Typhlopolycystis tahitiensis, Schockaert & Moons & Janssen & Tessens & Reygel & Revis & Jouk & Willems & Artois, 2019

Schockaert, Ernest R., Moons, Patricia, Janssen, Toon, Tessens, Bart S., Reygel, Patrick C., Revis, Nathalie, Jouk, Philippe E. H., Willems, Wim R. & Artois, Tom J., 2019, On the genus Typhlopolycystis Karling, 1956 (Platyhelminthes, Kalyptorhynchia, Polycystididae), with data on the five known species and the description of eleven new species, Zootaxa 4603 (1), pp. 81-104 : 95-97

Typhlopolycystis tahitiensis n. sp. Schockaert, Jouk and Artois.

( Figs 12 D–G)

Diagnosis. Species of Typhlopolycystis of about 1–1.2 mm with a proboscis 1/6 to 1/5 of the body length and with eyes as far from each other as from the body rim. The prostate stylet about 14–16 µm broad, 78–91 µm long (n=6, 78 µm in the holotype), almost straight in the proximal 3/4 of its length, then bent over about 60° and tapering to a blunt end. The accessory stylet starts at the convex end of the main stylet; it is straight and pointed, 72–81 µm long (n=6, 72 µm in the holotype) and 7–9 µm thick. The whole stylet complex has a proximal diameter of 2 5–33 µm, including the “head” at the concave side. The prostate vesicle seems reduced. The seminal receptacle is pearshaped.

Occurrence. French Polynesia: Tahiti , Papehue public beach, fine sand mixed with some fine coral debris and a little silt 17°39'52.3"S 149°35'47.4"W (14 September 2017) (Type locality) ; Tahiti, Tamanu, beach at Le Méridien hotel, sand zone close to water edge, with periodically strong currents, fine sand with some silt, 20–50 cm deep 17°38'13.3"S 149°36'47.5"W (16 September, 3 and 10 October 2017) ; Rangiroa Atoll, Tiputa, beach in front of harbour, fine sand with some silt, 1.5 m deep 14°58'48.2"S 147°37'25.0"W (22 September 2017) ; Moorea, Maharepa, reef in lagoon, sandy area between coral heads, very fine sand, 1 m deep 17°28'44.5"S 149°47'49.2"W (02 September 2017)(all by Jouk) .

Material examined. Observations and micrographs of living animals; six whole mounts, four from Tahiti (one of which designated the holotype—SMNH nr 8960 and HU nrs III.1.48–50), three from Rangiroa (HU nrs III.2.01–03) and one from Moorea (UH nr III.2.04). Etymology. Species named after the type locality.

Additional remarks. This species is extremely similar to T. riegeri n. sp. and it is with some hesitation that we attribute these individuals to a new species. The hard parts of the copulatory organ are very much alike, though with some subtle differences: the prostate stylet of T. tahitiensis n. sp. is shorter than in T. riegeri n. sp. (84 against 101 µm means) and the terminal bend comes at 3/4 of the prostate stylet and over about 60°, while in T. riegeri n. sp. it comes at 2/3 and over about 90°. The accessory stylet of T. riegeri n. sp. is very narrow at its base where it makes a turn of nearly 180°; in T. tahitiensis n. sp. it is straight with the same width over its whole length. T. riegeri n. sp. seems to lack a prostate vesicle, but this should be confirmed on new material. Another reason to consider the species as separate is the distance between East Africa and Tahiti.

Figures

FIGURE 12. Typhlopolycystis riegeri n. sp. (A) The atrial organs in the living animal. (B) The copulatory organ in the holotype. (C) The copulatory organ in the paratype. Typhlopolycystis tahitiensis n.sp. (D) The copulatory organ in the holotype. (E-F) The copulatory organ in two syntypes from Tahiti (G). The copulatory organ in an individual from Rangiroa. (H) The atrial organs in the whole mount of a syntype. Typhlopolycystis australiensis n.sp. (I) The copulatory organ in the holotype and (J) its seminal receptacle. (scale = 20 µm)