Pyloderma tropicale, Van, Rob W. M., 2017

Van, Rob W. M., 2017, Sponges of the Guyana Shelf, Zootaxa 1, pp. 1-225 : 139

Pyloderma tropicale sp. nov.

Figures 86 a–d

Material examined. Holotype RMNH Por. 10513, Suriname, ‘ Snellius O.C.P.S. ’ Guyana Shelf Expedition, station F46, 6.312°N 56.57°W, depth 25–29 m, bottom sand, 7 May 1966 .

Description. The holotype ( Fig. 86 a) is fragmented, but assumed to have been originally a single specimen of 10 x 5 cm in lateral expansion, less than 1 cm thick. The fragments are bladder-like with an irregular undulating semitransparent surface sheet with many tiny fistules. The interior is cavernous, with few skeletal structures. Color beige-brown in alcohol. Consistency soft but elastic.

Skeleton. ( Fig. 86 b) Loose choanosomal tracts of 100–150 µm diameter rise up from the substratum and fan out to carry the surface membrane.

Spicules. ( Figs 86 c–d) Oxeas only.

Oxeas, straight, equidiametrical, with lance-shaped, slightly swollen sharply pointed apices; in shape and position in the skeleton there appear to be two (largely) overlapping categories, (1) shorter and thicker ( Figs 86 c,c1), 134– 166 –189 x 6 – 7.3 –9 µm, and (2) longer and thinner ( Figs 86 d,d1), 156– 183 –213 x 2.5– 3.4 –4.5 µm.

Distribution and ecology. Guyana Shelf, on sandy bottom at 25–29 m depth.

Etymology. The name reflects the unusual occurrence of a Pyloderma species in tropical waters.

Remarks. No other sponges with these peculiar lance-shaped oxeas are known from the Central West Atlantic . Assignment of this unusual species to the genus Pyloderma is tentative, but presently the best fit. It can only be tested by comparison of additional material and/or molecular analyses to resolve this systematic hypothesis. The type species of Pyloderma , Southern Ocean Halichondria latrunculioides Ridley & Dendy, 1886 is pear-shaped and has much larger oxeas (up to 1200 µm), but the form of the latter is also lance-shaped like in the present species (cf. Van Soest 2002a). The only other species of Pyloderma , the New Zealand P. demonstrans Dendy, 1924 has chelae and sigmas, for which reason the (presently unaccepted) genus Manawa Bergquist & Fromont, 1988 was erected. If the present species indeed belongs to Pyloderma , then resurrection of Manawa might be considered.

Figures

FIGURE 86. Pyloderma tropicale sp. nov., a, habitus of holotype RMNH Por. 10513 (scale bar = 1 cm), b, light microscopic image of the surface membrane, c – d, SEM images of the spicules, c, short and fat oxea, c 1, details of c, d, long and thin oxea, d 1, details of d.