Corallium gotoense, Nonaka & Muzik & Iwasaki, 2012

Nonaka, Masanori, Muzik, Katherine & Iwasaki, Nozomu, 2012, 3428, Zootaxa 3428, pp. 1-67 : 26-36

Corallium gotoense sp. nov. ( Figs. 18–24; Tables 2, 5)

Material examined: Holotype, USNM 19928 , Goto , Kyushu , Japan. The specimen is dry and was donated by Kishinouye and labeled by him as “ C. elatius , white color-variation ”.

Diagnosis. Colony branched in one plane, with some parts anastomosing and branches tapered at the tip. Branching irregularly, at acute angles near the base and almost right angles near the top of the colony. Coenenchymal mounds distributed on one side of the colony, 2–3 mm intervals at the base, less than 1 mm on the twigs, 1.14–1.60 mm in diameter and 0.47–0.65 mm in height. Coenenchyme is 0.13–0.19 mm thick in the dry condition, with small but distinct warts on all side of the colony, pinkish white in colour. Axis stout, no depressions underneath coenenchymal mounds, finely striated 0.26–0.33 mm interval in the longitudinal direction, white in colour. Double-clubs are most abundant, 6-radiates are common, 7-radiates, crosses and rods are rare.

Description of the holotype:

Colony form: The specimen is an almost whole colony with a holdfast, but one of the main branches and some branch portions are missing ( Fig. 18). The colony is about 170 mm tall and 95 mm wide and is branched in one plane with some parts anastomosing. A part of the coenenchyme encrusts foreign calcareous matter. Branches occur irregularly and are tapered at the tips. Their angle of branching is acute near the base, but at almost right angles near the top of the colony. The diameter at the base of the colony is about 20 mm, the main stem is 12 mm, and thinnest branch tip is about 4–5 mm. Branch cross sections are rounded ( Fig. 20).

Polyps: Originally retracted into the coenenchyme, making hemispherical coenenchymal mounds, the autozooid tissue has now completely disintegrated. The coenenchymal mounds are distributed on one side of the colony ( Fig. 19), 1.14–1.60 mm in diameter and 0.47–0.65 mm in height. They are distributed at 2–3 mm intervals at the base, but are more crowded on the twigs where they are generally less than 1 mm apart, with some are almost touching ( Fig. 18). The mean distance apart is 2.14 mm. Siphonozooids are invisible to the naked eye but form small pits on the surface of the coenenchyme, 0.04–0.08 mm in diameter, and are irregularly distribution on both “front” and “back” sides of the branches ( Fig. 19).

Axis: The surface of the axis is faintly longitudinally striated ( Fig. 21), at intervals of 0.26–0.33 mm, and covered with minute tubercles ornamented with thorny projections ( Fig. 22). There is no rounded pit on the axis at the position of each coenenchymal mound ( Fig. 21).

Coenenchyme: This is 0.13–0.19 mm thick ( Fig. 20) and the longitudinal axial grooves are not visible through it. Small but distinct warts sized 0.11–0.21 mm in diameter are present on “front” and “back” sides of the branch ( Fig. 19), evenly distributed at 0.13–0.35 mm intervals.

Colour: The dry coenenchyme is pinkish white, coenenchymal mounds and branch tips becoming darker ( Fig. 19). Axis is white ( Fig. 20).

Sclerites: The coenenchymal mounds contain mainly double-clubs with a rough surface 0.041 –0.065 mm long and 0.030 –0.054 mm wide, symmetric 6-radiates 0.035 –0.075 mm long and 0.024 –0.048 mm wide, and asymmetric 6-radiates 0.041 –0.064 mm long and 0.028 –0.049 mm wide; small 6-radiates and 7-radiates are rare ( Fig. 23A). The coenenchyme on the branch tip contains mainly double-clubs with a rough surface 0.039 –0.061 mm long and 0.029 –0.049 mm wide, asymmetric 6-radiates 0.039 –0.069 mm long and 0.029 –0.052 mm wide, and symmetric 6-radiates 0.039 –0.077 mm long and 0.034 –0.050 mm wide: small 6-radiates, 7-radiates and rods are rare ( Fig. 23B). The coenenchyme on the base of the colony contains mainly double-clubs with a rough surface 0.039 –0.059 mm long and 0.033 –0.048 mm wide, symmetric 6-radiates 0.043 –0.081 mm long and 0.029 –0.054 mm wide, asymmetric 6-radiates 0.045 –0.070 mm long and 0.035 –0.050 mm wide, and rarely 7-radiates and crosses ( Fig. 23C). The statistical data for the sclerite measurements for this specimen are shown in Table 6.

The average size of the double-clubs with a rough surface is almost the same from the three parts of the specimen. Asymmetric 6-radiates from the three parts are also similar in size. The average size of symmetric 6- radiates from the coenenchymal mounds is the smallest of the three areas sampled.

Relative abundance of sclerites ( Fig. 24, Table 6): There are seven kinds of sclerites in the coenenchyme of the holotype. In the coenenchymal mounds, double-clubs with a rough surface represent 68% of the sclerites, symmetric 6-radiates 18%, and asymmetric 6-radiates 11%. In the branch tips, double-clubs with a rough surface represent 57% of the sclerites, asymmetric 6-radiates 22%, and symmetric 6-radiates 19%. In the base of the colony, double-clubs with a rough surface represent 52% of the sclerites, symmetric 6-radiates 31%, and asymmetric 6-radiates only 14%.

The percentage makeup of the sclerites is similar in all three parts of the specimen. The most abundant sclerites are double-clubs with a rough surface, composing 52–68%. On the branch tip, symmetric and asymmetric 6-radiates occur in almost the same ratio. In coenenchymal mounds and colony base, symmetric 6-radiates are much more abundant than asymmetric ones. Small 6-radiates, and 7-radiates, rods and crosses are rare in all parts of the specimen.

Etymology: Named for the region from which it was collected, the Goto Islands, Nagasaki, Japan. The Goto Islands were one of the largest fishing grounds of precious corals in Japan, and many coral boats were sunk by typhoons: 300 fishermen died in 1895; 10 fishermen died, 209 were missing and 155 boats sank in 1905; 119 fishermen died, 615 were missing and 173 boats sank in 1906; and 64 men died and 30 boats were missing in 1914 ( Kosuge, 1987). This scientific name is offered to the souls of fishermen who sacrificed their lives.

Remarks: There are four species having hemispherical coenenchymal mounds distributed on the “front” of the colony, and whitish coenenchyme and axis (Table 8): C. konojoi ; C. medea Bayer, 1964 ; C. niveum Bayer, 1956 ; P. thrinax Bayer, 1996 . But C. medea and C. niveum have abundant 8-radiates and P. thrinax has smooth doubleclubs, not characteristics fitting USNM 19928. The most remarkable character of C. konojoi is having clusters of coenenchymal mounds on the branch tip ( Kishinouye 1903a,b, 1904a,b), another feature not present in USNM 19928.