THE NEAR-SPINELESS TRACHELOMONAS GRANDIS (EUGLENOPHYCEAE) SUPERFICIALLY APPEARS SPINY BY ATTRACTING BACTERIA TO ITS SURFACE1,2

Trachelomonas grandis Singh has a mucilaginous, highly porous mineralized lorica (envelope) generally without ornamentation except occasionally for a few short, tapered, anterior or posterior spines. However, as our first cultures of this species aged, rod-shaped structures appeared on the loricas. That these surface projections were bacteria was determined by scanning and transmission electron microscopy. The bacteria, 2-6 μm long with rounded apices, were oriented perpendicular to the exterior lorica surface and were attached on one end by apically produced tie-down fibers. The bacteria also secreted fibers over their entire surface, forming a network between them that collapsed during specimen preparation for scanning electron microscopy. The density of the surface bacteria increased with time until the lorica took on a “spiny” appearance superficially similar to lorica extensions of algal origin. In mature algal specimens, an estimated 1200-1800 bacteria per lorica occurred as a monolayer, the maximum number related to the surface area of the lorica available for bacterial colonization. The bacteria, always motionless while attached, showed putative evidence of budding. Fission formed short chains of up to three cells on the lorica. Our cultures maintained this association for 8 years (1972-1979). However, cultures ordered for further study in the past year have failed to develop loricas with more than just a few bacterial cells, and most have none.     

Ultrastructural features of the tegumental surface of a new metacercaria, Nematostrigea sp. (Trematoda: Strigeidae), with a search for potential taxonomically informative characters

The tegumental surface of a new strigeid metacercaria, Nematostrigea sp., which is a parasite of the freshwater fish Channa gachua (Hamilton) in central Vietnam, is described for the first time using scanning (SEM) and transmission (TEM) electron microscopy. In addition to the general tegumental surface in various parts of the body, details of the surface of the suckers, lappets and holdfast organ are presented, as are variations in the form and distribution of the body spines. As good taxonomic criteria are few in diplostomoid metacercariae at both specific and generic levels, a number of the ultrastructural features revealed may prove to represent taxonomically informative characters. These include the presence of: two rings of dome-shaped papillae localised at different levels on the rim of the oral sucker, a single ring of ciliated papillae on the inner margin of the ventral sucker and a band of dome-shaped papillae along the lateral margins of the broad body-fold in the ventral forebody; an unarmed oral sucker and anteroventral surface of the forebody, although the latter bears protuberant secretory pores; an armed ventral sucker covered by six-pointed spines, except on its rim; multi-pointed spines along the dorsal and ventral sides of the forebody, with the number of their teeth increasing posteriorly; multi-pointed spines on the forebody which gradually transform into single-pointed, more widely distributed spines on the hindbody, disappearing completely at posterior end of the body; the surface of the lappets with a particular distribution of pores leading to three types of secretory glands and three topographical modifications (areas where the surface is smooth, bears digitiform processes or bears recurved, dagger-shaped spines); and the surface of the holdfast organ which is covered with densely packed, straight or slightly curved, simple spines on its lateral surface but is smooth medially.     

OBSERVATIONS ON THE CHARACTERISTICS OF THE LEMMA AND PALEA OF THE LATE CENOZOIC GRASS PANICUM ELEGANS

Scanning electron microscopy (SEM) was used to study the surface features of the anthoecia (fertile lemma and palea) of Panicum elegans Elias from the Late Cenozoic deposits in Ellis County, Kansas. Examination of the lemma revealed a well developed germination lid, irregularly arranged, simple, rounded papillae and a crescent-shaped scar of attachment. The presence of a germination lid indicates that this structure has been present in some members of the Gramineae since at least the Late Miocene-Early Pliocene. Evidence is presented which contradicts current ideas regarding the distribution of the germination lid in extant Gramineae. The surface of the palea is characterized by simple, rounded papillae spaced in regular rows. The arrangement and form of these papillae are like that present in some modern Dichanthelium. Both the epidermises of the lemma and palea are composed entirely of long cells with strongly sinuous, interlocking cell walls. The pattern of cells on the lemma indicates that the systematic placement of Panicum elegans is correct.     

