Clathrina globulosa, Cóndor-Luján & Louzada & Hajdu & Klautau, 2018

Cóndor-Luján, Báslavi, Louzada, Taynara, Hajdu, Eduardo & Klautau, Michelle, 2018, Morphological and molecular taxonomy of calcareous sponges (Porifera: Calcarea) from Curaçao, Caribbean Sea, Zoological Journal of the Linnean Society 183 (3), pp. 459-525 : 474-476

CLATHRINA GLOBULOSA SP. NOV.

( FIG. 7 ; TABLE 5)

Etymology: From the Latin globus (=sphere), for its external morphology.

Type locality: Tug Boat , Caracasbaai, Willemstadt, Curaçao .

Material examined: Holotype. UFRJPOR 6759, Tug Boat , Caracasbaai, Willemstadt, Curaçao (12°04′08.20″N, 68°51′44.40″W) 10 m depth, coll. B. Cóndor-Luján, 23 August 2011 . Paratype. UFRJPOR 6753, same as the holotype.

Diagnosis: Clathrina with cormus formed by a globular clathroid body with an apical water-collecting tube and a solid stalk. The skeleton of the clathroid body is composed of two size categories of triactines. The skeleton of the stalk is exclusively formed by parasagittal tractines. White in life.

Colour: White in life and in ethanol ( Fig. 7A ). Morphology and anatomy: This species has a globular clathroid body with an apical osculum and a stalk ( Fig. 7A ). The surface is smooth and the texture is soft. The consistency is compressible, even the stalk. In the holotype (UFRJPOR 6759), the clathroid body measures 0.5 × 0.5 × 0.1 cm and the stalk is 0.5 × 0.1 × 0.1 cm. The cormus is formed by irregular and tightly anastomosed tubes, which converge at the centre of the sponge forming a single apical osculum.The stalk is solid, formed by tubes without choanoderm (arrow in Fig. 7A ). The aquiferous system is asconoid. No granular cells were observed.

Skeleton: The skeleton of the clathroid body has no special organization and is composed of two categories of regular triactines ( Fig. 7B ). The skeleton of the stalk is composed exclusively of parasagittal triactines, the unpaired actine of which is basipetally oriented. These spicules are more numerous and more closely placed in the median part of the stalk.

Spicules: Triactines I of the clathroid body. Regular (equiangular and equiradiate) or subregular. Frequent. Actines are cylindrical with blunt tips ( Fig. 7C ). Some of them are slightly undulated at the distal part. Size: 67.5–108.0/4.1–5.4 µm. Triactines II of the clathroid body. Regular (equiangular and equiradiate). Actines are conical and straight with sharp tips. Shorter and thicker than triactine I ( Fig. 7D ). Size: 45.9– 62.1/5.4–8.1 µm. Triactines of the stalk. Parasagittal (equiangular). The paired actines are slightly conical and very short (sometimes they seem to be rudimentary). The unpaired actine is straight and cylindrical to slightly conical with sharp tips ( Fig. 7E ). Size: 40.5–67.5/5.4–8.1 µm (paired actine) and 94.5– 199.8/5.4–8.1 µm (unpaired actine).

Ecology: This species was collected in a light-protected environment, underneath coral boulder, at 10 m depth. No associated organisms were found.

Geographical distribution: Southern Caribbean (provisionally endemic to Curaçao, present study).

Taxonomic remarks: Species of Clathrinidae with a clathroid body and a stalk were formerly included in Guancha , but recently those without tetractines were transferred to Clathrina ( Klautau et al., 2013) . These species are: C. arnesenae , C. blanca , C. camura ( Rapp, 2006) , C. challengeri ( Poléjaeff, 1883) , C. lacunosa ( Johnston, 1842) , C. macleayi ( Lendenfeld, 1885) , C. pellucida ( Rapp, 2006) , C. pulcherrima ( Dendy, 1891) , C. ramosa , C. sagittaria ( Haeckel, 1872) and C. stipitata ( Dendy, 1891) . Among them, C. pellucida from Norway and C. stipitata from Australia are the species resembling C. globulosa sp. nov. the most, as these three species have a cormus composed of tightly anastomosed tubes which converging in an apical osculum, and a skeleton composed of regular and sagittal triactines. However, they can be distinguished when additional features are considered.

Clathrina pellucida has a short stalk (less than 1/3 of the body) formed by true tubes with choanoderm and a skeleton exclusively composed of triactines with undulated actines, whereas C. globulosa sp. nov. has a solid stalk half the length of its whole body, and a skeleton which comprises triactines with straight actines.

The skeleton of the clathroid body of C. stipitata comprises parasagittal triactines with unpaired actines regularly arranged, pointing towards the stalk, whereas in C. globulosa sp. nov., it does not include parasagittal triactines, and is formed instead by regular and subregular disorganized triactines. Moreover, Dendy (1891) divides these spicules into dermal and deeper spicules. Dermal triactines are slightly curved with the centre uplifted, resembling a tripod, and deeper spicules are more nearly regular and more slender than the dermal ones. In C. globulosa sp. nov., spicules do not have this external and internal spicule distribution.

In neither of the above referred species, C. pellucida and C. stipitata , were spicules with comparable dimensions to those observed in the clathroid body of C. globulosa sp. nov. mentioned or illustrated in the original descriptions. Triactines from C. pellucida (115.0– 175.0/8.1 ± 1.2 µm) and C. stipitata (unpaired actine: 100.0/10.0 µm and paired actine: 70.0/8.5 µm) are larger compared to C. globulosa sp. nov., even considering its two spicule categories (triactines I: 67.5–108.0/4.1– 5.4 µm and triactines II: 45.9–62.1/5.4–8.1 µm).

Figures

Figure 7. Clathrina globulosa sp. nov. (UFRJPOR 6759). A, specimen after fixation (arrow: stalk). B, tangential section of the clathroid body. C, triactine I. D, triactine II. E, triactine of the stalk.