Dorsal Pores Research Articles

Cyathodium bischlerianum, sp. nov.(Marchantiales) a New Species from the Neotropics

Abstract Cyathodium bischlerianum is described as a new Neotropical species from Panama. The species is distinguished by its slender, delicate thallus; a prominent dorsal pore at base of involucre; monoicous condition with 1–2 archegonia per involucre, and male receptacles on sides of thallus; sporophytes without operculum; cells of upper third of capsule with bar-like thickenings; elaters attached to base of capsule wall with 3–4 bands; and spinose-bulbose spores. This species resembles the Asiatic C. aureonitens in spore ornamentation, but its monoicous condition, lack of operculum, naked involucre, and ornamentation of upper capsule cells separate it from its Asiatic relative. It is also related in morphology, sexual condition, and spore ornamentation to C. cavernarum.

The Class Asteroidea (Echinodermata): Fossils and the Base of the Crown Group

SYNOPSIS. Because of limited research, a generally accepted hypothesis has not emerged for the phylogeny of the Asteroidea. The fossil record is a potential source of needed data, although fossil asteroids are rare, and they tend to be poorly preserved. Emphasis in the taxonomy of both recent and fossil asteroids has been on characters visible from the exterior, and paleontologists have sought to fit even the most ancient (i.e., Ordovician) specimens into taxonomic ordinal schemes devised for recent asteroids. Animal form and arrangement of body wall ossicles of Paleozoic asteroids can be similar to those of younger species, thereby suggesting close affinities, yet ambulacral arrangements indicate clear separation of Paleozoic stem groups from the crown group. Traits taken from the ambulacral column that mark crown-group asteroids include presence of dorsal podial pores (which allowed transfer of the ampullae to the arm interior), an offset arrangement of ambulacrals on the adambulacrals, and increased complexity of the articulation structures between ambulacrals and adambulacrals. Transfer of ampullae to the arm interior provided protection and more space for ampullae within the arm, as well as space within the furrow and between the ambulacral and adambulacral ossicles for elaboration of the soft tissues that enhance arm motion.

Redescription of Hapalotrema mistroides (Monticelli, 1896) and Hapalotrema synorchis Luhman, 1935 (Digenea: Spirorchidae), with Comments on Other Species in the Genus

Hapalotrema mistroides (Monticelli, 1896) Stiles and Hassall, 1908 and Hapalotrema synorchis Luhman, 1935 are redescribed using specimens from the loggerhead turtle. Caretta caretta (L.). The redescription of H. mistroides is based on specimens collected by Looss and described as Hapalotrema constrictum Leared, 1862 and renamed Hapalotrema loossi Price, 1934, which is now considered a junior synonym of H. mistroides. Hapalotrema orientalis Takeuti, 1942 is considered a junior synonym of Hapalotrema synorchis. The redescriptions are consistent with the originals but provide an unreported range of variation while adding new information about the reproductive systems. Reexamination of Hapalotrema dorsopora Dailey, Fast, and Balazs, 1993 confirms the presence of a reproductive system typical for the genus and the absence of a dorsal genital pore; therefore, H. dorsopora is reduced to a junior synonym of Hapalotrema mehrai Rao, 1976. Four valid species of Hapalotrema are recognized: H. mistroides. H. synorchis, H. postorchis, and H. mehrai, and a key to the species is provided.

Two Lepotrema Ozaki, 1932 species (Digenea: Lepocreadiidae) from marine fishes from the southern Great Barrier Reef, Queensland, Australia

The genus Lepotrema Ozaki, 1932 is revived and redefined. Its main diagnostic characters are the dorsal excretory pore, the muscular development of the distal metraterm and the trilobate ovary. It is considered to contain five species, to which a key is given. Lepotrema clavatum Ozaki, 1932 is briefly redescribed from Amanses scopas and Sufflamen chrysopterus, and L. canthescheni n. sp. is described from Cantheschenia grandisquamis, based on material from the southern Great Barrier Reef. L. canthescheni is distinguished by its vitelline and uterine distribution. The other three recognised species are: L. adlardi (Bray, Cribb & Barker, 1993) n. comb., L. incisum (Hanson, 1955) n. comb. and L. xanthichthydis (Yamaguti, 1970) n. comb., all three having originally been placed in Lepocreadium.

