Vol. 59, 2020
(update: 2020.02.15; 03.12)
Sexual Dimorphism and Reproductive Status of the Red Swamp Crayfish Procambarus clarkii
Katsuyuki Hamasaki*, Naoko Osabe, Sota Nishimoto, Shigeki Dan, and Shuichi Kitada
of Marine Biosciences, Tokyo University of Marine Science and
Technology, Konan, Minato, Tokyo 108-8477, Japan. *Correspondence:
Received 15 December 2018 / Accepted
12 February 2020
red swamp crayfish Procambarus
clarkii is native to northeastern Mexico and the south-central
USA, and it has expanded its distribution worldwide and negatively
impacted the ecosystems in the invaded regions. The dynamics of the P. clarkii populations have been
studied as the basis for the development of effective control measures
against this invasive alien species. Adult males of P. clarkii exhibit a cyclical
dimorphism between two sexual morphotypes; reproductive form I has
large chelae and non-reproductive form II has small chelae. However,
whether P. clarkii females
have two sexual morphotypes and exhibit form alternation has not been
resolved, and little is known about the degree of intra-sexual
dimorphism of the chelae, even among males. We employed allometric
growth analysis on the chelae dimensions of P. clarkii females and males that
were collected from a small pond in Yokohama, Japan. Our analysis
demonstrated the existence of form I, which has larger chelae, and form
II, which has smaller chelae, in P.
clarkii females and highlighted the intra- and inter-sexual
dimorphisms in the chelae of this species. The reproductive cycle of
the population was successfully traced by the reproductive status of P. clarkii based on the
occurrence patterns of each sexual morphotype; the form I crayfish
occurred throughout the sampling period from April to December, while
the occurrences of form I females and males were highly correlated,
peaking in October. Our results suggested that alternation of sexual
forms occurs in P. clarkii females.
The ability to discriminate between the sexual morphotypes based on
chelae allometric growth would allow us to evaluate the female
reproductive status more easily ansd precisely in invasive P. clarkii populations.
Key words: Form alternation, Reproductive ecology, Allometric growth, Sexual maturity, Invasive alien species.
Hamasaki K, Osabe N, Nishimoto S, Dan S, Kitada S. 2020. Sexual
dimorphism and reproductive status of the red swamp crayfish Procambarus clarkia. Zool Stud 59:07. doi:10.6620/ZS.2020.59-07.