Fabrication process for combustion chamber/nozzle assembly

An integral, lightweight combustion chamber/nozzle assembly for a rocket engine has a refractory metal shell defining a chamber of generally frusto-conical contour. The shell communicates at its smaller end with a rocket body, and terminates at its larger end in a generally contact contour, which is open at its terminus and which serves as a nozzle for the rocket engine. The entire inner surface of the refractory metal shell has a thermal and oxidation barrier layer applied thereto. An ablative silica phenolic insert is bonded to the exposed surface of the thermal and oxidation barrier layer. The ablative phenolic insert provides a chosen inner contour for the combustion chamber and has a taper toward the open terminus of the nozzle. A process for fabricating the integral, lightweight combustion chamber/nozzle assembly is simple and efficient, and results in economy in respect of both resources and time

Andean snakes

37 p. : ill., map ; 24 cm.Includes bibliographical references (p. 35-37)."Saphenophis, new genus, accommodates five species of South American colubrid snakes: Dromicus boursieri Jan and Sordelli (type species), Liophis atahuallpae Steindachner, Rhadinaea antioquiensis Dunn, Rhadinaea tristriatus Rendahl and Vestergren, and Saphenophis sneiderni, new species (from southwestern Colombia). These are defined and diagnosed, and placed in two species groups. No support is given a recent suggestion that the type species (boursieri) may be closely allied with some West Indian snakes (Antillophis Maglio, 1970). Saphenophis belongs with an undefined group of New World colubrid genera characterized by a usually bilobed, spinose hemipenis that is distally calyculate and noncapitate or semicapitate (but lobes not contained within single capitulum), with a deeply forked sulcus spermaticus. It is suggested that this type of hemipenis is more primitive than the single or slightly bilobated type in which the entire calyculate area is contained within a single capitulum and bifurcation of the sulcus spermaticus is reduced. Saphenophis boursieri occurs on both Pacific and Atlantic drainages; it possibly adapted to a wide range of environments in the course of vertical habitat displacement during Pleistocene glaciation. Other species of Saphenophis are thought to be isolates differentiated from stock(s) fragmented by upward displacement of montane habitats, in a drier postglacial period. Thus, evolution of some or all the species is suggested to have occurred fairly recently in the Quaternary"--P. [1]

Vine snakes

50 p. : ill., 2 maps ; 26 cm.Includes bibliographical references (p. 48-50)."The widespread Neotropical genus Imantodes (Colubridae) is partially revised in order to determine the relationships of a distinctive new snake discovered on an isolated ridge in eastern Panama. The six species of blunt-headed vine snakes now recognized are equally divided between two monophyletic assemblages - the cenchoa and lentiferus groups - based on hemipenial characters, maxillary dentition, relative tongue (fork) length, and coloration (reduction of pigmentation in the primitive blotched markings) ... From examination of type specimens of old names currently in the synonymy of Imantodes cenchoa, it is concluded that (1) the placement of Himantodes anisolepis and H. platycephalus is correct, (2) Himantodes hemigenius is a junior synonym of I. gemmistratus, and (3) the name Himantodes semifasciatus is a composite of I. cenchoa and I. gemmistratus. A lectotype is designated to keep semifasciatus with cenchoa, but the nominal subspecies Imantodes cenchoa semifasciatus is nonetheless considered invalid. A lectotype also is designated for Imantodes lentiferus"--P. 2-3

Green anole

14 p. : ill., map ; 24 cm.Includes bibliographical references (p. 13-14)."Anolis procellaris is described from lowland forest on the Atlantic coast of western Panama. The new species is a small, slender lizard of uncertain relationships. It is superficially similar to Anolis chloris Boulenger, an allopatric species that is found from eastern Panama to northwestern Ecuador, but osteological evidence and different kinds of green pigmentation indicate that the two species belong in different sections of the genus Anolis. A key is provided for determining the species of green anoles that occur in Panama, and photographs from life are presented of the following species: Anolis biporcatus, A. chloris, A. chocorum, A. frenatus, A. latifrons, and A. procellaris. Anolis aquaticus is incidentally recorded from Panama for the first time; the known geographic range of anolis chocorum is extended southward to the Río San Juan in western Colombia, and a specimen from a disjunct population in extreme western Panama is tentatively assigned to this species"--P. [1]

Reappraisal of Rhadinaea antioquiensis, Rhadinaea tristriata, Coronella whymperi, and Liophis atahuallpae

