Trikentrion laeve Carter, 1879

Soest, Rob van, Carballo, Jose Luis & Hooper, John, 2012, Polyaxone monaxonids: revision of raspailiid sponges with polyactine megascleres (Cyamon and Trikentrion), ZooKeys 239, pp. 1-70 : 38-39

Trikentrion laeve Carter, 1879 Figs 21 A–F

Trikentrion laeve Carter 1879: 294, pl. 27 figs 9-12 (West Africa);

(Not: Carter 1882: 294 = Trikentrion flabelliforme ; nec: Burton 1948 = Trikentrion africanum sp. n.)

Material examined.

Holotype: BMNH 1848.10.4.6 (additional numbers Dh.2, 252), West Africa, coll. Rev. Allen; label text, presumably by Carter, reads Trikentrion Ehlers, very long acuates.

Description.

Multi-branched bush (Fig. 21A), with single stalk of 1.5 cm high, 0.8 cm diameter, from which cylindrical branches spread out dichotomously, ending in approximately 26 smaller terminally rounded branches. Size of entire specimen, which is broken in two unequal parts, 4.5 × 5.5 × 3 cm. Surface optically smooth, but microhispid, with punctate appearance. Consistency (dry) crumbly compressible, colour beige-purplish.

Skeleton: a comparatively loose reticulation of oxeas echinated sparingly with polyactines, forming rounded or squarish meshes of 150-200 µm diameter, with 5 or more oxeas to the sides, no axial specialization. Peripherally there are numerous long thin styles, accompanied by short thin styles.

Spicules: long thin styles, short thin styles, oxeas, polyactines, trichodragmas.

Long thin styles (Fig. 21B), rather curved, 750 –921.8– 1062 × 4 –6.6– 9 µm.

Short thin styles (Figs 21C, C1), often modified to thin oxeotes, wispy, curved, 234 –312.9– 433 × 0.5 –1.4– 2.5 µm.

Choanosomal ‘true’ oxeas (Figs 21D) (not to be confused with diactinal polyactines), straight, or more often centrotylote or abruptly curved, with pointed ends, very common, 175 –204.1– 242 × 6 –9.6– 13 µm.

Polyactines (Fig. 21E), usually three-claded, occasionally four-claded or diactinal, mostly Y-shaped, less often equiangular, with the basal ray provided with strong hook-like spines, basal cladi 59 –69.6– 89 × 10 –11.9– 15 µm, lateral cladi 47 –63.4– 75 × 9 –10.7– 13 µm.

Trichodragmas (Fig. 21F), straight or curved, 32 –48.2– 60 × 4 –8.2– 11 µm.

Distribution.

West Africa (Carter, 1879).

Ecology.

Probably from shallow water or washed up on the beach. No further data.

Discussion.

This is the first redescription after Carter’s report, which is accurate but deficient in omitting the trichodragmas and short thin styles. This is also the first depiction of habit of the specimen and with the details provided here the species is now at least properly described, but it remains ill known. Carter (1879) differentiated this species from Trikentrion muricatum by emphasizing the presence of ectosomal long styles, which appear lacking in Trikentrion muricatum . The shape and surface characteristics of the two are also quite different, and sizes of the oxeas and polyactines are considerably smaller than in Trikentrion muricatum .

Carter (1882) reported this species from Australia, but from his description it is clear that it concerns the species later described as Trikentrion flabelliforme Hentschel, 1912. The two differ significantly in shape (T. flabelliforme being thinner or thicker bladed, lacking rounded branches forming a three-dimensional bush). The three other species of Trikentrion differ by lacking oxeas.

Burton (1948) reported this species from the République du Congo, more to the south, but this specimen lacks oxeas and has a different shape. It is assigned to a new species ( Trikentrion africanum sp. n.) below.