Sabulirhynchus ibarrae, Diez & Sanjuan & Monnens & Artois, 2023

Diez, Yander L., Sanjuan, Claudia, Monnens, Marlies & Artois, Tom, 2023, New species of Polycystididae (Platyhelminthes: Kalyptorhynchia) from Cuba and the Pacific coast of Panama, European Journal of Taxonomy 856, pp. 67-86 : 78-80

Sabulirhynchus ibarrae sp. nov.

urn:lsid:zoobank.org:act:1EA7110C-D687-42BB-87A7-1259A24E4E0E

Figs 3E–F , 4

Diagnosis

Species of Sabulirhynchus Artois & Schockaert, 2000 with a very long proboscis, representing 40% of the body length. Prostatic stylet type III plate-shaped, ~53 µm long, proximally tubular and with a ridge at its midlength. Seminal reservoir exhibits a proximal apparently sclerotised cap.

Etymology

Species named after the late Dr María Elena Ibarra Martín (Marine Research Centre, Havana University, Cuba), head of the MRC for more than 25 years, who indefatigably championed the protection of oceans. Awarded with the National Prize of Environmental Sciences of Cuba in 2007. The Research Group of Marine Ecology of Universidad de Oriente carries her name.

Material examined

Holotype CUBA • 1 whole mount; Santiago de Cuba, Siboney; 19°57′34″ N, 75°42′07″ W; 7 Feb. 2019; depth 3 m; sublittoral, coarse-grained sand, salinity 34 ‰; https://id.luomus.fi/KV.700; FMNH.

Other material CUBA • 1 whole mount; same collection data as for holotype; photographs of live specimens available; HU XIX.2.08 .

Description

The specimens are unpigmented ( Fig. 4A ), ~ 1.5 mm long. The proboscis ( Fig. 4A–B : pr) attains 40% of the body length. Caudally to the proboscis there is a pair of eyes ( Fig. 4A–B : e). The pharynx is at the midbody ( Fig. 4A–B : ph).

A testis ( Fig. 4A–B : t) is located beside the pharynx and occupies the middle third of the body. The prostatic stylet type III ( Figs 3E–F , 4C; 4A–B, 4D : ps3) is plate-shaped, 49–56 µm long (x = 53 µm; n = 2), and 20–21 µm wide proximally; it is proximally tubular and exhibits a ridge at its midlength.

The vitellarium ( Fig. 4A–B : vi) runs from the posterior end of the proboscis to the caudal body end. The oval ovary ( Fig. 4B, D–E : ov) has the oocytes organised in a row. The female bursa ( Fig. 4A–B, D : b) is positioned caudally to the male atrial organs. The spindle-shaped seminal receptacle ( Fig. 4B, D–E : sr) is filled with sperm and proximally exhibits a seemingly sclerotised cap ( Fig. 4D–E : sc). The gonopore opens at 80% ( Fig. 4B : cg).

Remarks

Until now, the genus Sabulirhynchus included a single species: Sabulirhynchus axi . Sabulirhynchus ibarrae sp. nov. and S. axi share the diagnostic features of the genus: lack of accessory glandular organ in the male system, a plate-shaped prostatic stylet type III, and a pyriform seminal receptacle in the female atrium ( Artois & Schockaert 2000). Considering the newly analysed material of both species, we add to the diagnosis of Sabulirhynchus the presence of a proximal, apparently sclerotised cap in the seminal receptacle. This feature is easily recognisable in live specimens; however, we did not distinguish it on the whole mounts. Therefore, the sclerotised nature of this structure is questionable.

The prostatic stylet is similar in length in both species, 52–63 µm long in S. axi (population from the Galapagos) and ~53 µm in S. ibarrae sp. nov. However, it is more variable in the population of S. axi from Panama (46–76 µm long). The stylet of S. axi is a simple plate, distally turned backward ( Artois & Schockaert 2000), whereas it is straight, proximally tubular, and with a ridge at its midlength in S. ibarrae sp. nov. These differences in stylet morphology warrant the status of a new species.

Figures

Fig. 3. Species of Typhlopolycystidinae Evdonin, 1977. A–D. Sabulirhynchus axi Artois & Schockaert, 2000 (stylet of the specimens from Panama). E–F. Sabulirhynchus ibarrae sp. nov., prostatic stylet type III from the holotype (FMNH).

Fig. 4. Species of Typhlopolycystidinae Evdonin, 1977. Sabulirhynchus ibarrae sp. nov. A–B. Live animal. C. Holotype (FMNH), prostatic stylet type III. D–E. Details of the genital systems.