Farrea cordelli Reiswig 2020, n. sp.

Farrea cordelli n. sp.

(Figs. 4 & 5, Table 2).

Material examined. Holotype: CAS 223281, col. no. NA085-050-A, E/V Nautilus w ROVs Hercules & Argus, Dive NA085, Cordell Bank, Calif., 38.11ºN, 123.66ºW. 2119.9 m, 09 Aug. 2017.

Description. The holotype is a branching foliose sponge (Fig 4A) with a flat axis and undulating margins expanding on both sides into spoon-like projections that alternate in position on the two sides of the axis. These eventually fuse to form two series of closed tubes with distal open lateral oscula (Fig. 4B). The base attached to an overhang is dead and covered by overgrowth so its point of origin is uncertain in frame-grabs from the video made during collection but the longest branch tip is 46.3 cm from the discernable part of the base. There are two to three successive branchings; the terminal branch collected is 29.4 cm long. The axis is 1.6–2.2– 4.9 cm (n = 12) wide and interval between lateral projections/tubes is 1.3–2.1– 2.9 cm (n = 20). Lateral tubes are 1.0– 1.4–1.7 cm (n=18) by 1.4–2.6– 3.6 cm (n = 13) long; they occasionally undergo secondary branching and fuse to adjacent lateral tubes or rarely fuse to tubes of other branches of the same specimen. Terminal oscula of lateral tubes are 0.5–0.9– 1.5 cm (n = 12) in diameter. Body wall is 0.6–1.3– 1.8 mm (n = 11) thick. Color is white.

The skeletal framework is dictyonal and of the typical farreoid type, a fused lattice marginally one dictyonalium in thickness (Figs 4 C-D) with rectangular meshes. Spurs on both sides are curved towards the osculum and secondary dictyonalia are occasionally developed on the dermal side (Fig. 4E). Measurements of the framework are given at the bottom of Table 2.

* measured only on SEMs.

Megascleres are pentactins, pileate clavules and uncinates. Dermal and atrial pentactins (Fig. 5A) are similar in shape and size. A small conical knob is present on the outer center opposite the unpaired ray. Tangential rays are slightly bowed back from the tangential plane, ornamented with small microspines on the outer surface and all around the parabolic or round tips. The unpaired proximal ray is also ornamented with microspines but less densely so; its tip is rough and sharply pointed. The pileate clavules (Fig. 5B) are distributed head-out on both dermal and atrial surfaces. They are loosely grouped around the unpaired rays of surface pentactins (Fig. 4F). The heads are highly variable in size and ornamentation but only resolvable in SEM. The smallest and probably immature clavules have no marginal spines (Fig. 5b right-most). The largest have a ring of 16– 22 –30 (n = 13) large marginal spines but also indistinct rings of smaller spines both above and below the margin as well as scattered on the head. The shaft bears a dense cover of small spines on the upper third but the lower two-thirds is entirely smooth or with only occasional spines; shafts of the smallest clavules are entirely smooth. The proximal ends are bluntly pointed and entirely smooth. Uncinates (Fig. 5C) are long thin straight spicules with well developed brackets and barbs. They occur deep in the sponge near the framework, lying parallel to the main beams.

Microscleres are oxyhexasters and hemioxyhexasters. Oxyhexasters (Fig. 5D) and hemioxyhexasters (Fig. 5E) have similar basic structure; their primary and secondary rays are sparsely covered with reclined spines. Terminal rays on each primary vary from 1–7 but most commonly 2–4. Of 150 assessed, 103 (69%) are oxyhexasters and 47 (31%) are hemihexasters. Most likely there are rare oxyhexactins but none were noted.

Distribution. Known only as a single specimen from Cordell Bank National Marine Sanctuary, California, USA, collected from a depth of 2119.9 m.

Etymology. The species name, cordelli, is derived from the name of its collection location, the Cordell Bank. It is used here as a noun in apposition.

Remarks. The genus Farrea presently contains 47 valid species, 32 of which are considered recognizable. Of these, only five, F. aleutiana Reiswig & Stone, 2013, F. ananchorata Reiswig & Kelly, 2011, F. anoxyhexastera Reiswig & Kelly, 2011, F. laminaris Topsent, 1904 and F. microclavula Tabachnick, 1988, have exclusively pileate clavules and lack any other clavule type–anchorate, subanchorate, thimblate, clavate, or truncate clavules. Of these five, none have only oxy-tiped microscleres. Thus the Cordell Bank specimen represents a new species, here designated as Farrea cordelli n. sp. The pileate clavule heads are extremely small, perhaps the smallest of all Farrea species, which should allow easy recognition of other specimens of this species.