Amphinolana claudelevii, Rützler & Hooper, 2000

Rützler, Klaus & Hooper, John N. A., 2000, Two new genera of hadromerid sponges (Porifera, Demospongiae), Zoosystema 22 (2), pp. 337-344 : 339-342

Amphinolana claudelevii n. sp.

( Figs 1-3 )

HOLOTYPE. — Heron Island. North Point, Capricorn Group , Queensland, Australia , 23 °26.56’S, 151∞58.75’ E. Reef crest on lee side of bay, intertidal, from lower surface of a coral boulder, 14.IX.1997, John A. Kennedy & Susan List-Hermitage ( USNM 51356 ).

PARATYPE. — QM G 31 3420 (part of holotype) ; same data as holotype .

ETYMOLOGY. —Named after Professor Claude Lévi, Paris, eminent spongiologist.

DISTRIBUTION. — Tropical, intertidal, cryptic reef sponge; only known from the type locality on the Great Barrier Reef , Australia .

DESCRIPTION

Morphology

A thin (0.8-1.5 mm) crust covering about 10 cm 2. The appearance in the field was described as “gelatinous-grey with blue streaks on microconulous surface”; on a photograph taken fresh after collection the sponge looked slimy black. In alcohol the consistency is leathery, the color is a light tan. The specimen photographed ( Fig.1A ) is the alcohol-preserved holotype (USNM portion) with pore grooves closed. Under the stereo microscope, the surface shows characteristic polygonal fields corresponding to cortical plates of amphiasters separated by aquiferous grooves devoid of cortical spicules. The grooves are marked by a slight elevation (0.2-0.6 mm high) of the abutting plate margins; in life they open to at least 0.5 mm and may have appeared as “blue streaks”, as reported by the collectors.

Tracts of spongin-bound tylostyles (100-200 µ m wide) radiate from the substrate toward the surface where they penetrate in places supporting the cortical plates on either side of the grooves ( Fig. 1B ). The cortex consists of a dense, 60- 100 µm thick top layer of tightly spongincemented amphinolasters, followed by a 250-300 µm fibrous zone (700 µm in the region of a groove), striation parallel to the sponge surface, devoid of spicules but rich in spongin and cells, presumably actinocytes and spongocytes. The choanosome is a 400-1100 µm thick and includes most cellular components, aquiferous canals, and abundant but scattered amphinolasters (spaced on average 25 µm apart) and much rarer spirasters ( Figs 2A ; 3G ). A sponginrich base layer (25-50 µm) attaches the sponge crust to the substratum.

The amphinolasters ( Figs 2A ; 3 ) start development as straight, slender, spiny rhabds with longer spines toward the ends of the shaft. Mature spicules have smooth or lumpy shafts (lumps are poorly developed spines) and two heads densely covered by bulbous or mammiform spines fused at the base. In transmitted light, the shafts show distinct axial canals; no such structures are seen in the spines. Most spines in fully developed amphinolasters are mucronate, some are connected by delicate siliceous ridges or bear thin secondary spines ( Fig. 3A, F, G ), possibly stages in the deposition of silica. Tylostyles are long, slender, gradually tapering toward the point, with inconspicuous oval heads; some heads are subterminal or show one or more constrictions ( Fig. 2B ).

Spicule measurements

Measurements are ranges; means and standard errors are in parentheses. Tylostyles, length × width: 450-700 (578.0 ± 24.2) × 5.0-7.5 (6.3 ± 0.1) µm; tylostyle heads, length × width: 8.8- 15.0 (12.0 ± 0.7) × 6.3-10.0 (7.8 ± 0.3) µm. Mature amphinolasters, length × width (head) × width (shaft): 27.5-42.5 (39.0 ± 1.4) × 15.0-20.0 (16.8 ± 0.8) × 6.3-15.0 (8.5 ± 0.8) µm; immature amphinolasters (rays free, not yet cemented along their lengths), length × width (head) × width (shaft): 25.0-33.8 (30.9±1.1) × 5.0-12.5 (8.3 ± 0.9) × 1.3-5.0 (3.0 ± 0.4) µm. Spirasters (bent or double-bent spiny rhabds), length × width (n = 5): 8.8-12.5 × 1.0 µm.

