Integumentary Structures Research Articles

The evolution of the feather: Sinosauropteryx, life, death and preservation of an alleged feathered dinosaur

Among the spectacular dinosaur fossils reported from the Jehol Group of northeastern China is the most celebrated, Sinosauropteryx, which continues to excite interest in questions concerning feather origins—most recently with alleged identifications of melanosomes and colour in its integumental structures, which proved unfounded. The crucial significance of Sinosauropteryx is undoubtedly the focus on its basal theropod status and potentially pivotal position in informing models of the early evolutionary origin of modern feathers. On the basis of new evidence in Sinosauropteryx NIGP 127587 and GMV 2124, it is shown here that the alleged protofeathers were not free filaments but part of a composite tissue. It is shown that the tail terminates in a unique, smoothly edged, spatula-shaped structure. The dinosaurs died in the vicinity of a lake. For the first time, the taphonomy of Sinosauropteryx is investigated on the basis of aboveground decomposition experiments on living animals so as to get a better understanding of conditions preceding the death of the animal, its death, decomposition and finally preservation of soft tissue as manifested in the fossil. The signs point strongly to invertebrate colonization of the carcass of Sinosauropteryx rather than vertebrate predation or scavenging, with moderate decay associated with the purge fluids while major decay was forestalled by burial, at most a few days after death. Lastly, a theory that the opisthotonic posture of fossils such as Sinosauropteryx NIGP 127587 occurred perimortem as a consequence of neural spasms provides the basis for a forensic reconstruction of the stages leading to the dinosaur’s death and the final preserved position of the external, dorsally preserved soft tissue, which proves to be more consistent with a uniform crest than individual, free protofeathers.

Measuring stress in wildlife: techniques for quantifying glucocorticoids

Stress responses play a key role in allowing animals to cope with change and challenge in the face of both environmental certainty and uncertainty. Measurement of glucocorticoid levels, key elements in the neuroendocrine stress axis, can give insight into an animal's well-being and can aid understanding ecological and evolutionary processes as well as conservation and management issues. We give an overview of the four main biological samples that have been utilized [blood, saliva, excreta (feces and urine), and integumentary structures (hair and feathers)], their advantages and disadvantages for use with wildlife, and some of the background and pitfalls that users must consider in interpreting their results. The matrix of choice will depend on the nature of the study and of the species, on whether one is examining the impact of acute versus chronic stressors, and on the degree of invasiveness that is possible or desirable. In some cases, more than one matrix can be measured to achieve the same ends. All require a significant degree of expertise, sometimes in obtaining the sample and always in extracting and analyzing the glucocorticoid or its metabolites. Glucocorticoid measurement is proving to be a powerful integrator of environmental stressors and of an animal's condition.

SEM study of Sandersiella chilenica sp.nov. (Cephalocarida), with a review of the Integumentary Structures and Functional Adaptations in the Group

Se describe Sandersiella chilenica sp.nov., Cefalocarido encontrado en la pequena Bahia de Coliumo, Chile central (36o 32' lat S.; 72o56' long W), en un solo punto de una grilla de 11 estaciones estudiadas mensualmente durante 198283, en fondos con predominancia de arena fina, limo y arcilla. Solo otras cuatro especies del genero son conocidas (Sandersiella acuminata Shiino, 1965 y S.kikuchii Shimomura & Akiyama, 2008, de Japon, S. calmani Sanders & Hessler, 1973 encontrada frente a la costa de Peru, y S.bathyalis Hessler & Sanders, 1973 de Walvis Ridge, Atlantico S.E. y frente a Santos, Brasil). S. chilenica sp.nov. es diferenciable por una longitud maxima relativamente mayor, las ramas caudales mas cortas y proporcionalmente mas gruesas, y por la forma orbicular del segundo podomero del exopodito del toracopodo 6. El estudio de la morfologia externa con microscopia de barrido nos ha permitido proponer la diferenciacion y clasificacion de setas y otras estructuras cuticulares externas, siguiendo las clasificaciones propuestas para Crustaceos en general, reconociendo que falta clarificar si se trata de simples analogias o de verdaderas homologias

