INTRODUCTION
Leptogorgia Milne-Edwards & Haime, Reference Milne-Edwards and Haime1857 (Gorgoniidae) is a widespread genus, and one of the most abundant throughout most of the eastern Pacific. Twenty-one species of the genus from shallow waters (>50 m) have been recognized as valid (Breedy & Guzman, Reference Breedy and Guzman2007) and 16 of them are reported for Panama. Nine of these species occur in the Gulf of Chiriquí where three are abundant and widely distributed, i.e. Leptogorgia alba (Duchassaing & Michelotti, Reference Duchassaing and Michelotti1864), L. cofrini Breedy & Guzman, Reference Breedy and Guzman2005, and L. rigida Verrill, Reference Verrill1864. The occurrence of the other seven species of Leptogorgia reported for Panama were not confirmed by our recent explorations of the Pearl Islands (Gulf of Panama) and the Gulf of Chiriquí; they are known only from type material. Gorgonians in general, but especially species of Pacifigorgia Bayer, Reference Bayer1951 and Leptogorgia, represent the main faunal component in several shoals around Coiba Island (Guzman et al., Reference Guzman, Guevara and Breedy2004; Guzman & Breedy, Reference Guzman and Breedy2008).
Distinction among species of Leptogorgia, as in most gorgoniids, is based on morphological criteria, colony growth form, colour, and sclerites (Grasshoff, Reference Grasshoff1992; Breedy & Guzman, Reference Breedy and Guzman2007). The growth forms of the eastern Pacific species show a large range of variation, including dichotomous, pinnate, and bushy; branching in one plane or several planes, fragile or stout (Breedy & Guzman, Reference Breedy and Guzman2007). Several groups of species can be determined just for the growth form, but the combination of the growth form, coloration, and polyp sculpture and arrangement, which is evident in living and preserved specimens, is much more significant than the growth form alone. External differences among species of Leptogorgia lead us to divide the 21 valid species into three species groups (based on Breedy & Guzman, Reference Breedy and Guzman2007). The ‘pumila-group’, consisting of nine species, have prominent polyp-mounds, pinnate branching and coloured colonies; the ‘alba-group’ consists of five species, with flat or slightly raised polyp-mounds, pinnate or dichotomous branching and white colonies; and the ‘rigida-group’ consists of the remaining seven species, with flat polyp-mounds, branching variable and coloured or bicoloured colonies. The new species belongs to the pumila-group.
Herein, we describe Leptogorgia christiae sp. nov., which is presently known at the type locality Roca Hacha, south-west Coiba Island, as well as its relationship with the other species in the genus reported for Panama.
MATERIALS AND METHODS
The holotype was collected by SCUBA diving, down to 30 m in depth at Roca Hacha, Gulf of Chiriquí. It was air-dried. Sclerites were prepared for light and scanning electron microscopy (SEM) following the standard techniques for structural analysis (Bayer, Reference Bayer1961; Breedy & Guzman, Reference Breedy and Guzman2002). The holotype is deposited in the Museo de Zoología, Universidad de Costa Rica (UCR), Costa Rica, and a fragment is kept at the Smithsonian Tropical Research Institute (STRI), Panama. The ‘species-group’ concept used in this study was adopted from Grasshoff (Reference Grasshoff1988, Reference Grasshoff1992), but without geographical considerations. Consequently, ‘species-group’ here refers to a number of species of octocorals that share similar external characteristics.
Type material
Holotype: Colony dry (Roca Hacha, Gulf of Chiriquí, Panama; water depth: 30 m) [UCR 1733 (STRI 1006)] Collected by H.M. Guzman, 27 July 2006. Fragment dry (Roca Hacha, Gulf of Chiriquí, Panama; water depth: 30 m) [STRI 1006] Collected by H.M. Guzman, 27 July 2006.
Etymology
This species is named in honour of Mrs Christy Walton marine enthusiast and supporter of biodiversity conservation in North America and the tropics. Mrs Walton and her husband Mr John Walton have encouraged scientific research, institutional and community development, and the creation of new protected areas in sensitive marine ecosystems for many years.
Diagnosis
Stiff, flabellate, light orange colony. Growth form upright, branching pinnate, 4–6 times. Anastomosis absent. Polyps sparsely placed all around branches, fully retractile. All sclerites light orange and mostly asymmetric capstans, and blunt spindles. Few spindles have acute ends. Largest spindles reach up to 0.12 mm in length. Anthocodial rods flat, up to 0.08 mm in length.
