Pyura vittata Van

Monniot, Françoise, 2018, Ascidians collected during the Madibenthos expedition in Martinique 3. Stolidobranchia, Pyuridae and Molgulidae, Zootaxa 4459 (3), pp. 401-430 : 423

Pyura vittata Van name, 1921

Figs 21 , 22 , 23

Van Name 1921, and synonymy; Monniot C. 1983: Martinique; Rocha et al 2012b, Brazil.

Not Monniot F. 2016a = P.vannamei

Stations: AB 102, 126, 157, 159, 175. AR 101, 110, 116, 158, 164, 189, 456, 465. (MNHN S2 PYU 505)

The numerous specimens collected in Martinique are all covered with epibionts obscuring the red-brown tunic ( Fig. 21B ). From 2 to 6cm in length they were fixed by the ventral side and have the siphons widely separated. The tunic is wrinkled with papillae at the siphons wearing long iridescent spinules. The largest spinules reach 0.32mm in length and are inflated centrally in a more or less wide disk ( Fig. 23 ). The internal tunic of the siphons is brown and thick with spinules anteriorly prolonged by a thin membrane down to the tentacles. Extracted from the tunic the siphon wall is red and the body yellow. The musculature is made of strong siphon sphincters and of crossed fibres in separated ribbons on the body sides ( Figs 21A ; 22A ). The oral tentacles in 3 orders of size have a wide base pinnules but thin branching and are inserted at the base of a thin but large velum. The prepharyngeal band has two crests and is deeply indented dorsally. The dorsal tubercle opens anteriorly its horns variably curled ( Fig. 22A ). The branchial tissue has a pink-red colour fading in formalin. The dorsal lamina is made of dense long papillae ( Fig. 22B ). There are 6 high branchial folds per side well separated ( Fig. 22B ). The formula on the right side in a specimen 3.5cm large is: E-8 (14) 9 (20) 10 (20) 10 (20) 8 (20) 7 (14) 6-DL.

The stigmata do not coil at the top of the infundibula. Parastigmatic vessels are present. The longitudinal vessels end in long papillae. The digestive tract extends far anteriorly in a long loop ( Figs 21A ; 22A ). The digestive gland has digitiform papillae on the cardia and a large dark brown branched mass in shape of cauliflower ( Figs 21A ; 22A .). The ascending limb of the intestine is narrow but the rectum is enlarged into a pouch ( Figs 21A ; 22A ) and bent in a secondary loop. The anus has a few round lobes often turned outward. Numerous foliated endocarps line the intestine and become larger on the dorsal side of the gut ( Figs 21A ; 22A ). The left gonad is long, curved and occupies the whole gut loop. The right gonad is long with up to 40 lobes close to each other, in a double series on each side of the common gonoduct each ending in a short papilla near the atrial siphon opening. There are endocarps on the gonad lobes particularly developed on the dorsal anterior side of the right gonad ( Figs. 21A 22A ). There are no endocarps on the body wall. The right gonad is parallel to the endostyle but separated from it by a long and wide blood vessel ( Figs 21C ; 22A ). There is a velum at the atrial siphon.

The long spinules have a lanceolated shape, the central part usually very inflated appearing at lower magnification as shining plates. The tip is sharp and the base forms a small bulb ( Fig.23 ); there are mixed sizes with the largest about 0.32mm long, and with varied width.

P. vittata differs from other West Atlantic Pyura with 6 branchial folds by the combination of an enlarged rectum, the absence of endocarps on the body wall, gonads long and curved with very numerous lobes, the presence of long iridescent siphonal spinules on the tunic and a constant cover of epibionts on the body. This species was often been considered variable ( Van Name 1902; Van Name 1945, Monniot 1983) and confused with other Pyura with 6 branchial folds; many records in the literature are not precise enough to ascertain the worldwide distribution given for this species.

Figures

FIGURE 21. Pyura vittata. A, dissection; B, one specimen; C, gonad lobes and heart vessel. Scale bars A,B =1cm.

FIGURE 22. Pyura vittata (stained). A, dissection; B, branchial sac. Scale bars = 1cm.

FIGURE 23. Pyura vittata spinules of 2 specimens. Scale bars = 0.1mm.