Ultrastructure of the Coeloms of Auricularia Larvae (Holothuroidea: Echinodermata): Evidence for the Presence of an Axocoel.

A hallmark feature of echinoderm larvae is the development of the left anterior coelom. This coelom, called the axohydrocoel, consists of the morphologically distinct, but undivided, left axocoel and hydrocoel. The axocoelic portion forms a duct that opens to the exterior via a pore on the dorsal surface of the animal. Holothuroid larvae are thought to lack an axocoel, but develop an anterior coelom, duct, and pore that are regarded as parts of the hydrocoel. New ultrastructural data, however, show that holothuroid auricularia larvae possess an axocoel and hydrocoel united together into an axohydrocoel. During development the anterior coelom consists of an interconnected left somatocoel, hydrocoel, and axocoel. The left somatocoel separates from the axohydrocoel and subdivides into left and right somatocoels. The somatocoels and hydrocoel region of the axohydrocoel are lined by a monociliated mesothelium having characteristics of transporting epithelia. The axocoel epithelium, like that of asteroid larvae, is composed of mesothelial podocytes. A duct connects the axocoel directly to the open dorsal pore and is lined with a columnar transporting epithelium. The occurrence of a specialized podocyte-lined cavity between the surface pore and the hydrocoel in echinoderm larvae is indicative of an axocoel. That similar structures occur in auricularia larvae supports the identification of an axocoel in holothuroids.

Sex pheromone gland of the female tiger moth Holomelina lamae (Lepidoptera: Arctiidae)

Airborne sex pheromone from the female arctiid moth Holomelina lamae originates from a pair of internal glands located dorsally at the female's abdominal tip, above the ovipositor. Each gland opens externally to a dorsal pore, with both pores being situated near the junction of abdominal segments 8 and 9. The lumen of each gland is lined by cuticle with a profusion of spines; these presumably prevent collapse of the tubes. Beneath the cuticle is a layer of pear-shaped epithelial cells. In ultrastructural examination, these cells are characterized by microvilli apically, a large nucleus and numerous organelles in the central region, and a highly convoluted membranous area basally. The tubular gland structure with internal spines provides a reservoir for sequestering the several micrograms of pheromone found in this small moth. It is suggested that the function of these spines is in pheromone emission.

The myrmecophilous organs of larvae of the small blue,Cupido minimus(Lepidoptera; Lycaenidae)

Larvae of the lycaenid butterfly Cupido minimus have been examined using scanning electron microscopy following critical-point drying. They were found to possess both dorsal organs and pore cupolae, organs associated with myrmecophily. These results are compared with those of earlier authors and their significance discussed.

Gongylonema aegypti n. sp. (Nematoda: Thelaziidae) from Egyptian rodents

A new species of spiruroid nematode,Gongylonema aegypti, is described from two rodents,Mus musculus andGerbillus gerbillus, from Egypt.G. aegypti is distinguished from closely related species by the size of the spicules and gubernaculum, the absence of cuticular bosses in males, and the size of the egg. SEM studies suggest that the generic diagnosis ofGongylonema should be amended to include the presence of a dorsal pore on the cephalic plate and the presence around the buccal cavity of three triangular teeth (not lips) and two sclerotized plates or interlabia. ac]19850414

