Paula Beatriz Araujo

An assemblage of terrestrial isopods (Crustacea) in southern Brazil and its contribution to leaf litter processing

We present an assemblage of terrestrial isopods in Parque Estadual de Itapua, southern Brazil, and estimate the contribution of two species to the leaf litter processing. After one year of sampling, we obtained 3748 individuals of six species and four eco-morphologic groups (in order of abundance): Balloniscus glaber Araujo & Zardo, 1995, Atlantoscia floridana (van Name, 1940), Pseudodiploexochus tabularis (Giambiagi de Calabrese, 1939), Trichorhina sp., Alboscia itapuensis Araujo & Quadros, 2005 and Novamundoniscus gracilis Lopes & Araujo, 2003. Total monthly density corresponded to 368 individuals per square meter. The species A. itapuensis and N. gracilis represented less than 1% of total individuals. All the others showed aggregated distribution. Atlantoscia floridana and B. glaber had the highest proportion of individuals occurring together (88%) and a significant species association. Their monthly biomass averaged 4.92 kg ha-1 for B. glaber and 0.97 kg ha-1 for A. floridana. Consumption rates, obtained in the lab (in mg mg-1 day-1) were 0.34 ± 0.04 and 0.70 ± 0.18 for B. glaber and A. floridana, respectively and assimilation efficiency was about 30%. We estimated that both species together could process 860 kg leaves ha-1 year-1.

TWO NEW SPECIES OF HYALELLA FROM SOUTHERN BRAZIL (AMPHIPODA: HYALELLIDAE) WITH A TAXONOMIC KEY

Abstract The freshwater amphipod genus Hyalella in Brazil has the second highest diversity in South America; it is only surpassed by the diversity found in the Andean Lake Titicaca. Ten species of Hyalella are known for Brazil: H. gracilicornis (Faxon, 1876); H. longistila (Faxon, 1876); H. warmingi Stebbing, 1899; H. meinerti Stebbing, 1899; H. curvispina Shoemaker, 1942; H. brasiliensis Bousfield, 1996; H. caeca Pereira, 1989; H. montenegrinae Bond-Buckup and Araujo, 1998; H. pseudoazteca González and Watling, 2003; and H. dielaii Pereira, 2004. Two new species are described here, H. castroi and H. pleoacuta, both occurring in freshwater bodies of southern Brazil over 1.200 m high in the region of Aparados da Serra. A key for the species of Hyalella from Brazil is presented.

Diversity and arrangement of the cuticular structures of Hyalella (Crustacea : Amphipoda : Dogielinotidae) and their use in taxonomy

This study describes the morphology and arrangement of the cuticular structures of Hyalella castroi Gonzalez, Bond-Buckup & Araujo, 2006 and Hyalella pleoacuta Gonzalez, Bond-Buckup & Araujo, 2006, to identify specific characters that can be used in taxonomstudies of this genus. The entire cuticular surface of both species was examined by optical and scanning electron microscopy. The data obtained were compared with available information for other members of Peracarida, mainly Amphipoda and Isopoda. Five different types of cuticular structures, including 30 types of setae, four types of microtrichs, three types of pores, and some structures formed by setules and denticles were identified. The results were compared with other groups of gammarids, and peracarideans, such as Thermosbaenacea and Isopoda. The use of cuticular structures as a tool for taxonomic studies showed important results, not only at species level, but also at genus, and family levels.

Description of the Agonistic Behavior of Aegla longirostri (Decapoda: Aeglidae)

Abstract Among animals, conflicts are resolved through agonistic behavior, an expression of which embraces a range of fleeing behaviors, displays, up to the extreme of physical combat. This study aims to establish an observation protocol and to describe the aggressive acts of Aegla longirostri. Aeglids were collected in the field and kept for one week of acclimation in individual fishbowls with no contact with other animals. A total of ten pairs of males were paired, the members of each pair differing by no more than 1 mm in cephalothorax length. The behavioral acts were described from the combats videotaped for 20 minutes with each pair, of which 16 were considered aggressive acts. The animals took an average of 198 seconds to start combat. A table of aggression intensity was established, ranging from −2 (fleeing) to 5 (intense combat). There was a significant difference between winners and losers in the time spent in the different levels of intensity and in the duration of the acts performed. Aegla longirostri showed very intense aggression with defined aggressive acts and continued to engage in agonistic behavior for the entire duration that was recorded. This is the first report of aggressive behavior in aeglids, it will be possible to carry out more profound studies on the behavior of these animals.

Terrestrial isopod diversity in the subtropical Neotropics: Itapuã State Park, southern Brazil

We analysed species abundance and composition during one year of sampling at Itapua State Park, a conservation unit in the State of Rio Grande do Sul, southern Brazil. Samples were collected monthly from May 2003 to April 2004 along a 4 km forest trail divided in three transects along the slopes of a small hill. Terrestrial isopods were hand searched by three people for 40 minutes at two sampling sites along each transect, summing 240 minutes of sampling effort per transect per month. Six species distributed in six families were found. The collector curve stabilised when half the samples were taken, demonstrating sampling sufficiency: analytical estimates did not predict more species to be found in the trail. Atlantoscia floridana (van Name, 1940) was dominant in all transects. Abundance varied along the year with a summer and a winter peak, but peaks were not consistent among transects. The first part of the trail, used for ecotourism, was less diverse, had less species (4 as compared to 6 in the other transects), and was thus also less similar in composition.

