Heteroxenia

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 : 145-146

Heteroxenia

Heteroxenia ghardaqensis is supported as a monophyletic species by both genes. The species can be distinguished easily from all other samples by the dark brown colour of the clearly branched colonies and by the lack of sclerites ( Reinicke 1995). Interestingly, not all colonies showed polyp dimorphism, reflecting Gohar’ s (1940) statement that siphonozooids appear during the reproductive season in spring. Thus, the use of this trait as a diagnostic character is limited.

All 13 specimens identified a priori as Heteroxenia fuscescens have the same haplotype of the SRP54 gene and form a monophyletic group supported by a posterior probability value of 1 and ML bootstrap value of 100 in the analysis. This result is not supported by the analysis of the mitochondrial gene fragment, where H. fuscescens is paraphyletic, clustering with other members of the genera Heteroxenia and Bayerxenia . All 13 investigated specimens had siphonozooids, the same number of rows of pinnules (4) and a large number of pinnules at the outer row. Additionally, the sclerites exhibited a uniform diameter in all specimens (22×12 μm). Noticeable is a variable growth form, which seems to be related to their locality (Figure S5 and S6): The specimens collected at a depth of 8 m (“moray eel garden”) formed single cylindrical colonies (<7 cm) with a convex capitulum and dense, feathery and pulsating polyps (Figure S5 A, B). At the lagoon of Dahab, similar specimens were collected at a depth of 12 m with much longer and thinner anthocodiae (Figure S5 C, D), similar to specimens of the genus Bayerxenia within clade 5. Compared to the latter, specimens from “ Sinai front” (3 m depth) (Figure S5 E, F) and “Nabaq” (1 m depth) (Figure S6 A, B) had a much smaller colony size of 4 cm, very short anthocodiae and did not appear as cylindrical as the first two morphs. These latter Heteroxenia specimens, preliminarily assigned to H. fuscescens , had a similar growth form as those described as Heteroxenia elisabethae by Reinicke (1995). But this species distinction is not supported by our genetic data. Specimens collected in “Nabaq” appeared in aggregations slightly underneath the surface. On two morphospecies the nudibranch Phyllodesmium hyalinum, Ehrenberg (1831) was found in a pouch between the siphonozooids (Figure S6 B). No evaluation of the morphological characters was possible for Heteroxenia sp. EU 006856 (clade 5) from GenBank. Since it groups together in clade 5 with Bayerxenia specimens, it may possible be a misidentified specimen.