Two New Species of Rotifera from China

Two new rotifera species, Brachionus huangi n. sp. and Lecane chinesensis n. sp. are described and illustrated from different localities in China. The main distinguishing taxonomic features of B. huangi are three pairs of apical spines, a pair of symmetrical caudal spines and a wide caudal projection. For L. chinesensis, the main characteristics are the two-sided small extentions of the foot pseudosegment, the long and innercurved apical spines and ventral lorica anteriorly narrower than the dorsal one.     

A NEW GENUS OF PROTOSTELIDS SHOWING AFFINITIES WITH CERATIOMYXA

A new genus and species of the Protosteliida (Mycetozoa), Ceratiomyxella tahitiensis, was isolated from dead plant material—var. tahitiensis from Tahiti and var. neotropicalis from Brazil and Colombia. The sporocarps have deciduous spores borne singly on slender hollow stalks; zoocysts with anteriorly flagellate planonts are produced. The trophic stage is comprised of uninucleate to plurinucleate amoeboid cells and reticulate plasmodia; the uninucleate cells become flagellate in water. The prespore cells and spores are plurinucleate. Sexuality has not been demonstrated. Var. tahitiensis has globose spores and produces its zoocysts just after spore germination, whereas var. neotropicalis has subglobose spores and forms zoocysts later in the life cycle. The species is thought to show phylogenetic relationships with Ceratiomyxa, which was recently transferred to the Protosteliida by Olive.     

THE EVOLUTION OF SELF-POLLINATION IN GRANITE OUTCROP SPECIES OF ARENARIA (CARYOPHYLLACEAE). IV. CORRELATED CHANGES IN THE GYNOECIUM

Intraspecific variation in gynoecial characters was analyzed by SEM for nine populations of Arenaria uniflora, a winter annual endemic to rock outcrops in the southeastern United States. Style lengths in self-pollinating populations, formerly called A. alabamensis, were significantly shorter than in outcrossing populations, and style length showed a very strong correlation (r = 0.97) with outcrossing potential as assessed by degree of protandry. Selfers were also characterized by the production of fewer but longer stigmatic papillae. Papillae extended to the base of the style and diverged from all sides. Outcrossers had longer styles with dense but short papillae, mostly restricted to the upper surface of the style and lacking at its base. Styles also were observed to curl downward in outcrossers. These fine-scale changes appear to enhance the effectiveness of plants as either outcross-pollen or self-pollen receivers.     

Surface ultrastructure of the plagiorchid trematode Glossidium pedatum Looss, 1899 from bagrid fish in Egypt

The present study concerned the morphology and surface ultrastructure of a plagiorchid, Glossidium pedatum, from bagrid fish of the river Nile in Egypt. Adult G. pedatum have an elongate body, tapered towards the anterior and posterior ends. Their oral sucker is small, sub‐terminal and rounded, measuring 0.200 mm in diameter. Sensory papillae around the oral sucker usually occur in small clusters of three to eight each. The ventral sucker is large, situated at the anterior end of the second third of the body, 0.299 mm in diameter, and is surrounded by three pairs of sensory papillae. Both suckers have rounded rims covered by tegumental spines. On the anterior part of the ventral surface of the body tegumental spines are small, pointed and closely spaced. A small triangular area of tegument anterior to the ventral sucker is devoid of spines. Tegumental spines on the mid‐region of the body slightly increase in size and number, especially towards the lateral aspects and posterior to the ventral sucker. Towards the posterior end of the body the spines progressively decrease in both size and number. The dorsal side exhibits similar surface features but the spines are less numerous and slightly smaller.     

Morphological variation of <Emphasis Type="Italic">Keratella cochlearis</Emphasis> (Gosse) in Myanmar (Burma) in relation to zooplankton community structure

Keratella cochlearis was present in 27 of 35 water bodies sampled in Myanmar, and was the most abundant rotifer in 10. Measurements of lorica length and posterior spine length from 20 localities showed that posterior spine length varied both with lorica length and with the composition of the crustacean zooplankton. Long spines were associated with dominance by Heliodiaptomus. The shortest spines were found in samples dominated by cladocerans or cyclopoid copepods. Posterior spine length was positively correlated with the number of diaptomid copepods. Forms without posterior spines were found in 17 localities. The lorica lengths of these spineless forms were generally similar to those of co-occurring spined forms (r = 0.68), but in a few samples the loricas of the spineless forms were significantly larger. These larger forms are similar to the ‘aspina’ forms recently recognised in the River Thames in England. These samples were dominated by cladocerans or cyclopoid copepods. In one locality spineless forms were found without spined forms. The crustacean zooplankton in this locality was also dominated by cladocerans. Guest editors: S. S. S. Sarma, R. D. Gulati, R. L. Wallace, S. Nandini, H. J. Dumont & R. Rico-Martínez Advances in Rotifer Research     

