Clathria (Microciona) mytilifila Hajdu, Desqueyroux-Faundez, Carvalho, Lobo-Hajdu and Willenz 2013
Creators: name: Hajdu, Eduardo
name: Desqueyroux-Faúndez, Ruth
name: Carvalho, Mariana De Souza
name: Lôbo-Hajdu, Gisele
name: Willenz, Philippe
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Porifera
Demospongiae
Poecilosclerida
Microcionidae
Clathria
Clathria mytilifila

description: Clathria (Microciona) mytilifila Hajdu, Desqueyroux-Faúndez, Carvalho, Lôbo-Hajdu and Willenz sp. nov.
(Figs. 6E, 10A–I; Tab. 7)
Clathria mytilifila Hajdu et al. (2009, nomen nudum) in Willenz et al. (2009: 122)
Type material. Holotype. IZUA-POR 147, Tambor, Comau Fjord (42º24’09.66”S – 72º25’14.10”W, Chilean Patagonia), 5–6 m depth, coll. G. Lôbo-Hajdu and Ph.Willenz, 20 April 2004 —fragments from the holotype: MNRJ 8198 and RBINSc-IG 32231-POR 8198.
Comparative material. Clathria (Microciona) discreta (Thiele, 1905) — MHNG 36566 (fragment from holotype ZMB 3302), microscopical preparations of thick sections.
Clathria (Thalysias) membranacea (Thiele, 1905) — MHNG 18841 (fragment from holotype ZMB 3304), microscopical preparations of dissociated spicules and thick sections.
Clathria (Cornulotrocha?) polita (Ridley, 1881) —MNHN LBIM NBE 915 (presumably from BMNH type), microscopical preparation of dissociated spicules
Diagnosis. Clathria (Microciona) mytilifila sp. nov. is the only crustose Clathria in the Magellanic region and adjacent areas which has no megascleres larger than 250 µm and no isochelae larger than 10 µm. It has large, rare toxas (mean length ca. 200 µm) and highly conspicuous, stout, heavily spined acanthostyles.
Description (Fig. 6E). Thin crust (<1 mm thick) covering approximately 3 x 4 cm in area. Soft and fragile, easily torn. Live-colour yellowish-beige, turning beige after preservation in ethanol.
Skeleton (Fig. 10A). Ectosomal skeleton composed of dispersed, loose brushes of subtylostyles. Choanosomal skeleton composed of short, ascending, sinuous, paucispicular tracts of acanthostyles, replaced by the ectosomal subtylostyles when approaching the surface of the sponge.
Spicules (Figs. 10B–I). Megascleres, ectosomal smooth subtylostyles (Figs. 10D–E), 105– 149.0 –195 µm long and 2.5 µm thick. Choanosomal (sub)(tylo)styles (Figs. 10B–C), frequently basally microspined, straight, 138– 183.7 –226 µm long and 5–6 µm thick. Choanosomal acanthostyles in two categories of similar dimensions, both occurring erect on the substrate as well as free in the choanosome and less frequently, the ectosome. Acanthostyles 1 (Fig. 10F), spined all over or pauciacanthose on apical third or fourth, spines variably prominent, 164– 243.8 –282 µm long and 9–10 µm thick. Acanthostyles 2 (Fig. 10G), heavily spined, spines sharp, stout, frequently bent towards the base, 87– 120.1 –171 µm long and 10–20 µm thick. Microscleres, palmate isochelae (Fig. 10H), 7.5– 10.5 µm long. Rare toxas, in two categories. Toxas 1 (Fig. 10I), slightly bent only at central portion, 148– 211.0 – 307 µm long. Toxas 2 (not seen in SEM), variously deeply curved, 36– 41.7 –60 µm long.
Distribution and ecology. The species is so far known only from its type locality close to the Tambor waterfall, Comau Fjord, 5–6 m depth. Epibiotic on Mytilus chilensis, the “chorito”, and some barnacles in Comau Fjord, 5–6 m depth. This shallow occurrence suggests the species may be tolerant to reduced salinity levels.
Etymology. The name ‘mytilifila’ is derived from the species’ epibiontic occurrence on Mytilus chilensis (Bivalvia).
Remarks. Only seven additional crustose species of Clathria are known from southern South America and the sub-antarctic and Antarctic areas, viz. C. (Cornulotrocha) polita comb.nov., C. (Co.) rosetafiordica, C. (Microciona) antarctica (sensu Burton 1934, as Microciona basispinosa), C. (M.) matthewsi, C. (Thalysias) amabilis, C. (T.) koltuni and C. (T.) membranacea (Table 7). The new species differs from all these by important morphologic features, such as the occurrence of considerably larger megascleres in all, absence of isochelae in C. (M.) antarctica, C. (T.) amabilis and C. (T.) koltuni, as well as occurrence of larger isochelae in C. (Co.) polita (see below) and C. (T.) membranacea, and of anisochelae in C. (C.) rosetafiordica. Additionally, C. (Co.) polita, C. (T.) amabilis and C. (T.) koltuni do not possess toxas, while the toxas in C. (M.) antarctica, C. (M.) matthewsi, and C. (T.) membranacea do not attain dimensions nearly as large as seen in category I of the new species.
