Larval development in the Homoscleromorpha (Porifera, Demospongiae)

Abstract. Embryonic development from coeloblastula to fully developed larva was investigated in 8 Mediterranean homoscleromorph species: Oscarella lobularis, O. tuberculata, O. microlobata, O. imperialis, Plakina trilopha, P. jani, Corticium candelabrum , and Pseudocorticium jarrei. Morphogenesis of the larva is similar in all these species; however, cell proliferation is more active in species of Oscarella than in Plakina and C. candelabrum. The result of cell division is a wrinkled, flagellated larva, called a cinctoblastula. It is composed of a columnar epithelium of polarized, monoflagellated cells among which are scattered a few non-flagellated ovoid cells. The central cavity always contains symbiotic bacteria. Maternal cells are also present in O. lobularis, O. imperialis , and P. jarrei. In the fully developed larva, cell shape and dimensions are constant for each species. The cells of the anterior pole have large vacuoles with heterogeneous material; those of the postero-lateral zone have an intranuclear paracrystalline inclusion; and the flagellated cells of the posterior pole have large osmiophilic inclusions. Intercellular junctions join the apical parts of the cells, beneath which are other specialized cell junctions. A basement membrane underlying the flagellated cells lines the larval cavity. This is the first observation of a basement membrane in a poriferan larva. The basal apparatus of flagellated cells is characterized by an accessory centriole located exactly beneath the basal body. The single basal rootlet is cross striated. The presence of a basement membrane and a true epithelium in the larva of Homoscleromorpha—unique among poriferan clades and shared with Eumetazoa—suggests that Demospongiae could be paraphyletic.     

Morphogenesis accompanying larval metamorphosis in Plakina trilopha (Porifera, Homoscleromorpha)

Morphological investigations of morphogenesis accompanying the metamorphosis of the cinctoblastula larva of poriferan Plakina trilopha (Homoscleromorpha) have been made. The larva possesses a distinct columnar epithelium which subdivides into three cellular areas: antero-lateral, postero-lateral, and posterior one. Characteristic morphological features of the cells in each area can be used as natural markers when tracing the fate of larval cells during metamorphosis. The ciliated epithelium of the larva is transformed directly into choanoderm and pinacoderm, without losing its organization. This transformation is a peculiar feature of the metamorphosis in Homoscleromorpha. Metamorphosis in P. trilopha is based on epithelial morphogenesis and includes the mechanisms of flattening of the exopinacoderm, evagination and invagination of larval epithelium in the course of the development of the rhagon aquiferous system. The flattening of larval cells during exopinacoderm formation in metamorphosing P. trilopha is a common change of cell shape during epithelial morphogenesis of this species. The separation of proximal fragments of cells has been observed here. This phenomenon, that we have called “cytoplasmic shedding”, appears to play an important role in the change of epithelial cell shape in P. trilopha. Mechanism of epithelial–mesenchymal transition, i.e., ingression of epithelial ciliated cells into the cavity of the metamorphosing larva of P. trilopha participates in mesohylar cell origin.     

Association of the sponge Tethya orphei (Porifera, Demospongiae) with filamentous cyanobacteria

Abstract. Specimens of the sponge Tethya orphei , collected in February 2005 on the underside of coral stones on Arì Athol (Maldives), have been processed for histological and ultrastructural investigations. The cortical layer of the sponge was found to be permeated by filamentous cyanobacteria, the trichomes of which measured 45–63 μm on average and were composed of 10–14 cells. The fine organization of the filaments was consistent with their taxonomic identification as Oscillatoria spongeliae. These filaments filled the cortical region of the sponge and penetrated inward into the upper choanosomal region, where they sometimes overlapped the siliceous spicule bundles. A budding specimen of T. orphei showed that the filaments were also present in the single bud protruding from the sponge surface, demonstrating that asexual reproduction can vertically transmit these symbionts from sponge to sponge. The occurrence of filaments in all the specimens studied is consistent with the assumption that filamentous cyanobacteria are not mere intruders but mutualistic symbionts with members of T. orphei.     

Differences between two sympatric species of Tethya (Porifera, Demospongiae) concerning the growth and final form of their megasters

The megasters of T. aurantium and T. citrina consist, in their mature stage, of spherasters and spheroxyasters respectively. A study of the ratio between the ray length and the diameter of the centre (R/C), which determines the megaster shape, has been carried out on spicules of different size.
While the small megasters of these two species have a similar shape, successive stages show in T. aurantium an isometric growth and in T. citrina an allometric growth with rays growing faster than the centre. The two species differ also in the mean size, size frequency distribution and number of rays of the asters. Differences in the mean total diameter and shape were also detected among spicules coming from different regions of the sponge body. The taxonomic and evolutionary meaning of these phenomena are discussed.     

