Nicolau, C.F., Nascimento, A.A., Machado‐Santos, C., Sales, A. and Oshiro, L.M.Y. 2011. Gonads of males and females of the mangrove tree crab Aratus pisonii (Grapsidae: Brachyura: Decapoda): a histological and histochemical view. —Acta Zoologica (Stockholm) 00:1–9. This study describes the microscopic anatomy of the male and female gonads and the spermatogenesis and oogenesis of the mangrove tree crab Aratus pisonii. Males and females were captured in a mangrove marsh in Guaratiba (23°04′S, 44°10′W), Rio de Janeiro State, Brazil. The testes are composed of spermatogonia I (7.82 ± 0.84 μm), spermatogonia II (6.12 ± 0.72 μm), spermatocytes I (5.62 ± 0.71 μm), spermatocytes II (5.00 ± 0.42 μm), spermatids (4.01 ± 0.33 μm), and spermatozoa (2.58 ± 0.18 μm). The spermatozoids are sent to the vas deferens, which is divided into three regions: anterior vas deferens, middle vas deferens and posterior vas deferens. There are no indications of development as the production of male gametes was continuous throughout the study period. In the females, there are four ovary development stages: previtellogenesis, early‐stage vitellogenesis, mature vitellogenesis, and postspawning. Five types of cells were found in the gonads: oogonia (5.23 ± 1.31 μm), oocytes in early development (19.84 ± 5.16 μm), previtellogenic oocytes (49.49 ± 6.87 μm), vitellogenic oocytes (87.51 ± 10.23 μm), and mature oocytes (174.78 ± 29.46 μm). The findings of this study indicate that A. pisonii females lay eggs on multiple occasions throughout the study period.

ABSTRACT. Reproducti ve aspects of crab Ara/us pisonii (H. Milne Edwards) (Crustacea, Decapoda, Grapsidae) in ltacuruçá' s mangrove. The objective Oflhis work has to get know ledge about lhe reproducti ve aspect of the tree crab A ra/u.ç pisonii (H. M i I ne Edwards, 1837). The sampling were made monthly from April, 2000 to April, 2001, in the Itacuruçá' s mangrove (22°54'S and 43°33'W), Rio de Janeiro. The crabs were collected handly , using an effort of 50 minutes with three collectors. In laboratory, the specimens were separated by sex and had measured the carapace width and lenght. The ovigerous females were separated and the mass of eggs was removed for a mensurament of size and count of eggs. Afterwards, the animais were conservad in 70% alcohol. A total of 783 individuais were caught among 59% males and 41 % females among these 8% were ovigerous. The ovigerous females were found almost during the whole year, except in the winter showing major plenty on February and March , demonstrating the reproductive period. The ovigerous females presented size between 14.0 and 23.6 mm of carapace width and the average fecundity estimated to the specie was 9081 ± 3684 eggs. The mean size ofthe eggs was 0.27 mm varied from 0.24 to 0.29 mm and the size at onset of egg production was verified from 13 . 1 to 15 .0 mm of the carapace width. KEY WORDS. Ara/us pisol1ii, reproduction, tree crab, ltacuruçá's mangrove, Sepetiba Bay o litoral do estado do Rio de Janeiro é bastante recortado e composto por várias baías e enseadas, destacando-se entre elas a Baía de Sepetiba. A Baía de Sepetiba é importante por suas atividades de pesca e de turismo, comportando um importante manguezal da cidade de Itacuruçá município de Mangaratiba. Na Baía de Sepetiba, encontram-se os manguezais que constituem ecossistemas de transição, típicos de regiões tropicais e subtropicais, ocorrendo em zonas costeiras. É um ecossistema propício para reprodução e alimentação de muitas espécies an imais, sendo considerado transformadores de nutrientes em matéria orgânica (SCHA-EFFER-NOVELLl 1995). O manguezal da Baía de Sepetiba, abriga diversas espécies de crustáceos, principalmente os caranguejos da família Grapsidae, representada por

Os manguezais são ecossistemas de transição entre ambientes terrestres e marinhos típicos de regiões tropicais e subtropicais, sujeitos ao regime das marés e que ocorrem em zonas costeiras (SCHAEFFER -NOVELLI 1995). Segundo esse mesmo autor, os crustáceos decápodos apresentam uma fauna característica desse ecossistema, possuindo papel importante na cadeia alimentar, decomposição de matéria orgânica e bioturbação do solo.Nos manguezais da Baía de Sepetiba foi observado um total de cinco espécies de Grapsoidea, sendo uma da família Grapsidae -Goniopsis cruentata (Latreille, 1803) -e outras quatro da família Sesarmidae: Aratus pisonii (H. Milne Edwards, 1837); Sesarma rectum Randall, 1840; Chasmagnathus granulata Dana, 1851; e Armases rubripes (Rathbun, 1897) (= Metasesarma rubripes) (OSHIRO et al. 1998).Aratus pisonii é um caranguejo que apresenta hábito arborícola, sendo encontrado em ramos e troncos das árvores de manguezal (WARNER 1967 for population structure studies and by seasonal sampling from January to October 2002 for space and seasonal distribution studies, dividing the mangrove in three different areas. On the space-seasonal distribution study, 694 crabs were caught, where 45% was captured in area 1,36% in area 2 and 19% in area 3. There were significant differences between the number of individuals between area 2 and 3. For the population structure study a total of 742 crabs were captured, being 59% male, 32.7% female and 8.3% ovigerous females. The sex ratio was 1:0.69 (male:female), and the carapace width ranged from 9.6 to 25.0 mm CW in males and from 5.5 to 24.9 mm CW in females. The size class distribution was unimodal and the males were more frequent between 19.1 to 21.0 mm CW, while females between 17.1 to 19 mm CW. The sex ratio along each size class showed the male predominance in almost all classes except between the classes of 5.1 to 7.0 and 7.1 to 9.0 mm CW. KEY WORDS. Populational biology; Sepetiba Bay; sex-ratio; tree crab.RESUMO. Este trabalho teve por objetivo analisar a distribuição espacial e sazonal e a estrutura populacional do caranguejo arborícula Aratus pisonii (H. Milne Edwards, 1837). O trabalho foi realizado através de coletas mensais de junho de 2000 a maio de 2001, para estudo da estrutura populacional e coletas sazonais de janeiro a outubro de 2002 para o estudo da distribuição espacial e sazonal, dividiu-se o manguezal em três áreas. Para a distribuição espacial e sazonal foram capturados 694 indivíduos sendo 45% na área 1, 36% na área 2 e 19% na área 3. O número de indivíduos apresentou diferença significativa na distribuição espacial entre as áreas 2 e 3. Para o estudo da estrutura populacional foi capturado um total de 742 caranguejos, sendo 59% machos, 32,7% fêmeas e 8,3% fêmeas ovígeras. A razãosexual obtida foi de 1: 0,69 (macho:fêmea) e a largura da carapaça variou de 9,6 a 25,0 mm em machos e de 5,5 a 24,9 mm em fêmeas. A distribuição da freqüência em classes de tamanho foi unimodal e os machos foram mais freqüentes entre as classes de 19,1 a 21,0 mm LC, enquanto ...