摘要:

The ultrastructure of the frontal gland complex of six species of Macrostomida is investigated. In all species it comprises an array of discretely emerging gland necks of at least two gland types, including one with rhammite secretion granules and one with rhahdite granules. Moreover, mucous glands and glands containing other secretion granules are found in Microstomum sp. No intermeditate form which would allow bridging of the present lack of ultrastructural, histochemical and positional similarities between the Macrostomida and the Acoela is found in the examined species. Therefore, the probability of homology between the frontal organs of the Acoela and the frontal glands of the Macrostomida remains low. Even though two or three tyes of sensory receptors are found distributed over the anterior end of all examined species, the frontal gland complex does not appear to be sensory. Because of the uniformity in frontal gland ultrastructure. relationships within the Macrostomida based on this character alone cannot be detected.

ISSN:0300-3256    

DOI:10.1111/j.1463-6409.1987.tb00057.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Comparative ultrastructural observations were carried out on the spermiogenesis of the capsalidCaballerocotyla manteriPrice and the dionchidDionchus remoraeMacCallum. At the beginning of spermiogenesis the zones of differentiation (ZD) jut out in all directions. A large mitochondrion shaped like a perforated bead, and through which the elongated nucleus passes, is found facing each ZD. Later the ZD become parallel and are embedded within the common cytoplasmic mass. Cortical longitudinal microtubules are present in the ZD at the outset of spermiogenesis, but they later disappear. The spermatozoon is long and filiform. It shows two parallel axonemes of the 9 +“1” flatworm pattern, the nucleus and mitochondrion, and no cortical microtubule. The ultrastructure of spermiogenesis and spermatozoon is remarkably similar in the two species studied, as in other capsalids previously described. Two characteristics, the perforated bead shape of the spermatid mitochondrion and the progressive disappearance of the microtubules of the ZD, may be considered as synapomorphies which indicate close phylogenetic relationships between the families Dionchidae and Capsalidae. This interpretation coincides with Llewellyn's (1971) scheme of the evolution of the monogene

ISSN:0300-3256    

DOI:10.1111/j.1463-6409.1987.tb00058.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

The type of material ofMonhystrella parvella(Filipjev, 1931) comb.n. from Abyssinia (Ethiopia) is redescribed and figured in detail. Data on the genital system and the ontogeny of this species are given.Monhystera filiformis sensuGerlach, 1951necBastian, 1865 of the Black Sea at Pomorie (Bulgaria) is synonymised withM. parvella. The Black Sea specimens have a shorter pharynx, a longer tail and differ also from the Abyssinian specimens in the shape of the tail and the spinneret outlet.

ISSN:0300-3256    

DOI:10.1111/j.1463-6409.1987.tb00059.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Six new species of the genusRichtersiaSteiner, 1916 are described from the Mediterranean Sea:R. bathyalissp.n.,R. spinosasp.n.,R. heipisp.n.,R. mediterraneasp.n.,R. staresensissp.n. andR. coomansisp.n. Some morphological adaptations ofR. bathyalis, R. spinosaandR. heipiare discussed in relation to their small body size. The structure of the stomatal region, labial region and spicules is described in detail and probably holds for the entire genus.

ISSN:0300-3256    

DOI:10.1111/j.1463-6409.1987.tb00060.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Large populations ofTigriopusare reported from the Kerguelen Islands and Crozet Islands in the South Indian Ocean. The two populations exhibit complete sexual isolation, strong genetic differentiation and different karyological patterns. The description of these two new species points out only very slight morphological differences and they may be considered as sibling species. Distribution and status of the nine species ofTigriopusactually known are discussed.

ISSN:0300-3256    

DOI:10.1111/j.1463-6409.1987.tb00061.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Leptastacus laticaudatusNicholls, 1935, commonly found interstitially in fine sands of European boreal waters, is redescribed and figured. As a result, the subspecies namesL. laticaudatus laticaudatusandL. laticaudatus intermediusKunz, 1938 are nullified. Some variable characters, i.e. caudal rami and structure of the fifth leg, are discussed and the distribution of the species is summarized. The most closely allied speciesL. macronyx(T. Scott, 1892) andL. spatulisetaMielke, 1982 constitute, together withL. laticaudatus, the‘macronyx‐group’.L. laticaudatus intermedius sensuApostolov, 1973 is consideredspecies inquirenda. An amended diagnosis of the genusLeptastacusT. Scott, 1906 is pres

ISSN:0300-3256    

DOI:10.1111/j.1463-6409.1987.tb00062.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Evolution has led to changes in the gross anatomy of the arthropod hearts. Changes are also seen in the ultrastructural organization of the cardiomyofiber. Thus the myofilament organization and the membrane systems (T‐system and SR) vary within both Chelicerata, Crustacea and Uniramia. Yet, the variation is not haphazard, but constitutes a pattern which cannot be deduced from the gross anatomy. In the three taxa the evolutionary tendency seems to be towards a more strict sarcomeral organization of the myofilaments. This is due to parallelism. The organization of the membrane systems and the spatial relation of the interior couplings are not identical for all arthropods. However, no variations has so far been detected within one and the same order, despite differences in adaptation and size. These systems are conservative and it is suggested that they could be useful in studies of arthropod phylogen

ISSN:0300-3256    

DOI:10.1111/j.1463-6409.1987.tb00063.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Neoxerisgen.n. (type species:Neoxeris melanocephalasp.n.) from India is described and illustrated.Neoxerisis related toSirexLinnaeus andXerisCosta from which it is distinguished. A revised key to the world genera of Siricinae is provided.

ISSN:0300-3256    

DOI:10.1111/j.1463-6409.1987.tb00064.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY