Duplominona basidilatata 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 : 484-486

Duplominona basidilatata Curini-Galletti n. sp.

( Fig. 2 )

Holotype. Pacific Ocean : Gulf of Panama, Playa Venado (Veracruz, Panama)(Lat. 8°53’27.07”N; Lon. 79°35’44.16”W), intertidal in silty coarse sand, December 2011: one whole mount ( USNM 1622570 ).

Other material. Same data as holotype, two specimens observed alive and prepared as semi-permanent mounts. Gulf of Panama, Isla Bartolomè (Las Perlas Is., Panama)(Lat. 8°40’15.88”N; Lon. 79° 3’53.55”W), intertidal in silty coarse sand and coral rubble, December 2011: two specimens sagittally sectioned ( USNM 1622571 ; USNM 1622572 ); two specimens observed alive and prepared as semi-permanent mounts .

Etymology. The name refers to the characteristic swollen basis of the cirrus spines of the new species (lat. dilatatus: dilated; widened out).

Description. A slender, small-sized Duplominona : fixed specimens up to 1 mm. Unpigmented. Anterior tip rounded; caudal tip pointed, provided with numerous adhesive glands. Epidermis of the insunk type, ciliated all over the body, except for the caudal tip. With tiny, dot-like rhabdoids all over the body. Statocyst abutting the neuropil. With a tubular pharynx in the second half of body.

Male genital system. With 3–10 testes in one medio-ventral row. With an ovoid copulatory organ of the duplex-type, with an outer and an inner muscular layer enveloping the cirrus. With a nearly spherical seminal vesicle, separated by a muscular septum from a glandular area (the ‘prostatic vesicle’)( Fig. 2 F : pv). Distally, a spiny cirrus is present, lined by the inner muscular layer. The cirrus, about 40 μm long in squeezed conditions, is provided with 5–6 girdles of 10–20 spines each ( Fig. 2 B, C ). The acutely pointed, recurved spines are provided with poorly sclerotized, flap-like bases, which may account for more than half the total length of the spines ( Fig. 2 D ). Proximal spines are smaller, 3–4 μm long including bases. Distal spines are larger, up to 8 μm long.

With a globular accessory organ, 20–30 μm, lined by a muscular coating, and provided with a slender, pen-nib shaped stylet 12–17 μm long ( Fig. 2 E ). This organ opens to the outside just in close proximity to the female pore.

Female genital system. Ovaries ventro-lateral in front of the pharynx. Vitellaria dorso-lateral, extending from in front of testes to behind pharynx. The small, spherical pre-penial bursa ( Fig. 2 F : b) is lined by a high, vacuolated epithelium. With a short, wide vaginal duct, surrounded by strong circular muscles. It opens to the outside through a vaginal pore, just in front of the male pore. The female duct is lined by an irregular epithelium and continues posteriorly to the bursa. It opens just behind the prostatoid organ pore through the female pore. The distalmost portion of the female duct is surrounded by numerous female glands.

Diagnosis. Species of Duplominona with up to 10 testes in one row. Cirrus provided with 5–6 girdles of recurved spines, 3–8 μm high, provided with comparatively very large, flat, poorly-sclerotised bases. With a spheri-cal bursa in front of the copulatory organ. With an external vagina in front of male pore. With an accessory organ provided with a stylet 12–17 μm long, opening with its own pore, in front of female pore. Pore index: a: b: c: d = =20: 2: 10: 1.

Figures

FIGURE 2. Duplominona basidilatata n. sp. (A) Habitus of a living animal. (B) Reconstruction of the cirrus. (C) Micrograph of the cirrus. (D) Spine morphology. (E) Stylet of the accessory organ. (F) Reconstruction of the genital areas from sagittal sections. (Scale bars = 10 μm).