Dactylocalyx pumiceus Stutchbury 1841
Creators: name: Moser, Julia
name: Moraes, Fernando C.
name: Castello-Branco, Cristiana
name: Pequeno, Carolline B.
name: Muricy, Guilherme
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Porifera
Hexactinellida
Amphidiscosida
Dactylocalycidae
Dactylocalyx
Dactylocalyx pumiceus

description: Dactylocalyx pumiceus Stutchbury, 1841
(Figs 6–9)
Synonymy: Dactylocalyx pumiceus Stutchbury, 1841: 87; Gray 1867: 506; Carter 1873: 357; Sollas 1879: 123; Schulze 1887: 348; Reid 1957: 821; Mothes de Moraes 1977: 42; van Soest & Stentoft 1988: 10; Alcolado 2002: 55; Reiswig 2002a: 1296; Mothes et al. 2003: 63; Lopes et al. 2005: 50; Mothes et al. 2006: 58; Muricy et al. 2006: 145; Lopes 2007: 50; Hajdu & Lopes 2007: 354; Vieira et al. 2010: 21; Muricy et al. 2011: 180.
Dactylocalyx ingalli Bowerbank, 1869: 78.
Dactylocalyx pumiceus var. stutchburyi Sollas, 1879: 131.
Dactylocalyx subglobosus, Schmidt 1880: 53; Schulze 1887: 349 (non Dactylocalyx subglobosus Gray, 1867).
Diplacodium mixtum Schmidt, 1880: 57.
Dactylocalyx patella Schulze, 1886: 85.
Dactylocalyx potatorum Schmidt, 1880: 53.
Material examined. MNRJ 21299, Brazil, off Pará State, upper slope, 01°31.321’N – 046°44.231’W, 260 m depth, coll. F. Moraes / MV Alucia, submersible Deep Rover, 18.vii.2017. MNRJ 21284, Brazil, off Maranhão State, upper slope, 00°27.224’S – 043°59.429’W, 210 m depth, coll. R. Moura / MV Alucia, submersible Deep Rover, 15.vii.2017.
Material examined for comparison. Dactylocalyx pumiceus USNM 1409958, Dominica, 197 m depth, coll. B. Hoeksema, A. Schrier, B. Brandt & T. Devine, 11.iii.2016. USNM 5424, Barbados, 225 m depth, coll. A. Agassiz & C. Sigsbee, 10.iii.1879.
Diagnosis. Dactylocalyx with thick dictyonal skeleton and fused hexactins; dense small tubule network ramified and irregularly anastomosed. Megascleres asymmetrical pentactins and hexactins, both regular or with long, sinuous, filamentous rays. Microscleres discohexasters, onychohexasters and rare oxyhexasters.
Description. Basiphytous, cup- to barrel or vase-shaped, plate-like or calyciform sponge measuring 22–53 cm long by 17–30 cm wide and 23 mm thick (Fig. 6A–F). Surface microhispid, irregular, grooved in both internal and external sides and perforated by small caliber tubules (Fig. 6G). Grooves up to 3–30 mm wide and 8–50 mm deep (Fig. 6F, H). Color in vivo white, cream or greenish-yellow, becoming white or cream in ethanol. Consistency firm but friable.
Skeleton (Fig. 7): Dictyonal skeleton thick, stout to thin and fragile, tuberculated, forming polygonal meshes (mainly triangular and quadrangular with rounded corners), and with connections tip-to-tip and tip-to-node (Fig. 7A–D). Network of small tubules dense, ramified, irregularly anastomosed. Siliceous prominences project through the surface (Fig. 7A). Dermalia with fused hexactins, diactins and discohexasters.Atrialia with spined hexactins and pentactins, free or fused to the dictyonalia, diactins, and free hexasters in variable abundance (Fig. 7D).
Spicules: Megascleres are fused hexactins and free large diactins, asymmetrical pentactins and hexactins. Microscleres are discohexasters, onychohexasteres and rare oxyhexasters (Figs 7E–F, 8, 9; Table 2).
Fused hexactins irregular, asymmetrical, with straight, microspined actins 55–96 µm long by 7–10 µm thick, club-shaped, with expanded, rounded endings (Fig. 7E–F).
Large diactins smooth, crossing transversally the skeleton, always broken (not shown). Length> 350 µm, width 10.0–42.9–90.0 µm.
Pentactins asymmetrical, microspined, with tangential rays straight to curved and spines densely distributed along the rays; ends sometimes club-shaped to rounded (Fig. 8A). Longer tangential rays 58.0–148.9–390.0 µm in length and shorter tangential rays 30.0–98.0–220.0 µm in length; proximal ray 53.0–276.4–900.0 µm in length. All rays 2.5–3.2–6.3 µm thick. Some pentactins have very long, contorted rays, sometimes branching and forming long, sinuous silica filaments that may connect to the dtctyonalia (present only in MNRJ 21284; Fig. 8B).
