Arthuria undetermined

Azevedo, Fernanda, Cóndor-Luján, Báslavi, Willenz, Philippe, Hajdu, Eduardo, Hooker, Yuri & Klautau, Michelle, 2015, Integrative taxonomy of calcareous sponges (subclass Calcinea) from the Peruvian coast: morphology, molecules, and biogeography, Zoological Journal of the Linnean Society 173 (4), pp. 787-817 : 793-796

ARTHURIA SPIRALLATA SP. NOV. ( FIGS 2 , 3 ; TABLE 3)

Type material: Holotype (ethanol). MNRJ 11414 – fragments from the holotype: RBINSc-IG 32239-POR 11414, CZA 11414, and MHNG 85411 . Paratypes (ethanol). MNRJ 11397 – fragments from the paratype: RBINSc- IG 32239-POR 11397, CZA 11397 and MHNG 85395 . MNRJ 12860 – fragment from the paratype: RBINSc- IG 32240-POR 12860 and CZA 12860 . MNRJ 16745 – fragment from the paratype: RBINSc-IG 32239- POR 16745 .

Material examined: Six specimens. MNRJ 11397 ; San Cristobal, Lobos de Afuera Islands , Guano Islands and Capes National Reserve System (06°54′52.50′′S, 80°42′55.90′′W); collected by Ph. Willenz and Y. Hooker; 13 m depth; 07.x.2007 . MNRJ 11414 ; San José Inlet , Lobos de Afuera Islands , Guano Islands, and Capes National Reserve System (06°55′48.50′′S, 80°43′16.20′′W); collected by Y. Hooker; 9 m depth; 09.x.2007 . MNRJ 12860 , MNRJ 12864 ; Roquedal , Laguna Grande , Paracas National Reserve, Ica Region (14°09′11.80′′S, 76°15′01.30′′W); collected by Y. Hooker and Ph. Willenz; 1–2 m depth; 12.xii.2008 . MNRJ 13652 ; Sechura Bay site 4, Parachique, Piura Region (05°44′24.10′′S, 80°57′05.60′′W); collected by Y. Hooker and Ph. Willenz; 19 m depth; 07.xii.2009 . MNRJ 16745 ; El Lagarto Islet , Lobos de Afuera Islands , Guano Islands, and Capes National Reserve System (06°56′01.20′′S, 80°42′19.90′′W); collected by E. Hajdu; 12 m depth; 04.x.2007 .

Type locality: San José Inlet , Lobos de Afuera Islands , Guano Islands , and Capes National Reserve System, Peru .

Colour: Opaque white or translucent light beige in life and beige in ethanol.

Etymology: Named from the Latin spira, meaning spiral. Refers to the shape of the apical actine of most tetractines.

Description: Sponge thickly encrusting or massive (3.0 × 1.5 × 0.8 cm) ( Figs 2A–C , 3A–C ). The massive forms are frequently spherical. Consistency is compressible. Cormus is formed by irregular and frequently tightly anastomosed tubes (0.5−1.0 mm). Water-collecting tubes are present, but in some specimens there is only a single osculum. Granular cells were not observed. Aquiferous system is asconoid.

Skeleton: Without any special organization. It is composed of three size categories of triactines and one size category of tetractines; however, tetractines are very rare ( Figs 2D , 3D ). Size categories of tetractines are in the same range as triactines.

Spicules ( Table 3):

1. Triactines I (large): regular (equiangular and equiradiate). Actines are conical or slightly conical, depending on the specimen, and have sharp tips ( Figs 2E, F , 3E–G ). They are found mainly outside the tubes.

2. Triactines II (intermediate): regular (equiangular and equiradiate) or sagittal.Actines are slightly conical with sharp tips ( Figs 2G, H , 3H, I ). This is the most frequent type of spicule. Size highly variable.

3. Triactines III (small): regular (equiangular and equiradiate). Actines are conical with sharp tips. Size highly variable ( Figs 2I, J , 3L, M ).

4. Tetractines: very rare. Size highly variable ( Figs 2K, L , 3J, K ). Apical actines are frequently spiralled, but straight forms also occur ( Fig. 2M, N ).

Reproduction: Unknown

Ecology: This species lives in habitats with moderate to high amounts of sediment. A reasonable quantity of fine sediment was found amongst tubes of the cormus of the holotype specimen ( MNRJ 11414). Some individuals were growing on gastropod shells ( Crepidula sp. ) and others underneath boulders, near polychaete reefs. Specimens were found sharing the substrate with bryozoans, lophophorates, and serpulid polychaetes as well as some other calcareous sponges ( Soleneiscus pedicellatus sp. nov. and Leucosolenia sp. ). Some polychaetes occurred amongst the tubes of the cormus of specimen MNRJ 12860. Known bathymetrical distribution extends from 1 to 13 m depth.

Geographical distribution: North (5°S) and south coasts of Peru (14°S) ( Fig. 3N ) .

Remarks: The genus Arthuria was recently proposed ( Klautau et al., 2013). It comprises eight species: Arthuria africana ( Klautau & Valentine, 2003) ( South Africa), Arthuria alcatraziensis ( Lanna et al., 2007) ( Brazil) , Arthuria canariensis ( Miklucho-Maclay, 1868) (Gulf of Mexico, Azores, Canary and Madeira Islands, Adriatic Sea and European waters), Arthuria dubia ( Dendy, 1891) ( Australia) , Arthuria hirsuta ( Klautau & Valentine, 2003) ( South Africa), Arthuria passionensis ( van Soest, Kaiser & van Syoc, 2011) ( Clipperton Island), Arthuria sueziana ( Klautau & Valentine, 2003) (Red Sea) , and Arthuria tenuipilosa ( Dendy, 1905) (Red Sea and Sri Lanka). Arthuria spirallata sp. nov. differs from all of these by the presence of three categories of triactines and one of tetractines (tetractines being very rare). The frequent spiral shape of the apical actines is also very characteristic. Four specimens of A. spirallata sp. nov. were sequenced and included in our molecular tree.

Figures

Figure 2. Arthuria spirallata sp. nov. (Holotype – MNRJ 11414). A, live specimen (contraction state); B, specimen in ethanol; C, cormus anastomosis (cross section); D, spicules in the wall of a tube (tangential section); E-F, triactine I; G-H, triactine II; I,J, triactine III; K-L, tetractines; M-N, spiraled apical actine of tetractines.

Figure 3. Arthuria spirallata sp. nov. (Paratype – MNRJ 12860). A, live specimen; B, specimen in ethanol; C, cormus anastomosis (cross section); D, spicules in the wall of a tube (tangential section); E-G, triactine I; H, triactine II; I, sagittal triactine; J-K, tetractines; L-M, triactine III; N, distribution map along the Peruvian coast.