Dercitus Stoeba luteus (Pulitzer-Finali, 1986)

Van Soest, Rob W. M., Beglinger, Elly J. & De Voogd, Nicole J., 2010, Skeletons in confusion: a review of astrophorid sponges with (dicho-) calthrops as structural megascleres (Porifera, Demospongiae, Astrophorida), ZooKeys 68, pp. 1-88 : 36-39

Dercitus Stoeba luteus (Pulitzer-Finali, 1986) Figs 19 A–D20A–E

Pachataxa lutea Pulitzer-Finali 1986: 74, figs 8-9.

Material examined.

ZMA Por. 10100, Netherlands Antilles, Curaçao, Boca Sami, 20 m, 12.142°N; 69.007°W, coll. P. Willemsen nr. C92 A20, July 1992.

ZMA Por. 14080, Netherlands Antilles, Curaçao, near Carmabi, in reef cave, 10 -20 m, 12.124°N; 68.974°W, coll. I. Wunsch nr. 84, January 1999.

ZMA Por. 21692 (ex MNRJ 6678), Brazil, Das Rocas Atoll, Fenda, 3.8584°S; 33.8057°W, coll. E. Hajdu, M.V. de Oliveira & U.S. Pinheiro.

Description.

The larger specimen (10100) is a thick liver-like mass (Fig. 19A) with flat smooth surface, 8 ×6× 3 cm in size, consistency compact, cheesy to rubbery. Live colour bright yellow, in alcohol dark brown. The preserved specimen shows a darker outer rim of 1-2 mm in thickness over a lighter coloured choanosome. This is not evidence of a cortex, it merely shows that the post-mortem discolouration does not penetrate evenly throughout the sponge. Our specimen conforms in all macroscopical aspects to Pulitzer-Finali’s type. The second specimen is smaller and thinner, approx. 1 ×1× 0.2 cm, dark glistening red, with a slightly bumpy surface. The Brazil specimen is sized 4 ×4× 4 cm, cut off from a much larger sponge.

Skeleton: the ectosome has a dense layer of sanidasters and ‘spherasters’ carried by a similarly dense mass of calthrops. In the choanosome the calthrops and sanidasters are less densely and confusedly distributed. There is no zonation or other structural arrangement of the skeleton.

Spicules: calthrops, sanidasters and compressed spheraster-like sanidasters (pseudasters).

Calthrops (Fig. 19B) are often three-claded, or even irregularly two-claded, some of the cladi may be straight, others are bifid terminally or wavy, of unequal length, stunt ed, irregular, unevenly curved. No dichocalthrops. Cladi 60 –120.2– 174 × 9 –14.9– 21 µm (measurements of both specimens combined), cladomes 102 –193.9– 264 µm.

Sanidasters (Fig. 19C) highly variable in ornamentation and spination, spines not obviously concentrated at the apices, relatively more frequently concentrated in the middle region, 12 –19.6– 26 × 1 –2.3– 4 µm.

Compressed sanidasters (Fig. 19D) are peculiar, irregular, multirayed, with a very thick center and very short rays, which appear spine-like rather than issuing from a common center, 5 –7.7– 9 µm.

Habitat.

Open substrate in deeper parts of the reef, more shallow in caves.

Distribution.

Widespread Central West Atlantic: Puerto Rico, Southern Caribbean, Northeastern Brazil.

Remarks.

The Curaçao material appears indistinguishable from the Puerto Rico type material (MSNG 47681, La Parguera, Puerto Rico, 20-25 m) in overall morpho logy and spicules. Pulitzer’s material measures 7 ×5× 1.5 cm, turning from light yellow to dark brown in alcohol. Consistency was described as fleshy, firm, compressible. Cladi of the calthrops were given as 70-180 µm (60-174 in our material), sanidasters (called microrhabds by Pulitzer) were given as 8-26 × 3-6 µm (12-26 × 1-4 µm in our material). Compressed sanidaster size was not given by Pulitzer but from his drawings can be estimated to be about 7-8 µm (5-9 µm in our material).

Through the courtesy of Prof. Hajdu we received a fragment (Fig. 20A) of a fleshy specimen from the oceanic island groups east of North East Brazil, originally bright yellow, now dark brown in alcohol and staining the alcohol considerably. The fragment showed several differences with the Curaçao and Puerto Rico specimens (see also Table 4): calthrops (Figs 20 B–C) were often more like short shafted triaenes with one cladus considerably longer than the others; they were generally much more irregular and some appeared to have mesotriaene modifications. Length of cladi 33 –82– 123 × 4 –7.5– 11 µm. Sanidasters (Fig. 20D) were only 10 –14– 19 × 0.5 –1.1– 2 µm, and compressed sanidasters (pseudasters) (Fig. 20E) 5 –7.2– 9 µm. These differences may eventually lead to a distinction of a separate Brazilian species but for the time being we emphasize the similarities.

‘Pachataxa’ lutea does not belong to Calthropella (Pachataxa) for two reasons (see also below): (1) it possesses sanidasters, (2) there are no ataxasters, and (3) the spherasters do not resemble true euasters, they are compressed derivations of the irregularly spined sanidaster-like acanthomicrorhabds. In any case, they seem to be morphologically very close to the Red Sea species Dercitus (Halinastra) exostoticus Schmidt (1868 as Pachastrella ) (see above).