Muricea subtilis, Breedy, Odalisca & Guzman, Hector M., 2016

Breedy, Odalisca & Guzman, Hector M., 2016, A new Muricea species (Cnidaria, Anthozoa, Octocorallia) from the eastern tropical Pacific, ZooKeys 629, pp. 1-10 : 3-6

Taxon classification Animalia Alcyonacea Plexauridae

Muricea subtilis sp. n. Figures 1, 2, 3

Material.

Holotype: UCR 2322 (URR 46), ethanol preserved, off Esterillos, Puntarenas, Central Pacific, Costa Rica, 09°20.940'N, 84°30.240'W - 09°21.242'N, 84°30.043'W, 51.7-53 m, R. Vargas, R/V Urraca, 17 July 2016. UCR 2322A, fragment for molecular analysis in progress.

Paratypes: MZUCR-OCT 0082 (URR 44), ethanol preserved, off Punta Mala, Puntarenas, 09°22.085'N, 84°32.206'W - 09°22.280'N, 84°32.037'W, 44.2-44 m, R. Vargas, 17 July 2005; MZUCR-OCT 0125 (URR 26-53), dry, off Carrillo Beach, Nicoya, Guanacaste, 09°51.264'N, 85°29.37'W - 09°50.727'N, 85°29.37'W, 39-40 m, R. Vargas, R/V Urraca, 16 July 2005; MZUCR 0126 (TWL 27-36), dry, off Carrillo Beach, 09°50.013'N, 85°29.476'W - 09°49.88'N, 85°29.40'W, 30-32 m, R. Vargas, R/V Urraca, 16 July 2005; MZUCR 0140 (URR 47), dry, off Esterillos, 09°20.212'N, 84°28.358'W - 09°21.610'N, 84°28.275'W, 51.7-53 m, R. Vargas, R/V Urraca, 17 July 2016; UCR 2321 (URR 46), as the holotype.

Type locality.

09°20.940'N, 84°30.240'W (off Esterillos, Puntarenas), 53 m in depth.

Diagnosis.

Colonies spiny and delicate in appearance, fan-like or lateral. Branching irregular, mostly dichotomous, in one or two planes. Branches and branchlets thin, 1.5-2 mm in diameter, in some cases thinner, about 1 mm. Some branch pseudo-anastomosis present. Polyps mostly close together. Calyces shelf-like, prominent, up to 1.2 mm. Calyces not imbricate. Coenenchyme thin. Coenenchymal and calycular sclerites mostly leaf-like spindles up to 0.95 mm long. Anthocodial sclerites mostly irregular warty rods and thin torches, translucent or whitish. Colony colour whitish to pale yellow.

Description.

The holotype is a 14.5 cm tall and 23 cm wide colony. A 15 mm long stem, 6 mm in diameter, subdivide in two main branches, 4-5 mm diameter and arise from an irregular, 15 mm diameter holdfast (Figure 1A). The branches are about the same diameter at the bottom of the colony 3-4 mm producing thinner branchlets 2-3 mm diameter up to the ends. Branching is irregular, mostly dichotomous, branches and branchlets project at angles 45°-75°and separated up to 25 mm. They spread in one plane in a fan-like colony. The branchlets are straight or curved inwards, some are anastomosed. Unbranched terminal ends are about 2 mm in diameter and up to 40 mm long. The axis is amber. The calyces are shelf-like, 1-1.2 mm long, giving a spiny appearance to the colony. They are close together, or only a few millimetres apart, 0.5-1.5 mm, and not imbricate (Figure 1B). Some branches are devoid of polyps, probably eaten by worms. Polyps are on the upper side of the elongated calyces. The calyx size and spacing vary from the larger branches to the thinner, being larger and acute, and closer placed at the branchlets and shorter, and distant at the main branches and almost absent at the stem. The coenenchyme is thin, composed of whitish and translucent sclerites, mostly of various kinds of spindles (Figure 2 A–C). The coenenchyme and the calycular sclerites are mostly leaf-like spindles, 0.25-0.93 mm long, and 0.09-0.20 mm wide and spindles, 0.40-0.60 mm long and 0.06-0.10 wide (Figure 3 A–C). The axial sheath is composed of spindles, 0.25-0.45 mm long and 0.04-0.07 mm wide (Figure 3D). The anthocodial sclerites are translucent irregular warty rods, thin torches, irregular short spindles, 0.05-0.2 mm long, and 0.01-0.05 mm wide (Figures 2D, 3D). The colony is whitish to pale yellow (Figure 1 A–B).

The paratypes agree in all characters with the holotype; however, some colonies have thinner branchlets, about 1 mm in diameter, and the leaf-like spindles can reach 0.95 mm long.

Etymology.

The adjective subtilis (L) meaning fine, thin, delicately slender, of a cutting edge, is used here, in allusion to the thin and spiny branches characteristic of the species. The term subtilis in literature combines sharpness and acuteness that imply clarity which could also evoke the white colour of the colony.

Habitat and distribution.

The species has been collected from muddy-sand bottoms, together with other octocoral species such as Muricea fruticosa Verrill, 1869; Pacifigorgia senta Breedy & Guzman, 2003, and other invertebrates from 30 to 54 m deep. A few species of gorgonians were the dominant component of the catches; some specimens were attached to debris or shells that probably hold the colonies on the mud-sandy substrate. Muricea subtilis sp. n. was collected along the outer part of Nicoya Gulf and central Pacific coast of Costa Rica.