The evolution of the feather: Sinosauropteryx, a colourful tail

A recent development in the identification of feathers in fossils by means of melanosomes was used to suggest that structures observed in an SEM of a filament in the basal theropod dinosaur, Sinosauropteryx, were phaeomelanosomes and that they represented conclusive evidence that the filaments were early feathers. At the most basic level, the claims of phaeomelanosomes are shown here to be founded on an optical illusion created when the SEM is reproduced at low image size—viewed at larger image size (~2× original) the structures are nondescript in both size and shape and impossible to equate with phaeomelanosomes. At a higher level of investigation, the study is seriously questioned for ignoring standard scientific protocol: despite size and shape being critical to the identification of the phaeomelanosomes, no statistically viable measurements of the structures (particles) were made—the measurements, which are simply conjectured, are shown here to be incorrect in the speculated sizes, and in shapes; inferences made on vital characters from birds and advanced non-avian dinosaurs, e.g. with respect to colour banding, are without confirmation in the test animal but conjectured on circular argumentation; alternative arguments, e.g. that the particles might be bacteria or colour from the overlying skin, are peremptorily dismissed or not considered; suggestions that the particles are embedded within the filament are without support since there is no evidence of cross-sections or tangential sections either made or occurring serendipitously—only a single section is reported, apparently of the filament’s surface. False dichotomies such as, if the structures are not bacteria they must be melanosomes, are questioned given that one of the most important factors in the taphonomy of ancient (structures in question, ~130 MYR) fossilised filaments i.e., decomposition—that the structures might reasonably represent the degraded remains of the filaments—is not even considered. Here, from experiments on the decomposition of native collagen in fish and reptilian dermis, SEMs of their ultrastructure show that distinctive spherical, elliptical or oblate particles, even more so than those figured in Sinosauropteryx, typically form during degradation. This is confirmed in SEMs of degraded collagen fibres in a 225-MYR ichthyosaur fossil, virtually point by point. In addition numerous small bead-like structures in the filament of Sinosauropteryx bear a striking resemblance to the unique 67-nm D-bands of collagen, in both shape and size. This paper does not question the value of scientifically meritorious identifications of melanosomes, as indeed of collagen and keratin, in interpreting the integumental structures of fossil animals. However, allegations of phaeomelanosomes in Sinosauropteryx are shown to be without scientific merit.

Possible link connecting reptilian scales with avian feathers from the early Late Jurassic of Kazakstan

Organic tissue of a recently found second specimen of feather-like Praeornis from the Karabastau Formation of the Great Karatau Range in southern Kazakstan, has a stable carbon isotope composition indicative of its animal affinity. Three-dimensional preservation of its robust carbonised shaft indicates original high contents of sclerotic organic matter, which makes the originally proposed interpretation of Praeornis as a keratinous integumental structure likely. The new specimen is similar to the holotype of Praeornis in the presence of three ‘vanes’ on a massive shaft not decreasing in width up to near its tip. Unlike it, the vanes are not subdivided into barbs and the pennate structure is expressed only in the distribution of organic-matter-rich rays. Similar continuous blades border the ‘barbs’ in the holotype, but the organic matter was removed from them by weathering. It is proposed that the three-vaned structure is a remnant of the ancestral location of scales along the dorsum and their original function in sexual display, similar to that proposed for the Late Triassic probable megalancosaurid Longisquama. Perhaps subsequent rotation around the shaft, in the course of evolution from an ancestral status similar to Praeornis towards the present aerodynamic and protective function of feathers, resulted in the tubular appearance of their buds.

