Keeled Scales Research Articles

One new species and records of Ichthydium Ehrenberg, 1830 (Gastrotricha: Chaetonotida) from Sweden with a key to the genus

The freshwater gastrotrich fauna of Sweden is poorly known. Only seven species of freshwater gastrotrichs have been reported so far. This paper is the first in a series of contributions about the Swedish freshwater gastrotrich fauna. Here we describe one new species, Ichthydium skandicum n. sp., from Jämtland, northern Sweden. The new species falls within the boundary of the subgenus Forficulichthys and is morphologically closest to Ichthydium tanytrichum from which it can be differentiated based on the presence of four pairs of dorsal, keeled scales in the posterior trunk region. Moreover, we provide morphometric data for three additional Ichthydium species: I. diacanthum, I. squamigerum and I. tanytrichum, Italian species all of which are reported for the first time outside Italy. Considering the accompanying fauna, a total of thirteen freshwater Gastrotricha are reported for the first time from Sweden. Finally we present a dichotomous key for Ichthydium along with distributional data of the species considered.

A new species of Aspidiophorus (Gastrotricha, Chaetonotida) from the Russian Far East with a key to marine species of the genus

The Russian gastrotrich fauna is virtually unknown, particularly the marine fauna. In the ocean, investigations have been restricted to the White Sea, from where only three fully described species have been reported so far. In this study we describe a new species of Aspidiophorus found in a sandy sample collected from off of Vladivostok (Peter the Great Bay, Sea of Japan). Aspidiophorus oculatus n. sp. is the first marine chaetonotid gastrotrich described from Russia and the first representative of the order Chaetonotida reported from the Sea of Japan. Specimens of the new species are characterized by a body up to 147.5 µm in total length; enveloped by 57 alternating columns of 65–70 keeled, elongate scales. Pharyngeo-intestinal junction at U27; the head bears cephalion, hypostomion, pleuria and a pair of eye-spots; the furca is 20 µm long including the 12-µm long adhesive tube; the ventral interciliary field is naked, with the exception of a pair of elliptical, keeled scales occurring near the anus. Morphological differences between the new species and the other 13 marine con-generic taxa are discussed. A key to the known marine species of the world based on easily identifiable traits, visible in both living and formalin-fixed specimens is provided.

A new microteiid lizard of the genus Acratosaura (Squamata: Gymnophthalmidae) from Serra do Sincorá, State of Bahia, Brazil

A new species of the genus Acratosaura is described on the basis of two specimens obtained at the “campos rupestres” (rocky meadows) near Mucugê municipality, state of Bahia, Brazil. Acratosaura spinosa sp. nov., has ear openings and eyelids, pentadactyl limbs lacking a claw on first toe, a single frontonasal, prefrontals, frontoparietals, parietals, interparietals, occipitals, no collar fold, three pairs of genials, three supraoculars and three superciliaries and is further characterized by presenting 28–31 rows of strongly keeled, lanceolate and imbricate dorsal scales, sides of the neck with keeled scales, striate temporal scales, four longitudinal and 17–18 transverse rows of smooth ventral scales, 28–30 scales around the body, 14 and 19–20 infradigital lamellae under finger IV and toe IV, respectively, 13 total preanal and femoral pores in male, absent in female. The new species differs strikingly in color pattern from its only congener A. mentalis. The two species occur sympatricaly in the high altitude open habitats near the type locality.

