Reproduction of <i>Omalonyx matheroni</i> (Gastropoda: Succineidae) under laboratory conditions

Abstract

Abstract:The life histories of succineids have received relatively little attention. To evaluate life history characteristics of Omalonyx matheroni, we studied a Brazilian population (Reserva Particular do Patrimônio Natural Feliciano Miguel Abdala, in Caratinga, Minas Gerais, Brazil) under laboratory conditions. The aims of the present study were (1) to describe in detail an appropriate rearing method; (2) to investigate the effects of different temperature and photoperiod conditions; and (3) to assess the effects of self and cross-fertilization on the reproductive biology of these mollusks. We studied the oviposition site, the time to sexual maturity and the influences of photoperiod and temperature on reproductive parameters of O. matheroni reared under laboratory conditions. We tested three combinations of temperature and photoperiod, designated A, B and C (A: 25ºC, 24 hours of light; B: environmental conditions of temperature and photoperiod, characterized as follows: average maximum temperature=27.1ºC, average minimum temperature=18.3ºC, average day length=12.06 hours; and C: 25ºC, zero hours of light) and two rearing densities (I: isolated and G: grouped) on reproductive parameters (number of eggs per egg mass, number of unviable eggs per mass, egg mass incubation period, and duration of the hatching period). A total of 186 individuals and 565 egg masses were studied. Data were analyzed by Student's t-test, two-way ANOVA and Chi-Square test. Eight generations were produced (March/2004-March/2006), from 35 field specimens, 91% of 3 197 eggs hatched. The time to sexual maturity was approximately three months for individuals reared in groups or in isolation (Student's t-test: t=1.41, df=31, p=0.16); however, they differed significantly in weight (Student's t-test: t=3.6, df=31, p<0.001). Regarding the influences of temperature and photoperiod on reproductive parameters, under natural environmental conditions, individuals produced a greater number of eggs per mass (ANOVA: F 2,573 =84.15, p<0.001), with a longer incubation period (ANOVA: F 2;559 =170.05, p<0.001). The extreme photoperiod conditions of 24 hours of light or zero hours of light likely imposed stress and could be related to the significant reductions in the number of eggs per mass, and egg incubation period as well as the increased synchrony in egg hatching. No correlations were observed between the number of unviable eggs per mass and the temperature, photoperiod (ANOVA: F 2,573 =0.87, p=0.92) or rearing density (ANOVA: F 1,573 =0.21, p=0.64). Individuals reared in isolation under natural conditions produced more eggs per mass and did not presented any disadvantage with respect to the variables analyzed as compared to the animals reared in groups. These results indicate that O. matheroni can successfully reproduce by selfing. Rev. Biol. Trop. 60 (2): 553-566. Epub 2012 June 01.

Integrative taxonomy of the neotropical genus Omalonyx (Elasmognatha: Succineidae)

“…All samples were obtained through surveys of freshwater, swamps or river and lakeshore vegetation. Most sampling localities yielded adults; however, in Kaw (French Guiana) and Belém (Pará, Brazil), only egg clutches were found and they were reared to sexual maturity according to Montresor, Teixeira, Paglia and Vidigal (). Voucher material was deposited in the Malacological Collection of the Laboratório de Malacologia e Sistemática Molecular, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais (LMSM).…”

Demography of the land snail Tikoconus (Tikoconus) costarricanus (Stylommatophora: Euconulidae) in tropical low montane and premontane forests, Costa Rica

“…Incubation time of T. (T.) costaricanus is a little long compared to other neotropical species: Polymita muscarum (10 days) (Bidart, Fernández, & Iglesias, 1998), Polymita venusta (8 days) (Bidart et al, 1998), O. fulgens (14 days) (Barrientos, 1998) and Succinea costaricana (11 days) (Villalobos et al, 1995). This can be a specific species characteristic or a result of different environmental temperatures (Montresor, Teixeira, Paglia, & Vidiga, 2012): T. (T.) costaricanus' habitat is colder than the habitats of the other species for which there are reports.…”

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

“…Biparental reproduction is very common among Gastropoda, while uniparental reproduction is still poorly known: it has been recorded for representatives of 14 genera of Prosobranchia (parthenogenesis), 3 genera of Opisthobranchia (selfing), and about 40 genera of Pulmonata (selfing) (Lucarz, 1991;Heller, 1993-literature review, Chen, 1994Bessa & Aratjjo, 1995;Wirth et al, 1997;Almeida & Bessa, 2001;Silva et al, 2008Silva et al, , 2009Carvalho et al, 2009;Escobar et al, 2011;Montresor et al, 2012). Among Clausiliidae it has only been recorded for Balea perversa (Wirth et al, 1997;Baur & Baur, 2000).…”