Theonella timmi, Samaai & Pillay & Janson, 2019

Samaai, Toufiek, Pillay, Ruwen & Janson, Liesl, 2019, Shallow-water Demospongiae (Porifera) from Sodwana Bay, iSimangaliso Wetland Park, South Africa, Zootaxa 4587 (1), pp. 1-85 : 25-27

Theonella timmi sp. nov.

( Fig. 9 A–G)

Synonymy

Theonella sp. Chill et al. 1997: 16147–1 6152

Material examined. Holotype. SAMC–A24737 (cross-reference TS 859 & Saf 03-Sod 94), Seven Mile reef, Sodwana Bay (27.4580°S, 32.7141°E), South Africa, 0 7 November 2003, collected by T. Samaai, depth 20 m.

Paratype. SAMC–A24738 (cross-reference TS 932 & Saf03-Sod 97) Seven Mile reef, Sodwana Bay (27.4580°S, 32.7141°E), South Africa, 0 7 November 2003, collected by T. Samaai, depth 20 m.

Type locality. Seven Mile reef, Sodwana Bay, east coast of South Africa.

Description. Massive conical to column-shaped sponges, ranging in length 45–100 mm, in width 25–70 mm, and in height 40–80 mm, columns joined in a common base attached to rocky substrate ( Fig. 9A, B ). Surface smooth with slightly raised, irregularly distributed oval-shaped oscules, 2–5 mm in diameter (one per apex); larger specimens have oscules measuring 5–9 mm in diameter, leading to an axial cavity. Texture firm, velvety to the touch, not compressible, difficult to break. Interior soft. Colour in life blue, interior blue; in preservative, beige.

Skeleton ( Fig. 9G ). Choanosomal skeleton composed of smooth tetraclone desmas. Ectosomal skeleton consists of phyllotriaenes with either long, slender or flattened clads. Phyllotriaenes with narrow clads occur in the inhalant areas on the outer sponge surface; while those with massive clads are found in the choanosome. The clads are sparsely tuberculated. Numerous acanthorhabds are found in the ectosome.

Spicules. Megascleres ( Fig. 9 C, D ). Phyllotriaenes various sizes: 312 (211–566) µm × 8–14 µm, n = 10; Tetraclone desmas ( Fig. 9E ), smooth: 316 (268–345 mm) µm, n = 10. Strongyles, slightly curved, modified forms oxeas, distal end rounded or hastate: 410 (316–593) × 5 (5) µm, n = 10. Microscleres ( Fig. 9F ). Acanthorhabds: 17 (16–19) × 2 (2) µm, n = 10.

Substratum, depth range and ecology. The sponge was found shallow on rocky ledges up to a depth of 30 m in open reefs exposed to currents.

Etymology. Named after the late Mr. Peter Timm of Triton diving for his discovery of the Coelacanth off Sodwana Bay, his passion for marine science, for his friendship and logistical and technical support during our collections.

