Eurylepta aurantiaca Heath & Mc Gregor 1912

Pitale, Reshma & Apte, Deepak, 2019, Intertidal Euryleptid polyclads and description of a new Stylostomum Lang, 1884 from Maharashtra, India, Zootaxa 4652 (2), pp. 317-339 : 326-328

Eurylepta aurantiaca Heath & Mc Gregor 1912

( Figure 7 )

Material examined: One specimen (2.43 mm x 1.30 mm) used for histology as sagittal sections of reproductive structures (BNHS-Pclad 161, 19 slides). Collected 30-1-2014 at Mandvi, Ratnagiri. One specimen (3.42 x 1.30 mm) (BNHS-Pclad 178) collected 23-11-2014 at Mandvi, Ratnagiri, Maharashtra.

Distribution: Originally described from Monterey Bay, California ( Heath & McGregor 1912) and later reported from Washington State and San Diego, USA ( Hyman 1953, 1955). Caribbean coast of Colombia ( Quiroga et al. 2004) and from Brazil ( Bahia et al. 2014). This report marks the first record of the species in Indian Ocean. Eurylepta violacea Kelaart, 1858 described from Southcoast of Ceylon ( Sri Lanka) is the closest report of this genus to Indian waters.

Diagnosis: Translucent oval body with typical pointed tentacles. Yellowish orange dorsal surface with pink median stripe. White dots across the dorsal surface.

Description: Colour: Transparent body, tinged with yellowish-orange which starts disappearing towards the marginal areas. Median pink stripe is prominent; begin at the base of cerebral eyespots and fades prior to posterior margin. White spots are seen throughout the dorsal surface. ( Fig. 7D and E ) Ventral surface is opaque.

Form: Oval

Pseudotentacles: finger like, slender and pointed, 0.19 to 0.27 mm

Eyespots: Cerebral eyespots arranged as two distinct elongate clusters (15–25 in each cluster), 0.30 mm from anterior margin. Dorsal and ventral tentacular eyespots (8–12) at base of tentacles, some eyespots are found between the tentacles, arranged little below the margin ( Fig. 7B ).

Digestive system: Pharynx tubular 0.83 mm long. Main intestine with about 8–9 lateral branches with further subdivisions; subdivisions do not show subsequent anastomoses ( Fig. 7E ).

Gonopores: Male gonopore present immediately behind pharynx and 1.03 mm from anterior margin, measuring 0.093 mm. Female gonopore 0.16 mm behind male gonopore and 1.25 mm from anterior margin, measuring 0.064 mm.

Male reproductive system: The present specimens found in developing stages of reproductive structure. Small form of penis (0.035 mm) and shallow male atrium (0.064 mm) observed ( Fig. 7C ). Prostatic vesicles, seminal vesicles and any other sign of reproductive structure virtually lacking.

Female reproductive system: Female reproductive organs could not be seen within the histological sections ( Fig. 7C ).

Taxonomic remarks: Smooth dorsal surface, well developed tentacles, cerebral eyes in elongated clusters, absence of frontal intestinal branch and presence of long tubular pharynx place these specimens into the genus Eu- rylepta as defined by Faubel (1984).

The specimen exactly matches the original description. The eyespot number found in the description of the type is more numerous than in the present specimen. The eyespot number is closer to the recent report of this species from Brazil ( Bahia et al. 2014). The smaller numbers of ocelli can be attributed to immature specimens.

Figures

FIGURE 7. Eurylepta aurantiaca. A. dorsal view with eyespots and tentacles; B close view of eyespot arrangement; C. sagittal sections of the body; D and E. in vivo, dorsal view; ce: cerebral eyespots; it: intestine; ma: male atrium; pe: penis; ph: pharynx; su: sucker; te: pseudotentacular eyespots. Anterior to the top in A,B,D,E and anterior to the right in C.