Placospongia Gray, 1867

Sandes, Joana, Moraes, Fernando & Muricy, Guilherme, 2024, Taxonomy of Placospongia Gray, 1867 from Northern and Northeastern Brazil, with description of two new species (Porifera: Demospongiae: Clionaida), Zootaxa 5405 (4), pp. 495-525 : 497-523

Genus Placospongia Gray, 1867

Type species: Placospongia melobesioides Gray, 1867 (by original designation).

Diagnosis:Encrusting or branched sponges, covered by smooth cortical plates separated by contractile grooves, where pores and oscules are located. The cortical plates consist of densely packed selenasters and can also contain auxiliary microscleres. The skeletal structure is radiated, with tylostyles tracts that rise from a lower layer of selenasters (basal in encrusting specimens or as a central axis in branched specimens) and reach the cortex, where they support the margins of the cortical plates. Developmental stages of selenasters occur throughout the choanosome. Megascleres are ectosomal or choanosomal tylostyles in two size classes. Cortical microscleres are selenasters and auxiliary microsleres are spirasters, amphiasters, acanthomicrorhabds, spherasters, micro-spheroxyasters and oxyasters in the ectosome and choanosome (modified from Rützler & Hooper 2000, Becking 2013 and David-Colón et al. 2023).

Identification key to all valid species of Placospongia

1 Streptasters absent.................................................................................... 2

- Streptasters present.................................................................................... 3

2 Micro-spheroxyasters absent............................................................................ 4

- Micro-spheroxyasters present............................................................................ 5

3 Acanthomicrorhabds absent............................................................................. 7

- Acanthomicrorhabds present............................................................................ 9

4 Tylostyles I 430–660 µm in length......................................................... P. santodomingoae

- Tylostyles I 860–1200 µm in length............................................................... P. giseleae

5 Spherasters present.................................................................................... 6

- Spherasters absent, micro-spheroxyasters variable in shape, similar to micro-spirasters and acanthomicrorhabds............................................................................................... P. beatrizae sp. nov.

6 Tylostyles I 430–600 µm in length, abundant spherasters............................................... P. cristata

- Tylostyles I 670–1010 µm in length, rare spherasters............................................ P. melobesioides

7 Oxyasters absent...................................................................................... 8

- Oxyasters present.......................................................................... P. decorticans

8 Spirasters with conical spines, abundant spherasters............................................... P. anthosigma

- Spirasters with rugose spines, rare spherasters and immature selenasters similar to amphinolasters...................................................................................................... P. amphinolastra sp. nov.

9 Oxyasters absent..................................................................................... 10

- Oxyasters present............................................................................. P. caribica

10 Greater abundance of spirasters-like microscleres........................................................... 11

- Greater abundance of amphiasters-like microscleres......................................................... 12

11 Two categories of spirasters-like microscleres................................................... P. colombiensis

- One category of spirasters-like microscleres, stout, with long and sometimes bifurcated rays.................. P. ruetzleri

12 Regular amphiasters-like microscleres, with bifurcated rays................................................... 13

- Irregular amphiasters-like microscleres, without bifurcated ends............................................... 14

13 Spherasters present and amphiasters-like microscleres with spaced rays.................................... P. soesti

- Spherasters absent and amphiasters-like microscleres with bifurcated rays or tufs........................... P. carinata

14 Metasters present........................................................................... P. intermedia

- Metasters absent................................................................................ P. mixta