Chrysogorgia pendula Versluys, 1902

Xu, Yu, Zhan, Zifeng & Xu, Kuidong, 2023, Studies on western Pacific gorgonians (Anthozoa: Octocorallia, Chrysogorgiidae). Part 1: a review of the genus Chrysogorgia, with description of a new genus and three new species, Zootaxa 5321 (1), pp. 1-107 : 83-87

Chrysogorgia pendula Versluys, 1902

Figs. 52–71 ; Tables 8 , 9

Chrysogorgia pendula Versluys, 1902: 73–74 , figs. 113–118.

Chrysogorgia pendula: Kükenthal, 1919: 526 .

Chrysogorgia pendula: Pasternak, 1981: 50 .

Material examined. MBM286359 , station FX-Dive 172 (17°23′21″N, 153°5′32″E), Kocebu Guyot in Magellan Seamounts , 1353 m, 1 April 2018 . MBM286360 , station FX-Dive 132 (10°23′21″N, 140°9′28″E), a seamount (tentatively named as M4) on the Caroline Ridge , 1417 m, 14 August 2017 . MBM286863 , station FX-Dive 211 (10°2′59″N, 140°10′30″E), a seamount (tentatively named as M5) on the Caroline Ridge , 1473 m, 29 May 2019 ; MBM286864 , station FX-Dive 221 (10°3′05″N, 140°9′24″E), M5 seamount, 2036 m, 9 June 2019 . MBM286865 , station FX-Dive 210 (10°4′44″N, 140°9′24″E), M5 seamount, 1895 m, 10 June 2019 . MBM286866 , station FXDive 224 (10°37′33″N, 140°5′22″E), a seamount (tentatively named as M8) on the Caroline Ridge , 1412 m, 12 June 2019 ; MBM286867 , station FX-Dive 227 (10°37′54″N, 140°5′37″E), M8 seamount, depth 1695 m, 15 June 2019 . MBM286868 , station FX-Dive 226 (10°38′11″N, 140°4′5″E), M8 seamount, 1832 m, 14 June 2019 . MBM286869 , station FX-Dive 227 (10°37′56″N, 140°5′37″E), M8 seamount, 1711 m, 15 June 2019 . MBM286870 , station FXDive 221 (10°3′6″N, 140°9′30″E), M5 seamount, 1668m, 9 June 2019 .

Description. Colony typical bottlebrush-shaped and attached to rocky substrate. Branching sequencing 2/ 5L. Branches arranged closely at the stem base and became loose on the top. Branches usually slightly bend down and form an acute angle with the stem, and subdivided dichotomously. Distance between adjacent branch up to 15 mm, the first internode of branch up to 12 mm long and terminal branchlets up to 16 mm long. Nonterminal polyps usually with an oval body and became narrow at tentacle base, some of them pitcher-like, 1–2 mm tall. Terminal polyps usually cylindrical or conical with its base narrow, up to 3.5 mm tall. Polyps arranged one or two on first and medial internode, and up to four in terminal branchlets. Polyps in stem internodes very small and usually with opening mouth and eight tentacles. Eggs often observed in the oval body of polyps (e.g., Fig. 52C, E ). Some polyps and branches occasionally covered with flexible filaments, which could not be digested by sodium hypochlorite, and usually form a slender and sharp point above the head of polyps ( Fig. 66C, F–I ).

Scales in aboral face of tentacle rachis transversely arranged in a single row and a little curved with sparse fine warts, usually branched or forked with irregular shape, some of them nearly smooth and one end become narrow and sharp. Scales in pinnules longitudinally arranged, slender and a little curved, nearly smooth or with sparse fine warts, some of them with one end broad or forked and the other end narrow or sharp. Scales in polyp body wall obliquely or transversely arranged, elongate and nearly smooth with an obvious medial contraction, some of them lobed or forked with irregular shape, occasionally with finely toothed edges and protruding ridges on surface. Some small irregular scales often present and scattered on the outermost layer of the large scales on basal polyp body wall ( Fig. 68H ). Scales in coenenchyme arranged along to the branch, small and smooth, usually biscuit-like or elongate with a slight medial contraction, some of them crosswise and lobed with irregular shape. Plates or scales in the polyp mouth area near the tentacles sometimes present, small and thick, usually a little curved and coarse with many warts and irregular shape.

For the morphological measurements of the ten specimens, see Table 8 .

Distribution and habitat. Banda Sea, 1595 m ( Versluys 1902); Marcus-Necker Ridge, 2060–2100 m ( Pasternak 1981); seamounts on the Caroline Ridge, 1412–2036 m; Kocebu Guyot in Magellan Seamounts, 1353 m.