EPIDERMAL FEATURES AND SILICA DEPOSITION IN LEMMAS AND AWNS OF ZIZANIA (GRAMINEAE)

In four species of Zizania (Gramineae: Oryzeae) epidermal features of pistillate and staminate lemmas, paleas, and awns were studied by scanning electron microscopy (SEM) and energy dispersive X-ray analysis. Features observed were silica bodies, siliceous papillae, pitted siliceous papillae, stomata, microhairs, and prickle hairs. Staminate lemmas have all of these features. Pistillate lemmas have silica bodies and prickle hairs, lack stomata, and differ among species in occurrences of microhairs and siliceous papillae and pitted siliceous papillae. Awns of pistillate lemmas have silica bodies, prickle hairs, microhairs, and stomata; therefore, they possess a more complete set of features than their attached lemmas. Shapes of silica bodies on pistillate lemmas differ among species. A taxonomic key based on SEM observation of pistillate lemmas separates the four species by the shapes of silica bodies, arrangement of prickle hairs, and occurrences of microhairs and siliceous papillae. The main silica-containing structures are silica bodies, siliceous papillae, pitted siliceous papillae, and to a lesser extent prickle hairs. Pitted siliceous papillae with circular raised rims are formed by collapse or exfoliation of the tops of siliceous papillae; these have not been previously described in grasses. Comparison of epidermal features in the lemmas and leaves of Zizania shows that the former lack three kinds of nonsilicified papillae and epicuticular wax that are present on the latter but the lemmas have siliceous papillae and pits that are absent in leaves.     

SOME EPIDERMAL CHARACTERISTICS OF PALEAS OF DICHANTHELIUM,PANICUM, AND ECHINOCHLOA

The apical portion of paleas of the perfect (upper) floret of 11 species of Dichanthelium, 10 species of Panicum, and one species of Echinochloa were examined with a scanning electron microscope. The surfaces of the Dichanthelium palea tips uniformly had simple, rounded papillae, widely spaced in regular rows, whereas the palea tips of most Panicum species had irregularly arranged, compound or aggregated papillae. Unusual epidermal features were observed in P. obtusum, P. hians, and P. hemitomon. The Echinochloa crusgalli palea surface exhibited a pattern of papillae or spicule development similar to that of P. hians. Transverse sections of Dichanthelium palea showed the papillae to be little if at all thickened. An electron beam x-ray microanalysis indicated a high concentration of silicon in the papillae.     

Ultrastructure of the ventral sucker of Schistosoma mansoni cercaria

The ventral sucker of Schistosoma mansoni cercaria is a cupshaped structure that is attached to the ventral surface of the organism by a homogeneous connective tissue that surrounds the acetabular glands. The sucker consists of an extensive complex of circular and longitudinal muscles. The longitudinal muscles extend outwoard in a radial pattern to form the cup of the organ. Intermingled with the muscles are nerve bundles and subtegumental cells (cytons). Dendritic nerve fibers connect to sensory papillae which are found on the surface tegument. Two types of sensory papillae are present: a commonly found unsheathed uniciliated papilla, and a previously unidentified tegumental encapsulated structure. Tegument with spines covers the ventral sucker, although the tegumental encapsulated sensory papilla lacks spines. © 1995 Wiley-Liss, Inc.     

