A new species of Cirolana Leach , 1818 ( Isopoda , Cymothoidea , Cirolanidae ) from Brazilian coast

A new species of Cirolana is described from the Northeast Brazilian coast based on the material previously recorded as Cirolana palifrons and some other material misidentified as C. parva. The new species, C. lemoscastroi sp. nov., belongs to a group of species within the genus that have two dorsal longitudinal carinae on the pleotelson. A key to all Cirolana species recorded from Brazil is provided.


INTRODUCTION
The Cirolanidae are worldwide distributed isopods, including marine, estuarine and some freshwater species.Most cirolanids are marine free-living carnivores or scavengers feeding on the carcasses of animals they have not captured and killed themselves (Keable, 1998;Stepien and Brusca, 1985;Bruce, 1986a;Berrow, 1994).Some species are opportunistic and aggressive biting other animals (Miller, 1968).

MATERIAL AND METHODS
The specimens examined in this study were collected by different expeditions along the Northeast Brazilian coast.The specimens were observed under a stereoscopic microscope with a camera lucida and the drawn specimens were dissected and mounted in glycerine gel slides, after staining with clorazol black.Digital illustrations were made up according to Coleman (2003).The type material is deposited in the Crustacea collection of "Museu de Oceanografia Prof. Petrônio Alves Coelho da Universidade Federal de Pernambuco" (MOUFPE) and "Museu Nacional da Universidade Federal do Rio de Janeiro" (MNRJ).
Etymology.In honor to Dr. Alceu Lemos de Castro for his contribution to the knowledge of Brazilian isopod fauna.
Complementary description.Based on paratype male, 4.3 mm (MOUFPE 14957).Sexual dimorphism weak.Penes present, short and cone-shaped.Pleopod I protopod with 4 coupling hooks and 1 plumose seta on inner margin; single robust seta on lateral distal angle.Pleopod II protopod with 4 coupling hooks and 3 plumose setae on inner margin; single plumose seta on lateral distal angle; appendix masculina exceeding exopod by 0.13 of its length, tip narrowing to irregular point.Pleopod III protopod with 4 coupling hooks and 3 plumose setae on inner margin.Pleopod IV protopod with 4 coupling hooks and 3 plumose setae on inner margin.Pleopod V protopod with 1 plumose seta on inner margin, exopod bilobate, endopod reduced and without setae.and C. tuberculata a rounded tip of the pleotelson rounded and the absence of tubercles on the pereonites.However, in C. lemoscastroi sp.nov. the appendix masculine is 1.2X longer than the exopodite of pleopod 2 and the uropod exopod is 0.6X of endopod length.Cirolana lemoscastroi sp.nov. is shares with C. namelessensis the appendix masculina 1.2 X longer than endopodite of pleopod 2 and exopod uropod 0.6X as long as endopod.However, in C. lemoscastroi sp.nov. the antenulla is shorter than the former species, reaching only pereonite 1 (vs halfway of pereonite 1) and antenna reaching pereonite 3 (vs antenna reaching pereonite 4).

Morphological variations
An examination of the single specimen deposited in Crustacea Collection of the Museu Nacional do Rio de Janeiro, illustrated and described by Lemos de Castro and Lima (1976) as Cirolana palifrons, revealed that it fits with all diagnostics characters of the new species described herein.In their illustrations of pleonites, Lemos de Castro and Lima (1976) showed four tubercles dorsally, however we observed only three processes (longitudinal carinae).Bruce (1986) pointed out that the figured specimen by Lemos de Castro and Lima (1976) "do not agree with those of Barnard who described the species from a single damaged male from the Indian Ocean" (South Africa).Indeed, Cirolana lemoscastroi sp.nov. shares with Cirolana palifrons, two dorsal longitudinal carinae on pleotelson.However, Cirolana lemoscastroi sp.nov.clearly differs from the latter in not having: (a) the rostrum rounded produced and covering the peduncles of antennula and antenna, (b) antenna short, reaching only the 1/2 of pereonite 1 (c) two pairs of dorsal tubercles in each side of pleotelson (d) rami of uropod subequal in length.Moreover, the new species described herein is characterized by the antenna extending to pereonite 3 and by the presence of 3 dorsal longitudinal carinae on pleonite 5, whereas in C. palifrons the antenna 2 extending to pereonite 2 and pleonite 5 is dorsally smooth.
At a first glance, Cirolana lemoscastroi sp.nov.could be confused with C. parva, also recorded from Brazilian waters, since in some specimens (mainly subadults) the longitudinal carinae present on pleonite 5 and pleotelson are difficult to be seen, the new species also has only 4 segments visible on pleon and a similar shape of appendix masculina.Part of the material identified by Koening (1972) was re-examined here and corresponds to the new species.Therefore, perhaps, specimens of the new species deposited in Brazilian collections had been misidentified as C. parva.Despite of the ornamentation of the pleon and pleotelson, C. lemoscastroi sp.nov.can be distinguished from C. parva by incomplete interocular furrow on the head, and only exopod of pleopod 5 has a transversal suture (instead of pleopods 3-5).
A comparison of selected morphological characters 19 species, including the new species, with dorsal longitudinal carinae on the pleotelson is provided (Tab.1).(1980) is lost.So, this record needs to be confirmed.

Table 1 :
Comparison of selected characters of Cirolana lemoscastroi sp.nov.with other species of Cirolana with dorsal longitudinal carinae.