Arturia trindadensis, Klautau, 2017

Klautau, Michelle, 2017, Taxonomy and phylogeny of calcareous sponges (Porifera: Calcarea: Calcinea) from Brazilian mid-shelf and oceanic islands, Zootaxa 4311 (3), pp. 301-344 : 309-311

Arturia trindadensis sp. nov.

( Figs 2 A–G; Table 3)

Diagnosis. white Arturia with regular and tightly anastomosed tubes and two size categories of triactines and tetractines.

Material examined ( One specimen). Holotype: MNRJ 7372 , Ilha do Sul, Trindade Island, Espírito Santo State, Brazil (20o31'42''S, 29o19'27''w), 13 m depth, coll. G. Muricy, 17 August 2003.

Etymology. From the type locality, Trindade Island, off SE Brazil.

Colour. white in life and beige in ethanol.

Morphology. Oscula were not recognized. The sponge is flat, composed of thin, regular and tightly anastomosed tubes ( Fig 2 A). The size of the holotype is 25 x 20 x 10 mm. Consistency is soft.

Anatomy. Granular cells absent. The skeleton is disorganized, composed of two size categories of triactines and tetractines ( Fig 2 B). Triactines are the most abundant spicules, while tetractines are very rare. Trichoxeas are also rare and they penetrate the tubes perpendicularly.

Spicules ( Figure 2 ; Table 3). Triactine I: Equiangular and equiradiate. Actines are conical and sharp ( Fig 2 C).

Triactine II: Equiangular and equiradiate, larger than triactine I ( Table 3). Actines are conical, with sharp ends ( Fig 2 D).

Specimen Spicule Length (µm) Width (µm) n

min mean sd max min mean sd max

MNRJ 7372 (H) Triactine I 64.8 75.2 4.1 81.0 8.1 9.1 1.5 14.9 28 Triactine II 91.8 115.3 12.5 148.5 12.2 14.2 1.3 17.6 30 Tetractine I 59.4 72.5 6.9 81.0 6.8 8.8 1.4 10.8 20 Apical 29.7 45.3 9.7 64.8 4.1 5.3 0.7 6.8 30 Tetractine II 83.7 107.3 19.1 140.4 9.5 12.0 2.3 16.2 20 Tetractine I: Equiangular and equiradiate. Actines are conical and sharp. The apical actine is thinner and usually shorter than the basal ones ( Fig 2 E); straight, smooth and sharp ( Fig 2 F).

Tetractine II: Equiangular and equiradiate. This spicule is larger than the tetractine I. Actines are conical and sharp ( Fig 2 G). The apical actine is thinner and usually shorter than the basal ones, straight, smooth and sharp. Trichoxeas: Very thin, straight and long.

Ecology. The only specimen was found growing on a vertical wall, at 13 m depth and exposed to direct sunlight. Calcareous algae were found associated with it.

Distribution. Trindade Island, off SE Brazil.

Remarks. A new name for [ Arthuria ] Klautau et al. 2013 is being designated because it is a junior homonym of a mollusc. Hence, according to Art. 53 of the ICZN, the genus name for Calcarea is invalid. Arturia comprises nine species: A. adusta (wörheide & Hooper, 1999); A. africana ( Klautau & Valentine, 2003) ; A. alcatraziensis ( Lanna et al., 2007) ; A. darwinii ( Haeckel, 1870) ; A. dubia ( Dendy, 1891) ; A. hirsuta ( Klautau & Valentine, 2003) ; A. spirallata Azevedo et al., 2015 ; A. tenuipilosa ( Dendy, 1905) ; and A. tubuloreticulosa Van Soest & De Voogd, 2015 . Although Ernstia sueziana ( Klautau & Valentine, 2003) had been considered as Arturia by Klautau et al. (2013), this was a mistake. According to Klautau & Valentine (2003), the skeleton of this species comprises "triactines and tetractines in roughly the same proportions". Therefore, it belongs in Ernstia . Arturia is characterised by the presence of abundant triactines and few tetractines. we re-analised the holotype of this species and confirmed that it belongs in Ernstia .

Comparing A. trindadensis sp. nov. with all the accepted Arturia, the only species with regular and tightly anastomosed tubes (as A. trindadensis sp. nov.) are A. adusta (recently transferred to Arturia by Voigt & wörheide 2015) and A. alcatraziensis . Arturia adusta , however, has abundant granular cells, an important taxonomic character for Clathrinida ( Klautau & Valentine 2003) , while A. trindadensis sp. nov. does not have. The new species can be differentiated from A. alcatraziensis by the presence of diactines in the latter.

Figures

FIGURE 2. Arturia trindadensis sp. nov. A—Holotype after fixation. B—Section. C—Triactine I. D—Triactine II. E— Tetractine I. F—Tetractine I (ap—apical actine). G—Tetractine II.