The structure and development of the digital lamellae of lizards

The epidermal setae and the spinules of the digital lamellae of anoline and gekkonid lizards are shed periodically along with the rest of the outer layer of the skin. These structures are developed within the lamellae prior to ecdysis. The setae are larger and more complicated than the spinules and begin their development first. The setae of Anolis start as aggregations of tonofibrils beneath the plasma membrane of the presumptive Oberhautchen cells. These cells are arranged in rows parallel to the surface, several cell layers beneath the alpha layer of the skin. The developing setae protrude into the clear layer cells as finger-like projections, with the tonofibrils longitudinally oriented in the direction of growth. About 100 setae are formed by each Oberhautchen cells in Anolis. In late development, the clear layer cells lose their cellular contents and when shed along with all distal cells, retain a template of the new setae or spinules. The spinules and setae are formed before the fibrous and alpha layers of the new skin. The fibrous layer, which occurs only on the ventral (outer) layer of the lamellae, and the Oberhautchen with its setae and spinules, is considered the beta layer. The alpha layer, which occurs adjacent to the fibrous layer on the ventral surface and adjacent to the Oberhautchen on the dorsal (inner) surface, is morphologically identical to that of mammalian α keratin. The shed lizard skin consists of the alpha and beta layers as well as the degenerating cells of the outer epidermal generation, and the clear layer. The clear layer that is shed shows the template of the new setae and spinules developed in the new skin layer. The separation of the new from the old skin occurs along the intercellular space between the clear layer cells and the new Oberhautchen. The alpha layer of the skin is not fully keratinized at shedding. The setae of the digital lamellae of lizards represent unique epidermal structures — intracellular keratinized microstructures.     

Surface structure and frictional properties of the skin of the Amazon tree boa <Emphasis Type="Italic">Corallus hortulanus</Emphasis> (Squamata,Boidae)

The legless locomotion of snakes requires specific adaptations of their ventral scales to maintain friction force in different directions. The skin microornamentation of the snake Corallus hortulanus was studied by means of scanning electron microscopy and the friction properties of the skin were tested on substrates of different roughness. Skin samples from various parts of the body (dorsal, lateral, ventral) were compared. Dorsal and lateral scales showed similar, net-like microornamentation and similar friction coefficients. Average friction coefficients for dorsal and lateral scales on the epoxy resin surfaces were 0.331 and 0.323, respectively. In contrast, ventral scales possess ridges running parallel to the longitudinal body axis. They demonstrated a significantly lower friction coefficient compared to both dorsal and lateral scales (0.191 on average). In addition, ventral scales showed frictional anisotropy comparing longitudinal and perpendicular direction of the ridges. This study clearly demonstrates that different skin microstructure is responsible for different frictional properties in different body regions.     

High genetic diversity among fossorial lizard populations (Anniella pulchra) in a rapidly developing landscape (Central California)

California is a biodiversity hotspot facing unbridled human population growth, especially in Central California. One of the poorly known, sensitive species in this area is the California legless lizard (Anniella pulchra), a fossorial worm-like reptile. We report mt and nuDNA sequences from 69 museum-vouchered samples of Anniella (A. pulchra and its sister species A. geronimensis) from 48 localities. Our genetic survey reveals substantially more genetic diversity within A. pulchra than previously reported. Our two independently evolving markers (mt and nuDNA) reveal five major lineages of A. pulchra. Two of the five major lineages of A. pulchra correspond to a north-south split found in other widespread California reptiles. These northern and southern clades also correspond to a previous study showing variation in chromosomal number. Unlike most other Californian reptiles, A. pulchra has major genetic lineages that are endemic to Central California including two that are endemic to the San Joaquin Valley and Carrizo Plain. Although A. pulchra is threatened throughout its range, the distinct San Joaquin lineages are seriously imperiled by urban sprawl. Some of the localities for the newly recognized genetic lineages have already been destroyed by development.     

