Stichopathes cf. maldivensis Forster Cooper, 1903

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 : 40-42

Stichopathes cf. maldivensis Forster Cooper, 1903

Fig. 23

Stichopathes maldivensis Forster Cooper 1903 , pl. 45, fig. 4

Material examined. Toliara, 17 m, 24 m. Distal fragments of two colonies, specimens INV.131372 and INV.131370 .

Depth range. 15–52 m.

Description. Colonies may be either straight and slightly sinuous ( Fig. 23 , a), may have very loose apical coils or not (up to 1.6 m tall, 7.5 mm in basal diameter; Fig. 23 , b, c) or with more evident apical large loops (up to 5 m tall, 8.5 mm in basal diameter). The colonies can show a branched pattern which is the consequence of a breaking event ( Fig. 23 , b). The coral is white or orange-brownish with the polyps in a single row occasionally twisting around it ( Fig. 23 , d, e). Polyps are crowded with six polyps per cm and measure 1.5-3.0 mm in transverse diameter, but very small polyps can be found irregularly between the larger ones ( Fig. 23 , d, e). There is no interpolypar space. The oral cone is prominent, and the tentacles are thick. When they are expanded during the night, they are long and finger-like ( Fig. 23 , e).

Two types of spines are found ( Fig. 23 , f–j). On a distal fragment measuring 4.45 mm in diameter, about 10–11 longitudinal rows of primary spines are visible from one aspect ( Fig. 23 , f). The primary spines are tall, cylindrical and disposed at a right angle to the stem on the polypar side ( Fig. 23 , f, g). They measure 0.80–1.00 mm and are spaced 0.45–0.80 mm apart. On the abpolypar side, these primary spines are smaller, conical and slightly inclined ( Fig. 23 , h, i). They measure 0.45–0.63 mm and are spaced 0.49–0.83 mm apart. On both sides the primary spines are papillose as well as tuberculated ( Fig. 23 , g–i), occasionally only on one side of the spine ( Fig. 23 , i). The secondary spines, interspersed between the primary spines, are small and very irregular in their shape and ornamentation ( Fig. 23 , j). They are either cylindrical, conical or triangular, smooth or with tubercles only at the tip or on their whole surface ( Fig. 23 , j).

Taxonomic remarks. Bo et al. (2012a) characterized the problematic genus Stichopathes for which they identified different phylogenetic clades. This species falls in “Clade D” of the groups described by these authors ( Bo et al. 2012a), where they tentatively identify the clade as Stichopathes cf. maldivensis . It also corresponds to the description of Stichopathes ? sp. made by Wagner (2015a) in Hawaii. The type specimen of this species is lost and was originally described from the Maldives at 67 m by Forster Cooper (1903). It was succinctly described as a straight colony (85 cm tall with a thick stem 4 mm in basal diameter) with two types of spines, where the primary ones were stout, conical and blunt with a papillose surface and knobs at the tip and the secondary spines were mostly triangular and irregularly distributed. No measures are given in the description, but an estimation from the drawing suggests that the height of primary spines in the type material (unknown region) is around 0.25 mm with an overall less crowded arrangement than in the present specimens and a lower density of tuberculation. However, this species, one of the most common in shallow-water Indo-Pacific assemblages (Clade D), presents a wide range of spine measures, shape and density of tuberculation depending on the considered region as well as the age of the colony ( Bo et al. 2012a). No other described straight Stichopathes species with thick stem matches the spine pattern of S. maldivensis . However, the synonymy of Cirrhipathes (?) flagellum Brook, 1889 with S. bispinosa is doubtful. Brook described a very long (3.5 m), thick straight and scarcely sinuous colony, with similarities in habit and size of this species with Cirrhipathes anguina , something also seen in SW Madagascar where they are usually found together at same depths and locations and with similar sizes. Brook’s specimen presents much elongated primary spines (0.5 mm tall) with small rounded prominences at their apex, and slender and elongate secondary spines. In addition, usually secondary spines are reported as triangular and small, while in Cirrhipathes (?) flagellum they are dinstinctly reported as slender and elongated, as it happens with the present Malagasy specimen and some Indonesian ones. Its attribution to the genus Cirrhipathes depends on poorly preserved polyps and therefore is questionable; consequently Cirrhipathes (?) flagellum might be related to the present one.

Distribution. Maldives (type locality, Cooper 1903), Indonesia ( Bo et al. 2012a), Hawaii ( Wagner 2015a), Madagascar (present study).

Figures

FIGURE 23. Stichopathes cf. maldivensis Forster Cooper, 1903. (a–c) In situ pictures showing the different morphologies that this species displays. A branched appearance is sometimes seen as a consequence of a breaking event, as shown by the white arrow. (d) White phenotype (INV.131372) with contracted polyps. (e) Brown-orange phenotype (INV.151020) with expanded polyps. The polyp row is twisting around the stem. (f) Section of a distal fragment measuring 4.5 mm in diameter (INV.131370). Polypar side is on the right. (g) Tall cylindrical polypar spines. (h) Conical abpolypar spines. (i) Close-up view of an abpolypar spine showing the tuberculation occurring on only one side. (j) Secondary spines.