Tauphaedusa sheridani (Pfeiffer, 1866)

Sulikowska-Drozd, Anna, Hirano, Takahiro, Wu, Shu-Ping & Páll-Gergely, Barna, 2018, High Fecundity, Rapid Development and Selfing Ability in Three Species of Viviparous Land Snails Phaedusinae (Gastropoda: Stylommatophora: Clausiliidae) from East Asia, Zoological Studies 57 (38), pp. 1-11 : 3

Tauphaedusa sheridani

( Fig. 1 )

The F0 individuals (n = 8) placed in the culture were on average 16.55 mm high (SD = 0.72) and consisted of 9.9 whorls (SD = 0.3). They released offspring repeatedly during the experiment (total 741 neonates). During a year, they produced 115 to 195 neonates per pair of snails (mean 164.5, SD = 34.4, n = 4). During a week, the pairs delivered 3.5-4.8 neonates on average (median 4.7, n = 4). On delivery, the neonates had shells 2.00- 2.73 mm high (mean 2.3 mm, SD = 0.15, n = 31) with 2.5 whorls ( Fig. 1B ). Time needed for shell growth ranged between 88 and 113 days (n = 10). The first reproduction of F1 generation was recorded 160 days after birth.

The fecundity of the F1 generation was recorded for 18 snails kept in pairs. During a year, they produced between 109 and 226 neonates per pair of snails (mean 166, SD = 36.8, n = 9). During a week, an average of 3-6.5 neonates were delivered per pair of snails (median 5, n = 9). Also, virgin T. sheridani were capable of reproduction (100% out of 8 individuals). They started releasing neonates seven month after birth and continued until the end of the experiment. During a year, between 65 and 90 neonates were released per virgin snail (mean 77.4, SD = 9.1, n = 8) and during a week, between 1 and 6 (median 2, n = 8).

Tauphaedusa sheridani , kept under high humidity, contained 4 to 9 eggs and embryos in the reproductive tract (mean 6.8, SD = 1.37, n = 15) ( Fig. 1D, E ). The majority of the retained offspring (49%) were at the first stage of development (without shelled embryo). Embryos advanced in development (stage IV) were found in low numbers in every adult (range 1-4, mean 2.2, SD = 0.8, n = 15). The embryos’ stage IV shell height varied from 1.48 to 2.47 mm (mean 2.02 mm, SD = 0.25, n = 33) and number of whorls from 1.5 to 3 (mean 2.25, SD = 0.5, n = 33).

No adult T. sheridani died during the 60- day exposure to drought. In snails dissected immediately after the experiment, the mean number of eggs and embryos was 5.4 (SD = 1.4, range 3-9, n = 27). The majority of embryos (80%) were advanced in development (stage IV). The shell height of embryos varied from 1.4 to 2.4 mm (mean 2.10 mm, SD = 0.20, n = 113) and number of whorls from 2.0 to 3.0 (mean 2.5, SD = 0.22, n = 113).

Figures

Fig. 1. Tauphaedusa sheridani. (A) adults (F1 generation); (B) neonates; (C) clausilia; (D-E) - eggs and embryos from dissected adults. Scale bar = 1 mm. © 2018 Academia Sinica, Taiwan