Heteropia minor Burton, 1930

Van Soest, Rob W. M. & De Voogd, Nicole J., 2015, Calcareous sponges of Indonesia, Zootaxa 3951 (1), pp. 1-105 : 87-91

Heteropia minor Burton, 1930

Figures 63a–c , 64a–d , 65a–f

Heteropia striata var. minor Burton, 1930: 4 .

Pericharax sp. ; Colin & Arneson, 1995: 61 photo 233; Gosliner et al., 1996: 17, photo 7; Erhardt & Baensch, 1998: 23.

Material examined. Holotype ZMA Por. 00143, Siboga Expedition Stat. 282, Timor-Leste, Timor , anchorage between Nusa Besi and the NE point of Timor, 8.42°S 127.3066°E, depth 27–54 m, trawl, bottom sand with corals and coralline algae, coll. Siboga Expedition stat. 282, 15–17 January 1901; three slides of the holotype: BMNH 1929.8.30.3a.

Additional specimens. ZMA Por. 06536, Indonesia, Komodo , N Cape, 8.4833°S 119.5683°E, depth 30 m , SCUBA, coll. H.A. ten Hove, Indonesian-Dutch Snellius II Expedition stat. 096/04, 19 September 1984 ; ZMA Por. 08391, Indonesia, Komodo lagoon, 8.5833°S 119.57°E, depth 4–11 m , SCUBA, coll. R. W.M. van Soest, Indonesian-Dutch Snellius II Expedition stat. 79 / III/16 , 18 September 1984 ; ZMA Por. 08955, Indonesia, Saleyar, Bahuluang , 6.45°S 120.43°E, depth 10–15 m , SCUBA, coll. R. W.M. van Soest, Indonesian-Dutch Snellius II Expedition stat. 169/IV/36, 30 September 1984 ; ZMA Por. 16835, Indonesia, North Sulawesi, Donggala , 0.6981°S 119.7713°E, depth 15 m , SCUBA, coll. S. Weinberg, 30 August 1995 ; RMNH Por. 1872, Indonesia, NE Kalimantan, Berau Islands, lighthouse Panjang , Island, NE side, 2.3873°N 118.2094°E, depth 10–15 m , SCUBA, coll. B.W. Hoeksema, #BER14/091003/082, 9 October 2003 ; RMNH Por. 2164, Indonesia, Central Sulawesi, Donggala, South Atoll , 0.69°S 119.7°E, depth 15–20 m , SCUBA, coll. N.J. de Voogd, #DG/240601/266, 24 June 2001 ; RMNH Por. 3603, Indonesia, N Sulawesi, off Manado, Nain Islands , Jelan Masak , 1.7567°N 124.7857°E, depth 5 m , SCUBA, coll. N.J. de Voogd, # MD13 /190502/114, 19 May 2002 ; RMNH Por. 5268, Indonesia, Ternate, Sulamadaha Beach , 0.8632°N 127.3345°E, depth 5–10 m , SCUBA, coll. N.J. de Voogd, #TER.04/261009/NV019, Ternate-Halmahera Expedition 2009, 26 October 2009 ; RMNH 9193 , Indonesia, Ternate, off Danau Laguna , 0.7583°N 127.3498°E, depth 12 m , SCUBA, coll. N.J. de Voogd, # TER.02/251009/, Ternate-Halmahera Expedition 2009, 25 October 2009 ; RMNH 9194 , Ternate, Kampung Cina, Tapak 2, 0.7875°N 127.3435°E, depth 10–15 m , SCUBA, coll. N.J. de Voogd, #TER.06/271009/, Ternate-Halmahera Expedition 2009, 27 October 2009 ; RMNH 9349 , Indonesia, Papua, Raja Ampat , 0.5695°S 130.2739°E, depth 10–20 m , SCUBA, coll. L.E. Becking, #RAJ67/ LE243 , 7 December 2007 .

Description. Short-stalked, thin-walled, sac-shaped or balloon-shaped sponge ( Figs 63a–b ), in life limp. When taken out of the water, the interior ‘empties’ and the opposite walls may stick together to form a double-walled envelope ( Fig. 63c ). In alcohol the walls become rigid and very easily damaged, or torn. Color red, dark red, wine red, brown red in life, whitish, cream or yellowish in preserved condition. What is left of the holotype is a tiny tube, of which most spicules are ‘corroded’. Sections and dissociated spicule preparations in the collection of the Natural History Museum, London, are an important part of the type material.

Histology. Sylleibid aquiferous system, possibly syconoid in some parts.

Skeleton. ( Figs 64a–d ) In cross section from exterior to atrial cavity, there is an ectosomal cortex built from tangential triactines, a variable amount of tangential long diactines ( Fig. 64d ), and parasagittal triactines with the unpaired actine directed proximally (inwards), and the paired actines carrying the diactines. The choanosomal skeleton is inarticulate ( Figs 64b–c ) and consists of the longest of the paired actines of the cortical para/ pseudosagittal triactines and the unpaired actines of subatrial sagittal tetractines and triactines.

The atrial skeleton is composed of the paired actines and tangentially arranged unpaired actines of predominantly tetractinal sagittal atrial spicules, strengthened by the paired actines of smaller atrial tetractines whose apical actines protrude into the atrial cavity ( Fig. 64b ).

Spicules. ( Fig 65a–f ) Equiactinal triactines, pseudosagittal triactines, sagittal triactines, sagittal tetractines, diactines.

Ectosomal diactines ( Fig. 65a ) up to 264– 724. 7– 1420 x 4 – 14.2 –22 µm. Holotype: 340–110 x 11–22 µm; additional specimens 264– 1420 x 4–20 µm.

