Reinhardorhynchus sagamianus Tsuyuki, Reyes, Oya, & Van Steenkiste, 2024

Tsuyuki, Aoi, Reyes, Jhoe, Oya, Yuki, Wakeman, Kevin C., Leander, Brian S. & Van Steenkiste, Niels W. L., 2024, Marine microturbellarians from Japan, with descriptions of two new species of Reinhardorhynchus (Platyhelminthes, Rhabdocoela, Koinocystididae), Zoosystematics and Evolution 100 (3), pp. 877-895 : 877-895

publication ID	https://doi.org/ 10.3897/zse.100.120244
publication LSID	lsid:zoobank.org:pub:C025A8A6-116F-4BAF-94AA-6276BC84D2C8
DOI	https://doi.org/10.5281/zenodo.12636675
persistent identifier	https://treatment.plazi.org/id/B2534AFD-3461-4329-A62F-3C6AC8467FB2
taxon LSID	lsid:zoobank.org:act:B2534AFD-3461-4329-A62F-3C6AC8467FB2
treatment provided by	Zoosystematics and Evolution by Pensoft
scientific name	Reinhardorhynchus sagamianus Tsuyuki, Reyes, Oya, & Van Steenkiste
status	sp. nov.

Treatment

Reinhardorhynchus sagamianus Tsuyuki, Reyes, Oya, & Van Steenkiste sp. nov.

Fig. 3 View Figure 3

Material examined.

Holotype: Japan • 1; Kanagawa Prefecture, Hayama, Sangashita beach ; (35 ° 15 ' 58.3 " N, 139 ° 34 ' 19.6 " E); 21 April 2023; sandy substrates; Aoi Tsuyuki and Yuki Oya leg.; one individual worm in a single slide; [Holotype: NSMT - Pl 6460 ]. GoogleMaps

Paratype: Japan • 1; locality same as for holotype; 30 Aug 2023; Yuki Oya leg.; genomic DNA extract from one individual stored at - 20 ° C; GenBank: LC 807767 View Materials (18 S rDNA; 1,654 bp), LC 807770 View Materials (28 S rDNA; 1,667 bp); [Paratype: NSMT - DNA 56985 View Materials ] GoogleMaps .

Type locality.

Japan, Kanagawa Prefecture, Hayama, Sangashita Beach (35 ° 15 ' 58.3 " N, 139 ° 34 ' 19.6 " E).

Diagnosis.

Species of Reinhardorhynchus with a copulatory organ encompassing an armed cirrus, an unarmed accessory cirrus, and two distal hooks. Bipartite armed cirrus consisting of two sacs lined with a continuous ± 295.2 - μm-long sclerotized belt of overlapping scale-like spines. Larger sac with more spaced-out, triangular, ± 20.1 μm-long spines on the proximal end of the belt. Spines gradually decrease in size distally as the belt runs towards and folds into the smaller sac, increasing in size (± 6.1 to ± 22.2 μm long) towards the proximal tip of the smaller sac, and decreasing in size again from the proximal to the distal tip of the smaller sac. Unarmed accessory cirrus as an elongated sac. The larger distal hook is slightly curved, ± 111.5 μm long and ± 43.5 μm wide at its base; its base is provided with a slightly curved, ± 42.3 μm-long projection with a blunt distal tip forming a ~ 90 ° angle with the axis of the hook. The smaller hook is funnel-shaped, ± 58.9 μm long and ± 46.6 μm wide at its base.

Description.

General morphology. Live mature specimens are 1500–1800 µm long (n = 2), with two eyes (Fig. 3 A, B View Figure 3 ). The proboscis is 297–304 μm (n = 2) long in swimming animals and is characteristic for koinocystidids ( Brunet 1972; Karling 1980; Diez et al. 2021). The pharynx (ph, Fig. 3 A, B View Figure 3 ) is positioned near the body’s midpoint and has an approximate diameter of 231–258 μm (n = 2) in the live specimens. The oesophagus is visible as a clear zone surrounded by oesophageal glands behind the pharynx. It empties into the intestine, which is situated in the posterior portion of the body. The male and female reproductive systems are mainly located in the third posterior region of the body.

