Antipathes, Pallas, 1766Arachnopathes Milne Edwards, 1857,

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: 20-23

publication ID

https://doi.org/10.11646/zootaxa.4826.1.1

publication LSID

lsid:zoobank.org:pub:1DC59C31-61D1-4458-897B-29D9CA523634

DOI

http://doi.org/10.5281/zenodo.4448308

persistent identifier

http://treatment.plazi.org/id/F5768787-9371-427B-FF4C-F889FD77F8C1

treatment provided by

Plazi

scientific name

Antipathes Arachnopathes Milne Edwards, 1857
status

 

Antipathes  sp.

Fig. 12View FIGURE 12

Material examined. Soalara, 15 m. Entire colony, specimen INV.131338.

Depth range. 15–30 m.

Description. The living colony is bramble-like with the appearance of a mass of entangled and fused branches. It measures 25 cm in height and width in situ ( Fig. 12View FIGURE 12, a, b). The terminal branchlets are straight to slightly curved and their end is very thin. Branchlets are inserted almost perpendicular to the next lower order branch, but more often at 70–80°, even if more acute angles are also found ( Fig. 12View FIGURE 12, b). Branchlets are not regularly arranged nor in a single plane. They occur either uniserially or loosely biserially and are irregularly spaced 0.2–11 mm on the same side, with 3–5 branchlets per cm ( Fig. 12View FIGURE 12, b). Terminal branchlets measure up to 5 cm with basal diameter of around 0.6 mm, but more often less than 2.5 cm ( Fig. 12View FIGURE 12, b). Fusions are frequent between adjacent branches and branchlets. For instance, in a branch measuring 8 cm in length, 17 fusions are seen when considering all its branchlets (represented by the red dots in Fig. 12View FIGURE 12, b). The polyps are located in a single row that can twist around the thin branches but are irregularly spread out on thicker branches. Polyps measure 0.5–0.6 mm in diameter and are spaced 0.2–0.8 mm apart (mostly 0.4–0.5 mm). There are 10-11 polyps per cm.

The spines are widely varying in shape depending on the branch where they sit but are always smooth. On a branch measuring 0.16 mm in diameter, the spines are conical, measure 0.04–0.07 mm, and are spaced 0.13–0.26 mm apart ( Fig. 12View FIGURE 12, c). Most of them show two or more protuberances at the apex without distinction between polypar or abpolypar spines ( Fig. 12View FIGURE 12, c, g). For some spines the protuberances are found close to the base of the spine, consequently the conical shape is no more distinct ( Fig. 12View FIGURE 12, c). On such branches, four longitudinal rows are seen in one aspect ( Fig. 12View FIGURE 12, c). On a branch measuring 0.36 mm in diameter ( Fig. 12View FIGURE 12, d), the spines are either perpendicularly inserted or slightly inclined upward and 6–7 longitudinal rows are seen on lateral view. Most of them are conical ( Fig. 12View FIGURE 12, h), although spines with protuberances are occasionally found ( Fig. 12View FIGURE 12, d). Their size is the same as those of thinner branches, 0.04–0.07 mm, and they are spaced 0.22–0.36 mm apart. On larger branches measuring 0.5 mm ( Fig. 12View FIGURE 12, e), only four longitudinal rows of spines are seen, and all of the spines are almost conical. They are slightly inclined but not in the same direction ( Fig. 12View FIGURE 12, e, i). They measure 0.05–0.09 mm and are regularly spaced 0.19–0.37 mm apart, but often around 0.26 mm, giving the appearance of regular spacing. Finally, on branches measuring 0.80 mm in diameter the arrangement of the spines in longitudinal rows is no more visible ( Fig. 12View FIGURE 12, f). The spines can be conical but most of them are hooked and inclined in different directions ( Fig. 12View FIGURE 12, f, j). Their size remains constant as they measure 0.05–0.09 mm. Because they are not arranged in longitudinal rows, their mutual distance cannot be measured.

