Soil microstructure in soils of the Colorado Plateau: the role of the cyanobacterium Microcoleus vaginatus

The role of the cyanobacterium Microcoleus vaginatus in cold-desert soil crusts is investigated using scanning electron microscopy. Crusts from sandstone-, limestone-, and gypsum-derived soils are examined. When dry, polysaccharide sheath material from this cyanobacterium can be seen winding through and across all three types of soil surfaces, attaching to and binding soil particles together. When wet, sheaths and living filaments can be seen absorbing water, swelling and covering soil surfaces even more extensively. Addition of negatively charged material, found both as sheath material and attached clay particles, may affect cation exchange capacity of these soils as well. As a result of these observations, we propose that the presence of this cyanobacterium may significantly enhance soil stability, moisture retention, and fertility of cold-desert soils.     

The morphology and biology of the entomophilic Thripinema fuscum (Tylenchida: Allantonematidae), and the histopathological effects of parasitism on the host Frankliniella fusca (Thysanoptera: Thripidae)

We used light and electron microscopy to detail the in vivo life cycle of the nematode Thripinema fuscum and to determine the effects of parasitism on tissues of the thrips host Frankliniella fusca. The parasitic T. fuscum female produced eggs within 4–5 days after ingress and the host haemocoele became packed with eggs and developing juvenile nematodes. Mature juveniles migrated to the hindgut and fully developed juveniles first emerged from the posterior end of the male or female F. fusca 9 days after parasitization. Parasitization induced a displacement of the host alimentary tract, an atrophy of the ovaries and fat body, and an alteration of energy and waste reserves in host tissues. Our observations reveal a specialized relationship showing that this parasite is well adapted to exploit the host digestive, reproductive and excretory systems.     

Food spectrum analysis of the Asian toad,Duttaphrynus melanostictus (Schneider, 1799) (Anura: Bufonidae), from Timor Island,Wallacea

The Asian toad, Duttaphrynus melanostictus (Schneider, 1799), is widespread throughout tropical Asia and very abundant where it occurs. It was relatively recently introduced to Timor, the second largest island in the biogeographic region called Wallacea. Timor Island shows an exceptionally high level of endemism in a wide range of faunal groups and there are concerns that D. melanostictus may have a negative impact on this diversity, including vertebrates, through direct predation. To evaluate the impact the diet of D. melanostictus might have on the local fauna, gut contents of 83 preserved toad specimens from five habitat types in Timor-Leste, a country occupying the eastern half of Timor Island, were examined. We identified 5581 prey items, comprising the following animal groups: annelids; snails and slugs; spiders and harvestmen; woodlice; millipedes and centipedes; grasshoppers, crickets and earwigs; termites; thrips and true bugs; beetles; ants; hymenopterans other than ants; true flies; butterflies; unidentified insects; and insect larvae. Small eusocial insects (ants and termites) constituted the major part of the diet (61.6% and 23.4%, respectively). No vertebrate prey was recorded. Prey item composition did not differ between habitats. The wide prey spectrum well indicates that D. melanostictus is a generalist invertebrate feeder, as other studies, from regions where this species occurs naturally, have already shown. Although the Asian toad seems to not generally prey on vertebrates, vertebrate species that are morphologically similar to invertebrates in their overall appearance may be consumed. Hence, a negative effect on some taxa (e.g. blindsnakes) may be possible. We also present some limited data on intestinal parasites occurring in D. melanostictus.     

Microscopic morphology of the antennule and antenna of the marine isopod Cirolana harfordi

ABSTRACT

The use of scanning electron microscopy on the cuticle outgrowths called setae (that contain sensilla) in crustaceans is useful for, understanding how crustacean species sense their environment and for taxonomic studies. So far, most of the setal morphology studies have been performed on decapod crustaceans such as lobsters and shrimps and there has been a comparative lack of such research on marine isopods, from which terrestrial isopods such as woodlice or slaters have evolved. In the current study, electron microscopy was used to study the antennal setae of the marine isopod Cirolana harfordi using magnification powers of up to 40, 000. C. harfordi displayed a number of setal types including setae that had a sub-terminal pore that contained a cupule-shaped structure and plumose setae which are pennate in structure and have two rows of setules along the setal shaft in a fashion analogous to a palm leaf. These plumose setae may be useful to the animal in detecting water currents. Differences in the structure and placement of setae on the antennae of C. harfordi as compared to two other marine isopods, Bathynomus pelor and Natatolana borealis (that have had a comprehensive study of antennae setal morphology performed on them in previous studies) indicate that scanning electron microscopy of isopod setae may be useful in taxonomic studies of isopods.     

