Itaipusa novacaledonica Diez, Schockaert, Reygel & Artois 2021, sp. n.

Itaipusa novacaledonica Diez, Schockaert, Reygel & Artois sp. n.

(Fig. 3)

urn:lsid:zoobank.org:act: 9433D2B5-29ED-40E6-8DB3-7786947F4C94

Itaipusa n. sp. 2 in Tessens et al. (2014)

Material and distribution. Observations on live specimens. Two whole mounts, one of which is designated holotype (FMNH https://id.luomus.fi/ KV.647), the other in HU (XIII.3.07), and one serially-sectioned specimen (HU XIII.3.08), collected in Anse Vata Bay (22°18’19”S; 166°26’50”E) (Type Locality), Nouméa, New Caledonia (October 22, 2003), on algae (Ulva -like) and sediment taken from rocks in the mouth of a small river.

Etymology. Species named after New Caledonia, where the material was collected.

Diagnosis. Species of Itaipusa with a cirrus with two longitudinal rows of triangular spines. One row is inverted U-shaped and ±136 μm long, the other is M-shaped and ±193 μm long. Spines ±3 μm long in both rows, slightly larger at one of the ends (±5 μm long). Distally, the male duct opens in a penis papilla, that is partially sclerotised.

Description. The specimens are ± 1 mm long, translucent, with a pair of rounded eyes. Habitus and general morphology do not deviate from other species of Itaipusa described above. The proboscis is about 20% of the body length in the live specimens. Basophilic and eosinophilic glands open into the proboscis through its caudal wall. Two pairs of integument retractors were observed: a ventral and a dorsal one. Other muscles were not observed.

The morphology of the pharynx does not differ from that of I. divae. It is located at 40% and its diameter is 15% of the body length. Three types of glands open in the distal part of the pharynx lumen: two eosinophilic ones (filled with a coarse-grained or a fine-grained secretion), and basophilic glands with a coarse-grained secretion.

A pair of testes is located antero-lateral to the pharynx. Caudally from the pharynx the vasa deferentia form a pair of seminal vesicles. The seminal vesicles (Fig. 3A & 3C: sv) fuse to form the seminal duct just before entering the copulatory bulb. The seminal vesicles and seminal duct are lined by a nucleated epithelium and surrounded by an external longitudinal muscle layer. The atrial organs are located in the caudal body fourth. The copulatory bulb is 168–196 μm long (x̄ = 182 μm; n = 2) and surrounded by an external, longitudinal muscle layer and a thick, internal circular muscle layer. The seminal duct is situated in the proximal half of the copulatory bulb. Where the seminal duct opens into the cirrus, filiform prostate glands containing a coarse-grained eosinophilic secretion also enter the cirrus (Fig. 3A & 3C: pv). The armature of the cirrus (Fig. 3A–C: ci, 3D) consists of two longitudinal spiny rows: one row is M-shaped and 145–240 μm long (x̄ = 193 μm; n = 2) (Fig. 3B & 3D: spr1) and the other one is invert U-shaped and 134–138 μm long (x̄ = 136 μm; n = 2) (Fig. 3B & 3D: spr2). In both rows, the triangular spines are 2–4 μm long (x̄ = 3 μm; n = 2), reaching up to 5 µm at one of the ends. The rows of spines are conspicuous in the distal part of the cirrus, but less noticeable in the more proximal part. The copulatory bulb opens distally in a penis papilla (Fig. 3B: pp), which is partially sclerotised. A number of glands (Fig. 3B: gl) containing fine-grained eosinophilic secretion open distally into the penis papilla.

The elongated ovaries (Fig. 3A: ov) lie beside the copulatory bulb. The oviducts open into the sperm-containing female duct. The female duct (Fig. 3A: fd) opens into the female atrium through a strong sphincter (Fig. 3A: sph1). The walls of the female atrium (Fig. 3A: fa) are weakly muscular. The bursal stalk (Fig. 3A: bs) is tubular in one specimen and swollen in a second one. It is surrounded by two strong and folded muscle layer consisting of external circular and internal longitudinal muscles. It connects with the caudally-located bursa (Fig. 3A: b), which is lined by feeble circular muscles. The uterus (Fig. 3A: ut) is oriented forward and is surrounded by a sphincter more or less in its midpart (Fig. 3A: sph2).