Forcepia (Forcepia) minima, Van, Rob W. M., 2009

Van, Rob W. M., 2009, New sciophilous sponges from the Caribbean (Porifera: Demospongiae), Zootaxa 2107, pp. 1-40 : 24

Forcepia (Forcepia) minima sp. n.

( Figs 9 A–F)

Holotype. ZMA Por. 20880, Netherlands Antilles, Curaçao, Avila Beach, 12.098°N - 68.926°W, 25 m, 03-10- 1991, coll. M. Kielman #S 111.

Paratypes. ZMA Por. 12715, Bonaire, Punt Vierkant, 12.116°N - 68.295°W, under rubble, 5 m, 04-08- 1987, coll. G.J. Roebers # 183; ZMA Por. 20882, Netherlands Antilles, Curaçao, SeaQuarium, 12.081°N - 68.8919°W, 25 m, 1991, coll. M. Kielman #S 54; ZMA Por. 20883, same locality as previous paratype, 25 m, 24-9-1991, coll. M. Kielman #S 62.

Additonal material (not belonging to the type series). Curaçao, Playa Hundu, 12.258°N - 69.127°W, under rubble, 5 m, 1989, coll. E. Meesters & P. Willemsen # H26C13; Curaçao, Cornelisbaai, 12.084°N - 68.897°W, under rubble, 3.5 m, 1989, coll. E. Meesters & P. Willemsen # C23-9; Curaçao, Kaap Malmeeuw, 12.137°N - 68.999°W, under rubble, 12–16 m, 12-1980, coll. R.W.M. van Soest.

Description. Tiny hollow encrustations of approx. 0.5–1 mm thickness and maximum of 2 cm 2 in widest expansion, with one (holotype) or up to three fistules of 2 mm diameter and 4–5 mm high. Consolidating coarse sediment under coral rubble and occupying depressions in the coral rubble. Color pale brown or pale orange, which keeps in alcohol.

Skeleton. Thick irregularly connected bundles of spicules, 50–60 µm in diameter traverse the bladder-like main body, and these fan out at the surface where they get dispersed tangentially, forming an irregular ectosomal skeleton.

Spicules. Tylotes, isochelae, forceps.

Tylotes ( Figs 9 A–B), smooth, curved, with elongate but prominent tyles, which have a characteristically visible elongate axial lumen, 258- 292.9 -345 x 5 - 5.7 -7 µm.

Arcuate isochelae ( Fig. 9 C) with short broad alae, which occasionally show incipient polydentation, 15- 22.3 -24 µm.

Forcipes ( Figs 9 D–F) of varied shape, divisible in two size categories, and each occurring in a heavily or a more lightly spined form, with or without teethed apices: (1) larger heavily spined forcipes, 54- 68.5 -91 µm (widest expansion of legs 20–22 µm), teethed apices; (2) larger faintly spined forcipes, without teethed apices, are in a similar size range and are interpreted as growth stages ( Figs 9 D–E); (3) smaller spined forcipes, 27- 39.5 - 48 mm (widest expansion of legs 10–27 µm), teethed apices; (4) smaller less spined forcipes, without teethed apices have similar size range and are interpreted as growth stages ( Fig. 9 F).

Ecology. Subrubble habitat at shallow and reef crevices at intermediate depths, range 3.5– 25 m.

Etymology. The name refers to the tiny size, the smallest in the subgenus Forcepia (Forcepia) .

Remarks. Up to now, four Forcepia species have been recorded from the Central West Atlantic, Forcepia (Forcepia) colonensis Carter (1874) , redescribed by Van Soest (2002b), based on Forcepia trilabis sensu van Soest (1984) from Panama and Barbados, Forcepia (Forcepia) trilabis ( Boury-Esnault, 1973 as Ectoforcepia ) from Brazil, Forcepia (Forcepia) grandisigmata van Soest (1984) from Jamaica, and Forcepia (Leptolabis) vermicola Lehnert & van Soest (1996), likewise from Jamaica. Of these, F. colonensis is closest in spiculation to our new species and shares a thinly encrusting habit. However, the tylotes (330–360 µm) and larger acanthose forcipes (200–260 µm) of F. colonensis are clearly larger than those of our new species. The chelae of F. colonensis are divisible in two size categories with the larger having reduced alae (see Van Soest, 2002b fig. 3C). F. trilabis is also close, having similar tylote sizes and both acanthose forcipes and relatively smooth growth stages in two size categories, but like F. colonensis this has very large forcipes (even up to 303 µm) and chelae with reduced alae, whereas there is only a single size category, rendering it inbetween F.colonenis and F. minima n. sp. in that respect. F. grandisigmata is more distant in possessing huge sigmas (up to 202 µm) and peculiarly deformed chelae (similar to those of F. fistulosa n. sp. described below).

F. vermicola is distant from the new species by possessing acanthostyles; it is a member of the subgenus Leptolabis .

Figures

FIGURE 9. Forcepia (Forcepia) minima n. sp., SEM images of spicules (Holotype ZMA Por. 20880). A – B. Tylote and detail of one of the apices; C. Diversity of arcuate isochelae; D – E. Spined and smooth larger forceps category; F. Small forcipes.