27 p. : ill., map ; 24 cm.Includes bibliographical references (p. 26-27)

Andean poison frog

23 p. : ill. ; 26 cm.Includes bibliographical references (p. 23)."Dendrobates bombetes, new species, is a small, red-striped frog inhabiting the western Andes near Cali, Colombia. Nearest relatives are the Ecuadoran D. abditus and the northern Colombian D. opisthomelas; these three Andean species are considered a monophyletic unit of the 'minutus group' because of a larval synapomorphy. The name D. reticulatus is resurrected from the synonymy of D. quinquevittatus in Amazonian Peru. Dendrobates bombetes was found in two forest types at localities separated by 30 km. distance and 800 m. elevation. Differences in population structure suggest the possibility that either reproductive success or juvenile survivorship may be inversely density dependent. Cool montane forest islands supported dense, presumably stable populations having few juveniles and a high proportion of large (old?) adults. Marginal habitat in relatively xeric gallery forest supported a small population having significantly more juveniles and smaller (younger?) adults, suggesting rapid turnover in a precarious habitat. One or two tadpoles were carried by male nurse frogs, but free-living larvae were not found. The call is a short, surprisingly loud and far-carrying, insect-like buzz influenced by ambient temperature. Rising temperature causes pulse rate to increase and call length to decrease; the second effect probably reinforces the first, since there seems to be an independent tendency for short calls to be pulsed faster than long ones. The call of a related species, Dendrobates opisthomelas, differs even at the same temperature in duration, pulse rate, and dominant frequency. Defensive skin secretions of Dendrobates bombetes contained 22 piperidine alkaloids in the two sampled populations, with 15 or 17 compounds each. Interpopulational variation is partly due to minor differences in degree of saturation of some compounds, and the gas chromatographic profiles are therefore much alike even though the shared-alkaloid value is low (67%). Three new alkaloids form at least a natural subgroup in the pumiliotoxin-A class, to which they are tentatively assigned in spite of anomalous mass spectra; a fourth new alkaloid is placed in the pumiliotoxin-C class"--P. [1]

