Placospongia melobesioides Gray, 1867 by monotypy

Encrusting to branching growth forms. Small encrustations of 3 cm² to large surfaces of >2m² to branching individual with total size of up to 45cm in length and branch diameter between 0.25-1.5cm. Total size of specimens is hard to establish as parts of the body may be encrusting within cracks. Dried material is hard, alcohol preserved and live specimens remain compressible as the choanosome is of more pliant material than the cortex. The surface is made up of smooth cortical plates separated by contractible grooves which form a kind of network on the surface while these are firmly closed in preserved specimens. See Vosmaer and Vernhout (1902) and Rützler (2002) for an extensive description of the genus. In live specimens grooves are open and oscules are visible inside contractile ridges, running between plates. Live color white, cream, orange, reddish brown to dark black-brown (Fig. 1, 2) and come color is usually retained after alcohol preservation. The contact lines between the plates ridge up slightly and are generally a different shade of the color of the plates.

Skeleton. The cortical plates consist of densely packed selenasters and can also contain auxiliary microscleres. Developmental stages of selenasters occur throughout the choanosome. Tylostyle tracts support the margins of the cortical plates. In branching specimens radial tylostyle tracts run from the centre core (consisting of densely packed selenaster) to the cortical plates, in encrusting specimens tracts run in direction from substrate to cortex. The sharp ends of the smaller tylostyles are projected beyond the cortex surface. Microscleres occur in the cortex and scattered in choanosomal skeleton. For a detailed description of external morphology and anatomy see Vosmaer and Vernhout (1902).

Spicules. Megascleres are tylostyles in two size classes, microscleres are selenasters, and can include choanosomal and ectosomal spirasters (slender-spined streptasters and acanthose microrhabds), spherasters, and/or spherules. Selenasters often remain pigmented after treatment with bleach or nitric acid.

Holotype. NSMT-Po R288 (National Museum of Nature and Science, Tokyo, Japan), Japan, Kannonzuka-dashi, Amadaiba, Sagami Bay, 62–67m. depth.

HolotypeNSMT-Po R288 encrusting specimen in three pieces of 1–2cm² and 5mm thick, beige to pink in alcohol (Figure 3A).

Spicules. Megascleres large tylostyles with blunt point 520-797-930 × 15-18-20 × 18-20-23 μ m, small tylostyles with blunt point 250-320-410 × 10-12-18 × 13-14-18 μ m; microscleres selenasters 85-90-98 × 70-73-80 μ m, spherasters 15-19-25 μ m, stout spirasters with two or three contortions and acanthose spines spirally placed on shaft 8-11-18 × 3-4.5-5 μ m (Fig. 3)

Skeleton. As description of genus with addition that spirasters form a layer over and amidst the selenaster cortex and are also prevalent in choanosomal tissue. Spherasters amidst selenaster cortex and dispersed in choanosome.

Typelocality Sagami Bay, Eastern Japan, presently not recorded from any other locality.

On rock substrate in deep temperate waters.

Originally described by Tanita and Hoshino (1989) as Geodinella anthosigma. Geodinella is no longer a valid genus. Geodinella anthosigma should be transferred to the genus Placospongia based on the external morphology with the characteristic cortical plates and the presence of selenasters, tylostyles and spherasters. Placospongia anthosigma is distinguished from the other Indo-Pacific Placospongia spp. by the presence of contorted, spirally ornamented spirasters referred to by Tanita and Hoshino (1989) as ‘anthosigma’ and the small class of tylostyles with blunt points.

Holotype. “South Sea”: BMNH R1228 - 86g - Bk.1390 (slide), R1275 - PE01 - Bk1390 (slide).

Vosmaer & Vernhout (1902), Siboga expedition: RMNH POR. 755; RMNH POR. 754; RMNH POR. 744. Other material: RMNH POR. 4484, RMNH POR. 3943, RMNH POR. 3944, RMNH POR. 4485, RMNH POR. 3945, RMNH POR. 3946, RMNH POR. 3947, RMNH POR. 3948, RMNH POR. 3949, RMNH POR. 3950; RMNH POR. 3951, RMNH POR. 3952, RMNH POR. 3953, RMNH POR. 3954, RMNH POR. 3955, RMNH POR. 4482, RMNH POR. 3956, RMNH POR. 3957, RMNH POR. 4483, RMNH POR. 3958; ZMA Por. 8813ZMA Por. 09578; ZMA Por. 11367, ZMA Por. 16584, ZMA Por. 10727, ZMA Por. 1818, ZMA Por. 10481, ZMA Por. 20735; ZMA POR.9189. (See Table 2 for full details per specimen)

Reviewed material is encrusting and/or branching. External morphology follows the description of the genus. Color of live specimens can be purple brown, chocolate brown, milk coffee brown, orange brown, orange, cream, or white (Fig. 1, 2). Color of choanosome is pale beige. After preservation in ethanol specimens retain some color of the live coloration.