Morphological and genetic differences in ecologically distinct populations of Petrosia (Porifera, Demospongiae)

The taxonomic status of two sponge tnorphotypes living sympatrically in Mediterranean caves and usually ascribed to Petrosia ficiformis was elucidated on the basis of morphological, morphometric and genetic features. The two morphotypes, spherical and cylindrical, showed differences in the shape and size of spicules and in the morphology of the aquiferous system. Electrophoretic analyses demonstrated that the two morphotypes are reproductively independent and so they should be considered as distinct biological species. The spicular features allow attribution of the cylindrical morphotype to P.ficiformis and the spherical one to P. clavata. For these two species parasympatric speciation is proposed.     

Seed morphology and taxonomy of the North African species of Sideritis L. (Lamiaceae)

REJDALI, M., 1990. Seed morphology and taxonomy of the North African species of Sideritis L. (Lamiaceae). Seed morphology data are shown to support data from general morphology and palynology; they can be used for taxonomy at the sectional and specific levels. At times clear differences are apparent at the infraspecific level. Seed sculpturing was found to be of great value for separating taxa at all levels of the hierarchy.     

A reconsideration of the relationship between polyaxonid and monaxonid spicules in Demospongiae: new data from the genera Crambe and Discorhabdella (Porifera)

The relationships between different spicule lineages of Demospongiae are revised through the ontogenetic study of the main spicules of the genera Crambe and Discorhabdella. The presence of terminal orifices in the basal spines of the asterose acanthostyles of Discorhabdella, and the actines of the desmas of Crambe have been shown by examining young spicules under high magnification. Thus, the polyaxonid origin of both spicule types is hereby supported by the ontogenetic information, and their homology is also supported by their equivalent arrangement in the skeleton. The current differences in shape between both spicule types are considered the result of a divergent morphological evolution from an ancestral polyactinal corpuscle, by the atrophy/hypertrophy of a different number of actines. Arguments are also presented to support the homology of these two spicule types with the sphaeroclons of Vetulina, and other fossil genera. Moreover, the presence of axial canals inside the tubercles of the tuberose tylostyles of Discorhabdella and Crambe tuberosa indicates that the tubercles are actually atrophied actines as in the case of the hadromerid genus Terpios. According to the ontogeny, the tuberose morphology of these spicules may correspond to the retention of an ancestral characteristic in the Poecilosclerida and Hadromerida; in this case, a monophyletic origin, is suggested between both taxa. From the overall results here presented, the tetraxonid spicule, presently considered by most authors as the primitive morphotype, as well as some monaxons, could be considered as evolving from a polyaxial form.     

Taxonomic revision of the tribe Hymenodictyeae (Rubiaceae, Cinchonoideae)

The palaeotropical tribe Hymenodictyeae Razafim. & B. Bremer, belonging to the otherwise predominantly Neotropical subfamily Cinchonoideae  s.s. (coffee family or Rubiaceae), is revised here. The tribe as presently circumscribed contains two genera, Hymenodictyon Wall. and Paracorynanthe Capuron ex J.-F. Leroy, and is distinct from the other Cinchonoideae tribes with capsular fruits in having stipules bearing large, deciduous colleters on the margins, valvate corolla aestivation, and lenticellate capsular fruits that contain elongate, bilaterally flattened, and accrescent placentae. We recognize 22 Hymenodictyon species, including four new species ( H. antakaranensis sp. nov. , H. epiphyticum sp. nov. , H. madagascaricum sp. nov. , and H. tsingy sp. nov. ), and the two described species of Paracorynanthe . Hymenodictyon is distinguished from its sister genus, Paracorynanthe , by simple or compound spicate, racemose or thyrsoid inflorescences and corolla lobes without any appendages, rather than compound umbelliform inflorescences and corolla lobes prolonged by ciliate appendages. A full taxonomic treatment, keys, and distribution maps of all recognized Hymenodictyon and Paracorynanthe species are provided. Five lectotypes and one neotype are designated. Finally, six Hymenodictyon species are illustrated for the first time.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 152 , 331–386.     

Metamorphosis of cinctoblastula larvae (Homoscleromorpha, porifera)

The metamorphosis of the cinctoblastula of Homoscleromorpha is studied in five species belonging to three genera. The different steps of metamorphosis are similar in all species. The metamorphosis occurs by the invagination and involution of either the anterior epithelium or the posterior epithelium of the larva. During metamorphosis, morphogenetic polymorphism was observed, which has an individual character and does not depend on either external or species specific factors. In the rhagon, the development of the aquiferous system occurs only by epithelial morphogenesis and subsequent differentiation of cells. Mesohylar cells derive from flagellated cells after ingression. The formation of pinacoderm and choanoderm occurs by the differentiation of the larval flagellated epithelium. This is possibly due to the conservation of cell junctions in the external surface of the larval flagellated cells and of the basement membrane in their internal surface. The main difference in homoscleromorph metamorphosis compared with Demospongiae is the persistence of the flagellated epithelium throughout this process and even in the adult since exo- and endopinacoderm remain flagellated. The antero-posterior axis of the larva corresponds to the baso-apical axis of the adult in Homoscleromorpha.     

