Clownfish hosting anemones (Anthozoa, Actiniaria) of the Red Sea: new associations and distributions, historical misidentifications, and morphological variability

Michael L. Berumen,John E. Majoris,Morgan F. Bennett-Smith,Benjamin M. Titus

doi:10.1186/s41200-021-00216-6

Abstract

BackgroundThe Red Sea contains thousands of kilometers of fringing reef systems inhabited by clownfish and sea anemones, yet there is no consensus regarding the diversity of host anemone species that inhabit this region. We sought to clarify a historical record and recent literature sources that disagree on the diversity of host anemone species in the Red Sea, which contains one endemic anemonefish, Amphiprion bicinctus Rüppell 1830.ResultsWe conducted 73 surveys spanning ~ 1600 km of coastline from the northern Saudi Arabian Red Sea to the Gulf of Aden and encountered seven species of host anemones, six of which hosted A. bicinctus. We revise the list of symbionts for A. bicinctus to include Stichodactyla haddoni (Saville-Kent, 1893) and Stichodactyla mertensii Brandt, 1835 which were both observed in multiple regions. We describe Red Sea phenotypic variability in Heteractis crispa (Hemprich & Ehrenberg in Ehrenberg, 1834) and Heteractis aurora (Quoy & Gaimard, 1833), which may indicate that these species hybridize in this region. We did not encounter Stichodactyla gigantea (Forsskål, 1775), although the Red Sea is the type locality for this species. Further, a thorough review of peer-reviewed literature, occurrence records, and misidentified basis of record reports dating back to the early twentieth century indicate that it is unlikely that S. gigantea occurs in the Red Sea.ConclusionsIn sum, we present a new guide for the host anemones of the Red Sea, revise the host specificity of A. bicinctus, and question whether S. gigantea occurs in the central and western Indian Ocean.

Highlights

The Red Sea contains thousands of kilometers of fringing reef systems inhabited by clownfish and sea anemones, yet there is no consensus regarding the diversity of host anemone species that inhabit this region
The Red Sea contains over 2000 km of fringing reef habitat, but is only inhabited by one species of anemonefish, Amphiprion bicinctus Rüppell 1830, which ranges from the Gulf of Aqaba in the north to the Gulf of Aden in the south
More than 50% of all publications from the Red Sea come from the northern Gulf of Aqaba or Sinai Peninsula, but this region constitutes less than 2% of the total area of the Red Sea (Berumen et al 2013)

Summary

Introduction

The Red Sea contains thousands of kilometers of fringing reef systems inhabited by clownfish and sea anemones, yet there is no consensus regarding the diversity of host anemone species that inhabit this region. We sought to clarify a historical record and recent literature sources that disagree on the diversity of host anemone species in the Red Sea, which contains one endemic anemonefish, Amphiprion bicinctus Rüppell 1830. Distributions, and symbiosis have been thoroughly investigated using clownfish and sea anemone species from many tropical regions of the world (e.g. Richardson et al 1997; Srinivasan et al 1999; Camp et al 2016; Titus et al 2020), comparatively little work on the subject has been conducted in the Red Sea (but see, e.g., Chadwick and Arvedlund 2005, Huebner et al 2012, Nanninga et al 2014). Studies from the Red Sea and Gulf of Aden typically list three to five host species for A. bicinctus: Entacmaea quadricolor (Leuckart in Rüppell & Leuckart, 1828), Heteractis aurora (Quoy & Gaimard, 1833), Heteractis crispa (Hemprich & Ehrenberg in Ehrenberg, 1834), Heteractis magnifica (Quoy & Gaimard, 1833), Stichodactyla mertensii (Brandt, 1835), and Stichodactyla gigantea (Forsskål, 1775) (Red Sea host combinations from Fishelson 1970, Fautin and Allen, 1992, Nanninga et al 2014, Emms et al 2020; Fig. 1)

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Conclusion