The winding structure of the arteria radialis at its source

In the origin of the arteria radialis a loop-like formation was found. This unusual arrangement can be explained in the following way: from both the a. brachialis continuing into the a. ulnaris and the a. brachialis superficialis continuing into the a. radialis, aa. recurrens radialis branch off, which are connected by an anastomosis. The reduction of the a. brachialis superficialis results in the fact that the aa. recurrens radialis with their anastomosis have to take over the blood supply of the a. radialis and thus lead to the loop-like formation.     

The yeastKluyveromyces africanus nov. spec. and its phylogenetic significance

Summary A new budding yeast species isolated from soil is described. Its outstanding features are, firstly, the formation of asci containing up to sixteen long oval to reniform ascospores and, secondly, a fermentative as well as oxidative metabolism. The assimilation of nitrate is absent and no pseudomycelium is formed. The taxonomic position of the yeast is discussed and it is pointed out that, due to its exceptional ascospore number (1–16), it cannot be classified in any of the existing fermentative genera of theEndomycetaceae (in sensu Lodder et Kreger-van Rij). The reniform shape of its ascospores indicates, however, its close relationship with the multispored genusKluyveromyces, on the one hand, and the newly proposed one to four-spored genusDekkeromyces on the other. The species is provisionally classified as aKluyveromyces species,Kluyveromyces africanus nov. spec., until further information regarding its sexual characteristics becomes available. By virtue of its more or less intermediate ascospore number, it establishes the direct derivation of the genusDekkeromyces fromDipodascus uninucleatus via the multispored yeast genusKluyveromyces.     

Embryology of the Turbellaria and its phylogenetic significance

Developmental characters — including oocyte and yolk cell structure, patterns of cleavage, and modes of gastrulation — are presented and examined in relation to the phylogeny of the Turbellaria. Eggshell granules, which have been demonstrated to occur in the oocytes of entolecithal eggs and the yolk cells of ectolecithal eggs, are compared among species, and their potential value as a taxonomic character is discussed. The quartet 4d spiral cleavage of the entolecithal egg of polyclads is described as reminiscent of the primitive pattern of early development for the Turbellaria. This is compared to duet spiral cleavage of acoels, and possible phylogenetic schemes involving the two types of spiral cleavage are reviewed. The link between the precise spiral cleavage, which characterizes development of most archoophorans, and blastomere separation (Blastomeren-Anarchie), which occurs in several neoophoran orders, is established by the occurrence of quartet 4d spiral cleavage in one neoophoran order, and of both quartet spiral cleavage and Blastomeren-Anarchie in different species of a second neoophoran order. The epibolic gastrulation of polyclads is described as primitive for the Turbellaria because of its similarity to that of other members of the Spiralia. Although no identical process occurs in neoophoran development, the earlier event of formation of the hull membrane in some neoophorans, and the later event of formation of the definitive epidermis in all neoophorans studied are presented as processes of possible homology to the epibolic gastrulation of polyclads. The lack of correspondence between polyclads and neoophorans in the relationship of the definitive body axes to the egg axis is discussed, and an hypothesis is advanced to account for the differences. The phylogenetic relationships indicated by known developmental phenomena differ only slightly from the scheme presented by Karling in 1974.     

The origin of the coelom in Brachiopoda and its phylogenetic significance

The origin of the mesoderm and the subsequent formation of the coelom in the larvae of the brachiopod species Notosaria nigricans and Calloria inconspicua is documented in detail at the ultrastructural level. During gastrulation, the blastocoel is completely displaced by the invaginating archenteron. Initial mesoderm formation was observed in late wedge-shaped to early three-lobed stages in both species. Proliferation of mesodermal cells from the archenteral epithelium mainly occurs in the dorsolateral (C. inconspicua) and caudolateral (N. nigricans) parts of the archenteral wall. Thus, a compact mesodermal cell mass pushes its way towards the subepidermal basal lamina. During further development of the larva, the mesoderm is separated from the archenteral epithelium by an extracellular matrix secreted frontad from behind. As a result, a single coelomic anlage is formed. The initial mesoderm in both species is of archenteral/endodermal origin. Considering endodermal origin as the crucial character for enterocoely, coelom formation through proliferation of a compact, endodermally derived mesodermal cell mass in Brachiopoda is clearly identified as enterocoely. Endodermal origin of mesoderm and, therefore, of the coelomic epithelium is hypothesised as a synapomorphy of Brachiopoda and Deuterostomia. As a consequence: (1) Brachiopoda and Deuterostomia are considered sister groups, (2) Brachiopoda group within Radialia and (3) lophophorates (”Tentaculata”) remain as a paraphyletic grouping. Accepted: 26 November 1999     

