Acanthella stanleei, Nascimento & Cavalcanti & Pinheiro, 2019

Nascimento, Elielton, Cavalcanti, Thaynã & Pinheiro, Ulisses, 2019, A new species of Acanthella Schmidt, 1862 (Porifera, Demospongiae, Dictyonellidae) from northeast region, Brazil, Zootaxa 4555 (2), pp. 291-295 : 291-292

Acanthella stanleei sp. nov.

Type specimens. Holotype. UFPEPOR 2329, off Itamaracá Municipality (7°40’0’’S 34°28’7’’W), Pernambuco State, Brazil, depth 60–68 m, st. 36, Pernambuco expedition, 14 February 1969 . Paratype. UFPEPOR 3230, Ceará State (1°30´S 38°48´W), Brazil, depth 45–49 m, st. 14, Canopus expedition, 1965-1966 .

External morphology ( Fig. 1 A–B). Ramose-bushy sponge with flattened shrub growth form measuring 4 x 4.5 x 2.7 (height x length x thickness—measurements of the holotype), irregular branches, with some fragments of rhodolite attached to the body of the sponge. Branches measuring 0.5–1.5 cm (measurements of the holotype). Surface hispid, with ends of large choanosomal strongyles projecting through ectosome. Colour is beige to pinkish brown when preserved, colour in life is unknown.

Skeleton ( Fig. 1 C–D). No specialized ectosomal skeleton. Choanosomal skeleton with ascending, thick and dendritic axes (40– 64 –110 µm) of sinuous strongyles plumo-echinated by styles.

Spicules ( Fig. 2 A–D). Styles (300– 433.6 –660 / 3– 6.2 –8 µm): slightly curved, smooth, telescopic or rounded tips ( Fig. 2 A–B); Strongyles I (310– 430.0 –610 / 5– 6.4 –9 µm): straight to slight curved, smooth ( Fig. 2C ); Strongyles II (400– 777.6 –1030 / 2– 5.1 –7 µm): sinuous, smooth, thinner ( Fig. 2D ); Foreign sigmas microscleres were found in the paratype (45– 60.7 –72 µm).

Etymology. The specific epithet stanleei in honor of the scriptwriter and editor of Marvel Comics, recently deceased.

Discussion. In a recent study, Morrow and Cardenas (2015) placed Dictyonellidae in Bubarida , but the authors also suggest the needing of taxonomic revision due to the presence of three clades mixing species (including Acanthella and other Dictyonellidae , Bubaridae and Axinellidae ). In general, Dictyonellidae is distinguished from Axinellidae by the fleshy surface appearance (velvety in Axinellidae produced by the close-meshed endings of the choanosomal skeleton) ( Van Soest et al. 2002). But several species may be misidentified regularly among the genera of these two families. Lévi (1973) considered Acanthella part of the family Axinellidae . However, in a phylogenetic analysis of the halichondrids, Van Soest et al. (1990) described a new family Dictyonellidae including Acanthella .

Acanthella may be mistaken for the axinellid genus Phakellia Bowerbank, 1862 . Some Acanthella species are senior synonyms of Phakellia species (i. e. A. columnata ( Burton, 1928) accepted as P. columnata ( Burton, 1928) and A. stipitata Carter, 1881 accepted as P. stipitata (Carter, 1881)) . Hooper & Lévi (1993) based on an examination of several species of Phakellia and Acanthella , indicated that the two genera can be separated on the basis of overall shape and skeletal architecture. Members of Phakellia are flabelliform and have an axial and extra-axial skeleton and a reticulate peripheral skeleton. Acanthella species usually have an erect, bushy, ramose, lamellate or lobate habit (with a highly plasticity of the external morphology), lack an axial and extra-axial skeleton, and have a dendritic peripheral skeleton.

Alvarez & Hooper (2010) suggest that identification of Acanthella species using only traditional morphological characters will remain imprecise. However, we believe in this specific case, that morphological characters are reliable to assign the new species in Acanthella , due to the similarities with the type species Acanthella acuta Schmidt, 1862 . When compared both species, they share bushy shape, and choanosomal skeleton of dendritic tracts cored by strongyles and echinated by styles. But, they can be differentiated by the presence of two categories of styles and much larger strongyles in A. acuta . Acanthella stanleei sp. nov. differs from the other five species recorded for the Atlantic by its combination of spicule composition and length of the spicules ( Table 1.).

Acanthella cubensis ( Alcolado, 1984) have much larger styles and strongyles than the new species. In addition, A. cubensis has a variation of the strongyles to strongyloxeas. Acanthella erecta ( Carter, 1876) and A. vaceleti Van Soest & Stentoft, 1988 have smaller styles than the new species. Acanthella erecta also presents strongyles smaller and styles thicker than those of Acanthella stanleei sp. nov. Acanthella mastophora ( Schmidt, 1870) from the Floridian Region is a bushy sponge, with short or long peduncle. They are different in spicule composition, A. mastophora has two categories of styles that present maximum size larger than the styles in A. stanleei sp. nov., and strongyles which can vary to oxeas, while Acanthella stanleei sp. nov. has one category of styles and two categories of strongyles. Additionally, the new species has not peduncle as seen in A. mastophora . The only species recorded for the Brazilian coast is A. flagelliformis ( Van Soest & Stentoft, 1988) that differs from the new species by its cone shape and the presence of two categories of styles and one of strongyles or oxeas. Acanthella flagelliformis also has styles and strongyles larger and thicker than those of the new species. The number of Acanthella species from the West Tropical Atlantic Ocean increases to six with the addition of this new species.

Figures

FIGURE 1. Acanthella stanleei sp. nov. A, (UFPEPOR 3229) preserved holotype; B, (UFPEPOR 3230) preserved paratype; C, thick section showing ectosome and choanosome; D, Detail of skeletal reticulation.

FIGURE 2. Spicule complement of Acanthella stanleei sp. nov. in SEM. A, styles; B, base and tip of styles; C, slightly curved strongyles I; D, sinuous strongyles II.