Is the enigma a variation? Sagina boydii F. B. White (Caryophyllaceae), Boyd's pearlwort

Sagina boydii F. B. White (Caryophyllaceae), Boyd's pearlwort, is an enigmatic taxon of unknown geographical origin which is only known in cultivation and is of uncertain taxonomic status. Morphological, cytological and geographical evidence suggests that it is most similar to S. procumbens L. and S. saginoides (L.) H. Karst., but it differs in its compact growth form. Genetically, AFLP analysis shows that it can be included as part of the variation in S. procumbens . In cultivation, it will grow true from seed. Other compact growth forms occur in S. procumbens but do not grow true from seed. As S. boydii is part of the variation in S. procumbens , is of uncertain geographical origin, is known only in cultivation, and grows true from seed, it is best treated as a new cultivar, Sagina procumbens 'Boydii'. A neotype and standard specimen is designated.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 147 , 203–211.     

Allopolyploid origin of Cardamine silana (Brassicaceae) from Calabria (southern Italy): karyological, morphological and molecular evidence

Endemic Cardamine silana from Calabria (southern Italy) previously reported to be related to C. raphanifolia was found to be hexaploid. Morphological characters and AFLP data were analysed to evaluate the degree of differentiation of C. silana from closely related taxa and to find parental taxa of this polyploid. Cardamine apennina from the C. pratensis group was examined as one putative parent, as indicated in previous studies of nuclear ITS sequences, along with other related taxa based on both cpDNA and ITS sequences. Both multivariate morphometric analyses of quantitative characters and evaluation of qualitative morphological characters showed: (1) closest position of C. silana to two diploids: C. acris from the Balkan Peninsula and C. apennina from Central Italy; (2) good extent of morphological separation of C. silana from related taxa; and (3) within C. acris subspecies, C. acris ssp. vardousiae from Central Greece as closest to C. silana . Neighbour-joining tree and PCoA ordinations of AFLP data, as well as patterns of AFLP bands sharing, corroborated results of multivariate morphometrics. This evidence supports an allopolyploid origin of C. silana , with C. apennina and C. acris as parental taxa. Its origin may be dated to Pleistocene glacial events, because of the presumably wider geographical distributions of its parental taxa during more humid periods at that time.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 148 , 101–116.     

Brood chambers constructed from spines in fossil and Recent cheilostome bryozoans

Most cheilostome bryozoans brood their larvae in skeletal structures called ovicells which, in evolutionary terms, were derived from spines. Ovicells in the great majority of fossil and Recent cheilostomes, however, have lost all or most traces of their spinose origin. Here we review the occurrence of spinose (including costate) brood chambers in cheilostomes, investigating in detail 32 species belonging to ten genera among five families (Calloporidae, Monoporellidae, Macroporidae, Cribrilinidae and Tendridae). Spinose ovicells are moderately common in the Upper Cretaceous, where they are recorded in 28 species, and also occur in one Palaeocene, seven Eocene‐Miocene and 11 Recent species. The most primitive cheilostome ovicells occur in mid‐Cretaceous calloporids in which a group of mural spines belonging to the distal zooid were apparently bent towards the maternal zooid to form a cage‐like structure for reception of the embryo. The bases of these spines were initially aligned in a distally concave row that later became straight, distally convex and finally horseshoe‐shaped, affording progressively better protection for the developing embryo. We suggest that primitive monoporellids inherited from calloporid ancestors a distally concave arrangement of ovicell spine bases, while cribrilinids inherited a horseshoe‐shaped arrangement. Important trends that can be recognized in early ovicell evolution include: (1) loss of basal spine articulation; (2) spine flattening; (3) closure of the gaps between spines; (4) reduction in spine number (through loss or fusion), and (5) development of a concave ovicell floor. The conventional ‘unipartite’ ovicells found in the majority of cheilostomes may have originated either by spine fusion, as seems likely in some cribrilinids, or through a progressive loss of spines via an intermediate stage, seen in some calloporids and in two monoporellids, where the ovicell comprises a large pair of flattened spines. The spinose ovicells of some monoporellids and macroporids subsequently evolved investments of hypostegal coelom that allowed secretion of a surface layer of cryptocystal calcification. Acanthostegous brood chambers characteristic of Tendridae apparently provide an example of independent evolution of spinose brooding structures. © 2005 The Natural History Museum, London, Zoological Journal of the Linnean Society, 2005, 144 , 317?361.     

