Characella poecillastroides, Van Soest & Meesters & Becking, 2014

Van Soest, Rob W. M., Meesters, Erik H. W. G. & Becking, Leontine E., 2014, Deep-water sponges (Porifera) from Bonaire and Klein Curaçao, Southern Caribbean, Zootaxa 3878 (5), pp. 401-443 : 410-411

Characella poecillastroides new species

Figures 6a–d , 7a–e

Material examined. Holotype: RMNH Por. 9247, Caribbean Netherlands, Bonaire, Curoil Dock (Dive 3), 112.137°N 68.286°W, on a coral rock wall at 168 m, coll. L.E. Becking & E. Meesters, field nr. BON3/ BDR031 , 31 May 2013.

Description. Thickly massive, folded plate ( Figs. 6a–c ) of 2–4 cm thick and approximately 20–40 cm in lateral expansion. A fragment of 8 x 2 x 2.5 cm was preserved. Rough/hispid surface due to protruding spicules, which cause strong accumulation of sediment. No oscules visible. Color beige alive underneath greyish sediment layer, white-beige after preservation. Consistency hard, rough, but can be torn rather easily.

Skeleton. Radiate skeleton of long oxeas ( Fig. 6d ), with a relatively low presence of calthrops-like shortshafted triaenes. Microxeas form a rather dense cover at the surface and are abundantly strewn in the choanosome.

Spicules. Calthrops, oxeas, amphiasters, microxeas.

Calthrops-like short shafted triaenes ( Fig. 7a ), cladi straight or curved, in a large size range, cladomes 400- 598 - 800 µm, cladi 200– 345 –500 x 20– 27 – 30 µm.

Oxeas ( Fig. 7b ), smooth, usually somewhat curved, 2600– 3120 –3800 x 35– 46.5 – 62.5 µm.

Amphiasters ( Fig. 7c ), rugose/spined all over, 10– 17 – 25 µm, with 10–16 rays of 2.5– 6 – 10 µm long.

Microxeas, microspined/rugose, in two size classes, larger ones (1, Fig. 7d, 7d 1 ), gently curved and with tapering sharp ends, 170– 232 –275 x 4– 7 – 10 µm, and short ones (2, Fig. 7e, 7e 1 ), abruptly curved and/or centrotylote, 25– 37 –45 x 2–3 µm.

Ecology and distribution. The holotype was collected on a carbonate rock wall just below the mesophotic zone off Bonaire.

Etymology. The name refers to the plate-like shape which is unusual in the genus Characella , but is characteristic for the related genus Poecillastra .

Remarks. The new species is assigned to Characella because of the occurrence of two microxea categories and the predominance of amphiaster microscleres (cf. Cárdenas & Rapp 2012). The habit resembles that of a Poecillastra , but that genus has a single microxea category and diverse streptasters including spirasters. Barbados Poecillastra sollasi sensu Van Soest & Stentoft, 1988: 36 (not sensu Topsent 1890) also has this habit, but differs in having metasters and spirasters, next to amphiasters. This Barbados material was discussed by Cárdenas & Rapp (2012), who pointed out that the species appears intermediate between Poecillastra and Characella in having two sizes of microxeas next to diverse streptasters. Apparently, habit is not a good marker for the two genera, which have been demonstrated to be distinct genetically ( Cárdenas et al. 2011). Characella aspera Sollas, 1886 as reported by Van Soest & Stentoft (1988: 38) from Barbados appears close in spiculation to C. poecillastroides n. sp., but is radically different in habit (see Table 2 and Figs 21a 1 , 21a 2 ). Several specimens were collected during the present submarine dives (BDR027 and 036).

Figures

FIGURE 1. Map showing the positions of Bonaire and Klein Curaçao (Southern Caribbean), where the present collections were obtained. Insets show details of locations and course of dives 2–4 of the Curasub.

FIGURE 2. Plakinastrella stinapa n. sp., holotype RMNH Por. 9252, a. habit of holotype in situ on limestone rockwall W of Bonaire, b. preserved fragments, c. light microscope image of surface skeleton, d. light microscope overview of the spicule complement.

FIGURE 6. Characella poecillastroides n. sp., holotype RMNH Por. 9247, a. in situ off the SW coast of Bonaire, b. on deck, upper surface, c. on deck, lower surface, d. cross section of skeleton showing dominance of long oxeas and microxeas.

FIGURE 7. Characella poecillastroides n. sp., SEM images of spicules of the holotype RMNH Por. 9247, a. calthrops, b. oxea, c. amphiaster, d. large microxeas. d1. detail of surface of large microxea showing microspination, e. small microxea, e1. detail of small microxea.

FIGURE 21. Images of specimens belonging to already known species, briefly characterized in Table 2. All scale bars 1 cm, a. Characella aspera (Sollas, 1886) photographed after collection, from the front, a1. ditto photographed from the side, b. Theonella atlantica Van Soest & Stentoft, 1988, two specimens after collection, c. Discodermia dissoluta Schmidt, 1880, after collection, d. Corallistes typus Schmidt, 1870, after collection, e. Aciculites cribrophora (Schmidt, 1880), in situ, e1. ditto, after collection, f. Gastrophanella implexa Schmidt, 1870, in situ, f1. ditto, after collection, g. Daedalopelta nodosa (Schmidt, 1879), after collection, h. Neopelta perfecta Schmidt, 1880, after collection, i. Leiodermatium lynceus Schmidt, 1870, in situ, j. Hamacantha sp. after collection, k. Phakellia folium Schmidt, 1870, after collection.