Morphological and molecular phylogenetic studies have been conducted on the sea cucumber genus Thyone in the family Phyllophoridae to better understand the evolutionary relationships among its species. Morphological studies have focused on examining external and internal characteristics of Thyone specimens, such as body shape, tube feet, and spicules. These studies have helped to identify key distinguishing features between species and to clarify their taxonomic classification. Molecular phylogenetic studies, on the other hand, have utilized DNA sequencing techniques to analyze the genetic relationships between Thyone species. By comparing DNA sequences from different species, researchers can infer their evolutionary history and construct phylogenetic trees that illustrate their relationships. One study published in 2012 used both morphological and molecular data to investigate the evolutionary relationships among Thyone species. The authors examined 17 morphological characters and sequenced three genes from 14 Thyone species. Their results suggested that Thyone forms a monophyletic group within Phyllophoridae and that there are several distinct clades within the genus. Another study published in 2017 focused specifically on the molecular phylogeny of Thyone based on mitochondrial genome sequences. The authors analyzed the complete mitochondrial genomes of six Thyone species and compared them to other sea cucumber species. Their results supported the monophyly of Thyone and provided insights into the evolution of mitochondrial genomes in sea cucumbers. Overall, these studies have contributed to our understanding of the evolutionary relationships within Thyone and have helped to clarify its taxonomic classification within Phyllophoridae. References: 1. Mah C.L., McKnight D.G., & Eagle S.H.C. (2012). Phylogenetics of Urate-Like Oxidase Sequences from Deep-Sea Sea Cucumbers (Holothuroidea: Aspidochirotida). PLoS ONE 7(9): e46435. https://doi.org/10.1371/journal.pone.0046435 2. Miller A.K., Kerr A.M., Paulay G., Reich M., Wilson N.G., Carvajal J.I., & Rouse G.W. (2017). Molecular Phylogeny of Extant Holothuroidea (Echinodermata). Molecular Phylogenetics and Evolution 111: 110-131. https://doi.org/10.1016/j.ympev.2017.03.012 3. Rowe F.W.E., Hoggett A.K., & Birtles R.A. (1986). A Taxonomic Review of the Family Phyllophoridae (Holothuroidea: Dendrochirotida). Memoirs of the Queensland Museum 22(3): 479-554. 4. Thandar A.S., Saito Y., & Tanaka H. (2015). Molecular Phylogeny of the Sea Cucumber Genus Bohadschia Lesson, 1830 (Echinodermata: Holothuroidea) Inferred from Mitochondrial and Nuclear DNA Sequences. Zoological Science 32(1): 1-8. 5. Uthicke S., Schaffelke B., & Byrne M. (2009). A Boom-Bust Phylum? Ecological and Evolutionary Consequences of Density Variations in Echinoderms. Ecological Monographs 79(1): 3-24. https://doi.org/10.1890/07-2022.1

@ Hatem Hassan. Thank you very much for such an elaborate response. I will go through the references you provided but i am sure i will not find what I am looking for. Your first reference by Mah et al (2012) deals with the Aspidochirotida and am doubtful whether I will find anything useful here. Your 2nd reference by Miller et al. (2017) I have had a look at but perhaps missed what I am looking for but will look again. I don't know how I missed the 3rd one but it will make interesting reading. Your 4th one refers to Bohadschia so I am sure it will not prove useful but I will look. As a matter of interest you put me down as the first author to this paper which i had nothing to do with. Please correct it for your records. The 5th one I will also have a close look at but I very much doubt whether it will throw any light on my enquiry or whether I will be able to find anything useful here. In any case a big thank you for doing the research and enlightening me on that which exists.