Polybranchia samanthae Medrano, Krug, Gosliner, Biju Kumar & Á. Valdés, 2018

Polybranchia samanthae

No field photograph submitted for this species yet

Description

A small to medium-sized sacoglossan about 17 mm in length. The body is pale olive-green to tan or brown, with small white papillae evenly distributed on the dorsum. The rhinophores are translucent with white-frosted dorsal tips and several white papillae throughout. Snowy white pigment below the eyespots extends towards the snowy white pericardium.
The cerata are translucent and olive-green or dark tan in colour. The dorso-medial surface of each ceras bears a large green patch enclosed by dense white pigment; the white colour extends from the distal tip and stops before reaching the ceratal base, and diminishes before reaching the white margin. Two medial papillae on each ceras, one large and one small, are white but rendered inconspicuous by the surrounding white dorso-medial surface. The peduncle depression lacks pigment. The foot has a few white dots and many small dark-brown spots.

Distribution

Type locality: Maui, Hawaiian Islands. The species is exceptionally widespread in the Indo-Pacific, recorded from the Red Sea and Saudi Arabian coast, the Indian Ocean, the Central Pacific (Hawaiian Islands), tropical Australia, the Marshall Islands, and American Samoa. It is found subtidally under rocks in areas of high water-flow with ample rock cover and high algal diversity.

Etymology

The specific epithet samanthae is dedicated to the memory of Samantha Solis (24 May 1992 – 13 June 1992), the beloved niece of the first author (Medrano), who died as a newborn at the age of 20 days.

Remarks

P. samanthae is the sister species of P. jensenae, also described in the same revision, and the two are often sympatric. The frosted white tips of the rhinophores and the distal green patch on the dorso-medial surface of the cerata are unique to this species. The penis is laterally compressed from the prostate sac to the blunt tip, resembling a thin ribbon — a morphology not seen in any other Polybranchia. No penial stylet is present.