有鳞目动物鳞片表面超微结构的适应性进化

爬行动物鳞片的微结构是对环境的一种适应。本研究运用扫描电子显微镜观察了北草蜥(Takydromus septentrionalis)、脆蛇蜥(Dopasia harti)和王锦蛇(Elaphe carinata)头部、背部和腹部鳞片的微皮纹结构及感受器特征。结果表明,3个物种的微皮纹和感受器存在种间差异。北草蜥和王锦蛇背部及腹部微皮纹均为狭长带状,脆蛇蜥为不规则多边形。北草蜥和王锦蛇颔片上有感受器,北草蜥无。脆蛇蜥腹部微皮纹上无小齿状凸起,北草蜥和王锦蛇有,与北草蜥相比王锦蛇的小齿状凸起更宽更长。王锦蛇的眼部微皮纹为向上竖起的脊,而其他部位的鳞片为具有小齿状凸起的狭长带状结构。本研究共收集整理17科99种的背鳞微皮纹数据和8科25种的感受器数据,对微皮纹特征和感受器形态进行祖先重建发现,狭长带状背鳞微皮纹主要存在于蜥蜴科(Lacertidae)、游蛇科(Colubridae)和石龙子科(Scincidae)中,而鬛蜥科(Agamidae)、蛇蜥科(Anguidae)、蟒蛇科(Boidae)以及蝰蛇科(Viperidae)的大多为多边形;较原始的感受器形态为无感觉毛的透镜状,这一结构在有鳞目动物进化中发生多次演化。本研究发现蛇蜥的鳞片表面微结构更接近于蛇类动物。因此,有鳞类动物鳞片微皮纹特征和皮肤感受器的形态是对其所处环境多重压力的优化选择。     

东方沙蟒显微皮纹结构与功能

对隶属蟒科的东方沙蟒唇鳞的光学显微结构和扫描电镜下的超微结构的观察发现了类似小窝的结构,可能是原始的鳞片感受器官;对鳞片感受器的大小做了测量;同时观察了头部其他鳞片和身体中部背鳞和腹鳞的显微皮纹结构。所有鳞片的角皮层细胞平坦,没有大的表面特征结构,除了后缘齿状结构、微孔和窄而短的边界。考虑到穴居种类减少反光不是主要的选择因子,而主要选择是减少摩擦和清除污物,显微皮纹特征很好地符合这一假说。不同部位鳞片的差异主要表现在角皮层细胞的形状和的大小,微孔的有无,细胞后缘齿状结构的有无和大小以及细胞边界重叠的程度。首次描述了鹅卵石样多孔细胞这一微饰类型。     

Histological changes in the epidermis of the subdigital lamellae of Anolis carolinensis during the shedding cycle

The characteristic anoline climbing organ consists of a number of lamellar scales, on whose outer scale surface are numerous keratinized setae which contact the substrate. These setae are derived from the Oberhautchen of the epidermal generation, and as such are renewed and shed periodically along with the rest of the epidermal material. The histological development of the setae is described, and modifications of the surrounding elements are noted. The relative lengths of the setae and their congregation to form a pad unit poses certain mechanical problems during morphogenesis, simply in terms of accommodation between the functional outer epidermal generation and dermal core of each lamella. Regression of the dermal core and a distal migration of some cells permits accommodation within the lamella for the distal aspect of the Oberhautchen layer, or free margin. Additionally, changes in the gross shape of the lamella occur throughout the sloughing cycle, and a swelling of the cells of the lacunar tissue results in a gap between the stratum corneum of inner and outer epidermal generations. There is a considerable amount of variation in mitotic activity between the germinal layers of opposite sides of the lamella.     

SALMFamide2 and serotonin immunoreactivity in the nervous system of some acoels (Xenacoelomorpha)

