Archachatina churchilliana (Melvill & Ponsonby, 1895)

Sirgel, W. F., 2004, A further note on Archachatina churchilliana and a description of the genital anatomy of Archachatina natalensis (Mollusca: Pulmonata: Achatinidae), African Invertebrates 45, pp. 271-278 : 272-273

Archachatina churchilliana (Melvill & Ponsonby, 1895)

Observations: The above­mentioned individual of Archachatina churchilliana with a uniformly pale yellow shell, bred from flammulate parents and grandparents, attained 7.5 whorls and a length of 68.5 mm at the age of one year ( Fig. 1 ). Other similar­sized pale yellow specimens, on dissection, presented a fully developed genital system ( Sirgel 2000) and it seemed logical to assume that this captive­bred individual was more or less fully grown at that time, as no other specimens of this morph with a significantly larger shell have been recorded. The specimen was nonetheless kept in the laboratory for a further two years (to February 2004) at which stage it died. During its second year of life it added another 1.5 whorls to the shell, to reach nine whorls with a total length of 93.5 mm and a diameter of 36 mm, with the last whorl measuring 56 mm. The result of this added growth was a shell with a size and shape ( Fig. 2 ) significantly different from that in the original description of A. churchilliana . Shell size at one year ( Fig. 3) is more or less equal to that given for A. natalensis by Connolly (1939), and they will be compared towards the end of this paper.

Remarks: It is thus clear that, at least under controlled conditions, individuals of A. churchilliana with pale yellow shells are capable of growing to the same size as the flammulate ones. This poses the question as to why such apparently fully grown specimens have never been collected in the field, considering that absence of flammulation is clearly not a trait linked to smaller size. There may be a number of explanations, but one possibility could be that the non­flammulate shells are less camouflaged in their natural habitat than their flammulate counterparts and are thus taken by predators before they become fully grown.

Figures

Figs 1, 2. Archachatina churchilliana. The same specimen at the age of one year (Fig. 1, length 68.5 mm) and three years (Fig. 2, length 93.5 mm).