Micro-terraforming by Antarctic springtails (Hexapoda: Entognatha)

It has long been an axiom of Antarctic terrestrial ecology that interactions between terrestrial invertebrates and their abiotic environment are unidirectional: they are affected by their extreme environment in numerous ways, but they themselves do not affect their environment. Field observations in tandem with laboratory investigations of the exuvial refugia of the springtail Gomphiocephalus hodgsoni Carpenter, reported here, challenge this long-held assumption. These previously undescribed structures consist of minute lithic particulate matter that has been bound together by the accumulation of moult exuviae. Macrophotography, microscopy and manipulation assays demonstrated that the exuviae act as a kind of ‘cement’. Detachment of exuviae by emulsification indicated that this is mediated by the accumulation of cuticular hydrocarbons (retained in shed exuviae) at the lithic–exuvial interface. In addition to re-enforcing preferred microhabitat features by extending the hygrically buffered refuge phenotype, these structures contribute to primary soil formation processes through the structural cohesion of particulate matter. These by-products of moulting behaviour represent the first tangible evidence of environmental modification by terrestrial invertebrates on the Antarctic continent.     

L.—Two new Bittacidæ (Mecoptera)

Summary

The host-parasite relationships of Leptomonas ctenocephali from Ctenocephalides canis and Leptomonas sp. from Orchopeas h. howardi and Palaeopsylla m. minor are described. The latter two species of fleas are new host records for kinetoplastid flagellates. Attachment to pylorus and hindgut is by modification of the flagellum; hemidesmosomes are formed on the inner leaflet of the flagellar membrane and flagella-flagella desmosomes anchor adjacent flagella; a palisade of several layers of promastigote forms line the hindgut. Many individual flagellar membranes were found to extend around 3·0 μm and up to a maximum of 3·9 μm along the cuticular surface to which they were attached. In the rectum a specific association between the flagellates and the rectal ampullae is described; flagellates are attached to this surface covering completely each of the ampullae in heavy infections; again several layers of parasites coat the rectal ampullae. Attachment to the rectal ampullae is by the same mechanism as in the hindgut. Few parasites are attached to the rectal wall itself but rosettes of parasites attached by their flagella are observed in the lumen. The structure of the rectal ampullae are briefly described and the host-parasite relationships are discussed in the context of other described systems.     

Feeding habits of the endemic tropical parthenogenetic lizard Cnemidophorus nativo (Teiidae) in a restinga area of northeastern Brazil

The population of Cnemidophorus nativo in the restinga of Guaratiba, Bahia State, Brazil, is carnivorous with a diet consisting predominantly of insect larvae and termites, which is similar to that of other cnemidophorines. The absence of seasonal variation in diet may be a consequence of the availability of termites throughout the year. The small size of the termites and the ease with which both juveniles and adults eat larvae independent of their length were probably the cause of the poor relationship between lizard body measurements and mean number and volume of prey consumed.     

Cubitermes subarquatus termitaries as shelters for soil fauna in African rainforests

Most soil fauna in tropical rainforests require a pre-existing shelter for at least part of their life cycles. Among termites and ants, the most frequently encountered taxa, the availability of appropriate nesting sites is a major factor controlling the multiplication of colonies. Work carried out in five forests in southern Cameroon indicates that termitaries of Cubitermes subarquatus, whether active or abandoned, provide shelter for large numbers of invasive invertebrates, particularly ants and other termite species, and may be a determining factor in the patchy distribution of many taxa. Dissections of 90 termitaries (65 active, 25 abandoned) produced a great diversity of invasive fauna, including 354 ant colonies representing 75 species in 31 genera. Ants occurred in all abandoned termitaries but 6·1% of active termitaries had no ants present. Nevertheless, in total active termitaries sheltered more ant colonies (273) than did abandoned ones (81). Every termitary examined also sheltered founding pairs or incipient colonies of alien termites, but active C. subarquatus termitaries yielded fewer mature colonies of alien termites (56·9%) than did abandoned ones (84%).     

The termites of the Mayombe Forest Reserve,Congo (Brazzaville): transect sampling reveals an extremely high diversity of ground-nesting soil feeders

Sampling using a replicated standard transect method in an extensive undisturbed primary hill rain forest in Congo (Brazzaville) revealed a very high species richness of termites, especially soil-feeding soldierless termites (Apicotermitinae). The assemblage, as estimated by the transects, resembled that previously characterized in comparable forest in southern Cameroon, but with some species turnover reflecting the gamma diversity of the Guinean-Congolese block as a whole. Species richness was three or four times that shown by a previous study addressed to mound populations alone, emphasizing the importance of sampling soil-feeding termites neither building nor living in mounds.     