The holotype of Hymedesmia polita (BMNH 1879.12.27.22) was reexamined and it is transferred here to Clathria (Cornulotrocha). It’s spicule complement was remeasured and found to contain basally acanthose principal styles (N=7) 257– 340.1 –434 µm long and 8–15 µm thick, auxiliary styles (N=4) 202–366 µm long and 4– 6 µm thick, accessory acanthostyles (N=10) 130– 152.2 –174 µm long and 9–16 µm thick, and isochelae (N=2) 15.5–17.5 µm long.
Another 340+ species of Clathria are listed in the World Porifera Database (van Soest et al., 2013). An important part of these are classed in subgenera Clathria (Axosuberites), 17 spp.; C. (Clathria), 110+ spp.; C. (Dendrocia), 8 spp.; C. (Isociella), 6 spp.; and C. (Wilsonella), 15 spp.; whose anatomy differ considerably from that observed in the new species. Frequently, these will show copious amounts of spongin. Of the remaining, C. (Microciona) includes ca. 90 species, C. (Thalysias) includes ca. 95 species, and 6 species of Clathria remain unassigned to currently used subgenera.
Table 7 compiles information on habit, distribution (both geographic and bathymetric) as well as on the spicule component of 23 species of Clathria sorted from among C. (Microciona) and C. (Thalysias) —subgenera with architectures comparable to that seen in the new species. These are the species occurring in the Chilean-Peruvian biogeographic region, its neighbouring areas, and in New Zealand, and five of these have already been discussed above. It is important to highlight that some of the species in the table are either mistakenly described in the bibliographic sources we used, or rather belong to other genera or subgenera. Such is the case of C. brepha, C. pustulosa, C. sigmoidea and C. spongigartina. Clathria brepha, C. pustulosa and C. spongigartina possess isochelae which are truly or possibly arcuate, which suggests a closer proximity to Phellodermidae van Soest & Hajdu, 2002. Clathria pustulosa and C. sigmoidea were described with sigmas too, a character postulated to be absent from the entire Microcionina (Hajdu et al. 1994). In the case of the former, this is a further suggestion of affinity with Phellodermidae. These species are thus deemed to be only distantly related to the new species described here. Within the fifteen species remaining in Table 7, nine are cushion-shaped, erect, flabellate or digitiform, which renders unlikely their conspecificity with the new species: C. (M.) discreta (microscopical preparations from holotype examined), C. (M.) ixauda, C. (M.) microjoanna, C. (M.) parthena, C. (M.) scotti, C. (T.) lissocladus, C. (T.) originalis and C. (T.) paucispicula. Among these, C. (M.) parthena, C. (M.) scotti and C. (T.) paucispicula have megascleres which can be much larger (> 350 µm long) being thus further differentiated from the new species. In addition, none of these has toxas as those reported here from the new species. C. (T.) lissocladus, C. (T.) originalis and C. (T.) paucispicula do not possess toxas at all, and can still be further set apart from C. (M.) mytilifila sp. nov. through the smooth principal styles reported from C. (T.) lissocladus, the lack of acanthostyles in C. (T.) originalis, and of isoquelae in C. (T.) paucispicula. C. (M.) discreta, C. (M.) ixauda, C. (M.) microjoanna and C. (M.) parthena have considerably smaller toxas, which in the case of C. (M.) microjoanna occur in a single size category. C. (M.) scotti has toxas that can be much larger than those in C. (M.) mytilifila sp. nov., and can be further distinguished from the new species by its lack of isochelae.
Seven species remain which share the crustose habit with the new species: C. (M.) californiana, C. (M.) coccinea, C. (M.) dendyi, C. (M.) leighensis, C. (M.) novaezealandiae, C. (T.) coriocrassus and C. (T.) membranacea (microscopical preparations from holotype examined). All these species have important points of distinction as regards the new species. Clathria (M.) coccinea, C. (M.) dendyi, C. (M.) leighensis, C. (T.) membranacea and C. (T.) coriocrassus possess megascleres which may be considerably larger (> 350 µm). The latter has no toxas either. C. (M.) californiana has toxas in a single much smaller category of homogeneous dimensions (up to 55 µm long). C. (M.) novaezealandiae is an ill-known species, with an odd combination of microscleres, whose type appears to be lost (Bergquist & Fromont 1988, Hooper 2002). Even if the large arcuate chelae reported by Brøndsted (1924b) are deemed foreign, this species is still distinguishable from the Chilean species by its larger palmate isochelae (10–18 µm) and brownish live colour. Therefore, these species are all clearly separate from the new species, and no further listing of less conspicuous traits is necessary to sustain the argument. The new species appears thus unique among all biogeographically akin congeners sharing similar skeletal architecture.
description: Published as part of Hajdu, Eduardo, Desqueyroux-Faúndez, Ruth, Carvalho, Mariana De Souza, Lôbo-Hajdu, Gisele & Willenz, Philippe, 2013, Twelve new Demospongiae (Porifera) from Chilean fjords, with remarks upon sponge-derived biogeographic compartments in the SE Pacific, pp. 1-64 in Zootaxa 3744 (1) on pages 42-47, DOI: 10.11646/zootaxa.3744.1.1, http://zenodo.org/record/5271084