Surface ultrastructure of juvenile and adult Acanthoparyphium tyosenense (Digenea: Echinostomatidae)

The tegumental ultrastructure of juvenile and adult Acanthoparyphium tyosenense (Digenea: Echinostomatidae) was observed by scanning electron microscopy. One- to 3-day-old juveniles and 10-day-old adults were harvested from chicks experimentally fed metacercariae from a bivalve, Mactra veneriformis. The juvenile worms were minute, curved ventrally, and had 23 collar spines characteristically arranged in a single row. The lips of the oral sucker had 7 single aciliated sensory papillae and 4 grouped uniciliated sensory papillae. The ventral sucker had 25 aciliated round swellings on its lip. The anterolateral surface between the 2 suckers was densely packed with tongue-shaped tegumental spines, and the ventral surface just posterior to the ventral sucker was covered with peg-like spines. Retractile, peg-like spines were seen on the anterolateral surface, whereas scale-like spines with round tips and broad bases were sparsely distributed posterior to the ventral sucker. The cirrus was characteristically protruding and armed with minute spines. The surface ultrastructure of A. tyosenense was unique, especially in the number and arrangement of collar spines, shape, and distribution of tegumental spines and in distribution of sensory papillae.     

Envelope formation and structure in the Euglenoid genus Trachelomonas

Ultrastructural details of envelope formation are described comparatively for several species of the genus Trachelomonas. The first-formed envelope component in T. oblonga var. punctata Prings. is an external “skin”. Next, a fibrillar layer is produced between the skin and the cell surface. Ferric hydroxide and manganese compounds are precipitated on this inner layer to form a thick envelope, species-specific in size, shape, ornamentation and collar characteristics. The original skin is then lost.

A similar sequence of events occurs during envelope formation in other species, but differences exist in the details of the process and in the texture and complexity of construction of the mature envelopes. T. volvocina Ehrenb. has a fibrillar inner layer and granular precipitation, but produces a complex three-layered envelope with a honeycombed central layer. This is compared with the superficially similar three-layered envelope of an unnamed species from a wild collection, and subtle differences in ultrastructural patterning are discussed. T. pertyi Prings. forms a two-layered spiny envelope, less highly organised than that of T. volvocina. The spiny and porous envelopes of T. hispida (Perty) Stein em. Defl., T. echinata Singh and T. lefevrei Defl. are quite different in texture, being composed of flaky material woven into a spongy matrix. The presence of large amounts of iron in the mature envelopes of all the species under study was confirmed by microanalysis in the electron microscope using X-ray spectroscopy.

Details of envelope ultrastructure are discussed in relation to taxonomy, cell metabolism, the problem of why Trachelomonas cells form envelopes when those of other euglenoid genera do not, and the problem of cell control of species-specificity of envelope characters. Electron microscopy has added considerably to our knowledge of the structural details of trachelomonad envelope formation, but it has been less successful in helping to elucidate some of the enigmas associated with this phenomenon.     

Cuticular structures of the priapulid Halicryptus spinulosus: A scanning electron microscopical study

Summary The surface anatomy and the structures lining the pharynx of Halicryptus spinulosus were examined by scanning electron microscopy (SEM). The structures were compared and contrasted with those reported for other priapulids, particularly those features previously studied with SEM. Buccal papillae and pharyngeal teeth of two types were described. Surface structures observed with SEM were: scalids, abdominal setae, anal papillae, posterior warts and ring papillae. The latter three structures are unique among described priapulids. The anal papillae are composed of several rounded, perhaps pedunculate, structures; the posterior warts are composed of mitriform structures in close association with columnar structures. Both are located in separate depressions in the posterior integument. The ring papillae occur on the annuli close to the posterior end. Halicryptus spinulosus was previously thought to lack these structures.     

Surface ultrastructure of Heterophyes nocens (Trematoda: Heterophyidae).

The surface ultrastructure of Heterophyes nocens (Trematoda: Heterophyidae) was studied by scanning electron microscopy(SEM). The adult worms were recovered from experimentally infected cats and from a naturally infected patient. They were leaf-like, ventrally concave, and ovoid or pyriform in shape. Ciliated knob-like sensory papillae (type I) were observed in single or grouped forms on and around the oral sucker, whereas non-ciliated round swellings (type II papillae) were seen on the lip of the ventral sucker. The tegumental spines around the oral sucker were 5-9 pointed, whereas those between the two suckers were 12-17 pointed. Ventrolaterally, three groups of 5-6 type I papillae were located between the oral and ventral suckers, with single ones alternating between them. The genital sucker was protruded or depressed, depending on the contraction state of the flukes, and the gonotyl spine number ranged 50-60. The number of tip points of tegumental spines was decreased posteriorly; finally they became 1-3 pointed. On the dorsal surface, 4 groups of 4-5 type I papillae were symmetrically located on both lateral sides, and the shape and distribution of tegumental spines were similar to those of the ventral surface. Although the tegumental ultrastructure of H. nocens was generally similar to those of other heterophyids, the genital sucker morphology including the number of gonotyl spines and/or the distribution pattern of tegumental spines and sensory papillae were suggested to be the characteristic features of H. nocens.     

