Thesea pyrrha, Carpinelli & Cordeiro & Castro & Kitahara, 2022

Carpinelli, Ágatha Nascimento, Cordeiro, Ralf Tarciso Silva, Castro, Clovis Barreira & Kitahara, Marcelo Visentini, 2022, Thesea pyrrha sp. nov., a new shallow-water octocoral (Cnidaria, Anthozoa) from southwestern Atlantic, and implications on the systematics of the genus, Zootaxa 5116 (1), pp. 89-106 : 96-101

Thesea pyrrha sp. nov.

Thesea sp. : Tixier-Durivault, 1970, p. 152 –153, fig. 3 (MNHN paratype).— Castro et al., 2006, p. 175 (station list).

Holotype. USNM 73349 , 23°12'21"S, 44°31'36"W, Ilha Grande Bay , Rio de Janeiro, Brazil, collected by Clarisse Rohlfs, 04/29/1980.

Paratypes. MNHN (accession number unavailable), Calypso st. 100, 22°12,5'S, 40°59'W, off Cape São Tomé, Rio de Janeiro, 39 m (fragment) ; MNRJ 5078 , 22°19’07” S, 40°49’34” W, off Macaé , Rio de Janeiro, 57–60 m ; MNRJ 2641 , 22°25'S, 41°05'W, off Macaé, Campos Basin , 51 m (one colony) ; MNRJ 1377 , Laje de Santo Antônio, off Ipanema Beach , Rio de Janeiro, 10 m (4 colonies) ; MNRJ 1979 , Laje de Santo Antônio, off Ipanema Beach , Rio de Janeiro, 10 m (6 colonies) ; MNRJ 333 (between 23°11,5'S, 44°28,3'W and 23°13,2'S, 44°34,9'W), Ilha Grande Bay , Rio de Janeiro, 30 m (two colonies) ; USNM 1659638 , 23°12'21"S, 44°31'36"W, Ilha Grande Bay , Rio de Janeiro, Brazil (same collection data of the holotype) ; MNRJ 1859 , Xavier Island, Florianópolis , Santa Catarina, 19 m (one colony) ; MNRJ 2474 , Arvoredo Island, Florianópolis , Santa Catarina, 3 m (two colonies) ; MNRJ 4876 , 23°03’S, 43°92’W Cagarras Archipelago, Rio de Janeiro, shallow-water (fragment) ; USNM 51601 , between Rio Grande and Chuí , Rio Grande do Sul, Pascal II R/V; MZUSP 8699 , 27°16’S, 48°22’W, Arvoredo Island , Florianópolis, Santa Catarina, shallow-water (fragment) ; MZUSP 8700 , 28°45’S, 48°71’W, Lobos Island , Santa Catarina, shallow-water (one colony) ; MZUSP 8701,28°45’S, 48°71’W, Lobos Island , Santa Catarina, shallow-water (four colonies) ; MZUSP 8702 , 28°45’S, 48°71’W, Lobos Island , Santa Catarina, shallow-water (two colonies) ; MZUSP 8703 , 28°45’S, 48°71’W, Lobos Island , Santa Catarina, shallow-water (two colonies) ; MZUSP 8704 , 28°45’S, 48°71’W, Lobos Island , Santa Catarina, shallow-water (one colony) ; MZUSP 8705 , 28°45’S, 48°71’W, Lobos Island , Santa Catarina, shallow-water (one colony) ; MZUSP 8706 , 28°73’S, 49°02’W, Laje da Jaguaruna , Santa Catarina, shallow-water (three colonies) .

