Arthuria tenuipilosa ( Dendy, 1905 )

Arthuria tenuipilosa ( Dendy, 1905) View in CoL

Figures 10a–f View FIGURE 10

Leucosolenia (Clathrina) tenuipilosa Dendy, 1905: 227 , pl. XIII fig. 9.

Clathrina tenuipilosa View in CoL ; Klautau & Valentine, 2003: 40 View Cited Treatment , fig. 32.

Arthuria tenuipilosa View in CoL ; Klautau et al. 2013: 12.

Material examined. ZMA Por. 15509b, Indonesia, Indonesia, SE Sulawesi, SW Salayar, NW coast of Pulau Guang , 6.35°S 120.45°E, depth 3–4 m GoogleMaps , SCUBA, coll. H.A. ten Hove, Indonesian-Dutch Snellius II Expedition stat. 152/II/ Cave 1/A3, 28 September 1984 .

Description. White mass of loosely anastomosed tubes ( Fig. 10a View FIGURE 10 ), size 3 x 1.5 x 0.5 cm. Water-collecting tubes are absent. Wall of tubes microscopically echinated by hairy-thin diactines ( Figs 10b–c View FIGURE 10 ).

Skeleton. ( Fig. 10b View FIGURE 10 ) The tube walls consist of a thin layer of triactines and tetractines.

Spicules. ( Figs 10d–f View FIGURE 10 ) Triactines, tetractines, diactines.

Triactines ( Fig. 10d View FIGURE 10 ) equiangular equiactinal, 81– 107.1 –119 x 8– 8.9 –10.5 µm.

Tetractines ( Fig. 10e View FIGURE 10 ), with equiangular equiactinal basal radiate system, actines 89– 103.6 –121 x 8– 8.7 –10 µm, apical actines 62–100 x 6–6.5 µm.

Diactines ( Fig. 10f View FIGURE 10 ), with slightly swollen endings ( Fig. 10f View FIGURE 10 1 View FIGURE 1 ) on one side and thinly pointed endings on the opposite side, usually broken, 350–422 x 2.5–3 µm.

Ecology. On the upper wall of a shallow-water cave.

Distribution. Indonesia, Sri Lanka.

Remarks. The spicule size data of our specimen conform closely to those given by Dendy (1905: 227) for the type material, but differ from the measurements of Klautau & Valentine (2003: 41) taken from a paratype in having on average longer and slightly thinner actines. Trichoxeas described by Klautau & Valentine (2003: 41) are thinner (only 0.3 µm) than the diactines we measured in our material.

Clathrina luteoculcitella Wörheide & Hooper, 1999 also has a fringe of diactines sticking out of the tubewalls, but that species has no tetractines and the live color is yellow.

Ernstia indonesiae sp.nov. described below has similar habitus and general spiculation, but the actines of both triactines and tetractines are twice as long and thick, there is a complement of sagittal tri-and tetractines. The diactines are also longer and thicker and do not stick out.