A new microteiid lizard of the genus Acratosaura (Squamata: Gymnophthalmidae) from Serra do Sincorá, State of Bahia, Brazil

A new species of the genus Acratosaura is described on the basis of two specimens obtained at the “campos rupestres” (rocky meadows) near Mucuge municipality, state of Bahia, Brazil. Acratosaura spinosa sp. nov., has ear openings and eyelids, pentadactyl limbs lacking a claw on first toe, a single frontonasal, prefrontals, frontoparietals, parietals, interparietals, occipitals, no collar fold, three pairs of genials, three supraoculars and three superciliaries and is further characterized by presenting 28–31 rows of strongly keeled, lanceolate and imbricate dorsal scales, sides of the neck with keeled scales, striate temporal scales, four longitudinal and 17–18 transverse rows of smooth ventral scales, 28–30 scales around the body, 14 and 19–20 infradigital lamellae under finger IV and toe IV, respectively, 13 total preanal and femoral pores in male, absent in female. The new species differs strikingly in color pattern from its only congener A. mentalis. The two species occur sympatricaly in the high altitude open habitats near the type locality.

New Species of Calotes (Reptilia: Squamata: Agamidae) from the Southern Western Ghats, India

A new species is described from the southern Western Ghats of India. The new species was wrongly identified as Calotes andamanensis and is distinguished from it in lacking the antehumeral pit and possessing acutely keeled scales. It is distinguished from all species of the Calotes versicolor group of Smith in having posteroventral orientation of dorsal body scales and is distinguished from all species of the Calotes liocephalus group of Smith in lacking the antehumeral pit. A redescription of C. andamanensis is provided based on the holotype. Calotes andamanensis is a valid species with type locality in the Andaman and Nicobar Islands, India.

Molecular phylogenetics of theAnolis onca series: a case history in retrograde evolution revisited

Anoles of the Anolis onca series represent a dramatic case of retrograde evolution, exhibiting great reduction (A. annectens) and loss (A. onca) of the subdigital pads considered a key innovation for the evolutionary radiation of anoles in arboreal environments. We present a molecular phylogenetic analysis of these anoles and their closest known relatives (A. auratus, A. lineatus, A. meridionalis, and A. nitens) using new mitochondrial DNA sequence data from the ND2 gene, five tRNA genes (tRNA(Trp), tRNA(Ala), tRNA(Asn), tRNA(Cys), tRNA(Tyr)), the origin of light-strand replication, and a portion of the CO1 gene (1,446 aligned base positions, 612 parsimony informative). Our results confirm monophyly of the A. onca series and suggest an evolutionary separation of approximately 10 million years between A. annectens and A. onca. Evolution of subdigital structure in this series illustrates ectopic expression of developmental programs that replace flexible subdigital lamellae of the toepad with rigid, keeled scales resembling dorsal digital scales. Our phylogenetic results indicate that narrowing of the toepad in A. auratus evolved separately from toepad reduction in the A. onca series. Expansion of the subdigital lamellae along the phalanges in A. auratus appears to compensate constriction of lamellae by digital narrowing, maintaining greater climbing capability in this species. Toepad evolution in the lineage ancestral to A. auratus features changes of the same developmental modules as the A. onca series but in the opposite direction. Large molecular distances between geographic populations of A. auratus indicate that its derived toepad structure is at least 9 million years old.

A New Acanthosaura Allied to A. capra Günther, 1861 (Agamidae, Sauria) from Central Vietnam and Southern Laos

A new agamid species from central Vietnam and Southern Laos is described. It is distinguished from A. armata, A. coronata, A. crucigera, and A. lepidogaster by lacking a spine on the occiput between the tympanum and nuchal crest. The new species differs from coronata and lepidogaster by having a large crest and from armata, crucigera, and lepidogaster by lacking a dark marking on the nape. It most closely resembles A. capra, but differs from it by having large keeled scales intermixed with small scales on the lateral and dorsal surface of body (scales relatively uniform in capra). Strong difference in coloration in live of adult males and females of compared species of genus Acanthosaura are described.

