected in other coastal regions where similarconditions exist.     

Systematics of limbless scincid lizards from northern Madagascar: morphology,phylogenetic relationships and implications for classification (Squamata: Scincidae)

We report on the rediscovery of two limbless scincid species, Paracontias rothschildi Mocquard, 1905 and Paracontias minimus (Mocquard, 1906), after more than a century. The two species were found in syntopy in sandy soils of Forêt d’Orangea, Antsiranana Province, northern Madagascar, which probably constitutes the respective type locality and confirms the species’ Malagasy origin. Both taxa are redescribed based on newly collected material, and compared to other Malagasy species. In addition, Paracontias fasika n. sp. is described from the same locality and habitat. We discuss the taxonomy and origin of all three species and provide preliminary data on their natural history. Molecular relationships among seven Paracontias species are compared to external morphological characters formerly used in skink systematics. Our results indicate that morphology in fossorial skinks is well suited to distinguish species, but is of rather limited value to elucidate phylogenetic relationships. Similarities between these skinks in external characters apparently are the result of convergent evolution due to parallel selective pressures.     

The Ultrastructure of the Spermatozoa of Squamata—I. Scincidae,Gekkonidae and Pygopodidae (Reptilia)

Abstract Squamate autapomorphies seen in sperm of the Scincidae (e.g. Ctenotus robustus, Carlia pectoralis, Cryptoblepharus virgatus, and Lampropholis delicata) are penetration of the fibrous sheath of the axoneme into the midpiece, and the paracrystalline subacrosomal cone. Sphenomorphus group spermatozoa (e.g. Ctenotus) and the Egernia group (Tiliqua) differ from the more derived Eugongylus group (C. virgatus, L. delicata and C. pectoralis) in that the acrosome is elongate and apically depressed; the perforatorium is strongly oblique; the midpiece is relatively short, with four dense ring structures in longitudinal succession; mitochondria are columnar; and enlarged peripheral fibres 3 and 8 do not show the gross anterior enlargement seen in Carlia and Lampropholis. Heteronotia binoei (Gekkonidae) sperm have no epinuclear electron-lucent region; nuclear shoulders are smooth, as in sphenomorph but not Eugongylus group skinks; mitochondria are columnar; unlike skinks, the median surfaces of the mitochondria are indented by triangular, sometimes longitudinally, interconnected dense bodies. In Lialis burtonis (Pygopodidae) sperm, the perforatorium extends virtually to the tip of the fore-shortened apically domed acrosome; nuclear shoulders are absent; the mitochondria alternate singly or in groups with one or more dense bodies which also form an interrupted collar around the distal centriole. Spermatozoal ultrastructure suggests that a common ancestry of snakes and pygopods deserves consideration.     

Ontogeny of hemopoietic and lymphopoietic tissues in the lizard Chalcides ocellatus (Reptilia,Sauna, Scincidae)

The first and major blood-forming organ to develop in the viviparous lizard Chalcides ocellatus is the yolk sac, which exhibits prominent erythropoietic activity from as early as stage 21 through birth (stage 41). Myeloid cells and megakaryocytes are produced in the yolk sac from stage 23 onward. During lizard embryogenesis hemopoietic activity is also observed in spleen and bone marrow but in neither kidney nor liver. Cells capable of giving rise to lymphocytes both in vivo and in vitro are first found in the thymus at stage 35. Active lymphopolesis in thymus and spleen begins at stages 36 and 39, respectively. In contrast, the gut-associated lymphoid aggregates are not evident before birth.     

Parallel gigantism and complex colonization patterns in the Cape Verde scincid lizards Mabuya and Macroscincus (Reptilia: Scincidae) revealed by mitochondrial DNA sequences

The scincid lizards of the Cape Verde islands comprise the extinct endemic giant Macroscincus coctei and at least five species of Mabuya, one of which, Mabuya vaillanti, also had populations with large body size. Phylogenetic analysis based on DNA sequences derived from the mitochondrial cytochrome b, cytochrome oxidase I and 12S rRNA genes (711, 498 and 378 base pairs (bp), respectively) corroborates morphological evidence that these species constitute a clade and that Macroscincus is unrelated to very large skinks in other areas. The relationships are ((M. vaillanti and Mabuya delalandii) (Mabuya spinalis and Macroscincus coctei (Mabuya fogoensis nicolauensis (Mabuya fogoensis antaoensis and Mabuya stangeri)))). The Cape Verde archipelago was colonized from West Africa, probably in the Late Miocene or Early Pliocene period. The north-eastern islands were probably occupied first, after which the ancestor of M. vaillanti and M. delalandii may have originated on Boavista, the ancestor of the latter species arriving on Santiago or Fogo later. The M. fogoensis--M. stangeri clade colonized the islands of Branco, Razo, Santa Luzia and São Vicente from São Nicolau and reached Santo Antão after this. Colonization of these northeastern islands was slow, perhaps because the recipient islands had not developed earlier or because colonization cut across the path of the Canary Current and the Northeast Trade Winds, the main dispersing agents in the region. Rapid extension of range into the southwestern islands occurred later in M. spinalis and then in M. vaillanti and M. delalandii. The long apparent delay between the origin of these species and their southwestern dispersal may have been because there were earlier colonizations of the southern islands which excluded later ones until the earlier inhabitants were exterminated by volcanic or climatic events. The evolution of large size in Macroscincus occurred in the northwestern islands and was paralleled in the eastern and southern islands by populations of M. vaillanti. Both cases of size increase in Cape Verde skinks were accompanied by the development of herbivory.     