REMARKS

Amphinolana claudelevii stands out among the species in the family Placospongiidae by the morphology and development of its cortical spicules and the simple complement of accessory microscleres which are absent in the cortex and canal walls. Five species are recognized in the only other genus, Placospongia , which share oval or bean-shaped cortical selenasters and are distinguished on the basis of their accessory microscleres (spirasters, spiny microrhabds, spherasters, spherules) and their location (cortex, canal walls), not by differences in cortical microscleres. These species include the genotype, P. melobesioides Gray, 1867 , P. carinata (Bowerbank, 1859) (including P. intermedia Sollas, 1888 and P. mixta Thiele, 1900 ), P. cristata Boury-Esnault, 1973 , P. decorticans (Hanitsch, 1895) (incl. P. graeffei von Lendenfeld, 1894 ) and P. labyrinthica Kirkpatrick, 1904 and are described in Vosmaer & Vernhout (1902), Kirkpatrick (1903), and Boury-Esnault (1973). Only P. decorticans has distinctive selenasters, pronouncedly bean-shaped instead of ovoid, but the structure and development of these spicules are identical to their counterparts in the other species of Placospongia .

Curiosity about the nature of the selenasters dates back to the earliest reports on Placospongia . Gray (1867), author of the genus, likened the “siliceous globules” of these sponges to the cortical sterrasters of the genus Geodia Lamarck, 1815 . Several subsequent workers followed this view and assumed a close relationship between these two sponge groups until Keller (1891: 298) determined that the “siliceous balls” of Placospongia derive from spirasters while those of Geodia develop from euasters. Apparently unaware of these discussions, Hanitsch (1895: 214), describing the new sponge Physcaphora (= Placospongia ) decorticans , named the “sausageshaped” microscleres “selenasters”. He points out that they resemble sterrasters in structure and development but with the principal difference that in sterrasters the rays start from a point, whereas in the selenasters they originate from a more or less twisted rod. In a monograph of Placospongia, Vosmaer & Vernhout (1902: 6) discuss the earlier accounts but use the term “sterrospira” instead of selenaster; they do however reject yet another term, “pseudosterraster”, as confusing. During a recent review of spicule terminology (in Boury-Esnault & Rützler 1997: 46), selenaster is accepted as “a special type of spiraster approaching the shape of a sterraster...”.

The architectural plan and development of the selenaster described in detail by Vosmaer & Vernhout (1902) is now confirmed by scanning electron microscopy (Rützler & Macintyre 1978; Gonzáles-Farías 1989). It is based on circular arching of the original axis (a spiraster-like spiny microrhabd which is lost during development) and deposition of spines and cement between them toward a point of fusion, which results in an ovoid or bean-shaped spicule. In amphinolasters on the other hand, the axis remains straight and exposed (as shaft, with axial canal remaining visible) and spines extend radially from two distant points, the swollen extremities of a spiny microrhabd. Furthermore, spines in mature selenasters become cemented almost beyond recognition and the tips are connected by an intricate network of siliceous ridges which is only interrupted by a hilum, a circular depression believed to mark the position of the scleroblast nucleus (Sollas 1888). Spines in mature amphinolasters remain discreet and retain their mammiform appearance, and there is no hilum. Selenasters are quite large in all species, ranging from about 50 µm (larger diameter) in P. cristata to more than 150 µm in P. labyrinthica , whereas amphinolasters average only 39 µm in length. Purple pigmentation described for selenasters of some specimens of Placospongia species (Vosmaer & Vernhout 1902) was not observed in amphinolasters of the present material.

The discrepancy between consistency and color observations made on the live sponge (gelatinous grey, slimy black on photograph) and appearance of the same specimen preserved in alcohol (leathery firm, light tan) could be attributed to a coating by cyanophytes or sciaphilous algae on the cortex which fell off during fixation because no pigment cells or granules can be seen in sections of the ectosome. A similar algal coating was noted on Placospongia decorticans (Hanitsch, 1895) in an ecologically comparable situation, from the lower surface of an intertidal rock, in the Adriatic Sea (Rützler 1965: 17).

Figures

FIG. 1. — Amphinolana claudelevii n. gen. n. sp.; A, photomacrograph of surface with cortical plates (alcohol-preserved specimen); B, ground thick section, perpendicular to surface, showing cortex and aquiferous groove (contracted) supported by strands of tylostyles. Scale bars: A, 5 mm; B, 50 µm.

FIG. 2.— Amphinolana claudelevii n. gen.n. sp.; A, part of tylostyle with microscleres;B, modifications in tylostyle heads.Scale bars:10 µm.

FIG. 3. — Amphinolana claudelevii n. gen. n. sp.; A-E, amphinolasters in different stages of development; F, spiraster and head of amphinolaster; G, spirasters and enlarged details of amphinolasters. Scale bars: 10 µm.