Histology of the alimentary canal of the mature larva of Prodenia litura Fabr. (Lepidoptera)

Summary

The histology of the alimentary canal of the mature larva of Prodenia litura Fabr. is described in detail. The status of the oesophageal and stomodaeal valves, structure and morphological relationship of the mesenteric cells and the structure and formation of the peritrophic membrane are discussed. The oesophageal epithelium is deeply compressed by the intruding muscules and the chitinous intima bears prominent spines thus forming a valve. The structure and function of this valve is quite different from that of the stomodaeal valve. The interstitial cells give rise to two different forms of mesenteric cells, viz. the columnar and goblet cells. There are clusters of unspecified cells at the anterior end of the mesenteron. The role of these cells appears to be secreting chitin which helps in forming the peritrophic membrane.     

Morphology and chaetotaxy of the immature stages of the scorpionfly Panorpa liui Hua (Mecoptera: Panorpidae) with notes on its biology

The immature stages of the scorpionfly Panorpa liui Hua were obtained through rearing. The egg, larva and pupa were observed using light and scanning electron microscopy with special reference to the chaetotaxy of the first instar larva and pupa. The larva is of the eruciform type, with three pairs of thoracic legs and eight pairs of abdominal prolegs. The head of the larva bears a pair of compound eyes, each of which consists of 26 ommatidia. A fleshy tibial lobe is borne distally on the mesal side of the tibia of the thoracic legs. The telson bears a protrusile sucker of four anal forks. The pupa is exarate and decticous with sexual dimorphism in chaetotaxy and caudal segments. This species completes two generations per year, overwintering as the prepupal stage in the soil. The durations of egg, larva and pupa are 3–4, 13–19 and 8–10 days, respectively.     

Ultrastructural study of the proboscis of Malacobdella grossa (Nemertea: Hoplonemertea)

The proboscis of the symbiotic nemertean Malacobdella grossa was examined with transmission electron microscopy to reveal more features of bdellonemerteans for phylogenetic analysis. General morphology of the proboscis of Malacobdella corresponds to that of a typical hoplonemertean: the middle chamber is present; the nervous system of the proboscis is embedded in the connective tissue between the inner and outer longitudinal muscle layers; the radially arranged nerve trunks are clearly seen over a considerable portion of their extent. Unique features (i.e. autapomorphies) of Malacobdella’s proboscis include: interwoven longitudinal muscle fibres; nerve plexus in the anterior part of the proboscis; absence of mucus glands; presence of subepithelial glands; reduced musculature in the middle chamber; and absence of glandular epithelium in the posterior chamber.     

Arctic species of the cheilostome bryozoan Microporella,with a redescription of the type species

This investigation focuses on the diversity and taxonomy of species of Microporella found north of the Arctic Circle. Firstly, however, a neotype is chosen for the Mediterranean type species M. ciliata (Pallas) in order to stabilize the taxonomy of this “pseudocosmopolitan” species, which has been recorded in the past from the Arctic. Study of type and other material using scanning electron microscopy shows that only two Arctic species of Microporella can be recognized, M. arctica Norman and M. klugei sp. nov. The first of these is characterized by a large ascopore divided by thin radial septa and situated close to the proximal rim of the orifice. Microporella klugei sp. nov. differs in having a smaller, undivided ascopore situated in a more proximal position on the frontal shield. Both Arctic species are notable among Microporella species for having a high proportion of autozooids without associated avicularia.     

Sperm ultrastructure in two species of Gyraulus (Gastropoda: Pulmonata: Planorbidae)

Sperm morphology offers a rich source of potentially informative characters for gastropod taxonomy and in this study it was used to provide additional information for Gyraulus (Armiger) crista (Linnaeus, 1758), whose taxonomic position within the Planorbidae Rafinesque, 1815 remains uncertain. Sperm morphology in G. (A.) crista and G. (Gyraulus) albus (Müller, 1774), the type species of the genus, was examined using light microscopy, scanning electron microscopy and transmission electron microscopy. The ultrastructure of spermatozoa in the two species was found to conform to the general pattern characteristic of the Hygrophila Férussac, 1822: the spermatozoa had an anterior head containing an acrosomal complex (apical vesicle and acrosomal pedestal) and cone-shaped nucleus, followed by a very long midpiece with glycogen spirals, and then by a glycogen piece and tail. Although the spermatozoa of the two species shared some common features (one nuclear keel and four glycogen spirals), they differed significantly in length, morphology of the annulus and structure of the spiral surface ridges. There were also some differences in the size and structure of the acrosomal pedestal and the shape of the nucleus. The spermatozoa of the two Gyraulus species are compared with those of other Hygrophila and the possible importance of sperm morphology for the taxonomic status of G. (A.) crista is discussed.     

