Sympodium epiphytum, Benayahu & Ekins & Mcfadden, 2021

Benayahu, Yehuda, Ekins, Merrick & Mcfadden, Catherine S., 2021, Overview of the genus Sympodium Ehrenberg, 1834 (Octocorallia, Alcyonacea, Xeniidae), with the description of new species, revealing regional endemism, Zootaxa 5072 (4), pp. 324-350 : 334-335

Sympodium epiphytum sp. n.

Figs. 6 , 7

Material. Madagascar. Syntypes: SMNHTAU_Co_36010, Ankaréa (12°50.054’S, 48°34.563.3’E), 24–26 m, 29 November 2012, coll. Y. Benayahu ; Paratypes: SMNHTAU_ Co _35977, Riva Be (12°59.126’ S, 48°34.453’E), 8–10 m, 27 November 2012, coll. Y. Benayahu ; SMNHTAU_ Co _ 36062, 4 Fréres (12°59.655’S, 48°29.248’E), 4–15 m, 1 December 2012, Coll. Y. Benayahu.

Description. The syntypes comprise several small encrusting colonies up to only 5 x 5 mm. They are densely growing on thin branched algal material which easily fragments ( Fig. 6A ). Some of the colonies are connected by their thin spreading membrane, and therefore it is not practical to separate a single colony as a holotype. The small size of the syntypes is also reflected by the fact that each comprises only 4–12 polyps ( Fig. 6B ). The polyps are expanded and their body measures up to 2.5 mm. The tentacles are approximately 1 mm long and feature one row of 7–9 pinnules on either side. The pinnules are slender and pointed, up to 0.25 mm long.

The sclerites of the syntypes are ellipsoid platelets, highly abundant throughout the colony, measuring 0.011 – 0.012 x 0.015 –0.017 mm in diameter ( Fig. 7A ). They are composed of calcite rods whose tips mostly provide a granular appearance to the sclerite surface ( Fig. 7B ).

Color. The ethanol-preserved colonies are cream.

Etymology. The species’ name is derived from the ancient Greek “epiphúton”, one [plant] that grows upon another plant (epí, “on top of”) + (phutón, “plant”), via epi- (“above, over”) + - phyte (“plant”). It denotes the nature of the colonies found growing on algal material.

Variation. The paratypes SMNHTAU_Co_35977 (not shown) and SMNHTAU_Co_ 36062 ( Fig. 6C ) are similarly attached to algal fragments. Some of the colonies are larger than those of the syntypes, up to 8 x 8 mm ( Fig. 6D ). Their sclerites are similar to those of paratype SMNHTAU_Co_36062 ( Fig. 7C ), with a surface that features calcite rods ( Fig. 7D ) that are more densely packed than those of the holotype ( Fig. 7B ).

Remarks. The epiphytic nature of the colonies is suggested to be diagnostic for this species The syntypes and a paratype were sequenced and subsequently assigned to MOTU37 ( McFadden et al. 2019).

Distribution. Madagascar.

Figures

FIGURE 6. Sympodium epiphytum sp. n.: morphology of type material. (A) Syntypes (SMNHTAU_Co_36010) are encrusting colonies growing on thin branched algal fragments. (B) Several syntypes interconnected by a thin spreading membrane. (C) Paratype (SMNHTAU_Co_35977) growing on algal material. (D) Higher magnification of several paratype colonies.

FIGURE 7. Scanning electron micrographs of sclerites of Sympodium epiphytum sp. n.: Syntypes (SMNHTAU_Co_36010): (A) Ellipsoid platelets. (B) Tips of calcite rods provide a uniform granular appearance to the sclerite surface. Paratype (SMNHTAU_ Co_35977): (C) Ellipsoid platelets. (B) Tips of calcite rods provide a uniform granular appearance to the sclerite surface.