Hoploplana divae Marcus, 1950

Bahia, Juliana, Padula, Vinicius & Delgado, Marlon, 2012, Five new records and morphological data of polyclad species (Platyhelminthes: Turbellaria) from Rio Grande do Norte, Northeastern Brazil, Zootaxa 3170, pp. 31-44 : 40-42

Hoploplana divae Marcus, 1950

( Fig. 6 )

Material examined and locality. One mature specimen (3.5 mm x 2.5mm) as sagittal sections of the reproductive structures, collected 12 March 2009 at Brazil, RN, Nísia Floresta, Praia de Búzios, 0 6o 00’41’’S, 35o06’24’’W, under rubble, on an incrusting bryozoan (Cheilostomata) (10 slides, MNRJ-PLAT 17).

Distribution. Originally described from São Paulo, Southeastern Brazil ( Marcus 1950), here reported to Rio Grande do Norte State. Also known from Curaçao ( Marcus & Marcus 1968). This species shows a broad habitat preference as the type material was found near algae ( Marcus 1950), the specimens from Curaçao were over Rhizophora ( Marcus & Marcus 1968) and our specimen was found near a rocky reef feeding upon an incrusting Cheilostomata bryozoan.

Diagnosis. Body hard, small; dorsal region pale orange with rusty orange granules; short and thin papillae; nuchal tentacles present; cerebral eyespots densely disposed.

Description. Color: Body with a pale orange coloration, somewhat transparent ( Fig. 6 A); the intestine is visible and has a rusty coloration ( Fig. 6 B). Throughout the body there are small rusty orange pigment granules, darker than the intestine ( Fig. 6 A), that disappear after fixation.

Form: Body mainly oval. Anterior and posterior ends rounded.

Tentacles: Nuchal tentacles 1 mm distant from the anterior margin ( Fig. 6 A and 6C), each one 0.25 mm long.

Eyespots: Cerebral eyespots in two sparse clusters ( Fig. 6 C). They are present anteriorly to the brain, 1.2 mm behind the anterior end of the specimen. Tentacular eyespots occur in the bases of both tentacles forming a ring cluster ( Fig. 6 C). They are arranged in two dense groups of approximately 26 ocelli each.

Digestive system: Highly ruffled pharynx ( Fig. 6 B). It measures 1.3 mm and is located 1.5 mm from the anterior end of the body. Mouth located 2 mm from the anterior end.

Epidermis and body wall: Body covered by thin and short papillae ( Fig. 6 C e 6D). Each papilla measures 0.05 mm. Body wall thick and hard on touch. Dorsal epidermis (0.02 mm) thinner than ventral epidermis (0.027 mm). Dorsal muscular layer (0.018 mm) thicker than ventral muscular layer (0.009 mm).

Gonopores: One male and one female gonopore both situated right behind the pharynx. Male gonopore 3 mm distant from the posterior end. Female gonopore located right behind the male gonopore.

Reproductive system: Spermiductal bulbs highly muscular visible by transparency in the ventral surface ( Fig. 6 B). Unfortunately, no internal detail was observed because the specimen dried prior to histological analysis and was in poor condition to be analyzed.

Taxonomic remarks. There are two species of Hoploplana reported from the Brazilian coast: H. divae and Hoploplana usaguia ( Smith 1960) . The latter is a mollusk symbiont and has a smooth dorsal surface ( Smith 1960). Our specimen fits the original description of the papillate H. divae , despite the presence of the rusty orange granules that was not cited in the original description. This kind of darker dorsal marks was noted by Hyman on sketches of Hoploplana grubei (Graff, 1892) , but on this species they were restricted to the margin ( Hyman 1939). Also, H. grubei lack papillae present in H. divae . The granules may be related to the nutritional state of the animal or may be used as cryptic coloration as to confound the animal’s body into its bryozoan prey. The hard consistency of the body wall is probably due to this species’ feeding behavior, which consists of hard-body Bryozoa. The interaction between Hoploplana species and bryozoans is acknowledged in the name of one species, Hoploplana schizoporellae ( Smith 1960) .

Figures

FIGURE 6. Hoploplana divae (MNRJ-PLAT 17). A— in vivo, dorsal view; B— in vivo, ventral view; C— preserved specimen, dorsal view with indication of cerebral and tentacular eyes; D— detail of dorsal papilla; E— H. divae in situ, on its prey, a Cheilostomata bryozoan. br: bryozoan; ce: cerebral eyespots; gp: gonopores; nt: nuchal tentacles; pa: papilla; ph: pharynx; pl: polyclad; sb: spermiductal bulbs; te: tentacular eyespots.