Esperella serpens Von Lendenfeld, 1888: 213.
Mycale serpens; Hallmann 1914: 406, pl. xxiv fig. 6, text-fig. 14; Hooper & Wiedenmayer 1994: 292.
Summary description. (after Hallmann (1914), who studied a fragment of the type specimen) ‘Cake-shaped’ soft sponge of 8 x 5 x 2.5 cm, provided with lax processes. Color dull-grey in alcohol. Choanosomal skeleton loose megascleres with scattered sand grains. Ectosomal skeleton of ramifying spicule fibres partially connected by loose spicule bundles. Spicules consist of mycalostyles, 220–295 x 5 µm, slender anisochelae of 18–27 µm, sigmas 18.5–29 x 1 µm, and trichodragmas 12–25 x 5 µm.
Distribution. E coast of Australia (Port Jackson).
Comment. Although the occurrence of this species is outside our target region, it is possible it may be found to occur more northward. The spiculation reminds of West Australian Mycale (Carmia) cockburniana Hentschel, 1911, but that species lacks ectosomal specialization and it has two sizes of anisochelae (cf. below).
Key to the Mycale (Aegogropila) species of the tropical Indo-West Pacific region
1 Ectosomal intercrossing tracts excessively thick, 500 µm or more, sigmas I in two thickness categories, excessively thick, 90 x 11–14 µm and normal 70–85 x 3–4.5 µm..................................... Mycale (Aegogropila) pachysigmata
- Ectosomal tracts less than 150 µm thick, sigmas I less than 12 µm thick.......................................... 2
2 Toxas or rhaphidotoxas or long thin raphides present......................................................... 3
- No toxas, no rhaphidotoxas, no long thin raphides........................................................... 9
3 Proper toxas, wing-shaped or at least with clear median curve.................................................. 4
- Raphidotoxas or long thin raphides, but no proper toxas....................................................... 8
4 Three anisochelae categories present...................................................................... 6
- Only two anisochelae categories present................................................................... 5
5 Only large sigma I present, no micracanthoxeas.................................. Mycale (Aegogropila) erythraeana
- Both sigma I and sigma II and micracanthoxeas present............................. Mycale (Aegogropila) cf. lilianae
6 Anisochelae III have their upper median alae protruding with a spear-like extension over the lower median alae; also next to single toxas there are toxodragmas are present.............................. Mycale (Aegogropila) prognatha sp.nov. - No anisochelae III with spearlike protrusion of the upper median alae; toxas are not forming toxodragmas.............. 7
7 Anisochelae II have the lower rim of the upper median alae curved outwards assuming a duckbill-shape.......................................................................................... Mycale (Aegogropila) sulevoidea
- Anisochelae II have the upper median alae gradually curved.......................... Mycale (Aegogropila) orientalis
8 Sponge black in life, apparently only a single category of anisochelae................. Mycale (Aegogropila) mannarensis
- Sponge whitish colored, two anisochelae categories................................... Mycale (Aegogropila) furcata
9 Trichodragmas present.......................................................... Mycale (Aegogropila) serpens
- No trichodragmas.................................................................................... 10
10 A single category of anisochelae............................................... Mycale (Aegogropila) phillipensis
- Two or more categories of anisochelae................................................................... 11
11 A single category of sigmas, anisochelae II similar to M. (Ae.) orientalis.................. Mycale (Aegogropila) gravelyi
- Two categories of sigmas, anisochelae II similar to M. (Ae.) sulevoidea.................. Mycale (Aegogropila) cavernosa
Global diversity and distribution of the subgenus Mycale (Aegogropila)
We queried the World Porifera Database (Van Soest et al. 2020) and added the above results from our Indo-West Pacific Mycale (Aegogropila) study to arrive at the current tentative estimate of known accepted species, which numbers 47. Their distribution over the world oceans summarized as the numbers of species found in Marine Ecoregions of the World (cf. Spalding et al. 2007) is presented in Fig. 16. The subgenus is widespread in warmer and temperate waters, with a few (sub-)Antarctic species, and with the highest species density in the Mediterranean-Atlantic regions. This is likely an effect of collecting efforts. Other high diversity regions are the Caribbean and Indonesia.
We take here the opportunity to remove the homonymy between Mycale (Aegogropila) adhaerens subsp. fibrosa Koltun, 1958 (senior primary homonym) and Mycale (Mycale) fibrosa Boury-Esnault & Van Beveren, 1982 (junior primary homonym), by erecting Mycale (Mycale) bouryesnaultae nom.nov. as a replacement name for the junior name, named after Nicole Boury-Esnault.
Taken together, the species of this subgenus are representative of the distribution pattern of the entire genus Mycale (cf. also below Fig. 130).