Pseudione ivanklini

Horch, Amanda Porciuncula, Huber, Augusto Frederico, Araujo, Paula Beatriz & Ribeiro, Felipe Bezerra, 2018, A new species of Pseudione Kossmann, 1881 (Isopoda, Cymothoida, Bopyridae) parasitizing the lobster Nephropsis aculeata Smith, 1881 (Decapoda, Astacidea, Nephropidae) in the Southwestern Atlan, Zootaxa 4461 (2), pp. 245-252: 246-251

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Pseudione ivanklini

sp. nov.

Pseudione ivanklini  sp. nov.

( Figs 1–4View FIGURE 1View FIGURE 2View FIGURE 3View FIGURE 4)

Type material. Holotype. Brazil: mature female (15.1 mm TL), Thiago EJ II, lance 15, rede 1 and 2 (32°44.08’S, 50°23.01’W), 350 m, 30/VII/2016, coll. Ribeiro, ICMBio/CEPSUL, infesting right branchial chamber of male Nephropsis aculeata Smith, 1881  (50.8 mm CL; UFRGS 6584View Materials) ( MZUSP 38163View Materials). ParatypesGoogleMaps  . Mature male (4.7 mm TL), same data as holotype ( MZUSP 38164View Materials); mature female (12.5 mm TL) and mature male (6.0 mm TL), Thiago EJ II, lance 30 (32°24.77’ S, 50°13.61’ W), 435 m, 16/II/2018, coll. Luiz Moro, ICMBio/CEPSUL, infesting left branchial chamber of female N. aculeata  (42.6 mm CL; UFRGS 6585View Materials) ( MZUSP 38165View Materials).GoogleMaps 

Etymology. Named in honor of the Brazilian carcinologist Ivanklin Soares Campos Filho from the Universidade Federal de Campina Grande, Campina Grande, Paraíba, Brazil, who has contributed to the taxonomy of Brazilian isopods.

Diagnosis. Female: nearly symmetrical, broadest at pereomere 3. Cephalon bearing narrow frontal lamina extending slightly beyond pereonal margin. Maxilliped palp deeply inset in sinuous distal margin of largest article and not extending beyond it. Oostegite 1 posterior lobe inner margin concave with irregular border and inner upper margin projected anteriorly, sinuous internal ridge with seven lobes. Male: pereon broadest across pereomeres 5–7, tapering anteriorly and posteriorly. Pleomeres 4–6 fused.

Description. Female holotype ( Figs. 1B View Figure , 2 View Figure ): body length 15.1 mm, maximal width 9.8 mm at pereomere 3, head length 2.6 mm, head width 3.9, pleon length 4.6 mm. Body outline elongate-oval, body axis distorted 14° dextrally; all body regions and pereomeres distinctly recognized. No apparent pigmentation.

Cephalon suboval, deeply inset in first pereomere; frontal lamina fully developed and narrow, completely covering front of head and slightly extending beyond its sides ( Fig. 2A View Figure ); eyes absent ( Fig. 2A View Figure ); antennula of three articles ( Fig. 2C View Figure ), antenna of five articles, all covered by fine scales ( Fig. 2D View Figure ); barbula with four projections with elongated angled outer projection and three small inner projections ( Fig. 2E View Figure ). Maxilliped subquadrate with two articles; largest article bears long setae on the inner distal margin; palp unsegmented and deeply inset in sinuous distal margin of largest article not extending beyond it and bearing eight long setae; spur long and sharp ( Fig. 2F, G, H View Figure ).

Pereon elongate, broadest at pereomere 3, gradually tapering in both sides anteriorly and posteriorly; dorsolateral bosses on pereomeres 1–4 on both sides; tergal projections weakly developed in pereomeres 1–4 and on right side, well developed with acute margins in pereomeres 5–7; small coxal plates on the right side of pereomeres 1–4 ( Fig. 2A View Figure ); oostegites 2–5 with little tuberculate projections on lateral margins ( Fig. 2B View Figure ); marsupium completely closed ( Fig. 1B View Figure , 2B View Figure ); oostegite 1 anterior lobe suboval, posterior lobe inner margin concave with irregular border and inner upper margin projected anteriorly, sinuous internal ridge with seven small lobes ( Fig. 2I, J View Figure ). Pereopod 1 slightly shorter ( Fig. 2K View Figure ), pereopods 2–7 gradually increasing in size especially the ischia ( Fig. 2L View Figure ).

