Chironephthya sirindhornae, Imahara & Chavanich & Viyakarn & Kushida & Reimer & Fujita, 2020

Imahara, Yukimitsu, Chavanich, Suchana, Viyakarn, Voranop, Kushida, Yuka, Reimer, James D. & Fujita, Toshihiko, 2020, Two new species of the genus Chironephthya (Octocorallia, Alcyonacea, Nidaliidae Siphonogorgiinae) from the Gulf of Thailand, Zootaxa 4780 (2), pp. 324-340 : 328-332

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Chironephthya sirindhornae

sp. nov.

Chironephthya sirindhornae sp. nov.

( Figs. 2–7 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 )

Japanese name: Hime-kudayagi

Holotype. NSMT-Co 1703, at 19 m depth, Hin Lom Fang , off Pattaya, Chonburi Province, Thailand (12°48.37'N, 100°42.35'E), on 13 October 2013. GenBank Accession No. MT 424941 View Materials (mtMutS), MT 414716 View Materials (COI), MT 419962 View Materials (28SrDNA). GoogleMaps

Description. Colony form: Colony, 34 mm high, consisting of nine polyparia arising from a thin membranous common base, spreading over the dead holaxonian axis of 55 mm long and 3–13 mm wide, soft and somewhat translucent in life ( Fig. 2 View FIGURE 2 ) but stiff and opaque in ethanol ( Fig. 3 View FIGURE 3 ). Inside the common base, there are several canals, 0.2–0.6 mm in diameter, penetrated. Lower portion of each polyparium is a short sterile stem, 3–14 mm long and 2.0 x 2.5–5.2 x 6.5 mm in diameter in the proximal portion. Polyparia 7–47 mm high (including lower stem), sparsely branched in one plane. Terminal branches short, rod-like when alive, but deformed into club-shape with distal swollen portion with slightly withered polyparia after fixation, 2–4.6 mm long and 1.5 x 2.0– 4.8 x 5.2 mm in diameter at the most swollen portion. The interior of stem, there are four to six thick canals leading to apical polyps and other two to three thin canals. Canal walls are thin, soft and limp.

Polyps: Polyps monomorphic, distributed at long intervals on the upper stem ( Fig. 4B View FIGURE 4 ), arranged sparsely, somewhat in a spiral formation on the lateral sides of branches ( Fig. 4A View FIGURE 4 ), and crowded 4–6 in number at the distal portion of each terminal branch ( Fig. 4D, E View FIGURE 4 ). Calyces, in two types, cup-shaped ( Fig. 4E View FIGURE 4 ) at distal portion of terminal branches, and shelf-like ( Fig. 4A View FIGURE 4 , 5A, B View FIGURE 5 ) on lateral sides of branches and stem. Both types of calyces supported by 2–3 teeth formed by 5–7 large spindles of <2 mm long ( Fig. 7A View FIGURE 7 1 View FIGURE 1 ) on the outer surface, and having small slender spindles or needles of <0.2 mm long ( Fig. 7A View FIGURE 7 2 View FIGURE 2 ) embedded in the inner surface. Anthocodiae ( Fig. 5 View FIGURE 5 C–D), <0.8 mm high and <1 mm wide, armed by eight points and a crown. Each point consists of one pair of large spindles of <0.46 mm and 2–3 pairs of small spindles of <0.23 mm long ( Fig. 6B View FIGURE 6 ). Crown bearing 6–8 rows of horizontally-disposed curved spindles <0.43 mm long ( Fig. 6D View FIGURE 6 ). Between two adjacent points, intermediate sclerites of 1–2 pairs of rods, <0.18 mm long ( Fig. 6C View FIGURE 6 ). Anthocodial formula: 1P+(2–3)p+(6–8)Cr+(1–2)M. The axis of each tentacle has many small rods, reaching 0.11 mm in length, ( Fig. 6A View FIGURE 6 ) arranged perpendicular to the axis or in a chevron toward the distal end. Pinnules completely free from sclerites. Pharynx has several small spiny spindles reaching 0.05 mm in length ( Fig. 6E View FIGURE 6 ).

Sclerites of coenenchyme: Surface layer of branches covered tightly with vertically aligned large spindles of <2.68 mm long with many complex warts ( Fig. 7B View FIGURE 7 1 View FIGURE 1 ), and slender spindles of <0.74 mm long with a few complex warts and blunt ends ( Fig. 7B View FIGURE 7 2 View FIGURE 2 above), and small curved spindles of <0.18 mm long with a few conical warts ( Fig. 7B View FIGURE 7 2 View FIGURE 2 below). Interior of branches containing a few needles of <0.24 mm long with a few large simple warts ( Fig. 7C View FIGURE 7 ). Surface layer of stem and common base covered tightly with large spindles of <2.78 mm long with many complex warts ( Fig. 7D View FIGURE 7 1 View FIGURE 1 ) and slender spindles of <0.66 mm long with a few complex warts ( Fig. 7D View FIGURE 7 2 View FIGURE 2 ). Interior of stem and common base containing a few spindles of <0.49 mm long with a few compound warts ( Fig. 7E View FIGURE 7 1 View FIGURE 1 ), and a few needles of <0.28 mm long with a few conical warts ( Fig. 7E View FIGURE 7 2 View FIGURE 2 ).

Color: Colony translucent pale pink, with yellow point sclerites and red crown sclerites in life. The color of colony changes to opaque dull pale pink in ethanol.

Etymology. The specific epithet is named in honor of Her Royal Highness Princess Maha Chakri Sirindhorn of Thailand, who has initiated and implemented the Plant Genetic Conservation Project for maintenance and conservation of biodiversity both on land and in the ocean.

Remarks. This new species differs from other species of Chironephthya in that it has multiple stems arising from a common base, and lacks large spindles in the interior of the coenenchyme. This species is distinguished clearly from its congener C. macrospiculata Thomson & Henderson, 1906 by the size of coenenchyme cortical spindles (<8.3 mm long) and by the structure of anthocodial formula (2P+2p+3Cr).

The appearance of the living colony of this species is very similar to that of Scleronephthya , but the presence of the calyx existing at the proximal portion of polyps and vertically-aligned spindles on the cortex of the coenenchyme enables distinguishing between them underwater, if carefully observed.


Mus. Tinro, Vladyvostok