Polysyncraton, Nott, 1892

Oliveira, Livia M., Hoeksema, Bert W. & Rocha, Rosana M., 2019, Polysyncraton (Ascidiacea, Didemnidae): a re-examination of some specimens and descriptions of three new species, European Journal of Taxonomy 519, pp. 1-25 : 19-22

Polysyncraton sp.

Fig. 12

Material examined

BRAZIL • 1 colony; Rio de Janeiro, Cabo Frio, Pargos Island, Enseada do Pinguim ; 22°51′10″ S, 41°54′22″ W; ~ 10 m depth; 7 May 2014; L.F. Skinner leg.; DZUP POSC-033, slide DZUP DID5.29 .

Remarks

The colony is orange in situ, measuring 3 cm in diameter and 1 to 2 mm thick. The tunic is firm and gelatinous. The cloacal aperture has five lobes. The spicules are distributed in the colony surface only and are more concentrated around the oral siphon of each zooid. They are burr-like, with a large number of rays, 15 to 25 µm in diameter. The zooids are orange. The oral siphon is short, with six triangular lobes. The atrial aperture is wide, exposing almost all the pharynx, with 9, 9, 8, 8–7 stigmata per half row. The atrial languet is large and bifurcated. The lateral thoracic organ is circular, not protruding, located at the level of the 1 st row of stigmata. The muscular process is shorter than the abdomen, inserted in the middle of the esophageal peduncle. The testis is divided in four follicles surrounded by four coils of the sperm duct. Larvae were not found.

In the phylogenetic reconstruction ( Fig. 5 ), this species (UPDID096-17) is separate from P. amethysteum , from which it differs by the colour of the colony, lobed cloaca and the position of the lateral thoracic organ. Lotufo (2002) reported orange specimens from Rio de Janeiro and Espírito Santo, but we were able to examine the sample from Angra dos Reis and concluded that Lotufo’s sample (ColBio Tun 1245) actually belongs to the genus Leptoclinides Bjerkan, 1905 .

This species differs from P. cabofriense sp. nov., by the colour of the colony, the abundance, shape and position of the spicules, and in having more follicles and coils of the sperm duct. Given the single colony found and lack of larvae we prefer not to name it, although characters suggest that it is an undescribed species.

Distribution

Brazil: Rio de Janeiro (this study).

Figures

Fig. 12. Polysyncraton sp. a. Preserved colony. b. Thorax. c. Abdomen. Scale bars: a = 1 cm; b–c = 0.1 mm.

Fig. 5. Maximum likelihood tree of species of Polysyncraton based on analysis of 16 sequences of mitochondrial COI. Numbers on or below branches represent the support value of the bootstrap for Maximum likelihood (> 70%) and posterior Bayesian probabilities (> 0.97). Abbreviations of Brazilian states are explained in Table 1.