Discorhabdella urizae, Maldonado, Carmona, van Soest & Pomponi, 2001

Maldonado, Manuel, Carmona, M. Carmen, Van Soest, Rob W. M. & Pomponi, Shirley A., 2001, First record of the sponge genera Crambe and Discorhabdella for the eastern Pacific, with description of three new species, Journal of Natural History 35 (9), pp. 1261-1276 : 99-4

Discorhabdella urizae n. sp.

Material collected. Holotype USNM-51470 , paratype HBOM-003:00953 .

Type locality. Off the Pacific coast of Panama, Gulf of Chiriqui, Banco Hannibal (7 ° 23.644 ' N, 82 ° 01.797 ' W).

Etymology. This species is named after spongiologist Marõ´a J. Uriz, who has contributed greatly to the development of research on Porifera in Spain.

Description. Dark red, 5-15 cm 2, thinly encrusting colonies growing on a boulder collected between 55 and 73 m deep. Colonies, though physically isolated from each other, were very close, resulting either from fragmentation of a larger colony or gregarious larval settlement. The sponge surface is an epithelium-like ectosome, uniformly microhispid. Oscula measure about 100 μm in diameter, and are neither raised nor showing any appreciable pattern of exhalant canals; ostia are not visible.

The skeleton consists of six spicule types, as follows:

(1) Ectosomal subtylostyles: 180-220 μm ✕ 5-7 μm; straight, with an oval subtyle and a tapering point surrounded by feeble microspines ( figure 2a -c ).

(2) Choanosomal tylostyles: 380-750 ✕ 19-42 μm; with a somewhat curved, conical shaft, typically thickened immediately below the tyle, which is ornamented with tubercles ( figure 1a, d, e ).

(3) Pseudoastros e acanthostyles: 23-37 μm in length; with a hypertrophied, globate tyle (15-26 μm diameter) provided with blunt spines; the shaft is short, conical, ended in either a blunt or sharp point, which is surrounded by a subterminal group of marked spines ( figure 2f -j ).

(4) Isochelae: 26-29 μm in length; with fi ve anchorate teeth (figure 2k -n).

(5) Microxeas: 19-26 μm ✕ 2-3 μm; slightly undulated (spiraster-like), entirely covered by irregularly scattered, long spines ( figure 2n -p ).

(6) Sigmas: 13-16 μm ✕ 1 μm; symmetrical, C-shaped ( figure 2p, q ).

The skeletal arrangement consists of a single, basal stratum of densely packed, astrose acanthostyles that rest on a basal spongin layer, from which choanosomal tylostyles emerge in a hymedesmioid pattern. The ectosomal subtylostyles are arranged in bouquets around the point of the choanosomal tylostyles, which pierce the sponge surface. Sigmas and isochelae are abundant in the ectosome, whereas microxeas appear restricted to the choanosome.

Habitat. This species was common at the collection site, particularly on vertical substrata (submersibl e observations). It grew on rocks, overgrowing red crustose algae.

Taxonomic remarks. The new species is well characterized by its distinctive twisted microxeas, which are clearly differentiated from the straight microxeas with spines in two verticils that characterize the Indian Ocean Discorhabdella incrustans . Microxeas are absent in the two North Atlantic species, Discorhabdella tuberosocapitata and Discorhabdella hindei .

Figures

FIG. 2. Spicules of Discorhabdella urizae n. sp.: (a) comparative view of an ectosomal subtylostyle and a choanosomal tylostyle; (b, c) spiny point of ectosomal subtylostyles; (d, e) detail of the tuberose tyle of choanosomal tylostyles; (f-i) pseudoastrose acanthostyles; (j) tyle of a pseudoastrose acanthostyle, in which the shaft is broken, making it appear similar to a regular sphaeraster; (k-m) isochelae, in which differences in the number of teeth between and within spicules is seen; (n) comparative view of isochela and curved microxea; (o) curved microxea; (p) curved microxea and sigma; (q) sigma.

FIG. 1. Spicules of Crambe panamensis n. sp.: (a) point and tyle of an ectosomal subtylostyle; (b) point of a subectosomal subtylostyle with feeble spines (sp); (c) tyle of a choanosomal tylostyle, where vestiges of a tubercle (tb) can be seen; (d-f) fully grown astroclones with diversely developed actines that show both zygomes (z) and blunt ends (be); (g) early developing stage of an astroclone; (h) comparative view of fully grown desmas (gd) and early developing stages (dd); (i) isochela.