The taxonomy of neolithic man and its phylogenetic relationship to later paleolithic man and modern man in China

In approaching the taxonomy of Neolithic Man and its phylogenetic relationship to Later Paleolithic Man and Modern Man in China, the statistical methods used here are Penrose's shape distance and PCA (Principal Component Analysis). The scattergram based on principal component scores, combines the dendrogram based on Penrose's shape distance, and takes the male taxonomy into main consideration, but takes the female taxonomy — as a reference only because the differentiations in physical characteristics among male populations generally are rather larger than those among the female populations. Thus according to this scattergram, Neolithic Man in China can be divided into two large groups: the Northern China group, and the Southern China group. The theory is that in Hengzhen there exist some blood mixtures between the Southern China Group and the Northern China Group (especially the third subgroup) of Neolithic Man. Later Paleolithic Man of China — Liujiang and Upper-Cave Man — can also clearly distinguished from the rest of Neolithic Man in China in the scattergram, and can be considered as two different local types of Later Paleolithic Man. So-called “Negro-Australoid” racial traits can themselves be doubtlessly traced back to Later Paleolithic Man of China — Liujiang and Upper-cave Man. These traits are the intrinsic characteristics of Neolithic Man in China and only then is there slight difference in the extent of the manifestation of these traits in the population.     

The sound-transmitting apparatus in primitive snakes and its phylogenetic significance

Summary The structure of the sound-transmitting apparatus in primitive snakes (Scolecophidia, Henophidia) is reviewed and compared with that of advanced snakes (Caenophidia) and of some fossorial lizards. Assuming a constant course of the chorda tympani, the ophidian stylohyal can be homologized with the intercalary cartilage of lizards while the cartilaginous distal portion of the ophidian stapes represents the internal process. The cladistic significance of the stapes-quadrate-articulation in the Henophidia and Caenophidia is discussed. The Booidea and the Caenophidia show a shift of the stapes-quadrate-articulation which is correlated with changes in the suspensorium as an adaptation to relatively larger prey. However, convergence cannot be ruled out. Dibamus is shown to be the only lizard known so far which approaches the ophidian middle ear structure. Convergence has to be assumed since there is no sign of a stylohyal in Dibamus and since the course of the ramus communicans externus n. facialis cum glossopharyngeo supports the hypothesis that snakes are to be derived from a pre-lacertilian stage of lepidosaurian evolution.

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Zusammenfassung Die Struktur des schalleitenden Apparates im Mittelohr primitiver Schlangen (Scolecophidia, Henophidia) wird beschrieben und mit höheren Schlangen (Caenophidia) sowie mit einigen grabenden Lacertiliern verglichen. Unter der Annahme eines konstanten Verlaufes der Chorda tympani lässt sich das Stylohyale der Schlangen mit dem Processus dorsalis homologisieren, während das knorpelige distale Ende des Stapes der Schlangen dem Processus internus entspricht. Die kladistischen Implikationen der Struktur des Mittelohres werden diskutiert. Die Booidea und die Caenophidia zeigen eine Verschiebung das Stapes-Quadratum-Gelenkes, welche möglicherweise mit Änderungen der Proportionen des Suspensoriums als Anpassung an relativ grössere Beute zusammenhängt. Konvergenz kann hierbei nicht ausgeschlossen werden. Dibamus ist die einzige bislang bekannte Echse welche im Bau des Mittelohres den Schlangen nahe kommt. Allerdings ist Konvergenz anzunehmen, da Dibamus keinerlei Hinweis auf das Vorhandensein eines Stylohyale liefert, und da der Verlauf des Ramus communicans externus n. facialis cum glossopharyngeo die Hypothese stützt, dass Schlangen nicht von rezenten Unterordnungen der Lacertilier abgeleitet werden können.

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Abbreviations (used in the figures) chr chorda tympani - ci carotis interior - crst cartilaginous distal extension of the stapedial shaft - dper ductus perilymphaticus - fc carotis facialis - par articulatory process of quadrate - pt pterygoid - q quadrate - rce ramus communicans externus - rci ramus communicans internus - st supratemporal - stp stapes - sty stylohyal - vcl vena capitis lateralis - lX n. glossopharyngeus - Vll_hy ramus hyomandibularis of facial nerve     

Ultrastructure of the spermatozoon of Lepidogalaxias salamandroides and its phylogenetic significance

The spermatozoon of Lepidogalaxias salamandroides possesses an acrosome (putative), one or two perforatoria (putative) but no nine-triplet centrioles. Two elongated mitochondria (12 μm long) are situated in parallel between the nucleus (20 μm long) and the axoneme (53 μm long). The above features are unique among other teleosts with internal fertilization. The presence of an “acrosome” in this primitive teleost supports the hypothesis that this structure has been secondarily lost in teleosts during evolution. The uncertainty of phylogenetic placement of this fish is reflected by its unique sperm ultrastructure.     

