Tetilla muricyi, Fernandez, Julio C. C., Peixinho, Solange, Pinheiro, Ulisses S. & Menegola, Carla, 2011

Fernandez, Julio C. C., Peixinho, Solange, Pinheiro, Ulisses S. & Menegola, Carla, 2011, Three new species of Tetilla Schmidt, 1868 (Tetillidae, Spirophorida, Demospongiae) from Bahia, northeastern Brazil, Zootaxa 2978, pp. 51-67 : 57-63

Tetilla muricyi sp. nov.

( Figs 4 , 5 ; Tables 2, 3)

Holotype. UFBA 2568-POR, estuary of Acara river, Camamu Bay, Mara, south of Bahia State, Brazil (13o56’24.0”S – 39o05’04.0”W), 5 m depth, 25.ix.2004, coll. U. S. Pinheiro.

Paratypes. Estuary of Acara river, Camamu Bay, Mara, south of Bahia State, Brazil (13o56’24.0”S – 39o05’04.0”W), (same collector and depth as holotype), UFBA 2569-POR, 25.ix.2004; UFBA 2570-POR, 19.xii.2004; and UFBA 2571-POR, 07.viii.2005.

Diagnosis. Tetilla muricyi sp. nov. is devoid of microscleres and has a secondary skeleton composed of oxeas on average 500 μm long and 15 μm thick, predominantly reticulate in the subectosomal and choanosomal regions.

Description. Spherical and massive sponges with a thick rhizoid at the underside ( Fig. 4 A). The body of the sponge is usually slightly flattened perpendicularly to its main axis on opposite sides, thereby having two diameters. Largest diameter is on average 29 mm and the smallest 23 mm. The average height of the sponge body is 28 mm. Variably conspicuous external longitudinal grooves are present, usually 6–10, which are distributed from the base of an apical oscule to the basal portion of the sponge body, near the rhizoids. These grooves are usually shallower closest to the oscule, and slightly deeper near the rhizoids. The apical oscule protrudes slightly above the sponge surface ( Fig. 4 B) and bears spicules piercing its outer rim, albeit not in a regular, palisade-like manner. On the underside there is a fairly thick rhizoid for settlement, and among the specimens, the width at the base varied from 16 mm to 26 mm, and the overall length from 15 mm to 65 mm. The surface is slightly rough and hispid. There are some conules formed mainly near the base of the sponge. The consistency is very hard and almost incompressible. The color of the species in vivo is entirely cream, or be cream with dark green parts. Preserved specimens are cream-colored.

Spicules. Megascleres: Oxeas I ( Fig. 5A ), smooth, straight, fusiform, provided with equally long and thin ends: 1116–1990 –2772 μm / 11–23–33 μm. Oxeas II ( Fig. 5 B and G), smooth, varying from straight to slightly curved in one or two points along their length, usually close to the edges. The ends are thin and usually mucronate: 288–546–864 μm / 7.2–17.5–21.6 μm. Prodiaenes I ( Fig. 5 C), rare like-protriaenes, with long rhabdomes uniformly thick: 1584–2650 –4140 μm / 3.5–6.0–9.0 μm. Cladi may have slightly different sizes; major clade: 25–5– 90 μm / 1.8–3.2–5.5 μm. Prodiaenes II ( Fig. 5 D), smaller than prodiaenes I, also rare like-protriaenes: 616–1170– 1960 μm / 1.0–2.5–4.0 μm. Thin cladi: 15–19.0–29 μm / 0.7–1.2–1.8 μm. Anatriaenes I ( Fig. 5 E), are choanosomal, rhabdomes long and gradually pointed; length 1260–1895 –3060 μm. The rhabdome is thicker immediately below the insertion of the cladome; 5.4–6.8–9.0 μm, tapering abruptly to 3.5–3.8–7.2 μm, about 150 μm below that point, and then becoming slightly thicker again (ca. 6 μm) where tapering gradually to the tip. Cladomes with curved cladi bearing very thin ends: 18–39–58 μm / 3.6–5.0–7.2 μm. Anatriaenes II ( Fig. 5 F), exclusively rhizoidal, similar to anatriaenes I in overall morphology, but distinguished by the length of the rhabdomes (over 6000 μm).

