Heterogorgia abdita, Breedy & Murillo-Cruz & Cortés, 2024

Breedy, Odalisca, Murillo-Cruz, Catalina & Cortés, Jorge, 2024, A new species of Heterogorgia Verrill, 1868 (Octocorallia, Malacalcyonacea) from a mesophotic fishing shoal in the eastern Pacific, Zootaxa 5501 (4), pp. 573-582 : 575-579

Heterogorgia abdita sp. nov.

urn:lsid:zoobank.org:act:E4BEA3A4-3221-4C9D-A6D8-3DCFF5D820EE

Figures 1 –4

Material examined.

Holotype. MZUCR 4004 , ethanol preserved, Bajo Tigre , Santa Elena, La Cruz, Guanacaste, 10°57.06’N, 085°54.336’W, 45 m, G. Ampié, M. Lara and O. Breedy, 6 December 2016.

Sequences have been deposited in GenBank under accession numbers PP864465 (28S rDNA), PP873181 (mtMutS) and PP944718 (COI).

Paratype. MZUCR 4005 , data as the holotype .

Sequences have been deposited in GenBank under accession numbers PP864466 (28S rDNA), PP873182 (mtMutS) and PP944719 (COI).

Type locality. Bajo Tigre, Santa Elena, La Cruz, Guanacaste, Pacific Ocean, Costa Rica, 45 m.

Description

The holotype is a bushy colony irregularly branched, about 6.1 cm tall and 7 cm wide. The stem, 115 mm long, arises from an encrusting holdfast, 120 mm in diameter. The stem, 3.9 mm diameter, subdivides three times close to the base, with subsequent branching up to 7 times. Branches are 1–2 mm in diameter and split irregularly several times in different planes ( Fig. 1A ). The thinner branchlets are 0.8–0.9 mm diameter. The axis is horny with a chambered central core with filaments coated with hydroxylapatite ( Fig. 1B ). The polyps are totally or partially retracted into prominent, dome-shaped calyces, 1–1.5 mm height and about 1.8 mm in diameter ( Fig. 1A ). Calyces are irregularly distributed, not very close together, 0.5–3 mm apart (about 6 calyces/cm, n=30) and are more separated at the base of the colony and closer at the tips where they are in clusters of 2–4, bud-like ( Fig. 1A ). They are sparsely distributed on the holdfast ( Fig. 1B ). Polyps are preserved totally or partially retracted; they are whitish. Polyp tentacles bear tuberculate rods, 0.08–0.15 mm long and 0.016–0.03 mm wide ( Fig. 1C ). The anthocodial armature is composed of points of two to three pairs of spindles arranged en chevron, measuring 0.30–0.50 mm long and 0.03–0.05 mm wide ( Fig. 2A ). The point sclerites are bent or straight, some with a spiny distal end, and with sparse spines on the surface. The collaret is composed of two rows of spiny spindles, 0.20–0.30 mm long and 0.025 –0.035 mm wide ( Fig. 2B ). The calicular rim bears one whorl of thorns, 0.24–0.28 mm long and 0.045 –0.050 mm wide, the thorns’ shafts bearing short spines ( Fig. 2C ), and club-like sclerites, 0.12–0.20 mm long and 0.055 –0.080 mm wide, with warty tubercles and bifurcated or oval heads ( Fig. 2G ). The coenenchymal sclerites comprise various types of spindles: short and wide, with expanded warty tubercles, 0.12–0.18 mm long and 0.060 –0.085 mm wide ( Fig. 2D ), and with mostly blunt ends. Spindles are long, straight or bent, 0.13–0.40 mm long and 0.050 –0.075 mm wide, with pointed or irregular ends, one end acute and the other blunt ( Fig. 2E ); and irregularly branched spindles, 0.24–0.30 mm long and 0.06–0.08 mm wide ( Fig. 2F ). The inner coenenchyme contain small tuberculate radiates, 0.06–0.07 mm long and 0.05–0.07 mm wide ( Fig. 2I ); and warty crosses, 0.13–0.18 mm long and 0.09–0.18 mm wide ( Fig. 2H ).

The colour of the colony is white to pale yellow preserved in ethanol ( Fig. 1A ).

Variability. The paratype is a 6 cm colony branching up to four times.A small branching hydroid and a polychaete tube is attached to the colony holdfast. All other characteristics are as described for the holotype.

Habitat. The colonies were found in small clusters on large rocks mingled with branching hydroids, sponges, and bryozoans; alongside other octocoral species that are more conspicuous: H. verrucosa , Eugorgia daniana Verrill, 1868 , Muricea squarrosa Verrill, 1869 , Muricea fruticosa Verrill, 1869 , P. senta , A. osculabunda , an undescribed species of Psammogorgia Verrill, 1868 , and the black corals Myriopathes panamensis ( Verrill, 1869) , and Antipathes galapagensis Diechmann, 1941 , the latter appearing in solitary colonies close to the spot of octocorals, but making forests deeper in the shoal (Matamoros-Calderón et. al., 2021). It was not possible to photograph the colonies in situ, thus, in Fig. 3 , we show its interesting habitat.

Distribution. Only known from the type locality.

Etymology. Abditus (L), meaning hidden, concealed. The name of the coral alludes to its cryptic way of life, mingled with other small branching creatures.

Figures

FIGURE 1. Heterogorgia abdita sp. nov., holotype. MZUCR 4004. (A) Holotype, (B) SEM image of mineralized fibers of the axis; (C) tentacular rods.

FIGURE 2. Heterogorgia abdita sp. nov., holotype, MZUCR 4004, sclerites: (A) collaret spindles; (B) point spindles; (C) thorns; (D-F) spindles; (G) club-like spindles; (H) crosses; (I) radiates.

FIGURE 3. View of Bajo Tigre, 45 m in depth showing the habitat of Heterogorgia abdita sp. nov.. Photograph from video by Steven Lara and Beatriz Naranjo.