Extreme secondary sexual dimorphism in the genus Florarctus (Heterotardigrada: Halechiniscidae)
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Extreme secondary sexual dimorphism in the genus Florarctus (Heterotardigrada : Halechiniscidae). / Gasiorek, Piotr; Kristensen, David Mobjerg; Kristensen, Reinhardt Mobjerg.
In: Marine Biodiversity, Vol. 51, No. 3, 52, 2021.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Extreme secondary sexual dimorphism in the genus Florarctus (Heterotardigrada
T2 - Halechiniscidae)
AU - Gasiorek, Piotr
AU - Kristensen, David Mobjerg
AU - Kristensen, Reinhardt Mobjerg
PY - 2021
Y1 - 2021
N2 - Secondary sexual dimorphism in florarctin tardigrades is a well-known phenomenon. Males are usually smaller than females, and primary clavae are relatively longer in the former. A new species Florarctus bellahelenae, collected from subtidal coralline sand just behind the reef fringe of Long Island, Chesterfield Reefs (Pacific Ocean), exhibits extreme secondary dimorphism. Males have developed primary clavae that are much thicker and three times longer than those present in females. Furthermore, the male primary clavae have an accordion-like outer structure, whereas primary clavae are smooth in females. Other species of Florarctus Delamare-Deboutteville & Renaud-Mornant, 1965 inhabiting the Pacific Ocean were investigated. Males are typically smaller than females, but males of Florarctus heimi Delamare-Deboutteville & Renaud-Mornant, 1965 and females of Florarctus cervinus Renaud-Mornant, 1987 have never been recorded. The Renaud-Mornant collection was re-examined, and type series were analysed. Florarctus heimi and F. cervinus were always found together in the coralline sand of Heron Island (Great Barrier Reef). The animals were kept alive and surveyed in the laboratory of the Queensland Museum. All studied individuals of the larger F. heimi (up to ca. 400 mu m) were females, and all adults of the smaller F. cervinus (about 170 mu m) were males. Males of F. cervinus were observed mating with females of F. heimi. Following those morphological and behavioural lines of evidence, we propose that F. cervinus is a junior synonym of F. heimi. Based on the discovery of dimorphism in F. bellahelenae sp. nov. and the strong sex-related morphological disparities in F. heimi, we suggest that extreme secondary dimorphism may be present in other florarctin arthrotardigrades.
AB - Secondary sexual dimorphism in florarctin tardigrades is a well-known phenomenon. Males are usually smaller than females, and primary clavae are relatively longer in the former. A new species Florarctus bellahelenae, collected from subtidal coralline sand just behind the reef fringe of Long Island, Chesterfield Reefs (Pacific Ocean), exhibits extreme secondary dimorphism. Males have developed primary clavae that are much thicker and three times longer than those present in females. Furthermore, the male primary clavae have an accordion-like outer structure, whereas primary clavae are smooth in females. Other species of Florarctus Delamare-Deboutteville & Renaud-Mornant, 1965 inhabiting the Pacific Ocean were investigated. Males are typically smaller than females, but males of Florarctus heimi Delamare-Deboutteville & Renaud-Mornant, 1965 and females of Florarctus cervinus Renaud-Mornant, 1987 have never been recorded. The Renaud-Mornant collection was re-examined, and type series were analysed. Florarctus heimi and F. cervinus were always found together in the coralline sand of Heron Island (Great Barrier Reef). The animals were kept alive and surveyed in the laboratory of the Queensland Museum. All studied individuals of the larger F. heimi (up to ca. 400 mu m) were females, and all adults of the smaller F. cervinus (about 170 mu m) were males. Males of F. cervinus were observed mating with females of F. heimi. Following those morphological and behavioural lines of evidence, we propose that F. cervinus is a junior synonym of F. heimi. Based on the discovery of dimorphism in F. bellahelenae sp. nov. and the strong sex-related morphological disparities in F. heimi, we suggest that extreme secondary dimorphism may be present in other florarctin arthrotardigrades.
KW - Clavae
KW - Fertilisation
KW - Mating behaviour
KW - Meiofauna
KW - Tardigrades
KW - MATING-BEHAVIOR
KW - REPRODUCTIVE-SYSTEM
KW - MARINE TARDIGRADES
KW - GENITAL ORGANS
KW - PARENTAL CARE
KW - N-SP
KW - ARTHROTARDIGRADA
KW - BIOLOGY
KW - ULTRASTRUCTURE
KW - BIODIVERSITY
U2 - 10.1007/s12526-021-01183-y
DO - 10.1007/s12526-021-01183-y
M3 - Journal article
VL - 51
JO - Marine Biodiversity
JF - Marine Biodiversity
SN - 1867-1616
IS - 3
M1 - 52
ER -
ID: 272405209