Acoel worms are simple, often microscopic animals with direct development, a multiciliated epidermis, a statocyst, and a digestive parenchyma instead of a gut epithelium. Morphological characters of acoels have been notoriously difficult to interpret due to their relative scarcity. The nervous system is one of the most accessible and widely used comparative features in acoels, which have a so‐called commissural brain without capsule and several major longitudinal neurite bundles. Here, we use the selective binding properties of a neuropeptide antibody raised in echinoderms (SALMFamide2, or S2), and a commercial antibody against serotonin (5‐HT) to provide additional characters of the acoel nervous system. We have prepared whole‐mount immunofluorescent stainings of three acoel species: Symsagittifera psammophila (Convolutidae), Aphanostoma pisae, and the model acoel Isodiametra pulchra (both Isodiametridae). The commissural brain of all three acoels is delimited anteriorly by the ventral anterior commissure, and posteriorly by the dorsal posterior commissure. The dorsal anterior commissure is situated between the ventral anterior commissure and the dorsal posterior commissure, while the statocyst lies between dorsal anterior and dorsal posterior commissure. S2 and serotonin do not co‐localise, and they follow similar patterns to each other within an animal. In particular, S2, but not 5‐HT, stains a prominent commissure posterior to the main (dorsal) posterior commissure. We have for the first time observed a closed posterior loop of the main neurite bundles in S. psammophila for both the amidergic and the serotonergic nervous system. In I. pulchra, the lateral neurite bundles also form a posterior loop in our serotonergic nervous system stainings.     

Scale microornamentation of uropeltid snakes

Microornamentation was examined on the exposed oberhautchen surface of dorsal, lateral, and ventral scales from the midbody region of 20 species of the fossorial snake family Uropeltidae and seven species of fossorial scolecophidian and anilioid outgroups. No substantial variation was observed in microornamentation from the different areas around the midbody circumference within species. All oberhautchen cells were flat and exhibited no major surface features other than occasional posterior margin denticulations, small pores/pits, and narrow, low ridges. This is largely consistent with the hypothesis that friction reduction and dirt shedding are the main selective pressures on microornamentation, given that reducing shine is not of key importance in fossorial animals. Variations among taxa were observed in the shape and size of oberhautchen cells, in the presence of pores/pits, in the presence and size of denticulations on posterior cell margins, and in the level or imbricate nature of cell borders. Six microornamentation characters were formulated, scored, and plotted onto a selected phylogeny. Character evolution and phylogenetic signal were explored, accepting the incomplete understanding of intraspecific variation and of uropeltid interrelationships. There is evidence that all but one of these characters evolved homoplastically, probably by multiple independent origin. There is no clear evidence for character state reversal, but greater phylogenetic resolution is required to test this further. Phylogenetic signal appears to exist in some instances, including possible microornamentation synapomorphies for Uropeltidae and Melanophidium. These derived character states are found elsewhere within Squamata. A microornamentation of narrow, finely, and regularly spaced ridges is associated with scale iridescence. These ridges, and possibly pores/pits, are also associated with scales that are less wettable, and that therefore might be expected to be better at shedding dirt in moist conditions. Testable hypotheses are presented that might explain minor variations in the form of ridges and pits among uropeltids.     

Spermatogenesis and the structure of the testes in Isodiametra pulchra (Isodiametridae,Acoela)

Boone M., Willems M., Claeys M. and Artois, T. 2011. Spermatogenesis and the structure of the testes in Isodiametra pulchra (Isodiametridae, Acoela). —Acta Zoologica (Stockholm) 92 : 101–108. Spermatogenesis and the structure of the testes were studied ultrastructurally in Isodiametra pulchra (Smith and Bush, Transactions of the American Microscopical Society 1991; 110: 12; Hooge and Tyler, Journal of zoological systematics and evolutionary research 2005; 43: 100). The testes are paired, compact, non‐follicular and lie dorsally and dorso‐laterally to the paired ovaries, partially enfolding them. All stages of spermatogenesis, including spermiogenesis, are described at the ultrastructural level and their spatial organization within the testes is discussed. The cells at the early stages of spermatogenesis (spermatogonia and spermatocytes) are located on the dorsal and dorso‐lateral sides of the testes, while the late stages (spermatids and filiform spermatozoa with 9+2 axonemes) lie at the ventral and inner periphery of the testes, adjacent to ovaries. All the cell types can be found both at the anterior and the posterior end of the testes. The value of the structure of the testes as a phylogenetic marker is addressed.     

