Cornulum johnsoni ( De Laubenfels, 1934 )

Van, Rob W. M., 2017, Sponges of the Guyana Shelf, Zootaxa 1, pp. 1-225 : 130-131

Cornulum johnsoni ( De Laubenfels, 1934)

Figures 80 a–e

Coelosphaerella johnsoni De Laubenfels, 1934: 21 .

Cornulum johnsoni ; Van Soest 1984: 75; Van Soest et al. 1994: 186; Hooper 2002b: 419; Rützler et al. 2014: 56, fig. 31.

Material examined. RMNH 10545 , Suriname, ‘ Snellius O.C.P.S. ’ Guyana Shelf Expedition, station B23A, 7.297°N 55.3883°W, depth 99–101 m, Van Veen grab, 27 April 1966 .

Examined for comparison. Slide of holotype of Coelosphaerella johnsoni , USNM 22364, First Johnson- Smithsonian Deep Sea Expedition stat. 81, coll. 26 February 1933, depth 200–400 fathoms.

Description. Tiny, elongately fistular sponge enveloping a piece of dead black coral. Size less than 3x 1 mm. Surface provided with several tiny projections less than 1 mm in height. Color (alcohol) white. Consistency fragile.

Skeleton. ( Fig. 80 a) Tangential intercrossing tylotes cover the organic skin of the fistular body. No trace of choanosomal tracts was observed.

Spicules. ( Figs 80 b–e) Tylotes, palmate isochelae, toxas.

Tylotes ( Figs 80 b,b1), with strongly microspined apices, shaft curved, 225– 236 –249 x 4.5– 6.2 –7 µm.

Palmate isochelae ( Fig. 80 c), in majority twisted, 15.5– 17.1 –19 µm.

Toxas (rare), in two size classes, (1) larger ( Fig. 80 d) (n=2) 123–148 µm, and (2) smaller ( Fig. 80 e) (n=3) 18–54 µm.

Distribution and ecology. Guyana Shelf, Puerto Rican Deep, soft bottom and shallow cryptic habitats, in a wide depth range, 1–720 m ( Guyana Shelf 99–101 m).

Remarks. Due to the scanty material and the toxas being relatively rare (these were not found on the SEM stub, only in the slide for light microscopy) the illustration is rather deficient. Nevertheless the toxas appeared to occur in larger and smaller sizes conforming to those of the type material from Puerto Rico . The type is much bigger (14 mm in diameter), but the skeleton and the spicules of the present specimens are almost the same. De Laubenfels (1934) gives the size of the tylotes as 9 by 420 µm, which is likely a misprint for 9 by 240 µm (observed in the type slide and in the present specimen), because in his remarks below the description of C. johnsoni he cites the Philippine species Coelosphaera (= Cornulum ) toxifera Wilson, 1925 as having ‘much larger megascleres’ at 16 by 360 µm.

Rützler et al. ’s (2014) images and spicule measurements of a specimen from Belize are also virtually identical to the present specimen.

Figures

FIGURE 80. Cornulum johnsoni (De Laubenfels, 1934), a, light microscopic image of the surface skeleton, b – c, SEM images of spicules, b, microspined tylote, b 1, details of b, c, twisted palmate isochela, d – e, light microscopic images of toxas (outlines artificially enhanced), d, large toxa, e, small toxa.