Pleon with five distinct pleomeres plus pleotelson; pleomeres 1–5 with extended lanceolate lateral plates with margins weakly crenulated; five pairs of biramous pleopods also lanceolate with endopods at least half of size of exopods and weakly crenulated, exopods crenulated; uropods uniramous and similar to size and shape to pleopods ( Fig 2B View Figure ).

Male paratype ( Fig. 1B, C View Figure ; 3 View Figure ): body length 4.7 mm, maximal width 1.7 mm at pereomeres 5–6, head length 0.5 mm, head width 1.2 mm, pleon length 1.3 mm. All body regions and pereomeres distinct except pleomeres 4–6, forming the pleotelson. No apparent pigmentation. Sides of body almost parallel.

Cephalon suboval, distinct from first pereomere and narrower than pereon ( Fig. 3A, B View Figure ). Eyes absent ( Fig. 3B View Figure ). Antennula of three articles ( Fig. 3C View Figure ); antenna of five articles ( Fig. 3D View Figure ), extending beyond margins of head ( Fig. 3B View Figure ). Simple setae present distally in articles 2–3 and 1–5 of antennula and antenna, respectively.

Pereon broadest across pereomeres 5–7, tapering anteriorly and posteriorly; median-posterior margin of pereomeres 1–2 directed anteriorly, straight on pereomeres 3–4 and posteriorly on pereomeres 5–7; distolateral margins rounded ( Fig. 3A, B View Figure ). Pereopods 1–3 subequal in size and shape and more robust than pereopods 4–7, which are also subequal in size and shape, more elongated and all with marked decrease in dactylus size when compared to pereopods 1–3 ( Fig. 3E, F View Figure ). All articles distinctly separated ( Fig. 3E, F View Figure ).

Pleon with first three pleomeres distinct and last three fused with telson ( Fig. 3A, B View Figure ). Pleomeres 1–3 slightly sloped and tapering posteriorly, with rounded distolateral margins; pleotelson narrower than rest of body, with bilobate posterior margin ( Fig. 3A, B View Figure ); pleopods and uropods absent ( Fig. 3A, B View Figure ).

Remarks. Pseudione ivanklini  sp. nov. is the fourth species of Pseudione  found parasitizing Nephropidae  , in the present case, Nephropsis aculeata  ( Fig. 1A View Figure ). The other species were associated with the genera Nephropsis Wood-Mason, 1872  and Metanephrops Jenkins, 1972  ( Table 1). In addition, Markham (1999) commented that Bouvier (1925) recorded an unidentified bopyrid from N. aculeata  in the Caribbean.

The overall body shape of females is morphologically similar to the other species ( Table 1). However, close analysis reveals differences between them, including comparison with the most morphologically similar species P. tanimbarensis Markham, 1999  . These include differences in the antennae, barbula, maxilliped, oostegite 1 and pleopods. The antennae in Pseudione ivanklini  sp. nov. have five articles (eight in P. tanimbarensis  ); barbula with longer outer projection; maxilliped with palp deeply inset in the sinuous distal margin of the largest article not extending beyond it (vs. palp not inset and slightly extending beyond the distal margin); oostegite 1 inner margin with irregular border and sinuous internal ridge with seven distinct lobes (vs. straight contour in inner margin and internal ridge with few tiny lobes); and pleopods more crenulated ( Table 1). The male of Pseudione ivanklini  sp. nov. is similar to P. atlantica Bourdon, 1971  and P. tanimbarensis  regarding the absence of pleopods. However, it differs from P. tanimbarensis  by having the antennae with five articles (vs. six); and differs from P. atlantica  in having the pereon broadest across pereomeres 5–7 (vs. all pereomeres subequal). This is the southernmost record of Pseudione  (~32° latitude).

Distribution. This species is recorded only from southern Brazilian waters ( Fig. 4 View Figure ).