On the reproduction of the solitary cold-water coral Fungiacyathus fragilis Sars, 1872 (Cnidaria: Scleractinia), and a new record in the SW Atlantic Ocean deep sea

Abstract

The first record of the solitary stony coral Fungiacyathus (Fungiacyathus) fragilis is reported from the southwestern Atlantic Ocean. Specimens were collected at the Mar del Plata submarine canyon in the Argentinian continental slope at 2419–3447 m depth during 2012 and 2013. The four specimens studied through histological sections were gonochoric. A high fecundity was recorded for one female (26,496 oocytes per polyp). The maximum size of oocytes was 786 µm suggesting lecitotrophic development, also no planulae were observed. Both previtellogenic and large vitellogenic oocytes were found in all females. Evidence of asexual reproduction was identified in corallum of a dried specimen.

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Coral Reefs (2024) 43:787–794
https://doi.org/10.1007/s00338-024-02488-7
NOTE
On thereproduction ofthesolitary cold‑water coral
Fungiacyathus fragilis Sars, 1872 (Cnidaria: Scleractinia),
andanew record intheSW Atlantic Ocean deepsea
RodrigoN.Calderón1 · PabloE.Penchaszadeh1·
DanielLauretta1
Received: 6 December 2023 / Accepted: 8 March 2024 / Published online: 29 March 2024
© The Author(s), under exclusive licence to International Coral Reef Society (ICRS) 2024
This species was recorded at a depth of 3578m (55.275°S;
58.942°W) during the USNS Eltanin expedition (1962).
Fungiacyathidae is a family of exclusively cold-water stony
corals constituted by only one genus, Fungiacyathus Sars,
1872. All species within this family are solitary and free-
living (i.e. not attached to the substrate), with flat base of
corallum. Fungiacyathids are found in all oceans at depths
of 69–6328m (Baron-Szabo etal. 2021), being the fam-
ily of scleractinian corals that inhabits deeper worldwide.
Fungiacyathus comprises 24 species (including two species
inquirenda) (Hoeksema and Cairns 2023) and is divided
into two subgenera: Fungiacyathus (Fungiacyathus), with
five cycles of septa and Fungiacyathus (Bathyactis) Mose-
ley 1880, with four cycles of septa. Fungiacyathus (Fun-
giacyathus) fragilis, known distribution includes records in
the North Atlantic (Norway, Cape Verde, Azores, eastern
coast of the USA) and in the Pacific (Hawaii, Australia, New
Zealand, and New Caledonia), at depths ranging from 200
to 2400m (Kitahara and Cairns 2021).
The reproductive biology of cold-water corals (CWCs)
is a clear global knowledge gap. Only a small fraction, less
than 4% of all known species, have documented aspects
of reproduction (Waller etal. 2023). Their relevance has
grown, since CWCs were designated as indicator taxa for
vulnerable marine ecosystem (VME) (FAO 2009). Many
of these species are ecosystem engineers that modify the
habitat, enabling the settlement of other species that can
use them as refuge and spawning sites (Buhl-Mortensen and
Mortensen 2004). Moreover, since CWCs frequently coexist
with commercially important fish species, fisheries pose a
risk factor for the viability of their populations (Clark etal.
2016).
Most studies on CWCs reproduction focus on the North
Atlantic Ocean, and only a few have been done in the
southern region (Waller etal. 2023). In Brazil, four reef
Abstract The first record of the solitary stony coral Fun-
giacyathus (Fungiacyathus) fragilis is reported from the
southwestern Atlantic Ocean. Specimens were collected at
the Mar del Plata submarine canyon in the Argentinian con-
tinental slope at 2419–3447m depth during 2012 and 2013.
The four specimens studied through histological sections
were gonochoric. A high fecundity was recorded for one
female (26,496 oocytes per polyp). The maximum size of
oocytes was 786µm suggesting lecitotrophic development,
also no planulae were observed. Both previtellogenic and
large vitellogenic oocytes were found in all females. Evi-
dence of asexual reproduction was identified in corallum of
a dried specimen.
Keywords Stony corals· Fungiacyathidae· Argentina·
Mar del Plata submarine canyon
Introduction
The total richness of stony corals (Cnidaria: Scleractinia)
within the Argentine Exclusive Economic Zone (AEEZ),
including the new record of Fungiacyathus (Fungiacyathus)
fragilis, consists of 23 species (Squires 1963; Cairns and
Polonio 2013; Schejter and Bremec 2015). Among them,
there is only one other species belonging to the family Fun-
giacyathidae Chevalier and Beauvais, 1987: Fungiacya-
thus (Bathyactis) marenzelleri (Vaughan, 1906) (Table1).
* Rodrigo N. Calderón
rodrigonicolascalderon@gmail.com
1 Museo Argentino de Ciencias Naturales “Bernardino
Rivadavia” – CONICET, Av. Angel Gallardo 470,
BuenosAires, Argentina
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