Whip black corals (Antipatharia: Antipathidae: Stichopathes) of the Mesophotic Coral Ecosystem of Mo’orea (French Polynesia), with the description of a new species Author Terrana, L. Natural History Museum and Vivarium of Tournai, Cour d’Honneur de l’Hôtel de ville 52, 7500 Tournai, Belgium Author Rouzé, H. University of Guam, Marine Laboratory, Mangilao 96923, Guam Author Opresko, D. M. Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, 10 th and Constitution Ave, NW, Washington, DC 20560 USA Author Consortium, Under The Pole Under The Pole, 1 rue des Senneurs, 29900 Concarneau, France Author Eeckhaut, I. Biology of Marine Organisms and Biomimetics, University of Mons, Av. Champ de Mars 6, 7000 Mons, Belgium Author Dubois, P. Marine Biology Laboratory, Université Libre de Bruxelles, Av. F. D. Roosevelt 50, CP 160 / 15, 1000 Bruxelles, Belgium Author Hédouin, L. Under The Pole, 1 rue des Senneurs, 29900 Concarneau, France & PSL Research University, EPHE-CNRS-UPVD, USR 3278 CRIOBE, BP 1013, 98729 Papetoai, Mo’orea, French Polynesia; Laboratoire d’Excellence « CORAIL », Mo’orea, French Polynesia Author Godefroid, M. Marine Biology Laboratory, Université Libre de Bruxelles, Av. F. D. Roosevelt 50, CP 160 / 15, 1000 Bruxelles, Belgium text Zootaxa 2024 2024-07-25 5486 2 182 212 http://dx.doi.org/10.11646/zootaxa.5486.2.2 journal article 10.11646/zootaxa.5486.2.2 1175-5326 13209941 2CBD1AF5-1B48-4DD1-B3C7-E3BEAB4E7559 Stichopathes cf. contorta Thomson & Simpson, 1905 Stichopathes contorta Thomson & Simpson, 1905 , p. 100 , plate 3 ( Figs. 7–9 ) Material examined. Entire colonies collected between 70 and 100 m depth. Specimens NHMT-R2E1005 ; NHMT-R2E1004 ; NHMT-R2E1006 . Type locality. “ From off Galle and onwards up West Coast of Ceylon ” ( Thomson & Simpson, 1905 ). Description of Mo’orea specimens. Specimen NHMT-R2E1005 has a thin skeleton, 1 mm in basal diameter, 0.52 mm at the apex. Corallum is contorted in a well-defined pattern, not forming any defined loop nor coil ( Fig. 7 , a–b). It is 84 cm in length, 34 cm in height ( Fig. 7 , a–b). The polyps in a single row, 7–9 per centimeter, they twist around the corallum. They measure 0.91–1.18 mm in transverse diameter and are spaced 0.37–0.80 mm apart. FIGURE 7. Stichopathes cf. contorta . General views of entire colonies, which always have a well-defined contorted pattern. ( a–b ) In situ and laboratory illustrations of specimen NHMT-R2E1005. ( c ) Specimen NHMT-R2E1004. ( d ) Specimen NHMT-R2E1006. The spines along the corallum vary from triangular to conical, either with an acute or a bifid/notched tip, more often blunt on middle parts. There are 7–8 longitudinal rows seen from one aspect. In basal and apical parts the arrangement tends to be irregular ( Figs. 8 , 9 ). Density of spines is 2/mm (apical), 3/mm (middle) and 3–6/mm (basal). There are no secondary spines on any section ( Fig. 8 ). On basal sections, spines are small, triangular to conicalThey have an acute or bifid tip, with rounded papillae and/or papillae elongated towards the tip of the spine, generally on the upper half of their surface. They measure 0.07–0.14 mm and are spaced 0.27–0.64 mm apart. A polypar side cannot be clearly defined, as the coenenchyma on the basal section often lacks polyps. In the middle section, Polypar spines measure 0.08–0.14 mm and are spaced 0.45–0.66 mm apart ( Fig. 9 , b, e). They are conical, and mostly simple, sometimes bifid (or notched), with rounded papillae on the whole surfacesometimes elongated to the point that they almost form ridges ( Fig. 9 , b, e). Abpolypar spines are smaller and more triangular, almost always with a simple tip, with the same ornamentation as the polypar spines ( Fig. 9 , h). They measure 0.06–0.09 mm and are spaced 0.36–0.61 mm apart ( Fig. 9 , h). On the growing portions of the apical parts, the spines tend to be laterally compressed ( Fig.10 , c, f, i). The polypar apical spines are conical either simple or bifid, with narrow elongated papillae on two thirds or the entire surface of the spine ( Fig. 8 , c). They measure up to 0.14 mm , while abpolypar spines measure up to 0.09 mm . The latter are triangular and tend to have less papillae on their surface ( Fig. 9 , i). Other specimens referred to S. cf. contorta : Specimen NHMT-R2E1004 thin, regularly contorted ( Fig. 7 ). Basal, middle and apical diameters are 0.93 mm , 0.79 mm , and 0.26 mm , respectively. Colony length 44 cm , height 8 cm . Polyps 0.91–0.96 mm in diameter, spaced 0.3–0.5 mm apart, with 6–8 polyps/cm. Specimen NHMT-R2E1006 thin, regularly contorted ( Fig. 7 ). Basal, middle and apical diameters are 0.76 mm , 0.68 mm , and 0.27 mm , respectively. Colony length 60 cm , height 18 cm . Polyps measure 0.91–1.18 mm spaced 0.25–0.60 mm apart. There are 6–8 polyps/cm. Both specimens have the same spine shape and ornamentation than NHMT-R2E1005 and sizes falls within the same range as previously described. They have 3–4 spines/mm in the apical section, 2–3 spines/mm in the middle section, and 2–4 spines in the basal section. FIGURE 8. Basal, middle, and apical sections of the skeletons of Stichopathes cf. contorta , with the polypar sides oriented on the right on the middle sections. ( a–c ) NHMT-R2E1005.S1–S3 sections 1 mm, 0.74 mm and 0.52 mm in diameter respectively. ( d–f ) NHMT-R2E1004.S1–S3 sections 0.83 mm, 0.81 mm and 0.37 mm in diameter respectively. Taxonomic discussion. Based on ITS1 molecular data, this species groups within Clade B as described by Bo et al. (2012) . Clade B of Bo et al. (2012) was originally characterized by colonies having thick stems (more than 1 mm in the apical