Taxonomic remarks. Currently, four valid species are known to be bramble-like: Antipathes chamaemorus Pax & Tischbierek, 1932  ; An. lenta Pourtalès, 1871  ; An. polyhedra Opresko, 2019  and An. rubusiformis Warner & Opresko, 2004  . Two other species, An. pauroclema Pax & Tischbierek, 1932  and An. simplex ( Schultze, 1896)  could possibly be similar, but both are only known from fragments. Antipathes simplex  is reported to have laterally compressed spines with rounded tips and inclined towards the end of the branch. They have a height of 0.085 mm on a branch 0.2 mm. Five to six longitudinal rows can be seen on one aspect, which becomes less distinct near the base of the corallum. Polyp transverse diameter has an average of 1 mm. Antipathes pauroclema  is reported to have variable spine morphologies. On what Pax & Tischbierek (1932) call the middle part of the skeletal axis, the spines are measuring 0.1 mm on average. On the tip of the branchlets, the spines reach 0.06 mm. In the largest part of the colony they are blunt cone-shaped, on the twig tips they are curved sharply and apically. They are arranged in five longitudinal rows and spaced 0.2–0.25 mm apart. The polyps measure 1.15 mm. Considering the wide variation of the spine morphology, size and arrangement depending on the thickness of the branch seen in the present specimen, as well as the small fragments from which An. simplex  and An. pauroclema  have been described, the two latter species cannot be compared confidently. For the remaining bramble-like species, only An. chamaemorus  and An. lenta  have triangular, smooth spines, while An. rubusiformis  has triangular and papillose spines and An. polyhedra  has tall and narrow spines ( Opresko 2019). Antipathes chamaemorus  differs from the present specimen by being a small colony not exceeding 3 cm in height, and in An. lenta  no mention is made about the presence of spines with protuberences as seen in the present specimen.

Distribution. Madagascar (present study).

Genus Arachnopathes Milne Edwards, 1857 

Arachnopathes  was established by Milne Edwards (1857) based on the type species Antipathes ericoides Pallas, 1766  . The genus was later questioned by Brook (1889) before being synonymized with Antipathes  by van Pesch (1914) and Pax & Muller (1955) ( Opresko 2006). In a more recent work, the species Arachnopathes columnaris Duchassaing, 1870  was chosen by Opresko (2006) as the type species of the genus Stylopathes  . The genus Arachnopathes  is characterized by branched and bushy colonies with short, straight or curved branchlets fused together into a thick mass ( Opresko 2006). The branchlets on the outer edges of the colony may be free or fused. The spines are smooth, triangular to conical to hooked upward, and can be forked.

There are currently five nominal species, of which two are known from the Indian Ocean: Arachnopathes ericoides ( Pallas, 1766)  which is the type species of the genus but for which the type material is lost, and Ar. clathrata ( Pallas, 1766)  for which there is no type. The remaining species, Ar. aculeata Brook, 1889  , Ar. indistincta ( van Pesch, 1914)  and Ar. sibogae ( van Pesch, 1914)  come from the Pacific Ocean. The latter two were originally assigned to the genus Aphanipathes  , but they are now provisionally referred to Arachnopathes  based on similarities in colony form and spine morphology (unpublished observations from co-author DMO). Further DNA analyses on Indian Ocean species might prove that they are related to the Stylopathidae  , but based on their spine morphology, they are inferred to be closer to Antipathidae  rather than Stylopathidae ( Opresko 2006)  .

Genus Arachnopathes Milne Edwards, 1857 

Arachnopathes  was established by Milne Edwards (1857) based on the type species Antipathes ericoides Pallas, 1766  . The genus was later questioned by Brook (1889) before being synonymized with Antipathes  by van Pesch (1914) and Pax & Muller (1955) ( Opresko 2006). In a more recent work, the species Arachnopathes columnaris Duchassaing, 1870  was chosen by Opresko (2006) as the type species of the genus Stylopathes  . The genus Arachnopathes  is characterized by branched and bushy colonies with short, straight or curved branchlets fused together into a thick mass ( Opresko 2006). The branchlets on the outer edges of the colony may be free or fused. The spines are smooth, triangular to conical to hooked upward, and can be forked.

There are currently five nominal species, of which two are known from the Indian Ocean: Arachnopathes ericoides ( Pallas, 1766)  which is the type species of the genus but for which the type material is lost, and Ar. clathrata ( Pallas, 1766)  for which there is no type. The remaining species, Ar. aculeata Brook, 1889  , Ar. indistincta ( van Pesch, 1914)  and Ar. sibogae ( van Pesch, 1914)  come from the Pacific Ocean. The latter two were originally assigned to the genus Aphanipathes  , but they are now provisionally referred to Arachnopathes  based on similarities in colony form and spine morphology (unpublished observations from co-author DMO). Further DNA analyses on Indian Ocean species might prove that they are related to the Stylopathidae  , but based on their spine morphology, they are inferred to be closer to Antipathidae  rather than Stylopathidae ( Opresko 2006)  .

Kingdom

Animalia

Phylum

Cnidaria

Class

Anthozoa

Order

Antipatharia

Family

Antipathidae

Kingdom

Animalia

Phylum

Cnidaria

Class

Anthozoa

Order

Antipatharia

Family

Antipathidae