Farrea hieroglyphica Tabachnick & Fromont, 2019

Tabachnick, Konstantin, Fromont, Jane, Ehrlich, Hermann & Menshenina, Larisa, 2019, Hexactinellida from the Perth Canyon, Eastern Indian Ocean, with descriptions of five new species, Zootaxa 4664 (1), pp. 47-82 : 61-64

Farrea hieroglyphica Tabachnick & Fromont sp. nov.

urn:lsid:zoobank.org:act:7FCB8331-26A8-4852-B8CE-5A3647E171AE

Material examined. Holotype ( WAM Z92521). Australia: Western Australia: 1 specimen, Perth Canyon, Site E (31 o 46’19.884’’S, 114 o 42’21.144’’E, Figure 1 ), 1357 m, A. Hosie, ROV, 07/03/2015, RV Falkor station FPC15_D05_ S006 . Paratype ( WAM Z88475). Australia: Western Australia : 1 specimen, Perth Canyon, Site E (31 o 46’19.884’’S, 114 o 42’21.144’’E), 1357 m, A. Hosie, ROV, 07/03/2015, RV Falkor station FPC15_D05_S006 .

Body, Figure 11 . Erect stock of branching tubes with basal plates. Sponge body tapers to basal plate. Two speci- mens: paratype was attached to a cnidarian fragment. Holotype dimensions: height 60 mm, width at widest point apically 30 mm to base 5 mm, wall thickness 5 mm. Fine reticulate skeleton visible beneath tissue. Texture soft, surface smooth and microhispid, colour creamy white.

Framework, Figure 12 . The wall is constructed from a single layer of farreoid skeleton with rectangular meshes 0.33–0.40x 0.52–0.81 mm, constructed from beams 0.020 –0.030 mm in diameter.

Spicules. Megascleres, Figure 13 . Uncinates, about 2.1/ 0.006 mm, are very rare ( Figure 13 B ). Dermalia and atrialia are pentactins ( Figure 13 A ) with the tangential ray slightly bent toward the ray directed inside the body. These tangential rays have spines directed outside the body, and small spines distributed in all directions at distal parts of the rays. The ray directed inside the body has spines at the base and in the distal part, close to the outer end, with the outer ends of these spicules being rounded. The tangential rays of dermal and atrial pentactins are 0.153 –0.378 mm long (n=25, avg: 0.240 mm, std: 0.053 mm), the ray directed inside the body is 0.142 –0.443 mm long (n=25, avg: 0.275 mm, std: 0.087 mm), the diameter of these rays is 0.007 –0.012 mm. Clavules are represented by two types: pileate and anchorate ( Figure 13 C–I). Pileate clavules are 0.336 –0.537 mm long (n=25, avg: 0.443 mm, std: 0.054 mm), the disc is 0.007 –0.018 mm long (n=25, avg: 0.015 mm, std: 0.003 mm) and 0.030 –0.042 mm in diameter (n=25, avg: 0.036 mm, std: 0.004 mm). Anchorate clavules often have irregular spines along the shaft, similar to the tooth of the anchor. At times the number of teeth on the anchor are so reduced that the entire anchor becomes asymmetrical. Anchorate clavules are 0.266 –0.885 mm long (n=25, avg: 0.437 mm, std: 0.126 mm), the anchor is 0.024 –0.077 mm long (n=25, avg: 0.045 mm, std: 0.013 mm) and 0.041 –0.091 mm in diameter (n=25, avg: 0.061 mm, std: 0.015 mm).

Microscleres, Figure 13 . Microscleres are represented by numerous abnormal hieroglyph-like forms derived from discohexactins and hemidiscohexasters by reduction of the rays. The forms with no secondary rays (descendants from hemidiscohexasters and discohexactins) are very rare. Most common are discoidal stauractins, tauactins and diactins (amphidiscs), sometimes with curved rays ( Figure 13 J–W). These discoidal spicules have rays 0.003 –0.020 mm long (n=25, avg: 0.012 mm, std: 0.004 mm), the primary ray, when present, is 0.003 –0.011 mm long (n=8, avg: 0.007 mm, std: 0.003 mm).

Remarks. The new species has a very specific complement of discoidal microscleres which have a very irregular form (hieroglyph-like), including amphidiscs. These hieroglyph-like spicules are unique for the species. However, the presence of teeth-like spines on the shafts of anchorate clavules is not a specific character as similar spicules have been observed in F. aculeata Schulze, 1899 , F. convolvulus Schulze, 1899 , F. mexicana Wilson, 1904 , F. beringiana and F. beringiana kurilensis Okada, 1932 , F. lendenfeldi Ijima, 1927 , F. nodulosa Ijima, 1927 , F. medusiforma Reiswig & Kelly, 2011 , F. raoulensis Reiswig & Kelly, 2011 and rare spines were found on anchorate clavules in F. nodulosa Ijima, 1927 and F. herdendorfi Duplesis and Reiswig, 2004 .

Etymology. The species name refers to the similarity of the discoidal microscleres to oriental hieroglyphs, which are unique to this species.

Distribution. Currently found only in the Perth Canyon at 1357 meters depth.

Figures

FIGURE 1. Map of Perth Canyon. Triangles are RV Falkor stations and circles are RV Southern Surveyor stations.

FIGURE 11. Farrea hieroglyphica, sp. nov., paratype, WAM Z88475 and holotype, WAM Z92521, external morphology (scale 50 mm).

FIGURE 12. Farrea hieroglyphica, sp. nov., holotype, WAM Z92521, SEM images. A, B, one layer of farreoid skeleton together with dermal pentactins and clavules. C, loose spicules: pileate and anchorate clavules and rays of dermal pentactins. D, anchorate clavules and some irregular discoidal microscleres.

FIGURE 13. Spicules of Farrea hieroglyphica, sp. nov., holotype, WAM Z92521. A, dermal pentactin. B, uncinate. C–G, anchorate clavules. H–I, pileate clavules. J–M, micramphidiscs. N, microstaurodisc. O–R, microtaudiscs. S–W, other abnormal discoidal microscleres.