Pyura discrepans ( Sluiter, 1898 )

Monniot, Françoise, 2018, Ascidians collected during the Madibenthos expedition in Martinique 3. Stolidobranchia, Pyuridae and Molgulidae, Zootaxa 4459 (3), pp. 401-430 : 410-413

Pyura discrepans ( Sluiter, 1898)

Figs 10 , 11

Cynthia discrepans Sluiter, 1898 , Jamaïca

Pyura discrepans: Monniot C. 1983 (holotype redescription)

Station: AB 159 (MNHN S2 PYU 500, slide 771)

The single specimen 23mm in diameter has a hard brown tunic with a corrugated surface ( Fig. 10A ). The siphons are not protruding, spaced at 1/3 of the body length. No siphonal spinules have been seen, either around the siphons openings or on the brown internal lining of the siphons. The body wall was red but turned yellow in formalin ( Fig. 10B ). The musculature is composed of strong siphon sphincters and regularly crossed fibres on the body. Both siphons have a thin velum. There are 18 oral tentacles with ramifications of a single order: some smaller ones are intercalated. The dorsal tubercle opens anteriorly in a C in a wide V of the prepharyngeal band. The dorsal lamina ( Fig. 10C ) is a flat band of tissue with the rim erect in well separated languets. The branchial sac ( Fig. 11B ) has 6 folds on each side with the formula for the right side: E- (15) 5 (17) 6 (22) 6 (22) 7 (20) 4 (22) 3- DL.

The stigmata are very irregular in shape and distribution: they are oval or round holes often in incomplete rows. The transverse vessels are also irregular. This branchial structure seems to be a characteristic of the species as it corresponds to Sluiter’s description and also to Monniot’s (1983) observations.

The digestive tract ( Fig. 11A ) occupies the posterior half of the left body side, and forms a wide opened loop. The intestine is narrow and isodiametric. The anus has a smooth rim. The stomach is elongated covered by several papillated hepatic lobes ( Fig. 11A ). There are no endocarps on the gut. There is one gonad on each side made of well separated lobes whose ducts reach a longitudinal gonoduct ending in a long papilla near the atrial opening ( Fig. 11A ).

Foliated endocarps are numerous on the body wall and are also present on the gonad lobes ( Fig. 11A ).

Pyura discrepans is recorded here for only the second time.

Figures

FIGURE 10. Pyura discrepans. A, specimen with tunic; B, specimen without tunic; C, detail of the dorsal lamina (stained). Scale bars A,B = 1cm.

FIGURE 11. Pyura discrepans (stained). A, dissection, scale bar = 1cm; B, branchial sac.