Cirrhipathes cf. indica Summers, 1910

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 : 30-33

Cirrhipathes cf. indica Summers, 1910

Figs. 17 , 18

Cirrhipathes sp. Thomson & Simpson 1905, p.95, pl.1, fig.8

Cirrhipathes indica Summers 1910, p. 274 , pl.5, fig.9

Material examined. Two entire colonies, Toliara 45 m specimen INV.131341, and 52 m specimen INV.131348; one distal fragment of a third colony, Toliara 45 m specimen INV.131343 .

Depth range. 30–52 m.

Description. The colonies are unbranched and either straight, sinuous or sinuous with a single spiral ( Fig. 17 , a, Fig. 18 , a–c). Colonies without any spiral measure up to 100 cm in height ( Fig. 17 , a, Fig. 18 , a), while the one with the apical spiral measures 80 cm in height. The spiral is around 10 cm in diameter ( Fig. 18 , b, c). The coenenchyme is brown-greenish with white polyps, and cross groves are visible ( Fig. 17 , b, c, Fig. 18 , c). The polyps have thick, massive tentacles, which is especially true of the sagittal ones ( Fig. 17 , b, c), and around three polyps are found along one cm. When expended, the tentacles are long with rounded tips ( Fig. 18 , c). At the base of the stem, the polyps are irregularly spread around the axis ( Fig. 17 , b) but higher up they quickly tend to be gathered on one side without being crowded ( Fig. 17 , c, Fig. 18 , c). Polyps measure up to 3 mm in diameter and their mutual distance varies up to 4.5 mm.

The morphology and arrangement of the spines are dependent on their location along the corallum, and a variability is observed in their arrangement within and among specimens. Three main arrangements are seen from the apical portion to the basal one ( Fig. 17 , d–f, Fig. 18 , d–f). In the growing apical portion ( Fig. 17 , d, Fig. 18 , d), the spines are arranged in verticils, although not always distinctly layered. They are smooth, narrow, conical, slightly hooked with a pointed tip and inclined in different directions ( Fig. 17 , d, g). They have a few prominent tubercles at their top, not especially gathered on a single side of the spine ( Fig. 17 , g). In such section 0.63 mm in diameter, they measure 0.15–0.23 mm and are spaced 0.28-0.48 mm apart ( Fig. 17 , d). However, these spines arranged in verticils are not seen in every colony as illustrated in Fig. 18 , e, where the growing part is missing –apical breakages are common in whip corals– and thus the corallum ends with conical, tuberculated spines with a pointed tip and similar sizes as those from the middle parts ( Fig. 18 , e, g). On an apical part that is 3.1 mm in diameter, the central canal is 0.6 mm in diameter. In the middle portion of the stem (with varying diameters), the spines are either arranged in well defined longitudinal rows or with a slightly irregular arrangement ( Fig. 17 , e). In a section 3.3 mm in diameter, 11 longitudinal rows are seen. In these middle portions, the spine arrangement and morphology are identical in all specimens analyzed. The spines are conical, narrow to stout, with many tubercles all around their surface ( Fig. 17 , h, i), arranged in sort of verticils ( Fig. 17 , i) but this pattern is not regular on all spines. Adjacent spines can fuse together at their bases. There is no difference between polypar and abpolypar spines, both measure 0.19–0.24 mm on a section of corallum 3.3 mm in diameter, and they can reach 0.30 mm on a section 3.9 mm in diameter. They are spaced 0.29–0.62 mm apart. On the basal part just above the anchorage and measuring 6 mm in diameter, the spines are irregularly arranged ( Fig. 17 , f) and measure 0.14–0.18 mm. They are narrow, conical and have tubercles all around their surface, almost until their insertion ( Fig. 17 , j). On the basal part of the other specimen examined, and measuring 4.2 mm in diameter, the spines measure 0.11–0.21 mm ( Fig. 18 , e). Their arrangement does not appear so crowded as in Fig. 16 , f, leaving large areas devoid of spines ( Fig. 18 , f). No spiral arrangement is seen. Their morphology is similar to spines from the middle sections, but at the extreme base they are conical, with a pointed tip and only a few tubercles on a single side of the spine ( Fig. 18 , h). Fully tuberculated spines are observed only 1 mm above the basal anchorage ( Fig. 18 , i).

Taxonomic remarks. Tuberculated spines are found within both genera of whip black corals having more than one row of polyps, Pseudocirrhipathes and Cirrhipathes . To determine which genus the present specimens belong to, it is very important to analyze the polyps and the apical region of the stem. Pseudocirrhipathes polyps are typically not completely contractile, with long sagittal tentacles, and irregularly arranged along the stem leaving wide polyp-free areas. A peculiar large isorhiza is described for the cnidome of this genus. The colonies are characterized by a large hollow central canal and spines triangular or conical with many rounded tubercles at least in a portion of the stem ( Bo et al. 2009). In the apical portions of the stem, spines are arranged in verticils, a distinctive character. So far, only one species has been described for this genus, Pseudocirrhipathes mapia from the Indo-Pacific area ( Bo et al. 2009). This species is characterized by a typical tripartition of the spines’ arrangement along the stem, spiral a few cms above the basal plate, in regular longitudinal rows in the intermediate region and in clear verticils in the distal portion.

