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Vol. 61, 2022
(update: 2022.12.26)
New Insights into the Male
Morphotypes of the Amphidromous Shrimp Macrobrachium olfersii (Weigmann,
1836) (Caridea: Palaemonidae) and a Discussion on Social Dominance
Hierarchies
Rafael Carvalho Santos1,* , Caio
Santos Nogueira1, Milena
Silva Jaconis1, Thiago
Maia Davanso1, Rogerio
Caetano Costa1, and Gustavo Luis Hirose2
doi:10.6620/ZS.2022.61-83
1Laboratory
of Biology of Marine and Freshwater Shrimps (LABCAM), Department of
Biological Sciences, Faculty of Sciences, São Paulo State University
(UNESP), Bauru, São Paulo, Brazil. *Correspondence: E-mail:
rafa_bio@hotmail.com.br (Santos)
E-mail: caiosnogueira@hotmail.com (Nogueira); mi.jaconis@gmail.com
(Jaconis); tdavanso@hotmail.com (Davanso); rogerio.c.costa@unesp.br
(Costa)
2Laboratory of Carcinology, Department of
Biology, Federal University of Sergipe (UFS), São Cristóvão, Sergipe,
Brazil. E-mail: gustavo_lh@hotmail.com (Hirose)
Received 30 April 2022 / Accepted 7
October 2022
Communicated by Benny K.K. Chan
Male
morphotypes in a population may lead to the development of social
dominance hierarchies in crustacean species. Currently, Macrobrachium is the decapod
crustacean genus with the largest record of species that present the
development of hierarchies. Macrobrachium
olfersii
has morphological characteristics that indicate the presence of male
social dominance within its populations. Thus, the present study tested
the hypothesis of the occurrence of male morphotypes in M. olfersii
through morphometric and morphological analysis of the chelipeds.
Sampling was carried out from March 2018 to October 2021 in seven
points along the Jequitinhonha River, Northeast Brazil. A total of 264
males were collected with carapace length (CL) ranging from 4.01 to
23.70 mm. Morphological sexual maturity size was estimated at 8.95 mm
CL. The morphometric and morphological analysis confirmed the presence
of three adult male morphotypes: M1, M2, and M3. The characterization
of the different morphotypes was mainly due to the variation in size,
shape, and morphology of the largest cheliped of the second pair of
pereopods. Most morphometric relationships differed significantly (p
< 0.01) among the three morphotypes, mainly between M3 against M1
and M2. The variation in the propodus shape was also evident. This
trait and the angulation of the spines differed significantly
between morphotypes (p <
0.01), with the propodus of morphotype M3 being more robust and
carrying a greater number of spines than the others. The occurrence of
social dominance and the exaggerated development of a cheliped (weapon)
can be advantageous for dominant individuals when they need to compete
for resources. This morphological trait can provide these individuals
with advantages during fights and guarantee access to the best
resources, whether they are shelter, food, or sexual partners. Our
results add new information to the biology of M. olfersii, as well as the
genus Macrobrachium,
and the occurrence of social dominance in species of this group. In
addition, by describing these morphotypes in detail, using a set of
complementary morphological and morphometric techniques, it is possible
to access the differential morphology along the M. olfersii males, as well as
confirm a life history trait found in several Macrobrachium species.
Key words: Allometry,
Chelipeds, Geometric morphometrics, Relative growth, Decapoda.
Citation:
Santos RC, Nogueira CS, Jaconis MS, Davanso TM, Costa RC, Hirose G.
year. New insights into the male morphotypes of the amphidromous shrimp
Macrobrachium olfersii
(Wiegmann, 1836) (Caridea: Palaemonidae) and a discussion on social
dominance hierarchies. Zool Stud 61:83. doi:10.6620/ZS.2022.61-83.
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