Trigonostomum Schmidt, 1852

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 : 662

Trigonostomum Schmidt, 1852

Trigonostomum armatum ( Jensen, 1878) Gamble, 1900 ( Fig. 17 )

Trigonostomum sp. 1 in Diez et al. (2023)

Known distribution. Norway ( Graff, 1882; Jensen, 1878; Westblad, 1954; Willems et al., 2004b), English Channel ( Gamble, 1893), North Sea ( Attems, 1897; Meixner, 1924, 1925), Ireland ( Gamble, 1893, 1900; Southern, 1912, 1915, 1936), Faeroe Islands ( Steinböck, 1931), Iceland ( Steinböck, 1938), Baltic Sea ( Ax, 1952). United Kingdom, Sweden, Wimeroux ( France), Curaçao, New South Wales, Arrawarra ( Australia), Nouméa ( New Caledonia), and South Georgia ( Willems et al., 2004b).

Material and distribution. Cuba: Observations on live animals. Nine whole mounts and one specimen for molecular analyses from Siboney (22 March and 5 June 2017) (HU XIX.4.25– XIX.4.33); sublittoral, on algae ( Ulva lactuca , U. flexuosa , and Gracilaria sp. ), 0.5 m deep, salinity 32–35‰. One whole mount from Bueycabón (6 February 2018) ( XIX.4.34), sublittoral, 0.5 m deep, on the red alga Galaxaura rugosa , salinity 33‰. One whole mount from Playa Caletón (24 January 2020) ( XIX.4.35), sublittoral, 0.5 m deep, on leaves of the seagrass Syringodium filiforme , salinity 37‰.

Remarks. For a detailed treatment of this species, see Willems et al. (2004b) and references therein. The live specimens collected in Cuba are about 0.8–1 mm long. The body is translucent, with anterior spots consisting of dark pigment granules. Each eye ( Fig. 17a : e) is observed as two pigmented spots due to squeezing. The stylet ( Fig. 17a, b : st, 17c) is 333–369 µm long (x = 352 µm; n = 8). The bursal appendage ( Fig. 17a, b : ba) is 84–100 µm long (x = 89 µm; n = 6). The bursal channel is sclerotised ( Fig. 17a, b : sbc).

Figures

Fig. 17 Trigonostomum arma- tum (Jensen, 1878) Gamble, 1900. a Body organisation (live animal). b Atrial organs. c Sty- let. b, c From a whole mount. a Structures oriented with the anterior end toward the left side of the plate. b–c Structures oriented with the anterior end toward the top of the plate