Epibiontic and endobiontic polychaetes of Geodia cydonium (Porifera,Demospongiae) from the Mediterranean Sea

Polychaete assemblages associated to the sponge Geodia cydonium were investigated at two sampling sites in the Mediterranean Sea: Porto Cesareo Basin (Apulia) and Marsala Lagoon (Sicily), both characterized by sheltered hydrodynamic conditions. Samples were seasonally performed during 1997, in order to compare the assemblages coming from the two localities studied, considering separately the internal and external tissues of the sponge, and with the aim of evaluating the influence of sponge size on polychaete colonization. The examined sponge is characterized by a peculiar stratification of its tissues: an external thick and hard layer, the cortex, and an internal softer one, the choanosome. Statistical analysis showed that this was the main factor controlling polychaete assemblage, with the internal tissue, less rich and diversified, appearing impoverished with respect to the external layer. A similarity in species composition was observed between sites, even though some differences were evidenced in the abundance of some species, mainly reflecting differences in local environmental conditions. Species richness and density increased with the increasing sponge size. Such a situation is particularly evident at Porto Cesareo, where sponges are covered by an algal layer which is particularly rich on the largest specimens, thus suggesting that most of the species of polychaetes were linked more to the neighbouring environment than to the sponge itself.     

Comparative morphology of the foliage leaf epidermis, with emphasis on papillae characters, in key taxa of woody bamboos of the Asian tropics (Poaceae: Bambusoideae)

The foliage leaf epidermis of 35 species representing 12 key genera of woody bamboos of the Asian tropics was investigated using light and scanning electron microscopy. The results indicated that papillae forms and distributional patterns around the stomatal apparatus of the abaxial foliage leaf epidermis were usually constant and were of great taxonomic significance at the specific and generic levels. However, papillae characters were not suitable for dividing subtribes within woody bamboos of the Asian tropics. On the basis of papillae characters, Schizostachyum s.s. and Cephalostachyum were confirmed, but their delimitations should be modified. The transfer of Leptocanna chinensis and Schizostachyum sanguineum into Cephalostachyum was supported, and Cephalostachyum virgatum and C .  pergracile were confirmed to be members of Schizostachyum s.s. The subtribe Racemobambosinae did not obtain support and Racemobambos appeared to be better placed in subtribe Bambusinae. Neomicrocalamus was supported as a close relative and better treated as a synonym of Racemobambos . Gigantochloa was closely related to Dendrocalamus .  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 156 , 411–423.     

An unexpectedly sophisticated, V-shaped spermatozoon in Demospongiae (Porifera): reproductive and evolutionary implications

The demosponge Crambe crambe shows a peculiar spermatogenesis, hard to be reconciled with the basal position of sponges in the animal phylogeny. Early spermatogenesis stages showed most of the simple features expected in sponges. However, spermiogenesis departed from the anticipated process. Spermatids lengthened remarkably, forming a deep cytoplasmic pit around the cilium insertion, with the proximal axoneme bending to produce a V-shaped spermatozoon surprisingly similar to that known in the phylum Phoronida. The cytology was unexpectedly complex, with a needle-like nucleus of helically condensed chromatin, a conical acrosome with a subacrosomal rod, and a mitochondrion connected to the basal body by striated rootlets. These findings establish that the spermatozoon of broad-casting demosponges occurs in two structural categories ('primitive' and 'modified' type). This dualistic condition must necessarily have pre-dated the evolutionary apparition of higher metazoans, if we are to keep regarding sponges as the most primitive animals. We hypothesize that internal fertilization in C. crambe – and incidentally other demosponges – may depart from the general model assumed for spermcasting sponges. The V-shape of this spermatozoon suggests a design to favour autonomous penetration through the dense mesohyl to reach the oocytes, rather than engulfment and transportation by carrier cells towards the oocyte.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 413–426.     

