Lectotypifications of six taxa in the Boraginales (Cordiaceae and Heliotropiaceae).

A large number of specimens used as original material for the description of new species were destroyed in the bombing of the Berlin-Dahlem herbarium, B, in 1943. Six lectotypes are designated here for Cordia discolor Cham., Cordia multispicata Cham., Cordia tobagensis Urb. and its variety broadwayi Urb. in the Cordiaceae and for Tournefortia paniculata Cham. and Tournefortia ulei Vaupel in the Heliotropiaceae.

Two new combinations in Euploca Nutt. (Heliotropiaceae, Boraginales) and a conspectus of the species of the Guiana Shield area.

Heliotropium foliatum and Tournefortia humilis are transferred to Euploca Nutt. respectively as Euploca foliata comb. n. and Euploca humilis comb. n. A collection from Guyana has been recently identified as Euploca humistrata, a species previously considered a Brazilian endemic. A collection from French Guiana documents for the first time the species in that country. A key to the species of the Guiana Shield area is given. The species of Euploca from the Guiana Shield are listed with synonymy and a brief description: Euploca filiformis, Euploca humilis, Euploca humistrata, Euploca lagoensis, Euploca polyphylla, Euploca procumbens.

The typification of Cordia flavescens Aubl., the transfer of Firensia Scop. from Cordia L. (Cordiaceae, Boraginales) to the synonymy of Ocotea Aubl. (Lauraceae), and the identity of the species of Firensia.

Firensia Scop. was based on Cordia flavescens Aubl., a species described and illustrated from a mixed collection that Scopoli never transferred to Firensia. The genus included three additional species formally named by Rafinesque. Currently the four species are placed in three different families and none retained the epithet accepted by Scopoli or given by Rafinesque for reason of priority. A lectotype is designated for Cordia flavescens that places Firensia in the synonymy of Ocotea (Lauraceae).

Two new species of Dilkea subgenus Dilkea (Passifloraceae) from Loreto, Peru.

Two new species of Dilkea subgenus Dilkea (Passifloraceae) are described from Loreto, Peru. Dilkea hebes Feuillet, sp. nov., has leaves with elliptic to oblanceolate blades that are dull adaxially, and spherical fruits with thick walls; Dilkea nitens Feuillet, sp. nov., has leaves with narrow-ovate blades that are shiny adaxially, and fruits with an apical cone and thin walls. A key to the species of subgenus Dilkea is provided.

Reelin signaling is necessary for a specific step in the migration of hindbrain efferent neurons.

The cytoarchitecture of the hindbrain results from precise and co-ordinated sequences of neuronal migrations. Here, we show that reelin, an extracellular matrix protein involved in neuronal migration during CNS development, is necessary for an early, specific step in the migration of several hindbrain nuclei. We identified two cell populations not previously known to be affected in reeler mutants that show a common migratory defect: the olivocochlear efferent neurons and the facial visceral motor nucleus. In control embryos, these cells migrate first toward a lateral position within the neural tube, and then parallel to the glial cell processes, to a ventral position where they settle close to the pial surface. In reeler mutants, the first migration is not affected, but the neurons are unable to reach the pial surface and remain in an ectopic position. Indeed, this is the first evidence that the migration of specific hindbrain nuclei can be divided into two parts: a reelin-independent and a reelin-dependent migration. We also show that reelin is expressed at high levels at the final destination of the migratory process, while the reelin intracellular effector Dab1 was expressed by cell groups that included the two populations affected. Mice mutant at the Dab1 locus, called scrambler, exhibit the same phenotype, a failure of final migration. However, examination of mice lacking both reelin receptors, ApoER2 and VLDLR, did not reveal the same phenotype, suggesting involvement of an additional reelin-binding receptor. In the hindbrain, reelin signaling might alter the adhesive properties of efferent neurons and their ability to respond to directional cues, as has been suggested for the migration of olfactory bulb precursors.