Ectosomal cortical triactines ( Fig. 65b ), usually characteristic equiactinal or slightly sagittal tripods, unpaired actines 99– 140. 3–252 x 4– 5.4 –7 µm, paired actines 75– 99.7 –150 x 4– 4.8 –6 µm. Holotype: unpaired actines 135– 177 x 5–7 µm, paired actines 55–138 x 3–6 µm; additional specimens, unpaired actines 99–252 x 4–7 µm, paired actines 55–150 x 4–6. Overall actines (paired and unpaired) 55–252 x 3–7 µm.

Subcortical para/pseudosagittal triactines ( Fig. 65c ), with the paired actines at different planes with regard to the unpaired actines, and occasionally abruptly curved in the middle, or one of the paired actines may be ‘wavy’; unpaired actines 66– 159.1 –242 x 5– 6.6 –8 µm, paired actines, unequal in length but only barely so, 48– 101.8 –135 x 4– 5.5 – 7 mm. Holotype: unpaired actines 123–242 x 5–8 µm, paired actines 75–133 x 5–7 µm. Additional specimens: unpaired actines 66–222 x 5–8 µm, paired actines 72–132 x 4–6 µm.

Subatrial sagittal triactines ( Fig. 65d ), relatively rare, unpaired actines 96– 226.2 –450 x 5– 6.3 –9 µm, paired actines 81– 152.4 –300 x 5– 5.9 –6.5 µm. Holotype: unpaired actines 96–222 x 6–7 µm, paired actines 102–240 x 5– 6.5 µm. Additional specimens: unpaired actines 153–420 x 5–9 µm, paired actines 81–300 x 5–6 µm.

Subatrial sagittal tetractines ( Fig. 65e ), unpaired actines 186– 330.6 –570 x 5– 6.4 –9 µm, paired actines 90– 180.3 –324 x 6– 6.7 –9 µm, apical actines 10– 19.8 –57 x 4– 4.8 –6 µm. Holotype: unpaired actines 186–390 x 5–7 µm, paired actines 90–186 x 4–7 µm, apical actines 15–57 x 4–6 µm. Additional specimens: unpaired actines 216–570 x 6–9 µm, paired actines 120–324 x 6–9 µm, apical actines 10–21 x 4–6 µm.

Atrial sagittal tetractines ( Figs 65f, f 1 ), unpaired actines 122– 182.6 –228 x 5– 6.5 –8 µm, paired actines 63– 129.0–180 x 4.5– 5.3 –7 µm, apical actines 27– 51.5 –78 x 3– 4.3 –5 µm. Holotype: unpaired actines 186–216 x 5–6.5 µm, paired actines 96–180 x 4.5–6 µm, apical actines 30–66 x 3–6 µm. Additional specimens: unpaired actines 122–228 x 6–8, paired actines 63–120 x 5–7 µm, apical actines 27–78 x 4–5 µm.

Ecology. In coral reef localities, at depths between 4 and 54 m.

Distribution. Indonesia, Papua New Guinea.

Remarks. Burton (1930) assigned this species to the genus Heteropia , but according to the Systema Porifera (Borojevic et al. 2002b) that genus has an articulate skeleton unlike the present Indonesian material, and the subcortical triactines should be genuine pseudosagittal spicules, whereas our specimens including the holotype in that position show predominantly pseudosagittal spicules appearing almost parasagittal. We propose to extend the content of Heteropia to accommodate the present species.

Heteropia striata Hôzawa, 1916 , of which the present species was deemed a ‘variety’ by Burton, has indeed a certain similarity with our specimens in skeletal and spicule characters, and like our species it has an inarticulate skeleton. However, the shape is more definitely simply tubular, without the distended middle part, there may be an oscular fringe, lacking in our specimens, the aquiferous system is more elaborately sylleibid, with extensively branched chambers, it has larger and much thicker ectosomal oxeas (up to 2000 x 90 µm), the tangentially arranged atrial spicules are predominantly triactinal (not tetractinal as in our specimens), and most spicule measurements of all categories differ from those of the present material. There can be little doubt that this is a different species.

Genus Vosmaeropsis Dendy, 1893a

Figures

FIGURE 1. Map of Indonesia and adjacent countries showing approximate distribution of the sample location. Each white square represents one or more localities, and one or more specimens. Detailed locality positions are provided in the material examined data with each species (Free Edition map courtesy www.primap.com)

FIGURE 63. Heteropia minor Burton (1930), a, habitus in situ of RMNH Por. 9194 from Ternate (photo N.J. de Voogd), b, habitus in situ of RMNH Por. 1872 from the Berau region (photo B.W. Hoeksema), c, preserved specimens of sample RMNH Por. 9194 from Ternate (scale bar = 1 cm).

FIGURE 64. Heteropia minor Burton (1930), light microscopic sections, a, cross section of tube wall of ZMA Por. 08955 from Komodo showing inarticulate skeleton (scale bar = 200 µm), b, detail of cross section of ZMA Por. 08955 showing cortical triactines, pseudosagittal triactines, subatrial triactines and atrial tetractines (scale bar = 100 µm), c, BMNH 1929.8.30.3 cross section of holotype (ZMA Por. 00143) from Timor Leste showing essentially the same structure and spicules as in (b) (scale bar = 100 µm), d, BMNH 1929.8.30.3 tangential surface section of holotype (ZMA Por. 00143) showing cortical triactines and diactines (scale bar = 200 µm).

FIGURE 65. Heteropia minor Burton (1930), SEM images of the spicules of RMNH Por. 9194, a, cortical diactines, b, cortical (tripod-like) triactines, c, subcortical pseudosagittal / parasagittal triactine, d, subatrial triactine, e, subatrial tetractine, f, f1, atrial tetractines.