Trichogorgia muzikae, Cordeiro, 2019

Cordeiro, Ralf T. S., 2019, A review of the genus Trichogorgia (Cnidaria, Octocorallia), including descriptions of new species, Zootaxa 4706 (4), pp. 517-530 : 522-526

Trichogorgia muzikae sp. nov.

Fig. 4–5 , 6D

Holotype: 24°25’12”N, 123°49’48”E, 25 m, Iriomote , Indabishi, Japan, coll. by Katherine Muzik on July 18 th 1982 ( USNM 77155 , one colony) ( Fig. 4D ).

Paratype: same collection data of the holotype ( USNM 77155 , three complete colonies) ( Fig. 4C ) .

Description: Small, delicate, uniplanar, flexible flabellate colonies, dichotomously branched, not lyrate, up to 2.8 cm tall and 4 cm wide. Colonies with attachment scars, but lacking calcareous holdfasts. Calcified axis, golden to pale yellow, circular in cross-section ( Fig. 4E ), layers concentric (not undulated) up to 0.5 mm in diameter. First order branchlets 0.8–3.3 mm long and internodes 3.0– 7.4 mm long. Polyps verruciform 0.18–0.23 mm tall and 0.2–0.3 mm wide when contracted, occurring in an alternate manner in two rows along branchlets and rarely on the main stem, slightly turned to one face of the colony, occurring in a density of 10–14 polyps/cm. Interpolypar distances from 0.17 proximally, decreasing to 0.04 mm towards branchlet tips. Sclerites present in both polyps and coenenchyme as very flattened smooth eight-shaped scales with a median waist. Main stem usually devoid of polyps and up to 4.6 mm long. Branchlets up to the 6 th order and terminal branches up to 20 mm long. Sclerites show a concentric extinction pattern under polarized light. Polyp body wall with up to eight rows of transversely oriented scales 55–100 µm long (81.87± 12.98 µm) and 25–41 µm wide (32.75± 4.86 µm), becoming more irregularly shaped and longitudinally oriented toward the oral portion ( Fig. 5A ). Tentacular scales longitudinally arranged, slightly more sculptured, elongate, usually lacking a median waist 50–92 µm long (70.57± 12.59 µm) and 15–27 µm wide (19.43± 4.35 µm) ( Fig. 5C ). Pinnular scales similar to small tentacular scales, but slightly less sclulptured ( Fig. 5D ). Coenenchymal sclerites broader than those from body wall, occurring on the entire axis and between zooids, 40–100 µm long (74.4± 16.06 µm) and 40–60 µm wide (48.6±5.27) ( Fig. 5B ).

Comparisons: Trichogorgia muzikae belongs to a group of species with conspicuous sclerites, which excludes T. capensis , T. lyra and T. utinomii sp. nov. The Southwestern Atlantic T. brasiliensis Castro, Medeiros & Loiola, 2010 and the Indian T. insulaeuropensis Weinberg, 2013 are similar in overall colony shape, differing from each other in the absence of coenenchymal sclerites in the latter. Both species differ from T. muzikae by having terminal branchlets usually reaching two-thirds of colony length; by showing dozens of sclerite rows around polyp body walls, more elongate irregular scales and some lacking median waist. In addition, scales are longitudinally placed in T. isulaeuropaensis , in contrast with the transversally arranged scales in T. muzikae . Trichogorgia flexilis Hickson, 1904 is morphologically closer, but yet different from the new species in having longitudinally arranged sclerites and dozens of sclerite rows in the body wall. Trichogorgia viola Deichmann, 1936 was described based on poorly preserved specimens and its description prevents comparisons either with the new species or with T. flexilis . The remaining proximal parts of T. viola (MCZ 4834— holotype) reach 6–9 cm in height, whereas complete colonies of T. muzikae are usually less than 3 cm tall. Further differences may arise pending a re-description of Deichmann’ species.

Remarks: Specimens are so small and delicate that they can easily be mistaken for hydroids, with which they share space.

Etymology: Named in honor to Dr. Katherine Muzik, who dedicated several years studying chrysogorgiids and also collected the specimens described herein.

Distribution: Known only from the type locality, Indabishi, Japan, 25 m.

Figures

FIGURE 4. Trichogorgia muzikae sp. nov. A, B (stereo): lateral view of polyps, showing their arrangement of scales in the body wall and position of the polyp in relation to the axis; C, D: colony view of the paratype (USNM 1580739) and holotype (USNM 77155) (C and D, respectively); E: axis in cross-section.

FIGURE 5. Sclerites of Trichogorgia muzikae sp. nov. (USNM 77155, holotype). A: broad scales from polyp body wall; B: scales from coenenchyme; C: tentacular elongate scales; D: pinnular scales.

FIGURE 6. Scale-shaped sclerites under polarized light showing concentric extinction patterns. A: Stephanogorgia diomedea (USNM 75108); B: Trichogorgia lyra (USNM 52875); C: S. wainwrighti (USNM 1112682); D: T. muzikae sp. nov. (USNM 77155, holotype).