2016 Rosenstiel School of Marine & Atmospheric Science of the University of Miami ... 3 Smithsonian Marine Station at Fort Pierce, Fort Pierce, Florida 34949. * Corresponding ... murinae, respectively (See Online Appendix 1). Information on ...
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BULLETIN OF 92(1):000–000. MARINE SCIENCE. 00(0):000–000. 0000 Bull Mar Sci. 2016 doi:10.5343/ http://dx.doi.org/10.5343/bms.2015.1063
New records and field observations support a facultative commensal association of Thalamita longifrons and Thalamita murinae with soft coral Nathaniel Evans 1, 2 *, C Seabird McKeon 2, 3 Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611. National Museum of Natural History, Smithsonian Institution, Washington, DC 20013. 3 Smithsonian Marine Station at Fort Pierce, Fort Pierce, Florida 34949. * Corresponding author email: . 1
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Thalamita longifrons (Milne-Edwards, 1869) (Panel B, C, D) and its geminate, Red Sea endemic Thalamita murinae Zarenkov, 1971 (Panel F; voucher UF36721), are morphologically peculiar, poorly-studied members of the diverse, Indo-Pacific crab genus Thalamita (91 spp.; Family Portunidae). Morphological examination by Stephenson and Rees (1967) of a single T. longifrons specimen collected from soft coral revealed that this species has several “special additions to the basic [Thalamita] body plan,” which they interpret as “adaptations for [an] ectocommensal mode of life” on soft corals. These additions, which appear in both T. longifrons and T. murinae, include the presence of a distal spine on the ventral margin of the Bulletin of Marine Science
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merus and the propodus of each walking leg and a narrow, more lanceolate shaped dactyl on the posterior “swimming” legs. These morphological apomorphies, highlighted in Panel E, may allow these crabs to more firmly grasp their host, as illustrated in Panel C. However, such symbiotic relationships are rare in portunid crabs and subsequent work by Spiridonov and Neumann (2008) was unable to substantiate this association in either species. Yet few records exist for either species and these researchers were only able to evaluate nine specimens, most with no microhabitat data. Here, we report new field observations of T. murinae and T. longifrons from soft coral hosts, and summarize additional records that overall support a facultative commensal association between these crabs and soft coral. On 13 October, 2013, one of us (CSM) collected two juvenile T. murinae specimens (vouchers UF38211 and UF38212) at night from the primary stalk of a Litophyton soft coral (family Nephtheidae) encountered at a depth of 10 m on a fore reef near An-Numan, Saudi Arabia. On 10 October, 2014, one of us (CSM) collected two adult T. longifrons specimens (one pictured in Panel B and E, voucher USNM1294238) at night from separate colonies of Nepthea soft corals (one pictured in Panel A, voucher USNM1294237) encountered at a depth of 2 m off Ghizo Island, Solomon Islands (approximately 8.12572°S, 156.91929°E). Unlike most free-living portunids, both T. murinae and T. longifrons were slow to evade capture. Motivated by these observations, we compiled a list of 37 occurrence records for T. longifrons and T. murinae from museum material (26 records) and popular media generated by marine photographers (11 records; 1 from Debelius 1998, 4 from Burdick 2014, 6 from Poppe and Poppe 2015). This list documents 26 and 11 records for T. longifrons and T. murinae, respectively (See Online Appendix 1). Information on microhabitat was available for 24 records, of which 11 (45.8%) involved specimens found among soft coral (8 for T. longifrons and 3 for T. murinae). Seven of these host records involved crabs collected from or photographed on soft corals in the family Nephtheidae (e.g., Panel C, D). Five (45.5%) of the 11 photographic records depict crabs on soft coral (three on nephtheids). Correspondence with D Burdick (University of Guam, pers comm) and Ph Poppe (Conchology, Inc., pers comm) confirmed that their photographs reflect animals photographed in situ. Thirteen of the 26 museum records provide some microhabitat data; six (46.2%) indicating that crabs were taken from soft coral (four from neptheids). The records we summarize here support the conclusions of Stephenson and Rees (1967) and suggest that a facultative commensal association exists between these crabs and soft corals, especially nephtheids. Finally, this work presents the first formal photographic documentation of living color for T. longifrons and T. murinae, and our collection of T. longifrons in the Solomon Islands extends the range of this species. Acknowledgments We thank M Berumen for his invitation and funding (through King Abdullah University of Science and Technology) for FLMNH researchers to participate in several Red Sea expeditions. Special thanks to Ross Institute and CS Ross, Founder and Chair, for providing funding for this research (Solomon Islands, 2014). Photographs in Panel A and B were kindly provided by D Liittschwager (with permission); those in Panel C and D were kindly provided by Ph Poppe (with permission), and that in Panel F was kindly provided by G Paulay (with permission). This is contribution 1017 of the Smithsonian Marine Station at Fort Pierce.
Literature Cited Burdick D. 2014. guamreeflife.com [Internet]. Mangilao, Guam: Dave Burdick; 2 August 2014. Available from: http://www.guamreeflife.com/ Debelius H. 1998. Red Sea reef guide: Egypt, Israel, Jordan, Sudan, Saudi Arabia, Yemen, Arabian Peninsula (Oman, UAE, Bahrain). Frankfurt, Germany: IKAN. Poppe G, Poppe Ph. 2015. Poppe images: marine iconography of the Philippine Archipelago [Internet]. Lapu-lapu City, Philippines: Conchology, Inc.; copyright 1996–2015. Available from: http://www.poppe-images.com/ Spiridonov VA, Neumann V. 2008. Coral-inhabiting swimming crabs (Crustacea, Decapoda, Portunidae) of the Sudanese Red Sea. Org Divers Evol. 8(3):170e1–170e19. http://dx.doi.org/10.1016/j.ode.2007.06.005 Stephenson W, Rees M. 1967. Some portunid crabs from the Pacific and Indian oceans in the collections of the Smithsonian Institution. Proc US Nat Mus. 120:1–114. Date Submitted: 29 September, 2015. Date Accepted: 15 October, 2015. Available Online: 6 November, 2015.
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