Description. Colonies white, yellow, orange or red, 3 to 10 cm tall and 3 to 9 cm in width, planar to sparsely bushy ( Figs. 1A , 3 ). Branches oriented upwards up to the 6 th order, terminal branchlets between 0.5–6.7 cm long. Main branch from 2.5 to 18 cm long and from 5 to 15 mm in width. Proximal diameter of branches of 1.6–2.8 mm, and 1.2–2.1 mm distally. Branch thickness varying from slender proximally to thicker in the median portion; tips rounded and slightly slender. Polyps only on branches, disposed in four main alternate rows, sometimes irregular. Calyces ( Fig. 1 C-D) usually low and sometimes absent, with eight marginal teeth, formed by convergent spindles. Sometimes calyces may have up to 0.9 mm in height and 1 mm in diameter. Coenenchymal surface with two-faced sclerites, externally corrugated and internally densely filled with tubercles ( Figs. 1B , 2A ), 0.34–0.6 mm long and 0.03–0.25 wide, disposed side by side, creating a surface with granulose appearance ( Fig. 1C ). Two-faced sclerites of the outer layer interleaved by uniformly tuberculated spindles 0.23–0.26 mm long ( Fig. 2B, D ). Calyces with smaller sclerites, often slender than those from coenenchyme, mostly tuberculated spindles and clubs ( Fig. 1C ) up to 0.24 mm in length. Inner coenenchymal layer with tuberculated spindles ( Fig. 2E ) 0.12–0.23 mm long and 0.02–0.11 wide. Polyp sclerites are spindles and rods straight or curved ( Fig. 2F ), 0.06–0.28 long and 0.001–0.01 mm wide.

Habitat and distribution. Brazil, off Rio de Janeiro, Santa Catarina and Rio Grande do Sul (22° to 33°S) on shallow to mesophotic hard substrates (3 to 60 m).

Etymology. The species epithet pyrrha (Gr. pyrrhos, flame-colored, red, yellowish-red), alludes to the flamecolored color of live specimens that range from vivid-red to yellowish-red.

Comparative materials. Thesea gracilis (MCZ 4160, holotype); T. bicolor ( MCZ 4626 , holotype) ; T. granulosa ( MCZ 4624 , holotype) ; T.rubra ( MCZ 4627 , holotype) ; T. citrina Deichmann, 1936 ( MCZ 4632 , holotype) ; T.rugosa Deichmann, 1936 ( MCZ 4633 , syntype) ; T. parviflora Deichmann, 1936 ( MCZ 4635 , holotype) ; T. grandiflora Deichmann, 1936 ( MCZ 4641 , syntype) ; T. hebes Deichmann, 1936 ( MCZ 4642 , syntype) ; T. antiope ( USNM 50848 , holotype) .

Remarks. Thesea pyrrha sp. nov. differs from Thesea antiope by not having the doublehead sclerites in the surface of the coenenchyme. Thesea gracilis ( Gray, 1868) , T. guadalupensis ( Duchassaing & Michelotti, 1860) and T. bicolor have more or less regular elongate sclerites in the coenenchyme, in which the outer face is sparsely granular. Thesea citrina , T. rugosa, T. grandiflora and T. parviflora have a similar granular sculpture pattern on their large plate-like coenenchymal sclerites. In Thesea hebes , its outer surface corresponds to the smaller portion of the sclerite, with a smooth surface as well. Thesea rubra has a nearly smooth outer surface. On the other hand, T. granulosa has stout sclerites in the outer coenenchyme, with tubercles fused in groups, but rarely forming projecting ridges. Interestingly, specimens obtained from greater depths (e.g. MNHN, 39 m; MNRJ 2641, 51 m) tend to have more prominent calyces than those from shallower waters (<20 m), in accordance with previous findings for other octocoral taxa (Grigg, 1970; West et al., 1993; Kim et al., 2004; Joseph et al., 2015).

In this manuscript, we prioritize the description of T. pyrrha and discussions are limited to the systematics of the genus Thesea . For that reason, we choose to keep it in the formal family Plexauridae , rather than describing a new family, for which purpose a morphological assessment of the genera Adelogorgia, Psammogorgia, and Swiftia would be necessary.