Skeleton. Radial skeleton composed of bundles of oxeas I mixed with anatriaenes I extending from the center of the chaonosome toward the ectosome ( Fig. 4 C), where oxeas can pierce the surface up to about 50 μm. The cladomes of the anatriaenes reach the subectosomal region, but only few of these trespass it ( Fig. 4 D). The prodiaenes I and II are mixed with the main tracts in the ectosome, with their cladomes normally protruding up to 200 μm beyond the surface ( Fig. 4 D – F). Prodiaenes II may form tracts among the main tracts in the ectosomal region. Oxeas II are disposed throughout the choanosome and subectosomal region, exhibiting a reticulate or sometimes disorganized arrangement. These oxeas form a halichondroid secondary skeleton ( Fig. 4 C) and as well as the first category, they can also reach the surface ( Fig. 4 D and E). Foreign particles such as sand-grains can be found in the choanosome as well as adhered to the ectosome. There are channels throughout the body of the sponge, showing a wide variation in diameter (ca. 100 to over 1000 μm). Oxeas II surround these channels, both in the choanosome and the subectosomal region. The rhizoids are formed mostly by anatriaenes II and to a lesser extent by oxeas II, both packed by spongin. The cladomes of these anatriaenes were inserted in the sediment, thus anchoring the sponge to the soft substrate. Microscleres were not found in either the body or the rhizoids.

Ecology. Tetilla muricyi sp. nov. occurs at several localities along river Acara, up to approximately 1.5 km from its mouth. This species is exposed to large fluctuations of salinity (0.8 at low tide to 32 at high tide—data obtained by U.S. Pinheiro and M.C. Guerrazzi) and we can therefore classify it as euryhaline. The new species occurs in extensive sympatry with Craniella quirimure in Camamu Bay.

Etymology. The species name is in honour of Professor Guilherme Ramos da Silva Muricy, who greatly contributed to an expanded knowledge of the Brazilian sponge fauna.

Remarks. Prodiaenes markedly predominate over protriaenes in Tetilla muricyi sp. nov.. Therefore, we consider the former a diagnostic feature of the new species. Its secondary halichondroid skeleton is unique in the genus, and thus of considerable diagnostic value. Tetilla muricyi sp. nov. is differentiated from T. pentatriaena sp. nov. by presenting one less category of oxeas and anatriaenes and, in addition, a category of prodiaenes and a unique secondary halicondroid skeleton. Worldwide there are seven species of Tetilla devoid of sigmaspires, three of which occurring in the Tropical Atlantic: Tetilla euplocamos , T. radiata and T. truncata Topsent, 1890 . The first two of these have only one category of oxeas and protriaenes, plus a category of anatriaenes in T. radiata . The third species has only one category of styles and anatriaenes. Tetilla muricyi sp. nov. differs from these three species by its possession of two categories of oxeas and two of anatriaenes, besides its prodiaenes and secondary halichondroid skeleton. Other species lacking sigmaspires were reported from Indonesia ( Tetilla enoi Brøndsted, 1934 , T. pedifera Sollas, 1886 and T. schulzei Kieschnick, 1898 ) and South Australia ( T. globosa (Bear, 1906)) . Tetilla muricyi sp. nov. differs from these as they all possess only one category of oxeas, protriaenes and anatriaenes, but also by their quite unrelated biogeography and non-mangrove habitat.

Figures

FIGURE 4. Tetilla muricyi sp. nov.; A. Holotype; preserved specimen (UFBA 2568 - POR), oval body and a thick rhizoids at the base. B. Longitudinal section of paratype (UFBA 2569 - POR) showing the inner region; arrow indicates apical oscule. Scale: A – B = 2 cm. C. Transverse section (from center to surface) showing the radial skeleton. Scale = 500 µm. D – F. detail of the ectosome. Scales D = 250 µm, E = 100 µm and F = 50 µm.

FIGURE 5. A. Spicules of the holotype of Tetilla muricyi sp. nov.; A. Oxea I, B. Oxea II, C. Prodiaene I, D. Prodiaene II, E. Anatriaene I, F. Anatriaene II and G. detail of the oxea II end. Scale: A – F = 50 µm and G = 5 µm.