Symbiosis of Mycale (Mycale) vansoesti sp. nov. (Porifera, Demospongiae) with a coralline alga from North Sulawesi (Indonesia)

Abstract. The symbiotic association between the new sponge species Mycale vansoesti and the coralline alga Amphiroa sp. from the Bunaken Marine Park (North Sulawesi, Indonesia) is described. The alga completely pervades the sponge. The color of the sponge ectosome is white, both on the external surface and on the atrial wall, but where the alga is present the sponge takes on the light pink color of the alga. The sponge spicular complement is characterized by mycalostyles, anisochelae of two types, sigmas (often "C" shaped), and extremely abundant toxas organized in bundles forming toxadragma. In the association, the sponge shows very low silicate value, and consequently the alga represents the main skeleton of the sponge. On the other hand, the sponge affects the morphology of the alga, leading to a cylindrical shape, with thalli running parallel to the sponge surface. This association seems to be obligate for the sponge, as we found no sponges of this species living in isolation.     

A modern approach to demineralization of spicules in glass sponges (Porifera: Hexactinellida) for the purpose of extraction and examination of the protein matrix

Glass sponges of the class Hexactinellida are a group of the most ancient multicellular animals, whose fossil remnants from the early Proterozoic have been registered. In order to demineralize the skeletal structures of the glass sponge Hyalonema sieboldi, we have used for the first time a strategy of slow leaching of the silicon-bearing component, based on the usage of alkaline solutions of sodium hydroxide, sodium dodecyl sulfate, and an anionic biosurfactant of a rhamnolipid nature. The obtained data unequivocally corroborate the presence of a fibrillar protein matrix functioning as a basis for silicon biomineralization in the basal spicules of H. sieboldi. Also, it has been found for the first time that the protein matrix is constructed of a collagenous protein. The technical approach proposed here might appear important for the study of the structural organization of skeletons in other silicon-bearing animals and, in an applied aspect, to work out new biomaterials for implantology and biocomposites, in order to use the latter as bioactive additives.     

Hygrobates salamandrarum sp. nov. (Acari, Hydrachnidia, Hygrobatidae) from China: the First Record of a Freshwater Mite Parasitizing Newts (Amphibia, Urodela)

Females of a new water mite species of the genus Hygrobates (Acari, Hydrachnidia, Hygrobatidae) were found to parasitize Pachytriton labiatus (Unterstein, 1930) (Amphibia, Salamandridae), a newt species from S China. Obviously, their particularly modified mouthparts are an adaptation for penetrating the amphibian skin. These data provide the first record of an adult water mite parasitizing a vertebrate host.     

Revision and phylogenetic assessment of the rove beetle genus Pseudohesperus Hayashi,with broad reference to the subtribe Philonthina (Coleoptera: Staphylinidae: Staphylinini)

This paper studies the phylogeny of the rove beetle subtribe Philonthina, to test its hypothetical monophyly and to unravel the evolutionary relationships of the subtribe and its included genus‐level taxa, with emphasis on the genus Pseudohesperus and its close‐allied relatives. The phylogenetic analyses are based on 105 adult morphological characters and 66 terminal taxa, i.e., all six members of Pseudohesperus, 51 species to represent 29 other genera of the subtribe Philonthina, seven species to represent the other six subtribes of Staphylinini, one species of the tribes Arrowinini, and one of the Platyprosopini. According to the phylogenetic results obtained, the genus Erichsonius should move out from the hitherto‐defined subtribe Philonthina and thus the monophyly of this taxon is challenged. The phylogenetic tree suggests that the genera Hesperus and Belonuchus might not be monophyletic, but the monophyly of Pseudohesperus and the sister relationship between it and Bisnius are well supported. The species‐level phylogenetic relationships of the genus Pseudohesperus reveal a clear pattern of species diversification that can be correlated well with the species' zoogeographical patterns. The paper also revises the taxonomy of Pseudohesperus and describes five new species from China: Pseudohesperus luteus Li & Zhou sp. nov. , Pseudohesperus pedatiformis Li & Zhou sp. nov. , Pseudohesperus tripartitus Li & Zhou sp. nov. , Pseudohesperus sparsipunctatus Li & Zhou sp. nov. , and Bisnius lubricus Li & Zhou sp. nov. An identification key to the species of Pseudohesperus is provided and their geographical distributions are mapped. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 163 , 679–722.     

The pollen morphology of Vicia (Leguminosae)

The pollen morphology of 32 species of the genus Vicia was studied using scanning and transmission electron microscope (SEM and TEM). The interstitia of the pollen of the examined species were found to be either regular columellate, irregular columellate, or granular. The granular pattern was recognized to be apomorphy against the columellate patterns in the tribe Vicieae by comparison with the pollen in the tribes Vicieae, Cicereae, Galegeae, Hedysareae, and Trifolieae. The group of Vicia species having the apomorphy was congruent with that having a known apomorphy of the pistil character. This group with such synapomorphies may be monophyletic, though it is treated as polyphyletic in the present infrageneric system of Vicia.