Amphoriscus semoni Breitfuss, 1896

Van Soest, Rob W. M. & De Voogd, Nicole J., 2015, Calcareous sponges of Indonesia, Zootaxa 3951 (1), pp. 1-105 : 93-95

Amphoriscus semoni Breitfuss, 1896

Figures 68a–f

Amphoriscus semoni Breitfuss, 1896b: 435 ; Breitfuss, 1898: 221. Material examined. ZMA Por. 08073, Indonesia, Nusa Tenggara, Sumbawa, Bay of Sanggar, 8.32°S 118.24°E, depth 1 m, sea grass meadow, snorkeling, coll. F. Leys, Indonesian-Dutch Snellius II Expedition stat. 114/01, 21 September 1984.

Description. A small group of elongated thin-walled curved tubes ( Fig. 68a ), with smooth surface, live color green. The three are basally connected on the surface of a small limestone fragment, but are otherwise free. Length of longest tube 2.5 cm, diameter 0.4 cm. Consistency fragile, easily damaged.

Histology. Syconoid aquiferous system ( Fig. 68b ).

Skeleton. Inarticulate ( Fig. 68b ). Very organized. The ectosomal skeleton is formed by the paired and unpaired actines of giant tetractines. The apical actines of these form the choanosomal skeleton, together with the unpaired actines of the subatrial triactines. Atrial skeleton is formed by the paired actines of the subatrial triactines and a thin layer of atrial tetractines. The wall of the tubes is thin, often thinner than the length of the apical actines of the giant tetractines (less than 600–800 µm in length), which may protrude into the atrial lumen along with the apical actines of the small atrial tetractines.

Spicules. ( Figs 68c–f ) Large sagittal tetractines, small more or less equiactinal tetractines, large and small sagittal triactines.

Large tetractines ( Fig. 68c ), with long apical actine and almost equiangular equiactinal paired and unpaired actines. Unpaired actines 122– 203.8 –271 x 13– 15.6 –18 µm, paired actines, 210– 432.9 –602 x 15– 18.4 –23 µm, apical actines 378– 517.1 –600 x 18– 21.5 –35 µm.

Small tetractines ( Fig. 68e ), basal system approximately equiangular equiactinal, smaller apical actines, unpaired actines 54– 113.6 –174 x 6– 8.7 –11 µm, paired actines 48– 106.6 –175 x 5– 7.0 –11 µm, apical actines 9– 44.6 –84 x 5– 5.9 –8 µm.

Triactines ( Figs 68d, f ), sagittal, in a wide size range, possibly divisible in two size classes, unpaired actines overall 72– 241.5 –372 x 5– 11.6 –16 µm, paired actines overall 48– 158.5 –222 x 5– 8.6 –11 µm.

Ecology. Shallow water.

Distribution. Indonesia ( Ambon, Sumbawa).

Remarks. The specimens conform closely with the Ambon material of Breitfuss (1896b). He described the holotype as shiny white, but his material was preserved without field data (received from W. Weltner who passed it on from the collector R. Semon). The length of the choanosomal (apical) actine of the giant tetractines is given as 520–790 µm, whereas in our material this did not exceed 600 µm.

Genus Leucilla Haeckel, 1872

Figures

FIGURE 68. Amphoriscus semoni Breitfuss (1896), ZMA Por. 08073, a, habitus (scale bar = 1 cm), b, histological cross section showing syconoid aquiferous system and inarticulate skeleton (scale bar = 200 µm); left side: ectosomal skeleton formed by the paired and unpaired actines of giant tetractines, right side: atrial skeleton of triactines and tetractines, c–f, SEM images of spicules, c, giant tetractines, d, large sagittal triactines of the choanosomal / subatrial skeleton, e, atrial tetractines, f. small subatrial sagittal triactine.