Xenia, , Lamarck, 1816

Reinicke Heike Wägele Ralph Tollrian Florian Leese, Kristina Stemmer Ingo Burghardt Christoph Mayer Götz B., 2013, Morphological and genetic analyses of xeniid soft coral diversity (Octocorallia; Alcyonacea), Organisms Diversity & Evolution (New York, N. Y.) 13 (2), pp. 135-150 : 143-145

Xenia

The sister taxon relationship of Xenia sp. 1 and Xenia sp. 2 (clade 2 in Fig. 3 ) is characterised by an extremely low sequence divergence for both molecular markers (0.3 % and 0 % for SRP54 and ND6/ND3, respectively). This is in contrast to morphological data indicating two distinct species: Xenia sp. 1 lacked sclerites and the polyps exhibited a very low number of pinnules at the outer row of the tentacles (Figure S2 A, B). In Xenia sp. 2 , sclerites were present. Since the same preservatives were used, it seems very unlikely that the absence of sclerites in Xenia sp. 1 is an artefact due to preservation. But possibly this colony was very young and sclerites have not yet been formed. As a consequence, the presence or absence of sclerites, as a species-specific character, has to be considered carefully (see below).

The morphospecies Xenia sp. 3 was distinguished from Xenia sp. 4 with the aid of size differences in the syndete pulsating polyps)

CLADE CLADE 1 Ovabunda Ovabunda Ovabunda Ovabunda Ovabunda Ovabunda Ovabunda Ovabunda Ovabunda Ovabunda Ovabunda Ovabunda Ovabunda Ovabunda Ovabunda Ovabunda macrospiculata macrospiculata faraunensis faraunensis macrospiculata macrospiculata faraunensis faraunensis faraunensis macrospiculata macrospiculata macrospiculata macrospiculata macrospiculata macrospiculata Ovabunda faraunensis Ovabunda faraunensis sp sp.. 2 1 _ _ 01 01 2 Xenia Xenia sp sp.. 2 1 _ _ 01 Xenia 3 Xenia Xenia Xenia Xenia Xenia Xenia Xenia Xenia Xenia Xenia Xenia _ 10 Xenia _ 02 _ 03 _ _ 04 05 4 _ 06 _ 07 _ 08 _ 09 _01 _02 _03 _04 _05 _06 _07 _09 _ _ 10 11 5 01 03 05 06 09 _01 006856 6 sp. 2_04 sp.2_08 sp.2_10 7 sp. 2_ 11 sp. 2_12 fuscescens _ 01 fuscescens _ 02 fuscescens _ 03 fuscescens _ 04 fuscescens _ 05 fuscescens _ 06 fuscescens _ 07 8 fuscescens _ 08 fuscescens _ 10 fuscescens _ 11 fuscescens _ 12 fuscescens _ 13 fuscescens _ 14 9 Sympodium caeruleum EU 006855 Alcyonium digitatum

(6 cm versus 2 cm, respectively). No differences between the two species were observed in the mitochondrial gene fragment, except that the sequence reads of Xenia sp. 3 were shorter than those from Xenia sp. 4 and terminal Ns had to be added. In the SRP54 gene two distinct subclades are found ( Fig. 3 ): one subclade encompassing specimens of Xenia sp. 3 and Xenia sp. 4 and the other containing only two Xenia sp. 3 specimens. Distinction of these two species is mainly based on the size of the sclerites and the syndete. Both species (some specimens of Xenia sp. 3 and both specimens of Xenia sp. 4 ) were collected at exactly the same locality, i.e. the water pipeline of the Lizard Island Research station. Following the results of the genetic analyses, it seems unlikely that Xenia sp. 3 and 4 represent two distinct species. Morphological differences may be a consequence of daily exposure to air, wave action or other ecological factors. Nevertheless, a recent speciation process might have resulted in the two Xenia sp. 3 specimens ( Xenia sp. 3 _09 and Xenia sp. 3 _10) with

10,000 replications. The non-vanishing terminal branch lengths in multifurcations of identical sequences are an artefact of the Bayesian inference as well as due to the occurrence of Ns in the alignment morphologically similar but genetically distinct features from all other specimens of clade 3.

All other specimens assigned to the genus Xenia based on the absence of siphonozooids ( Xenia sp. 5 , sp. 6a and 6b) cluster within the dimorphic genera Heteroxenia and Bayerxenia .

Figures

Fig. 3 Bayesian phylogenetic tree of Ovabunda, Xenia, Bayerxenia and Heteroxenia. Node labels indicate Bayesian posterior probabilities and maximum likelihood bootstrap support values (in italics) based on