Cirrhipathes cf. spiralis ( Linnaeus, 1758 )

Terrana, Lucas, Bo, Marzia, Opresko, Dennis M. & Eeckhaut, Igor, 2020, Shallow-water black corals (Cnidaria: Anthozoa: Hexacorallia: Antipatharia) from SW Madagascar, Zootaxa 4826 (1), pp. 1-62 : 37

Cirrhipathes cf. spiralis ( Linnaeus, 1758)

Fig. 21

Gorgonia spiralis Linnaeus 1758, p.800

Antipathes spiralis Pallas 1766, p.217

Cirripathes spiralis Brook 1889, p.85 , pl.7, fig.10

Cirripathes (Eucirripathes) spiralis van Pesch 1914, p.158 , figs 216–241

Cirrhipathes spiralis Utinomi 1956, p.181 , fig.3

Material examined. Toliara, 25 m. Distal fragment, specimen INV.131371 .

Depth range. 15–25 m.

Description. The colony has tight dextral helicospirals, which start coiling at about 3 cm from the base before being spaced apart by an average of 1.2 cm ( Fig. 21 , a). The coils are not always regular and can be slack in some colonies ( Fig. 21 , b, c). The specimen from which the sample was collected measures about 50 cm in height and the coils are about 1 cm in diameter. The skeleton diameter is about 3 mm at base and tapers slightly at top. The colony is bright or light yellow with yellow to orange polyps ( Fig. 21 , a–c). The polyps are found all around the stem with the exception of the inner side of the coils ( Fig. 21 , b, c) and they measure up to 2 mm in transverse diameter. Polyps are irregularly spaced, and the interpolypar distance can reach 3.5 mm, sometimes resulting in large areas of exposed coenenchyme ( Fig. 21 , b, c). They have a prominent oral cone and the transverse canals are clearly visible ( Fig. 21 , b). The tentacles appear long and pointed when fully extended ( Fig. 21 , c). Because of the great variation in the interpolypar distance, the number of polyps per cm is very different across the colony.

The inner and outer spines near the top of the corallum have the same morphology but differ in length. Spines are conical, straight or slightly curved, papillose with a blunt apex which is slightly knobbed ( Fig. 21 , d–f). They stand either at a right angle to the corallum or are slightly inclined ( Fig. 21 , d). Spines are arranged in spirals, and up to ten longitudinal rows can be seen on a section 1.9 mm in diameter ( Fig. 21 , d). The outer spines measure 0.20–0.26 mm in height while the inner spines are 0.16–0.21 mm in height. The spine spacing ranges from 0.15 to 0.7 mm.

Taxonomic remarks. This species was described based on pre-Linnean descriptions, without any type specimen. It was reported as Acarbarium anguinum in 1685 and then as Palmijuncus anguinus in 1750 by Rumphius (see Bayer 1959) before being mentioned in the 10 th edition of the Systema Naturae in 1758 by Linnaeus under the name Gorgonia spiralis (see Brook 1889). It was latter mentioned under Antipathes spiralis by Pallas (1766), before being moved to the new genus Cirrhipathes by Blainville in 1834. It is the type species of Cirrhipathes . The description by Pallas (1766) mentions a distribution in Norway, the Mediterranean Sea and the Indian Ocean. However, as mentioned by Lamouroux (1824), the two first locations might be for other species. Detailed descriptions of this species were made by Brook (1889) and van Pesch (1914). Brook (1889) refers to tall colonies, with a tapering stem and dextral, tight coils, 1.5 cm in diameter. Brooks (1889) notes a somewhat spiral arrangement of spines, forming 10–11 rows, and indicates that spines are conical, blunt, and 0.3 mm long on the polypar side. Van Pesch (1914) gives a more detailed description of polyps and highlights a certain variability in spine size, shape and ornamentation, resulting in four variants, some of which have distinctly tuberculated and papillose tall spines. The present specimen shows a high affinity with Brook’s (1889) description but given the lack of a neotype and the limits of the description, it is identified as Cirrhipathes cf. spiralis . It is possible that environmental plasticity, age and region of the stem may cause high variability of the characters.

Distribution. Indian Ocean ( Pallas 1766), Indonesia ( Ellis & Solander 1786; van Pesch 1914; Wagner et al. 2011), Korea ( Moon & Song 2008), Hawaii ( Clarke et al. 2015), Madagascar (present study).

Genus Stichopathes Brook, 1889

The genus Stichopathes encompasses unbranched corals but they differ from Cirrhipathes in having polyps arranged in a single row on one side of the corallum; the polyp row can sometimes twist around the stem. Even if the homology of this character has been questioned by several authors ( Pasternak 1977; Bo et al. 2012a), it remains the only character for the distinction of this group. Like Cirrhipathes species, Stichopathes species can be straight, slightly to highly contorted, curved or coiled. The spines are smooth, papillose or with tubercles; the presence of secondary spines is common. To date, this genus encompasses 36 accepted species, of which Stichopathes pourtalesi Brook, 1889 from the Caribbean is the type species ( Bo & Opresko 2015; Molodtsova & Opresko 2020). The type specimens have been lost for eight of the currently accepted species, and 12 of the currently accpeted species were described from the Indian Ocean.

Figures

FIGURE 21. Cirrhipathes cf. spiralis (Linnaeus, 1758). (a) In situ picture of the specimen INV.131371 with well-defined coils. (b–c) In situ pictures of other phenotypes with loose spirals. (d) Section 1.9 mm in diameter of the distal part of the colony pictured in (a). (e) Inner spines which are papillose, conical with a blunt tip slightly knobbed. (f) Longer straight outer spines having the same morphology as the inner spine.