Histology and lectin-binding patterns in the skin of the terrestrial horned frog Ceratophrys ornata

The terrestrial horned frog, Ceratophrys ornata, lives on a wet substratum and absorbs water through the ventral epidermis; water is lost by evaporation from the dorsal skin. Thus, this species may be useful as a model for determining whether or not skin histology and lectin-binding patterns, indicative of glycoconjugates, are related to skin functions such as osmoregulation and water balance. With this in mind, a histological and lectin-histochemical study was carried out on dorsal and ventral skin of aquatic tadpoles and of a young terrestrial frog of C. ornata. Sections of skin were stained with various dyes to demonstrate general histological features and with two horseradish peroxidase (HRP)-conjugated lectins, Ulex europaeus agglutinin (UEA 1) and soybean agglutinin (SBA) which bind to specific terminal sugar residues of glycoconjugates, namely L-fucose and N-acetyl-D-galactosamine or D-galactose, respectively. In early stage tadpoles both lectin-binding patterns were similar in the bilaminar epidermis of dorsal and ventral skin (i.e., each lectin stained the apical cell layer). However, metamorphic changes resulted in a young frog with typical adult-type skin composed of a stratified squamous epidermis and three distinct types of glands containing glycoconjugates in their secretions. Strikingly different lectin-binding patterns were evident in the epidermis from dorsal and ventral regions of the body. The epidermis from the dorsal region was stained by both lectins; in contrast, that from the ventral region although stained strongly by HRP-SBA, did not react with HRP-UEA 1 indicating that few, if any, fucose residues were present in the ventral epidermis. These findings, as suggested in the discussion, indicate that different glycoconjugate patterns in dorsal and ventral skin may be associated with the regulation of water balance in the frog.     

A new species of sculpin,Icelus ecornis (Scorpaeniformes: Cottidae) from the southwestern Okhotsk Sea

A new cottid species,Icelus ecornis, is described on the basis of 31 specimens collected from 159–226 m in the southwestern Okhotsk Sea off Hokkaido, Japan. It is distinguished from all other members of the genusIcelus by the following combination of characters: no supraocular and parietal spines; short blunt nuchal spine; cirri absent from head and body, except for supraocular, parietal and nuchal regions; platelike scales of dorsal row bearing 6–10 long uniform spinules; tubular lateral line scales bearing small spines on dorsal and posterior margins; large oval black spot on first dorsal fin; 16–20 anal fin rays.     

Convergent evolution of the lateral line system in Apogonidae (Teleostei: Percomorpha) determined from innervation

The lateral line system and its innervation were examined in two species of the family Apogonidae (Cercamia eremia [Apogoninae] and Pseudamia gelatinosa [Pseudamiinae]). Both species were characterized by numerous superficial neuromasts (SNs; total 2,717 in C. eremia; 9,650 in P. gelatinosa), including rows on the dorsal and ventral halves of the trunk, associated with one (in C. eremia) and three (in P. gelatinosa) reduced trunk canals. The pattern of SN innervation clearly demonstrated that the overall pattern of SN distribution had evolved convergently in the two species. In C. eremia, SN rows over the entire trunk were innervated by elongated branches of the dorsal longitudinal collector nerve (DLCN) anteriorly and lateral ramus posteriorly. In P. gelatinosa, the innervation pattern of the DLCN was mirrored on the ventral half of the trunk (ventral longitudinal collector nerve: VLCN). Elongated branches of the DLCN and VLCN innervated SN rows on the dorsal and ventral halves of the trunk, respectively. The reduced trunk canal(s) apparently had no direct relationship with the increase of SNs, because these branches originated deep to the lateral line scales, none innervating canal neuromast (CN) homologues on the surface of the scales. In P. gelatinosa, a CN (or an SN row: CN homologue) occurred on every other one of their small lateral line scales, while congeners (P. hayashii and P. zonata) had an SN row (CN homologue) on every one of their large lateral line scales.     

A systematic study of the pulchra species group of Archips occurring in Japan (Lepidoptera, Tortricidae)

This paper reviews the pulchra species group of Archips, describes a new species, Archips stellata, and redescribes A. pulchra (Butler) and A. abiephaga (Yasuda). Although long confused with each other, these three species are distinguishable by differences in the wing markings, abdominal dorsal pits, and genitalia. To position the pulchra group systematically within the genus Archips, earlier related studies are reviewed and the phylogenetic relevance and polarities of traits are discussed. The forewing pattern, consisting of transverse black and glossy gray fasciae, is presumed to be the only synapomorphy of this group; affinity between the pulchra group and other groups of Archips in some traits may reflect symplesiomorphy.     