Tetrameres (Gynaecophila) aspicula n. sp. (Nematoda: Tetrameridae), a proventricular parasite of the white-faced ibis Plegadis chihi in Argentina

Tetrameres (Gynaecophila) aspicula n. sp. is described from the proventriculus of the white-faced ibis Plegadis chihi (Vieillot) (Ciconiiformes, Threskiornithidae) from Argentina. The new species is characterised by the absence of spicules, by possessing two ventral rows of extremely small spines in males, extending along the second half of body length, and by the tiny, very feebly developed postcloacal papillae. T. (G.) aspicula n. sp. is compared to the remainder of the species in the subgenus as well as to other species of Tetrameres which lack or possess feebly developed spines. The absence of spicules is a character shared with two other species in the genus, T. (G.) gynaecophila and T. (G.) deccani,from which the new species differs in body size, the arrangement of caudal papillae and the somatic spination in males. A pair of somatic papillae, previously unreported in species of this genus, was found just on or ventral to the lateral line at various regions of the body length. The homology of these structures to other paired somatic papillae described in nematodes is discussed.     

ULTRASTRUCTURE OF THE PSEUDOCAPILLITIUM AND SPORES OF THE MYXOMYCETE LYCOGALA EPIDENDRUM. LICEALES

The pseudocapillitium and spores of L. epidendrum were studied by transmission (TEM) and scanning electron microscopy (SEM). The SEM reveals that the pseudocapillitial surface is covered by bands of “wartlike” processes that alternate with non-ornamented regions. Otherwise, the pseudocapillitium is a hollow structure composed of three regions. The outer region is thin, electron dense and continuous with many irregular processes. Internal to this area is an amorphous region containing scattered electron dense material. The innermost region of the pseudocapillitium is thin, inconspicuous and usually electron dense. L. epidendrum possesses spores that are covered by a surface reticulum consisting of polygonal areas which are continuous with the outermost spore layer. The outer spore layer is thin and electron dense. The inner spore layer is an electron transparent region that contains granular or fibrillar components. Sections of spores showed a dense cytoplasm possessing most of the usual organelles along with microtubules and microbodies.     

CUTICLES OF TWO SPECIES OF ALETHOPTERIS

Specimens of Alethopteris sullivanti (Lesquereux) Schimper and Alethopteris lesqueieuxi Wagner were found in Middle Pennsylvanian coal balls from the Lovilia, Iowa and West Mineral, Kansas localities. Light microscopy and scanning electron microscopy (SEM) were used to study macerated cuticles of these two foliage types of the pteridosperm, Medullosa. The lower epidermises of both species of Alethopteris possess sunken stomata, papillae, and evidence of multicellular hairs. The upper epidermises are devoid of these features. Critical point drying and subsequent observation with SEM were used to document the structure of the multicellular hairs of A. lesquereuxi. Replicas of the lower epidermal features of an impression-compression specimen of A. sullivanti were observed with SEM and compared with the petrified specimens.     

A proposal to regard the former family Naididae as a subfamily within Tubificidae (Annelida, Clitellata)

A new species of Placobdelloides is described from crocodiles and river turtles in the Singapore Zoological Gardens. Placobdelloides stellapapillosa is three annulate, has one pair of eyes on somite I or II, six pairs of testisacs, two annuli between the gonopores, one post anal annulus, seven pairs of lobed crop caeca and 12–14 unique star-shaped papillae on the dorsal surface of each annulus. Star-shaped papillae on annulus a2 are typically larger and more pronounced than on annuli a1 and a3. Additional minute cone-shaped papillae may occur between the larger star-shaped papillae or may replace these papillae on annuli a1 and a3. Eggs and young (100–200) are attached by their posterior suckers directly to the ventral surface of the parent.