A heterochronic interpretation of the origin of digging adaptations in the northern water vole, Arvicola terrestris (Rodentia: Arvicolidae)

The Palaearctic genus Arvicola includes two species: the south‐western water vole A. sapidus, and the northern water vole A. terrestris. The latter has semiaquatic and/or subterranean populations, while populations of A. sapidus are always semiaquatic. According to the current phylogenetic and palaeontological data, adaptation to semiaquatic life is plesiomorphic for the genus Arvicola. We studied the ontogenetic allometry of skull and long bones of the semiaquatic A. sapidus, a semiaquatic population of A. terrestris (A. t. italicus), and two fossorial populations of A. terrestris (A. t. scherman and A. t. monticola). Animals from fossorial populations were smaller than were those from semiaquatic populations. We found that most of the ontogenetic allometric exponents of characters linked to digging in the skull and in the long bones were significantly higher in A. t. monticola, a fossorial clade, than they were in the semiaquatic populations. On the other hand, there may have been an evolutionary lag between invasion of the hypogeic habitat and the acquisition of fossorial adaptations in A. t. scherman. We showed statistically that the morphological differences linked to the invasion of a hypogeic habitat are already present in juvenile animals and, according to these results, suggest that these morphological differences are the direct expression of genetic changes rather than the outcome of epigenetic factors of mechanical origin. Moreover, we tried to ascertain whether the apomorphic shape of the skull and long bones in the fossorial populations of A. terrestris (compared with the primitive condition that would have been retained by the semiaquatic A. sapidus) are the outcome of a heterochronic process. Optimization by squared change parsimony supported the hypothesis of an apomorphic reduction of body size linked to the invasion of the subterranean habitat. The comparison of the ontogenetic trajectories of both skull shape and long bone shape suggested that a heterochronic process was involved in this morphological transformation. By using the ‘clock model’ method, this mechanism was identified as ‘accelerated dwarfism’ affecting both the skull and long bones. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 87 , 381–391.     

Variations in the microsporogenesis of monosulcate palm pollen

Pollen morphology has been extensively studied in the Arecaceae, and pollen aperture organization is usually distal monosulcate, as in many monocot families. Much is known about the influence of microsporogenesis on aperture configuration, but the key processes during microsporogenesis responsible for aperture type, number and arrangement are still poorly understood. In order to clarify the developmental sequence underlying aperture type and organization in palm monosulcate pollen, a study of the characteristics of male postmeiotic development was carried out in representative species of four genera of subfamily Coryphoideae, and four genera of subfamily Arecoideae. We found evidence for the occurrence of successive cytokinesis in addition to simultaneous cytokinesis in three Coryphoideae species. Tetrad shape was highly diverse within all species. Our results reveal an unexpected diversity in microsporogenesis from which it may be possible to gain further insight into pollen evolution within the family.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 151 , 93–102.     

The shape of the mandibular corpus in large fissiped carnivores: allometry,function and phylogeny

Mandibular corpus shape variability was investigated in seven families of both extant and extinct mammalian carnivores using two‐dimensional landmarks and geometric morphometric methods. The landmark configuration represents the position of the fourth premolar relative to the canine and the lower carnassial, plus related features of the corpus profile. Between families, the corpus manifests differences in shape and allometry. Additionally, families differ in the relationship between the angle α (a carnassial trait proxy for hypo‐hypercarnivory) and mandibular corpus shape. When phylogenetic relatedness is taken into account using five different phylogenies as covariates, interspecific scaling is still present but the relationship between α and corpus shape is no longer significant. This suggests that the allometric relationship reflects the physical constraints of mastication, resulting in relatively increased corpus depth with higher loads. In contrast, the angle α is related to corpus curvature and this relationship is phylogenetically constrained by the reduction of the molar battery in large feliforms early during the carnivore radiation. In summary, large fissiped carnivores show extensive functional convergence in mandibular corpus shape although the evolutionary routes leading to such functional convergence are different. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 154 , 832–845.     