The karyotypes of two scincid lizards,and their bearing on relationships in genus Leiolopisma and its relatives (Scincidae: Lygosominae)

Abstract

The karyotypes of the skinks Leiolopisma telfairi (Desjardin) and Cyclodina oliveri (McCann) are presented for the first time, from male spceimens. Metaphase cells from intestinal epithelium (C. oliveri) and testicular material (C. oliveri and L. telfairi) gave the diploid number, 2n = 30, for both species. Heteromorphism of the pair 6 chromosomes was observed in C. oliveri; this is the first published report of male heterogamety in the Scincidae. A common origin is proposed for L. spenceri and L. telfairi, on the basis of chromosome pair 8 morphology. These species may be more closely allied to Cyclodina than previously believed.     

Relationships of lacertid lizards (Reptilia: Lacertidae) estimated from mitochondrial DNA sequences and morphology.

DNA sequences from parts of the 12S, 16S and cytochrome b mitochondrial genes, which totalled 1049 aligned base pairs, were used to estimate the relationships of 49 species of Lacertidae, including representatives of 19 out of the 23 recognized genera and 23 species of the paraphyletic genus Lacerta. These data were used, together with morphological information, to estimate the relationships within the family. Molecular evidence corroborates the monophyletic status of many genera and species groups originally based on morphology. It indicates that Psammodromus forms a clade with Gallotia, which is the sister taxon of all other lacertids. These comprise three units: the primarily Afrotropical armatured group; the largely Oriental Takydromus; and the west Palaearctic Lacerta and its derivatives, Podarcis and Algyroides. Morphology also supports the first three assemblages, but suggests that they are derived from a paraphyletic Lacerta. Within Lacerta and its allies, DNA sequence analysis corroborates the affinity of some members of each of the subgenera Lacerta s. str. and Timon, and of the L. saxicola group. It also supports the relationship of L. monticola, L. bonnali and L. horvathi, and suggests that the L. parva--L. fraasi clade and L. brandli are not related to Psammodromus Gallotia, as morphology indicates, but instead are associated respectively with the L. danfordi and L. saxicola groups. DNA sequence data provide additional evidence that the eastern Arabian ''Lacerta'' jayakari and ''L.'' cyanura are members of the armatured clade and also sister species. Our analysis supports an origin for present lacertids in west Eurasia. The armatured clade invaded Africa, probably in the mid-Miocene, spreading widely and evolving increasingly xeric-adapted forms, one lineage of which later moved back into the Palaearctic. ''Lacerta'' jayakari and ''L.'' cyanura are assigned to Omanosaura, Lutz and Mayer 1986. The name Gallotiinae Cano, Baez, Lopez-Jurado & Ortega, 1984 is available for the Gallotia-Psammodromus clade, Eremiainae Shcherbak 1975 for the armatured clade and Lacertinae for Lacerta, Podarcis and Algyroides. Two new subgenera of Lacerta are proposed here: Caucasilacerta for L. saxicola and its allies, and Parvilacerta for L. parva and L. fraasi.     

Phylogenetic relationships, character evolution, and biogeography of the subfamily Lygosominae (Reptilia: Scincidae) inferred from mitochondrial DNA sequences

Phylogenetic relationships among the lygosomine skinks were inferred from 1249 base positions of mitochondrial DNA sequences of 12S and 16S rRNA genes. The monophyly of this subfamily was confirmed and the presence of five distinct infrasubfamilial lineages detected. Of these, the Sphenomorphus group appears to have diverged first, followed by the Lygosoma and Egernia groups in order, leaving the Eugongylus and Mabuya groups as sister groups. Our results did not support monophyly of the Mabuya group sensu lato (i.e., an assemblage of the Lygosoma, Egernia, and Mabuya groups), for which a number of morphological and karyological studies demonstrated a considerable similarity. Our results also contradict the previous hypothesis, formulated on the basis of morphological and immunological data, which argued for the sister relationship between the Egernia and the Eugongylus groups. Morphological and karyological characters used to define the Mabuya group (sensu lato) may actually represent plesiomorphic states. The phylogenetic diversity of lygosomine skinks in the Australian region appears to have increased through multiple colonizations from Southeast Asia.     