Spicules. Holotype slide with spicules R1228-86g-Bk.1390 (BMNH) and slide with thick section R1275-PE01-Bk1390 (BMNH) (Fig. 4): megascleres large straight tylostyles with blunt ends 500-7 10-820 × 10-13-15 × 10-15-18 μm, small straight tylostyles with sharp ends 140-317-450 × 5-8-25 × 8-9-13 μm; microscleres selenasters 80-90-98 μm, streptasters with varying number of (spined) rays (5-10) with bifurcating endings or tufts 23-34-43 × 8-15 μm, acantho microrhabds 8-12-18 × 1-2.5 μm, spherasters absent. The range within the examined material (Table 1 & Fig. 5): megascleres large tylostyles 540-990 × 8-18 × 10-18 μ m, small tylostyles 175-550 × 3-10 × 3-13 μ m; microscleres selenasters 50-85 × 35-70 μ m, streptasters 15-48 × 5-18 μ m, acanthose microrhabds 5-18 × 1-2.5 μ m, spherasters absent.

Skeleton. As description of genus with addition that microrhabds form a layer over and amidst the selenaster cortex and are also prevalent in choanosomal tissue. Spirasters scattered in choanosome.

East African coast to eastern Indonesia (Fig. 9, Table 2). Originally described from the ‘South Sea’, presumably the South Pacific Ocean. This has been interpreted by some (Rützler 2002, van Soest et al. 2011) to be Palau or Vanuatu, but this remains speculative. Based on the reviewed material and literature the minimal distribution is from Madagascar (Lévi 1956), to the Seychelles, and across Indonesia to the Aru Islands (Table 2). Distribution may extend further East.

Depth 0–45m. In Indonesia rarely found in reef environment, but high abundance in marine lakes. Possibly higher prevalence in reefs in Eastern Africa, based on the ZMA Por. collection from the Seychelles and the publication from Madagascar (Lévi 1956).

The Bowerbank description from 1858 should be considered as the original description of ‘Geodia carinata’, now accepted as Placospongia carinata, with plates XXV fig. 19 and XXVI fig. 10 representing the streptasters (“arborescent elongo-subsphero-stella”). Subsequently in 1874 Bowerbank published a more extensive description of “Geodia carinata” including a drawing of the streptasters (fig. 3, p.299) and spined microrhabds (“minute multiangulated cylindrical retentive spicula”, fig. 2, p.299) that he described as characteristic of the species. In neither publication registration numbers were provided, however. The habitus drawing in fig. 5, p.299 of Bowerbank publication in 1874 is identical to the specimen BMNH95.6.7.1 that I received from the BMNH after requesting the holotype for Placospongia carinata. In addition, I received the slides of spicules (codes: R1228, 86g, Bk.1390) and of the thick cut (codes: R1275, PE01, Bk1390) that were labeled to belong to the holotype (Fig. 5). Upon inspection I discovered that the specimen BMNH 95.6.7.1 is in fact a Placospongia melobesioides, while the two slides do indeed represent Placospongia carinata containing the characteristic streptasters with bifurcating endings and the microrhabds as indicated in the Bowerbank images and in the images taken from these slides in Fig. 5. The slides clearly do not come from the specimen BMNH 95.6.7.1. In the 16 years between Bowerbank’s 1858 and 1874 publications, I fear that there has been some exchange or misinterpretation of the labels of the specimens resulting in the incorrect assignment of specimen BMNH 95.6.7.1 to the slides and as the holotype of Placospongia carinata. This specimen BMNH 95.6.7.1, furthermore, has two labels attached to it: one with “Geodia carinata”, and one with “Placospongia melobesioides”. According to Bowerbank (1874) three specimens had been reviewed for his manuscript: one received from his friend Mr. Thos. Ingall in 1854, one placed by Dr. Baird from the coral to the sponge collection in the BMNH, and one specimen purchased by Bowerbank in 1864. The first mentioned specimen is presumably the holotype, but as this specimen has not been located, I propose to designate the slides R1228-86g-Bk.1390 and R1275-PE01-Bk1390 as representing the holotype of Placospongia carinata.

