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The Crustacean Society Morphology and reproduction in the Hapalocarcinus marsupialis Stimpson, 1859 species complex (Decapoda: Brachyura: Cryptochiridae)

Bähr, Susanne; Johnson, Magnus L; Berumen, Michael L; Hardenstine, Royale S; Rich, Walter A; Van Der Meij, Sancia E T


Susanne Bähr

Michael L Berumen

Royale S Hardenstine

Walter A Rich

Sancia E T Van Der Meij


Symbiotic relationships contribute considerably to the high biodiversity found on coral reefs. Coral-dwelling gall crabs (Cryptochiridae) represent a prime example of coral-associated invertebrates that exhibit obligate relationships with their host. The induction of a skeletal modification in the coral, used as a dwelling by the crab, is the most remarkable aspect of this close association. Here we examined Hapalocarcinus marsupialis Stimpson, 1859, collected from Pocillopora and Stylophora corals in the Saudi Arabian Red Sea. Specimens were DNA barcoded, and five distinct clades were revealed, providing further evidence for the hypothesis that H. marsupialis is a species complex. Divergence (COI) between the clades ranged from 3.2 to 15.7%. The putative species were tested for differences in morphology and reproduction. Crabs were examined regarding morphometric characters (carapace length and width, pleon (abdomen), chelae, and growth patterns) and reproductive traits. The data were pooled and analysed by host genus and putative species, which revealed significant differences for most of the measured variables in female crabs. Specimens retrieved from Pocillopora were significantly larger (up to 49 %) and had higher fecundity than those inhabiting Stylophora. For reproductive output (RO) no differences at species-or host-genus level were detected. The average RO of ~70% over all specimens is high compared to other brachyurans, supporting the assumption that symbiotic brachyurans invest more energy in reproduction than their free-living counterparts. Discrepancies with published data on growth and reproduction of Hapalocarcinus are discussed. Our results demonstrate the usefulness of morphometric traits and fecundity in separating the clades in the H. marsupialis complex, and prepare the ground for further morpho-metric studies on the genus and other symbiotic brachyurans. Moreover, it highlights the need to check for the presence of cryptic species when studying aspects of the biology of a species.


Bähr, S., Johnson, M. L., Berumen, M. L., Hardenstine, R. S., Rich, W. A., & Van Der Meij, S. E. T. (2021). The Crustacean Society Morphology and reproduction in the Hapalocarcinus marsupialis Stimpson, 1859 species complex (Decapoda: Brachyura: Cryptochiridae). Journal of Crustacean Biology, 41(3), Article ruab052.

Journal Article Type Article
Acceptance Date Sep 7, 2021
Online Publication Date Sep 30, 2021
Publication Date Sep 1, 2021
Deposit Date Nov 1, 2023
Publicly Available Date Nov 2, 2023
Journal Journal of crustacean biology
Print ISSN 0278-0372
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 41
Issue 3
Article Number ruab052
Keywords Associated coral fauna; Cryptic species; Crustacea; Gall crabs; Genetic fingerprinting; Host specificity; Pocilloporidae; Scleractinian corals; Symbiosis
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© The Author(s) 2021. Published by Oxford University Press on behalf of The Crustacean Society. All rights reserved. For permissions, please e-mail: This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.

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