The present Malagasy specimens share all the generic features of Pseudocirrhipathes as well as some features of the type species including (i) similar sizes for the spines and polyps, (ii) regularly arranged longitudinal rows in the intermediate region, and (iii) a typical annular arrangement of tubercles on some spines. However, it differentiates from the type species by (i) not having spirally arranged spines at the base, as they are irregularly arranged, (ii) not presenting spines with a side free of tubercles, (iii) spines from the intermediate region can be stout and blunt rather than conical and narrow, (iv) verticils of spines are not distinctly spaced apart, and (iv) the morphology of the polyps is slightly different, with shorter tentacles.

Among similar Cirrhipathes species, only Ci. rumphii is known to have clearly tuberculated spines (even if only few at apex), but no other relatable taxonomic character. Cirrhipathes sp. sensu Thomson & Simpson, 1905, described from Sri Lanka (formerly known as Ceylon) at 84 m, was described has having distinctly papillose spines, but their size is only reported for the apical region as being 0.1 mm and their ornamentation is not clear in the drawings provided by these authors. The original description reports a 135 cm long (65 cm in height) whip colony coiled in three spirals of around 10 cm and hollow; no information was given on polyps. It was clearly mentioned that this specimen has spines arranged in distinct verticils at the apex, while they are irregularly arranged in the intermediate and the basal regions of the stem. This latter species has been included in the past in Cirrhipathes indica Summers, 1910 from Mozambique ( Portuguese East Africa) by Summers (1910), before being considered closer to Pseudocirrhipathes by Bo et al. (2009). In the poorly described species Ci. indica , whose type is lost, the colony, showing a hollow canal, is reported to be wound in a large circle of 18 cm in diameter with polyps, badly preserved, distributed all around but gathered together in some parts. The spines are described as being minute and papillose, all alike and equal, irregularly arranged ( Summers 1910). It was related to Cirrhipathes sp. sensu Thomson & Simpson, 1905 by Summers (1910) but neither the description nor the drawing mentioned verticils. Bo et al. (2009) already highlighted that the association of Cirrhipathes sp. Thomson & Simpson with Pseudocirrhipathes mapia was not certain mainly due to the absence of a basal spiral arrangement of the spines, a feature shared with Ci. indica . The occurrence of verticils and a distinctly hollow canal, however, were considered features relatable at least at a generic level with Pseudocirrhipathes .

Considering all this information, the species described here shares significant features with those by Thomson & Simpson (1905) and, possibly, Summers (1910). It is plausible that a new Pseudocirrhipathes species, based on Ci. indica and including Cirrhipathes sp., should be re-described here.

Distribution. Mozambique (type locality, Summers 1910), Sri Lanka ( Thomson & Simpson 1905), Madagascar (present study).

Figures

FIGURE 16. (a, c) Cirrhipathes densiflora Silberfeld, 1909 type specimen (schizotype USNM 100475) from Japan. (b, d) Cirrhipathes contorta van Pesch, 1910 type specimen (schizotype USNM 100414) from Indonesia.

FIGURE 17. Cirrhipathes cf. indica Summers, 1910 specimen INV.131341. (a) In situ picture of the entire colony. (b) Closeup view of the polyp arrangement on the basal part. (c) In situ close-up view of the polyp arrangement in the intermediate region showing a side free of polyps. (d) Section of the growing apical region 0.63 mm in diameter and showing irregularly verticillated spines. (e) Section of the intermediate region 3.6 mm in diameter. (f) Section of the basal region just above the basal anchorage measuring 6 mm in diameter. (g) Spines of the apical part. (h–i) Spines of the intermediate region. (j) Spine of the basal region.

FIGURE 18. Cirrhipathes cf. indica Summers, 1910 (a–b) Morphological variations of the species (a—INV.131348, b— INV.131343). (c) Close-up view of the coil in the apical part of the colony INV.131343, with expanded polyps. (d) Detailed view of a growing apical part in INV.131348 where the verticillated spines are found in the bright, narrow part. (e) Detailed view of an apical part lacking the growing skeleton in INV.131343. (f) Section of a basal part in INV.131343 just above the anchorage and measuring 4.2 mm in diameter. (g) Spines of the apical part shown in e). (h) Spine found just above the basal anchorage and showing a few tubercles at the top. (i) Succession of spines near the basal anchorage, where a fully tuberculated one is seen at the top, only 1 mm above the base of the stem.