Functional characterization of bursicon receptor and genome-wide analysis for identification of genes affected by bursicon receptor RNAi

Bursicon is an insect neuropeptide hormone that is secreted from the central nervous system into the hemolymph and initiates cuticle tanning. The receptor for bursicon is encoded by the rickets (rk) gene and belongs to the G protein-coupled receptor (GPCR) superfamily. The bursicon and its receptor regulate cuticle tanning as well as wing expansion after adult eclosion. However, the molecular action of bursicon signaling remains unclear. We utilized RNA interference (RNAi) and microarray to study the function of the bursicon receptor (Tcrk) in the model insect, Tribolium castaneum. The data included here showed that in addition to cuticle tanning and wing expansion reported previously, Tcrk is also required for development and expansion of integumentary structures and adult eclosion. Using custom microarrays, we identified 24 genes that are differentially expressed between Tcrk RNAi and control insects. Knockdown in the expression of one of these genes, TC004091, resulted in the arrest of adult eclosion. Identification of genes that are involved in bursicon receptor mediated biological processes will provide tools for future studies on mechanisms of bursicon action.

Calcified Integumentary Structures in Anurans

Although often overlooked, the integument of many vertebrates is reinforced by skeletal elements. In anurans these calcified structures include osteoderms, bone‐rich elements, and the lamina calcarea, a calcified, acellular layer that lacks collagen. We investigated the histology of anuran integument with a special focus on taxa developing skeletal elements. When present, the lamina calcarea forms a thin but discrete horizon at the interface between the superficial and deep dermis. This layer is rich in glycosaminoglycans (GAG) and is structurally unlike bone and cartilage. In contrast, anuran osteoderms are composed of cellular bone with limited GAG. A partial ontogenetic series of the tree frog Phyllomedusa bicolor provides the first details of anuran osteoderms development. In P. bicolor osteoderm development begins as a cluster of small calcified centres localized over the head. With continued body growth, osteoderms become larger in size and become distributed across the dorsal and ventral surfaces of the body, and across the limbs. The leaf litter frog Brachytarsophyrys cariensis is unusual in developing both osteoderms (on the dorsal body surface) and a lamina calcarea (on the ventral body surface). Our data shows that anuran integument has the ability to form skeletal elements and suggests that these elements arose in multiple anuran lineages.Grant Funding Source: NSERC

The integument of Psittacosaurus from Liaoning Province, China: taphonomy, epidermal patterns and color of a ceratopsian dinosaur

Preserved skin of small dinosaurs is rare. Here, a specimen of the ceratopsian dinosaur, Psittacosaurus, presents some of the best preserved epidermal scales observed to date in a relatively small dinosaur, over wide areas extending from the head to the tail. We study the preserved epidermis of SMF R 4970, the different types of scales, color, and patterns, and their respective locations in the body. We use modern application of high-power digital imaging for close-up analysis of the tubercles and fragments of preserved color. Three types of scales are preserved, large plate-like scales, smaller polygonal scales or tubercles, and round pebble-like scales. The sizes of the plate-like scales vary in different parts of the body and vanish altogether posteriorly. Light and dark cryptic patterns are created by the associations of the tubercle and plate-like scales, and there is also evidence of countershading in the proximal caudal region, the body darker dorsally and lighter ventrally. Perhaps most impressive are the distinctive pigmented impressions of scales over most of the skeletal elements. The pigmentation follows the curvature of the bones implying that when it was deposited, the skin was still pliable and able to wrap around the visible parts of the elements. The present record of color is the first in a non-theropod dinosaur and only the second record in a non-avian dinosaur. Because of its resistance to degradation and ability to produce various color tones from yellows to blacks, we suggest that melanin was the dominant chemical involved in the coloration of Psittacosaurus. The data here enable us to reconstruct the colors of Psittacosaurus as predominantly black and amber/brown, in cryptic patterns, somewhat dull, but useful to a prey animal. Indeed, skin pigment within a partially degraded bone indicates that Psittacosaurus was scavenged shortly after death. The theropod dinosaur Sinosauropteryx has recently been reported to have naturally pigmented integumental structures, which the authors interpret as proof that they are protofeathers and not support fibers of collagen. Our findings in Psittacosaurus, on the other hand, indicate a more parsimonious and less profound alternative explanation, i.e., decomposition of the skin releases pigments that readily permeate underlying structures.

Response to comments by G. Mayr to my paper “Dinosaur protofeathers: pushing back the origin of feathers into the Middle Triassic?”

