Duplominona pseudotrimera Curini-Galletti, 2020

Curini-Galletti, Marco, Carcupino, Marcella, Stocchino, Giacinta A., Leasi, Francesca & Norenburg, Jon L., 2020, New species of Duplominona Karling, 1966 (Platyhelminthes, Proseriata) from the Pacific coast of Panama, Zootaxa 4881 (3), pp. 482-498 : 490-492

Duplominona pseudotrimera Curini-Galletti n. sp.

( Fig. 6 )

Holotype. Gulf of Panama: Iguana Island (Lat. 7°37’45.35”N; Lon. 79°59’50.76”W), at a depth of about 4 m, medium to coarse sand, February 2016, one whole mount ( USNM 1622594 ).

Paratypes. Same data as holotype, two specimens sagittally sectioned ( USNM 1622595 ; USNM 1622596 ); one whole mount ( USNM 1622597 ) .

Etymology. The specific epithet refers to the similarity of the new species with D. trimera n. sp.

Description. A robust Duplominona , about 2.5 mm long. Rhabdoids rod-shaped. Tail tripartite, similar to the previous species. Pharynx small, just posterior to midbody.

Male genital system. With about 30 testes in two symmetrical rows. With a large spiny cirrus, up to 60 μm long, provided with spines and a tubular stylet ( Fig. 6 D, F, G ). The stylet is 25–28 μm long, slightly recurved; it is poorly sclerified and hidden by spines, and details of its morphology could not be observed. The distalmost part of the ductus ejaculatorius is lined by a thin sclerotized lamina, which protrudes outside the stylet ( Fig. 6 D : ded). Similarly to the previous species, the stylet is surrounded by proximal spines. These are relatively few, and arranged into 6–8 rows of large to very large (ranging 7–22 μm in length) spines, narrowing distally into long, acute spikes (Fig, 6 C, D).

Accessory organ 30–40 μm across, abutting the copulatory organ. The stylet is acutely pointed, about 25 μm long. Accessory organ pore close to male pore.

Female genital system. Ovaries and vitellaria as in the previous species. With a spherical bursa about 50 μm wide, lined with a high, vacuolated epithelium. Vaginal duct long and broad, caudally oriented, similar to the previous species ( Fig. 6 B, H : vd). Vaginal pore almost midway between mouth and male pore. Morphology of the female duct similar to the previous species.

Diagnosis. Species of Duplominona with tripartite tail. With up to 30 testes arranged into two rows. Large cirrus provided with a tubular stylet 25–28 μm, and 6–8 rows of large triangular spines, 7–22 μm long. Distalmost part of the ejaculatory duct sclerotized. With a spherical bursa in front of the copulatory organ and external vagina; vaginal duct long, wide, and muscular. Accessory organ stylet 25 μm long. Pore index: a: b: c: d = =4: 4: 1: 3.

Remarks. One specimen had a simple, undivided tail; the lack of adhesive glands suggested a traumatic loss of the tripartite caudal end. This event has been observed in other species with tripartite tail (MCG, pers. obs.), and makes their identification less obvious at low magnification.

Figures

FIGURE 6. Duplominona pseudotrimera n. sp. (A) Habitus of a living animal; see Fig. 2 A for interpretation of anatomical features. (B) Reconstruction of the genital areas from sagittal sections. (C) Spine morphology. (D) Reconstruction of the cirrus. (E) Micrograph of the genital area. (F, G) Micrographs of cirri. (H, I) Micrographs of sagittal sections of the bursa-vagina system (H) and copulatory and accessory organs (I). (Scale bars: C, D, F–I = 10 μm; E = 50 μm).