Corallium konojoi Kishinouye, 1903

Nonaka, Masanori, Muzik, Katherine & Iwasaki, Nozomu, 2012, 3428, Zootaxa 3428, pp. 1-67 : 36-42

Corallium konojoi Kishinouye, 1903 ( Figs. 28–34; Tables 9, 10)

Corallium konojoi Kishinouye, 1903a: 625 ; Kishinouye 1903b: 105 (in Japanese); Kishinouye 1904a: 27, pl. 1, fig. 4; pl. 7, fig. 5; pl. 8, figs. 16, 17 (in Japanese); Kishinouye 1904b: 26, pl. 1, fig. 4; pl. 7, fig. 5; pl. 8, figs. 16, 17; Kuekenthal 1924: 50; Bayer, 1956: 76 (in key); Grigg 1984: 59; Harper 1988?: 50; Imahara 1996: 28 (in list); Nonaka et al. 2006: 1824, figs. 6– 8; Nonaka & Muzik 2010: 94–95, figs. 15, 16.

Material examined: Neotype (designated herein), USNM 19929 , Murotsu , Tosa , Japan. The sample was donated and identified by Kishinouye, and was later erroneously labelled “ syntype.”

Diagnosis. Colony sparingly branched, generally in one plane with branches often anastomosing and branch tip blunt and rounded. Coenenchyme thick and firm with a relatively smooth surface and yellowish to reddish in colour, becoming lighter towards the holdfast. Coenenchymal mounds relative large, 1.3 mm in diameter and a little elevated, unevenly distributed on one face of the colony and clustered in groups forming prominences on the branch tip. Axis grooved and milky white with a pinkish center. Sclerites comprised of 6-radiates, which are about 0.05 mm long and the most abundant sclerite; 7- and 8-radiates, which are very rare; and double-clubs.

Description of the neotype:

Colony form: The specimen is an almost complete colony (some branch tips are missing) with a holdfast and a portion of the substratum (limestone rock) attached ( Fig. 28). The colony is about 90 mm tall and 47 mm wide and branched almost in one plane. Branches are blunt and rounded at the tip, without anastomoses, and the angle of branching is at mostly 45 degrees. The diameter at the base of the colony is about 20 mm, the main stem is 10 mm, the thickest branch is about 7 mm (without polyp mounds), and the thinnest branch tip is about 5 mm. Branch cross sections are rounded.

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 only ( Fig. 29) and some are in clusters ( Fig. 30), especially on the twig tips. They form low mounds, 1.19–1.41 mm in diameter, with an 8-lobed aperture. Siphonozooids form small pits on the surface of the coenenchyme, 0.03–0.12 mm in diameter. On the “front” side of the branches, they are rather crowded (0.44–1.41 mm apart) around the polyp mounds, but on the “back” side, they are distributed randomly (0.75–1.63 mm apart) ( Fig.29).

Axis: The surface of the axis is longitudinally grooved at intervals of about 0.2 mm ( Fig. 31) and covered with minute tubercles ornamented with thorny projections ( Fig. 32). At the position below each coenenchymal mound, there is a mound on the axis ( Fig. 31).

Coenenchyme: About 0.33 mm thick and relatively smooth, without bumps or depressions ( Figs. 29, 30).

Colour: The general coenenchyme is white to pale pinkish-white ( Figs. 28–30), but the coenenchymal mounds are reddish ( Fig. 30). The axis is white.

Sclerites: The coenenchymal mounds contain mainly symmetric 6-radiates 0.031 –0.060 mm long and 0.027 – 0.049 mm wide, asymmetric 6-radiates 0.040 –0.055 mm long and 0.031 –0.045 mm wide, double-clubs with a rough surface 0.036 –0.057 mm long and 0.030 –0.048 mm wide, and a few smooth double-clubs: small 6-radiates and 7-radiates are rare ( Fig. 33A). The coenenchyme on the branch tip contains mainly double-clubs with a rough surface 0.040 –0.051 mm long and 0.034 –0.045 mm wide, symmetric 6-radiates 0.041 –0.067 mm long and 0.026 – 0.049 mm wide, asymmetric 6-radiates 0.041 –0.061 mm long and 0.035 –0.049 mm wide, and double-clubs with a smooth surface 0.041 –0.055 mm long and 0.036 –0.046 mm wide: small 6-radiates are very rare ( Fig. 33B). The coenenchyme on the base of the colony contains mainly symmetric 6-radiates 0.047 –0.076 mm long and 0.036 – 0.055 mm wide, double-clubs with a smooth surface 0.043 –0.053 mm long and 0.037 –0.051 mm wide, doubleclubs with a rough surface 0.042 –0.059 mm long and 0.036 –0.052 mm wide, and a few asymmetric 6-radiates ( Fig. 33C). The statistical data for sclerites of this specimen are shown in Table 9.