Primordial stages in feather evolution including an allegedly new type of protofeather (Xu et al. 2009) as reportedly identified in the Chinese dinosaurs were questioned (Lingham-Soliar in J Ornithol 2009) on identifications based on poor scientific methodology, errors and tautological rationalizations in critical issues. Criticisms were also directed at certain findings by Mayr et al. (2002) on integumental structures in the tail of a psittacosaur dinosaur from the early Cretaceous of China. Important allegations concerning a possible keratinous chemistry of the integumental structures and presence of a hollow lumen at their centre were considered poorly supported and consequently unsound. Mayr (2009) responded by questioning some of my remarks. Here, I respond to his comments.

Dinosaur protofeathers: pushing back the origin of feathers into the Middle Triassic?

Reports of primordial feathers (protofeathers) in dinosaurs have received widespread interest. Recently, it was proposed that a novel protofeather in the theropod dinosaur Beipiaosaurus completes the transitional series in the evolution of the feather and provides the first evidence of filamentous feathers as display in nonavian theropods. A more far-reaching evolutionary ramification is the claim that these structures push the origin of monofilamentous integumentary structures into the Middle Triassic or earlier. I discuss problems with the analyses within the broader context of studies concerning the hypothesis of protofeathers, and show that affinity between the integumentary structures in Beipiaosaurus and feathers is improbable. The scientific methodology is questioned by its failure to make phenomena perceivable by objective means, by questionable rationalizations in critical issues, and by lack of consideration of exceptions to the postulated thesis. The notion that primordial feathers occurred in a clade more inclusive than the Coelurosauria and that it is supported by the presence of integumental structures in Psittacosaurus is analyzed and rejected.

Development and functional significance of dorsal air bags in nestlings of Monteiro's Hornbill Tockus monteiri

This study describes the morphology and investigates the possible function of the air bags found on the nestlings of Monteiro's Hornbill Tockus monteiri. These air bags increased in size with age and mass of the nestling until 14 d of age, and then decreased in size. By 20 d of age, the air bags were absent. Histological examination of the air bags showed that they were integumentary structures composed of an outer epidermis and an inner dermis. The air bags were not connected to the respiratory system. The body temperature (Tb) of Monteiro's Hornbill nestlings increased significantly with increasing age. Comparisons of ambient, nest and female body temperatures were made. Female Tb was higher than ambient and nest temperatures. It appears that airbags may provide an effective intermediate insulatory mechanism for the nestlings while they are developing their thermoregulatory ability. Therefore, it is suggested that the dorsal air bags evolved primarily for thermoregulatory benefits to nestlings, although further research is required.

An Early Cretaceous heterodontosaurid dinosaur with filamentous integumentary structures

Ornithischia is one of the two major groups of dinosaurs, with heterodontosauridae as one of its major clades. Heterodontosauridae is characterized by small, gracile bodies and a problematic phylogenetic position. Recent phylogenetic work indicates that it represents the most basal group of all well-known ornithischians. Previous heterodontosaurid records are mainly from the Early Jurassic period (205-190 million years ago) of Africa. Here we report a new heterodontosaurid, Tianyulong confuciusi gen. et sp. nov., from the Early Cretaceous period (144-99 million years ago) of western Liaoning Province, China. Tianyulong extends the geographical distribution of heterodontosaurids to Asia and confirms the clade's previously questionable temporal range extension into the Early Cretaceous period. More surprisingly, Tianyulong bears long, singular and unbranched filamentous integumentary (outer skin) structures. This represents the first confirmed report, to our knowledge, of filamentous integumentary structures in an ornithischian dinosaur.

