Hemicorallium muzikae Nonaka & Hayashibara 2021, sp. nov.
Creators: name: Nonaka, Masanori
name: Hayashibara, Takeshi
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Cnidaria
Anthozoa
Alcyonacea
Coralliidae
Hemicorallium
Hemicorallium muzikae

description: Hemicorallium muzikae sp. nov.   (Figs 49–56; Tables 2, 7)  
 Material examined. Holotype, NSMT-Co 1738, Colahan Seamount, 682–712 m, 2 August 2012.   
 Diagnosis. Colony may branch almost in one plane, with some anastomoses, but the whole colony form is unknown. Branching irregular, almost acute angles. Contract- ed autozooids are concentrated on one side of the colony, interpolypary distance 1.1–3.7mm, diameter 0.9–1.3 mm (average 1.08 mm) and height 0.7–1.3mm (average 0.99 mm). Coenenchyme is 0.09–0.18 mm (average 0.13 mm) thick in the dry condition, with small warts, pale pink in color. Axis pink, stout, with longitudinal grooves, many commensal burrows, no depressions underneath autozooids. Tentacles contain rods about 0.1 mm long, coenenchyme contains mainly 8-radiates, 6-, 7-, multi-radiates are present, doubleclubs are absent.   
 Description of the holotype. Colony form. The specimen consists of two twigs (Fig. 49). One is 80 mm long and 60 mm wide, the other about 60 mm long and 60 mm wide. Diameter is 5–10 mm at the branch base, 1–2 mm terminally (Fig. 49). Branching may be almost planar, with some anastomoses, but colony form is unknown. The angle of branching is irregular, almost acute (Fig. 49).   
Polyps. The autozooids are not retracted into the coenenchyme, making cylindrical mounds with 8 conspicuous longitudinal striations (Fig. 52). They are present on only one side of the colony, absent on the opposite side (Fig. 50), tending to concentrate on the terminal twigs, but not making clusters (Fig. 51). They measure 1.08± 0.09 mm in diameter and 0.99± 0.20 mm in height (Fig. 52; Table 2). Interpolypary distance is 1–3.5 mm on the twigs (Fig. 52). Siphonozooids (0.08± 0.03 mm in diameter) are sparsely distributed on the basal parts of the autozooids (Fig. 52; Table 2).  
Axis. The surface of the axis is almost smooth, having shallow longitudinal grooves about 0.32 mm apart (Fig. 53; Table 2). There are no rounded pits on the surface of the axis at the positions of autozooids. Many polychaete burrows are present in the axis (Fig. 51).  
Coenenchyme. Coenenchyme is very thin, 0.13± 0.02 mm thick, covering the axis (Fig. 54; Table 2). Warts (about 0.23 mm in diameter) are visible on the surface (Figs 51, 52), tending to line up longitudinally. On the twigs they become raised ridges (Fig. 52), especially on the side without autozooids. At high magnifications, the gastrovascular system is visible through the thin coenenchyme (Fig. 54). This thin coenenchymal “curtain” covers the burrows of commensal worms (Fig. 51).  
Color. The dry coenenchyme is pale pink, the axis is a deeper pink color (Figs 49–54).  
Sclerites. The tentacles contain mainly rods (37%; 0.092± 0.017 mm long, 0.024± 0.005 mm wide), multi-radi- ates (29%; 0.079± 0.013 mm long, 0.033± 0.005 mm wide) and a few 6-radiates, 7-radiates and 8-radiates (Figs 55, 56; Table 7).  
The autozooid mounds contain mainly symmetric 8-radiates (45%; 0.068± 0.008 mm long, 0.041± 0.004 mm wide), asymmetric 8-radiates (19%; 0.071± 0.006 mm long, 0.044± 0.003 mm wide), 7-radiates (19%; 0.065± 0.003 mm long, 0.042± 0.003 mm wide), and a few 6-radiates and multi-radiates (Figs 55, 56; Table 7).  
The branch tips contain mainly symmetric 8-radiates (37%; 0.059± 0.009 mm long, 0.037± 0.005 mm width), asymmetric 8-radiates (32%; 0.056± 0.004 mm long, 0.038± 0.003 mm width), and a few 6-radiates, 7-radiates, multi-radiates, others (Figs 55, 56; Table 7).  
Basal coenenchyme contains mainly symmetric 8-radiates (46%; 0.058± 0.005 mm long, 0.037± 0.003 mm wide) and asymmetric 8-radiates (35%; 0.056± 0.005 mm long, 0.037± 0.003 mm width), 7-radiates (13%; 0.056± 0.006 mm long, 0.036± 0.003 mm width), with a few crosses, 6-radiates and multi-radiates (Figs 55, 56; Table 7).  
 Etymology. This species is named in honor of Dr. Katherine Muzik, scientist and octocoral researcher for over 50 years (since 1970). She studied taxonomy, including of the Coralliidae, with Dr. Frederick Bayer, and conducted field research on octocorals worldwide, especially in the Caribbean, Fiji, the Hawaiian Islands, Okinawa and Japan. Her excellent studies have greatly supported our research on octocorals.   
 Remarks. Because specimen NSMT-Co 1738, has nonretracted, cylindrical autozooids (Fig. 52), slender rodshaped sclerites in the tentacles (Fig. 55), and lacks rounded pits on the axis at the position of each autozooid, this specimen is placed in the genus Hemicorallium.   
 There are only two species of Hemicorallium previously described from the Pacific having small (about 1.0 mm in both height and diameter) contracted autozooids: H. laauense and H. taiwanicum. The two other new species described in this study, H. kaiyo sp. nov. and H. tokiyasui sp. nov., have similarly sized autozooids, but differ in sclerite composition (both 6-radiates and 8-radiates present) from H. muzikae sp. nov. (8-radiates dominant). Hemicorallium taiwanicum differs in color (dark-pink coenenchyme and orange axis) and contains predominantly double-club sclerites in its coenenchyme (Tu et al. 2012). Hemicorallium laauense and H. muzikae sp. nov. have similar sclerite composition, but differ in color of axis and coenenchyme. Additionally, the rod-shaped sclerites of H. laauense are reportedly much larger (0.145 mm) (Bayer 1956) than those of H. muzikae (0.092 mm).
description: Published as part of Nonaka, Masanori & Hayashibara, Takeshi, 2021, A Report on Coralliidae (Cnidaria: Octocorallia) Specimens Collected from the Emperor Seamounts with Descriptions of Three New Species, pp. 297-342 in Species Diversity 26 on pages 330-331, DOI: 10.12782/specdiv.26.297, http://zenodo.org/record/5739111