Remarks. The genus Theonella , which includes 22 valid species (Van Soest et al. 2017), is cosmopolitan in distribution, and has been reported from the Indian Ocean, Red Sea, Pacific and Atlantic (rare), from both shallow and deep waters ( Pisera & Lévi 2002). Three species, Theonella complicata ( Carter, 1880) , Theonella conica ( Kieschnick, 1896) and Theonella swinhoei Gray, 1868 are recorded from the WIO region, the latter also observed in South Africa (pers. obser.). Pulitzer-Finali (1993) recorded T. swinhoei and T. conica from Kenya, while Vacelet & Vasseur (1971), Lévi (1956) and Ilan et al. (2004) recorded them from Madagascar, the Seychelles and the Red Sea respectively. Carter (1880) described T. complicata from the Seychelles. Chill et al. (1997) and Schleyer & Celliers (2005) recorded an undescribed blue Theonella sp. from South Africa, while Pulitzer-Finali (1993) described there blue specimens from Mombasa as T. swinhoei . Ilan et al. (2004) however, recorded the blue specimen from the Red Sea as T. conica . Theonella swinhoei and T. conica from the WIO & Red Sea is in need of a taxonomic revision as it may well contain a series of cryptic undetected species. Theonella timmi sp. nov. was first collected in 1997 from Sodwana Bay but identified only as “ Theonella sp. undescribed” in a study that yielded a new cyclic peptide ( Chill et al. 1997). Theonella timmi sp. nov. is here considered well differentiated from the brown Theonella species (e.g. T. conica and T. swinhoei ) that occurs in the WIO. Theonella timmi sp. nov. is easily distinguished from T. swinhoei , which is usually purple-brown, by a combination of characters which include the deep-violet colouration (external and internal), soft interior, the size of the small acanthorhabds [(14–23 x 3.4 – 4.7 µm in T. swinhoei ; Pisera & Lévi (2002) against 16– 19 x 2 µm for T. timmi sp. nov.)], the virtual absence of ectosomal phyllotriaenes with short rhabds, the presence of ectosomal phyllotriaenes with either long, slender or flattened rhabds, the size of the phyllotriaenes [(460–560 µm in T. swinhoei ; Pisera & Lévi (2002) against 211–566 µm for Theonella timmi sp. nov.)], the presence of strongly tuberculated and branched tetraclone desmas and the smaller size of strongyles, sometimes oxea can be seen (700– 900 µm long, 9–11 µm thick in T swinhoei ; Pisera & Lévi (2002) against 316–593 µm long, 5 µm thick for T. timmi sp. nov.), the tips of the desmas are pointed compared with the rounded tips in T. swinhoei .

Kieschnick’s (1896) description of T. conica is as follows: Sponge cone-shaped with a smooth surface. Oscules present and colour is brown. The sponge has a coherent skeleton made up of tetraclone desmas with smooth shafts and phyllotrianes present in the ectosome. Strongyles have expanded ends (‘tylote’). Microacanthorhabds are extremely numerous. Kieschnick (1896) provide no other details of spicule dimensions of the species. Thiele (1900) also makes reference to tylote like megascleres and the presence of small acanthomicrorhabds. Theonella timmi sp. nov. differs from T. conica by the following characteristics: the styles in T. conica are tylote and never oxeas or strongyles; acanthorhabds in T. conica are curved compared to T. timmi sp. nov. where it is straight; the colour of the interior and exterior of T. timmi sp. nov. is very typical deep-blue, compared with the brown colour of T. conica . It is here considered that all specimens being cylindrical shaped (with one large oscule), brown colouration (light brown interior), the presence of tylote megascleres and small curved acanthomicrorhabds is typical of the species T. conica as defined by Kieschnick (1896) and Thiele (1900).

Carter (1880) originally described T. complicata as an excavating, encrusting sponge, with cladocalthrops, 324 µm diameter, having tetractines, 20 µm and triod actines, 45–50 µm long. In contract, T. timmi sp. nov. is massive, conical to columnar-shaped, with a common base, dark to violet-blue colour, both exteriorly and interiorly, with tetraclone desmas, 316 (268–345 mm) and the presence of ectosomal phyllotrianes, 312 (211–566) µm x 8–14 µm and acanthorhabds, 17 (16–19) x 2 (2) µm.

Theonella swinhoei as described by Gray (1868) and Pisera and Lévi (2002) differs from T. conica by the following characteristics: the styles in T. conica are tylote and never oxeas or strongyles; acanthorhabds in T. conica are curved and larger compared to T. swinhoei where it is straight and small. It is here considered that all specimens being cylindrical shaped (with one large oscule), brown colouration (light brown interior), the presence of tylote megascleres and large curved acanthomicrorhabds is typical of the species T. conica as defined above. Theonella timmi sp. nov. is much less common in Sodwana Bay compared to T. swinhoei and T. conica .

Figures

FIGURE 9. Theonella timmi sp. nov. A & B. In situ; C, D. Phyllotriaenes; E. Tetraclone desmas; F. Acanthorhabd; G. Skeletal architecture (G, x10).