Bledius externus Lynch, 1884

Castro, Jessica Cristina De, Caron, Edilson & Rosa, Leonardo Cruz Da, 2016, Update on the Brazilian coastal species of Bledius Leach (Coleoptera: Staphylinidae: Oxytelinae) with the description of two new species, Zootaxa 4111 (2), pp. 145-157 : 150-152

Bledius externus Lynch, 1884

( Figs. 4 , 16–21 )

Bledius externus Lynch, 1884:353 (Description, type locality: “Chacabuco”); Bernhauer & Schubert, 1911:129 (as subgenus Blediodes Mulsant & Rey, 1878 ); Bernhauer 1927:233 (as Bledius , key for Argentinian species); Herman 1986: 154 (figures), 156 (locality), 306 (catalog); Herman 2001: 1541 (catalog).

Redescription. BL: 3.60–4.00 mm, BW: 0.76–0.84 mm.

Male. Head black, antennae and legs yellowish brown, elytra reddish yellow with basal region darker, pronotum reddish dark brown and abdomen black, with the last segments of abdomen (VIII–X) yellowish brown ( Fig. 4 ). Body subcylindrical and covered with some vestiture of microsetae. Dorsum of head and pronotum with microgranulate sculpturing. Pronotum and elytra with slightly and sparsely setal punctuation.

Antenna with antennomeres 4–11 gradually increasing in length. Clypeus with anterior margin slightly curved. Epistomal suture broadly arcuate. Labrum transverse, anterior margin slightly curved (Fig. 234 of Herman 1986). Cuticular process of internal fringe of epipharyngeal lobes short and with apex not serrated. Mandibles tridentate (Fig. 236 of Heman 1986). Mentum subquadrate. Submentum extending slightly onto venter of head, posterior margin strongly V-shaped. Gular sutures fused anteriorly. Pronotum convex, wider than long (PW/PL: 1.15), anterior pronotal angles not produced, posterior margin slightly curved. Prototergosternal suture present, procoxal fissure open, protrochantin exposed (Fig. 235 of Herman 1986). Elytra about 2.0 times longer than wide (EL/BW: 2.27), elytral epipleural ridge present and complete. Tergite VII with fine fringe on posterior margin ( Fig. 16 ). Sternite VII truncate on posterior margin. Tergite VIII with posterior margin emarginate ( Fig. 17 ). Sternite VIII with pointed apical margin ( Fig. 18 ). Tergite IX with ventral struts. Posterior margin of tergite X truncate and with a small membranous projection. Aedeagus with parameres slender, median lobe with bulb base, apical portion flattened and midlongitudinally divided on ventral face ( Figs. 19 and 20 ).

Female. Identical to male. Spermatheca tripartite, basal and apical third nearly equal in size and the median third somewhat as an accordion tube ( Fig. 21 ).

Distribution. Material examined: Brazil (Rio Grande do Sul). Literature: Argentina; Uruguay ( Herman 2001).

Remarks. Bledius externus can be differentiated from B. fernandezi by the procoxal fissure open and protrochantin exposed, and from B. hermani and B. depressus , sp. nov. by the gular sutures fused anteriorly and the tergite VIII with posterior margin emarginated.

The emarginatus group is comprised by 43 species that occur both in the Old and New Worlds ( Herman 1986). Bledius externus had its distribution in Argentina and Uruguay ( Herman 1986, 2001) and here for the first time is recorded in Brazil.

Until this study, the seven known species of this group in Brazil were only distributed near rivers and according to Herman (1986), the species of this group are found near freshwater. We decided to include Bledius externus as coastal Bledius because the major part of the examined material was found on a beach named “Cassino”. This exposed sandy beach is located in the southeastern of the Rio Grande do Sul state, just south of the mouth of the Patos lagoon ( Fig. 35 ). In this location, it was also found a species of Myllaena , an aleocharine associated with edges of streams, rivers and lakes ( Caron & Klimaszewski 2008). Another material was found on estuary at the city of Rio Grande ( Fig. 35 ).

Examined material. DZUP: Three specimens “ BRASIL, RS, Rio Grande/ Estuário Lagos dos Patos/ Barra- Marisca Baixa/ VI-2012 / K. Dummel, col.” [White label, printed]; nineteen specimens “ BRASIL, Rio Grande do Sul/Rio Grande/Praia do Cassino/ 26-IV-1991 /N.M.Gianuca, col.”.

Figures

FIGURE 35. Map of the coastal region of Rio Grande do Sul where Bledius externus was collected. (Google Earth).

FIGURES 1 – 6. Habitus. 1, Bledius bonariensis; 2, B. fernandezi; 3, B. borzonei, sp. nov.; 4, B. externus; 5, B. hermani; 6, B. depressus, sp. nov..

FIGURES 16 – 21. Bledius externus. 16, tergite VII; 17, tergite VIII; 18, sternite VIII; 19 – 20, aedeagus, ventral and lateral view; 21, spermatheca. Scale = 0.1 mm.