Molecular analyses

The sequencing of the samples of Thesea pyrrha sp. nov. resulted in partial fragments of the mitochondrial genes mtMutS (~590 bp) and COI+igr (~600 bp) and of the nuclear 28S rDNA (~560 bp). Most samples had only mtMutS and COI+igr successfully sequenced, but the samples 8699, 8700 and 8702 had all three regions determined. The concatenated alignment totaled 2.055bp, which were partitioned according to the best nucleotide evolutionary model as: HKY+G (mtMutS), HKY+I+G (COI), and GTR+G

(28S).

Gorgoniidae

The species traditionally included in the family Gorgoniidae were recovered in different arrangements in each phylogenetic reconstruction. The ML topology recovered a large gorgoniid clade with low statistical support ( Fig. 4 ). On the other hand, the BI recovered four main clades containing gorgoniids, all with Leptogorgia representatives (mostly not identified to species level). The clade named “ Gorgoniidae ” ( Fig. 4 ) is the only monophyletic clade of the family recovered by ML. This clade is composed by Leptogorgia, Antillogorgia, Eugorgia, Gorgonia, Pacifigorgia, Phyllogorgia, and Pseudopterogorgia.

Plexauridae

Morphologically identified plexaurids grouped into a large clade with high statistical support ( Fig. 4 ), being composed by Alertigorgia, Iciligorgia, Menella, Muricea, Muriceopsis, Paraplexaura, Pinnigorgia, Plexaura, Plexaurella Pseudoplexaura, Pterogorgia, and Siphonogorgia. The clade Bebryce-Lytreia-Heterogorgia was strongly supported and recovered in all reconstructions. Eunicella (traditionally Gorgoniidae ) was also recovered in all analyzes closer to Plexauridae .

Adelogorgia, Psammogorgia, and Thesea

Swiftia simplex falls into a sister clade of Psammogorgia spp. and Adelogorgia, which was monophyletic in all systematic reconstructions. These genera are also closely related to Swiftia and a namely Thesea sp. from Honduras ( AY683089 ). Adelogorgia, Psammogorgia, and Swiftia were related to Thesea pyrrha sp. nov. in all analyzes.

Specimens of Thesea sp. ( AY683083 – Galapagos, and KP324345 – New Caledonia) fall in clades distant from all Eastern Pacific and Atlantic congeners in all analyzes and need to be re-examined taxonomically. Sequences of the specimen from Galapagos AY683083 are identical to that from Euplexaura sp. ( GQ342518 ), whereas that from the New Caledonian specimen was also somewhat similar and, thus, recovered as closely related. Specimens of Thesea from Brazil were recovered as a monophyletic group with high-statistical support in all analyzes. They had in Thesea sp. ( MF319967 – Eastern Pacific) their sister clade. Results from the p- distance analyzes indicate that Psammogorgia is the genus closest to Thesea (0.096). Interspecific distances between sequences of Thesea sp. nov. vary from 0 to 0.360 ( Table 1 - Sup. Material).

Figures

FIGURE 1. Thesea pyrrha sp. nov. (USNM 73349, holotype). A: colony in stereo view; B: Large two-faced sclerite in stereo view; C, D: details of the calyces in stereo view.

FIGURE 2. Sclerites of Thesea pyrrha sp. nov. (USNM 73349, holotype). A, B: Double-faced sclerites of the outer coenenchymal layer; C: spindles of the calyces; D: spindles-like sclerites of the outer coenenchymal layer; E: spindles of the inner coenenchymal layer; F: polypar sclerites.

FIGURE 3. Images A and B shows Thesea pyrrha sp. nov. in situ. All photographed in Santa Catarina State, Brazil. Photos: Edson Faria Júnior.

FIGURE 4. Phylogeneticreconstruction with Maximum likelihood (left) and Bayesian Inference (right) of the families Gorgoniidae and Plexauridae based on the concatenated dataset (mtMutS + COI+ 28S), including (purple) Thesea pyrrha sp. nov.