Ophlitaspongia Bowerbank, 1866

El-Arab, Mohammed Abdel Latif Ezz & Ekins, Merrick, 2023, Redescription of Ophlitaspongia (?) arbuscula Row, 1911 and Ophlitaspongia (?) horrida Row, 1911 from the Red Sea, and their placement in Clathria (Clathria) Schmidt, 1862, Zootaxa 5297 (1), pp. 48-60 : 54-57

Parent Ophlitaspongia Bowerbank, 1866

Orig. name Ophlitaspongia (?) horrida Row, 1911:349-351 , pl. 40 fig. 26, text fig. 23

Accepted name Clathria (Clathria) horrida ( Row, 1911)

Material examined: Holotype BMNH 1912.2 .1.63, We Shubuk , Sudanese Red Sea, Dredge , 16.5m Coll. C. Crossland, 1904-1905. Slide of the holotype BMNH 1912.2 .1.65, housed at the Queensland Museum. QM G339443 , Hurghada, Egypt, Red Sea, 27 o 17.80’ N, 33 o 46.26’ E, 5-7 m. SCUBA, Coll. M. A. L. H. Ezz El-Arab, October 2018, NIOF FD100 . QM G339444 , same collection details as QM G339443 .

Distribution: Known only from the Red Sea.

Description: Thin spreading sheets up to 4 mm thick encrusting on corals and calcareous shells. The sponge mass may deviate and protrude from the encrusting level to be a small protrusion without a basal structure as is often the case in the rest of the sponge ( Fig 4 ). The small protrusion may reach to 2 cm length. The actual surface of the sponge is quite smooth, being covered by a very delicate dermal membrane.

The sponge has irregularly dispersed oscula 2–3 mm in diameter and 2.5–3 cm apart. The color is dark-red during life and reddish-brown color in alcohol.

The texture is compressible and resilient when separate off the substrate, can be cut and torn easily.

Skeleton: A flattened basal layer of spongin measures 0.3 mm lying on the substratum, and a hymedesmioid of auxiliary styles or/and echinating (acantho)styles or tylotes oriented perpendicular to the spongin ( Fig. 6B ). Tylotes almost confined to the head regions, project from this basal layer, while the heads of the styles are buried in the spongin. In NIOF FD100, there is a flattened basal layer of spongin with no hymedesmioid of auxiliary styles, or the auxiliary styles in the basal layer may be scarce and hard to find ( Fig. 6C ).

The choanosome of all collected specimens consists of (subtylo)styles and styles cored fibres (0.08 mm in diameter), perpendicular to the substratum which ascend through the sponge from the basal layer to the dermal layer. The fibres are strongly coated with spongin and the reticulation through the choanosome is fairly recognisable, where a distinction into primary and secondary fibres can be made. The primary ascending fibres are abundantly cored by (subtylo)styles and styles, echinated by auxiliary styles or echinating (acantho)styles. Unispicular or paucispicular smaller secondary spongin fibres are perpendicular to and connect with the primary fibres to form choanosomal elongate or square meshes. The fibres in the sub-ectosome are condensed and irregularly oriented. The ectosomal skeleton consists mainly of densely matted brushes of (subtylo)styles arranged tangentially with the tips of the (subtylo) styles projecting from the surface ( Fig. 6D ). As a result, the ectosomal skeleton forms a dense felting over the surface of the sponge.

Loose interstitial styles and toxas are scattered irregularly through the sponge between the fibres.

Spicules:

Megascleres: The megascleres are predominately (subtylo)styles, which are frequently curved, sometimes with subtle swellings, but usually well rounded with slight necks ( Fig. 5C ). They range in length from 61 to 400 µm in the fresh material, and 80 to 335 µm in the holotype ( Table 2). The original description ( Row 1911) recorded only 300 µm ( Table 2). They are slender, and range in width between 1 and 7 µm in the fresh material ( Table 2), and from 1 and 6 µm in the holotype ( Table 2). The original description ( Row, 1911), simply recorded 2 µm in width ( Table 2). The (subtylo)styles in almost all the fibres form a slender core. However, they are frequently arranged in a slightly plumose manner within the sponging-fibre, but they never project outside it. A few spicules occur with oxeote or stylote ends.

(Acantho)styles were also found in some of the fresh material and in the holotype ( Table 2) ( Fig. 5D ). (Acantho)styles are relatively strongly spined, and they range in length from 55.6 to 120 µm in the fresh material and 27.5 to 56 µm in the holotype. (Acantho)styles were not recorded in the original description ( Row, 1911).

Microscleres: Toxas were found in all the samples including the holotype and the original description. However, they are very uncommon to rare in the samples. Oxhorn micro-toxas and wing-shaped short toxas with a range of length from 19 to 300 µm, were found in the fresh material and 200 µm was recorded in the original description ( Row, 1911) ( Table 2) ( Fig. 5E ). Rare oxeas (75 to 120 µm in length), sigmas (15 to 30 µm in length) and palmate isochelas (20 µm in length), were also found in some of the material in Egypt (not listed here), but due to their absence in the type material and the material examined in this study (i.e. Table 2) were regarded as non-native.

Remarks: The holotype of Ophlitaspongia horrida (BMNH 1912.2.1.63) described by Row (1911) as a low irregularly branching mass, creeping on coral and calcareous shells. The recently collected specimens are encrusting, from which arise at frequent intervals stout and short processes which frequently branch. These small protrusions do not have basal structures (hymedesmoid architecture) as is often the case in the rest of the sponge.

In these new specimens (QM G339443 and QM G339444) the skeletal structure has a flattened basal layer of spongin lying on the substratum, and a hymedesmioid of small styles or/and (acantho)styles or tylotes) oriented through the spongin at right angles. Row (1911), in the original description of Ophlitaspongia horrida stated only (subtylo)styles as megascleres, and a few toxas as microscleres. It has been found that there is a consensus between Row (1911) and the recent specimens (QM G339443 and QM G339444) in the presence of the (subtylo)styles and convergence in their dimensions. However, the new material recorded (acantho)styles not mentioned in Row (1911).

Figures

FIGURE 4. Ophlitaspongia (?) horrida. A. the holotype BMNH 1912.2.1.63. B. the holotype BMNH 1912.2.1.63. C. Underwater photograph of O. horrida specimen QM G339443. D. Preserved specimens of QM G339443.

FIGURE 5. Ophlitaspongia (?) horrida the holotype BMNH 1912.2.1.63. A section through the holotype BMNH 1912.2.1.63. B. A magnified section through the holotype BMNH 1912.2.1.63, showing the dense brushes of spicules in the ectosome. C. Style diversity in the holotype. D. (Acantho)styles in the holotype. E. Toxas in the holotype.

FIGURE 6. Ophlitaspongia (?) horrida the fresh material NIOF FD100. A. A Section through the fresh material NIOF FD100, B. A hymedesmioid of auxiliary styles or/and echinating (acantho)styles. C. A flattened basal layer of spongin with no hymedesmioid of auxiliary styles, or the auxiliary styles in the basal layer may be scarce and hard to find. D. The ectosomal skeleton is consisting mainly of densely matted brushes of (subtylo)styles.