Pleurobranchus areolatus

Grzelak, Katarzyna & Sørensen, Martin V., 2022, Echinoderes galadrielae Grzelak & amp; Sørensen 2022, sp. nov., Zoological Studies 55 (15), pp. 1-31 : 27

Synonymy between Pleurobranchus areolatus of the present study and P. reesi

The species Pleurobranchus reesi has a general description, mainly with data of external morphology, but without any data of reproductive system. Goodheart et al. (2015) did not examine the syntypes of Pleurobranchus reesi White, 1952 , however they considered P. reesi a junior synonym of P. areolatus without adding a discussion about this synonymy. The penis of the types is not protruded out of the gonopore, thus could not be observed in detail (NHMUK 1934.9.11.102- 104). The description made by White (1952) is too general to identify the species. The most powerful argument is based on the morphology of jaw elements and the retract ability of penis. White (1952) described the jaw elements with only one denticle of each side of main cusp, this low number of denticles is unusual in P. reticulatus , which when it presents two denticles is only in some elements and not in the entire jaw, on the other hand Thompson (1977) described 1-2 denticles to P. evelinae , which is considered here a possible synonym of P. areolatus of this study. The penis is semi-contractile in all P. reticulatus examined in this study and it is completely contractile in P. areolatus of this study. The types of P. reesi do not present part of the penis exposed, and therefore probably correspond P. areolatus of this study.