Aliena parva, Breedy & McFadden & Cortés, 2023

Breedy, Odalisca, McFadden, Catherine S. & Cortes, Jorge, 2023, An enigmatic new octocoral species (Anthozoa, Octocorallia, Malacalcyonacea) from Isla del Coco National Park, ZooKeys 1169, pp. 317-331 : 317

publication ID	https://dx.doi.org/10.3897/zookeys.1169.100576
publication LSID	lsid:zoobank.org:pub:F8741794-F8DE-4D0D-B863-EB2BB8A47B0E
persistent identifier	https://treatment.plazi.org/id/11BAFF5A-A43A-46E3-AB48-95FB6986EE27
taxon LSID	lsid:zoobank.org:act:11BAFF5A-A43A-46E3-AB48-95FB6986EE27
treatment provided by	ZooKeys by Pensoft
scientific name	Aliena parva
status	sp. nov.

Treatment

Aliena parva sp. nov.

Figs 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5 , 6 View Figure 6

Materials examined.

Holotype. MZUCR 3679, lot 1, ethanol-preserved, Manuelita Afuera , Isla del Coco, 05°33.791'N, 087°02.934'W, 22 m depth, J. Cortés and M. Cruz, 4 December 2021 GoogleMaps . Paratypes. MZUCR 3680, lot 2, same data as holotype. MZUCR 3681, lot 1, lot 2, ethanol-preserved, Manuelita Canal , Isla del Coco, 05°33.524'N, 087°02.940'W, 20-30 m depth, B. Naranjo, 12 October 2021 GoogleMaps . MZUCR 3682, ethanol-preserved, Bajo Manuelita , Isla del Coco, 05°33.849'N, 087°02.676'W, 23 m, J. Cortés and A. Klapfer, 6 December 2021 GoogleMaps . MZUCR 3683, Manuelita Afuera , Isla del Coco, 05°33.791'N, 087°02.934'W, 29 m depth, O. Breedy, 28 September 2022 GoogleMaps . MZUCR 3684, Manuelita Afuera , Isla del Coco, 05°33.791'N, 087°02.934'W, 25 m depth, O. Breedy, 4 October 2022 GoogleMaps .

Type locality.

Isla del Coco, Pacific Costa Rica, at depths of 20-30 m.

Description.

The holotype is formed of 15 scattered clusters of polyps encrusting the surface of a barnacle about 4 cm in diameter; the barnacle plates are covered by many epibionts and several small, unbranched hydroids (Fig. 2A View Figure 2 ). The polyps are in clusters, 0.15-1.10 cm in longest dimension and composed of 3-20 polyps (Fig. 2A View Figure 2 ). The polyps are closely spaced; those that are preserved partially expanded are up to 2.0 mm tall (from the base to the proximal border of tentacles) (Fig. 2B View Figure 2 ). Polyps are retractile into calyces that are up to 0.75 mm in diameter, and up to 1.0 mm tall when the anthocodia is retracted. The surface of the calyx is covered by a dense layer of sclerites giving it a slightly granular appearance. The tentacles are transparent with yellow sclerites. When retracted, the yellow sclerites can be observed at the polyp-mound summit (Fig. 2C View Figure 2 ). The coenenchyme is thin and without differential sclerite layers; it extends over the substrate. Coenenchymal sclerites are asymmetrical spindles with variable ends: pointed, blunt, bifurcated, or a combination (Figs 4 View Figure 4 , 5 View Figure 5 ). They are straight or slightly curved, 0.16-0.35 mm long, and 0.02-0.08 mm wide (Figs 4A View Figure 4 , 5A View Figure 5 ), with simple tubercles, not very crowded on the surface; they do not have complex tubercles or waists. Anthocodial sclerites are mostly red flat rods, 0.20-0.30 mm long and 0.02-0.06 mm wide, with serrated or prickly borders and sparse thorns on the surface, and smaller biscuit-like rods, 0.06-0.10 mm long and 0.02-0.03 mm wide (Fig. 4C View Figure 4 , 5B View Figure 5 ). Anthocodial rods are arranged ' en chevron ', forming points but not a collaret (Fig. 2B View Figure 2 ). The flat rods are arranged in longitudinal rows along the polyp body (Fig. 2B View Figure 2 , 5D View Figure 5 ). Tentacular sclerites are spine-like rods with a bent end 0.14-0.29 mm long and 0.02-0.03 mm wide (Figs 4B View Figure 4 , 5C View Figure 5 ).

Colonies are dark red in life and when preserved (Fig. 2A-C View Figure 2 ). Coenenchymal sclerites are mostly dark red, but sometimes with lighter hues (Fig. 4A View Figure 4 ). The characteristics of the paratypes are very consistent with those of the holotype.

Remarks.

The colonies are overgrowing dead or live substrates, encrusting small rocks, barnacle plates, shells, or among turf. They were frequently found among the worm tubes occupied by the endemic fish Acanthemblemaria atrata Hastings & Robertson, 1999 from Isla del Coco (Figs 3C View Figure 3 , 6B View Figure 6 ). When polyps are fully expanded, the gastric cavities of the polyps extend high over the polyp mounds, and the oral disk prolongs into eight rays marked by small, red rods along the intertentacular margins (Figs 3B-D View Figure 3 , 6A View Figure 6 ). We noticed during the January 2022 and September-October 2022 trips that the polyps have one tentacle that is opaque and appears to be somewhat swollen at its base (Fig. 6A, B View Figure 6 ). This differentiated tentacle was not present in the colonies observed during the other trips in 2021. Reasons for this difference and possible functions of this differentiated tentacle remain unknown.

Distribution.

Colonies were found at various localities north of Isla del Coco around Manuelita Afuera, Manuelita Canal and Bajo Manuelita; and northwest at Roca Sucia, 05°32.875'N, 087°04.956'W and Viking Rock (Isla Cáscara), 05°33.006'N, 087°03.865'W, NW of the island (Fig. 1 View Figure 1 ). Only known from the type locality. The bathymetric range was 20-30 m.

Etymology.

Parvus (L), in allusion to the small size of the polyps. Gender feminine: Aliena parva .