Cordaitalean Seed Plants from the Early Permian of North China. II. Reconstruction of Cordaixylon tianii

From a single Early Permian locality in the Taiyuan Formation of northern China, a new whole‐plant cordaitalean is reconstructed and named Cordaixylon tianii (B. Tian and S.‐J. Wang) S.‐J. Wang and J. Hilton sp. nov. The reconstruction is based on pairs of plant organs found in organic attachment, supplemented with cases where two or more co‐occurring morphospecies share distinctive anatomical features. Stems have sympodial primary vascular architecture with endarch primary xylem maturation of the cauline bundles, which surround a septate pith. Leaf traces are endarch, most diverging from the pith margin as double bundles (less frequently singly) and bearing leaves in 3/8 and 5/13 phyllotaxis. Leaves are long and straplike, resembling those of the previously reconstructed Cordaixylon dumusum Rothwell and S. Warner, but with a geniculate posture that justifies their segregation as Cordaites tianii S.‐J. Wang and J. Hilton sp. nov. Both male and female cones are compound, borne irregularly as epicormic branches, and when isolated conform to the morphogenus Cordaitanthus. Pollen cones with numerous pollen organs borne on apically concentrated fertile scales are largely consistent with the morphospecies Cordaitanthus concinnus Delevoryas, but subtle distinctions permit their description as C. tianii S.‐J. Wang and J. Hilton sp. nov. Ovulate cones are described as Cordaitanthus shanxiensis S.‐J. Wang and J. Hilton sp. nov.; each cone contains several cardiocarpalean ovules that have a distinctive tuberculate integumentary structure and are assignable to the morphospecies Cardiocarpus tuberculatus S.‐J. Wang, J. Hilton, and B. Tian. The reconstructed plant most closely resembles C. dumusum from the Late Pennsylvanian of North America, but (often subtle) diagnostic characters are well distributed across the organs of the two conceptual whole plants, permitting confident distinction at species level. The plant is reconstructed as a large, suberect or fully erect shrub.

COEVOLUTION BETWEEN ATTINE ANTS AND ACTINOMYCETE BACTERIA: A REEVALUATION

We reassess the coevolution between actinomycete bacteria and fungus-gardening (attine) ants. Actinomycete bacteria are of special interest because they are metabolic mutualists of diverse organisms (e.g., in nitrogen-fixation or antibiotic production) and because Pseudonocardia actinomycetes are thought to serve disease-suppressing functions in attine gardens. Phylogenetic information from culture-dependent and culture-independent microbial surveys reveals (1) close affinities between free-living and ant-associated Pseudonocardia, and (2) essentially no topological correspondence between ant and Pseudonocardia phylogenies, indicating frequent bacterial acquisition from environmental sources. Identity of ant-associated Pseudonocardia and isolates from soil and plants implicates these environments as sources from which attine ants acquire Pseudonocardia. Close relatives of Atta leafcutter ants have abundant Pseudonocardia, but Pseudonocardia in Atta is rare and appears at the level of environmental contamination. In contrast, actinomycete bacteria in the genera Mycobacterium and Microbacterium can be readily isolated from gardens and starter-cultures of Atta. The accumulated phylogenetic evidence is inconsistent with prevailing views of specific coevolution between Pseudonocardia, attine ants, and garden diseases. Because of frequent acquisition, current models of Pseudonocardia-disease coevolution now need to be revised. The effectiveness of Pseudonocardia antibiotics may not derive from advantages in the coevolutionary arms race with specialized garden diseases, as currently believed, but from frequent recruitment of effective microbes from environmental sources. Indeed, the exposed integumental structures that support actinomycete growth on attine ants argue for a morphological design facilitating bacterial recruitment. We review the accumulated evidence that attine ants have undergone modifications in association with actinomycete bacteria, but we find insufficient support for the reverse, modifications of the bacteria resulting from the interaction with attine ants. The defining feature of coevolution--reciprocal modification--therefore remains to be established for the attine ant-actinomycete mutualism.