Description
Colony erect and uniplanar, 8.2 cm in height and 6.3 cm in width, arising from a laminar holdfast partially covered by coenenchyme, but devoid of polyps (Figure 1A). Stem, 3 mm in diameter extends 1.5 cm and subdivides in two branches, 2–3 mm in diameter, which diverge and subdivide up to 6 times in the same pinnate manner producing a small, flabellate, strong fan (Figure 1A&B). Branches are flattened in cross-section; they reach up to 2 mm in diameter. Unbranched terminal twigs reach up to 5 mm in length and 1 mm in diameter; tips are blunt. Polyps are distributed all around the branches and sparsely placed. Polyp-mounds are prominent and conical, with slit-like apertures (Figure 1B). Colour of the colony, sienna when alive, and fading sienna in the dry specimen. Sclerites of the coenenchyme are all light orange. They are mostly blunt spindles and capstans (Figure 1C). Capstans reach up to 0.9 mm in length and 0.04 mm in width, they are strongly tuberculate (Figure 2). Spindles are mainly blunt at the ends with a dominance of irregular forms with one end elongated composed of 2 or 3 whorls of warts, and the other with one or two; they reach up to 0.12 mm in length, and 0.05 mm in width (Figure 2). In most of the spindles, the warts are close together and the diameter of the whorls does not exceed much the diameter of the sclerite axes. Several sclerites have a characteristic bent end. Spindles with acute ends are not abundant, they can reach up to 0.13 mm in length and 0.04 mm in width, and are slightly curved (Figure 2). A small number of warty crosses are also present, up to 0.07 by 0.07 mm in size (Figure 2). Anthocodial sclerites are of the same light orange hue, somewhat flattened rods, up to 0.08 mm in length, and 0.02 mm in width, with wavy borders, or with lobed-like marginal projections (Figure 2, bottom right).
Leptogorgia christiae sp. nov. (A) holotype [UCR 1733 (STRI 1006)]; (B) detail of colony branch; (C) SEM coenenchymal sclerites.
SEM sclerites of Leptogorgia christiae sp. nov., holotype [UCR 1733 (STRI 1006)].
Habitat
The new species is very scarce and it was found at 15–30 m depth, on exposed rocks, mixed with other octocorals species, and sponges. It has been found only at the type locality, Roca Hacha, where few scattered specimens were observed but not collected; despite this it is one of the most diverse spots around Coiba Island with about 17 species of octocorals living in a small area exposed to currents and strong swell.
Distribution
Only known from Roca Hacha, Gulf of Chiriquí, Panama (type locality).
DISCUSSION
According to the branching pattern, which is pinnate, and the prominent polyp-mounds, this species belongs in the pumila-group composed of Leptogorgia pumila (Verrill, Reference Verrill1868), Leptogorgia diffusa (Verrill, Reference Verrill1868), Leptogorgia florae (Verrill, Reference Verrill1868), Leptogorgia labiata Verrill, Reference Verrill1870, Leptogorgia parva Bielschowsky, Reference Bielschowsky1929, Leptogorgia regis Hickson, Reference Hickson1928, and Leptogorgia taboguilla (Hickson, Reference Hickson1928). All reported for Panama and Leptogorgia aequatorialis Bielschowsky, Reference Bielschowsky1929 and Leptogorgia obscura Bielschowsky, Reference Bielschowsky1929, only reported for Ecuador. The differences are described in Table 1. The new species is different from the others especially in the style of branching. It branches up to six times, which differs from all the others that branch 3 or 4 times. Leptogorgia christiae grows basically in one plane, as is the case in L. diffusa and L. florae, but these two species have thin branches and the colonies have a delicate appearance; L. christiae sp. nov. has thicker branches, and the colony is stout. In addition, the dominant type of sclerites in L. diffusa and L. florae is the spindle while in L. christiae it is the capstan.
Comparative features for Leptogorgia species in the pumila-group.
Colours: dark orange (do), light orange (lo), light yellow (ly), orange (o), pink (p), purple (pu), red (r), reddish purple (rpu), sienna (s), yellow (y), white (w).
Branching tendency: multiplanar (m), uniplanar (u).
Dominant type of sclerites: capstan (c), spindle (s).
The new species is different from the others by the combination of characters of having a conspicuous branching pattern that reaches up to six subdivisions, growing basically in one plane, showing a strong aspect, and by having mainly asymmetrical sclerites, sclerites with bent ends, spindles with curved axes, and monochromatic sclerites.
Unfortunately, it is not possible to make further specimen comparison since only one specimen was available for examination. However, we have noticed that the species in the ‘pumila-group’ are very consistent and show low intraspecific variation (Breedy & Guzman, Reference Breedy and Guzman2007).
ACKNOWLEDGEMENTS
We are grateful to Phil Alderslade (Museum and Art Gallery of the Northern Territory, Darwin), Leen van Ofwegen (National Museum of Natural History Naturalis, Leiden), Gary Williams (California Academy of Sciences, San Francisco) and Stephen Cairns (NMNH) for critical review of the manuscript. We thank Carlos Guevara, and crew members from RV ‘Urracá’ for their invaluable help in the fieldwork. We are grateful to Enrique Freer (Centro de Investigación en Estructuras Microscópicas, UCR) for providing the SEM facilities and Percy Denyer (UCR) for making the figures. This project was partially sponsored by the Smithsonian Tropical Research Institute, The Nature Conservancy, and Conservation International. We thank the Government of Panama for providing the permits to collect and work in the country and marine protected areas.