Holotype. BMNH 52.4.1.14, Indonesia, Borneo island.

Vosmaer & Vernhout (1902), Siboga expedition: RMNH POR. 756, RMNH POR. 761, RMNH POR. 758, RMNH POR. 757, RMNH POR. 760, RMNH POR. 759. Other material:: RMNH POR. 4497, RMNH POR. 4496, RMNH POR. 4495, RMNH POR. 4114, RMNH POR. 3978, RMNH POR. 3977, RMNH POR. 3976, RMNH POR. 3942, RMNH POR. 3941, RMNH POR. 3940, RMNH POR. 3939, RMNH POR. 3938, RMNH POR. 3937, RMNH POR. 3935, RMNH POR. 3934, RMNH POR. 3933, RMNH POR. 3932, RMNH POR. 3177, RMNH POR. 3166, RMNH POR. 3154, RMNH POR. 2464, RMNH POR. 2463, ZMA Por. 13097, ZMA Por. 10459 (See Table 3 for full details per specimen)

Holotype BMNH 52.4.1.14 dry, chalky white angular branches, hard. Other examined material encrusting to branching, hard, thicker specimens slightly compressible. External morphology follows the description of the genus. Size ranging between 5-50 cm, though encrusting specimens may be larger growing within crevices. Ectosome color in life ranging from purple, dark black brown, chocolate brown, orange brown to light beige (Fig. 1, 2). Choanosome pale beige. After preservation color of ectosome is similar to live color.

Spicules. Holotype BMNH 52.4.1.14 (Fig. 6): Megascleres large straight tylostyles with blunt ends 670-880-1010 × 10-13-18 × 10-16-20 μm, small concave to straight tylostyles with sharp ends 205-293-420 × 5-10-13 × 5-10-13 μm. Microscleres selenasters 58-63-68 × 45-52-68 μm, spherasters 15-17-18 μm (five measurements, not abundant), spherules 1-2-3 μ m. The range within the examined material (Table 1): large tylostyles 460-1040 × 5-16 × 8-18 μ m, small tylostyles 190-470 × 3-13 × 3-15 μ m, selenasters 45-83 × 30-65 μ m, spherules 1-3 μ m, spherasters only found in singles in some individuals 15-20 μ m. Streptasters and microrhabds absent.

Skeleton. As description of genus with addition of sporadic spherasters lodged amidst selenasters in cortex and high abundance of spherules in choanosome and cortex.

Depth: 0-45m. Reefs, rocky shores, reefflats, mangroves, and marine lakes.

Type locality: Borneo. Distribution from Seychelles to Micronesia (Fig. 9, Table 3). Possibly further east to Central Pacific.

In the original description by Gray (1867) there is no mention of two size classes of tylostyles. I reexamined the original slide and conclude that the holotype does contain two size classes of tylostyles. The Systema Porifera indicates that the holotype has two size classes, the large 720-963-1200 × 13-14.1-19 μm and the small 350-438.8-560 × 8-9.1-10.5 μm, based on 10 measurements per spicule type (Rützler 2002). These measurements deviate from the holotype measurements in the present study that were based on 25 measurements per spicule type (670-880-1010 × 10-13-18 μm and 205-293-420 × 5-10-13 μm respectively), and also deviate from the range of sizes within the examined material of this study (Table 1). There is great variation in tylostyle length and spherasters are only sporadically present, often absent.

Holotype. ZMB 3204, Indonesia, Moluccas, Ternate.

