Benthana serrana, 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 : 2426-2429

Benthana serrana sp. nov.

(figures 2–16, 45)

Type-material. H, Brazil, RS, São Francisco de Paula ( Serra do Pinto, 29°3∞S, 50°18∞W), one W, 24 September 1998, collected in leaf litter by E. R. C. Lopes from the Atlantic Forest (MNRJ, 15240). P: Brazil, RS: Maquiné ( Serra do Umbu, 29°51∞S, 50°31∞W), two XX, 11 September 1998 (UFRGS, 2887P); (29°50∞S, 50°32∞W), three XX, 19 September 1999 (UFRGS, 2888P); Terra de Areia ( Serra do Pinto, 29°38∞S, 50°18∞W), two WW, seven XX, 24 September 1998 (UFRGS, 2889P); (29°42∞S, 50°16∞W), one X, 19 September 1999 (UFRGS, 2892P); São Francisco de Paula ( Serra do Pinto, 29°36∞S, 50°18∞W), three WW, 10 XX, 24 September 1998 (UFRGS, 2890P); (29°37∞S, 50°18∞W), two XX, 12 January 1999 (UFRGS, 2894P); Morrinhos do Sul (29°36∞S, 49°94∞W), two WW, nine XX, 27 November 1998 (UFRGS, 2893P). All collected in leaf litter by E. R. C. Lopes.

Other samples. Brazil, RS: Maquiné ( Serra do Umbu, 29°30∞S, 50°19∞W), four XX, 18 September 1999, collected by E. R . C. Lopes in leaf litter ( UFRGS 2895 ) .

Diagnosis. Antennula with 15–16+2 aesthetascs; long antennae reaching the posterior margin of the sixth pereionite; the exopod of pleopod 1 of the male is elongated, with a lobe on the inner lateral margin and a subapical dentiform protrusion bent downwards with a fold at the apex. Exopods and endopods of the uropods are inserted at different levels.

Description

Maximum length. Male 11.6 mm, female 12.9 mm.

Colour. Chestnut, with elongated unpigmented regions on coxal plates II–VII, the unpigmented regions being more accentuated on coxal plates V–VII (figure 2). Antenna with unpigmented regions on the fifth article of the peduncle; flagellum chestnut with small unpigmented regions. Median region of the pleon unpigmented on pleonites 1–4 and part of 5. Pleotelson with the median region and two lateral rounded areas near the apex unpigmented as well as the insertion region of the exopods and endopods of the uropods. Pereiopods pigmented.

Cephalothorax. Eyes with 20 ommatidia.

Pereion. Tegument smooth and bright. Co-ordinates d/c of the noduli laterales with a slight maximum on coxal plate IV (figure 45). Coxal plate VII has one nodulus lateralis.

Pleon. Narrows abruptly in relation to the pereion; neopleura well-developed on segments 3–5. Pleotelson triangular with a slightly sinuous margin, grooved on the distal third, rounded apex, reaching more than halfway down the protopodite of the uropod.

Appendages. Antennula tri-articulate, with the distal article with a series of 15–16 aesthetascs inserted at different levels, three at a time, into the external margin and two apical aesthetascs (figure 3). Antenna, when extended posteriorly, reaches the posterior margin of the sixth pereionite. Second flagellar article smallest (figure 4); apical organ one-quarter of the length of the distal article. Mandibles: right mandible with two penicils on the incisor process and a tuft of plumose setae on the molar (figure 6); left mandible very similar to right mandible, with two penicils on the incisor process and a tuft of plumose setae on the molar (figure 7). Maxillula: medial endite with two apical penicils, laterodistal margin rounded; lateral endite with 4+6 teeth, five being pectinate (figure 8). Maxilla: external lobe with slightly sinuous posterior and lateral margins; internal lobe covered with fine setae (figure 9). Maxilliped: endite with a long seta and a sinuous lateral-distal margin, with two short teeth; dorsally bearing a short and robust seta; apex of the palp with a tuft of fine short setae (figure 10). Pereiopods with short tricorns on all articles and a handshaped apical seta on the carpus of pereiopod 1 (figure 15). Sexual differentiation: pereiopods 1–3 of the male with the carpus and merus bearing a set of fissured setae; ischium of pereiopod 7 larger than the merus in females but the same size as the merus in males (figure 16). Pleopods: exopod of pleopod 1 of the male is cordiform and elongated (z: y ratio=2.4, excluding the lobe), with a subapical dentiform expansion, the apex of which has a smooth fold and a small lobe (figure 11) on the opposite margin; pleopod 1 endopod with apical small spines (figure 12). Pleopod 2 with exopod elongated distally on the external margin; endopod tapered on the distal third (figure 13). Pleopod 5 exopod with four setae on the external lateral margin (figure 14). Uropod: insertion of the endopod and exopod at different levels; endopod reaches more than halfway down the exopod (figure 5).

Etymology

The name refers to the slopes of the Serra Geral (Great Escarpment) , the site where the species was collected.

Remarks

This species was collected at an altitude of 100–850 m on the slopes of the Serra Geral, in the Atlantic Forest which covers the escarpment. The new species Benthana serrana is similar to B. olfersii (Brandt, 1833) and B. taeniata in respect to the exopod of pleopod 1 of the male being elongated and having a lobe, and in the insertion of the exopods and endopods of the uropods being at different levels. It differs from B. olfersii because the latter has uniformly chestnut antennae, 24 ommatidia (20 in B. serrana) and a marginal lobe on the merus of pereiopod 7 (absent in B. serrana). It differs from B. taeniata in terms of the colour of the body, antennae and uropods, the maxilla having a bi-lobed contour, the pleopod lacking a fold at the extremity of the dentiform expansion and the antennula having 6+2 aesthetascs (15–16+ 2 in B. serrana).