Dorsoventral Differences in Cell-Cell Interactions Modulate the Motile Behaviour of Cells from the Xenopus Gastrula

When groups of cells from the inner marginal zone (mesendoderm) of the early Xenopus gastrula are placed on a fibronectin-coated substratum, the explants of the dorsal region spread into monolayers whereas those from the ventral region, though they adhere to the substratum, do not show this spreading reaction. This different behaviour is not reflected in the in vitro behaviour of the respective cells kept in isolation. No difference between dorsal and ventral cells was observed, when they were tested for lamellipodia-driven spreading, movement over the substratum or properties of integrin- and cadherin-mediated adhesion. However, cell contacts between individual dorsal cells are significantly less stable than those between ventral cells. The higher flexibility of the cell-cell contacts seems to determine the spreading behaviour of the dorsal explants, which includes lamellipodia-driven outward movement of the peripheral cells, rearrangements of the cells, building up a horizontal tension within the aggregate and intercalation of cells from above into the bottom layer. Ventral explants lack these properties. Staining for F-actin revealed a decisive difference of the supracellular organisation of the cytoskeleton that underlies the morphology of the different types of explants. Evidence for a higher flexibility of cell-cell contacts in the dorsal mesendoderm was also obtained in SEM studies on gastrulating embryos. Dorsal mesendodermal cells show stronger protrusive activity as compared to ventral mesendodermal cells. The meaning of these observations for the mechanisms of morphogenetic movements during gastrulation is central to the discussion.     

Ultrastructural contributions to the identification of cell types in the lizard epidermal generation

The ultrastructure of the epidermis at different stages of the shedding cycle has been studied in Anolis carolinensis. Cells of the germinal layer are morphologically similar at all stages in the cycle. Immediately after leaving the germinal layer all daughter cells resemble one another closely. However, they later acquire specific ultrastructural features that enable them to be classified into six distinct fully differentiated types corresponding to the grouping previously set forth by light microscopy. A comparison of cytoplasmic filament size with the known X-ray diffraction data suggests that the Oberhautchen and β-layer contain a protein similar to that of avian feather; the protein in the α-layer and lacunar tissue is similar to that in mammalian hair, and the mesos layer cells probably contain a mixture of feather and hair-like proteins. The nature of the amorphous cytoplasmic material in the mature clear layer is as yet unknown.     

Phenotypic evolution in high‐elevation populations of western fence lizards (Sceloporus occidentalis) in the Sierra Nevada Mountains

Adaptive divergence in response to variable habitats, climates, and altitude is often accentuated along elevation gradients. We investigate phenotypic evolution in body size and coloration in the western fence lizard (Sceloporus occidentalis Baird & Girard, 1852) across elevation gradients in Yosemite National Park, California, situated in the Sierra Nevada mountains of Western North America. High‐elevation populations occurring above 2100 m a.s.l. are recognized as a separate subspecies (Sceloporus occidentalis taylori Camp, 1916), with a distinctive phenotype characterized by a large body size and extensive blue ventral pigmentation. We sampled S. occidentalis from across elevation gradients in Yosemite National Park, California, and collected phenotypic data (body size and ventral coloration measurements; 410 specimens) and mitochondrial DNA sequence data (complete NADH1 gene; 969 bp, 181 specimens) to infer phylogenetic relationships, and examine the genetic and phenotypic diversity among populations. Populations of S. occidentalis in Yosemite National Park follow Bergmann's rule and exhibit larger body sizes in colder, high‐elevation environments. The high‐elevation subspecies S. o. taylori is not monophyletic, and the mitochondrial DNA genealogy supports a model of convergent phenotypic evolution among high‐elevation populations belonging to different river drainages. The hypothesis that separate populations of S. occidentalis expanded up river drainages after the recession of glaciers is supported by population demographic analyses, and suggest that Bergmann's clines can evolve rapidly along elevation gradients. The distinctive high‐elevation phenotype that is attributable to S. o. taylori has evolved independently several times, and includes adaptive phenotypic changes associated with increases in body size and ventral coloration. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 630–641.     

