Sunday, June 18, 2017

[Cnidaria • 2017] Altumia delicata • A New Sclerite-Free Genus from Eilat, northern Red Sea [Search for Mesophotic Octocorals (Cnidaria, Anthozoa) and Their Phylogeny]

Altumia delicata
Benayahu, McFadden & Shoham, 2017

This communication describes a new octocoralAltumia delicata gen. n. & sp. n. (Octocorallia: Clavulariidae), from mesophotic reefs of Eilat (northern Gulf of Aqaba, Red Sea). This species lives on dead antipatharian colonies and on artificial substrates. It has been recorded from deeper than 60 m down to 140 m and is thus considered to be a lower mesophotic octocoral. It has no sclerites and features no symbiotic zooxanthellae. The new genus is compared to other known sclerite-free octocorals. Molecular phylogenetic analyses place it in a clade with members of families Clavulariidae and Acanthoaxiidae, and for now we assign it to the former, based on colony morphology. The polyphyletic family Clavulariidae is, however, in need of a thorough revision once the morphological distinctions among its phylogenetically distinct clades are better understood.

Keywords: Octocorallia, new genus, taxonomy, mesophotic coral ecosystem, Eilat, Red Sea

Family Clavulariidae Hickson, 1894
Subfamily Clavulariinae Roxas, 1933

Altumia gen. n.

Diagnosis: Clavulariinae with a thin and soft encrusting base, sometimes resembling a short stolon. Polyps erect when expanded, separate from each other; the stolon may feature a few polyps, occasionally only one. Polyps fully retractile into base of the colony, forming low truncated dome-shaped mounds. No sclerites in any part of the colony. Colonies lack symbiotic algae (zooxanthellae). Type species: Altumia delicata sp. n. by original designation and monotypy.

Etymology: The generic name is derived from the Latin ‘altum’, deep, referring to the habitat of the new genus at MCE depths and beyond. Gender female.

Figure 2: Altumia delicata gen. n. sp. n. holotype ZMTAU CO 37427.
A Colony growing over a branch of a black coral B close up of holotype. Scale 10 mm at A, 1 mm at B. 

Altumia delicata sp. n.

 Holotype: ZMTAU CO 37427, Israel, Gulf of Aqaba, Eilat, 29°30'38.31"N, 34°55'59.30"E, 132 m, 30 May 2016, collected by ROV, coll. M. Weis; paratype: ZMTAU CO 37495, Israel, Gulf of Aqaba, Eilat, 29°30'37.29"N, 34°55'59.28"E, 118 m, 8 March 2017, collected by ROV, coll. M. Weis

Diagnosis: The ethanol-preserved holotype is comprised of thin patches of short stolon-like crusts growing over the dead branch of a black coral (Antipatharia) (Figure 2A), almost invisible to the naked eye. The milky-white, thin (<0.5 mm) crusts are a few mm long (Figure 2B), very soft, almost slime-like. Polyps completely retracted and practically invisible in the preserved colonies. No sclerites observed in any part of the colony.

Intraspecific variability: There are no differences between the holotype and the paratype except for the size of the colonies.

Etymology: The species name is formed from the Latin ‘delicata’, delicate, referring to the fine texture of the colonies and their polyps. Gender female.

Figure 3: Altumia delicata gen. n. sp. n. live colonies.
A, B colonies growing over branch of black coral with expanded polyps C colonies growing on PVC net (arrow heads). 

 Yehuda Benayahu, Catherine S. McFadden and Erez Shoham. 2017. Search for Mesophotic Octocorals (Cnidaria, Anthozoa) and Their Phylogeny: I. A New Sclerite-Free Genus from Eilat, northern Red Sea. ZooKeys. 680: 1-11.  DOI: 10.3897/zookeys.680.12727