Vosmaerand & Vernhout (1902), Siboga expedition: RMNH POR. 753, RMNH POR. 751, RMNH POR. 745, RMNH POR. 742. Other material: RMNH POR. 4494, RMNH POR. 4493, RMNH, POR. 4492, RMNH POR. 4491, RMNH POR. 4490, RMNH POR. 4489, RMNH POR. 4113, RMNH POR. 4112, RMNH, POR. 3979, RMNH POR. 3975, RMNH POR. 3974, RMNH POR. 3973, RMNH POR. 3972, RMNH POR. 3971, RMNH POR. 3970, RMNH POR. 3969, RMNH POR. 3968, RMNH POR. 3967, RMNH POR. 3966, RMNH POR. 3965, RMNH POR. 3964, RMNH POR. 3963, RMNH POR. 3962, RMNH POR. 3961, RMNH POR. 3960, RMNH POR. 3959, RMNH, POR. 3163, RMNH POR. 3158, RMNH POR. 3157, RMNH POR. 3155, RMNH POR. 3148, ZMA Por. 10495, ZMA Por. 896 (See Table 4 for full details per specimen)

Holotype ZMB 3204 encrusting, size 5 × 2.5 cm and thickness 1–5 mm (as described by Thiele, now very small fragment), white after preservation in alcohol. The majority of the reviewed material is encrusting with a thickness of 4-10mm, but branching specimens also occur. External morphology follows the description of the genus. Color of the ectosome can be red, orange, brown orange, dark brown, chocolate brown, milk coffee brown, cream, or white (Fig. 1, 2). Color of choanosome is pale beige. After preservation in ethanol color is similar to live specimens, but lighter shade.

Spicules. Holotype ZMB 3204 (Fig. 6) Megascleres large straight tylostyles with blunt/rounded point 355-672-940 × 7.5-12-17.5 × 7.5-16-20 μm, small straight tylostyles with sharp point 165-226-275 × 2.5-6-7.5 × 2.5-8-10 μm; microscleres selenasters 55-70-75 × 42.5-55-72.5 μm, spherasters (abundant) 20-25-30 μm, streptasters typically with well developed axis and with 4-9 rays with hastate tips, rays are smooth or can be spined, but do not have bifurcations of the tips 15-24-32.5 × 2.5-8-12.5 μm; acanthose microrhabs with straight or zig-zag axis 5-7-10 × <2.5 μ m.The range within the examined material (Table 1): large tylostyles 460-1250 × 8-23 × 10-25 μ m, small tylostyles 120-430 × 3-15 × 2-15 μ m, selenasters 50-85 × 22-73 μ m, spherasters 13-30 μ m, streptasters 15-35 × 2-15 μ m, rays 5-18 × 1-2.5 μ m.

Skeleton. As description of genus with addition that microrhabds form a layer over and amidst the selenaster cortex and are also prevalent in choanosomal tissue. Streptasters scattered in choanosome. Spherasters amidst selenasters in cortex and scattered in choanosome.

East African coast to eastern Indonesia (Fig. 9, Table 4). Possibly further east to Central Pacific. Pulitzer-Finali (1993) identified a ‘P. carinata’ from East Africa (Mombasa) that fits the description of Placospongia mixta based on the length of the tylostyles (up to 1200 μ m) and the presence of spherasters, but no Placospongia mixta specimens were observed in the Seychelles material deposited at ZMA.

Depth 0–45m. Common in reefs, also occurs in marine lakes.

In 1900 Thiele described a new species named Placospongia mixta, which was originally identified as Placospongia melobesioides by Kieschnick (1896). The specific epithet mixta was given because the specimen contained a mixture of spicules: both spirasters like Placospongia carinata as well as large spherasters like Placospongia intermedia and Placospongia melobesioides, which are absent in Placospongia carinata. In 1902 Vosmaer & Vernhout decided that Placospongia mixta was a junior synonym of Placospongia carinata, because they saw no distinction between the different shapes of streptasters and stated that spherasters are never very abundant – in some ‘exceedingly rare and in some we failed to find them at all’ – and could therefore not be seen as a distinguishing character. The specimens that were studied by Vosmaer and Vernhout (1902) were collected in Indonesia during the Siboga Expedition (1899-1900) and are housed in the collection of the Naturalis Biodiversity Center (Leiden, The Netherlands). In the present study these specimens were reexamined. After inspection, the specimens labeled ‘Placospongia carinata’ could be clearly and consistently divided into two species: Placospongia carinata without spherasters, with streptasters displaying bifurcating tips, and tylostyles up to 980 μ m, and Placospongia mixta with abundant spherasters, with streptasters displaying hastate tips, and tylostyles up to 1250 μ m. In none of the specimens of Vosmaer and Vernhout (1902), nor of the other specimens reviewed for this study was there a mixture of the two types of streptasters. These two species also show molecular distinction in both mitochondrial and nuclear markers (Fig. 10, 11, Table 6, 7).

