Simothraulopsis demerara (Traver)

Domínguez, Eduardo, Grillet, Maria-Eugenia, Nieto, Carolina, Molineri, Carlos & Guerrero, Edmundo, 2014, Ephemeroptera from the Venezuelan Guayanas´s Uplands: Families Leptophlebiidae, Euthyplociidae and Oligoneuriidae, Zootaxa 3827 (3), pp. 301-317 : 313

Simothraulopsis demerara (Traver)

Thraulus demerara Traver, 1947: 150 ; 1960 b: 73.

Simothraulopsis demerara ; Domínguez et al., 1997: 146.

Simothraulopsis surinamensis Demoulin, 1966: 18 (nymph).

Material. Venezuela, Edo Bolívar, Kavanayén stream, 5º37’27’’N – 61º44’37’’W, 1355 m, 21/XI/2005, 1 female subimago, 1 nymph. Small stream near Kavanayén locality, 5º38’08’’N – 61º40’47’’W, 1355 m, 19/III/2005, 2 nymphs. Maremán-Parú stream, 5º44’49’’N – 61º24’06’’W, 1308 m, 27/VI/2007, 1 male imago, 2 nymphs. Kamá river , 5º25’11’’N – 61º13’05’’W, 1035 m, 20/III/2006, 12 nymphs. Kaui stream, 5º28’34’’N – 61º16’20’’W, 1196 m, 24/XI/2005, 2 nymphs. Maraupan stream, 5º12’36’’N – 61º05’38’’W, 1194 m, 20/III/2006. Pacheco stream, 5º10’29’’N–61º29’51’’W, 1144 m, 21/III/2006, 4 nymphs. Soroape river , 5º06’29’’N – 61º34’40’’W, 935 m, 21/III/ 2006, 1 nymph. Kako-Parú stream, 4º54’00’’ N – 61º05’25’’W, 913 m. 25/XI/2005, 1 nymph. Idem , except date 28/ VI/2007, 1 male subimago. Small stream in the road to the Paují locality, 4º36’45’’N – 61º05’25’’W, 942 m, 17/III/ 2006, 3 nymphs. Tarotá stream, 5º49’15’’N – 61º25’04’’W, 1324 m, 18/III/2006, 8 nymphs. Idem , except date 27/ VI/2007, 2 male imagos, 15 nymphs. Parupá river , 5º40’49’’N – 61º32’39’’W, 1281 m, 29/VI/2007, 7 nymphs. Specimens were deposited at the MLBV ( Venezuela) and IBN ( Argentina).

Discussion. Simothraulopsis demerara was originally known from Surinam and Guyana ( Traver, 1947). Later, Domínguez et al. (1997) studied material from several other countries ( Brazil, Colombia, French Guiana and Venezuela), extending its distribution. This species appears to be fairly common in the area here studied. There are some variations in the nymphs coloration collected, that could represent a different species. Nevertheless, as there are no imagos available from the different variations, we preferred not to describe them as different species. The imagos can be separated from the other species of the genus by the following combination of characters: 1) forceps sockets not fused; 2) femora with subapical brown bands. In the nymphs: 1) Posterolateral projections on abdominal segments VIII–IX; 2) femora with subapical brown bands.

Ecology. Imagos and nymphs were collected in both (dry and rainy) seasons. They were sampled in the whole size gradients of rivers we studied in the Gran Sabana region, which was, from the small sandy stream to the large rocky rivers. Consequently, they showed different riparian vegetation (varying from streams partially shaded to rivers not shaded at all) but acidic waters (pH = 5).