Remarks. Chrysogorgia pendula Versluys, 1902 is characterized by a typical bottlebrush-shaped colony, 2/5L branching sequence, pendulous branches, smooth biscuit-like scales in coenenchyme, irregular scales with a medial contraction in polyp body wall, irregular scales with sparse fine warts in tentacles and smooth scales usually with one end broad or forked and the other end narrow in pinnules. Our ten specimens match well with the original description of C. pendula in sclerite forms and pendulous branches, and their 28S rDNA sequences showed they are identical with the intraspecific differences (see the genetic analysis before), we thus identified as the same species.

However, there are minor differences among the ten specimens including: (1) the colony is slender bottlebrush-shaped with a little curved stem in MBM286865 , typical and regular bottlebrush-shaped in MBM286360 , MBM286359 , MBM286863 , MBM286864 , MBM286869 and MBM286870 , bottlebrush-shaped with two large branches in MBM286866 , relatively bushy and stout bottlebrush-shaped in MBM286867 and MBM286868 ; (2) scales in coenenchyme are more elongate in MBM286864 and MBM286867 , more irregular in MBM286870 ; (3) scales in pinnules are more forked and irregular in MBM286864 , MBM286867 and MBM286870 ; (4) small and thin sclerites with many warts are more abundant in MBM286869 ; (5) some polyps of MBM286869 covered with flexible filaments ( Fig. 66C, F–I ). All of these differences may be caused by different growth stage/environment and inadequate measurement, and are not constant features, and we tend to treat as the conspecific variation. The ten specimens of Chrysogorgia pendula Versluys, 1902 indicate this species have high intraspecific variations.

Figures

FIGURE 52. The external morphology and polyps of Chrysogorgia pendula Versluys, 1902, specimen MBM286360. A, B. The same specimen in situ and after collection. C. Two non-terminal polyps filled with eggs under a light microscope. D, F. Single terminal polyps under a light microscope and SEM, respectively. E. A single non-terminal polyp filled with eggs under SEM. G. A part of branch under SEM. Scale bars: 5 cm (B); 1 mm (C–F); 300 μm (G).

FIGURE 53. Sclerites of Chrysogorgia pendula Versluys, 1902, specimen MBM286360. A. Sclerites in tentacle rachis. B. Sclerites in polyp body wall. C. Sclerites in coenenchyme. D. Sclerites in pinnules. E. Some warty scales in tentacles. Scale bars: 300 μm (A–C in the same scale); 100 μm (D, E).

FIGURE 54. The external morphology and polyps of Chrysogorgia pendula Versluys, 1902, specimen MBM286863. A, B. The same specimen in situ (the arrow) and after collection. C, E. Single non-terminal polyps under a light microscope and SEM, respectively. D. A single terminal polyp under a light microscope. F. A part of branch under SEM. Scale bars: 5 cm (B); 1 mm (C–E); 300 μm (F).

FIGURE 55. Sclerites of Chrysogorgia pendula Versluys, 1902, specimen MBM286863. A. Sclerites in tentacle rachis. B. Sclerites in polyp body wall. C Sclerites in coenenchyme. D Some warty sclerites in polyp mouth area near the tentacles. E Sclerites in pinnules. Scale bars: 300 μm (A–C and D–E in the same scale, respectively).

FIGURE 56. The external morphology and polyps of Chrysogorgia pendula Versluys, 1902, specimen MBM286864. A, B. The same specimen in situ and after collection. C, E, F. Single non-terminal polyps under a light microscope and SEM, respectively. D. Single terminal polyps under SEM. G. A part of branch under SEM. Scale bars: 5 cm (B); 1 mm (C–F); 300 μm (G).

FIGURE 57. Sclerites of Chrysogorgia pendula Versluys, 1902, specimen MBM286864. A. Sclerites in tentacle rachis. B. Sclerites in polyp body wall. C. Sclerites in coenenchyme. D. Some warty sclerites in polyp mouth area near the tentacles. E. Sclerites in pinnules. Scale bars: 300 μm (A, B and E in the same scale); 200 μm (C and D in the same scale).

FIGURE 58. The external morphology and polyps of Chrysogorgia pendula Versluys, 1902, specimen MBM286866. A, B. The same specimen in situ and after collection. C. A single non-terminal polyps under a light microscope. D, E. Single terminal polyps under a light microscope and SEM, respectively. F. Basal polyp body wall under SEM. G. A part of branch under SEM. Scale bars: 10 cm (B); 1 mm (C–E); 300 μm (F, G).

FIGURE 59. Sclerites of Chrysogorgia pendula Versluys, 1902, specimen MBM286866. A. Sclerites in tentacle rachis. B. Sclerites in polyp body wall. C. Sclerites in coenenchyme. D. Some warty sclerites in polyp mouth area near the tentacles. E. Sclerites in pinnules. Scale bars: 300 μm (A–C in the same scale); 200 μm (D and E in the same scale).

FIGURE 60. The external morphology and polyps of Chrysogorgia pendula Versluys, 1902, specimen MBM286359. A, C. The same specimen in situ and after collection. B, D, G. Single non-terminal polyps under a light microscope and SEM, respectively. E, F. Single terminal polyp under a light microscope and SEM, respectively. H. A part of branch under SEM. I. Basal polyp body wall under SEM. J. Tentacular part under SEM. Scale bars: 10 cm (C); 1 mm (B, D–G); 500 μm (H–J).