portion), triangular-conical spines with small papillae or tubercles, and in some cases by small secondary spines. Spines on some colonies may have apical tubercles, which at times may be completely lacking. The Indonesian specimens BUK11 and INDO19, which grouped with the Polynesian specimen S. cf. contorta , are described as having a thick corallum with convolutions mostly flat and meandritic, the absence of a significant number of secondary spines, and large polypar spines (up to 0.42 mm high) with only a few apical tubercles and basal papillae (apical tubercles are seen in Fig. 3 , k–p in Bo et al. 2012 ). The polyps in Indonesian specimens measure 1.0– 1.4 mm and 6–7 are found per cm. This difference may be due to the presence of young, small polyps in some parts of the colony, increasing the polyp density. The Polynesian specimens share the spine shape and ornamentation with the Indonesian specimens, and the inclusion of the Mo’orea specimens within Clade B extends its general morphological characteristics. Spines are different from those of S. desaturata sp. nov. by sometimes being notched at the tip or by having multiple apical lobes. In the nominal species described to date, only a limited number are characterized by a thin, sinuous/contorted corallum, with conical, papillose spines having simple or multiple tips. One is the species S. pourtalesi , recently redescribed, which has spines different in their ornamentation and shape from the present specimens ( Bo & Opresko 2015 ). The species Stichopathes semiglabra van Pesch, 1914 , ( 55–94 m in Indonesia ), is reported as having a very thin skeleton, only 0.1 mm at the base, then up to 0.54 mm upwards and forming three coils. The shape of the corallum is not comparable to the present specimens. The sizes and mutual distance of spines reported for the present specimens fall in the range of S. semiglabra , but in the latter they are described as blunt, conical, slightly inclined, smooth or papillose: here, they are never found smooth. The interpolypar distance reported by van Pesch is 1.7–1.8 mm , but he measured it from the base of the sagittal tentacles of one polyp to the base of the sagittal tentacles of the adjacent polyp, which is not truly an interpolypar distance (generally measured from the distal edge of the distal lateral tentacle of one polyp to the proximal edge of the proximal lateral tentacle of the adjacent polyp). Based on his Figure 193 ( van Pesch, 1914 ), the transverse diameter is about 1.07 mm , and the interpolypar space is about 1.4 mm , but this is for preserved material where the polyps are likely to be very contracted, thus making the interpolypar space larger. An example of polyp shape and size variation is given in Fig. 10 , where the same polyps are shown in situ , freshly sampled, and after a few months of storage in 70% ethanol, drawing attention to the effects of storage on polyp morphometrics. FIGURE 9. Stichopathes cf. contorta NHMT-R2E1005.S1–S3. ( a, d, g ) Basal spines that cannot be characterized as polypar/ abpolypar due to the lack of polyps in this zone. ( b, e ) Polypar spines of the middle section. ( c ) Spine of the apical section. ( f, i ) Abpolypar spines of the apical section. ( h ) Spine of the middle section. The species Stichopathes variabilis var. asperina has specimens morphologically similar to Mo’orea specimens of S. cf. contorta (see Table 2 for morphological details). The presence of “abnormal types of spines” referring to double spines growing behind each other in the same longitudinal row is reported, as well as young spines on the top of the colonies which “are furnished with two or three tops [...] usually smooth” ( van Pesch 1914 , Figs. 126–128). The drawings of van Pesch do not represent notched spines as seen here in S. cf. contorta nor are they reported as frequently occurring in middle sections of the corallum, as it is the case here in the Mo’orea specimens. Pending an extensive revision of S. variabilis , a confident comparison cannot be made. The only molecular data available to date for specimens presumably identified as S. variabilis by Miller et al. (2010) do not confirm a close relationship to the specimens here referred to S. cf. contorta . Lastly, S. contorta Thomson & Simpson, 1905 , is the species that is the closest to the Mo’orea specimens. It has been described from Ceylon as having a “very sinuous” corallum not exceeding 1 mm in diameter (as seen in the Mo’orea specimens), with the spines reported to be “slightly but distinctly papillose […] nearest S. lutkeni (BROOK) ”. Spines of S. luetkeni shown in Opresko & Sanchez (2005) are stout, blunt and papillose, and longer on polypar sides, which are different from those of the present specimen. Thomson & Simpson (1905) did not mention the presence of notched/multi-lobed spines nor their size. However, a reexamination of the type of S. contorta located in the Natural History Museum (London) (BM 1908.2.18.8) has shown that some of the spines presented notches at their tip and were slightly papillose, almost not distinct. Older descriptions might have reported that the spines were smooth and/or without any notches nor apical lobes, but sometimes very small papillae and even apical lobes might have been overlooked because the authors did not use adequate magnification or did not look along enough parts of the axis. The polyps of the type of S. contorta measure 1 mm in transverse diameter, with 5–6 per cm (here polyps 0.9–1.2 mm in diameter, 6–9 per centimeter). Due to these similarities, the name Stichopathes cf. contorta is assigned to the present specimens.