(Figure 17)
Type material: Holotype: Sample in 95% ethanol, tissue section and spicule preparation on slides. BELUM Mc 7588. Prion Island Site 2, South Georgia (54°001.862’S, 37° 15.032’W); depth 18m; collected by C. Goodwin, D. Poncet, and P. Brewin, 19 th November 2010.
Paratypes: Samples in 95% ethanol, tissue section and spicule preparation on slides. BELUM Mc 7586. Prion Island Site 2, South Georgia (54°001.862’S, 37° 15.032’W); depth 18m; collected by C. Goodwin, D. Poncet, and P. Brewin, 19 th November 2010. BELUM Mc 7593. Prion Island Site 2, South Georgia (54°001.862’S, 37° 15.032’W); depth 18m; collected by C. Goodwin, D. Poncet, and P. Brewin, 19 th November 2010. BELUM Mc 7621. Right Whale Bay, South Georgia (54°00.173’S, 37° 40.856’W); depth 18m; collected by C. Goodwin, J. Brown and S. Brown, 21 st November 2010.
Etymology: Named after Dr Judith Brown, Diving Officer for the expedition and her husband, Steve Brown, member of the expedition dive team.
External morphology: In situ appearance: Yellow crust, up to 10mm thick. On the surface of the sponge the ectosomal spicule mesh is visible, giving a honeycomb appearance. Three specimens were growing over algae attached to bedrock. One specimen (Mc7621) is a thicker crust in which the surface has developed into a series of small lumps (Fig. 17a).
Preserved appearance: Fragile white specimen which breaks easily into strands formed by the columns of the choanosomal skeleton. The ectosomal layer is more solid and glassily smooth.
Skeleton: The choanosomal skeleton is formed of thick (up to 15 spicules wide) ascending columns of mycalostyles which divide towards the ectosome in a dendritic pattern. The ectosome is a tangential confused layer of mycalostyles. Chelae present throughout skeleton, the larger category are in rosettes (Fig. 17b).
Spicules: Measurements from Mc7588.
Mycalostyles: 448(601)537 by 11.4(15.6)20.3µm base with an oval tylote, other end coming to a rounded point (Fig. 17c).
Anisochelae: two categories 30.5(44.4)52.6 and 67.2(81.7)88.0µm (Fig. 17d, e).
Remarks: This species can be distinguished from most species the subgenus Mycale (Mycale) by its smaller mycalostyle size or the categories of microscleres, which are present (Table 9). It has a similar size range of mycalostyles to M. doellojuradoi Burton, 1940 but this has three categories of chelae, the smallest being 18µm. Descriptions of other species in the genus were examined in case of taxonomic confusions; these could be distinguished by differences in the size of mycalostyles or the categories of microscleres present.