Hexactins asymmetrical, spined, with long, straight to curved rays, that may also branch forming long sinuous filaments (Fig. 8B). Ends can be spherical to rounded (Fig. 8C). Some spicules have seven actins (heptactins; Fig. 8D). Longer tangential rays 73.0–175.8–600.0 µm in length; shorter tangential rays 23.0–111.8–360.0 µm long. Proximal ray 85.0–264.6–730.0 µm in length; distal ray 13.0–105.9–600.0 µm in length. All rays 2.5–3.8–10.0 µm thick.
Discohexasters abundant, with short spined primary rays branching in spined secondary rays that end up in umbrellas; diameter 25.0–55.0–80.0 µm (Fig. 9A).
Onychohexasters common, with short, spined primary rays branching on spined secondary rays that end up in anchors with two or three v-shaped teeth; diameter 25.0–45.9–68.0 µm (Fig. 9B).
Oxyhexasters rare, with short microspined primary rays and long microspined secondary rays, terminating in acerate ends (Fig. 9C, D); diameter 43.0–62.0–78.0 µm (n=16).
Geographical and Bathymetric Distribution. Atlantic Ocean: Portugal (Schulze 1886, 1887 as Dactylocalyx patella), Bermuda (Schulze 1887), Florida, USA (Schmidt 1880 as Diplacodium mixtum), Cuba (Schmidt 1880 as Diplacodium mixtum), Barbados (Stutchbury 1841; Schulze 1879; van Soest and Stentoft 1988), Northern Brazil (new record), Southeastern Brazil (Lopes et al. 2005), and Southern Brazil (Mothes-de-Moraes 1977), from 91 to 1966 m depth. The present record in Northern Brazil fills part of the large gap between the southernmost Caribbean records and Southeastern Brazilian specimens, noted by Lopes et al. (2005).
Ecology. Polychaetes were found associated to the sponge, which was sampled on rocky outcrop and hard carbonate bottoms at 210–260 m depth.
Taxonomic remarks. The genus Dactylocalyx contains only two species, Dactylocalyx pumiceus from Barbados and D. subglobosus Gray, 1867, probably from the West Indies, exact location unknown (Reiswig 2002a; de Voogd et al. 2021) They are very similar except by a pear-shaped body and two classes of discohexasters in D. subglobosus versus one class in D. pumiceus; onychohexasters, oxyhexasters, and irregular pentactins and hexactins with long, sinuous, filamentous rays are absent both in D. subglobosus and in most specimens of D. pumiceus (e.g., Gray 1867; Schulze 1877; Sollas 1879; Mothes-de-Moraes 1977; Reiswig 2002a; Lopes et al. 2005; Tabachnick et al. 2009). Their status as two distinct species needs verification through revision of spicule variability in the many specimens of D. pumiceus that are deposited in zoological collections worldwide (Reiswig 2002a) and additional collections for molecular studies.
The two populations studied here from Northern Brazil showed variations in body shape, color, substrate and abundance. Specimens sampled off Pará State were white in vivo, large cup- to barrel-shaped, sparse, uncommon (only three individuals were observed), and fixed to the rocky substrate by a large portion of the base or side (Fig. 6A, B). In contrast, off Maranhão State, specimens are cream to greenish-yellow in color, have lower cup- to funnel- or plate shape, are fixed on the substrate by a small area or a short peduncle, and are very abundant on hard substrates covered by a thin layer of carbonate sediments (Fig. 6 C-E). Irregular pentactins and hexactins with long filamentous rays and heptactins are present in MNRJ 21284 from off Maranhão State and absent in MNRJ 21299 from off Pará State, but we cannot extrapolate these characteristics to the whole populations without additional collections. Together, these differences could indicate that our specimens belong to two distinct species, but we described them as conspecific because they fall within the range of variation reported for D. pumiceus in the literature (Sollas 1879; Mothes-de-Moraes 1977; Reiswig 2002a; Lopes et al. 2005). Additional collections are required to further investigate this issue. We agree with Reiswig (2002a) and Tabachnick et al. (2009) that a comprehensive morphological revision of D. pumiceus is greatly needed, preferably complemented with genetic data.
description: Published as part of Moser, Julia, Moraes, Fernando C., Castello-Branco, Cristiana, Pequeno, Carolline B. & Muricy, Guilherme, 2022, Manned submersible dives reveal a singular assemblage of Hexactinellida (Porifera) off the Amazon River mouth, Northern Brazil, pp. 105-130 in Zootaxa 5105 (1) on pages 113-119, DOI: 10.11646/zootaxa.5105.1.4, http://zenodo.org/record/6332297