Parthenogenesis, polyploidy and reproductive seasonality in the Taiwanese mountain earthworm Amynthas catenus Tsai et al., 2001 (Oligochaeta, Megascolecidae)
Journal
Pedobiologia
Journal Volume
54
Journal Issue
2
Pages
133-139
Date Issued
2011
Author(s)
Abstract
Amynthas catenus Tsai et al., 2001 is a terrestrial earthworm belonging to the Pheretima complex of the family Megascolecidae. It is endemic to Mt. Hohuan of central Taiwan at elevations of 2985-3004 m. Its reproductive organs showed various stages of degeneration in the present study. The spermathecae varied from being absent (athecal) to three pairs in VI-VIII (sexthecal), and the prostate glands from a large, symmetrical pair to complete absence. For the 44 specimens examined from May 2008 to May 2010, there were 47.7% athecals, 36.4% sexthecals and 15.9% intermediates. Results of a flow cytometric analysis showed that there were three DNA ploidy levels - diploid, triploid and tetraploid (2. n, 3. n, and 4. n) - for the athecals but only diploid for the sexthecals. The intermediates consisted of diploids and triploids. The diploids had 2. n=112 and the triploids 3. n=168. The haploid chromosome number of A. catenus was 56. Spermatogenesis occurred throughout the year with the highest activity in summer for both athecals and sexthecals, but the number of mature ova peaked in summer for the athecals and in spring for the sexthecals. There was no significant difference in mean number of mature ova produced between the athecals and the sexthecals, but the sexthecals had significantly higher spermatogenetic activity than the athecals. For all specimens examined, sperm were present in testes and seminal vesicles but not in spermathecae, an indication of parthenogenesis in the species. © 2011 Elsevier GmbH.
Subjects
Amynthas catenus; Earthworm; Flow cytometry; Parthenogenesis; Polyploidy; Reproductive seasonality
Other Subjects
breeding season; chromosome; earthworm; endemic species; flow cytometry; parthenogenesis; polyploidy; reproductive biology; seasonality; secondary sexual characteristics; taxonomy; type specimen; Amynthas; Annelida; Megascolecidae; Oligochaeta (Metazoa); Pheretima
Type
journal article