Morphology and function of the dorsal sound producing scales in the tail of Teratoscincus scincus (Reptilia; Gekkonidae)

The tail of Teratoscincus scincus has dorsal scales that have tubercles on their dorsal and ventral surfaces. Sounds are produced when these rub past each other as the excited animal moves its tail. The relative movement of scales is intensified by caudal torsion. The frequencies of the sounds cover a range from 9 to 25 kops and thus, differ from those produced during vocalizations.     

A new cottid species, Icelus sekii (Perciformes: Cottoidei), from Hokkaido, Japan

A new cottid species, Icelus sekii, is described on the basis of six specimens collected from off Rausu and Urakawa, Hokkaido Island, Japan. This species is distinguished from its congeners by the following combination of characters: supraocular and parietal spines absent; nuchal spine obscure; uppermost preopercular spine unbranched; no scales between dorsal scale row and lateral line scale row, and no scales below lateral line scale row; supraocular, parietal, and nuchal cirri present; five dark brown saddles dorsolaterally; anal fin rays 13; pectoral fin rays 15; vertebrae 12 + 24–25 = 36–37. Icelus sekii can be mature at the smallest size among the species of Icelus. As a secondary sexual character, the male holotype has unique ensiform flaps on the distal tips of the first dorsal fin.     

LIGHT MICROSCOPY AND ELECTRON MICROSCOPY OF NEPHROSELMIS SPINOSA SP. NOV. (PRASINOPHYCEAE,CHLOROPHYTA)1

Nephroselmis spinosa Suda sp. nov. is described based on LM and EM observations. Two strains of N. spinosa (S222 and SD959‐3) were isolated from sand samples collected from the northwest coast of western Australia. The cells were remarkably right–left flattened and appeared ellipse or bean‐shaped when viewed from their right or left side. A single, parietal, crescent chloroplast was pale green to yellowish green and contained one conspicuous eyespot in its anterior ventral edge near the base of the short flagellum. A pyrenoid with three starch plates was located at the dorsal of the chloroplast. The cells divided by transverse binary cell division, as is common in other species of this genus. This alga possessed four types of body scales, and three scale types were similar to N. olivacea Stein and N. astigmatica Inouye & Pienaar. However, the fourth and outermost scale type was distinctive because although it was a spiny stellate scale with nine spines, one of them extended about 1 μm and was slightly curved with a hook at the end. This scale morphology, an important taxonomic characteristic, has never been described for the genus Nephroselmis. The cell's morphology, pyrenoid structure, hair scales, and cell size were distinctive from previously described Nephroselmis species, and its unique scale characteristic led me to name this newly proposed species “spinosa,” meaning spiny.     

Formation and structure of scales in the Australian lungfish,neoceratodus forsteri (Osteichthyes: Dipnoi)

The large elasmoid scales of the Australian lungfish, Neoceratodusforsteri, are formed within the dermis by unpigmented scleroblasts, growing within a collagenous dermal pocket below a thick glandular epidermis. The first row of scales, on the trunk of the juvenile lungfish, appears below the lateral line of the trunk, single in this species, at around stage 53. The scales, initially circular in outline, develop anteriorly and posteriorly from the point of initiation in the mid‐trunk region, and rows are added alternately below the line, and above the line, until they reach the dorsal or ventral midline, or the margins of the fins. Scales develop later on the ventral surface of the head, from a separate centre of initiation. Scales consist of three layers, all produced by scleroblasts of dermal origin. The outermost layer of interlocking plates, or squamulae, consists of a mineralised matrix of fine collagen fibrils, covered by unmineralised collagen and a single layer of cells. Squamulae of the anterior and lateral surfaces are ornamented with short spines, and the mineralised tissue of the posterior surface is linked to the pouch by collagen fibrils. The innermost layer, known as elasmodin, consists of bundles of thick collagen fibrils and cells arranged in layers. An intermediate layer, made up of collagen fibrils, links the outer and inner layers. The elasmoid scales of N. forsteri can be compared with scale types among other osteichthyan groups, although the cellsand canaliculi in the mineralised squamulae bear littleresemblance to typical bone. J.Morphol., 2012. © 2011 Wiley Periodicals, Inc.