ABSTRACT
Polydesmida is the largest order in the class Diplopoda in terms of the number of species, genera and families, but there are few studies of the ovarian morphology of species in this order. This study aimed to perform a comparative study of the ovarian morphology of three species from this order to increase the understanding of the morphological evolution of this system in Polydesmida. Adults females of two of these species, Poratia salvator and Myrmecodesmus hastatus, belonging to the family Pyrgodesmidae, had a unpaired ovary that formed a tubular organ containing oocytes, with P. salvator present grouping of oocytes into a structure similar to ovisacs. This condition appeared to be apomorphic and was associated with the small size of these species ( 10 mm) and their short life cycle. The third species, Telonychopus klossae (Chelodesmidae), had a large body and an ovary with paired ovisacs, which was symplesiomorphic with other Polydesmida families.
A ordem Polydesmida é a maior da classe Diplopoda em número de espécies, gêneros e famílias, entretanto existem poucos estudos sobre a morfologia ovariana de suas espécies. Esta pesquisa tem como objetivo realizar um estudo comparativo sobre a morfologia ovariana de três espécies dessa ordem a fim de contribuir para discussões sobre a evolução morfológica deste sistema no grupo. Duas dessas espécies, Poratia salvator e Myrmecodesmus hastatus, representantes da família Pyrgodesmidae, apresentam ovário como um órgão tubular único, com a primeira possuindo os ovócitos agrupados em uma estrutura semelhante a ovissacos. Esta condição parece ser uma apomorfia aparentemente associada ao tamanho diminuto dos animais destas espécies (menos de 10 mm) e suas histórias de vida curtas. A terceira espécie, Telonychopus klossae, um quelodesmídeo de tamanho corporal grande, possui um ovário pareado com presença de ovissacos, condição simplesiomórfica semelhante à de outras famílias de Polydesmida.
Subject(s)
Animals , Arthropods/anatomy & histology , Genitalia, Female , Ovary/anatomy & histology , ReproductionABSTRACT
Polydesmida is the largest order in the class Diplopoda in terms of the number of species, genera and families, but there are few studies of the ovarian morphology of species in this order. This study aimed to perform a comparative study of the ovarian morphology of three species from this order to increase the understanding of the morphological evolution of this system in Polydesmida. Adults females of two of these species, Poratia salvator and Myrmecodesmus hastatus, belonging to the family Pyrgodesmidae, had a unpaired ovary that formed a tubular organ containing oocytes, with P. salvator present grouping of oocytes into a structure similar to ovisacs. This condition appeared to be apomorphic and was associated with the small size of these species (< 10 mm) and their short life cycle. The third species, Telonychopus klossae (Chelodesmidae), had a large body and an ovary with paired ovisacs, which was symplesiomorphic with other Polydesmida families.
Subject(s)
Arthropods/anatomy & histology , Arthropods/classification , Ovary/anatomy & histology , Animals , Female , Species SpecificityABSTRACT
Diplopods are very susceptible to various degrees of environmental disturbance, particularly climate, altitude and diet. In order to increase our understanding of millipede ecological plasticity, we used fertility tables to access and to compare the fertility and survival of two populations of the parthenogenetic species Poratia salvator from two areas with distinct characteristics. Collecting was conducted in two localities within the state of Mato Grosso, in the Pantanal of Mato Grosso, municipality of Nossa Senhora do Livramento, and in the municipality of Várzea Grande. The specimens were maintained at room temperature. In the first generation, individuals from the Pantanal of Mato Grosso population reproduced early and also died earlier when compared with individuals from the Várzea Grande population. Furthermore, the population from the Pantanal had a lower net reproduction rate and a higher intrinsic growth rate than the population from the Várzea Grande. The generation time was lower for the Pantanal population than for the Várzea Grande population. In the second generation, the net reproduction rate observed for both populations was higher than that observed in the first generation, suggesting an increase in the reproductive potential of the females throughout their lives. The intrinsic growth rate of both populations decreased as a function of an increase in generation time observed in the second generation. As a result, the population growth rate in the second generation was slower when compared with the first generation, probably a result of the longer life expectancy of the second generation, which may have become adapted to the artificial conditions of the experiment.
