Promesostoma toryne, Diez & Monnens & Wuyts & Brendonck & Reygel & Schmidt-Rhaesa & Artois, 2023

Diez, Yander L., Monnens, Marlies, Wuyts, Arlien, Brendonck, Luc, Reygel, Patrick, Schmidt-Rhaesa, Andreas & Artois, Tom, 2023, Taxonomy and phylogeny of Dalytyphloplanida Willems et al., 2006 (Platyhelminthes: Rhabdocoela), with the description of a new family, a new genus, and sixteen new species from Cuba and Panama, Organisms Diversity & Evolution (New York, N. Y.) 23 (4), pp. 631-681 : 660-661

Promesostoma toryne sp. n. Artois & Diez

( Figs. 14d, e and 15f)

urn:lsid:zoobank.org:act:

Material and distribution. Panama: One specimen studied alive and whole mounted, designated holotype ( ZMH, No. V13691 ), collected in Las Perlas (type locality), Archipelago Las Perlas, Pacific side of Panama ( December 6, 2011); coarse sand with shell gravel and sponge spicules, 20 m deep, salinity 30 ‰.

Etymology. The name refers to the fact that one of the distal parts of the stylet is spoon shaped. Gr.: spoon.

Diagnosis. Species of Promesostoma without eyes. Copulatory bursa present. Seminal vesicle and prostate vesicle located beside the pharynx; male atrium with stylet caudal to the pharynx. Seminal vesicle and prostate vesicle open separately into the copulatory bulb. Stylet 109 µm long, distally split into two branches. Larger branch distally widened (16 µm wide) and spoon shaped, with a very broad distal aperture. Second branch 52 µm long and 7 µm wide.

Description. The overall organisation is comparable to that of other species of the genus Promesostoma (see Luther, 1943; Ax, 1951, 1952; Karling, 1967). The live animal is about 1 mm long, translucent, without eyes. Adenal rhabdite tracts present anteriorly. The pharynx ( Fig. 14d: ph) is 74 µm in diameter in the whole mount, located at 50%.

The testes are located anterior to the pharynx. The vasa deferentia open into a single seminal vesicle ( Fig. 14d: sv), located beside the pharynx. It was not clear from the whole mounted specimen whether or not the seminal vesicle is surrounded by a muscle layer. The prostate vesicle ( Fig. 14d: pv) is located beside the pharynx and next to the seminal vesicle. Both the seminal vesicle and prostate vesicle open separately into the male atrium. The male atrium also receives the male copulatory bursa ( Fig. 14d: mb; terminology of Karling, 1967). The stylet ( Figs. 14d and 15f: st, 14e) is 109 µm long and distally split in two branches. The larger branch ( Figs. 14e and 15f: p1) is distally widened (16 µm wide) and spoon shaped, with a very broad distal aperture. The second blanch ( Figs. 14e and 15f: p2) is 52 µm long and 7 µm wide.

The paired vitellaria ( Fig. 14d: vi) extend laterally, from the brain to the caudal body end. The globular to kidney-shaped ovaries ( Fig. 14d: ov) are located beside the stylet.

Trigonostomidae Graff, 1905

Ceratopera Hartog, 1964

Ceratopera paragracilis Ehlers & Ax, 1974

( Fig. 16)

Ceratopera sp. in Diez et al. (2023)

Known distribution. Isabela, Archipelago Colon, Galapagos Islands ( Ehlers & Ax, 1974). St. George’s West, Biological Station landing, Bermuda Islands, Bermuda ( Karling, 1978). Material and distribution. Cuba: Observations on live animals. Two whole mounts from Bahía Larga ( April 5, 2017) (HU XIX.4.22–XIX.4.23); on leaves of the seagrass T. testudinum , 1 m deep, salinity 34‰. One whole mount from Bueycabón ( 21 February 2018) (HU XIX.4.24), on leaves of T. testudinum and S. filiforme , 0.5 m deep, salinity 33‰. One specimen used for molecular analyses collected in Sardinero ( 18 March 2021); sublittoral, on leaves of T. testudinum , 0.6 m deep, salinity 34‰.

Remarks. The habitus and overall internal organisation of the specimens from Cuba correspond to the description of Ehlers and Ax (1974). Specimens are about 1 mm long, unpigmented and have a pair of eyes ( Fig. 16a: e). Large adenal rhabdite tracts are present anteriorly ( Fig. 16a: ar), with the cell bodies caudal to the eyes, their necks in between the eyes and opening terminally at the anterior end of the body. The stylet ( Fig. 16c, g: st, 16d) is 44–58 µm long ( x = 51 µm; n = 3), and 3–4 µm wide in the middle ( x = 4 µm; n = 3). The mantle ( Fig. 16c, g: ma, 16e) is 53 µm long ( n = 3). The bursal appendage ( Fig. 16 a: ba; b; f) is 60–64 µm long in the specimens from Bahía Larga ( x = 62 µm; n = 2) and 105 µm long in the specimen from Bueycabón, 14–16 µm wide medially ( x = 15 µm; n = 3), and 5 µm wide in the distal tubular part ( n = 2). In the specimen from Bueycabón, two distal tubes were observed, which are 31 µm long and 2 µm wide.