OKINAWAN
OPISTHOBRANCH OF THE WEEK

Phyllidiopsis fissuratus Brunckhorst, 1993 (photo only, size not recorded)

Opisthobranch of the Week Data

Taxonomy:

Frequency on Okinawa: Collection Data:
[brackets indicate range for all Okinawa-collected specimens of the species]


Species Account:

        Phyllidiopsis fissuratus is considered to be very rare on Okinawa's main island; several individuals have been seen but no specimens collected. The above featured animal is one taken from a relatively old photograph, taken in September of 1986; the subject was unfortunately not collected and appropriate data not recorded. Atsushi Ono (pers. comm.) reports that P. fissuratus is a common species in the Kerama Islands Group (located 30 ~ 40 kilometers west of the Okinawa capitol, Naha). With Atsushi's permission, I've added a link to one of the Kerama animals (photographed by Atsushi off Zamami Island in January of 1999).

        The following description involving the external morphology of Phyllidiopsis fissuratus is taken from Brunckhorst (1993):

        External morphology. The live specimens ranged in length from 32-79 mm. Phyllidiopsis fissuratus is elongate and evenly rounded both anteriorly and posteriorly. Phyllidiopsis fissuratus has a black background to the dorsum and many tall, pale pink tubercles. The black is seen only as numerous, irregular meandering lines between these large tubercles. Minute black areas occur on some tubercles or at the line of fusion between compound tubercles. The pale pink notal tubercles have a broad, smooth base and they taper smoothly along the stem. They are very tall. Apically, the tubercles broaden (like a mushroom) but have a very irregular surface consisting of tiny, rounded, compound tubercles. Overall, the dorsal impression is that of many tall outgrowths of pink tubercles with the intervening areas appearing as deep valleys or fissures lined in black. Small, rounded tubercles occur just inside the mantle margin. The mantle edge is smooth, very narrow and pink, but interrupted by numerous black rays. The anus occurs at the summit of a very tall (approximately 23 mm above the level of the tubercles), conical, smooth, translucent pink papilla. The rims of the rhinophoral pockets are raised (to approximately half the height of surrounding tubercles) and are pale pink. The rhinophores are tall and pink with a black stripe extending from the apex down the posterior face to the base. Each rhinophoral clavus possesses 29-32 lamellae (specimens greater than 49 mm). Ventrally, the hyponotum is pink with fine cross hatching and a few dark grey transverse rays. The gills are dark grey. The long broad foot is uniformly pink and its margin is slightly undulating. The fused, squarish oral tentacles are pink.

        Remarks. Phyllidiopsis fissuratus is a very large species. Its distinctive external features are its very tall, pale pink tubercles which broaden apically with many tiny, rounded, compound tubercles, and the resultant deep valleys, lined with black. Some tubercles also have minute black markings. A notable feature on the dorsum is the extremely tall, smooth, conical, translucent pink anal papilla. The rhinophores are pink with a black stripe posteriorly. The rhinophoral pockets possess raised, translucent pink rims. Ventral features include the pink colouration, dark grey gills, and undulating edge to the large foot. The black background colouration of the dorsum, the very tall pale pink tubercles, the greater number of lamellae to the rhinophoral clavus and the unique morphology of the anal papilla, separate this species from the two previously described species and Phyllidiopsis krempfi Pruvot Fol. Phyllidiopsis burni appears to be the closest but it has dark pink tubercles (not as tall), and black rhinophores with 17-20 lamellae on their clavus (pink with a black posterior stripe and 29-32 lamellae in the present species). Phyllidiopsis burni has neither a large, conical anal papilla nor raised rims to the rhinophoral pockets. Phyllidiopsis burni has a broader muscular oesophageal segment (more elongate in P. fissuratus) and large, broad, slightly recurved penial spines (small and strongly hooked in P. fissuratus).

        As of mid-July, 2007, the following eight described species of Phyllidiopsis have been featured on the Okinawa Slug Site:

Etymology:

Literature Cited:


Page Date: 10 Mar '03
Page Modification Date: 16 Jul 07
Digitally manipulated photo
Copyright © 2007 Robert F. Bolland