ECOLOGY, LIFE-HISTORY, AND BEHAVIOR IN THE AUSTRALIAN SCINCID GENUS EGERNIA, WITH COMMENTS ON THE EVOLUTION OF COMPLEX SOCIALITY IN LIZARDS

Squamate reptiles generally have been ignored in the search for a unified theory for the evolution of sociality due to the perception that they exhibit little social behavior beyond territoriality and dominance hierarchies and display polygynous mating systems. However a growing body of research has revealed unsuspected levels of social complexity and diversity in mating systems within the squamate lineage, particularly among the members of the Australian Scincid genus Egernia. Several species of Egernia are amongst the most highly social of all squamate reptiles, exhibiting stable social aggregations and high levels of long-term social and genetic monogamy. Social complexity is widespread within the Egernia genus, with reports of social aggregations in 23 of the 30 described species. The purpose of this review was to examine the potential for the Egernia genus as a model system for study of the evolution of sociality and monogamy within squamate reptiles.Current evidence indicates there is substantial variability in social complexity both within and between species, with social organization covering the spectrum from solitary to highly social. Four highly social Egernia species are known to live in stable social aggregations consisting of closely related individuals (adults, subadults, juveniles; i.e., ‘family’ groups) that appear to utilize chemical cues to recognize group members (kin recognition). Enhanced vigilance against predators is one presumed benefit of group membership. Additionally, juveniles within social groupings appear to receive low levels of indirect parental care. Several Egernia species create scat piles that mark group territories. Three Egernia species exhibit long-term social and genetic monogamy and several inbreeding avoidance strategies have been documented. However, it is currently unknown whether monogamy is widespread within Egernia.Egernia species occupy a broad range of habitats, although most are terrestrial, saxicolous or semi-arboreal. Several species display an attachment to a permanent home site, generally a rock crevice, burrow or tree hollow. Egernia species take 2–5 years to mature, live for 5–25 years, and are viviparous with litter size positively correlated with body size. Several Egernia species are herbivorous, with the degree of herbivory increasing with body size and during ontogeny in larger species. Most smaller species are either insectivorous or omnivorous. Species of Egernia have a wide range of reptilian, avian, and mammalian predators. Several larger species possess several behavioral and morphological features to prevent their extraction from rock crevices, including highly modified keeled scales and numerous defensive behaviors. Color pattern polymorphism is present in five Egernia species.Potential ecological correlates of sociality and monogamy are discussed. The life-history hypothesis predicts long-lived, late-maturing species should evolve complex sociality. The habitat availability hypothesis relies on the assumption that refugia may be limited in some ecological settings, and group formation is a consequence of co-habitation of available refugia. These hypotheses are not mutually exclusive, and testable predictions are formulated and discussed. Specific future research directions are outlined to take advantage of Egernia as a model system for comparative research on a lineage that represents an independent origin of social organization comparable to that found in birds and mammals.

Phrynosoma intraepidermal receptor: A dorsal intraepidermal mechanoreceptor in horned lizards (Phrynosoma; Phrynosomatidae; Reptilia).

Horned lizards of seven species have intraepidermal sensory receptors on many dorsal body scales, some limb scales, and on head scales (supra- and infralabial, eyelid edges, frontal facing surfaces, and mental chin). These dome-shape scale receptors usually occur singly on keeled scales. Frequently, several receptor-bearing scales are grouped around an enlarged, receptor-bearing spine scale, thus forming multiple-scale complexes. Each dome-shape scale organ is delimited by a circular groove (figured in stereoscopic SEM). Ultrastructural examination of these receptors in Phrynosoma modestum shows them to have characteristics of reptilian intraepidermal mechanoreceptors. Each dome-shape scale organ is covered by thinned α- and β-layers of epidermal keratin. The β-layer forms a thickened ring immediately outside the circular groove and is very thin within the groove. The epidermal portion of the domed receptor contains columnar cells with numerous desmosomal connections. Myelinated nerve fibers and melanophore processes traverse these columnar cells, extending upward from a dermal papilla to just below the α-layer of the dome-shape receptor. Distally, the nerve fibers enlarge to form discoidal nerve terminals, which are surrounded by desmosomes, forming a tonofibrillar basket. Dome-shape scale receptors may function to: (1) detect contact with objects during forward locomotion, (2) locate attacking ants on the lizard's skin and/or, during subterranean burrowing, (3) determine depth below the surface, or (4) sense vibrations through the soil from surface predators or surface rainfall. © 1996 Wiley-Liss. Inc.

