Reinhardorhynchus riegeri ( Karling, 1978 ) Diez & Monnens & Aguirre & Yurduseven & Jouk & Van Steenkiste & Leander & Schockaert & Reygel & Smeets & Artois, 2021

Diez, Yander L., Monnens, Marlies, Aguirre, Rosa Isabel, Yurduseven, Rana, Jouk, Philippe, Van Steenkiste, Niels W. L., Leander, Brian S., Schockaert, Ernest, Reygel, Patrick, Smeets, Karen & Artois, Tom, 2021, Taxonomy and phylogeny of Koinocystididae (Platyhelminthes, Kalyptorhynchia) with the description of three new genera and twelve new species, Zootaxa 4948 (4), pp. 451-500 : 462

Reinhardorhynchus riegeri ( Karling, 1978) comb. n.

( Fig. 4 )

Known distribution. Tuckers Town Cove (Type Locality) and Mullet Bay, Rock Hill, Bermuda ( Karling 1978) .

New records and material. Observations on live specimens. Seven whole mounts (HU XIII.3.08– XIII.3.14) and five serially-sectioned specimens (HU XIII.3.15– XIII.3.19) from Guardalavaca (21°07’32”N; 75°49’39”W), Banes, Holguín, Cuba (February 28, 2017), sandy bottoms and fine-grained sand, in beds of Syringodium filiforme , intertidal up to 0.2 m deep, salinity 35 ‰.

Description. Habitus and general organisation of the newly-collected specimens as described by Karling (1978). Specimens unpigmented, 1.4–2 mm long (x̄ = 1.8 mm; n = 6), with a pair eyes. The syncytial epidermis is 4 μm thick, fully ciliated. Cilia about 4 μm long. It includes two types of vacuoles: translucent empty ones and oth- ers filled with dark granules. Rhabdites present all over the epidermis, 1–2 μm long, some located at the epidermis’ surface, others deeply embedded within the epidermis.

The proboscis represents about 10% of the body length in live specimens. It has the typical koinocystidid morphology (see Brunet 1972; Karling 1980), with a strong juncture sphincter and does not differ from that of other species of Reinhardorhynchus gen. n. (see the description of the proboscis of R. riae sp. n. below). Only two pairs of integument retractors were observed: a ventral and a dorsal one. The exact number of fixators, dilatators and proboscis retractors could not be determined. The proboscis pore is closed by a sphincter.

The pharynx is located at 30%; its general morphology is as described for R. riae sp. n. (see below). However, a sphincter around the mouth was not observed. Three types of glands open in the distal part of the pharynx lumen: two eosinophilic ones (coarse-grained and medium-coarse grained, respectively) and a coarse-grained basophilic one.

The two testes are located at both the sides of the pharynx. Each of them is connected to a seminal vesicle by a vas deferens. The seminal vesicles fuse proximally from the copulatory bulb, forming a short seminal duct. The copulatory bulb encompasses the prostate vesicle, two spiny cirri, and two distal hooks. The ejaculatory cirrus (terminology of Karling 1978) ( Fig. 4A : ci, 4B) is 50–77 μm long (x̄ = 64 μm; n = 4). It is armed with numerous small spines of ± 7 μm long at one side and a group of larger spines 6–17 μm long (x̄ = 10 μm; n = 5) at the other. The papillary cirrus (terminology of Karling 1978) ( Fig. 4A : pc, 4C) is 110–129 μm long (x̄ = 117 μm; n = 7). Its proximal half is provided with ±2-μm-long triangular spines ( Fig. 4C : sp1), which in the distal half are 5–8 μm long (x̄ = 7 μm; n = 13) ( Fig. 4C : sp2). The two larger, strongly sclerotised hooks, which are attached to the wall of the male duct, differ from each other in size. The larger hook ( Fig. 4A : h1, 4D) is located next to the papillary cirrus and is 99–120 μm long (x̄ = 107 μm; n = 7). Its proximal base is extremely asymmetrical. The smaller one ( Fig. 4A : h2; 4E) has a less pronounced asymmetrical base. It is positioned near the proximal end of the ejaculatory cirrus and measures 40–63 μm (x̄ = 56 μm; n = 5).

Two elongated ovaries are situated rostral to the copulatory bulb. The oocytes are arranged in a row, increasing in diameter from the most proximal to the most distal one. The female duct receives the pair of oviducts proximally and opens into a distally located bursa through a strong sphincter. Embryos (4–5) without a surrounding shell were observed in some specimens, suggesting the species is (ovo-) viviparous.

Figures

FIGURE 4. Reinhardorhynchus riegeri (Karling, 1978) comb. n. A, sclerotised structures of the copulatory bulb. B, ejaculatory cirrus. C, papillary cirrus. D, larger hook. E, smaller hook. All with proximal end toward top of figure.