A diversidade da Ordem Suberitida (Filo Porifera) sob a luz dos caracteres morfológicos, assinaturas metabólicas e sistemática molecular

Abstract

Sponges represent the most basal group of the animal kingdom containing simple and high plastic morphology, turning their identification difficult. Skeletal structure and spicule set of representatives of the order Suberitida vary from order to species level, and much of their classification is based on the absence of diagnostic characters. The objective of this study was to identify group representatives through morphological, chemical and genetic data. For this, growth shape, color, habitat, type and size of spicules and skeletal architecture were analyzed. Additionally, the metabolic signature and cytotoxic potential of the species were evaluated. Morphological and chemical data were compared to phylogenetic reconstructions obtained by four molecular markers, two nuclear markers (28S and ITS2) and two mitochondrial markers (COX1 and 16S), in order to better understand the group systematics. The secondary structure of the ITS2 gene was tested with success as a new phenotypic character. All of these techniques were employed in specimens collected over four years of research in the Brazilian coast, the Caribbean Sea, the Gulf of Mexico, and Monaco, as well as several comparative Suberitida specimens previously deposited in Porifera collections. A total of 174 individuals were morphologically presented, 52 chemically and 459 compared in phylogenies. In Suberitida, 32 UTOs were identified in 11 genres. Three new genera were proposed (Ditylos, Solistyla and Tenebria) and one (Rhaphidostyla) was resurrected, and five species were identified as new: Halichondria sp. nov., Hymeniacidon sp. nov., Rhaphidostyla sp. nov., Suberites sp. nov. e Topsentia sp. nov. Characteristics such as growth shape, surface type and structure of the ectosomal and subectosomal skeleton were diagnostic for representatives of various genres. Thus, the Suberitida order no longer needs to be sorted by the absence of characters. The metabolic signatures showed differences from order to species level, indicating high utility for taxonomic support, with emphasis on phosphocholins, glycolipids and aminosulfated sterols, and detection of plastic pollutants. The phylogenetic reconstructions with the four molecular markers rescued similar histories, with some specificity regarding the marker type and inserted sample. In all phylogenetic reconstructions, the type species of the genus Terpios grouped in the family Halichondriidae. In general, six clades were observed with high statistical support, with the Halichondriidae family still needing the most attention. Some representatives of the genera Axynissa and Topsentia have grouped out and unrelated to the Submissive order, indicating the possible existence of another order, here named “Topsentiida”. The morphological and metabolic characteristics overlapped and were in agreement with the phylogenetic relationships proving the efficiency of the techniques in favor of the integrative taxonomy. Given the results, the three families of the order Suberitida have 29 genera and 451 species, of which only 52 (11.5%) are distributed in the Western Tropical Atlantic Ocean.