Reinhardorhynchus unicornis Diez, Aguirre, Reygel & Artois sp. n.

(Fig. 16)

urn:lsid:zoobank.org:act: B5662028-C218-43A0-9A93-7B2557629C76

Material and distribution. One specimen studied alive, whole mounted afterwards, designated holotype (FMNH https://id.luomus.fi/ KV.653), collected in Guardalavaca (21°07’32”N; 75°49’39”W) (Type Locality), Banes, Holguín, Cuba (February 28, 2017), fine-grained sand in a bed of Syringodium filiforme, 0.2 m deep, salinity 35 ‰.

Etymology. The epithet refers to the copulatory organ, which is armed with a single accessory hook only.

Diagnosis. Species of Reinhardorhynchus gen. n. with a copulatory bulb encompassing an ejaculatory cirrus, a papillary cirrus, and an accessory hook. Ejaculatory cirrus 73 μm long, armed with 5-μm-long, triangular spines. Papillary cirrus 119 μm long, armed with triangular, ±1-μm-long spines which become longer distally, up to ±11 μm. Curved hook 100 μm long and 40 μm wide at its asymmetrical base.

Description. The specimen is 1.6 mm long, unpigmented, with a pair of eyes. The proboscis is about 20% of the body length in the live specimen. As far as could be seen on the live specimen, it shows the distinctive features of the typical koinocystidid proboscis (see Brunet 1972; Karling 1980), with a strong juncture sphincter. The pharynx (Fig. 16B: ph) has a diameter of 15% of the body length in live specimens, and is located at 40%.

A pair of testes is located rostrally from the pharynx. The seminal vesicles (Fig. 16A–B & 16E: sv) fuse just before entering the copulatory bulb and form a short ejaculatory duct (Fig. 16A: ed). The extracapsular prostate glands (Fig. 16A: pg) open proximally into the copulatory bulb. The copulatory bulb (Fig. 16A) encompasses the prostate vesicle (Fig. 16A–B: pv), an ejaculatory cirrus, a papillary cirrus, and one distal hook. Proximally, a bundle of prostate glands opens into the copulatory bulb. The ejaculatory cirrus (Fig. 16A–B & 16E–F: ci) is 73 μm long and armed with 4–7-μm-long triangular spines (x̄ = 5 μm; n = 12). The papillary cirrus (Fig. 16A–B & 16E–F: pc, 16D) is proximally enclosed in a globular papilla (Fig. 16A: pa). It is 119 μm long and 24 μm wide, and armed with triangular and ±1-μm-long spines; some spines are larger distally (±11 μm long). The caudally-located hook (Fig. 16A–B & 16E: h, 16C) is 100 μm long and 40 μm wide at its asymmetrical base.

The pair of ovoid ovaries is situated rostrally from the copulatory bulb, with the oocytes organised in a row. The vitellaria (Fig. 16B: vi) extend from beside the pharynx to the body end.