Scale Sensillae of the File Snake (Serpentes: Acrochordidae) and Some Other Aquatic and Burrowing Snakes

The acrochordid snakes are aquatic, living in environments with often a poor visibility. It therefore was investigated how these animals detect their prey. Two earlier studies of their scales revealed a rather complex scale organ, composed of hairlike protrusions and plate-like structures. However, no satisfactory explanation was given for the structures found, e.g., an undefined sensilla or a gland. Skin samples from various sites of the body of Acrochordus granulatus and A. javanicus were studied. Scanning electron microscopic pictures revealed that each scale of the head contains up to seven sensillae, and each of the keeled scales of the rest of the body has one. Also a modified Allochrome staining procedure on tissue samples was performed to detect glycogen, which is known to occur in discoidal nerve endings of tactile sense organs of reptiles. Light microscopic slides revealed glycogen particles in a small pillow-shaped area just below the hairlike protrusions of an organ. Moreover, small nerves were recognized near the same location. No indications were found for the scale organs to have a glandular function. Because of the reported reactions of a snake when it is touched by a fish, these scale sensilla are proposed to be very sensitive mechanoreceptors. Comparisons were made with the scale organs of snakes from various habitats, viz. the seasnake Lapemis hardwicki, and burrowing snakes such as Xenopeltis unicolor and Cylindrophis rufus. Their skin sensillae revealed to be of a much simpler outer morphology and only concentrated on specific parts of the head and neck region.

On the Status of Katophis plumbea Macleay (Serpentes: Colubridae)

Sir William Macleay (1877) described Katophis plumbea gen. et sp. nov. from several from Katow, Papua New Guinea. The species has since been placed in the synonymy of the natricine snakes Tropidonotus picturatus and Amphiesma mairii by Boulenger (1893) and Cogger (1979), respectively. Recently, Malnate and Underwood (1988) revised the New Guinean natricine fauna, recognizing 11 species and 1 subspecies in a single genus, Tropidonophis. However, K. plumbea is not mentioned in their work. Although Macleay's description is brief, the keeled scales, low number of midbody scale rows, and presence of a loreal indicate that K. plumbea is a natricine, and the combination of 15 midbody scale rows, single preocular, and type locality suggest that it is a senior synonym of Tropidonophis mairii brongersmai Malnate and Underwood, 1988. Katow is now known as Mawatta, and is on the Binaturi River in the Western District of Papua New Guinea (Parker, 1982), within the known distribution of only T. m. brongersmai. Goldman et al. (1969) identified four Macleay Museum specimens (MMUS 618-621) as syntypes of K. plumbea. These have since been transferred to the Australian Museum, where they are registered as R3189831901 (Cogger, 1979). I have examined all four specimens, and all agree well with the type description, although none is in perfect agreement with the scale counts and measurements provided by Macleay. The range of variation in scalation and measurements of these specimens is as follows: ventrals 139-143; subcaudals 71 (N = 3), reduction to 6 caudal scale rows at level of subcaudal 11-14, reduction to 4 caudal scale rows at level of subcaudal 33-39; supralabials eight (seven on one side of one specimen); preocular single (divided on one side of one specimen); anterior temporals one (50%, N = 8) or two; upper postocular separated from anterior temporals; posterior temporals two; snout-vent length 443-535 mm; and tail length 140-170 mm (N = 3). All characters are in agreement with T. mairii brongersmai. Accordingly, the following synonymy is proposed:

The energetics of shedding: Energy content of snake skin

1. 1. The weight and energy content of sloughed skins of 92 individual snakes of 22 different species in three families were measured. 2. 2. Weight and total energy content of shed skins were highly correlated with body weight. 3. 3. The heat of combustion (kJ/g) of sloughed skins varied significantly among families and was higher in species having unkeeled scales than in those with keeled scales. 4. 4. The presence of keels significantly affected weight of skins, even when skin weight is adjusted for covariance with body weight. 5. 5. Neither body weight nor ambient temperature significantly affected the heat of combustion of sloughed skins. 6. 6. The energy content of shed skin, expressed as a proportion of daily metabolism, decreased with ambient temperature, but the effect is minimized in large snakes. 7. 7. Small snakes expended relatively less energy in sloughed skins than large snakes when the expenditure is expressed in terms of total daily metabolized energy.