The ontogeny of the shell in side‐necked turtles, with emphasis on the homologies of costal and neural bones

Although we are starting to understand the molecular basis of shell development based on the study of cryptodires, basic comparative ontogenetic data for the other major clade of living turtle, the pleurodires, are largely missing. Herein, the developmental and phylogenetic relation between the bony shell and endoskeleton of Pleurodira are examined by studying histological serial sections of nine specimens of three different species, including an ontogenetic series of Emydura subglobosa. Emphasis is given to the portion of the carapace in which ribs and vertebral spinous processes become part of the carapace. Central questions are how neurals and costals are formed in pleurodiran turtles, whether costals and neurals are of endoskeletal or exoskeletal origin, and what ontogenetic factors relate to neural reduction of some Pleurodira. The neurals and costals do not develop as independent ossification centers, but they are initial outgrowths of the periosteal collar of endoskeletal ribs and neural arches. Slightly later in development, the ossification of both shell elements continues without a distinct periosteum but by metaplastically ossifying precondensed soft-tissue integumentary structures. Through ontogeny, ribs of the turtles studied are closely associated with the hypaxial intercostalis musculature while epaxial interspinalis musculature connects the neural arches. We here propose an alternative structural hypothesis for the neural reduction and, ultimately, the complete loss of the neural series. The complete reduction of neurals in Emydura spp. may be linked to heterochrony, accompanied by a restricted influence of epaxial musculature and epidermal-dermal interaction in shell bone formation.

Role of sugars in surface microbe–host interactions and immune reaction modulation

Sugars in the form of monosaccharides, oligosaccharides, polysaccharides and glycoconjugates (glycoproteins, glycolipids) are vital components of infecting microbes and host cells, and are involved in cell signalling associated with modulation of inflammation in all integumental structures. Indeed, sugars are the molecules most commonly involved in cell recognition and communication. In skin, they are essential to epidermal development and homeostasis. They play important roles in microbial adherence, colonization and biofilm formation, and in virulence. Two groups of pathogen recognition receptors, C-type lectins (CTL) and their receptors (CTLR), and the Toll-like receptors enable the host to recognize pathogen-associated molecular patterns (PAMPs), which are mainly glycolipids. The CTLs can recognize a wide variety of bacteria, fungi and parasites and are important in phagocytosis and endocytosis. TLRs are expressed on the surfaces of a variety of cells, including keratinocytes, dendritic cells, monocytes and macrophages; they play a major role in innate immunity. Interaction of TLRs with PAMPs initiates a cascade of events leading to production of reactive oxygen intermediates, cytokines and chemokines, and promotes inflammation. Exogenous sugars can block carbohydrate receptors and competitively displace bacteria from attachment to cells, including keratinocytes. Thus sugars may provide valuable adjunctive anti-inflammatory and/or antimicrobial treatment. A promising approach is the use of a panel of carbohydrate derivatives with anti-adhesive efficacy against bacteria frequently involved in diseases affecting skin and other epithelia. More complete characterization of sugar receptors and their ligands will provide further keys to use of carbohydrates in immunomodulation and infection control in skin.

A new Chinese specimen indicates that ‘protofeathers’ in the Early Cretaceous theropod dinosaur Sinosauropteryx are degraded collagen fibres

Alleged primitive feathers or protofeathers in the theropod dinosaur Sinosauropteryx have potentially profound implications concerning feather morphogenesis, evolution offlight, dinosaur physiology and perhaps even the origin of birds, yet their existence has never been adequately documented. We report on a new specimen of Sinosauropteryx which shows that the integumental structures proposed as protofeathers are the remains of structural fibres that provide toughness. The preservation in the proximal tail area reveals an architecture of closely associated bands offibres parallel to the tail's long axis, which originate from the skin. In adjacent more exposed areas, the fibres are short, fragmented and disorganized. Fibres preserved dorsal to the neck and back and in the distal part of the tail are the remains of a stiffening system of a frill, peripheral to the body and extending from the head to the tip of the tail. These findings are confirmed in the holotype Sinosauropteryx and NIGP 127587. The fibres show a striking similarity to the structure and levels of organization of dermal collagen. The proposal that these fibres are protofeathers is dismissed.

