Benthana itaipuensis, Campos-Filho, Ivanklin S. & Araujo, Paula Beatriz, 2011

Campos-Filho, Ivanklin S. & Araujo, Paula Beatriz, 2011, New species of Benthana Budde-Lund, 1908 (Crustacea: Oniscidea: Philosciidae) from Paraná, Brazil, Zootaxa 2765, pp. 38-46 : 39-41

Benthana itaipuensis sp. n.

( Figs. 1–5 )

Material examined. Holotype: male, Brazil, Paraná: Foz do Iguaçu, Parque Tecnológico de Itaipu (25°26’13’’S, 54°35’50’’W, leg. D. Rodrigues, 10/III/2010, MNRJ 22538).

Paratypes: same locality and data as holotype, 1 ɗ, 2 Ψ, ( MNRJ 22539), 1 ɗ, 2 Ψ, ( MZUSP 22712), 1 ɗ, 2 Ψ, ( UFRGS 4566), and 1 ɗ, 2 Ψ (1 ovigerous) ( UFRGS 4567).

Diagnosis. Eyes with 22–24 ommatidia, antennula with 8+2 aesthetascs, antenna when extended posteriorly, reaching anterior margin of sixth pereonite, flagellum with unpigmented proximal article, outer endite of maxillula with 4+6 teeth, five teeth of inner set pectinate, and proximal tooth with 7 denticles, male exopod of pleopod 1 elongated, with distal margin of dentiform protrusion concave (relative to the insertion margin), with lobe on inner lateral margin, and sinuous (V-shaped) outer lateral margin; exopods and endopods of uropods inserting at similar level, and endopod with inner plumose fringe continuous with protopodite.

Description. Male holotype, maximum body length 5.3 mm, and cephalothorax width 1.1 mm.

Body color chestnut, distal portion of first pereonite and pleon plus pleotelson with strongly pigmented areas, cephalothorax with irregular unpigmented areas, antenna with unpigmented areas on proximal half of fourth article and on distal half of fifth to first articles of flagellum, pereon with elongated unpigmented spots on median longitudinal part of pereonites and on central part, continuing to pleon, pleonites 1–2 with three unpigmented spots, pleonites 3–5 with one elongated line on longitudinal midline, uropods with distal portions of endopod and exopod unpigmented ( Fig. 1 A, B). Cephalothorax with smooth and bright tegument bearing sparse tricorn-like setae, slightly lateral lobes, linea supra-antennalis present, linea frontalis lacking, vertex arched, linea marginalis present, clypeus and labrum similar in length, eyes with 22–24 ommatidia arranged in rows ( Fig. 1 B, C). Pereon convex with smooth and bright tegument bearing tricorn-like setae. Pleon narrower than pereon, convex, smooth and bright tegument bearing sparse tricorn-like setae, 3 to 5 well-developed neopleurae ( Fig. 1 A and D). Pleotelson triangular with slight concave lateral margin, and acute apex ( Fig. 1 E). Noduli laterales with d/c coordinates reaching a maximum on pereonite 4 ( Fig. 1 D, F; Fig. 2 A, B). Coxal plates with glandular pores and sulcus marginalis ( Fig. 1 D, G).

Antennula three-articulate, distal article longest, eight aesthetascs arranged in three rows, plus one apical pair ( Fig. 1 H). Antenna: when extended posteriorly reaching anterior margin of sixth pereonite, flagellum three-articulate, proximal article the longest, apical organ short, one-third length of distal article of flagellum, free sensilla as long as cuticular sheath, inserted from one quarter of the size of the apical organ ( Fig. 1 I).

Mandibles with molar penicil consisting of at least 10 branches, pars intermedia with dense cushion of coniform setae, additional plumose seta proximally, right mandible with three penicils on incisor process, and left mandible with two penicils ( Fig. 3 A, B).

Maxillula with medial endite with two slender penicils apically, distal part rounded, outer endite with 4+6 teeth (five of inner set pectinate; proximal teeth with seven denticles) ( Fig. 3 C).

Maxilla with lateral lobe with width subequal to the median lobe, subquadrate, robust, and distal margins sinuous, median lobe quadrate, truncated, and covered with trichiform setae ( Fig. 3 D).

Maxilliped base rectangular, cuticle scaled proximally, tricorn-like setae sparse, distal margin truncated without fringe, endite with outer and distal margins slightly prominent, strong tooth extending past distal margin, two hooks on distal margin, longitudinal ridge bearing dense setae and ending with one tooth ( Fig. 3 E).

Pereopods rather slender, tricorn-like setae on all articles, with hyaline fringe, carpus 1 with transverse antenna-grooming brush, ornamental sensory spines on carpus 1–4 dense and on merus sparse, merus exhibiting tricorn setae and carpus with bifid and trifid setae, two ornamental sensory spines on carpus 1 with hand-like apex, ischium 7 triangular, displaying around six long setae. Dactylus 1–7 with long inner claw, reaching distal margin of outer claw, dactylar organ simple, interungual setae simple and not extending past inner claw ( Fig. 4 A–F).