A phylogenetic analysis and taxonomic revision of ricefishes,Oryzias and relatives (Beloniformes,Adrianichthyidae)

Ricefishes, known best by the model organism, the medaka, Oryzias latipes Temminck & Schlegel, 1846, comprise the family Adrianichthyidae, which ranges broadly throughout fresh and brackish waters of Central, South and Southeast Asia and the Indo‐Malay‐Philippines Archipelago as far east as Timor. Twenty‐eight Recent species are recognized here in two monophyletic genera, Adrianichthys and Oryzias. Xenopoecilus and Horaichthys are placed in synonymy of Oryzias for the first time. Adrianichthys comprises four species from Lake Poso, Sulawesi, Indonesia. Oryzias comprises 24 species that live throughout the range of the family. A fossil genus and species, ?Lithopoecilus brouweri from the Miocene of central Sulawesi, is included tentatively in the Adrianichthyidae. Evidence for the sister group relationship of adrianichthyids and exocoetoids is reviewed briefly and that relationship corroborated. Monophyly of adrianichthyids is likewise strongly supported here. Species groups within Oryzias are diagnosed as monophyletic largely based on osteology, colour pattern and meristic variation. They correspond only in part to species groups previously recognized based on chromosome constitution. Miniature species do not comprise a monophyletic group; disjunct absolute size in close relatives has evolved repeatedly. Oryzias latipes is a member of a species complex that includes O. luzonensis, O. curvinotus and the miniatures O. sinensis and O. mekongensis. A new species, Oryzias bonneorum sp. nov. , is described from Lake Lindu, Sulawesi, Indonesia. Lectotypes are designated for Haplochilus celebensis Weber, 1894 and Haplochilus timorensis Weber & de Beaufort, 1922. No claim to original US Government works. Journal compilation © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 154 , 494–610.     

Comparative floral structure and systematics in Chrysobalanaceae s.l. (Chrysobalanaceae, Dichapetalaceae, Euphroniaceae, Trigoniaceae; Malpighiales)

Chrysobalanaceae s.l. , one of the few suprafamilial subclades of Malpighiales that is supported by molecular phylogenetic analyses, and containing Chrysobalanaceae, Dichapetalaceae, Euphroniaceae, and Trigoniaceae, was comparatively studied with regard to floral structure. The subclade is well supported by floral structure. Potential synapomorphies for Chrysobalanaceae s.l. are the following shared features: floral cup; flowers obliquely monosymmetric; sepals congenitally united at base; sepals of unequal size (outer two shorter); fertile stamens concentrated on the anterior side of the flower and sometimes united into a strap; staminodes absent in the posteriormost antepetalous position; anthers extremely introrse, with thecae almost in one plane; endothecium continuous over the dorsal side of the connective; dorsal anther pit; gynoecium completely syncarpous up to the stigma; carpel flanks slightly bulged out transversely and thus carpels demarcated from each other by a longitudinal furrow; flowers with dense unicellular, non-lignified hairs, especially on the gynoecium; light-coloured, dense indumentum on young shoots and inflorescences. Potential synapomorphies for Chrysobalanaceae + Euphroniaceae include: spur in floral cup; clawed petals; lignified hairs on petals; nectary without lobes or scales and mostly annular. Potential synapomorphies for Dichapetalaceae + Trigoniaceae include: special mucilage cells in sepals in mesophyll (in addition to epidermis); anthers almost basifixed; gynoecium synascidiate up to lower style; nectary with lobes or scales and semi-annular.  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 157 , 249–309.