Erylus rhabdocoronatus, Van, Rob W. M., 2017

Van, Rob W. M., 2017, Sponges of the Guyana Shelf, Zootaxa 1, pp. 1-225: 88-90

publication ID

http://doi.org/ 10.5281/zenodo.272951

publication LSID

lsid:zoobank.org:pub:6D68A019-6F63-4AA4-A8B3-92D351F1F69B

persistent identifier

http://treatment.plazi.org/id/03A80010-7700-FFF5-FF14-A5379253FB3A

treatment provided by

Plazi

scientific name

Erylus rhabdocoronatus
status

sp. nov.

Erylus rhabdocoronatus  sp. nov.

Figures 55View FIGURE 55 a –g

Material examined. Holotype RMNH Por 9339, French Guyana, ‘Luymes’ Guyana Shelf Expedition, station 14, 6.7333°N 52.75°W, depth 76 m, bottom muddy calcareous sand, 26 August 1970GoogleMaps  .

Examined for comparison. Slide of the holotype of Erylus alleni De Laubenfels, 1934  , USNM 22268View Materials, from Puerto Rico, 68–171 m. 

Description. A fragment of a finger-shaped sponge ( Fig 55View FIGURE 55 a), 2.5 cm high and 8 mm in diameter. Color in alcohol beige, both inside and outside. Surface optically smooth, but microhispid due to being overgrown by a thinly encrusting Spirastrella  (see below); no apparent openings. Consistency firm, but fragile.

Skeleton. The usual surface skeleton is present consisting of a layer of partially overlapping aspidasters covered by a dense mass of microrhabds and carried by the cladomes of subcortical orthotriaenes. Choanosomal skeleton a largely confused mass of oxeas and a few triaenes, with bundles of oxeas traversing the choanosome.

Spicules. ( Figs 55View FIGURE 55 b –g) Oxeas, plagiotriaenes, microrhabds, aspidasters, two categories of oxyasters.

Oxeas ( Figs 55View FIGURE 55 b,b1), fusiform, curved, with sharp points, 261– 513 –648 x 14 – 21.1 –29 µm.

Ortho/plagiotriaenes ( Fig. 55View FIGURE 55 c), short-shafted; rhabdomes 204– 309 –378 x 9 – 15.3 –24 µm, cladomes 305– 371 –450 µm; cladi 163– 206 –224 x 9 – 11.6 –21 µm.

Microrhabds ( Figs 55View FIGURE 55 d,d1), curved, centrotylote, all are provided with rounded ends bearing a crown of conical spines ( Fig. 55View FIGURE 55 d1); sizes 36– 48 – 57 x 2.5– 4.1 –6 µm.

Aspidasters ( Figs 55View FIGURE 55 e,e1), oval, thin, provided with rather spaced out rosettes, 138– 148 –159 x 89 – 94 –102 µm.

Large oxyasters ( Figs 55View FIGURE 55 f), with almost smooth rays, only occasional spines, variable diameters, 19– 52 –60 µm, ray number 3–6.

Small oxyasters ( Fig. 55View FIGURE 55 g), with much more rays, but also with few spines; diameters 12– 14.6 –21 µm, ray number 9–14.

Distribution and ecology. Guyana Shelf, sandy bottom at 76 m depth.

Etymology. The name reflects the crown of blunt spines on the apices of all the microrhabds.

Remarks. The new species differs from the closest species, E. alleni De Laubenfels (1934)  in the following features—based on a comparison with a slide made from the holotype USNM 22268 and spicule measurements—(1) the aspidasters are larger (138–159 x 89 –102 µm in the present species vs. 70–114 x 30–81 µm in E. alleni  (curiously De Laubenfels gives only 70 x 35 µm); (2) the microrhabds do not have the crown of spines and are on average shorter; (3) oxeas are approximately half as thick in E. alleni  ; (4) the euaster sizes given by De Laubenfels are half the diameter (30 µm and 7 µm) of those of the new species, but re-measurement yielded sizes on average similar in both species. Perhaps De Laubenfels gave measurements of the rays. However, the shape of the rays of the larger euasters differs clearly in E. alleni  by being thinner and curved or slightly flexuous, not rigid like in E. rhabdocoronatus  sp. nov.

Mothes et al. (1999) redescribed E. alleni  and also assigned several specimens along the Brazilian coast to that species. Spicules of one of the specimens were depicted in their fig. 4 and these images appear close to those of E. rhabdocoronatus  sp. nov., especially the euasters, but there are no spines on the ends of the microrhabds, and the shape of the aspidaster is subtly broader. The larger oxyasters in Mothes et al. ’s E. alleni  are dissimilar to those seen in the slide of the holotype of E. alleni  examined here.

Van Soest & Stentoft (1988) (p. 17) reported Erylus transiens  from 100 m off Barbados, which does not conform to Weltner’s (1882) description of that species (perhaps it is E. corneus Boury-Esnault, 1973  ). These authors suggested E. transiens sensu Sollas (1888)  and E. alleni  were synonyms. According to Mothes et al. (1999: 375), followed by Muricy et al. (2011: 44), the two species differ in the possession of one ( E. transiens  ) vs. two categories of oxyasters.

The decoration of the microrhabds with crowns of spines is intermediate between entirely smooth microrhabds and those that are spined all over such as in Erylus granularis Topsent, 1904  from the Azores and Erylus soesti Mothes & Lerner, 2001  from Brazil. 

RMNH

National Museum of Natural History, Naturalis

USNM

Smithsonian Institution, National Museum of Natural History