Haliclona (Flagellia) amirantensis, Van Soest, 2017

Van Soest, Rob W. M., 2017, Flagellia, a new subgenus of Haliclona (Porifera, Haplosclerida), European Journal of Taxonomy 351, pp. 1-48 : 19-21

Haliclona (Flagellia) amirantensis subgen. et sp. nov.

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Fig. 10

Gellius flagellifer Dendy, 1922: 26 .

Haliclona flagellifer – Burton 1959b: 218.

Gelliodes flagellifer – Vacelet et al. 1976: 83, Fig. 62.

Sigmadocia flagellifer – Pulitzer-Finali 1993: 327.

non Gellius flagellifer Ridley & Dendy, 1886: 323 ; 1887: 42, pl. XIII figs 5,10.

Etymology

The specific epithet refers to the type locality.

Material examined

Holotype

SEYCHELLES: Amirante Islands , N of Ile Desnoeufs, 6.1333° S, 53.0333° E, 54 m depth, trawl, coll. R. W.M. Van Soest, IOP-E Expedition stat. 782, field number 783/03, 2 Jan. 1993 ( ZMA Por. 12409).

Description

The sponge ( Fig. 10A , circle) forms a central encrustation of approximately 2 × 2 × 0.5 cm on a large Topsentia knoll of 9 cm high and wide. It has an irregular outline around a 5 mm diameter oscule. The color of both sponges was noted as beige and the specimen of Haliclona (Flagellia) was only detected by its softer consistency and a less coarse surface.

SKELETON. Confused anisotropic organization with large open spaces, with spicule tracts cored by 1–6 spicules in cross section bound by spongin, but this is not obviously enclosing the tracts. Interconnecting spicules are single oxeas, arranged loosely and irregularly. The surface has a tangential arrangement of single spicules differentiated from the choanosomal reticulation.

OXEAS ( Fig. 10 B–B1). Slightly curved, gradually tapering to sharp points, 207– 234 –270 × 7.5– 9. 7 – 12 μm.

FLAGELLOSIGMAS ( Fig. 10 C–D). Circular to ovoid in shape, with long endings having either an upturned ( Fig. 10D 1 ) or straight curvature ( Fig. 10C ), and with short endings having a rather wide curvature ( Fig. 10D 2 ). There is a extensive range of sizes, but no clear division in larger and smaller categories. Long endings 58–106–130 μm, short endings 52– 77 –93 μm, width 33– 81 –108 μm, and thickness 1.5– 2. 4 –3.5 μm.

NORMAL SIGMAS ( Fig. 10 E–F). Two distinct size categories, larger (I) ( Fig. 10E ), robust, 47– 54 –63 × 2.5– 3. 2 –3.5 μm, and smaller (II) ( Fig. 10F ), thin, 26– 30 –33 × 0.5– 1. 1 –1.5 μm.

Distribution and ecology

Seychelles, epizoic on sponge in sandy bottom beyond reefs, 50 m depth. Also, if synonymy is correct, Madagascar, Kenya, Maldives, and possibly Saya de Malha (Marine Ecoregions Seychelles, East African Coral Coast, Western and Northern Madagascar, Maldives), 37– 229 m.

Remarks

The description by Dendy (1922) of a fairly large encrusting specimen (5.5 × 5 × 1 cm) from Saya de Malha (98 m depth) with the name Gellius flagellifer Ridley & Dendy, 1886 possibly conforms to the present species. The flagellosigmas were described as having an upturned curve on the long ending and the presence of visible spongin was also noted. However, the sizes of the oxeas were given as 370 × 20 μm, well in excess of the Seychelles specimen, and no data on sizes of flagellosigmas and normal sigma were provided. This meagre information is not sufficient to be certain of conspecificity.

Burton (1959b) reported Haliclona flagellifer from the Southern Red Sea (26 m) and the Maldives (229 m). The specimen from the Southern Red Sea had oxeas only 170 × 10 μm, clearly smaller than the above measurements. The Maldives data appear closer, with oxeas 320 × 19 μm, flagellosigmas 90 μm, and sigmas 30–60 μm.

Vacelet et al. (1976) recorded Gellius flagellifer from Southwestern Madagascar (at 37 m depth, beyond the reefs) and this description matches the above description in most aspects (color, skeleton, sizes and shapes of oxeas and flagellosigmas), except for the normal sigmas, which were given as 30–40 × 1.2–2 μm. However, their drawing of these spicules (fig. 62c) shows considerable size variation. There is little doubt that the Madagascar and Amirante material are conspecific.

Pulitzer-Finali (1993) reported Sigmadocia flagellifer from deeper water (117–138 m) off the coast of Kenya. Oxeas were somewhat larger (310–370 × 13–17 μm), but flagellosigmas and the larger normal sigmas were similar in size. No mention was made of a smaller sigma category, rendering conspecificity uncertain. However, as the specimen also encrusted a sponge ( Asteropus ), this material has more similarities than differences.

Haliclona (F.) hentscheli nom. nov. as described above is quite similar to the Seychelles species in shape, oxea length, shape of the (large) flagellosigmas and presence of two size categories of normal sigmas. The major difference is the lack of a differentiated small flagellosigma category and the size of the larger normal sigma category, which is clearly smaller (average 54 μm) than that of H. (F.) hentscheli nom. nov. (av. 71 μm). Haliclona (F.) flagellifera ( Ridley & Dendy, 1886) subgen. et comb. nov. from Marion Island (see below), differs from H. (F.) amirantensis subgen. et sp. nov. in the shape of both the larger and smaller flagellosigmas, the presence of upturned long endings in many of the large flagellosigmas, the presence of two normal sigma categories, and the smaller sizes of the oxeas. A specimen of H. (F.) flagellifera reported from Kerguelen by Boury-Esnault & Van Beveren (1982) does have flagellosigmas with upturned endings, but is otherwise (oxea sizes, shape of the flagellosigmas, normal sigma sizes) clearly different from H. (F.) amirantensis sp. nov. Additional comparisons are given below.

Figures

Fig. 10. Haliclona (Flagellia) amirantensis subgen. et sp. nov., holotype (ZMA Por. 12409), from Desnoeufs Island, Amirantes, Seychelles. A. Habitus (encircled) encrusting a large Topsentia specimen (scale bar = 1 cm). B–F. SEM images of the spicules. B. Oxeas. B1. Detail of one of the apices. C–D. Flagellosigmas. D 1. Detail of long ending of flagellosigma. D 2. Detail of short ending of flagellosigma. E. Large sigma category (I). F. Small sigma category (I).

Fig. 1. Flagellosigma, the characteristic feature of Haliclona (Flagellia) subgen. nov., showing meristic and descriptive features used in this study.

Fig. 2. ‘Flagellated’ sigma of Mycale (Naviculina) diversisigmata Van Soest, 1984, a sigma type superficially similar to a flagellosigma, but the morphology is considered non-homologous due to the lack of a strong asymmetry in the longer and shorter endings.