Biologia reprodutiva do caranguejo Goyazana castelnaui H. Milne- Edwards, 1853 (Crustacea: Trichodactylidae) no semiárido pernambucano

Abstract

The aim of this study was to analyze the biological characteristics of Goyazana castelnaui and evaluate whether the rainfall and water’s temperature influence the distribution and reproductive characteristics of the species. Were analyzed 87 individuals including 56 females (64.37%) and 31 males (35.63%), from September 2014 to August 2015 on a stretch of Pajeú River, located in Floresta/PE municipality. The sex ratio was 1♀: 0.6♂ along the months. Reproductive aspects of G. castelnaui were determined based on the macroscopic analysis of external and internal features and microscopic structures by observing the degree of development of germ cells. The macroscopic observation allowed to classify the specimens in seven stages. In juveniles the color of tergite ranged from gray to brown, the abdomen ranged in beige tones. The adults showed predominant wine color. The microscopic observation allowed to classify the female gonads in five stages that follow: Rudimentary (opaque white), early-maturing (light beige), maturing (dark beige to light orange), mature (dark orange), spawned maturing (transparent and/or gray). We indentified six cell stages of development: oogonia (diameter 32.9 ± 9.8 μm), pre-vitellogenic oocytes (96.8 ± 23.1 μm), oocytes in initial vitellogenesis (272.1 ± 12, 7 μm), vitellogenic oocytes (400.1 ± 12.1 μm), mature oocytes (884.4 ± 14.0 μm) and atretic oocytes. We also identified non germ components: follicular cells, hemal vessels, gonadal wall, vagina and seminal receptacle. For male, germ cells were classified in order of maturity as spermatogonia (18.15 ± 1.77 mm), spermatocytes (14.4 ± 1.39 mm), spermatids (8.83 ± 0.55 μm) and sperm (7.58 ± 0.55 μm). The macroscopic (color, size and shape) and microscopic aspects (presence of spermatophore in the posterior vas deferens and ducts) allowed to classify four stages of gonadal development. IRudimentary / immature; II - In maturation / Mature I; III - Mature/ Mature II; IV - Exhausted/spawned. The reproductive period G. castelnaui was classified as seasonal. Mature females were observed for a prolonged period, from August to February, most frequently between September and December. The onset of the rainy season (November) is the trigger for decline in spawning. The temperature rise in August coincided with the beginning of the spawning period, ending in February, there are strong indications of this species prefers to spawn during the summer. The females showed morphological maturity with LC50 of 3.17 cm (R² = 83.20). Although gonadal maturity occurred in smaller size, with LC50 of 2.84 cm (R² = 83.29). For males, there was the same trend, in which the morphological maturity occurred when individuals had an LC50 of 3.0 (R² = 76.19) and 2.84 cm (R² = 83.00), morphological and gonadal respectively. The final maturity for females and males occurred with LC99 of 3.85 cm (R² = 83.20) and 3.65 cm (R² = 76.19), respectively. However, the final gonadal maturity occurred first that the morphological, where the LC99 values obtained for both sexes were 3.51 cm (R ² = 83.29) and 3.52 cm (R ² = 83.00), respectively. In this study, the main features of the reproductive period G. castelnaui could be elucidated, considering the hypothesis of monophyly, and with strong indication that there is no segregation of the studied species, since all maturational stages were found.