Reinhardorhynchus hexacornutus Jouk, Diez, Reygel & 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 : 473-476

Reinhardorhynchus hexacornutus Jouk, Diez, Reygel & Artois sp. n.

( Fig. 11 )

urn:lsid:zoobank.org:act:45A01032-0A38-4976-9AF0-B2C6F277FC55

Material and distribution. Observations on live specimens, whole mounted afterwards. Five whole mounts, one

of which is designated holotype ( FMNH https://id.luomus.fi/ KV.650), the others in HU ( XIII.4.16– XIII.4.19), collected in Puna’auia (17°36’42”S; 149°36’51”W) (Type Locality), Pape’ete , Tahiti, Society Islands, French Polynesia (March 18, 2016), sediment with ripple marks, 50 cm deep, fine black sand .

Etymology. Species named after the presence of six hooks within the copulatory bulb.

Diagnosis. Species of Reinhardorhynchus gen. n. with the copulatory bulb encompassing the ejaculatory duct, a papillary cirrus, and six hooks. Ejaculatory duct runs through the copulatory bulb and opens distally into the male atrium. Papillary cirrus ±84 μm long, armed with nail-shaped spines, ±2 μm long proximally and ±1.2 μm distally. Hooks funnel-shaped, curved, and ending in a sharp tip, each of different size, ranging from 11μm long and 5 μm wide to 54 µm long and 23 µm wide.

Description. The specimens are 0.9–1.3 mm long (x̄ = 1.1 mm; n = 3), translucent, with a pair of eyes ( Fig. 11A : e). The proboscis ( Fig. 11A : pr) is of the typical koinocystidid construction (see Brunet 1972; Karling 1980), with a strong juncture sphincter. The pharynx ( Fig. 11A : ph) has a diameter of 10% of the body length in live specimens, and is located at 30%.

Two testes ( Fig. 11A : t) are positioned behind the pharynx. The vasa deferentia form the seminal vesicles ( Fig. 11A–B : sv), which fuse to form a short seminal duct just before entering the copulatory bulb. The oval copulatory bulb is 125 μm long (n = 1) and encompasses the ejaculatory duct, a papillary cirrus, and six accessory hooks. The ejaculatory duct ( Fig. 11B & 11J : ed) runs through the proximal part of the copulatory bulb and opens distally into the male atrium. The spiny part of the papillary cirrus ( Fig. 11A–C & 11J–H : pc) is 73–91 μm long (x̄ = 84 μm; n = 4) and armed with nail-shaped spines. Proximally, these spines are 1.2–2.4 μm long (x̄ = 2 μm; n = 20) and dis- tally they decrease in size to ±1.2 μm (n = 15). Proximally, the papillary cirrus is enclosed in a papilla ( Fig. 11A–C & 11J–K : pa), with a glandular organ opening into the cirrus. The accessory hooks ( Fig. 11A : h, 11B & 11J–K: h1–h6, 11D–I) are funnel-shaped, curved, and ending in a sharp tip. They differ in size, ranging from 11 µm long and 5 µm wide at the base for the smallest one to 54 μm long and 23 µm wide for the largest one. The hooks are organised in two groups; one group is formed by hooks 1–4 ( Fig. 11I, 11G, 11D & 11H , respectively) and the other group includes hooks 5–6 ( Fig. 11F & 11E , respectively). The hooks 1–4 are located in a well-developed muscular sac.

The vitellaria ( Fig. 11A : vi) extend along both sides of the body from the level of the pharynx to the copulatory organs. A pair of ovaries ( Fig. 11A : ov) is located at the midbody, rostral to the copulatory bulb. The oocytes are organised in a row. The oviducts open into the proximal end of the female duct. The female duct ( Fig. 11A : fd) opens into the female atrium through a strong sphincter. The muscular bursal stalk ( Fig. 11A : bs) connects the caudallylocated bursa ( Fig. 11A : b) to the female atrium. The common gonopore ( Fig. 11A : cg) opens at 80%.

Figures

FIGURE 11. Reinhardorhynchus hexacornutus sp. n.. A, general organisation (from a live animal). B & J–K, copulatory bulb. C, cirrus. D–I: hooks. A–B, from live animals. C–J, from the holotype. K, from a reference specimen (HU XIII.4.16). All oriented with proximal end toward top of figure.