FIGURE 61. Sclerites of Chrysogorgia pendula Versluys, 1902, specimen MBM286359. A. Sclerites in tentacle rachis. B. Sclerites in polyp body wall. C. Some warty sclerites in tentacles. D. Sclerites in pinnules. E. Some warty and thick sclerites in polyp mouth area near the tentacles. F. Sclerites in coenenchyme. Scale bars: 300 μm (A, B, F in the same scale); 200 μm (D, E in the same scale); 100 μm (C).

FIGURE 62. The external morphology and polyps of Chrysogorgia pendula Versluys, 1902, specimen MBM286867. A, B. The same specimen in situ and after collection. C. A terminal branchlet under a light microscope. D. A part of branch under SEM. E, G. Single terminal polyps under a light microscope and SEM, respectively. F. A single non-terminal polyp under a light microscope. Scale bars: 10 cm (B); 5 mm (C); 1 mm (E–G); 200 μm (D).

FIGURE 63. The sclerites of Chrysogorgia pendula Versluys, 1902, specimen MBM286867. A. Sclerites in tentacle rachis. B. Sclerites in polyp body wall. C. Sclerites in pinnules. D. Some warty sclerites in polyp mouth area near the tentacles. E. Sclerites in coenenchyme. Scale bars: 300 μm (A–C and E in the same scale); 100 μm (D).

FIGURE 64. The external morphology and polyps of Chrysogorgia pendula Versluys, 1902, specimen MBM286868. A, C. The same specimen in situ and after collection. B, D. Single non-terminal polyps under a light microscope. E, F. Single terminal polyps under a light microscope and SEM, respectively. G. Two parts of branch under SEM. Scale bars: 5 cm (C); 1 mm (B, D–F); 500 μm (G).

FIGURE 65. The sclerites of Chrysogorgia pendula Versluys, 1902, specimen MBM286868. A. Sclerites in tentacle rachis. B. Sclerites in pinnules. C. Sclerites in polyp body wall. D. Sclerites in coenenchyme. E. Some warty sclerites in polyp mouth area near the tentacles. Scale bars: 200 μm (A, C, D in the same scale); 100 μm (B, E in the same scale).

FIGURE 66. The external morphology and polyps of Chrysogorgia pendula Versluys, 1902, specimen MBM286869. A, B. The same specimen in situ and after collection. C, F, G. Single non-terminal polyps under a light microscope and SEM, respectively. D, E, H. Single terminal polyps under a light microscope and SEM, respectively. I. Polyp body wall covered with flexible filaments. Scale bars: 5 cm (B); 1 mm (C–H), 500 μm (I).

FIGURE 67. Sclerites of Chrysogorgia pendula Versluys, 1902, specimen MBM286869. A. Sclerites in tentacle rachis. B. Sclerites in polyp body wall. C. Sclerites in coenenchyme. D. Large warty sclerites in the polyp mouth area near the tentacles. E. Sclerites in pinnules. F. Small warty sclerites in tentacles. Scale bars: 200 μm (A–C in the same scale); 100 μm (D–F; E and F in the same scale).

FIGURE 68. The external morphology and polyps of Chrysogorgia pendula Versluys, 1902, specimen MBM286865. A, C. The same specimen in situ and after collection. B. Single non-terminal polyps under a light microscope. D. Small polyps on the stem under a light microscope. E, F. Single terminal polyps under a light microscope and SEM, respectively. G. A part of branch under SEM. H. Basal polyp body wall under SEM. Scale bars: 5 cm (C); 1 mm (B, D–F); 200 μm (G, H).

FIGURE 69. Sclerites of Chrysogorgia pendula Versluys, 1902, specimen MBM286865. A. Sclerites in tentacle rachis. B. Sclerites in polyp body wall. C. Sclerites in pinnules. D. Sclerites in coenenchyme. E. Some warty sclerites in polyp mouth area near the tentacles. Scale bars: 300 μm (A–D in the same scale); 100 μm (E).

FIGURE 70. The external morphology and polyps of Chrysogorgia pendula Versluys, 1902, specimen MBM286870. A, B. The same specimen in situ and after collection. C, F. Single non-terminal polyps under a light microscope and SEM, respectively. D, E. Single terminal polyps under a light microscope and SEM, respectively. G. The inner side of tentacle under SEM. Scale bars: 5 cm (B); 1 mm (C–F); 200 μm (G).

FIGURE 71. Sclerites of Chrysogorgia pendula Versluys, 1902, specimen MBM286870. A. Sclerites in tentacle rachis. B. Sclerites in pinnules. C. Sclerites in polyp body wall. D. Sclerites in coenenchyme. E. Some thick and warty sclerites in tentacles. Scale bars: 200 μm (A–D in the same scale), 50 μm (E).