Species of Discolaimus (Nematoda: Dorylaimoidea) From Australia

Five species of Discolaimus collected from Australian mallee soils are described: D. major, D. texanus and three new species. In each species the lip region is an expanded, saucer shaped disc with distinct rim, divided by grooves into six sectors on the anterior surface, and variously lobed on the under surface. D. agricolus n. sp., monosexual, L = 1.30-1.73 mm, V = 45-48, odontostyle = 21-23 μm, has a multi-lobed lip region similar to D. major and an anterior oesophagus of uniform diameter throughout. D. silvicolus n. sp., monosexual, L = 1.16-1.89 mm, V = 51-53, odontostyle 20-22 μm, has a distinctively lobed lip region and prominent sheath around the basal oesophageal expansion. D. elegans n. sp., monosexual, L = 1.11 to 1. 20 mm, V = 50-53, odontostyle 14-15 μm, has three rows of lateral body pores. In D. major, D. agricolus and D. silvicolus a group of large cells of unknown function is present in the cardiac region. Two subventral longitudinal grooves in the odontostyle and numerous ventral and dorsal body pores are present in all five species.

Three Xiphinema Species From Papua New Guinea and the Solomon Islands (Nematoda: Longidoridae)

Xiphinema papuanum n. sp. is described from Papua New Guinea. It is compared with X. mammillatum S. Stekhoven & Teunissen, 1938 which it closely resembles but from which it can be differentiated by tail length, vulva position, number of ventral and lateral body pores, position of the most anterior dorsal and ventral body pores, thickness of the cuticle on dorsal side of tail and length of the pars dilatata uteri in mature females. The new species is also compared with X. basilgoodeyi Coomans, 1965 from which it can be distinguished, among other things, by the differently shaped and shorter tail, larger number of ventral and lateral body pores, and differences in tail shape in juvenile stages. A female and the four juvenile stages of X guirani apud Lamberti & Bleve-Zacheo, 1979 are described and figured, also from Papua New Guinea, and a male of X. ensiculiferum (Cobb, 1893) is described from the Solomon Islands.

Earthworm bioluminescence: Comparative physiology and biochemistry

1. 1. The comparative physiology and biochemistry of twelve species of bioluminescent earthworms from six genera (Diplocardia, Diplotrema, Fletcherodrilus, Octochaetus, Pontodrilus and Spenceriella) from the U.S., Australia and New Zealand indicated considerable similarity in the mechanism of bioluminescence. 2. 2. With the exception of Pontodrilus bermudensis where the fluid is exuded from the mouth, all species exude bioluminescent coelomic fluid from their dorsal pores. 3. 3. Microscopic observation, isolation of active particulate fractions from seven species and comparison to the previous study of D. longa (Rudie & Wampler, 1978) suggests that the site of luminescence is the free chloragogen cell. 4. 4. The emission spectra (eight species) were broad, unimodal with maxima ranging from 500 nm to greater than 570 nm. 5. 5. The spectral and biochemical data supports the hypothesis that earthworm bioluminescence involves the reaction of hydrogen peroxide with N- isovaleryl-3-aminopropanal or its close analog, and that spectral distribution is determined by the luciferase or other luciferase-association components.

Observations on the fine structural changes associated with schizogony and gametogony in Eimeria tenella.

Changes associated with schizogony and gametogony in Eimeria tenella have been studied by means of electron microscopy.In infections of E. tenella both small and large schizonts are formed, and in both cases merozoites are developed by a surface ‘budding’ mechanism. The final severance of the merozoite from the schizont appears to give rise to the dorsal pore of the merozoite. Newly formed merozoites contain structures which are absent in the mature organism.Early in microgametogony the nucleus of the microgametocyte divides repeatedly to produce a number of smaller nuclei which migrate peripherally in the cell. The chromatin aggregates into the peripheral part of each nucleus, which then elongates to form the nucleus of the of microgamete. That part of the gametocyte nucleus which is devoid of chromatin, probably gives rise to the perforatorium and three flagella of the gamete. Residual material is left in the gametocyte cytoplasm in the form of a gametogenic cyst.‘Wall-forming’ bodies are present in the earliest macrogametocyte and ‘dark bodies’ are developed later. After fertilization these bodies migrate to the periphery of the zygote. In E. tenella the oocyst wall is trilaminate. The limiting membrane of the zygote separates from the cell to become the outermost membrane of the cyst wall. The middle layer of the cyst wall is developed from the ‘dark bodies’, and the ‘wall forming’ bodies give rise to the inner layer of the oocyst wall.

