Boninia undetermined Bock 1923

Boninia sp.

(Fig. 9)

Material examined: Seven individuals collected in Playa Carbon and Playa Langosta. One of the most abundant genera in the intertidal zone of the park (Fig. 9F)

Description: External features: Elongated body shape that gradually widens towards the posterior region, acquiring a pin outline. Average length: 1-2mm. Pigmentation whitish or reddish brown depending on the intestinal contents. Tentacles pointed and clearly separated at the anterior end. The frontal region between them acquires a sharp aspect with motion. The transverse sensory furrow, characteristic for the genus Boninia, is visible between the tentacles and behind them.

Marginal or cerebral eyes not observed. Pharynx slightly ruffled, located in the middle of the animal, extends along the entire central body third and can even invade the anterior and posterior body third (Fig. 9A, C). Sucker at the posterior end of the body.

Male gonopore behind the pharynx, female close to the male but clearly separated. Reproduction organs visible by transparency behind the pharynx. Lang’s vesicle well developed.

Taxonomic remarks: The histological processing did not allow accurate determinations since during the manipulation the material was seriously damaged. Therefore identification at the species level was not possible or confirmed, but based on the external characteristics, the Costa Rican species shows the most similarities with Boninia miriabilis Bock, 1923 from Japan and Philippines, and the Caribbean species Boninia divae Marcus & Marcus, 1968.

Boninia sp. shares with B. miriabilis and B. divae the pointed tentacles mainly frontally orientated and with a perceptible degree of rigidity. The pin shaped form of the body is also characteristic for B. miriabilis. On the other hand, the position and shape of the sensory furrow is similar to the groove of B. divae.

The anatomical characteristics of Boninia sp. appear to be a combination of the features of the Caribbean and the Pacific species.