Les otolithes des Téléostéens du Plio-Pleistocène belge

The study of approximately twenty three thousand otoliths from Plio-Pleistocene sites in the harbour region of Antwerp, as well as a critical revision of already published material allowed us to identify a teleostean fauna with fourty seven species (including two subspecies and seven species in open nomenclature). Two of these, Ophidion springeri and Uranoscopus septentrionalis are new to science. The fauna is typical for coastal waters slightly warmer than those of the actual North Sea and caracterized by the predominance of Gadidae. Biostratigraphically this fauna is well individualized with respect to preceeding ones (only seven species in common with the Miocene fauna) and those following twenty-three species in common with the extant fauna). The following biostratigraphical subdivision has been recognized in the Upper Miocene and the Plio-Pleistocene of the Antwerp region: (1) an association with «genus? Macrouridarum labiatus, Trisopterus sculptus, Gadiculus benedeni and Trisopterus luscus spectabilis, in the Sands of Deurne (Upper Miocene); (2) an association with Gadiculus benedeni and Merlangius pseudaeglephinus, in the Formation of Kattendijk (Pliocene); (3) an association with Gadiculus verticalis and Merlangius pseudaeglefinus in the Formation of Lillo (Plio-Pleistocene); (4) an association with Gadus morhua and Merlangius pseudaeglefinus in the so called «Icenian deposits not present in Belgium but found in the Netherlands.     

Holmesopteris faironiae,fougère nouvelle du Carbonifère supérieur des Monts Cantabriques (NW de l'Espagne) et de Belgique

Isolated fern rachises have been discovered in twoWestphalian A coal balls of Belgium and Spain. They represent a new taxon, Holmesopteris faironiae n.gen., n.sp., characterized by the special location of the protoxylem poles. The morphology, the anatomy and the foliar branching of this new taxon suggest that it may belong to the family Botryopteridaceae; Stephanian species of the genus Botryopteris seem closely related to the new fern.     

L’origine et l’évolution des éléphants

Origin and evolution of proboscideans. Recent palaeontological research has significantly enhanced our knowledge of the evolution of proboscideans, especially the beginning of their evolutionary history. New discoveries in the Early Eocene support, in particular, a lophodont ancestral morphotype for the Proboscidea and the African origin of the order, from which the Asiatic Anthracobunidae are excluded. The primitive Eocene proboscideans remain, however, poorly known. Other important discoveries have been made on the question of the origin of the moeritheres, of the deinotheres and elephantimorphs, and on the differentiation of elephantids. Palaeontology demonstrates in the Proboscidea a remarkably rich history, unsuspected from the extant relictual diversity, and one of the most spectacular morphological evolutions in the Mammalia.     

Premiers résultats de l'élevage des larves d'un Hyménoptère chalcidien (Pteromalus puparum l.) sur hémolymphe de Lépidoptère

Summary Isolated larvae of the parasitic wasp,Pteromalus puparum, were reared in a hanging drop on the haemolymph of diapausing pupae of their natural host,Pieris brassicae. A high mortality was observed, but, in a few cases, the complete development was obtained. The weight of the larvae was evalued according to their calculated volume, and their growth curves were compared to that of normally fed larvae. Among the artificially reared larvae, various types of development were observed and most of them appeared to enter into diapause. The high mortality and the variability of larval growth may be attributed either to the poor quality of the food, or to the bad physical conditions offered to the larvae.      

Faunistique et répartition longitudinale des Trichoptères dans une rivière salmonicole de basse montagne,en Belgique

Trichoptera have been studied in the drainage basin of the Flavion, a small calcium-ion rich low altitude trout river in Belgium. During a one-year investigation, 45 species, which represent one fourth of the recorded Belgian Trichoptera, have been collected. As a whole, the caddis larvae show a rather weakly defined zonation. Longitudinal distribution of closely related species is discussed from the standpoint of interspecific competition.