Lack of correspondence between genetic and morphologic variability patterns in Atlantic herring (Clupea harengus)

The Atlantic herring (Clupea harengus) stock complex is confusing from the perspectives of both evolutionary biology and systematics. There are numerous ecologically and morphologically divergent stocks classified as species, subspecies, races, tribes, etc. with an unknown degree of genetic differentiation and reproductive isolation between them. The genetic population structure of herring from the Scandinavian waters was analysed electrophoretically. The pattern for distribution of genetic variation was compared to that of the morphological characters most frequently used for stock classification, i.e., the number of vertebrae and keeled scales. Fish were collected from 17 locations distributed from the northern Gulf of Bothnia to the north-east Atlantic off the west coast of Norway. The genetic analysis was based on 17 electrophoretic loci, 13 of which were variable. There are statistically significant allele frequency heterogeneities, but there is a conspicuously small amount of genetic differentiation, even between stocks classified as representing different subspecies. More than 99 per cent of the total gene diversity was found within populations, and genetic distances are typically of the order of 0·001. The genotypic distribution of the total material is very similar to the one expected if all the samples had been drawn from a single panmictic population. There appears to be no association between the variation of morphological characters and that at electrophoretic loci, and this is true for the variation between as well as within samples. Data suggest that stocks either diverged rather recently or that the amount of gene flow between groups of fish classified as stocks has been large enough to prevent substantial differentiation, and that morphologic and ecologic divergence may to a large extent be environmentally induced.

Sexual Dimorphism in Occurrence of Keeled Dorsal Scales in the Eastern Indigo Snake (Drymarchon corais couperi)

Sexual Dimorphism in Occurrence of Keeled Dorsal Scales in the Eastern Indigo Snake (Drymarchon corais couperi)

Identification, morphometrics and cytogenetics of green geckos (Phelsuma) from Praslin, Seychelles (with notes on P. longinsulae, Mahé)

The three species of green geckos (Phelsuma) on the granitic Seychelles can be identified by colour pattern, snout shape and the occurrence of keeled belly scales. There is no difference in chromosome number (2n=S6) between species but multivariate morphometries analysis, based on body proportions and scalation, can distinguish between the species on Praslin Island.

Composition of herring stocks in the Skagerrak-Kattegat and the relations of these stocks with those of the North Sea and adjacent waters

Herring stocks in spawning condition from the waters of the Skagerrak, Kattegat, North Sea, Channel, West Scotland, Orkney-Shetland and Baltic are characterized by the means (and variances) of: number of vertebrae (VS), number of keeled scales (K 2), fish length at the time of formation of the first winter ring ( l 1) and the width of the first winter ring measured along the axis of the otolith (O 1). Five stocks of spawning herring in the Skagerrak-Kattegat are defined. Four of these are spring spawners; the fifth, an autumn spawning stock, is nowadays almost extinct. With the above characteristics of herring in spawning condition as criteria, samples of immature herring from the Skagerrak-Kattegat were separated into indigenous and non-indigenous groups. Almost all herring with two winter rings on their scales (2-group herring) and older herring were spring spawners and of local origin, whereas the 1-group comprised both spring- and autumn-spawned herring. The 1-group herring caught during the International Young Fish Survey (IYFS) in February 1980 and during a trawl survey in September 1980 could be separated into the two spawning groups by their length frequency distribution. These groups displayed characteristics closely corresponding to those of indigenous (Kattegat) spring spawners, and autumn spawners from the North Sea and adjacent waters as identified by previous work. The most important herring stock recently in the fisheries is of Kattegat Spring Spawners, which were not abundant in the catches before the nineteen-seventies. A crude estimation was made of the amount of autumn-spawned herring landed by the Danish and Swedish fishing fleets from the Skagerrak-Kattegat in 1979. Of a total landing of almost 60 000 tonnes, approximately 6% could have been autumn-spawned herring.