The m. caudifemoralis longus and its relationship to caudal autotomy and locomotion in lizards (Reptilia: Sauna)

Although the phenomenon of tail autotomy has traditionally been viewed in a purely adaptive light, functional constraints imposed by the locomotor system appear to have influenced the presence and extent of autotomy in lizards. Them. caudifemoralis longus is an unsegmented hind limb retractor that originates from the caudal vertebrae. It does not participate in autotomy and thus limits the proximal position of autotomic septa. Variation in the extent of the m. caudifemoralis is correlated with locomotor type. The muscle is large and originates from a long series of caudal vertebrae in fast moving lizards with powerful limb retraction, as exemplified by taxa capable of bipedal running. In slower lizards with sprawling postures, such as geckos, the m. caudifemoralis is small and restricted to the first few postsacral vertebrae. Autotomy is typically restricted or absent in the former lizards, while in the latter only the most proximal vertebrae are incapable of autotomy. In the evolution of existing patterns of caudal autotomy, functional demands intrinsic to the tail may be subservient to locomotor constraints imposed on the tail base by the m. caudifemoralis longus .     

Postembryonic development of the sea spider Ammothella biunguiculata (Pycnogonida,Ammotheidae) endoparasitic to an actinian Entacmaea quadricolor (Anthozoa,Stichodactylidae) in Izu Peninsula,Japan

Postembryonic developmental stages of an endoparasitic pycnogonid, Ammothella biunguiculata in Izu Peninsula, Japan are described. Eleven stages were identified beginning with a protonymphon larva attached to the male oviger. We found endoparasitic individuals in the host actinian from the second to tenth instar, and forms in the ninth stage to adult were found free-living. This indicates a transition from being endoparasitic to free-living during the ninth to tenth instar stages. The first instar protonymphon attached to the adult male oviger has a gland duct on the anterior margin of each chelifore scape which completely disappears with the second instar. The disappearance of the chelifore gland duct coincides with the beginning of an endoparasitic stage in the development of this species. Although the larval morphology and the postembryonic development of pycnogonids have been summarized by several authors, the present study concludes that much remains to be learnt.     

Comparative phylogeography of three skink species (Oligosoma moco, O. smithi, O. suteri; Reptilia: Scincidae) in northeastern New Zealand

Sea-level fluctuations during the Pliocene and Pleistocene have shaped the landscape of the Northland region of New Zealand. We examined the comparative phylogeography of three skink species (Oligosoma moco, O. smithi, O. suteri) in northeastern New Zealand in order to investigate the impact of the historical processes that have prevailed since the Pliocene on the Northland fauna. O. moco, O. smithi and O. suteri have similar distributions across northeastern New Zealand, frequently occurring in sympatry. We obtained sequence data from across the entire range of each species, targeting the ND2 mitochondrial gene. Using Neighbor-Joining, Maximum likelihood and Bayesian methods, our analysis revealed contrasting phylogeographic patterns in each species. We found substantial phylogeographic structure within O. moco, with three distinct clades identified. Similarly, deep phylogeographic divergence was evident within O. smithi, with three distinct clades present. Clade 1 included O. smithi populations from the Three Kings Islands and the western coastline of Northland, while Clade 2 encompassed the remainder of the range. However, since Clade 3 corresponded to a described species (O. microlepis), O. smithi might represent a species complex. In both O. moco and O. smithi, divergences among clades are estimated to have occurred in the Pliocene, with divergences within clades occurring during the Pleistocene. In contrast, genetic divergence among O. suteri populations was extremely limited and indicative of more recent divergences during the Pleistocene. The lack of phylogeographic structure in O. suteri might be a consequence of its oviparous reproductive mode, which restricted its distribution to warm northern refugia during glacial maxima. Differences in the ecology and biology of each species might have produced contrasting responses to the same historical processes, and ultimately diverse phylogeographic patterns. Our study reveals an absence of consistent and concordant phylogeographic patterns in the Northland biota, even within the same taxonomic group.     

Dewlap and other variation in the lizards Anolis distichus and A. brevirostris (Reptilia: Iguanidae)

The dewlap of male anoline lizards is an important component of the mate recognition system. Much attention has focussed on the role dewlap colour plays in the interactions between species of Anolis but little has been paid to the effects of intraspecific variability in this feature. Patterns of intrasubspecific variability in this feature are described for several subspecies of Anolis distichus and A. brevirostris . In most cases variability in dewlap colour appears unrelated to the amount of electrophoretic variability and the level of population differentiation, although there is some evidence for large scale geographic subdivision within three of the taxa examined. Female choice and the implications for various species concepts are discussed.