Pseudonemesia tabiskey,a new species of Pseudonemesia Caporiacco 1955 and new ultramorphological data for the Microstigmatinae (Araneae: Microstigmatidae)

Pseudonemesia tabiskey sp. nov. is described from an Andean Forest in Trujillo, Venezuela. The new species is the third for the genus and differs from the other two species by the presence of one short and apically rounded modified seta on the retrolateral distal portion of the male tibia I and clavate setae on the dorsal and lateral sides of abdomen in both sexes. A new diagnosis is given to Pseudonemesia and new morphological data based on scanning electron microscopy for the Microstigmatinae are presented. The presence of posterior median spinnerets in Pseudonemesia is discussed.     

Two new termite-eating Diores species (Araneae,Zodariidae) and some observations on unique prey immobilization

Two new taxa, Diores termitophagus n. sp. and D. magicus n. sp. are described. The species have been observed to prey on termites (Hodotermes mossambicus Hagen) and are assumed to be compulsory termite-eaters. Similar prey-specialization has recently been observed in other Diores species. Termites were observed to be immobilized and die after superficial contact with the spiders; only thereafter were they bitten and eaten.     

Diet and sexual dimorphism of the desert iguana, Dipsosaurus dorsalis, from Sonora, Mexico

We examined the diet and sexual dimorphism of the desert iguana, Dipsosaurus dorsalis, from Sonora, Mexico. The diet consisted primarily of vegetation, with insect material contributing little to the overall volume of the diet. Plant matter was restricted to leaves and seeds. Animal prey consisted mostly of ants, termites, and beetles. Males and females did not differ significantly in snout–vent length, head length, or head width. These results confirm that in general D. dorsalis is herbivorous and not sexually dimorphic through much of its range. Examinamos la dieta y dimorfismo sexual de la Iguana del Desierto, Dipsosaurus dorsalis, en Sonora, México. La dieta consistió principalmente de vegetales, con insectos contribuyendo poco al volumen total de ésta. La materia vegetal estuvo restringida a hojas y semillas. Las presas animales consistieron principalmente de hormigas, termitas, y escarabajos. Machos y hembras no difirieron significativamente en longitud hocico cloaca, longitud de la cabeza, o ancho de la cabeza. Estos resultados confirman que en general D. dorsalis es una especie herbívora que no presenta dimorfismo sexual en la mayor parte de su intervalo de distribución.     

Prey choice and raiding behaviour of the Ponerine ant Pachycondyla analis (Hymenoptera: Formicidae)

Termite raiding behaviour of the African poneromorph ant Pachycondyla analis was studied at Mpala, Kenya. In all, 330 raids were observed with the raiding activity showing peaks in the morning and evening. Time spent at the termite source was positively correlated with the numbers of termites taken. The sizes of foraging parties, number of termites taken, distance travelled and time spent at termite sources also showed a positive correlation. Pachycondyla analis preyed significantly more on Microtermes spp. than they did on Odontotermes spp. but no significant differences were found in terms of predator efficiency even though many ants were injured in raids on Odontotermes spp. compared with those on Microtermes spp. Our results indicate that P. analis seems to forage optimally, balancing the costs of energy with prey reward and prey choices were not only influenced by prey abundance, but also by the costs of foraging, as influenced by prey defences, size and foraging behaviour.     

Food habits of the western whiptail lizard ( Cnemidophorus tigris ) in southeastern New Mexico

This study presents the first food habit assessment for the western whiptail lizard ( Cnemidophorus tigris ) in the shinnery oak – mesquite habitat ( Quercus havardii – Prosopis glandulosa ) of southeastern New Mexico. Short-horned grasshoppers, termites, antlions, beetles, and spiders formed the major portion of the diet during the four-year study. Discriminant analyses were used to evaluate annual, seasonal (monthly), and sexual variation. Incidental food categories were responsible for most of the annual and seasonal variation. Dominant foods varied little between months and years. Sexual variation was more evident; it may act to reduce intraspecific competition for food resources and may be associated with secondary sexual size dimorphism.         

Undescribed anatomical features of the gut of the house cricket,Acheta domesticus L. (Insecta,Orthoptera)

Summary

The following new anatomical features of the gut of Acheta domesticus are described and discussed:

• 1.A thin-walled dorsal evagination of the oesophagus, which may serve to circulate digestive fluid in the crop.

• 2.Lateral invaginations of the wall of the posterior oesophagus and anterior crop, separated from the circular muscle layer and allowing considerable enlargement of the foregut during feeding.

• 3.Strands of muscle and connective tissue linking the caeca and crop to the thoracic cuticle, innervated in part from the prothoracic ganglion, which may serve to register the extent of gut filling.

• 4.Evidence from the arrangement of the gut tracheae and nerves of rotation of parts of the gut from their original ancestral position, the gizzard and caeca being rotated through 90° and the crop through 180°. It is suggested that these rotations have been necessary to accommodate the gut components to changes in the shape and proportions of the body during the evolution of the cricket lineage.