Benthana trinodulata, Lopes, 2003

Lopes, Paula Beatriz Araujo Elis Regina C., 2003, Three new species of Benthana Budde-Lund (Isopoda, ‘ Philosciidae’) from Brazil, Journal of Natural History 37, pp. 2425-2439 : 2430-2433

Benthana trinodulata sp. nov.

(figures 17–31, 46, 48)

Type-material. H, Brazil, RS, Maquiné (Serra do Umbu, 29°30∞S, 50°19∞W), one W, 18 September 1999, collected in leaf litter by E. R. C. Lopes (MNRJ, 15241). P: Brazil, RS: Maquiné (Serra do Umbu, 29°50∞S, 50°32∞W), two XX, 11 September 1998 (UFRGS, 2899P); (29°30∞S, 50°19∞W), three XX, 18 September 1999 (UFRGS, 2897P); (29°30∞S, 50°19∞W), one X, 11 September 1998 (UFRGS, 2898P); (29°5∞S, 50°32∞W), one W, one X, 18 September 1999 (UFRGS, 2900P). All collected in leaf litter by E. R. C. Lopes.

Diagnosis. Exopod of pleopod 1 of the male is rounded; eyes with 20 ommatidia and coxal plate VII with three noduli laterales.

Description

Maximum length. Male 6.6 mm, female 11.6 mm.

Colour. Chestnut, variegated, many unpigmented regions along the pereion; elongated unpigmented spots on the anterior region of each coxal plates; unpigmented regions on the median longitudinal line of the pereionites (figure 17). Antenna with articles 1 and 2 of the peduncle partially unpigmented; flagellum uniformly chestnut. Median region of the pleon with small unpigmented areas on pleonites 3–5; pleonites 1 and 2 with larger unpigmented regions. Pleotelson with unpigmented median region and two longitudinally elongated unpigmented lateral areas near the apex. Insertion region of the exopods and endopods of the uropods unpigmented. Pereiopods partially pigmented.

Cephalothorax. Eyes with 20 ommatidia.

Pereion. Tegument smooth and bright. Co-ordinates d/c of the noduli laterales with a maximum on coxal plate IV and one nodulus of coxal plate VII (figure 46); coxal plate VII with three noduli laterales (figure 48).

Pleon. Narrows abruptly in relation to the pereion; neopleura well-developed on segments 3–5. Pleotelson triangular with straight margins, with a groove on the distal third, and with rounded apex, reaching more than halfway down the protopodite of the uropods.

Appendages. Antennula tri-articulate, with the distal article having a series of at least nine aesthetascs at the distal half of the external margin and two apical aesthetascs (figure 18). Antenna, when extended posteriorly, exceeds the anterior margin of the fourth pereionite. Flagellum and fifth article of the peduncle of equal length. Second flagellar article smaller than the other articles, which have sub-equal length; apical organ one-third of the size of the distal article (figure 19). Mandibles: right mandible with two penicils on the incisor process and a tuft of at least ten plumose setae on the molar (figure 21); left mandible with three penicils on the incisor process and a tuft of at least ten plumose setae on the molar (figure 22). Maxillula: medial endite with two apical penicils, no distal point; lateral endite with 4+6 teeth, five being pectinate (figure 23). Maxilla: external lobe with a sinuous posterior margin and internal margin with three long and fine setae; internal lobe covered with fine setae (figure 24). Maxilliped: endite with a long seta and two short median teeth on the posterior margin, dorsally bearing a short and robust seta (as in figure 10); apex of the palp with a tuft of short fine setae (figure 25). Pereiopods: with short tricorns on all articles and a hand-shaped apical seta on the carpus of pereiopod 1 (figure 26). Sexual differentiation: pereiopods 1–4 of the male with the carpus and merus bearing a set of fissured setae; ischium and merus of pereiopod 7 of the male of sub-equal length (figure 27); ischium of the females larger than the merus. Pleopods: exopod of pleopod 1 of the male is rounded (z: y ratio=1.7) with a subapical dentiform expansion (figure 28) and the endopod with small apical spines (figure 30). Pleopod 2 with exopod distally elongated on the internal margin, carrying setae on the external margin; endopod tapered on the distal third (figure 28). Pleopod 5 exopod with four setae on the external lateral margin (figure 31). Uropod: endopod the same length as the exopod (figure 20), although some specimens have shorter endopod.

Etymology The name refers to the presence of three noduli laterales on coxal plate VII.

Remarks

This species was collected at an altitude of 400–850 m on the slopes of the Serra Geral , in the Atlantic Forest which covers the escarpment. Benthana trinodulata differs from all other known Benthana species in having three noduli laterales on each side of coxal plate VII. However, no noduli laterales are known for six species: B. albomarginata , B. bocainensis , B. schubarti , B. werneri , described by Lemos de Castro (1958), B. sulcata Gruner, 1955 and B. olfersii .