Six-radiates from the base tend to be larger than those from the branch tips, while those from the coenenchymal mounds are the smallest of the three regions sampled. However, double-clubs (both rough and smooth) are almost the same size in all regions (Table 9).

Relative abundance of sclerites ( Fig. 34; Table 9): There are 6 kinds of sclerites in the coenenchyme of the neotype. In the coenenchymal mounds, symmetric 6-radiates represent 53% of the sclerites, asymmetric 6-radiates 25%, and double-clubs with a rough surface 14%. In the branch tip, double-clubs with a rough surface represent 34% of the sclerites, symmetric 6-radiates 28%, asymmetric 6-radiates 21%, and double-clubs with a smooth surface 16%. In the base, symmetric 6-radiates represent 37% of the sclerites, double-clubs with a smooth surface 33%, double-clubs with a rough surface 22%, and asymmetric 6-radiates only 9% (Table 9).

Symmetric and asymmetric 6-radiates are the most abundant form in the coenenchymal mounds, whereas double-clubs (both rough and smooth) are the most abundant sclerites in the branch tip and in the base ( Fig. 34). Seven-radiates and 8-radiates are rare, and small 6-radiates and rods are completely absent from the whole colony except for the coenenchymal mounds. Although double-clubs with a rough surface are more abundant than smooth ones in the coenenchymal mounds and branch tip (14% and 34% rough; 4% and 34% smooth), at the base, doubleclubs with a smooth surface are more abundant (33%) than those with a rough surface (22%). Small 6-radiates, and 7-radiates are rare (composing less than 2%). The relative abundance of different kinds of basal sclerites is significantly different from other species examined in this study ( Table 3; Chi-square test, p<0.001).

Remarks: USNM 19929 is mysteriously labelled “ syntype ”, not in Kishinouye’s handwriting. Kishinouye (1903a,b, 1904a,b) described the first specimens of this species, but without selecting a holotype, and also without mention of this particular specimen, which, however, was collected and identified by him. Also he described only its “distribution”, not a specific locality, as the southwestern coast of Kyushu, and off the southern coasts of Kochi and Wakayama ( Kishinouye 1904b). USNM 19929 was collected from the region he described as “Murotsu, Tosa (the old name for Kochi).” This specimen, preserved at the National Museum of Natural History, Smithsonian Institution has been selected here as the neotype to fix the identity of the species, C. konojoi Kishinouye, 1903 . This species resembles C. borneense Bayer, 1950 , C. niveum Bayer, 1956 and C. pusillum Kishinouye, 1903 , in the presence of thicker coenenchyme and clusters of coenenchymal mounds. However a colony of C. borneense branches on all sides while C. konojoi branches in one plane. C. niveum and C. pusillum can be distinguished from this species using the coenenchyme color ( C. niveum : white, C. pusillum : orange, while C. konojoi is pale yellow with reddish tips) and the presence of 8-radiate sclerites (neotype of C. konojoi has no 8-radiates).

Kishinouye described coenenchymal mounds 2–3 mm in diameter, but in this specimen they are about half that size (1–1.5 mm). Was Kishinouye reporting measurements of polyp clusters?

He recorded four kinds of sclerites, 8-radiates, 6-radiates, 7-radiates and double clubs ( Kishinouye 1904a,b), but we could find no 8-radiates in the neotype ( Fig. 34). In his description, 6-radiates were 0.09 mm long, much larger than the 6-radiates of this specimen. We re-examined ten additional specimens collected from the Southern Kagoshima region, Japan, which we have identified as this species by confirming the length of 6-radiates and the presence of 8-radiates (Table 10). Our measurement data suggests that Kishinouye made mistakes in measurements of lengths of 6-radiates, or that he was reporting the maximum, not average length. There are indeed 8-radiates occurring in the coenenchyme of some specimens of this species but they are very rare and not found in all specimens .