Maturation timing in the land snailsArchachatina marginata ovum(Pfeiffer) andLimicolaria flammea(Müller) (Pulmonata: Achatinidae)

Gross anatomy and characteristics of the reproductive system of the land snail Archachatina marginata ovum (Pfeiffer) during the breeding season

“…The reproductive season of A. marginata ovum coincides with their period of greatest activity: egg-laying occurs between April and August. More eggs are produced by the snails near the beginning of the rainy season and fewer eggs towards the end (Egonmwan 2004). Snail collection is more intense during the rainy season (Cobbinah and Osei-Nkrumah 1988) than in the dry season, when the snails hide in undergrowth, which creates a microclimate that ensures their survival but makes it diffi cult for collectors to locate them.…”

“…The snails obtained from the snail hunters and examined during this study were, unsurprisingly, mainly adults. In natural fi eld conditions and in laboratory cultures, a wide variation in the reproductive stages has been reported for A. marginata ovum, due to the coexistence of up to four year-classes (Plummer 1975;Egonmwan 2004). This variation may also be due to the fact that hatchlings of snails from the same egg clutch grow at different rates, whether in the fi eld or in controlled laboratory rearing (Emberton 1985).…”

“…The subspecies A. marginata ovum (Pfeiffer) is differentiated by the apricot-yellow colour of its columella, parietal wall and summit of the spire. The breeding season of A. marginata ovum is from March/May to October to coincide with the rainy season, which starts in March and ends in October (Egonmwan 2004) with a peak in June.…”

“…Although some aspects of the biology of A. marginata ovum have been studied (Plummer 1975(Plummer , 1982Ajayi et al 1978;Egonmwan 2004), the gross anatomy and characteristics of the reproductive organs during the breeding season, in a natural population from the wild, have not yet been reported. In recent years more attention has been paid to the commercial farming of achatinid land snails in many West African countries, as opposed to the hunting of natural populations which have been greatly depleted by deforestation, bush-burning and overexploitation (Ajayi et al 1978).…”

Light and electron microscopy study of late embryonic development in the land snail Limicolaria flammea (Müller) (Pulmonata, Achatinidae)

“…Molluscan eggs vary from simple zygotes with only primary or vitelline membrane to large ones, with several protective membranes and a nutrient store which in terrestrial gastropods allow the provision of a specialized environment for the development of the embryo which consumes a different food resource to the adults (RUNHAM 1994). The eggs of L. flammea have hard calcareous shells and each egg constitutes 0.65% of the body weight of the adult snail (EGONMWAN 2004). Large eggs have large nutritive stores within the zygote and are packed in a variety of nutritive and protective layers (RUNHAM 1994).…”