The Role of the Coelomic Fluid in the Movements of Earthworms

ABSTRACT A short review is given of the coelom and of its morphological relations in the earthworm. The arrangement of the intrinsic muscles in a typical septum is described. Four main sets of muscles are recognized: viz. radial muscles, circular muscles, oblique muscles, and the sphincter around the ventral foramen. It is suggested that the function of the radial, circular and possibly of the oblique muscles is to control bulging of the septa, and so serve to localize differences in pressure in the coelomic fluid. Normally, in active worms, the sphincter of the ventral foramen is contracted and forms an effective barrier to the passage of fluid from one coelomic compartment to the next. This was verified experimentally and by X-ray photography. A series of measurements of the pressure in the coelomic fluid in different regions of active worms was recorded by means of a capillary manometer and by the use of a spoon-gauge apparatus. Manometric measurements showed the average pressure in the anterior third of the body to be 16.0 cm. water and in the tail region to be 8.0 cm. water. The corresponding figures obtained with a spoon gauge were 13.5 and 8.5 cm. water. The pressure in narcotized worms is zero. These results are discussed, and it is pointed out that the manometer readings suffer from the disadvantage of failing to show the rapid fluctuations in pressure which occur during wriggling movements of the worms. It is calculated from these pressure readings that a worm can exert a forward thrust equivalent to forces of between 1.5 and 8.0 g. These figures agree well with those obtained by Gray & Lissman by the use of a special torsion balance. The burrowing movements of earthworms are briefly described. It is shown that the sphincters of the dorsal pores and of the nephridiopores do not normally allow of the escape of coelomic fluid, and will withstand a pressure well outside the normal range.

Memoirs: Spolia Bermudiana

1. Several stages of a new type of Auricularia (A. bermudensis n.sp.) are described. When fully formed it resembles A. nudibranchiata in the foliation of its ciliated bands and appendages, but is distinguishable by many structural features and in becoming full-grown at less than half the size (<4 mm.). 2. The usual arms are present, adnate to the body, as well as a special ‘strap-shaped process’ with directive functions. They support a system of gutters plainly subservient to food-collection. The terms ‘field’ and ‘sulcus’ (with the diminutive ‘sulculus’) are proposed for the raised and depressed areas of Dipleurulae in general. 3. The so-called ‘larval nervous system’ is claimed to be simply a pair of ciliary organs subservient to the feeding process and comparable to an outer pair of adoral bands (‘oro-lateral bands’). 4. The rectum is in line with the stomach and the anus subterminal, but the ileum is reduced to a dorsal pore, and the part of the rectum adherent to the stomach is a large ventral pouch comparable to that described in A. nudibranchiata by Chun, whose account is confirmed. 5. The author has re-examined the original specimens of A. antarctica and denies the existence of the paired ‘intestinal pouches’ described in this species and in A. nudibranchiata by MacBride. 6. The anterior enterocoel in the younger specimens is unique in possessing two long, tapering, bilaterally symmetrical ‘horns’, functionally dilated. Hydrocoel and water-tube arise from the left horn. Eventually the right horn undergoes self-amputation and is absorbed. At full growth the persistent left horn, still of unusual length, acquires antler-like points and branches, as in A. nudibranchiata. 7. The significance of the new features is discussed in comparison with Tornaria and Planktosphaera.

