Agelas schmidtii Wilson, 1902

Van, Rob W. M., 2017, Sponges of the Guyana Shelf, Zootaxa 1, pp. 1-225 : 117

Agelas schmidtii Wilson, 1902

Figures 71 a–b

Agelas schmidtii Wilson, 1902: 398 ; Van Soest & Stentoft 1988: 102, fig. 50; Parra et al. 2014: 329, fig. 12. Agelas sp. sensu Johnson 1971: 109, fig. 12.

Material examined. RMNH Por. 9794, French Guyana, ‘Luymes’ Guyana Shelf Expedition, station 14, 6.7333°N 52.75°W, depth 76 m, bottom muddy calcareous sand, 26 August 1970 .

Description. ( Figs 71 a,a1) Tubular-repent sponges, consisting of thin-walled anastomosed branches issuing from a broader presumably buried basal part. Surface smooth but ‘pitted’ by thin-membranous patches, which may represent shrunken oscules. Color pale yellow-orange (in alcohol). Length of branches 7–12 cm, diameter 1.5 cm, wall of tubes about 3–4 mm in thickness. Consistency toughly compressible, not easily damaged.

Skeleton. A regular tightly meshed anisotropic reticulation of spongin fibers, 50–60 µm in diameter. The ascending fibers may be cored, sometimes heavily, with up to 6 spicules in diameter, the connecting fibres are usually free of coring. Both fibers are echinated profusedly.

Spicules. Verticillated acanthostyles ( Figs 71 b–b2), incipient stages ( Fig. 71 b3) smooth.

Acanthostyles, predominantly short and fat, the shorter spicules with prominent spines in well-separated verticils, the larger and thicker occasionally show reduction of spines and verticils, 87– 162 –218 x 7 – 15.1 –20 µm, with 8– 12.2 –14 verticils of spines.

Distribution and ecology. Guyana Shelf, Virgin Islands, furthermore throughout the Caribbean, NE Brazil, on hard and muddy bottoms, 1–144 m depth ( Guyana Shelf, 76 m).

Remarks. The present specimens conform in all important aspects to the description of Wilson (1902), and the revision of the species by Parra et al. (2014), including the deep-water material reported by Van Soest & Stentoft (1988) from Barbados. A difference with all these descriptions is the average thickness of the acanthostyles (12.2 µm), which exceeds all previous measurements (6–8 µm). However, the thickest spicules in the present material (14 µm) are close to the maximum given by Parra et al. (1914) (13 µm). Possibly, there are environmental influences (e.g. silica content) on the development of the spicules.

Figures

FIGURE 71. Agelas schmidtii Wilson, 1902, a, habit of RMNH Por. 9794 (scale bar = 1 cm), a 1, detail of hollow base (scale bar = 1 cm), b – b 3, SEM images of spicules, b, slightly curved fullgrown verticillated styles, b 1, detail of b, b 2, large almost smooth style, b 3, smooth juvenile stage showing annular swellings as incipient verticils.