Mycalina: another crack in the Poecilosclerida framework

Area of Science:

• Marine Biology
• Zoology
• Systematics

Background:

• The sponge suborder Mycalina was established in 1994, but its monophyly and familial relationships within the order Poecilosclerida remained unclear.
• Previous classifications relied on limited data, necessitating a comprehensive analysis integrating diverse evidence.

Purpose of the Study:

• To conduct the first phylogenetic analysis of the sponge suborder Mycalina using both morphological and molecular data.
• To resolve the taxonomic நிலை (status) and evolutionary relationships of families within Mycalina and the broader Poecilosclerida order.

Main Methods:

• Cladistic analysis of morphological characters across key sponge families.
• Phylogenetic analyses of combined partial 16S and 28S ribosomal RNA (rRNA) gene sequences.
• Phylogenetic analyses of a complete 18S ribosomal DNA (rDNA) dataset.

Main Results:

• Morphological analysis supported monophyly for Cladorhizidae, Guitarridae, Isodictyidae, Latrunculiidae, and Podospongiidae, but not for Desmacellidae, Esperiopsidae, Hamacanthidae, and Mycalidae.
• Molecular analyses indicated Mycalina is not monophyletic, with Biemnidae distantly related to other poecilosclerids.
• Merlia and Desmacella were placed near the base of the Poecilosclerida clade; Mycalidae was found to be monophyletic (excluding one species), and Esperiopsidae and Isodictyidae formed a distinct clade.

Conclusions:

• The suborder Mycalina is not a natural monophyletic group based on integrated phylogenetic analyses.
• Molecular data provide crucial insights into the deep evolutionary relationships within Poecilosclerida, necessitating taxonomic revisions.
• Discrepancies between morphological and molecular datasets highlight the complexity of sponge evolution and the need for continued integrative systematic studies.