Coccidae from the Seychelles

Adult female pyriform, broadest across the meso- and metathorax; cephalothoracic area rounded in front, slightly contracted behind, where there is a well-defined transverse grove; abdomen tapering to the posterior extremity; frons and margins of thorax and abdomen with a few spiniform setae. Antennae rudimentary, each bearing a single long straight seta. Anterior spiracles with a small group of parastigmatic pores (fig. 1, A). Pygidium with a well defined, strongly chitinised, pyriform, reticulated area, the lacunae oval or round, and disposed regularly; the part posterior to the anus, very heavily chitinised, obscuring the lacunae. Circumgenital glands present, consisting of a continuous arch representing the united median andanterior lateral groups, with the posterior laterals separated by a short space; the anterior laterals show signs of being in two rows. Dorsal pores numerous, comparatively small, circular, arranged in longitudinal series on each side of the pygidium, and extending on to the margins of the abdomen (fig. 1, B). Pygidial margin with three pairs of lobes and numerous angular projections laterad, each lobe notched on the outer side; two pairs of conspicuous claviform paraphyses, each with a large separate circular knob like the dot of an i (fig. 1, C). Length, 1 mm.; greatest breadth about 0·75 mm.

On the Development of Cucumaria echinata v. Marenzeller.

On the Development of Cucumaria echinata v. Marenzeller.

Notes on Coccidae occurring in the Seychelles Islands, with descriptions of new species

The new species, described below, have been received from Mr. R. Dupont, Superintendent of Botanic Stations in the Seychelles.Aspidiotus (Chrysomphalus) ansei, sp. nov. (fig. 1).Female puparium irregularly circular or broadly ovate ; flattish or moderately convex. Very pale brownish ochreous, semitransparent ; pellicles darker, central. Diameter averaging 1·45 mm.Male puparium smaller and more distinctly ovate ; pellicle nearer one extremity. Length 1 mm.Adult female broadly rounded in front, narrowed and bluntly pointed behind. Margins of abdominal segments moderately produced. Pygidium (fig. 1) with six well developed prominent rounded lobes, the median pair indented on each side, the two lateral lobes more conspicuously indented on the outer side. Squames. long and deeply fimbriate : two in each of the median and first lateral spaces, three in the second lateral space, and three beyond the outer lateral lobe, followed immediately by a stout marginal prominence, beyond which the margin is slightly cristate for a short distance. Spines few, small and inconspicuous. Paraphyses, four on each side, elongate, conspicuous. Anal orifice near the extremity. Circumgenital glands in four groups: upper laterals with 3 to 4 pores, lower laterals with 2 to 3. Oval dorsal pores in two series on each side. Numerous long slender ducts communicating with the dorsal and marginal pores. Length, 1 mm.

VII. On the cœlomic fluid of lumbricus terrestris in reference to a protective mechanism

Since the publication of Claparède’s classical memoir on the earthworm, numerous writers have contributed to advance our knowledge of the morphology of this animal. In England, the writings of Ray Lankester, W. B. Benham, and F. E. Beddard have considerably increased the literature of the subject; but, with the exception of incidental references to function, the papers hitherto published have dealt chiefly with the morphology, taxonomy, or geographical distribution of the animal. Darwin long ago collected the observations of Claparède and other older authorities on the physiology of the earthworm, in his work on Vegetable Mould, which consists mainly of his own observations on the habits of the animal. An article “On the Retractile Cilia in the Intestine of Lumbricus terrestris ,” by M. Greenwood, in the ‘Journal of Physiology,’ vol. 13, is, I think, the only systematic contribution in English to our knowledge of the physiology of the earthworm in recent years. The present communication contains the results of an investigation into the functions of the cœlomic fluid. The greater part of the research consists, therefore, of a detailed study of the morphology and physiology of the amœboid cells, which form the most important contents of the cœlom. But in the course of my observa­tions, I was led to investigate some of the chemical characters of the cœlomic fluid, and also to examine certain other structures, such as the skin and the dorsal pores, which form, with the cœlomic fluid, a very remarkable protective mechanism.