Checklist of the Crustacea from the state of Santa Catarina, Brazil

The list of Crustacean species from the state of Santa Catarina, southern Brazil, comprises 518 valid species, distributed in 17 orders and 152 families. This amount corresponds to 0.75% of the Crustacea worldwide and about 20% of Brazilian species. The order Decapoda is the most represented, with 280 species. The families of Decapoda with the greatest number of species recorded were: Aeglidae (19), Palaemonidae (13) and Portunidae (13). In addition, the occurrence of 19 species distributed in the orders Cyclopoida (1), Podocopida (2) and Decapoda (16) is reported for the first time. Exotic species (9) are distributed in four different orders - Isopoda (6), Calanoida (1), Thoracica (1) and Decapoda (1).

Postmarsupial development of Atlantoscia floridana (van Name, 1940) (Crustacea, Isopoda, Oniscidea): the manca stages

In this paper we describe the postmarsupial development of the manca stages of Atlantoscia floridana (van Name, 1940). Ovigerous females were collected in Reserva Biológica do Lami, Porto Alegre, RS, Brazil and separately reared in small containers at 20°C (±1°C). After birth each newborn (manca I) was reared separately in order to observe the subsequent moults. In a period of about 12 h the animals underwent the first moult. The manca II stage lasts 9.16±1.57 days while manca III takes up a period of 9.96±1.05 days. Growth was observed through measurements of cephalothorax width. The three manca stages are described, illustrated and compared with the adults. The main distinguishing characteristics among mancas I, II and III are presented as well as the b/c and d/c co-ordinates of the noduli laterales.

The manca stages of Porcellio dilatatus Brandt (Crustacea, Isopoda, Oniscidea)

This paper presents the description of the three manca stages of the terrestrial isopod Porcellio dilatatus Brandt, 1833 (Porcellionidae). Ovigerous females were collected and kept in the laboratory under controlled conditions (23°C ± 1°C and 14:10 h light:darkness). After birth, mancas (M) were individually reared, and their development was observed. Stages M I, M II, and M III were described based on general characteristics, ommatidia, and appendages. The average development time of each stage was: M I = 18.7 ± 1.5 h (n = 52), M II = 12.7 ± 1.19 days (n = 101), and M III = 12.7 ± 0.45 days (n = 24). Growth was observed using measurements of cephalotorax width. The main characteristics of each stage are presented.

Growth curve of Atlantoscia floridana (van Name) (Crustacea, Isopoda, Philosciidae) from a Brazilian Restinga Forest

The terrestrial isopod Atlantoscia floridana (van Name, 1940) occurs from the U.S.A. (Florida) to Brazil and Argentina. In the southernmost Brazilian State, Rio Grande do Sul, the species is recorded in many localities, in urban and in non-urban areas. The growth curve of Atlantoscia floridana based on field data is presented. The specimens were sampled from April, 2000 to October, 2001 at the Reserva Biologica do Lami (RBL), Rio Grande do Sul. Captured individuals were sexed and had their cephalothorax width measured, with the data analyzed with von Bertalanffys model. The growth curves for males and females are described, respectively, by the equations: Wt = 1.303 [1 - e-0.00941 (t + 50.37)] and Wt = 1.682 [1 - e-0.00575 (t + 59.13)]. The curves showed differential growth between sexes, where females reach a higher Wµ with a slower growth rate. Based on the growth curves it was also possible to estimate life expectancy for males and females.

Postmarsupial development of Atlantoscia floridana (van Name, 1940) (Crustacea, Isopoda, Oniscidea): sexual differentiation and size at onset of sexual maturity

Summary The postmarsupial development of Atlantoscia floridana (van Name, 1940) was studied, with emphasis on the sexual differentiation and maturity. Samples were obtained in the Reserva Biológica do Lami, Porto Alegre, RS, Brazil, during 2000 and 2002. Collected animals were reared in the laboratory under temperatures of about 20±1°C and observed daily. Animals preserved in 70% ethanol were used to analyze sexual maturity. Growth was monitored as each animal moulted for evidence of sexual differentiation. The development of the male genitalia and the female genital pore was described across the different juvenile stages. Female sexual maturity was estimated to occur at a minimum size of 1.04 mm cephalothorax width. Male sexual maturity was estimated from the morphometric relationship between cephalothorax width and length of the genital papilla and indicated the puberal moult to occur at a minimum size of 0.77 mm cephalothorax width. Identification of the size at which sexual maturity occurs allows recognizing the postmarsupial juvenile stages of both males and females: JUI to JU III for males and JU I to JU VI for females. Males reach sexual maturity in approximately 1.5 months after leaving the marsupium, and females in about 3 months.