Pseudione ivanklini Horch & Huber & Araujo & Ribeiro 2018, sp. nov.
Creators: name: Horch, Amanda Porciuncula
name: Huber, Augusto Frederico
name: Araujo, Paula Beatriz
name: Ribeiro, Felipe Bezerra
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Isopoda
Bopyridae
Pseudione
Pseudione ivanklini

description: Pseudione ivanklini sp. nov.
(Figs 1–4)
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 6584) (MZUSP 38163). Paratypes. Mature male (4.7 mm TL), same data as holotype (MZUSP 38164); 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 6585) (MZUSP 38165).
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, 2): 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); eyes absent (Fig. 2A); antennula of three articles (Fig. 2C), antenna of five articles, all covered by fine scales (Fig. 2D); barbula with four projections with elongated angled outer projection and three small inner projections (Fig. 2E). 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).
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); oostegites 2–5 with little tuberculate projections on lateral margins (Fig. 2B); marsupium completely closed (Fig. 1B, 2B); 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). Pereopod 1 slightly shorter (Fig. 2K), pereopods 2–7 gradually increasing in size especially the ischia (Fig. 2L).
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).
Male paratype (Fig. 1B, C; 3): 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). Eyes absent (Fig. 3B). Antennula of three articles (Fig. 3C); antenna of five articles (Fig. 3D), extending beyond margins of head (Fig. 3B). 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). 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). All articles distinctly separated (Fig. 3E, F).
Pleon with first three pleomeres distinct and last three fused with telson (Fig. 3A, B). 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); pleopods and uropods absent (Fig. 3A, B).
Remarks. Pseudione ivanklini sp. nov. is the fourth species of Pseudione found parasitizing Nephropidae, in the present case, Nephropsis aculeata (Fig. 1A). 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).
description: Published as part of 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 Atlantic, pp. 245-252 in Zootaxa 4461 (2) on pages 246-251, DOI: 10.11646/zootaxa.4461.2.5, http://zenodo.org/record/1460056