Pyura lopezlegentilae, Rocha & Counts, 2019

Rocha, Rosana M. & Counts, Bailey Keegan, 2019, Pyura (Tunicata: Ascidiacea: Pyuridae) on the coasts of Panama, Zootaxa 4564 (2), pp. 491-513 : 502-505

Pyura lopezlegentilae sp. nov.

( Figures 9–11 )

urn:lsid:zoobank.org:act:006BDF9E-AC66-4805-BC18-49F0E1D21F6E

Material examined: Holotype: MZUSP556 Crawl Key , Bocas del Toro, 9°14'38”N 82°08'25”W, leg. R. M. Rocha, 25.08.2006

Paratypes: DZUP PYU-87 , Punta Caracol , Isla Colon , Bocas del Toro, 9°22’37.6”N 82°18’7”W, leg. R. Collin, 05.08.2003 ; DZUP PYU-88 , Solarte , Bocas del Toro, 9°17'30”N 82°10'20”W, leg. R. M. Rocha ,

11.08.2003; DZUP PYU-111 , Bastimentos , Bocas del Toro, 9°16'37”N 82°10'16”W, leg. R. M. Rocha , 04.08.2008; DZUP PYU-112 , STRI Bay , Bocas del Toro, 9°21'09”N 82°15'32”W, leg. R. M. Rocha , 27.08.2008, DZUP PYU- 113 , Big Bight , Bocas del Toro, 9°21'56”N, 82°16'49”W, leg. R. M. Rocha , 06.06.2009; DZUP PYU-114 , Garden Reef , Isla Solarte , Bocas del Toro, 9°19'23”N 82°13'11”W, leg. R. M. Rocha , 11.06.2009; DZUP PYU-115 , City Pilings , Bocas del Toro, 9°20'27”N 82°14'21”W , 19.08.2006; DZUP PYU-116 , Isla Solarte , Bocas del Toro, 9°17'55.74”N 82°11'40.32”W, leg. G. Lambert , 15.08.2006; DZUP PYU-117 , Isla Colon-Mangrove , Bocas del Toro, 9°21'41.9”N 82°16'28.9”W, leg. R. M. Rocha , 25.07.2008; DZUP PYU-118 , STRI Dock , Bocas del Toro, 9°21'41.9”N 82°16'28.9”W, leg. R. M. Rocha , 03.08.2006; DZUP PYU-119 , Isla Pastores , Bocas del Toro, 9°13'09”N 82°19'29”W, leg. R. M. Rocha , 14.06.2011; DZUP PYU-120 , Bastimentos , 9°16’31.8”N 82°10’16.9"W, leg. R. M. Rocha , 04.07.2011; DZUP PYU-121 , Isla Colon , Bocas del Toro, 9°21'45.95”N 82°16'30.01”W, leg. R. M. Rocha , 02.07.2011; DZUP PYU-122 , Punta Caracol , Bocas del Toro, 9°22'28”N 82°17'57”W, leg. R. M. Rocha , 24.06.2011; DZUP PYU-123 , Almirante Bay , Bastimentos , Bocas del Toro, 9°14'33.72”N 82°08'57.84”W, leg. R. M. Rocha , 28.06.2011; DZUP PYU-124 , Solarte , Bocas del Toro, 9°16'38.9”N 82°12'24.1”W, leg. R. M. Rocha , 19.06.2014; DZUP PYU-125 , Mangrove , Solarte , Bocas del Toro, 9°18'36.3”N 82°12'23.04”W, leg. R. M. Rocha , 10.06.2011.

Etymology. The name of the species is in homage to Susanna López-Legentil for her important research contributions on ascidian genetics and systematics.

Description. Living specimens inhabit piers, mangroves, and coral reefs. Animals are oval shaped and reach up to 4 cm. Fresh specimens frequently display red and yellow siphons; however, in some samples, the siphons show only red coloration ( Fig. 9 ). A distinctive membrane, resembling a flap and often yellow in color, is viewed through the atrial siphon and is part of the vellum that line that siphon ( Fig 9B, C ). Epibionts cover the outside of the tunic. After fixation, the tunic displays yellow and brown and is 1–3 mm thick. The inside of the tunic is white. The holotype is 2.2 cm in height and 3.0 cm wide; brown in color when preserved. The siphons are extremely contracted from fixation. The tunic is rough with bumps densely concentrated around the siphons. Without the tunic, the holotype is 1.3 cm in height and 2.1 cm wide, discounting the siphons. Both the oral and atrial siphons are 4 mm long. The continuation of the tunic inside the siphons form an iridescent vellum, containing many short and parrot-beak-shaped spines (40–50 µm) with a red spot in each ( Fig. 10C ).

The body wall has no coloration; however, when fresh, the siphons are red. The red coloration dissipates the longer the length of fixation. A small round projection of the body wall is always viewed at the base of the

oral siphon, on the ventral margin at the level of the anterior end of the endostyle ( Fig. 10A ). Dense circular muscles surround the siphons and extend a slight distance onto the body wall. Longitudinal muscles form muscle bands that radiate from the base of the siphons slowly disbanding toward the gonadal and intestinal region. The gonadal and intestinal region is transparent and the large, spherical gonad lobes are easily seen through the body wall ( Figs 10A, B, D ).

