Antho (Acarnia) penneyi ( De Laubenfels, 1936 )

Van, Rob W. M., 2017, Sponges of the Guyana Shelf, Zootaxa 1, pp. 1-225 : 144-146

Antho (Acarnia) penneyi ( De Laubenfels, 1936)

Figures 90 a–j

Holoplocamia penneyi De Laubenfels, 1936: 76 ,

Holoplocamia delaubenfelsi Little, 1963: 45 , fig. 18. Antho (Plocamia) penneyi ; Hooper 1996: 431.

Antho (Plocamia) delaubenfelsi ; Hooper 1996: 430.

Material examined. RMNH Por. 9929, Suriname, ‘ Luymes O.C.P.S. II’ Guyana Shelf Expedition, station I115, 7.21°N 54.8617°W, depth 81 m, triangular dredge, 24 April 1969 ; RMNH Por. 9939, Guyana, ‘Luymes’ Guyana Shelf Expedition, station 63, 7.5833°N 57.0667°W, depth 71 m, sandy bottom, 31 August 1970 .

Description. Two specimens, one is largely encrusting a dead octocoral ( Carijoa riisea ), obscuring its presence to the extent that it looks like an arborescent sponge ( Fig. 90 a). A cross section of a branch reveals a central octocorallian core and peripheral layer consisting of the encrusting sponge skeleton. Height of specimen 4.5 cm, diameter of branches 6–7 mm, thickness of sponge crust 1–3 mm. The second specimen is thickly encrusting (2–3 mm thickness) a dead gastropod shell upon which isolated small digitations and arboresecent clumps of about 1 cm high are formed, demonstrating that it can be incipient arborescent. In both specimens the surface is hispid. Color in alcohol red-brown. Consistency compressible.

Skeleton. ( Fig. 90 b) A rectangular reticulation, with ascending spongin fibers of 40–60 µm diameter cored by single styles, connected at right angles by spongin fibers cored by single acanthostrongyles. Meshes of the skeleton approximately 200 µm in size. Smaller styles echinate the nodes of the skeleton. Subectosomal skeleton consisting of protruding long styles at their base surrounded by small styles. Scattered subtylostyles and microscleres are found at the surface. Microscleres are also crowded in the meshes of the choanosomal skeleton.

Spicules. ( Figs 90 c–j) Styles, acanthostrongyles, subtylostyles, toxas, isochelae.

Styles ( Figs 90 c–e) with smooth curved shaft and with narrowed heads, smooth or microspined, in a wide size range, divisible functionally into three categories, (1) long, protruding styles ( Figs 90 c,c1) of the ectosomal region, 309– 325 –438 x 8 – 13.7 –16 µm, (2) middle-sized ( Figs 90 d,d1) coring the ascending spongin fibers, 108– 172 –255 x 6 – 10.9 –17 µm, and (3) small ( Figs 90 e,e1), echinating the nodes, 138– 169 –219 x 9 – 11.8 –14 µm.

Subtylostyles ( Figs 90 f–g), straight, with faintly swollen heads, which are usually microspined, occasionally smooth, in a wide size range, divisible into two more or less overlapping size categories, (1) larger ( Figs 90 f,f1), 261– 301 –346 x 2 – 3.1 –4.5 µm, and (2) smaller ( Figs 90 g,g1), 175– 216 –246 x 2 – 2.1 –2.5 µm.

Acanthostrongyles ( Fig. 90 h), usually with asymmetrical ending, a good portion acanthostylote, with relatively smooth shaft and spined heads and apices, coring the connecting fibers, 156– 199 –228 x 8 – 10.6 –13 µm.

Toxas ( Fig. 90 i), with a shallow curve, with smooth, sharp apices 27– 80 –141 µm.

Palmate isochelae ( Fig. 90 j), strongly twisted, often somewhat eroded, 10– 12.2 –13 µm.

Distribution and ecology. Guyana Shelf, Florida /Gulf of Mexico, 2.5–81 m depth ( Guyana Shelf 71–81 m).

Remarks. De Laubenfels’ material originated from 70 m off the S coast of Florida. The overall spicule complement and the skeletal structure of the holotype and the present specimens appear similar, but with individual spicule sizes slightly lower in the type.

The specimens could be compared with a slide made from the holotype of Holoplocamia delaubenfelsi Little, 1963 , USNM 23596, from the Gulf coast of Florida, but from only 2.5 m depth. Similar to my specimens the type of that species completely overgrew a dead shell of an oyster appearing massive, but in fact was only encrusting. Little’s description and drawings of the spicules are closely similar to the present specimens, but also here the sizes of the spicules are slightly smaller. Little differentiated his H. delaubenfelsi from H. penneyi largely on the alleged absence of a twist in the chelae, but other than that they are twisted on average only a quarter turn rather than a half turn as in the present specimens and in De Laubenfels’ material, there are no real differeces. There can be no doubt these spicules are closely comparable, so I here propose to assign H. delaubenfelsi to the synonymy of A. (A.) penneyi .

Figures

FIGURE 90. Antho (Acarnia) penneyi (De Laubenfels, 1936), a, habitus of RMNH Por. 9929 (scale bar = 1 cm), b, light microscopic image of a cross section of the skeleton, c – j, SEM images of spicules, c, large ectosomal style, c 1, details of c, d, middle sized choanosomal style, d 1, details of d, e, echinating small style, e 1, details of e, f, large ectosomal subtylostyle, f 1, details of f, g, small ectosomal style, g 1, details of g, h, acanthostrongyle, i, toxa, j, twisted palmate isochela.