RMNH POR. 4486, Indonesia, East Kalimantan province, Maratua island, Buli Halo anchialine pool, 02°11'16.4"N, 118°37'06.4"E, 0–1m. depth, xi.2008, coll. N.K. Santodomingo & Estradivari, #BER128/mol1147. Paratypes. RMNH POR. 4487, Indonesia, East Kalimantan province, Maratua island, Buli Halo anchialine pool, 02°11'16.4"N, 118°37'06.4"E, 0–1m. depth, xi.2008, coll. N. K. Santodomingo & Estradivari; RMNH POR. 4488, Indonesia, East Kalimantan province, Maratua island, Buli Halo anchialine pool, 02°11'16.4"N, 118°37'06.4"E, 0–1m. depth, xi.2008, coll. N. K. Santodomingo & Estradivari, #BER128/1156.

Holotype and paratypes are branching and encrusting, size 8cm in length. Total size of specimens in situ is hard to establish as parts of the body may be encrusting within cracks. Alcohol preserved and live specimens are hard but slightly compressible. The surface is made up with typical Placospongia cortical plates separated by contractible grooves which form a network on the surface. Oscules are present in the grooves. Live color of holotype was dark brown, the paratypes were orange, and these colors were mostly retained after alcohol preservation (Fig. 8A).

Spicules. Holotype (Fig. 8) megascleres large straight tylostyles with blunt point 430-605.5-660 × 13-15.5-20 × 13-18.1-23 μm, small straight tylostyles with sharp point 240-261.3-290 × 5-7.2-8 × 5-8.8-10 μm; microscleres selenasters 80-84.8-90 × 60-67.3-75 μm, acanthose microrhabds 8-12.3-18 × 2.5-2.7-3.5 μm. Range of the paratypes (Table 1) large straight tylostyles with blunt point 430-760 × 13-20 × 15-23 μm, small straight tylostyles with sharp point 190-380 × 5-13 × 8-15 μm, microscleres selenasters 63-93 × 58-75 μ m, acanthose microrhabds 5-20 × 2.5-3.5 μ m.

Skeleton. The cortical plates consist of densely packed selenasters, microrhabds form a layer over and amidst this selenaster cortex and are also prevalent in choanosomal tissue. Developmental stages of selenasters occur throughout the choanosome. Tylostyle tracts support the margins of the cortical plates in radial tracts from the centre core (consisting of densely packed selenaster) to the cortical plates. The sharp ends of the smaller tylostyles can be projected beyond the cortex surface.

Presently only recorded from Buli Halo anchialine pool on Maratua island, Berau, East Kalimantan, Indonesia (Fig. 9). For a full description of the pool, see Becking et al. (2011)

Depth 0–2m. occurs in anchialine pool, can be exposed to air during low tide and can tolerate great fluctuations in salinity (from 24 to 33 ‰).

Named in honor of Nadiezhda K. Santodomingo, the collector of the types, for her years of tireless work in marine science including anchialine research.

Placospongia santodomingoae sp. n. is similar to Placospongia carinata, yet lacks streptasters and has shorter tylostyles. Placospongia santodomingoae sp. n. likewise differs from Placospongia mixta by the absence of streptasters as well as the absence of spherasters. Placospongia santodomingoae sp. n. differs from Placospongia anthosigma by the absence of anthosigma, and by having hastate endings of the smaller tylostyles.

Holotype. BMNH 02.11.16.1, South Africa, East London Coast, 33°06'30"S, 028°11'E.

Spicules. Megascleres styles, oxea; microscleres sterrasters, chiasters

This species was originally described as ‘Placospongia labyrinthica’, butdoes not have the characteristic cortical plates of Placospongia. The specimen furthermore has sieve pores, sterrasters with star-like plates, euasters, styles and oxea characteristic of the Geodiidae. In the original description, Kirkpatrick (1903) stated “the presence of chiasters is so exceptional that I thought at first that I had to deal with a geodine sponges, but there were no triaenes to be found” and as a result placed this species in the Placospongia rather than Geodia. Genus transfer to Geodia is, however, required as suggested on the World Porifera Database (van Soest et al. 2011).