     

Les recherches sur les lépidoptères foreurs des graminées et leurs antagonistes : bilan et perspectives

Ancistrocerus, Discoelius and Symmorphus are xylicolous predatory wasps, the former two genera hunting caterpillars, the last one using both caterpillars and larvae of Chrysomelidae beetles. One of the aims of this study was to compare the stinging pattern of species from these genera with the ancestral “complete four-sting pattern” (C4SP) and reduced “two-sting pattern” (C2SP). Another aim was to clarify whether stinging pattern of predatory wasps depends mostly on the prey type or on the systematic position of the wasp. Sting traces on 6123 paralysed prey specimens, taken from 409 fresh wasp nests made by 10 wasp species in reed (Phragmites australis) trap-nests in three localities of Lithuania, were studied. The total number of stings applied to a prey specimen, the number and the share of stings directed to its body segments and the probability of stinging the segments were considered. The main conclusions of the study are: (1) the total number of stings delivered to a prey is species-specific, in some cases it may be used to distinguish fresh nests of related wasp species, as those of Symmorphus crassicornis and S. murarius and those of Discoelius dufourii and D. zonalis. (2) The distribution of stings is significantly different from the basic patterns C4SP and C2SP in all ten studied wasps; however, four caterpillar-hunting species have the distribution close to the C2SP The stinging pattern of three Symmorphus species hunting Chrysomelidae larvae included regular stings to the throat, three thoracic and the first abdominal segment; it could be abbreviated as C5SP (a complete five-sting pattern). (3) The distribution of stings among the segments of prey was found to be more dependent on the taxonomic position of the wasp species than on the prey type, thus it might be used as a behavioural character in comparative and phylogenetic studies. (4) The stinging pattern depended on the prey type as well: in the caterpillar-hunting S. debilitatus, it was quite different from the stinging pattern of the Symmorphus that hunt Chrysomelidae larvae.     

Présence d'une gouttière de l'obturateur externe chez quelques Cercopithécoïdes et Platyrrhiniens

The presence of the obturator groove in the atelines and the hominoids is thought to be caused by the pressure of the active muscle obturator externus against the femoral neck during extension of the hip. However, the presence of an obturator groove is common in some Cercopithecoids and Platyrrhines who rarely extend the hip during their usual posture and locomotion. The functional significance of this groove is called into question, especially in some Cercopithecoids, with reference to a hip dissection of Macaca. It is suggested that the presence of the groove can also indicate a hip frequently flexed.     

Etude du vieillissement d’Anagallis arvensis L.: Action régulatrice de la lumière,du saccharose et de l’acide indolyl-acétique sur la capacité rhizogènique des feuilles et des rameaux axillaires

The rooting capacity of leaves isolated from a vegetative clone ofAnagallis arvensis L. exposed to 9 hours of light (75 W m⁻²) at 22 °C and 15 hours of dark at 12 °C a day is significant only in F₁ young leaves and not in adult ones. The rooting capacity of the young leaves and of the vegetative shoots is greater in longer photoperiods. The leaves make roots even under weak (14 W m⁻²) irradiance. The rooting capacity of the leaves is diminished and even suppressed by exogenous sucrose (14,60 ×10⁻³M). This inhibition may be counteracted by IAA (10⁻⁶M). When leaves and shoots are taken from clones under long (16 h) photoperiods, or in constant irradiance, they progressively lose their rooting capacity during the treatment. Rooting capaoity is regained if the clones are returned again to “short day” (9 h) condition.      

Système Sétifère des Maxillipèdes de Squilla mantis (Crustacea,Stomatopoda): Morphologie fonctionnelle

Résumé Les maxillipèdes de Squilla mantis comprennent 5 types fondamentaux de soies et un type de formation pseudosétale, représenté par des tubercules plissés sur les propodites des 5 maxillipèdes.Parmi les différents types de soies, 2 sont caractéristiques des Stomatopodes et 3 représentent des catégories sétales évolutives existant également dans d'autres groups de Crustacés.La distribution des soies montre que les premiers maxillipèdes, définis comme pattes nettoyeuses, sont les plus spécialisés dans la réception sensorielle (mécanique et chimique).

---

Setal system of maxillipeds of Squilla mantis (Crustacea, Stomatopoda): Functional morphology

Summary There are 5 basic setal types in the maxillipeds of Squilla mantis (Stomatopoda) and 1 type of pseudosetal formation, represented by folded tubercles on the propodites of the 5 maxillipeds.Among these setal types, 2 are typical of Stomatopoda, and 3 represent evolutive setal categories also present in other groups of Crustacea.Their distribution shows that first maxillipeds, defined as grooming appendages, are the most specialized in sensorial reception (mechanical and chemical).

     

La respiration tissulaire des branchies des Téléostéens d'eau douce

Sans résumé