Theonella conica ( Kieschnick, 1896 )

Calcinai, Barbara, Belfiore, Giuseppe, Pica, Daniela, Torsani, Fabrizio, Palma, Marco & Cerrano, Carlo, 2020, Porifera from Ponta do Ouro (Mozambique), European Journal of Taxonomy 698, pp. 1-56 : 22-26

Theonella conica ( Kieschnick, 1896)

Fig. 13 , Table 1

Discodermia conica Kieschnick, 1896: 530 .

Material examined PONTA DO OURO • 2 fragments, the larger is about 8× 3× 2 cm; 26°49′17.512″ S, 32°53′42.507″ E;

Kev’s; 23.4 m deep; 3 Feb. 2017; Cerrano leg.; PO2 • 1 fragment, 4 ×2× 1 cm; 26°47′34.8″ S, 32°53′57.662″ E; Close; 18.6 m deep; 9 Feb. 2017; Cerrano leg.; PO29 .

Description

The live sponge is irregularly massive, lobate, with oscules either flush with the surface or opening upon mounds ( Fig. 13 A–C). The color of the surface is brown while the body is blueish. The samples preserved in alcohol are ochre with an uneven surface, in some parts microhispid. The consistence is firm and slightly compressible.

SKELETON. Ectosome consisting of phyllotriaenes and with a crust of numerous rhabds ( Fig. 13 D–E). Choanosome formed by tetraclone desmas and brushes of strongyles ( Fig. 13F ).

SPICULES. Phyllotriaenes ( Fig. 13D ) with short clads 40–(57.5)– 87 µm (n = 8) and desmas quite rare; smooth and slightly curved strongyles ( Fig. 13G ) 315–(385, 54.3)– 417 µm ×2.5–(3.25, 2.2)– 7 µm, sometimes modified in oxeas; rhabds ( Fig. 13H ) are straight with oxeote ends and long spines 7–(9.5)– 14 µm.

Remarks

The samples fall in the genus Theonella Lendenfeld, 1903 due to the presence of phyllotriaenes in the ectosome and the microscleres constituted by acanthorhabds.

To date, 20 species belong to the genus, three of which have records in the Atlantic Ocean ( Table 1 ), while for Theonella ferruginea Haeckel in Zittel, 1878 the type locality is unknown ( Van Soest et al. 2019).

Theonella deliqua Hall, Ekins & Hooper, 2014 , T. maricae Hall, Ekins & Hooper, 2014 and T. xantha (Sutcliffe, Hooper & Pitcher, 2010) are devoid of megascleres. Theonella lacerata Lendenfeld, 1907 , T. cupola Burton, 1928 and T. pulchrifolia Dendy, 1922 differ from our samples because their megascleres are strictly oxeas. Theonella cylindrica Wilson, 1925 , T. levior Lendenfeld, 1907 and T. laena Lim & Tan, 2016 have longer strongyles (respectively 600, 500–770 and 600–630 µm long) while T. incerta Thiele, 1900 and T. complicata ( Carter, 1880) have shorter strongyles (respectively 150 and 90–120 µm long). Theonella invaginata Wilson, 1925 , differs in the morphology (vasiform) and in the presence of microrhabs often with oxeate ends. Theonella swinhoei Gray, 1868 differs in its curved microrhabds and in the rounded extremity (often swollen) of the diactinal megascleres (tylotes) with respect to the straight ones in T. conica . Also, T. mirabilis (de Laubenfels, 1954) , from the Marshall Islands, has straight acanthorhabds but a “dull carmine red” ectosome, microtuberculated surface and calthrops-like tetraclone desmas. In T. timmi Samaai, Pillay & Janson, 2019 , the microrhabds are bent.

The original description of T. conica is concise and no spicule measurements are given; the species was described from Halmahera, Indonesia, but records in the Indian Ocean and Red Sea are numerous ( Van Soest et al. 2019). The material examined fits with the published descriptions of this species. In particular T. conica is described by Ilan et al. (2004) with strongyles, but no tylotes, and with straight acanthorhabds. They also underlined that the color of the internal part of this species is deep blue. Moreover, Lévi (1958) described T. conica from the Red Sea with spicules, fitting in shape and size with the present samples. In the examined specimens, very few desmas have been detected; they can be considered as rare spicules, not always produced by the sponge, as Thiele (1900) reported these spicules as being not numerous and scattered.

On the sample PO2, the hydroid Sphaerocoryne sp. (Class Hydrozoa, Phylum Cnidaria) was detected.

Figures

Fig. 13. Theonella conica (Kieschnick, 1896). A–B. The specimen PO2 in situ; in B a fresh cut highlights the blue colored choanosome. C. The specimen PO29 in situ. D. Ectosome with phyllotriaene (arrow) and rhabds. E. Crust of rhabds (SEM). F. Choanosomal skeleton. G. Strongyles. H. Straight rhabds.