Eurylepta turma Marcus, 1952

Pitale, Reshma & Apte, Deepak, 2021, Further addition to the Indian fauna of Euryleptidae (Polycladida: Cotylea) with description of a new Cycloporus Lang, 1884 and Eurylepta Ehrenberg, 1831, Zootaxa 5052 (4), pp. 486-500 : 495-497

Eurylepta turma Marcus, 1952

( Figure 6 )

Material examined: One specimen (BNHS-Pclad 290, 7.76 mm x 4.82 mm) dissected for sagittal sections of reproductive structure (58 slides), collected on 8-1-2019 at Mandvi (16.988357° N, 73.274498° E), Ratnagiri district , Maharashtra .

Distribution: Originally described from Ubatuba, and Ilha de São Sebastião, São Paulo State, Brazil ( Marcus, 1952). This report marks the first record of this species in the Indo-Pacific region.

Diagnosis: Creamish translucent elongated body with pointed, pale-white tentacles. Yellowish-orange dorsal surface with red rusty pigmentation especially concentrated over the medial longitudinal region and otherwise scattered across the dorsal surface.

Description:

Colour: The cream translucent body appears yellow-orange due to intestinal contents. Red rusty pigmentation is found scattered across the dorsal surface; however, darker on the medial raised longitudinal stripe. This medial stripe fades gradually even before the half-length of the body ( Figure 6A ). Loosely arranged pale white dots are found encircling the entire translucent margin. A few white spots are prominent and seen over the dorsal surface, which represents scattered, dorsally arranged ovaries. The tentacles are pale white, tinge yellowish at the base reflecting intestinal colouration. The ventral side is translucent and yellowish intestinal branches are visible.

Form: Elongated, distally rounded.

Pseudotentacles: Erected, slender and pointed, 1.38 mm.

Eyespots: Cerebral eyespots arranged as two distinct elongate clusters, 37–40 in each cluster respectively, slightly broader at the base and placed over the frontal edge of the pharynx, 0.97 mm away from the anterior margin. Dorsal (76) and ventral tentacular eyespots (51) are found arranged in front of the proximal end of the tentacles and no eyespots are present between the tentacles ( Figure 6C ).

Digestive system: Pharynx tubular, 0.57 mm long. The main intestine stretches out along the body length, ends before the posterior margin. The intestinal ramification is simple and visible through the dorsal and ventral surface ( Figure 6D ).

Reproductive system: Gonopores: One male gonopore present immediately behind the pharynx and at a distance of 2.10 mm from the anterior margin, measuring 0.059 mm. One female gonopore 0.53 mm behind the male gonopore and at a distance of 2.67 mm from the anterior margin, measuring 0.074 mm ( Figure 6D ).

Male reproductive system: Male copulatory apparatus located posterior to male pore and inclined ventrally. The well-developed muscularised seminal vesicle is elongated, measuring 0.235 mm x 0.0716 mm. Prostatic vesicle arranged anteriorly and rounded, measures 0.115 mm x 0.105 mm. The seminal vesicle via elongated ejaculatory duct enters the penis. The short prostatic duct opens directly into the penis and meets the ejaculatory duct distally ( Figure 6F ). Penis bent enters narrow and semi-circular male atrium ( Figures 6E, F ).

Female reproductive system: Female atrium wide and opens into the vagina with broad invagination (0.0506 mm) of cement pouch ( Figure 6F ). Cement glands radiating from the female pore and densely disposed of ( Figure 6E and F ). The vagina extends (0.115 mm) dorsally to enter uteri. ( Figure 6F ). Uteri visible through the ventral surface ( Figure 6D ).

Taxonomic Remarks: The specimen matches exactly with the original description presented by Marcus (1952). About 50 cerebral ocelli in each group were counted from the adult worm refer in the original description, which is close to the cerebral eyespots of the present specimen. Furthermore, close group of eyes at a proximal area of the tentacles and the distal end is devoid of eyespots and this distinct arrangement found in the present specimen matches exactly with the original description.

This is the second formal description of the Eurylepta turma after its description from Brazil and this is the first report of the species illustrated with colour photographs.

Figures

FIGURE 6. Eurylepta turma (BNHS-Pclad 290) A. live specimen; B. in vivo-preserved specimen dorsal view; C. dorsal surface showing cerebral and pseudotentacular eyespots; D. ventral surface; E. and F. male and female reproductive structures. Abbreviations—ce: cerebral eyespots; cg: cement glands; cp: cement pouch; ed: ejaculatory duct: fa: female atrium; fp: female gonopore; it: main intestine; ma: male atrium; mo: mouth; mp: male gonopore; pe: penis; ph, pharynx; ptc: pseudotentacles; pv: prostatic vesicles; su: sucker; sv: seminal vesicle; te: pseudotentacular eyespots ut: uteri; vd: vas deferens; vg: vagina. A–D, anterior to the top; E and F, anterior to the left.