Reproduction of <i>Balea</i> (<i>Pseudalinda</i>) <i>fallax</i> (Rossmässler, 1836) (Gastropoda: Pulmonata: Clausiliidae) kept under laboratory conditions

Abstract

Balea fallax (Rossm.) collected from the Roztocze Upland (SE. Poland) was kept in the laboratory for four years. Observations were conducted between March and October when the snails were kept at room temperature (18-25°C); in winter they were stored at 3°C. The egg-laying period started in late March and lasted till October, with maxima in spring and early autumn. The snails laid oval, gelatinous eggs with separate calcium carbonate crystals in the external envelope (average egg size 1.96 × 1.73 mm). The eggs were deposited in batches (up to 14 eggs at a time) or singly. The number of batches per snail per year ranged between 1 and 4. Snails isolated before maturation laid defective eggs which failed to develop, which suggest that the species is incapable of uniparental reproduction or at least the ability is very limited. The reproduction rate decreased during consecutive years, probably as a result of the aging or the shortage of allosperm in isolated individuals. Compared to batches of typically oviparous clausiliids, eggs of B. fallax hatched slightly earlier (interval between oviposition and hatching lasted 8-10 days at room temperature). It is likely that the adults retained developing eggs in the uterus for a short time. The juveniles needed at least 6 months to attain the ultimate shell size.

Selfing and brooding in Alinda biplicata (Gastropoda: Pulmonata: Clausiliidae) – life history traits of a good coloniser

“…A similar phenomenon has been observed in Balea fallaxan egg-retainer (Sulikowska-Drozd & Maltz, 2012). The eggs laid by A. biplicata are oval, slightly elongated, of a size similar to the eggs of oviparous clausiliids of smaller shell size and much smaller than the eggs laid by egg-retaining clausiliids of similar shell size (see Maltz & Sulikowska-Drozd, 2008;Sulikowska-Drozd, 2009;Sulikowska-Drozd & Maltz, 2012). Egg-laying by A. biplicata should be regarded as an anomaly which indicates some developmental disturbances during early embryogenesis which may be a form of self-fertilisation depression.…”

“…Egg-laying by A. biplicata should be regarded as an anomaly which indicates some developmental disturbances during early embryogenesis which may be a form of self-fertilisation depression. The eggs are produced exclusively by uniparentally reproducing snails; never by snails kept in pairs at constant temperature and humidity (Maltz & Sulikowska-Drozd, 2012). It should be emphasised that only 16% of the isolated snails produced exclusively eggs and consequently failed to reproduce.…”

“…In A. biplicata the typical reproduction of snails kept in pairs and groups is giving birth to neonates (live-bearing reproduction), and the embryonic development takes place in eggs retained in the parent's body (Maltz & Sulikowska-Drozd, 2012), which places it in the group of brooders or viviparous snails.…”

“…Tbe material included snails from tbe laboratory culture wbicb was started in October 2004 (initial material was collected at two sites in soutbem Poland -10 adults from eacb) (Maltz & Sulikowska-Drozd, 2012), bom in August and September 2007 and isolated in October and November 2007 as sexually immature juveniles (stage of 6-7 wborls) (N = 30) (see Maltz & Sulikowska-Drozd, 2008,2011. Tbe snails were randomly selected from among litters of various parents (12 pairs bom in culture as a part of offspring of tbe initial material), witb known birtb date.…”

“…-major diameter (mm) -minor diameter ( production) and more fecund (Maltz & Sulikowska-Drozd, 2012). According to Escobar et al (2011), there are several parameters of the mating system that can provide information about the typical form of fertilisation for a hermaphroditic species (selfing/intermediate/outcrossing): selfing rate (S -derived from molecular markers), waiting time (WT), mean age at first reproduction of isolated individuals (75), mean age at first reproduction of cross-fertilised specimens (To), mean juvenile survival (W: W5 -for offspring from obligate self-fertilisation.…”