Two new genera and a new species in the holothurian family Cucumariidae (Echinodermata: Holothuroidea)

<span style="font-family: CharterBdBT; font-size: xx-small;"><span style="font-family: CharterBdBT; font-size: xx-small;"><span style="font-family: CharterBdBT; font-size: xx-small;"><p>Two new genera,</p></span></span></span><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;"><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;">Trachycucumis </span></em></span></em><span style="font-family: CharterBdBT; font-size: xx-small;"><span style="font-family: CharterBdBT; font-size: xx-small;">and </span></span><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;"><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;">Trachasina, </span></em></span></em><span style="font-family: CharterBdBT; font-size: xx-small;"><span style="font-family: CharterBdBT; font-size: xx-small;">in the holothurian family Cucumariidae, are described. The former is erected to accommodate a new southern African cucumariid, here <span style="font-family: CharterBdBT; font-size: xx-small;">described as </span></span></span><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;"><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;">T. plettenbergi, </span></em></span></em><span style="font-family: CharterBdBT; font-size: xx-small;"><span style="font-family: CharterBdBT; font-size: xx-small;">from the southeast coast of South Africa, and the </span></span><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;"><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;">Trachythyone </span></em></span></em><span style="font-family: CharterBdBT; font-size: xx-small;"><span style="font-family: CharterBdBT; font-size: xx-small;">sp.<span style="font-family: CharterBdBT; font-size: xx-small;">Thandar (1991) from the northeast coast. </span></span></span><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;"><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;">Trachasina </span></em></span></em><span style="font-family: CharterBdBT; font-size: xx-small;"><span style="font-family: CharterBdBT; font-size: xx-small;">is currently monotypic and is erected to </span></span><span style="font-family: CharterBdBT; font-size: xx-small;"><span style="font-family: CharterBdBT; font-size: xx-small;"><span style="font-family: CharterBdBT; font-size: xx-small;">accommodate </span></span></span><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;"><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;">Trachythyone crucifera </span></em></span></em><span style="font-family: CharterBdBT; font-size: xx-small;"><span style="font-family: CharterBdBT; font-size: xx-small;">(Semper, 1869) which has remained erroneously in </span></span><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;"><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;"><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;">Trachythyone </span></em></span></em></span><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;"><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;"><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;">Trachythyone </span></em></span></em></span></em><span style="font-family: CharterBdBT; font-size: xx-small;"><span style="font-family: CharterBdBT; font-size: xx-small;">in being a warm-water genus with body wall spicules in the form of spinous </span></span></em><span style="font-family: CharterBdBT; font-size: xx-small;"><span style="font-family: CharterBdBT; font-size: xx-small;">for so long, despite several reservations. </span></span><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;"><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;">Trachycucumis </span></em></span></em><span style="font-family: CharterBdBT; font-size: xx-small;"><span style="font-family: CharterBdBT; font-size: xx-small;">differs from</span><span style="font-family: CharterBdBT; font-size: xx-small;"><span style="font-family: CharterBdBT; font-size: xx-small;">cross-shaped rods and multilocular plates with one end often prolonged as a spinous handle. <span style="font-family: CharterBdBT; font-size: xx-small;">The new species,</span></span></span><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;"><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;">T. plettenbergi </span></em></span></em><span style="font-family: CharterBdBT; font-size: xx-small;"><span style="font-family: CharterBdBT; font-size: xx-small;">differs from Thandar’s </span></span><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;"><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;">Trachythyone </span></em></span></em><span style="font-family: CharterBdBT; font-size: xx-small;"><span style="font-family: CharterBdBT; font-size: xx-small;">sp. in the absence of <span style="font-family: CharterBdBT; font-size: xx-small;">rosette-shaped deposits and the simplicity of the plates.</span></span></span><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;"><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;">Trachasina, </span></em></span></em><span style="font-family: CharterBdBT; font-size: xx-small;"><span style="font-family: CharterBdBT; font-size: xx-small;">on the other hand, is <span style="font-family: CharterBdBT; font-size: xx-small;"><span style="font-family: CharterBdBT; font-size: xx-small;">unique in having 10 equal tentacles and sparsely distributed spicules in the form of spinous crosses, unlike those of </span></span><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;"><em><span style="font-family: CharterBdBT-NormalItalic; font-size: xx-small;">Trachycucumis, </span></em></span></em><span style="font-family: CharterBdBT; font-size: xx-small;"><p><span style="font-family: CharterBdBT; font-size: xx-small;">and simple, thick, smooth, oval plates with few perforations and without any prolongations.</span></p></span></span></span></span>