Pseudostegias atlantica Lemos de Castro, 1965

Ribeiro, Felipe Bezerra, Campos-Filho, Ivanklin Soares & Bezerra, Luís Ernesto Arruda, 2019, New records of two species of parasitic isopods (Isopoda: Cymothoida: Bopyridae: Athelginae) associated with hermit crabs from the south Atlantic, Papéis Avulsos de Zoologia 59, pp. 1-7 : 2-6

Pseudostegias atlantica Lemos de Castro, 1965 ( Figs. 2‑3 , 4 )

Pseudostegias atlantica Lemos de Castro, 1965: 105 , figs. 1-8. Brasil Lima, 1965: 640.

Material examined: BRAZIL: Ceará: one female and one male, Paracuru, Pedra Rachada Beach (02°53’42”S, 40°51’31”W), coll. F.B. Ribeiro, identified by D. Roccatagliata and F.B. Ribeiro, 13/X/2008, ( UFRGS 6669 ), infesting pleon of a male of Clibanarius antillensis Stimpson, 1859 (2.7 mm CL; UFC 506 ) .

Diagnosis: Female: cephalon deeply inset in pereomere I and about two times as long as wide, eyes present, all pereomeres distinct, all pereopods similar in size, all pleomeres distinct and tapering posteriorly, lateral plates on pleomere V absent. Male: eyes present, pereon broadest at pereomere 6, all pleomeres fused, pleopods and uropods absent.

Remarks: Pseudostegias atlantica was described based on one mature female (TL 5.5 mm) and male (3 mm) from Mucuripe beach, Fortaleza, state of Ceará, and one immature female and male from Garça Torta beach, Maceió, state of Alagoas ( Lemos de Castro, 1965). The specimen examined here is morphologically similar to the material described by Lemos de Castro (1965), showing the cephalon with anterior margin straight, dorsal region of cephalon concave with pereomeres 1-5 directed laterally forewards, all pereopods are similar in size, pleomeres distinct, lateral plates present in pleomeres 1-5 and pleopods with leaf-like endopodites and exopodites ( Fig. 2 ). Regarding the male specimen, it is similar to the allotype of P. atlantica in having the cephalon of approximately two times as wide as long with rounded anterior mar- gin and all pleomeres fused ( Fig. 3 ); however, it differs in the absence of the dorsal carina on the pleotelson. It is very likely that the specimen analyzed by Lemos de Castro (1965) showed an artifact of preservation for this character. Additional morphological characters not mentioned in previous descriptions for the female include: antennule of three articles and antenna of six articles ( Fig. 2C, D ), oostegite 1 bilobed with anterior lobe subtriangular, posterior lobe with inner margin concave, oostegites 2-3 subrectangular and oostegites 4-5 subtri- angular ( Fig. 2 E-I); and for the male, antennule of three articles and antenna of four articles ( Fig. 3C, D ), all pereopods subequal in size and shape ( Fig. 3B ), and pereopods 1 and 7 bears three setae in the distal margin of carpus ( Fig. 3E, F ). The barbula and maxilliped were not illustrat- ed due to the condition of the material.

Pseudostegias is a genus of by pleonal parasites of diogenid hermit crabs of the genera Calcinus Dana, 1851 , Clibanarius Dana, 1852 , Diogenes Dana, 1851 , Paguristes Dana, 1851 ; pagurid hermit crabs of the genus Strigopagurus Forest, 1995 ; and lithodid anomurans of the genus Hapalogaster Brandt, 1850 ( Markham, 2003) . All specimens used in the original description of P. atlantica were found associated to a host identified as Clibanarius sp. ( Lemos de Castro, 1965). The specimens in our study were found infesting the hermit crab Clibanarius antillensis Stimpson, 1859 from Pedra Rachada Beach, Paracuru, state of Ceará. This new record is about 100 km from the previous record in this state.

Distribution: Western Atlantic: Brazil (states of Ceará and Alagoas) ( Fig. 4 ).

Figures

Figure 2. Pseudostegiasatlantica Lemosde Castro,1965,female(UFRGS6669):(A)habitus dorsalview;(B)habitusventral view;(C)antennule;(D) antenna;(E)oostegite 1; (G) oostegite2; (G) oostegite3; (H) oostegite 4;(I) oostegite 5;(J)pereopod 1; (K) pereopod7.Scale bars:Aand B= 2 mm;Cand D =0.125 mm;E-I =1 mm.

Figure 3. Pseudostegias atlantica Lemos de Castro,1965, male (UFRGS 6669):(A) habitus dorsal view; (B) habitus ventral view; (C) antennula;(D) antenna; (E) left pereopod 1; (F) left pereopod 7.Scale bars:A and B = 0.5mm;C and D = 0.025 mm;E and F = 0.05 mm.

Figure 4. Distribution map of parasites (Parathelges foliatus and Pseudostegias atlantica) (circles and squares) and associated hosts (hermit crabs) (stars).Black circles and squares represent previous records and white circles and squares newrecords for parasites.White and black stars represent the distribution ofClibanarius antillensisand C.symmetricusrespectively from Venezuela toBrazil accordingto Coelho et al.(2007),Negri et al.(2014),Nucci & Melo (2015) and Lemaitre & Tavares (2015).