Pleopod 1 exopod elongated (z:y ratio = 3.4, excluding the lobe), heart-shaped, outer lateral margin without setae, inner lateral margin with lobe, dentiform protrusion with concave appearance in relation to insertion margin, and simple apex, sinuous V-shaped outer lateral margin, endopod 1 robust and displaying setae on distal portion across longitudinal section.

Pleopod 2 exopod triangular, outer lateral margin with convex appearance relative to the insertion margin, with approximately 7 sensory tricorn-like setae, endopod 2 slender and reaching fourth pleopod.

Pleopod 5 exopod triangular, outer lateral margin slightly sinuous and bearing row of four sensory tricorn-like setae and a transverse plumose fringe ( Fig. 5 A–G).

Uropods with endopod and exopod inserted at similar level, with sparse setae along inner and outer margins, protopod with inner medial sulcus lacking setae, exopod longer than endopod, with five sensory setae on apex, endopod with inner plumose fringe continuous with protopod and with three sensory setae on apex ( Fig. 5 H).

Genital papilla as in other species of the genus, with ventral shield and subapical orifices with spines ( Fig. 5 I).

Descriptive note on females. Maximum body length 7.0 mm. Cephalothorax width 1.5 mm, wider unpigmented areas than male. Pereopods 1–4 with few long ornamental sensory spines and absence of rows of bifid setae on merus and carpus; length of ischium 7 longer than in male. Pleopod 1 exopod half-moon-shaped. Distal portion of pleopod 2 exopod not elongated, with approximately six setae. Pleopod 5 exopod outer lateral margin with truncated appearance and six setae.

Remarks. Benthana itaipuensis sp. n. has some characteristics found in its congeners, such as five pectinate teeth, a lobe present on the inner lateral margin of the exopod of pleopod I of the male, the endopod and exopod of the uropod inserted at similar levels, and sexual dimorphism in pereopods 1–4 and 7.

Four species of the genus have a lobe on the male pleopod 1 exopod: B. (Benthanoscia) olfersii (Brandt, 1833) , B. taeniata Araujo & Buckup, 1994 , B. serrana Araujo & Lopes, 2003 , and B. cairensis Sokolowicz, Araujo & Boelter, 2008 . However, these species can be differentiated from B. itaipuensis sp. n. by several characters. B. (Benthanoscia) olfersii has the merus of pereopod 7 displaying a lobe, which is absent in B. itaipuensis sp. n. B. taeniata is the most similar species: on the male pleopod 1 exopod, the distal margin of the dentiform protrusion is convex, the inner lateral margin is not sinuous, 17–19 ommatidia, pereopods 1–4 with sparse ornamental sensory spines, the pleotelson with an obtuse apex, and the coloration pattern of the antenna with unpigmented spots until the proximal half of the first flagellum article; whereas in B. itaipuensis sp. n. the male pleopod 1 exopod has a concave dentiform protrusion and the distal inner lateral margin sinuous, 22–24 ommatidia, pereopods 1–4 with denser ornamental sensory spines, the pleotelson with an acute apex, and the coloration pattern of the antenna with the first article of the flagellum completely unpigmented. In B. serrana the dentiform protrusion of the pleopod 1 exopod is bent downwards at the apex, whereas in B. itaipuensis sp. n. it is simple. As for B. cairensis , the dentiform protrusion on the male pleopod 1 exopod is slender and acute and its outer lateral margin bears setae; whereas in B. itaipuensis sp. n. this protrusion is robust and without setae.

Etymology. The specific name refers to the location where the specimens were collected: near to Universidade Federal da Integração Latino-Americana, at Parque Tecnológico de Itaipu.

Figures

FIGURE 1. Benthana itaipuensis sp. n. (holotype). A, Habitus. B, Cephalothorax, dorsal view. C, Cephalothorax, frontal view. D, Coxal plates I – VII. E, Pleotelson. F, Noduli laterales. G, Glandular pores. H, Antennula. I, Antenna. Scales: A = 1 mm, B and C = 0.159 mm, D, E, G – I = 0.1 mm.

FIGURE 2. Benthana itaipuensis sp. n. (holotype). A, Noduli laterales coordinates d / c. B, Noduli laterales coordinates b / c.

FIGURE 3. Benthana itaipuensis sp. n. (holotype). A, Left mandible. B, Right mandible. C, Maxillula. D, Maxilla. E, Maxilliped. Scales: 0.1 mm.

FIGURE 4. Benthana itaipuensis sp. n. (holotype). A, B, D – F, Pereopod I, II, III, IV and VII respectively. C, Dactylus. Pepereopod; Sm—ornamental sensory spines of merus; Sc—ornamental sensory spine of carpus. Scales: 0.1 mm.

FIGURE 5. Benthana itaipuensis sp. n. (holotype). A, Pleopod I exopod. B, Pleopod I endopod. C, Pleopod II exopod. D, Pleopod II endopod. E – G, Exopods III – V, respectively. H, Uropod. I, Genital papilla. Scales: 0.1 mm.