The holotype contains 29 laterally flattened tentacles with three orders of sizes, the largest 3–4 mm long. The number of tentacles ranges from 29 to 40. Several specimens show a higher degree of ramification than others. There is little separation between the tentacles and the prepharyngeal groove; which is made up of two equal sized membranes. The shape of the dorsal tubercle varies among samples. In the holotype, the dorsal tubercle is a thick U-shape situated in a deep V constructed by the prepharyngeal groove. The ends can be coiled. In one sample, the dorsal tubercle was offset to the right of the neural ganglion and significantly smaller than the other samples ( Fig 11B, C ). The dorsal lamina begins a few millimeters posterior to the V-shaped peritubercle region. Long languets are densely placed down the entire length of the dorsal lamina; 150 in the holotype.

The pharynx is uncolored with six high folds per side. Folds commonly being higher the closer to the dorsal lamina. Overlap of folds occurs; more prevalent on the left side ( Fig. 11A ). The holotype has a total of 369 longitudinal vessels; number of vessels range from 335 to 369.

The longitudinal vessel formula of the holotype is (from right to left):

E 4 (20) 4 (24) 6 (29) 3 (30) 4 (30) 2 (28) 4 DL 2 (29) 2 (27) 2 (29) 3 (30) 3 (30) 3 (20) 1 E

Longitudinal vessels fray toward the base of the animal, making languets around the esophageal opening. Parastigmatic vessels are present and the number of stigmata range from five to six per mesh.

Endocarps line the descending limb of the intestine; attached partially to the body wall and partially to the intestine. The endocarps are not fleshy, instead, they resemble parallel extensions of the intestine. They are not present in any other region of the body wall, neither on the gonadal lobes.

The alimentary canal occupies the entire left side of the animal ( Fig. 11D ). The digestive gland is large, occupying a majority of the ascending limb of the intestine. The isodiametric intestine primary loop is close to the prepharyngeal groove. The anus is lobed and lies at the base atrial siphon ( Fig. 11F ). There is a thick membrane around the atrial siphon that always form four long projections, two of them anterior and two posterior. This membrane appears to have two different layers: an iridescent tissue that lies on a thicker tissue that makes up most of the membrane. The iridescent tissue does not have spinules and it is not present in some samples, likely due to the long length of fixation. In one sample, the flap also contained numerous calcareous spicules in the upper layer. Calcareous spicules in the shape of antlers were also seen on the wall of blood vessels and intestine of some specimens ( Fig 11E ).

Gonad lobes are large and spherical; decreasing in size posteriorly. The number of lobes ranges from 12 to 22 on the left side. The right side of the animal is almost completely occupied by the large right gonad with 12 to 20 lobes ( Fig. 11d ). Gonoducts are long and open at the same level of the anus ( Fig. 11F ).

Remarks. In the field, Pyura lopezlegentilae can be confused with P. longispina due to the same size, round shape and red coloration of the siphons. However, no other Pyura species is known to have the conspicuous yellow flap that is visible through the atrial siphon of P. lopezlegentilae , and the internal view of the atrial velum show that its margin is indeed large and form long projections. Further, living P. longispina usually have a wider oral siphon than P. lopezlegentilae . Internally, the structure of the gonads is very different as well as the size and shape of spinules. Pyura lopezlegentilae has also the gut shape, gonad shape and presence of calcareous spicules in common with P. munita but P. munita is usually smaller (max diameter 3 cm), covered by sand, has fewer longitudinal vessels (216–265) and does not have endocarps ( Monniot 1972, 1983). Monniot (1972) mentioned a divided atrial vellum but did not comment anything special about it and the atrial vellum of P. lopezlegentilae is a very regular and noticeable structure. We studied two individuals collected in Belize and identified by I. Goodbody as P. munita (USNM 1092832 and USNM 17600). They were smaller animals and the vellum covering the siphons were iridescent but when observed under the compound microscope no spinules were found, but instead, we observed a layer of regular structures like small tiles ( Fig. 12 ). Thus we believe that P. lopezlegentilae and P. munita are two different species.

Figures

FIGURE 9. Pyura lopezlegentilae sp. nov. A–D. Animals in the field. In B and C it is possible to see the yellow flap formed by the atrial siphon vellum.

FIGURE 10. Pyura lopezlegentilae sp. nov. A. Left side of the animal without the tunic. B. Right side of the animal without the tunic. C. Siphonal spinules. D. Detail of body wall musculature over the left gonad. Scale bars A = 1 cm, C = 50 µm.

FIGURE 11. Pyura lopezlegentilae sp. nov. A. Dissected view of the animal with the pharynx. B. Oral tentacles (stained). C. Anterior region with oral tentacles and dorsal tubercle (stained). D. Dissected view of the animal without the pharynx, showing the reproductive and digestive systems. E. Close up view of a blood vessel with antler-like spicules. F. Atrial siphon, anus and gonoduct.

FIGURE 12. Pyura munita (Van Name, 1902), USNM 1092832. A. Dissected anterior region showing iridescent vellum (arrows). B. microscopic view of vellum showing tile-like scales.