Poison-dart frogs

p. 175-262, 2 leaves of plates : ill. (some col.), maps ; 26 cm.Includes bibliographical references (p. 259-262)."Studies in progress reveal at least three novel classes of toxic alkaloids in skin secretions of Neotropical dendrobatid frogs. Batrachotoxins are characterized by a steroidal ring structure; those batrachotoxins having a pyrrole carboxylate substituent are among the most toxic of nonprotein poisons. Pumiliotoxins are less toxic and poorly known, but pumiliotoxins A and B appear to have a bicyclic ring system with differing side chains; pumiliotoxin C is a simple cis-decahydroquinoline. Histrionicotoxins have an unusual spiro-ring system and both 4-carbon and 5-carbon side chains, on the cyclohexane and piperidine rings, respectively. Structures are uncertain for other alkaloids of lower molecular weight, but some appear structurally related to pumiliotoxins and others to histrionicotoxins. Methods of study include thin-layer chromatography, gas chromatography, electron impact and chemical ionization mass spectrometry, and quantitative mass spectrometry. Combined gas chromatography-mass spectrometry gives reproducible results for small-sample taxonomic comparisons of frogs containing pumiliotoxins, histrionicotoxins, and similar alkaloids. Limitations of molecular data in taxonomic and evolutionary studies are considered. Biochemical and other variation are analyzed in Dendrobates histrionicus, a rain-forest frog of western Colombia and northwestern Ecuador. Sexual dimorphism is slight, and geographic variation in body size appears correlated with climate. There are geographic differences in relative tibia length and in escape behavior. Interpopulational differences in color and color pattern are extreme, and intrapopulational variation also may be considerable. Most colorations are thought to be aposematic, but highly variable frogs of one population seem cryptically colored. Dendrobates histrionicus elaborates histrionicotoxins and lower molecular-weight alkaloids; one population sample had trace amounts of a higher molecular-weight compound, tentatively identified as pumiliotoxin B. Southern populations produce large amounts of histrionicotoxins and lesser amounts of lower weight alkaloids, a situation reversed in most northern populations. Individual populations have 8-10 of 19 alkaloids detected by gas chromatography-mass spectrometry. Alkaloid similarity comparisons show that most populations share more compounds with near than with distant populations; a geographically intermediate population shares as many or more alkaloids with distant as with neighboring populations. Analysis of geographic variation in skin toxins supports the notion of conspecificity of most histrionicus-like frogs, but different spectra of toxins revealed two additional sibling species. These new species resemble D. histrionicus in morphology (including absence of omosternum), vocalizations, and type of male aggressiveness; and their color patterns, although distinctive, are approached in the variation of histrionicus. Dendrobates lehmanni, new species, lacks histrionicotoxins and produces pumiliotoxins and other alkaloids not detected in histrionicus; it is a black frog with crossbands of vivid orange or orange-red. Dendrobates lehmanni was known for years only from specimens sold in the animal trade, but its habitat is traced to a restricted area of montane forest in the Río Anchicayá drainage of the western Andes, Department of Valle, Colombia. Dendrobates occultator, new species, shows greater biochemical resemblance to histrionicus, but shared alkaloid similarity values are relatively low, and it produces significant amounts of pumiliotoxins and only two kinds of histrionicotoxins (5-7 kinds in populations of histrionicus). Dendrobates occultator is a red-backed frog with yellow lateral spots; it occurs in the Pacific lowlands, in the upper Río Saija drainage, Department of Cauca, Colombia, where it is sympatric with a population of histrionicus. Both lehmanni and occultator may have speciated from geographical isolates of histrionicus; it is suggested that some character divergence might have occurred after the range of occultator was rejoined with the parent species. Dendrobates viridis, new species, is also described, as it occurs sympatrically with the other two new species and evidently has an extensive range in Pacific-side Colombia, along the western flank of the Andes. It is a miniature, uniformly green frog, whose skin secretions include pumiliotoxins. Species of Dendrobates in Central America and northwestern South America seem characterized by either of two kinds of vocalizations, which correlate with calling behavior and type of aggressiveness. Buzz calls are a nearly uniform series of pulses, which are produced too fast for resolution by the human ear but which can be directly visualized on sound spectrograms made with a wide-band filter. Buzz calls are given by D. auratus and D. minutus (and 'Phyllobates' espinosai), species that call relatively infrequently and which seem relatively unaggressive. Chirp calls are trains of harsh, poorly modulated notes, in which pulses are produced too fast for resolution on wide-band sound spectrograms. Chirp calls are given by D. granuliferus, D. histrionicus, D. lehmanni, D. occultator, D. pumilio, and D. speciosus -- all of which are characterized by nearly incessant calling from perches, and by pronounced male aggressiveness related to territorial defense. Geographic variation in normal and aggressive calls suggests that D. pumilio may actually be a composite of two species, but biochemical and other variation have yet to be investigated"--P. 177-178

Poison frog

24 p. : ill. ; 26 cm.Includes bibliographical references (p. 23-24)."Dendrobates silverstonei, new species, is a distinctive orange-and-black or red-and-black frog discovered in the 1940s, as a consequence of road construction across the Cordillera Azul on the Amazonian flank of the Peruvian Andes. A colored photograph of a nurse frog, engaged in the dendrobatid trait of tadpole carrying, was widely promulgated in the multilingual editions of Cochran's Living amphibians of the world, as well as in other popular works. The species is now removed from consideration with Phyllobates bicolor, the only frog with which it has been previously confused or seriously compared. The newly named silverstonei belongs to a group containing the type species of Dendrobates rather than to the demonstrably monophyletic group containing the type species (bicolor) of Phyllobates. The color pattern of D. silverstonei is a convergent autapomorphy showing only the most superficial resemblance to that of P. bicolor, and silverstonei lacks the potent batrachotoxin alkaloids of Phyllobates. Skin secretions contain small amounts of alkaloids, mainly of the pumiliotoxin-A class. Dendrobates siliverstonei is placed tentatively in a species group containing D. trivittatus, because of similarities in morphology and natural history. The highland Dendrobates silverstonei (above 1300 m. elevation) shares various biological attributes with the widespread lowland D. trivittatus (below 800 m.), and their nearly identical songs are described as retarded trill calls, the fourth class of dendrobatid vocalizations to be defined. Both species are wary and usually quick to hide, and both seem to have some preference for edge situations. Similar-sized clutches of eggs of each species have been found in dead leaves on the forest floor, with male frogs in attendance. Tadpoles are carried to terrestrial water by the male nurse frog. There is interpopulational variation in the color pattern of D. silverstonei, and perhaps also in the ontogenetic development of the pattern. Geographic variation is likely to be extensive if the species proves to occupy a large range in the montane forest of Cordillera Azul"--P. [1]