Trigonostomum yoandrisi, 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 : 663-664

Trigonostomum yoandrisi sp. n. Diez, Reygel & Artois ( Fig. 20 )

urn:lsid:zoobank.org:act:5950B008-9B1F-4F5E-96FE-7467E881C6CD

Trigonostomum sp. 4 in Diez et al. (2023)

Material and distribution. Cuba: Observations on live animals, whole mounted afterwards. Two whole mounts from Siboney (Type locality) (December 6, 2017), one of which is designated holotype ( ZMH, No. V13692 ) and the other paratype (HU, No. V885 ); sublittoral, on the alga Dictyota sp. , 4 m deep, salinity 33 ‰.

Etymology. Species named after Prof. Dr Yoandri Suárez Megna (Universidad de Oriente, Cuba), specialist in freshwater beetles.

Diagnosis. Species of Trigonostomum with a copulatory organ which consist of a stylet and two mantle plates. Funnel-shaped stylet ~ 24 μm long. One mantle plate is ~ 28 µm long and 17–18 µm wide proximally, tapering to a distal sharp tip. Second plate X shaped, ~ 21 µm long and 17–18 µm wide proximally; distally, it forms two sharp hooks, ~ 12 µm long. Bursal appendage 19–20 µm long as a whole, distally branching in two coiled tubes~ 48 µm long and ~ 3 µm in diameter.

Description. The animals are 0.47–0.51 mm long (x = 0.49 mm; n =2), measured on the whole mounts, translucent, with a pair of eyes ( Fig. 20a, b : e). The pharynx ( Fig. 20a, b : ph) is 74–80 µm long (x = 77 µm; n = 2), as measured on whole mounts, and located in the first body half.

The paired testes ( Fig. 20a : t) are located at the body’s midpoint. The atrial organs are located in the second body half. The vasa deferentia form seminal vesicles that open into the copulatory bulb. The copulatory bulb encloses the prostate vesicle and copulatory organ. The sclerotised parts of the copulatory organ consist of the stylet proper and two mantle pieces. The funnel-shaped stylet ( Fig. 20a, d–f : st) is 22–25 µm long (x = 24 µm; n = 2) and 11–12 µm wide proximally. It tapers to a blunt distal tip. One plate of the mantle ( Fig. 20d–f : pl1) is 26–29 µm long (x = 28 µm; n = 2) and 17–18 µm wide proximally; distally, it forms a triangular tip. The second plate of the mantle ( Fig. 20d–f : pl2) is X shaped, 18–24 µm long (x = 21 µm; n = 2) and 17–18 µm wide proximally. Distally, it displays two triangular projections, 9–15 µm long (x = 12 µm; n = 4) which end in a pointed tip.

The paired vitellaria extend laterally between the pharynx and copulatory bulb. The bursal appendage ( Fig. 20a; c : ba; g) is 19–20 µm long (n = 2), and consists of a proximal case and two distal, coiled tubes (~ 360°), measuring 46–49 µm (x = 48 µm; n = 2) in length and ~ 3 µm in diameter.

Figures

Fig. 20 Trigonostomum yoan- drisi sp. n. a Body organisation (live animal). b Anterior body end. c, g Bursal appendage. d–f Copulatory organ. b–e, g From the holotype. a, g Structures oriented with the anterior end toward the right side of the plate. b–d Structures oriented with the anterior end toward the left side of the plate. e–f Struc- tures oriented with the anterior end toward the top of the plate