Male reproductive system. Paired testes anterior to the pharynx are on each side of the body (t, Fig. 3 A, B View Figure 3 ). A pair of sac-like seminal vesicles (sv, Fig. 3 B – D View Figure 3 ) fuse distally before entering the copulatory organ and forming an ejaculatory duct (ed; Fig. 3 C, D View Figure 3 ). The piriform copulatory organ is 323–376 μm (n = 2) long and encompasses a proximal prostate vesicle, a bipartite armed cirrus, and an unarmed accessory cirrus. Distally, it bears two large hooks of varying shapes (h 1, h 2, Fig. 3 D View Figure 3 ). The prostate vesicle consists of one type of intracapsular prostate gland (pg 1; Fig. 3 B – D View Figure 3 ) opening into the transition zone between the ejaculatory duct and armed cirrus through filiform ducts (Fig. 3 B – D View Figure 3 ; Suppl. material 1). A second type of extracapsular prostate gland (pg 2; Fig. 3 B – D View Figure 3 ) enters the copulatory organ proximally. The armed cirrus bears small spines on its entire surface (cia, Fig. 3 B – D View Figure 3 ; Suppl. materials 1, 2) and has two sacs of differing sizes, both of which are equipped with an interconnecting belt of overlapping, scale-like spines (Fig. 3 B – F View Figure 3 ; Suppl. material 1). The spines of the proximal part of the spiny belt start in the larger sac. Here, the scale-like spines are triangular, more spaced out, and 20.1 μm long (cps, Fig. 3 B – F View Figure 3 ). Gradually, these spines become less triangular, more overlapping, and decrease in size (8.8 μm long) until they reach the transition to the smaller sac, where they fold backwards and continue into the smaller sac (cms, Fig. 3 C, E, F View Figure 3 ; Suppl. materials 1 – 3). From this fold, the spines gradually increase in size (from 6.1 to 22.2 μm long) towards the proximal tip of the smaller sac, where they fold again to continue along the distal side of this sac while gradually decreasing in size again (cds, Fig. 3 C, E, F View Figure 3 ). The total length of this spiny belt is 295.2 μm. The unarmed accessory cirrus (ciu, Fig. 3 C, D View Figure 3 ; Suppl. material 1) runs alongside the armed cirrus from the proximal end of the copulatory organ to the distal end of the armed cirrus. It appears as an elongated sac that narrows proximally. It is possible that this narrow proximal part of the unarmed accessory cirrus connects to the bundles of extracapsular prostate glands (pg 2, Fig. 3 C View Figure 3 ) visible around the copulatory organ and seminal vesicles, but this connection could not be established with certainty. The larger distal hook is 111.5 μm long and 43.5 μm wide at its base (h 1, Fig. 3 G, H View Figure 3 ; Suppl. material 1). One side of the base features a sturdy, slightly curved projection with a blunt distal tip. The projection itself is 42.3 μm long and forms an ~ 90 ° angle with the axis of the hook. The smaller distal hook is 58.9 μm long and has a 46.6 μm-wide base (h 2, Fig. 3 G, H View Figure 3 ).

Female reproductive system. The vitellaria (vi; Fig. 3 A View Figure 3 ) extends from the rear end of the pharynx to the posterior body end. Paired ovaries with oocytes arranged in a single line are situated anterior to the copulatory organ (ov, Fig. 3 B, C View Figure 3 ). The bursa (bu, Fig. 3 B View Figure 3 ) opens into the female atrium through a muscular bursal stalk (bs, Fig. 3 B View Figure 3 ). The female atrium also receives the female duct (fd, Fig. 3 B View Figure 3 ), which consists of a narrow distal duct in which bundles of female glands (fg, Fig. 3 B View Figure 3 ) discharge, and a wide, muscular proximal part that receives the oviducts.