Agelas sansibarica Perino & Pronzato

Manconi, Renata, Pronzato, Roberto & Perino, Erica, 2016, A new species of Agelas from the Zanzibar Archipelago, western Indian Ocean (Porifera, Demospongiae), ZooKeys 553, pp. 1-31 : 3-4

Taxon classification Animalia Agelasida Agelasidae

Agelas sansibarica Perino & Pronzato sp. n. Figs 1, 2, 3, 4, 5

Material examined.

Holotype: MSNG 57991 (A30), 70% ethanol, Jambiani (06°18'44.8"S, 39°33'32"E), eastern coast of Unguja Island, Zanzibar Archipelago, United Republic of Tanzania, SCUBA diving, 4.vii.2010, leg. Mr. Okala. Paratypes: MSNG 57992, MSNG 57993, MSNG 57994, MSNG 57995, MSNG 57996 (A12, A26, A27, A28, A29, respectively) ibid.

Diagnosis.

Agelas with unique spicular complement composed of three spicular categories, oxeas, styles and strongyles with spines arranged in a variable number of verticilles.

Etymology.

The speciphic epithet refers to the Zanzibar Archipelago.

Habitat.

Coral reef, quite common at 7-12 m of depth. Water temperature 28-31 °C. Salinity 20-36‰ ( Fryday 2011). As reported by the Swiss Marine NGO manager of the local sponge farming facility (Jambiani Lagoon) the new species is massively farmed (Christian Vaterlaus, pers. comm., 2010).

Geographic distribution.

Western Indian Ocean, but only recorded from the type locality to date.

Description.

Growth form massive, thick, rounded, 6-10 cm in diameter. Colour in life purple to orange and light brown. Consistency firm and elastic. Surface rough to the touch, finely hispid, finely conulose for tips of ascending fibres supporting the dermal membrane, with regularly scattered circular and convoluted depressions (0.5 cm in diameter) very similar to those of Agelas cerebrum . Oscules few, small, irregularly scattered. Choanosomal skeleton as an irregularly reticulate network of spongin fibres. Primary fibres 50-110 (71.67 ± 17.63) μm in diameter, strongly echinate by single, scattered spicules to groups of diverging spicules; ascending primary fibres cored by spicules also present. Secondary fibres 20-50 (35 ± 9) μm in diameter notably echinate and cored by spicules. Tertiary network not observed.

Megascleres as three categories of monaxons mostly with acute spines. Acanthostyles 90-250 (180.72 ± 28.66) × 7.5-20 (13.46 ± 2.59) μm ornate by verticillate spines arranged as 11-27 (17.8 ± 2.86) whorls. Acanthoxeas 130-295 (195 ± 43.09) × 7.5-15 (12.17 ± 1.89) μm ornate by verticillate spines arranged as 14-26 (19.24 ± 3.47) whorls. Acanthostrongyles 80-245 (148.18 ± 36.82) × 4-17 (11.09 ± 4.24) μm ornate by verticillate spines arranged as 9-26 (15.76 ± 3.85) whorls. Annulate spicules apparently young.

Remarks.

The new species is characterized by the co-presence of three categories of spicules never recorded in other Agelas species. Acanthostrongyles are abundant, ca. 20-30 % of the total number of spicules.