Reinhardorhynchus soror 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 : 478-479

Reinhardorhynchus soror Diez, Reygel & Artois sp. n.

( Fig. 14 )

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Material and distribution. Observations on live specimens, whole mounted afterwards. Three whole mounts from Tombolo West ( 08°48’05”N; 79°33’15”W) (Type Locality), Taboga Island, Panama ( December 9, 2011), one of which designated holotype ( USNM 1642508 ), the others in the USNM (1642509–1642510), from medium-coarse sand with ripple marks close to swash zone, small waves, salinity 28 ‰.

Etymology. Species name refers to its similarities with R. beatrizae sp. n. Lat. soror : sister.

Diagnosis. Species of Reinhardorhynchus gen. n. with a copulatory bulb encompassing a spiny cirrus and two distal hooks. Cirrus armed with triangular, ±5-μm-long spines. It also has a ±437-μm-long belt of spines, which shows three distinct regions: 1) a proximal part with curved and hook-shaped spines fused at their bases, the largest one ±57 μm long, the others measuring 6–40 μm, 2) a middle part with 3-μm-long spines, and 3) a distal, combshaped part armed with ±39-μm-long and triangular spines. The larger of the distal hooks curved, ±87 μm long and ±68 μm wide at its base; its base provided with a funnel-like, ±70-μm-long hook. Smaller hook ±59 μm long and ±59 μm wide at its base.

Description. The specimens are 1.5–2.2 mm long ( x̄ = 1.7 mm; n = 3), translucent, with two rounded eyes ( Fig. 14A : e). The proboscis ( Fig. 14A : pr) is of the typical koinocystidid construction (see Brunet 1972; Karling 1980); it represents 15% of the body length in live specimens. The pharynx ( Fig. 14A : ph) has a diameter of 15% of the body length in live specimens and is located at 40–50%.

The testes ( Fig. 14A : t) are located rostral to the pharynx. The seminal vesicles ( Fig. 14A : sv) fuse just before entering the copulatory bulb. The male copulatory bulb is globular and 320–391 μm long ( x̄ = 356 μm; n = 2). The prostate vesicle ( Fig. 14A : pv) opens into the armed cirrus. The cirrus is of the same structure as that of R. beatrizae sp. n. The cirrus ( Fig. 14A : ci) is armed with triangular, 4–5-μm-long spines ( x̄ = 5 μm; n = 35) ( Fig. 14F : cis). The cirrus also includes a 437-μm-long belt of spines (n = 1) ( Fig. 14A : cir), which consists of three parts. The proximal part is provided with spines that are curved and hook shaped ( Fig. 14B, 14F : cps, 14G), the largest one 55–60 μm long ( x̄ = 57 μm; n = 3) and the other ones 6–40 μm long ( x̄ = 18 μm; n = 3). This proximal part forms a continuous 62–72-μm-long row ( x̄ = 66 μm; n = 3). The middle part forms a broad surface consisting of 3-μm-long spines ( Fig. 14F : cms) and measuring 109 μm (n = 1). The distal part is 129–135 μm long ( x̄ = 132 μm; n = 2) and consists of a continuous comb-shaped row of spines ( Fig. 14C, 14F : cds). The spines in this part are 20–59 μm long ( x̄ = 39 μm; n = 44) and increase in size from the most proximal one to the most distal one.

There are two large distal hooks. The larger one ( Fig. 14A & 14F : h 1, 14E) is 84–89 μm long ( x̄ = 87 μm; n = 3) and 63–77 μm wide at its base ( x̄ = 68 μm; n = 3), curved, and carries a funnel-like and 65–80 μm long ( x̄ = 70 μm; n = 3) projection at its base ( Fig. 14E–F : fh). This structure is straight, makes a ±90º angle with the main hook, and ends in a blunt tip. The hook proper is strongly curved and ends in a sharp tip. At its base, there is a small, more or less square and folded projection ( Fig. 14E : fp). The smaller hook ( Fig. 14A & 14F : h2, 14D) is 57–89 μm long ( x̄ = 59 μm; n = 3) and 54–62 μm wide ( x̄ = 59 μm; n = 3) at its base. The base of this hook is asymmetrical. The hook is slightly curved and ends in a sharp tip.

Vitellaria were not observed. The ovaries are oval shaped ( Fig. 14A : ov), located rostral to the copulatory bulb, with the oocytes organised in a row. The oviducts open into the female duct. The female duct opens into the receptacle bursa (terminology of Karling 1980) ( Fig. 14A : rb) through a strong sphincter. In a live specimen one embryo ( Fig. 14A : em), apparently not surrounded by a shell, was observed, suggesting the species is (ovo-)viviparous. The common gonopore ( Fig. 14A : cg) is located ventrally, at 90%.

Figures

FIGURE 14. Reinhardorhynchus soror sp. n.. A, general organisation (from a live animal). B & G, proximal spines of the spiny row of the cirrus. C, distal spines of the spiny row of the cirrus. D, smaller hook. E, larger hook. F, sclerotised structures of the copulatory bulb. B–G, from the holotype. All with proximal end toward top of figure.