Hexactinellida from the Perth Canyon, Eastern Indian Ocean, with descriptions of five new species Author Tabachnick, Konstantin Author Fromont, Jane Author Ehrlich, Hermann Author Menshenina, Larisa text Zootaxa 2019 2019-09-02 4664 1 47 82 journal article 25821 10.11646/zootaxa.4664.1.2 aa4ab61b-5bb7-4a74-857b-e92447ed1425 1175-5326 3383496 4434E866-7C52-48D1-9A6B-1E6220D71549 Walteria flemmingi Schulze, 1886 Material examined . Australia : Western Australia : WAM Z92536, 1 specimen , Perth Canyon , Site D ( 32 o 9’58.188’’S , 114 o 50’38.754’’E , Figure 1 ), 987 m , A. Hosie , ROV, 09/03/2015 , RV Falkor station FPC15_D07_S006 . Description. Body, Figure 16 , 17 . Body is an elongate sac or tube tapering to an attachment point basally and to a terminal oscula apically. Walls are thin and rigid. Overall height 900 mm and diameter 250 mm . Elongate lateral processes extend at right angles from the sponge body. The wall of the sponge is an intricate net-like lattice structure. Texture is rigid and colour is creamy white. FIGURE 16. Walteria flemmingi A, in situ image, Perth Canyon. B, Atrial surface, WAM Z92536. Spicules. Megascleres. Choanosomal spicules are diactins at least 0.5–15 mm long (some can be longer)/ 0.007 – 0.040 mm in diameter and rare tauactins. They have conically pointed rough outer ends. The small choanosomal diactins have a widening in the middle, the large ones have numerous synapticular junctions. Dermalia are hexactins with rough rays, the distal ray is usually clavate, other rays have rounded outer ends. The distal rays of the dermal hexactins are 0.048 –0.229 mm long (n=26, avg: 0.138 mm , std: 0.047 mm ), the tangential rays are 0.074 –0.178 mm long (n=26, avg: 0.122 mm , std: 0.029 mm ), the proximal ray is 0.167 –0.548 mm long (n=26, avg: 0.322 mm , std: 0.094 mm ), the diameter of these rays is 0.007 –0.050 mm . Atrialia are most likely represented by minute spots at the intersections of the skeletal beams, seen from the atrial surface ( Figure 16b ). They are pentactins and stauractins with rounded outer ends and a roughened surface in parts, usually close to the ends. They have tangential rays 0.037 –0.189 mm long (n=9, avg: 0.083 mm , std: 0.061 mm ) and about 0.010 mm in diameter. FIGURE 17. Walteria flemmingi WAM Z92536, external morphology (scale 50 mm). Microscleres. Discoidal microscleres are represented by large and small discasters and small discohexasters. The rare large discasters are 0.085 –0.104 mm in diameter (n=3, avg: 0.095 mm , std: 0.010 mm ), diameter of the central spherical part composed of the primary rays is 0.014 –0.022 mm (n=3, avg: 0.018 mm , std: 0.005 mm ). Small discasters and discohexasters are 0.058 –0.076 mm in diameter (n=27, avg: 0.066 mm , std: 0.005 mm ), diameter of the central spherical part composed of the primary rays in the discasters and diameter of the primary rosette is 0.011 –0.022 mm (n=27, avg: 0.014 mm , std: 0.003 mm ). Diameter of the primary rosette of the graphiocome is 0.022 –0.029 mm (n=12, avg: 0.025 mm , std: 0.002 mm ), the length of the secondary ray is 0.108 –0.185 mm (n=12, avg: 0.152 mm , std: 0.019 mm ). Spiny oxyhexactins have rays 0.031 -0.149 mm (n=24, avg: 0.087 mm , std: 0.039 mm ). Oxyhexasters are 0.068 –0.083 mm in diameter (n=11, avg: 0.078 mm , std: 0.005 mm ), diameter of the primary rays 0.009 –0.016 mm (n=11, avg: 0.012 mm , std: 0.002 mm ). Onychohexasters are 0.072 –0.079 mm in diameter (n=4, avg: 0.077 mm , std: 0.003 mm ), diameter of the primary rays are 0.009 –0.014 mm (n=4, avg: 0.011 mm , std: 0.002 mm ). Floricomes are 0.065 –0.079 mm in diameter (n=2, avg: 0.072 mm , std: 0.010 mm ), diameter of the primary rays are 0.011 –0.014 mm (n=2, avg: 0.013 mm , std: 0.003 mm ). Remarks. The newly found specimen from Perth Canyon is the first report of a representative of Walteria in the Indian Ocean. This genus can be easily divided into two species mostly by external body shape: W. flemmingi has an ovoid or clavate body with irregular, usually not rounded or oval lateral oscula; W. leuckarti has a thin and long tubular body with lateral rounded or ovoid oscula. The new specimen belongs to W. flemmingi . It contains onychohexasters and floricomes previously described in some specimens from the South Pacific ( Tabachnick, 2002b ; Reiswig & Kelly, 2018 ). It also contains oxyhexasters and rare large spherical discohexaster microscleres reported for the specimens off New Zealand ( Reiswig & Kelly, 2018 ). It is very difficult to find the atrial spicules, likely the atrial areas are represented by small spots on the intersections of the main skeletal beams composed of fused and unfused diactins from the atrial surface, which contain few pentactins and stauractins. The observed variations in microsclere content and dimensions do not notably differ from previous descriptions of representatives of this species. Distribution. This is the first record of the genus Walteria in the Indian Ocean. Previously it has been recorded in the Western Pacific from Japan to north east of New Zealand and in South Australia at depths of 370–4732 meters ( Tabachnick, 2002b ; Reiswig & Kelly 2018 ; MacIntosh et al. 2018 ).