The spermatozoon of the Echiniscidae (Tardigrada,Heterotardigrada) and its phylogenetic significance

The spermatozoon ultrastructure of four species of moss-dwelling Heterotardigrada belonging to four genera of Echiniscidae, namely Pseudechiniscus juanitae, Echiniscus duboisi, Novechiniscus armadilloides and Antechiniscus parvisentus, was investigated. In all species, the testicular male gamete is similar in morphology and in length. The spermatozoon is made up of a long head, consisting of a cylindrical acrosome and an oval or rod-shaped nuclear region which contains a nucleus with osmiophilic and electron-dense chromatin, and a tapering tail, with a "9+2" axoneme. An elongated sack-like structure originates from the posterior part of the head, extending beyond the main axis of the cell and running parallel to the tail. It consists of two parallel tubular regions which sometimes form a strict double helix and contain two voluminous, "free" mitochondria with unmodified cristae. In addition, a voluminous vesicle is present laterally to the centriole or between the end of the nucleus and the beginning of the mitochondria, limited by two cytomembranes and filled with electron-lucent and granular material. The male gametes representative of these moss-dwelling Echiniscidae are very similar to the spermatozoa of the marine Echiniscoididae Echiniscoides sigismundi. This close similarity emphasises that habitat changes have had little influence on the organisation of the sperm cell representative of Echiniscoidea. Spermatozoon characters which could be useful for phylogenetic studies on Tardigrada are discussed.     

Among-site rate variation and its impact on phylogenetic analyses

Although several decades of study have revealed the ubiquity of variation of evolutionary rates among sites, reliable methods for studying rate variation were not developed until very recently. Early methods fit theoretical distributions to the numbers of changes at sites inferred by parsimony and substantially underestimate the rate variation. Recent analyses show that failure to account for rate variation can have drastic effects, leading to biased dating of speciation events, biased estimation of the transition:transversion rate ratio, and incorrect reconstruction of phylogenies.     

Fine structure of the pharyngeal bulb in Trilobodrilus and its phylogenetic significance within archiannelida.

Transmission electron microscopical studies of the pharyngeal bulb in the archiannelid Trilobodrilus sp. proved the presence of two opposing myofilament systems in the plate muscle cells forming this bulb. These muscles are obliquely striated. The significance as well as the origin of this specialized plate-muscle cells in the pharyngeal bulb of archiannelids is discussed in the light of their controversial phylogenetic and systematic position. In addition a hypothesis is suggested to explain the origin of the special arrangement of two opposing systems of myofilaments in one single muscle cell.     

The locomotion system of Mesozoic Coleoidea (Cephalopoda) and its phylogenetic significance

A morphological comparison of shell‐muscle contacts in coleoid cephalopods mainly from the Early Jurassic (Toarcian) Posidonia Shales of Holzmaden (Germany), the Middle Jurassic (Callovian) Oxford Clay of Christian Malford (UK), Late Jurassic (Kimmeridgian‐Tithonian) plattenkalks of Solnhofen (Germany), and the Late Cretaceous (Cenomanian) of Hâdjoula and Hâkel (Lebanon) provides new and meaningful insights into their locomotion systems. The study shows that both pro‐ostracum‐ and gladius‐bearing coleoids are typified by a marginal mantle attachment and by distinctly separated fins, which usually insert (indirectly via the shell sac and basal fin cartilages) to posterior shell parts. While absent in gladius‐bearing forms, mantle‐locking cartilages might have existed already in pro‐ostracum‐bearing belemnoids. Similar to ectocochleate ancestors, funnel‐ and cephalic retractors are generally attached to the internal (ventral) shell surface. A comparison of Mesozoic and Recent gladius‐bearing coleoids shows that the locomotion system (most significantly the dorsal mantle configuration, and the presence of nuchal‐ and funnel‐locking cartilages) is fundamentally different. This does not support the concept of ‘fossil teuthids’, but suggests, owing to similarities with Recent Vampyroteuthis, placement of Mesozoic gladius‐bearing coleoids within the Octobrachia (Octopoda + Vampyromorpha). Classification of Mesozoic gladius‐bearing coleoids as octobrachians implies that: (1) unambiguous teuthids are still unknown in the fossil record and (2) the similarity between Recent and some fossil gladiuses represents a matter of homoplasy.     

