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Phylogenetic Importance (phylogenetic + importance)
Selected AbstractsThe musculature of three species of gastrotrichs surveyed with confocal laser scanning microscopy (CLSM)ACTA ZOOLOGICA, Issue 3 2006Francesca Leasi Abstract The muscular system of gastrotrichs consists of circular, longitudinal and helicoidal bands that when analysed with confocal laser scanning microscopy, provide new insights into their functional organization and phylogenetic importance. We therefore undertook a comparative study of the muscle organization in three species of Gastrotricha from the orders Macrodasyida (Paradasys sp., Lepidodasyidae; Turbanella sp., Turbanellidae) and Chaetonotida (Polymerurus nodicaudus, Chaetonotidae). The general muscle organization of the marine interstitial macrodasyidans, Paradasys and Turbanella, not only confirms earlier observation on other species but also adds new details concerning the organization and number of helicoidal, longitudinal and other muscle bands (e.g. semicircular band). The freshwater, epibenthic,epiphytic chaetonotid, Polymerurus nodicaudus, has a similar muscular organization to other species of Chaetonotidae, especially species of Chaetonotus, Halichaetonotus and Lepidodermella. Perhaps unique to Polymerurus is the combined presence of an unbranched Rückenhautmuskel (also in Halichaetonotus and Lepidodermella) and a specialized dorsoventral caudal muscle, which flank the splanchnic component of the longitudinal muscles (only in Chaetonotus and Lepidodermella). This combination, together with the presence of splanchnic dorsoventral muscles, known only in Xenotrichulidae, implies a unique phylogenetic position for Polymerurus, and indicates a potential basal position of this taxon among the Chaetonotidae studied so far (i.e. Aspidiophorus, Chaetonotus, Halichaetonotus and Lepidodermella). [source] The first record of Late Jurassic crossognathiform fishes from Europe and their phylogenetic importance for teleostean phylogenyFOSSIL RECORD-MITTEILUNGEN AUS DEM MUSEUM FUER NATURKUNDE, Issue 2 2010Gloria Arratia Abstract The Late Jurassic Bavarichthys incognitus, n. gen. n. sp. from Ettling, Bavaria, is described. The new species represents the oldest record of a crossognathiform in Europe and together with Chongichthys from the Oxfordian of South America stands at the basal levels of a clade including crossognathids and pachyrhizodontoids. In addition, the new fish represents the first record of a crossognathiform in the Solnhofen Limestones. The new genus is characterized by numerous features such as the presence of infraorbitals 1,3 independent and 4 + 5 fused; two supramaxillary bones present; supramaxilla 2 considerably shorter than supramaxilla 1 and lacking an antero-dorsal process; well-developed series of epineural, epicentral and epipleural intermuscular bones; parhypural and hypurals 1 and 2 partially fused to each other; a series of epaxial basal fulcra; and a few, elongate fringing fulcra associated with the dorsal leading margin of caudal fin. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Pigmented eyes, photoreceptor-like sense organs and central nervous system in the polychaete Scoloplos armiger (Orbiniidae, Annelida) and their phylogenetic importanceJOURNAL OF MORPHOLOGY, Issue 11 2009Verena Wilkens Abstract The phylogenetic position of Orbiniidae within Annelida is unresolved. Conflicting hypotheses place them either in a basal taxon Scolecida, close to Spionida, or in a basal position in Aciculata. Because Aciculata have a specific type of eye, the photoreceptive organs in the orbiniid Scoloplos armiger were investigated to test these phylogenetic hypotheses. Two different types of prostomial photoreceptor-like sense organs were found in juveniles and one additional in subadults. In juveniles there are four ciliary photoreceptor-like phaosomes with unbranched cilia and two pigmented eyes. The paired pigmented eyes lie beside the brain above the circumoesophageal connectives. Each consists of one pigmented cell, one unpigmented supportive cell and three everse rhabdomeric sensory cells with vestigial cilia. During development the number of phaosomes increases considerably and numerous unpigmented sense organs appear consisting of one rhabdomeric photoreceptor cell and one supportive cell. The development and morphology of the pigmented eyes of S. armiger suggest that they represent miniaturized eyes of the phyllodocidan type of adult eye rather than persisting larval eyes resulting in small inverse eyes typical of Scolecida. Moreover, the structure of the brain indicates a loss of the palps. Hence, a closer relationship of Orbiniidae to Phyllodocida is indicated. Due to a still extensive lack of ultrastructural data among polychaetes this conclusion cannot be corroborated by considering the structure of the unpigmented ciliary and rhabdomeric photoreceptor-like sense organs. J. Morphol., 2009. © 2009 Wiley-Liss, Inc. [source] Marked sperm dimorphism in the ground beetle Scarites terricola: a novel type of insect sperm polymorphismPHYSIOLOGICAL ENTOMOLOGY, Issue 4 2009KÔJI SASAKAWA Abstract. Sperm polymorphism describes the phenomenon of male ejaculates containing two or more distinct types of sperm. In insects, four types of sperm polymorphism are recognized in species from the orders Diptera, Hemiptera, Hymenoptera, Lepidoptera and Coleoptera. The present study describes dimorphic sperm of the ground beetle Scarites terricola (Coleoptera: Carabidae) as a novel type of sperm polymorphism in insects. Sperm from the spermatophore and male seminal vesicles are examined at the light-microscopic level, and both display marked dimorphism. One type has sperm formed into bundles, in which the head of numerous spermatozoa are ,glued' together, with tails free-moving. The other type are free as single spermatozoa and have a disproportionately large-sized head and an elongated tail. Both types are motile in Ringer's solution. The adaptive and phylogenetic importance of these findings is discussed. [source] Virtual study of the endocranial morphology of the matrix-filled cranium from Eliye Springs, KenyaTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 2 2004Günter Bräuer Abstract This paper provides the first endocranial description of the matrix-filled archaic Homo sapiens cranium from Eliye Springs, Kenya. Using CT-based 3D reconstruction, the virtually cleaned endocranial surface allowed for the assessment of more than 30 metrical and nonmetrical features, most of which are considered of phylogenetic importance. The VOXEL-MAN program used was most valuable in describing and analyzing the morphological conditions. Since many of the features have not been widely or virtually studied, a small sample of late Pleistocene/early Holocene skulls from East Africa was similarly analyzed for insight into recent variation. The comparisons between Eliye Springs and the modern African specimens showed that the endocranial morphology of this probably later Middle Pleistocene hominid falls into, or close to, the modern ranges of variation for most features. This study also addresses the problems of variation and phylogenetic significance of many of the features, and highlights the need for basic studies on the variability and relevance of such endocranial traits in human evolution. Anat Rec Part A 276A:113,133, 2004. © 2004 Wiley-Liss, Inc. [source] | ||||||||||