Dragmaxia undata Alvarez, Van Soest & Rützler, 1998

Van, Rob W. M., 2017, Sponges of the Guyana Shelf, Zootaxa 1, pp. 1-225 : 50-51

Dragmaxia undata Alvarez, Van Soest & Rützler, 1998

Figures 32 a–c

Dragmaxia undata Alvarez, Van Soest & Rützler, 1998: 26 , fig. 15; Rützler et al. 2014: 71 .

Material examined. RMNH Por. 9821, Suriname, ‘ Snellius O.C.P.S. ’ Guyana Shelf Expedition, station E66, 7.1°N 56.1783°W, depth 65 m, Agassiz trawl, 13 May 1966 .

Description. Erect digitations ( Fig. 32 a) on a cushion-shaped basis attached to a dead shell. Height of specimen 4 cm, dimensions of the two digitations 1–1.5 cm high and 0.5 cm diameter. Surface irregular, encrusted with bryozoans, microhispid, semitransparent, whitish-yellowish in color (alcohol preserved). Consistency firm.

Skeleton. This consists of largely confused single styles, but vague tracts of spicules are directed upwards into the digitations. Styles partially penetrate the surface. No visible spongin. Many open spaces. Straight, or more frequently, wavy trichodragmas are numerous between the styles.

Spicules. ( Figs 32 b–c) Styles, trichodragmas.

Styles ( Fig. 32 b,b1), slightly to strongly curved, seldom straight, more or less equidiametrical over much of their length, sharply pointed, 690– 893 – 1046 x 13 – 19.2 –26 µm.

Trichodragmas ( Figs 32 c,c1), curved and wavy, seldom straight, raphides provided at both ends with one or two hook-like spines ( Fig. 32 c1), 184– 220 –258 x 4 – 6.4 –9 µm.

Distribution and ecology. Guyana Shelf, Curaçao, Bonaire, Colombian Caribbean, Belize, in cryptic reef habitats and at greater depth on shelly slopes, at 0.5–65 m depth (previously down to 35 m).

Remarks. The present specimen differs in shape from the type material and from the Belize material, as these were basically encrusting. However, the digitate shape clearly developed from an encrusting base, so it may merely represent a more developed form in a habitat with less competition. Spicule shapes and sizes conform closely to the type material. The Belize material apparently had trichodragmas up to 600 µm, considerably longer than trichodragmas in the type material and the Guyana material.

Figures

FIGURE 32. Dragmaxia undata Alvarez, Van Soest & Rützler, 1998, a, habitus of RMNH Por. 9821 (scale bar = 1 cm), b – c, SEM images of spicules, b, style, b 1, details of b, c, raphides of trichodragma, c 1, details of raphide apices.