The rhabdom structure in the ommatidia of the Heteroptera (Insecta), and its phylogenetic significance

In its plesiomorphic state the insect ommatidium consists of eight retinula cells forming a fused rhabdom. It has long been observed that, in contrast to this pattern, Heteroptera have open rhabdoms. However, there has so far been no comprehensive and comparative study of heteropteran ommatidia. For this reason, we investigated the rhabdom structure in 36 species from all higher groups of Heteroptera, as well as from Coleorrhyncha and Auchenorrhyncha as outgroup representatives. In addition we surveyed the data of earlier authors, which brings the number of examined species to a total of more than 70. All examined Heteroptera do have open rhabdoms, with a system of six peripheral and two central rhabdomeres. Outgroup comparison shows that the open rhabdom is an autapomorphy of the Heteroptera. As for the rhabdom structure within the Heteroptera, we found further autapomorphic patterns in Corixidae (Nepomorpha), Gerromorpha, and Leptopodomorpha. Finally, the Cimicomorpha and Pentatomomorpha share a special pattern of the two central rhabdomeres, which we call V-pattern. This is a new synapomorphy of these two taxa. Accepted: 22 November 1999     

The phylogenetic significance of the carpophore in Apiaceae

Background and aims

Fruit structural characters have traditionally been important in the taxonomy of the family Apiaceae. Previous investigations using a limited number of taxa have shown that the carpophore may be especially useful in helping to circumscribe subfamily Azorelloideae. The present study examines, for the first time, carpophore structure in 92 species from 43 genera, representing all subfamilies of Apiaceae, and including all genera assigned to subfamily Azorelloideae. Phylogenetic interpretations are made for the first time, using all available information, and a standard terminology is proposed to describe the various character states found in carpophores.

Methods

Carpophore structure was studied in detail using light microscopy.

Key Results

Carpophores, when present, may be categorized into two main groups (B and C) based mainly on the arrangement of the vascular bundles in transverse section, and further divided into six sub-types according to the length of the carpophore (short in B1 and C1) and whether they are entire (B1–B3 and C1) or bifurcate (B4 and C2). Free carpophores are absent in subfamily Mackinlayoideae, and in tribes Lichtensteinieae and Phlyctidocarpeae, which have two opposite vascular bundles (Group A). Entire carpophores with one or two vascular bundles, or bifurcate carpophores with lateral vascular bundles (arranged side by side within the commissural plane), are the main types characterizing Azorelloideae. The short, hygroscopic carpophores found in Choritaenia are unique in Apiaceae and provide additional evidence for the exclusion of this genus from Azorelloideae. Carpophore type C2 is typical for most Apioideae sensu lato (exceptions are, for example, Arctopus and Alepidea, which have type B2).

Conclusions

A single carpophore and ventral vascular bundles not forming free carpophores are proposed to be the ancestral conditions in Apiaceae, while bifurcate carpophores with opposite vascular bundles are the derived state, present in most Apioideae. Secondary reductions seem to have occurred in several unrelated lineages in all major groups, e.g. many Azorelloideae, several protoapioids (including nearly all members of the tribe Saniculeae) and 29 euapioid genera (e.g. some Oenantheae).     

The larval head of Raphidia (Raphidioptera, Insecta) and its phylogenetic significance

External and internal head structures of larval representatives of Raphidiidae are described. The obtained data were compared to characters of other neuropterid larvae and to larval characters of representatives of other endopterygote lineages. Characters potentially relevant for phylogenetic reconstruction are listed and discussed. The larvae of Raphidioptera differ distinctly from other neuropterid larvae in their morphology. They are mainly characterised by autapomorphic and plesiomorphic character states and few features indicate systematic affinities with other groups. Endopterygote groundplan features maintained in Raphidioptera are the complete tentorium, the free labrum, the full set of labral muscles, the presence of four extrinsic antennal muscles, the three-segmented labial palpi, the presence of a full set of extrinsic maxillary and labial muscles, the presence of a salivarium, and possibly the high number of stemmata. Apomorphies likely correlated with predaceous habits are the long gula, the protracted maxillae, the longitudinal arrangement of extrinsic maxillary muscles, and the elongated prepharyngeal tube. Highly unusual, potentially autapomorphic features are the presence of a dorsal ligament of the tentorium and paired gland-like structures below the pharynx. A prognathous or very slightly inclined head and slender mandibles without mola are features shared by larvae of all orders of Neuropterida. The parallel-sided head is a potential synapomorphy of Raphidioptera and Megaloptera. A fully prognathous head with anteriorly shifted posterior tentorial grooves and the presence of a parietal ridge and a distinct neck region are features shared with Corydalidae. Characters of the larval head are not sufficient for a reliable placement of Raphidioptera.