Myxomycetes occurring on Cecropia adenopus ( Cecropiaceae ) in fragments of Atlantic Rainforest

(Myxomycetes occurring on Cecropia adenopus (Cecropiaceae) in fragments of Atlantic Rainforest). Cecropia adenopus (Ambay pumpwood) is a frequent native species on the edges of woods and clearings and is considered a pioneer species in re-colonized areas. Despite its distribution from Mexico to Argentina, this substrate has never been examined in detail regarding the presence of Myxomycetes. In the present study, the myxobiota associated with leaf debris of C. adenopus was investigated in two Atlantic Rainforest conservation units located in the Brazilian state of Rio Grande do Norte. Five specimens and one plasmodium were obtained directly from the fi eld and 87 were developed in 43.7% of 200 moist-chamber cultures set up separately with blades and petioles. Fift een species were identifi ed and illustrated. Th e two predominant groups were representatives of Trichiales and Physarales. Didymium columella-cavum was recorded for the second time in Brazil and in the world.

A number of studies have addressed the association of myxomycetes with phanerogam families, genera and species, such as living or decomposing palm trees (Mobin & Cavalcanti 1998/1999;2000;Cavalcanti & Mobin 2004;Stephenson 2003) and species of Quercus L. (Wrigley de Basanta 1998), Rizophora L. (Stephenson 1988) and Terminalia L. (Bezerra & Cavalcanti 2007).Some of these studies have been conducted in northeastern Brazil with introduced species employed in urban tree-planting programs or native species found in diff erent ecosystems.
Th e Ambay pumpwood (Cecropia adenopus Mart.ex Miq.) is a native species frequently found on the edges of woods and clearings, distributed from Mexico to Argentina and appearing in greater abundance in the Amazon region.It is considered a pioneer species in re-colonized areas.It belongs to the Cecropiaceae family, which encompasses six genera and 170 species and is characterized by a hollow, curly stem that ants (myrmecophila) use for shelter; spiral phyllotaxis; peltate, palmatilobed leaves, divided radially; and long petioles with a glandular pulvinule at the base (Braga 1953).
Leaves and fruit from the Ambay pumpwood are used in folk remedies for the treatment of diabetes as well as for coughs and bronchitis.Th e juice extracted from the root is a powerful diuretic.Juice from the buds is oft en used in the treatment of diarrhea, gonorrhea and is employed by indigenous peoples on wounds produced by venomous insects.Ash from the stem is used to whiten clothes, make soap and purify sugarcane sap in the fabrication of sugar.In Brazil, the plant is normally known as "imbaúba", originating from the term "ambaíba" from the indigenous Tupi language, meaning "tree with orifi ce" or "tree that does not serve for construction" (Braga 1953).
In studies on the soil and shoot debris carried out on the myxobiota in Atlantic Rainforest conservation units on the coast of the state of Rio Grande do Norte (Brazil), greater attention has been given to this species due to the frequent occurrence of myxomycetes on its leaves and branches.
Th e other sampling area was the Natal Dunes State Park (05 o 48'S -05 o 53'S and 35 o 09"W -35 o 12"W, 1,172.80ha, 80 -120 m alt.), the second largest urban park in Brazil, located in the city of Natal, Rio Grande do Norte.Th e climate is humid, with annual precipitation of 1200 mm.Th e park contains formations of dunes densely covered by sub-humid Atlantic Rainforest and a small stretch of the coastal tablelands (Freire 1990).It has large trees forming a canopy approximately 20 meters in height, with C. adenopus individuals in the lower arboreal stratum, particularly in more illuminated locations, such as the entrance of the Perobinha trail.

Collection, culturing and analysis of myxobiota
Myxomycete sporocarps were collected from branches and dead leaves (either fallen on the ground or stuck in bushes approximately 2 m above the ground) of C. adenopus (Figs.1-3) individuals distributed in the interior and along the trails of the study areas between June 2004 and September 2006.Two hundred moistchamber cultures were set up, with blades and petioles placed in disposable Petri dishes (9 cm) lined with sterilized filter paper soaked in distilled water.The cultures were maintained at room temperature (22º to 25ºC) and examined on a weekly basis for a period of three months with the aid of a stereomicroscope (Schnittler & Stephenson 2002).Exsiccates representative of the material obtained in the fi eld and laboratory were deposited in the UFP Herbarium of the Pernambuco Federal University.Identification of the specimens was based on morphological characters, following descriptions by Lister (1925), Martin & Alexopoulos (1969), Farr (1976), Lado & Pando (1997) and Mitchell (2004).Illustrations were based on the collected material.Taxonomic nomenclature and abbreviations of the names of the authors follow Hernández-Crespo & Lado (2005).On eight expeditions to the study areas between 2004 and 2006, five specimens and one plasmodium were obtained directly from the fi eld on C. adenopus leaves that had fallen to the ground and 87 specimens were developed in 43.7% of the moist-chamber cultures set up separately with blades and petioles.On these collections, 10 genera and 15 species were represented, most belonging to Physarales (47%) and Trichiales (33%).In the cultures set up with leaf blades, H. pardina, 8;11), representing 80.5% of the specimens.More than half (60%) of the species were recorded only once either in the fi eld or in the laboratory.Most of the species recorded in the present study are commonly cited as foliicolous, except Arcyria cinerea (Fig. 4), which does not have a substrate preference.