Paragrantia waguensis Hozawa , 1940

Van Soest, Rob W. M., Hoeksema, Bert W., Reimer, James D. & De Voogd, Nicole J., 2015, New records of the rare calcareous sponge Paragrantiawaguensis Hozawa, 1940, ZooKeys 546, pp. 1-20 : 4-9

Taxon classification Animalia Leucosolenida Grantiidae

Paragrantia waguensis Hozawa, 1940 Figs 1, 2, 3, 4, 5

Paragrantia waguensis Hôzawa, 1940: 40, pl. V figs 8-11, text-fig. 4; Burton 1963: 448, text-fig. 274 as named form of Scypha compressa (not: Spongia compressa Fabricius, 1780).

Grantia waguensis ; Van Soest et al. 2015 on-line.

Material.

Naturalis Biodiversity Center, reg. nr. RMNH Por. 9317 (five individuals), Japan, South Kuroshio ecoregion, Okinawa, Manza, approximately 26.5°N, 127.8°E, vertical rocky wall, 25-30 m, coll. B.W. Hoeksema, 10 August 2014; Naturalis Biodiversity Center, reg.nr. RMNH Por. 3901 (three individuals), Japan, South Kuroshio ecoregion, Okinawa, Onna village, approximately 26.5°N, 127.8°E, coral reef slope, 20-55 m, coll. J. Tanaka, 6 May 2006.

Syntype, 8 specimens (not seen) Tôhoku University Museum, reg.nr. TUMC 110908, Japan, Central Kuroshio ecoregion, Mie Prefecture, Wagu, approximately 34.25°N, 136.8°E, coll. S. Hôzawa, July 1933.

Description.

Cup-shaped or tubular specimens (Fig. 1 a–e), usually being a single rounded ‘person’ in life, but larger individuals may be somewhat elliptical, and occasionally consisting of two or three budded individuals. The cups or tubes have a narrow attachment to the substratum but there is no clear stalk. Outer surface pearly white and smooth, without any visible inhalant structures. The rim is pale purple in color and distinctly fringed. Algae or detritus may stick to the rim. Inside the cup, most specimens are likewise smooth and white, but one of the specimens is mottled greenish due to encrusting algae growing on its inner surface (Fig. 1d). A faint punctate inner surface pattern may be discernible in some individuals, representing the peculiar exhalant chambers characteristic for this species. Size of individuals may vary from 1 to 4 cm in height, 0.5-4 cm in diameter, thickness of the walls up to 1.5 mm. Consistency firm, somewhat flexible, but breakable under pressure. In preserved condition, the shape of the individuals alters notably: the specimens collapse and may become folded and compressed.

Aquiferous system. No histological slides were made, but the structure of the skeleton suggests it is syconoid (as was also the case in Hôzawa’s material). There is no evidence of branching choanocyte chambers. Subcortical lacunae are present, regularly distributed and apparently serving as inhalant reservoirs.

Skeleton of the walls. (Figs 2-4) In cross section from external side to inside: a fairly thick cortical skeleton of relatively large triactines (Fig. 2a), an articulate tubar skeleton (Fig. 3a) consisting of three or more rows of sagittal triactines with centrifugally directed unpaired actines, subsequently a layer of subatrial strongly sagittal triactines, and an atrial skeleton (Fig. 4 a–b) of tetractines and triactines, containing the three-dimensionally rounded atrial exhalant chambers (Fig. 4b) supported and covered by inwardly directed small butterfly-shaped tetractines (Figs 4 c–c 1) with peculiarly swollen and ornamented apical actines (see below). These small apopylar tetractines in addition to the normal atrial triactines (Fig. 4d) and tetractines (Fig. 4e) are so far unique among the Calcarea.

Skeleton of the fringe. (Fig. 5 a–b) The main support of the fringe consists of a palisade of long thick diactines tangentially covered outside and inside by sagittal triactines and tetractines differing morphologically from those of the walls.

Spicules. Cortical triactines, tubar triactines, subatrial triactines, atrial triactines, atrial tetractines, apopylar tetractines, diactines from the fringe, triactines from the fringe, tetractines from the fringe.

Cortical triactines (Fig. 2b), mostly slightly sagittal, with unpaired actines generally longer than paired actines, but not infrequently all actines are about the same length with the sagittal morphology only expressed by a wider angle between the paired actines; unpaired actines 48 –196.6– 315 × 6 –15.3– 24 µm, paired actines 40 –162.4– 242 × 9 –14.7– 23 µm.

Tubar triactines (Fig. 3b), sagittal, unpaired actines usually longer than paired actines, with paired actines often having a wide angle with the unpaired actines, frequently rather 'oxhorn shaped’, the ends curved slightly inwards; unpaired actines 93 –195.2– 270 × 8 –13.6– 21 µm, paired actines 92 –148.2– 241 × 9 –13.4– 21 µm.

Subatrial triactines (Fig. 3c), strongly sagittal, with paired actines wide angled, occasionally at right angles with the unpaired actines, but often not in the same plane, unpaired actines much longer than paired actines; unpaired actines 207 –242.3– 291 × 6 –8.3– 10 µm, paired actines 61 –85.0– 111 × 6 –8.4– 10 µm.

Atrial triactines (Fig. 4d), strongly sagittal, with unpaired actines longer than the paired actines, but differentiated from the subatrial triactines by longer paired actines; unpaired actines 150 –247.5– 354 × 8 –9.6– 11 µm, paired actines 114 –171.1– 261 × 7 –10.3– 12 µm.

Atrial tetractines (Fig. 4e), sagittal, with unpaired and paired actines not strongly different in length, but occasionally the paired actines are slightly longer, and apical actines conical; unpaired actines 42 –118.7– 226 × 7 –9.7– 10 µm, paired actines 105 –132.7– 171 × 7 –9.0– 10 µm, apical actines 30 –37.3– 63 × 6 –8.6– 12 µm.

Atrial exhalant chamber tetractines (apopylar tetractines) (Figs 4c, 4c1), butterfly-shaped, sagittal, with short conical unpaired actines, distinctly longer paired actines, and with the apical actines swollen and ornamented with irregular spines, curved slightly inwards, likened to ‘torches’ by Hôzawa (1940: 42); unpaired actines 14- 23.6 -39 × 3 –3.8– 5 µm, paired actines 27 –64.1– 78 × 3 –4.1– 5 µm; apical actines 13 –19.4– 24 × 5 –8.2– 10 µm.

Diactines (Fig. 5c) from the fringe, fusiform, sharply pointed, 360 –703.2– 990 × 12 –21.6– 29 µm.

Tetractines (Fig. 5d) from the fringe, strongly sagittal, unpaired actines longer than the paired actines, which are widely flaring, and apical actines conical, sharply pointed; unpaired actines 165 –284.8– 528 × 9 –10.6– 15 µm, paired actines 81 –167.6– 273 × 8 –10.3– 12 µm, apical actines 16 –39.3– 76 × 5 –7.2– 10 µm.

Triactines (Fig. 5e) from the fringe, strongly sagittal, with much longer unpaired actines than paired actines (similar to subatrial triactines), 156 –223.5– 279 × 6 –8.8– 10 µm, paired actines 63 –84.8– 105 × 7 –9.2– 10 µm.

Ecology.

No data were provided by Hôzawa, but the Okinawa specimens were from a steep reef slope at 20-55 m depth, growing among coralline and turf algae, and encrusting sponges.

Distribution.

Warm-temperate (Mie Prefecture) and subtropical (Okinawa) regions of Japan.