The scleractinian Agaricia undata as a new host for the coral-gall crab Opecarcinus hypostegus at Bonaire, southern Caribbean

Jaaziel E García-Hernández,Werner De Gier,Bert W Hoeksema,Godfried W N M Van Moorsel

doi:10.1007/s13199-020-00706-8

Abstract

The Caribbean scleractinian reef coral Agaricia undata (Agariciidae) is recorded for the first time as a host of the coral-gall crab Opecarcinus hypostegus (Cryptochiridae). The identity of the crab was confirmed with the help of DNA barcoding. The association has been documented with photographs taken in situ at 25 m depth and in the laboratory. The predominantly mesophotic depth range of the host species suggests this association to be present also at greater depths. With this record, all seven Agaricia species are now listed as gall-crab hosts, together with the agariciid Helioseris cucullata. Within the phylogeny of Agariciidae, Helioseris is not closely related to Agaricia. Therefore, the association between Caribbean agariciids and their gall-crab symbionts may either have originated early in their shared evolutionary history or later as a result of host range expansion. New information on coral-associated fauna, such as what is presented here, leads to a better insight on the diversity, evolution, and ecology of coral reef biota, particularly in the Caribbean, where cryptochirids have rarely been studied.

Highlights

Reef coral species of various scleractinian families are known to host coral-gall crabs of the brachyuran family Cryptochiridae
During a marine biodiversity survey at Bonaire (22 October – 9 November 2019), Caribbean Netherlands, we studied the occurrence of corals and associated fauna at 35 stations using the roving diver technique (Hoeksema and Koh 2009)
The dwellings were typical for Opecarcinus hypostegus as encountered in various Agaricia spp. hosts (Kropp 1989; van der Meij et al 2015; van Tienderen and van der Meij 2017; van Moorsel and van der Meij 2018)

Summary

Introduction

Reef coral species of various scleractinian families are known to host coral-gall crabs of the brachyuran family Cryptochiridae. These crabs dwell inside pits or galls inside the coral skeleton (Castro 1976, 2015; Klompmaker et al 2016; Chan et al 2020). With over 1600 scleractinian species on record (Hoeksema and Cairns 2020a), it is far from clear which coral taxa host gall crabs This information would help to clarify which coral species are inhabited by cryptochirds and which ones are not, and whether such presence-absence patterns have the same evolutionary origin. Since some closely related coral species have different bathymetric ranges (Hoeksema 2012; Bongaerts et al 2013; Muir et al 2015; Roberts et al 2019), the presence-absence of crab inhabitation may depend on particular depth limits of their hosts, like for Christmas tree worms

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