Oceanapia cf. stalagmitica ( Wiedenmayer, 1977 )

Van, Rob W. M., 2017, Sponges of the Guyana Shelf, Zootaxa 1, pp. 1-225 : 46-48

Oceanapia cf. stalagmitica ( Wiedenmayer, 1977)

Figures 29 a–g

Biminia stalagmitica Wiedenmayer, 1977: 124 , pl. 26 fig. 1, text-figs 133–134. Oceanapia stalagmitica ; Lehnert & Van Soest 1996: 78, figs 17, 32, 78–81.

Material examined. RMNH Por. 9736, Guyana, ‘Luymes’ Guyana Shelf Expedition, station 110, 7.496°N 57.5833°W, depth 47 m, Van Veen grab, 5 September 1970 ; RMNH Por. 9846, Suriname, ‘ Snellius O.C.P.S. ’ Guyana Shelf Expedition, station B24, 7.0733°N 55.4167°W, depth 65–66 m, trawl, sandy mud, 27 April 1966 ; RMNH Por. 9867, Suriname, ‘ Snellius O.C.P.S. ’ Guyana Shelf Expedition, station F45, 6.4417°N 56.5467°W, depth 34 m, Van Veen grab, 7 May 1966 .

Description. ( Figs 29 a,a1,a2) Body rounded to elongate provided with long fistule or fistules. Body size of three specimens 1.5–2 cm in diameter, height 1–3 cm. Lower part of the body provided with root-like projections. Fistules thin-walled, fragile, 2–5 cm in length, 3–6 mm in diameter. Color (in alcohol) white, dirty white or redbrown.

Skeleton. The skeleton of the fistules ( Fig. 29 b) has a unispicular tangential surface reticulation overlying a system of anastomosing lengthwise arranged spicule tracts. The main body has a tangential uni- to paucispicular surface reticulation ( Fig. 29 c) carried by a wider reticulation of subectosomal spicule tracts forming rounded meshes. Internal body has a unispicular confused reticulation.

Spicules. ( Figs 29 d–g) Oxeas, sigmas, toxas.

Oxeas ( Fig. 29 d) lightly curved, sharply pointed, variable in length and thickness between the three specimens, 156– 186 –202 x 5 – 5.9 –7.5 µm.

Sigmas ( Fig. 29 e), thin, angular, in a large size range, 14– 23.4 –39 µm.

Toxas ( Figs 29 f), sharp-angled, with straight legs, ending in upturned apices, in a large size range, 12– 33.4 –66 µm.

Toxas ( Fig. 29 g), fat, bluntly rounded, rare (n=5), 60– 72 x 3–5 µm in thickness.

Distribution and ecology. Guyana Shelf, Bahamas, Jamaica, Cuba, at 8–66 m depth ( Guyana Shelf 34–66 m).

Remarks. The identification of the Guyana material with O. stalagmitica is based on the fact that both have a spicule complement of oxeas, angular sigmas and toxas, but it remains uncertain. There are considerable differences between the present three specimens and Wiedenmayer’s (1977) description. He pictured and described broad-based large specimens provided with numerous thick-walled fistules, while the present material is small, with few thin-walled fistules and rooted bodies. It is possible that the present specimens are juveniles that may eventually grow out to form these large broad thick-fistuled forms. Excepting the rare large fat toxas, the spicule package of the type and the Guyana specimens is largely similar, although the length and thickness of the oxeas is smaller in the Bahamian type material (100–155 x 3.5–5 µm). There was some variability in oxea size among the Guyana specimens, with Por. 9846 having them shorter and thicker (156–170 x 6 –7.5 µm) than Por. 9736 (160–202 x 5 –6.5 µm), so presumably the oxea size in the type falls within the variation of a single species. Lehnert & Van Soest’s (1996) record of this species from North Jamaica, although the shape of their specimen conforms to Wiedenmayer’s specimens, reports the oxeas in a wider size range (125–200 x 4–6 µm), which supports the likelihood that the Guyana specimens are conspecific. Lehnert & Van Soest (l.c.) distinguished smaller and larger categories of sigmas, 10–25 and 40–52 µm, not confirmed in my specimens.

The interpretation of the occurrence of rare fat toxas remains difficult, they may represent a separate spicule category but could also be an environmentally induced modification of the normal toxas.

Alcolado (2002) corrected his earlier record of Rhizochalina carotta Schmidt, 1870 ( Alcolado, 1980) to the present species; however, his original record did not mention the presence of toxas.

Figures

FIGURE 29. Oceanapia cf. stalagmitica (Wiedenmayer, 1977), a, habitus of RMNH Por. 9867 (scale bar = 1 cm), a 1, of RMNH Por. 9736, a 2, of RMNH Por. 9846, b – c, light microscopic images of skeleton, b, skeleton of fistule of RMNH Por. 9867, c, skeleton of main body of RMNH Por. 9736, d – g, SEM images of spicules, d, oxea, e, sigma, f, normal toxas, g, large fat toxa.