Bomba endeavourensis Kelly, Reiswig & Samaai

Kelly, Michelle, Sim-Smith, Carina, Stone, Robert, Reiswig, Toufiek Samaai Henry & Austin, William, 2016, New taxa and arrangements within the family Latrunculiidae (Demospongiae, Poecilosclerida), Zootaxa 4121 (1), pp. 1-48 : 29-31

Bomba endeavourensis Kelly, Reiswig & Samaai gen. et sp. nov.

( Fig. 2 A, 11; Tables 5 , 8 , 9 )

Latrunculia sp. Austin & Ott 1996: 18.

Material examined. Holotype— RBCM 014-00120-001: Endeavour Ridge off British Columbia coast, Station A1448, 47.7° N, 129.217° W, 2500 m, 4 Aug 1984, collected by V. Tunnicliffe. Paratypes — RBCM 014-00120- 0 0 2, RBCM 014-00120-003, RBCM 014-00120-004, same location data.

Type location. Endeavour Ridge, British Columbia, Canada, part of a hydrothermally and seismically active area near the Juan de Fuca and Pacific tectonic plates offshore British Columbia, Canada.

Distribution. Endeavour Ridge.

Description. Tiny, low-lying, hemispherical sponges, ranging in diameter from 4–12 mm, with 2–3 long ‘horns’ arising from deep within the choanosome, projecting well beyond the surface. The choanosome of each sponge is either fully or partially detached; the sponges appear as hollow, leathery casings. Large stiff bundles of spicules protrude well beyond the surface of the sponge, forming large, conical, horn-like projections, 1–2 mm high. No oscules obvious. Colour in preservative is translucent white, mottled with reddish brown patches ( Fig. 11 A, B), composed of tiny pigmented dots at the apex of each microsclere, visible under magnification ( Fig. 11 B). A thick, dense, cross-hatch mesh of megascleres forms the leathery casing of the sponge ( Fig. 11 B).

Skeleton. Crust-like ectosome, 238 (137–414) µm thick, composed of a tangential, cross-hatched layer of megascleres on top of which is a patchy palisade of erect anisodiscorhabds. Thick, solid, compact bundles of megascleres emerge from within the choanosome, traverse the ectosome and project from the upper and lateral surfaces. Bundles are shaped like tapered horns, 2–4 ‘horns’ per specimen. Horns range in length from 1‒4 mm, and taper from 2‒7 mm at base, to a rounded point. The ectosomal crust curves up the outside of each horn for a short distance.

Spicules. Megascleres ( Fig. 11 C, D; Table 5 ), anisostyles, heads spined retrovertly (spines face away from head along shaft, flattened against shaft), spines low granular bumps in immature forms (Fig. 10D), 618 (362‒722) × 24 (17‒27) µm, n = 50.

Microscleres ( Fig. 11 E–G; Table 5 ), anisodiscorhabds with a basal whorl, a median whorl and an apical whorl, 51 (36‒57) × 38 (29‒43) µm, n = 50 ( Fig. 11 F).

Substrate, depth range and ecology. Rocky substrate, 2500 m.

Etymology. Named for the type location, Endeavour Ridge, off the coast of British Columbia, Canada.

Remarks. Bomba endeavourensis gen. et sp. nov. is highly unusual and unprecedented in the Latrunculiidae , possessing protruding ‘horns’ of megascleres, a shell-like morphology, and three-whorled anisodiscorhabds.

Figures

FIGURE 2. Distribution of North Pacific Latrunculiidae species: A. Gulf of Alaska, U. S. A and British Columbia, Canada; B. Central Aleutian Islands and Gulf of Alaska, U. S. A. Locality data for the four Kurile Island specimens of Latrunculia (Uniannulata) oparinae subgen. nov. taken from Samaai & Krasokhin (2002) and Samaai et al. (2006). L = Latrunculia, B = Bomba gen. nov.

FIGURE 11. Morphology, megascleres and microscleres of Bomba endeavorensis gen. et sp. nov.: A. Holotype RBCM 014 - 00120 - 001, paratype 1 RBCM 014 - 00120 - 002, paratype 2 RBCM 014 - 00120 - 003, paratype 3 RBCM 014 - 00120 - 004, Endeavour Ridge, British Columbia, 2500 m, scale = 5 mm; B. Enlarged details of surface showing pigmentation on apices of anisodiscorhabds and large megascleres in a cross-hatched arrangement, scale = 500 µm; C. Centrally thickened anisostyle, scale = 200 µm; D. Rounded distal and granular bumps on head of anisostyle, scale = 20 µm; E. A range of anisodiscorhabds, scale = 20 µm; F. A range of protorhabds, scale = 20 µm; G. Apex of anisodiscorhabd, scale = 20 µm.

Tables

TABLE 5. Spicule dimensions (µm) of Bomba endeavourensis gen. et sp. nov. Paratype data are from 10 spicule measurements each.

Specimen	Anisostyles	Anisodiscorhabds
RBCM 014-00120-001 Holotype	618 (362‒722) × 24 (17‒27)	51 (36‒57) × 38 (29‒43)
RBCM 014-00120-002 Paratype	669 (602–708) x 23 (20–25)	47 (39–51) x 33 (29–37)
RBCM 014-00120-003 Paratype	666 (559–721) x 21 (18–25)	55 (43–61) x 37 (34–42)
RBCM 014-00120-004 Paratype	552 (508–585) x 21 (18–23)	50 (48–57) x 41 (36–45)