Topographical and numerical study of the idiosomal integumentary structures of the larva of four Neotropical species of Amblyomma Koch, 1844 (Acari: Ixodidae)

Integumentary structures of the larvae of Amblyomma longirostre (Koch, 1844), A. parvum Aragão, 1908, A. rotundatum Koch, 1844 and from three populations of A. cajennense (Fabricius, 1787) were studied using light microscopy. A new nomenclature for the localisation of the integumentary structures is proposed. Three types of integumentary structures were identified in the larval idiosoma of the four Amblyomma species: lyrifissures, small glands and large wax glands. These structures were observed isolated or associated over the entire idiosoma, except in the scutum, which lacked lyrifisures and large wax glands. Large wax glands were the most stable within and between the tick species, followed by lyrifissures and small glands. Small glands, although relatively stable, showed the highest number of numerical variations within and between the tick species. Even though there were intra-population variations in the topographical and numerical pattern of some integumentary structures of A. cajennense larvae, there was a definitive pattern for most of the specimens, as showed by the similar modal and mean numbers of integumentary structures per tick side. The patterns of lyrifissures, small glands and large wax glands showed little differences when compared between the four Amblyomma species; however, a few differences were well evident. These differences were sufficient to differentiate larvae of the four species. Thus, we expect that the study of integumentary structures on the larvae of other Amblyomma species will be useful in future taxonomic keys for the identification of Amblyomma larvae from the Neotropical region.

NESTING BIOLOGY, MORPHOLOGICAL REMARKS, AND DESCRIPTION OF THE MATURE LARVA OF MELLINUS ARVENSIS OBSCURUS (HYMENOPTERA: CRABRONIDAE) IN NEPAL

Recently re-named as a sub-species of Mellinus arvensis, Mellinus arvensis obscurus Handlirsch 1888 was investigated ecologically and morphologically in Nepal, in order to underline the most important differences with the well known M. arvensis arvensis. Mellinus arvensis obscurus females nested in clumped aggregations on inclined plains at high altitudes, both on sunny bare soil and on a shaded grassy one. Beginning of monsoon season probably interfered with wasp activity, and females performed few provisioning flights during the day. Prey consisted of a broad range of Diptera, except for one case of a spider. Many females were observed not provisioning a nest but floating on the nesting site, and many intraspecific interactions suggested a high degree of usurpation attempts. At least one species of flies and two of ants probably acted as natural enemies of the wasp. Morphological observations on females showed that the Nepal population shares more similarities (shape of tergite I, body punctation) with the European populations than with the closer Japanese population; melanization is strong, according to west-east and altitudinal cline. The mature larva of M. arvensis obscurus Handlirsch is described, illustrated, and compared with the other mature larva of the genus. The differences between both larvae mainly lie in the presence/absence, and number or differentiation of integumental structures. We conclude that morphological traits are more important than ecological and behavioral ones in distinguishing M. arvensis obscurus from M. arvensis arvensis.

DEVELOPMENT OF INTEGUMENTARY STRUCTURES IN ROUSETTUS AMPLEXICAUDATUS (MAMMALIA: CHIROPTERA: PTEROPODIDAE) DURING LATE-EMBRYONIC AND FETAL STAGES

The pattern of development of integumentary structures and associated tissues in the megachiropteran bat Rousettus amplexicaudatus is described on the basis of 18 specimens ranging in crown–rump length (CRL) from 8.5 to 44.4 mm. The ontogenetic sample encompasses specimens that correspond to stages 16 through 22 of the phyllostomid Carollia perspicillata (late-embryonic) as well as fetal stages. Although the earlier stages of R. amplexicaudatus show little deviations in relative timing or anatomy from Carollia, later ones are increasingly different. Integumentary structures show different degrees of developmental penetrance. Derived features in embryonic stages are clearly reflected in adult structures such as a great enlargement of the handplate in relation to the footplate at the moment in which both are fully differentiated. We propose that patagium morphogenesis includes development of dactylopatagium by initial retention and posterior growth of interdigital tissue, coupled with digit elongation; and development of pro-, plagio-, and uropatagium in association with wing muscles unique to bats. Additionally, allometric trends in wingspan, total wing area, arm-wing area, and hand-wing area were estimated with respect to CRL. Changes in the terminology of some Carollia stages (16 and 18) are proposed to facilitate comparisons across bat species.