Chondrocladia (Chondrocladia) Thomson, 1873

Subgenus Chondrocladia (Chondrocladia) Thomson, 1873 View in CoL

Diagnosis: Chondrocladia without a layer of special spicules (spear-like tylostyles or trochirhabds), lacking special rostriform (snoutlike) subtylostyles in filaments or terminal balls, and without planar vanes formed of evenly spaced upright branches ( Lee et al. 2012).

Chondrocladia (Chondrocladia) trisigmata sp. nov. ( Fig. 4 View Fig ) urn:lsid:zoobank.org:act:ABEFBD2A-55AC-4051-B5FE-50E7FA873FFF

Material examined: Holotype. MNRJ 16000 View Materials , continental rise to the south of the Vitória-Trindade seamounts’ chain, off SE Brazil, Southwest Atlantic ( R / V ‘ Marion Dufresne ’ MD-55 Expedition, Stn. 8 CP17, -21.134 / -38.4349), collection method: dredge, 3250– 3270 m depth, coll. N. Boury-Esnault, 11.V.1987. GoogleMaps

Diagnosis: The only Chondrocladia (Chondrocladia) species with three categories of sigmas.

Description: Massive, rounded; smooth surface with scattered circular structures. No projections seen. Specimen in fragments ( Fig. 4A View Fig ), the biggest one 12 × 12 mm in area and 5 mm thick. Compressible consistence, rough and easy to tear. Color beige in ethanol.

Skeleton: Ectosomal skeleton with a layer of organic material, megascleres type II and microscleres arranged irregularly. Choanosomal skeleton with an irregular reticulation of megascleres just below the ectosome, and ascending tracts of styles I with microscleres randomly scattered in the body fragment analyzed.

Spicules: Megascleres are two size categories of styles. Styles I ( Fig. 4C View Fig ), smooth, fusiform, one end rounded and the other tapering gradually, conical or hastate; 1287–2126.9–3318 × 19–32.8–50 µm. Styles II ( Fig. 4D View Fig ), smooth, straight with one end rounded and the other hastate to conical; 378–1000.7–1232 × 14–18.6–22 µm. Microscleres are two categories of anchorate isochelae, and three categories of sigmas. Isochelae I ( Fig. 4E View Fig ), smooth, long shafted, tridentate with pointy alae, 65–82.2–98 µm long. Isochelae II ( Fig. 4F View Fig ), smooth tridentate with pointy alae, 37–42–50 µm long. Sigmas I ( Fig. 4G View Fig ), slender, tapering gradually to sharp ends, 77–90.5–96 µm long. Sigmas II ( Fig. 4H View Fig ), similar to sigmas I, but shorter, 22–28.2–36 µm long. Sigmas III ( Fig. 4I View Fig ), C-shaped, markedly fusiform, with central part bearing lateral fimbria-like expansions, 9.6–10.8–13 µm long.

Distribution and Ecology: Known only from its type locality, the continental rise to the south of the Vitória-Trindade seamounts chain region (SW Atlantic), at 3250–3270 m depth.

Etymology: The specific epithet, trisigmata , is used as a noun in apposition, and refers to the three categories of sigmas present in the new species, a distinguishing feature within its subgenus.

Remarks: Although these fragments, at first look, do not look like a carnivorous sponge, the specimen was dredged in 1984 on board of the R/ V ‘ Marion Dufresne ’, it is very common to receive damaged specimens or even only fragments. After careful analyzes of its peculiarities on the surface, plus skeleton and spicule set, we were convinced of its classification. Chondrocladia (Chondrocladia) presents 34 valid species distributed worldwide ( Ekins et al. 2020; de Voogd et al. 2022). The new species differs from its congeners by the presence of three categories of sigmas (see comparative table including data from all species from every other subgenus, table 10 in Ekins et al. 2020). Chodrocladia (C.) antarctica Hentschel, 1914 and C. (C.) concrescens ( Schmidt, 1880) (sensu Hestetun et al. 2016b) were originally reported with two categories each of styles, isochelae and sigmas, however, both species do not present a third category of sigmas (similar to the sigmoid isochelae of Monanchora arbuscula ), an apomorphy of the new species. Further distinctness is apparent from a detailed analysis of spicules’ shape and micrometries. Both formerly known species have sigmas that can reach considerably larger dimensions (143–165 µm, and 69–97 µm, respectively; cf. Göcke and Janussen 2013; Topsent 1920). In the case of C. (C.) concrescens , isochelae I can also be much larger (110–130 µm) and have six teeth, while isochelae II differ markedly in their bird-cage shape plus four to six teeth ( Topsent 1920, fig. 3b; Hestetun et al. 2016b, fig. 7D).

New taxonomic combinations

In order to clarify some questions pointed in other studies related to Echinostylinos species (e.g., see Carvalho et al. 2016; Vacelet and Kelly 2022), taxonomic revisions are needed and two new combinations are proposed below: