Tauphaedusa tau (O. Boettger, 1877)

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 tau

( Fig. 2 )

The F0 individuals placed in the culture released offspring repeatedly during the experiment (total 2,630 neonates). During a year, they produced between 101 and 237 neonates per pair of snails (mean 168.7, SD = 39.8, n = 11). During a week, pairs delivered 2.0-5.2 neonates (median 3.8, n = 14). At the moment of release, the neonates had shells 1.5-2.25 mm high (mean 1.90 mm, SD = 0.18, n = 30) with 2.0-2.5 whorls ( Fig. 2B ). For the first group of juveniles, the period of shell growth lasted 78-99 days (n = 7). The first reproduction was recorded 132 days from birth. The second group of juveniles attained the ultimate shell size after 88 - 117 days (n = 11). The first reproduction was recorded 162 days from birth. Measured adult F0 individuals were on average 14.12 mm high (SD = 0.57, n = 18) and consisted of 9.7 whorls (SD = 0.3, n = 18).

In the laboratory, virgin T. tau were capable of reproduction (100% out of 9 individuals). They started producing neonates eight month after birth and continued until the end of the experiment. During a year, between 2 and 60 neonates were released per virgin snail (mean 30.44, SD = 15.03, n = 9). During a week, between 1 and 6 offspring were delivered (median 2, n = 9).

Tauphaedusa tau (F1 generation), kept under high humidity, contained 3 to 11 eggs and embryos in the reproductive tract (mean 7.06, SD = 2.66, n = 17) ( Fig. 2D, E ). The majority of the retained offspring (44%) were at the first stage of development (without shelled embryo). Embryos advanced in development (stage IV) were found in most snails (mean number 1.9, SD = 1.5, n = 17). The embryos’ shell height varied from 1.2 to 2.2 (mean 1.74 mm, SD = 0.24, n = 33) and number of whorls from 1.5 to 2.75 (mean 2.2, SD = 0.38, n = 33). No adult T. tau died during the exposure to 60 days of drought. In snails dissected immediately after the experiment, the mean number of eggs and embryos was 3.30 (SD = 2.07, range 0-9, n = 27). The majority of embryos (65%) were advanced in development (stage IV). The shell height of embryos varied from 1.0 to 2.1 mm (mean 1.70 mm, SD = 0.20, n = 50) and number of whorls from 1.25 to 2.75 (mean 2.2, SD = 0.36, n = 50).

Figures

Fig. 2. Tauphaedusa tau. (A) adult (F1 generation); (B) neonates; (C) clausilia; (D-E) eggs and embryos from dissected adults. Scale bar = 1 mm. © 2018 Academia Sinica, Taiwan