Taxonomía de algunos microtéidos (Squamata) de Venezuela, I: Variación y distribución geográfica de <i>Euspondylus acutirostris</i> y descripción de un nuevo <i>Euspondylus</i> del nordeste de Venezuela

Only two species of the microteiid lizard genus Euspondylus (E. acutirostris and E. phelpsorum) had been reported from Venezuela. New records of the poorly known gymnophthalmid lizard Euspondylus acutirostris are reported extending its known range along the Coastal Range and Sierra de Aroa (north-central Venezuela) and Sierra de San Luis (northwestern Venezuela), all records occurring at the cloud forest above 1000 m. Seven body measurements were included and morphological variation is described based on at least 17 new specimens. Sexual dimorphism is determined in, at least, eight characteristics of size and squamation. Specimens were found in epiphytic bromeliads and the ground. The populations from Sierra de Aroa and Sierra de San Luis (only one specimen known from each locality), differ from those of the Coastal Range (supposedly the nominal population) in some morphological and coloration features, suggesting that the former two could represent different taxonomical entities. A new species of Euspondylus is described based on a female (taken within a bromeliad) from Cerro El Humo, Sucre, northeastern Venezuela. It differs from congeners mainly by having keeled scales on the limbs and a very acute snout.

Two New Genera of African Bufonids, with Remarks on the Phylogeny of Related Genera

keeled; a nuchal crest of three spinose scales separated by two to six small, keeled scales; vertebral scale row posteriorly with widely separated enlarged scales. Male unknown, but female (and, therefore, probably male) with keeled scales on side of tail; two rows of enlarged, keeled subcaudals. Material.-Holotype, adult female with one large egg; snout-vent 60.3 mm.; supralabials 11, infralabials 12. Locality.-Sarawak: Fifth Division, Mount Murud.

Vertebral Variation in Teleostean Fishes. III. Isospondyli

This paper does not give a detailed description of the backbone of any one of the eight isospondylid species examined. Instead, selected data have been used in a discussion of the broad principles of vertebral variation, as seen in fishes of the order Isospondyli. This was considered to be of greater value than a catalogue of vertebral details for each of a small number of already wellknown species. Even so, sufficient has been said to enable any worker to identify the backbone of any one of the eight species, as well as to obtain a most discriminative description of the backbone of any other species of Isospondyli he may examine. A distinction is drawn between the countable vertebral characters, which are statistics for the precise measurement of vertebral variation, and the 'marker' characters, which provide the means for recognition 'on sight'. It is believed that vertebral characters of both kinds might be profitably employed in the study of different biological populations of the same species. The correlation between vertebral characters and other bodily features, such as keeled scales, position of fins and anus, and contour of body cavity, receives attention, and is related to metamerism. Finally, the occurrence of autogenus vertebral arches and the bifid condition of the neural spines in the isospondylid backbone is shown to be primitive and not restricted to the order.

Herring Investigations at Plymouth. II. The Average Number of Vertebrae for Herrings from the English Channel and South-East of Ireland

The published observations of other workers, on samples of herrings taken from the area under consideration, whether they relate to the study of such morphological characters as the number of vertebræ and keeled scales, or are chiefly concerned with the examination of the growth of the fishes as indicated by their scales, demonstrate very clearly that the eastern, central and western sectors of the area are visited by herrings which differ in character. It will be convenient to summarise the opinions of these workers under the headings of the statistical regions in which the samples were taken. The reader is referred to the chart on page 269, which shows the geographical extent of the regions dealt with.