Gelliodes fayalensis Topsent, 1892

Sitjà, Cèlia & Maldonado, Manuel, 2014, New and rare sponges from the deep shelf of the Alboran Island (Alboran Sea, Western Mediterranean), Zootaxa 3760 (2), pp. 141-179 : 171-172

Gelliodes fayalensis Topsent, 1892

( Figs. 14 , 15 ; Table 2)

Synonymy. Adocia fayalensis ( Topsent, 1892) : ( Burton 1956,)145.

Material examined. Specimen MNCN-Sp137 DR07 collected from Stn. 7 ( Table 1 , Fig. 1 ).

Macroscopic description. Ovate, cushion-shaped sponge, attached to a small piece of rhodolith ( Fig. 14A–B ). It measures 30 x 20 mm and is fouled around its basal region by a thickly encrusting individual of Haliclona sp. Surface is smooth, consisting of a thin, delicate, translucent membrane. The ectosomal membrane is damaged in many areas of the body, showing a highly cavernous subectosomal tissue. Ectosome damage makes difficult to discriminate the occurrence of oscules from ectosome breakages. The consistency is hard but friable. The color in alcohol is beige.

Skeleton. Megascleres are oxeas in a size range that could well represent two categories. The oxeas in the large category measure 280–400 x 10–15 µm and are slightly curved, typically showing two flexion points ( Fig. 15A–B, E ). The ends are acerate, with occasional malformations ( Fig. 15A, C ). The oxeas in the small category are less abundant, measure 200–270 x 2–5 µm, are regularly curved over their entire length ( Fig. 15A, D–E ), and have relatively regular hastate ends ( Fig. 15A ). Nevertheless, we cannot discard that the smaller oxeas are early developing stages of the larger oxeas. Microscleres are abundant sigmata, 15–27 µm in maximum length ( Fig. 15A, E–F ).

The ectosomal skeleton is a reticule of tangential oxeas made of uni- or paucispicular lines. The choanosomal skeleton is an irregular network ( Fig. 15G ) consisting of compact, primary multispicular tracts of oxeas with moderate spongin ( Fig. 15H ), which branch and subdivide when running from the deep choanosome towards the periphery. Primary tracts are 250–625 µm wide and connect each other by secondary, pauci- or multispicular secondary tracts, which are 125–200 µm wide. Microscleres are abundant at the subectosomal region, also occurring in the choanosome, some partially embedded in the oxea tracts.

Distribution and ecology notes. Rare species, known from the original description of 5 individuals from Azores ( Topsent 1892, 1904), all coming from the Fayal Channel (Azores), growing on gravel bottoms rich in organogenic elements, at depths of 98– 100 m. The herein described Alboranian specimen, collected from a rhodolith bottom at depths ranging from 109 and 130 m, provides the first record of the species in the Mediterranean Sea.

Taxonomic remarks. The spicule complement, the spicule size, and the skeletal organization of the Alboranian individual are strongly similar to those of Gelliodes fayalensis Topsent, 1892 . A minor difference is that Topsent (1892) did not split the oxeas of G. fayalensis into two size categories. Nevertheless, we are not completely certain that the smaller oxeas that we are herein describing are a size category themselves; they could rather be early growth stages. The only size data for oxeas in Topsent's description (1892) is 270 x 9 µm, which approximately represents the median of the size range found in the oxeas of the Alboran specimen.

All specimens described from Azores by Topsent (1892, 1904) were reported to have several distinct oscules. The preservation condition of our Alboranian specimen did prevent us to discriminate oscules from the frequent ectosomal breakages and, indeed, hindered a relevant comparison in terms of external morphology features.

Figures

FIGURE 1. (A) Localization of the Alboran Island in the Mediterranean. (B) Distribution of the 25 studied sampling stations over the bathymetric map of the shelf of the Alboran Island.

FIGURE 14. Gelliodes fayalensis Topsent, 1892. Specimen from the Alboran Island (MNCN-Sp137-DR07), photographed on its both sides while attached to a rhodolith fragment.

FIGURE 15. Gelliodes fayalensis Topsent, 1892: (A) Line drawing summarizing the spicule complement of the Alboranian specimen (MNCN-Sp137-DR07), consisting of fusiform oxeas I (a) with acerate to malformed ends (b), isodiametric oxeas II (c) with acerate ends (d), and sigmata (e). (B) Light microscope view of Oxea I. (C) SEM detail of regular and abnormal ends of oxea I. (D) Light microscope view of isodiametric Oxea II. (E) SEM view oxeas I and II and a sigma. (F) SEM detail of a sigma. (G) Light microscope view of multispiculate tracts of oxeas I and II forming a network. (H) Light microscope detail of a multispiculate tract.