A new species of Eriococcus (Hemiptera: Sternorrhyncha: Coccoidea: Eriococcidae) and redescriptions of Eriococcus roboris Goux and E. thymelaeae Newstead, with a key to the Eriococcus species on Quercus in the western Palaearctic Author Hodgson, Chris Department of Biodiversity and Biological Systematics, The National Museum of Wales, Cardiff, CF 10 3 NP. E-mail: hodgsoncj @ cardiff. ac. uk University of Forestry, Plant Protection Department, Sofia, Bulgaria. E-mail: k _ trencheva @ yahoo. com Author Trencheva, Katia text Zootaxa 2008 2008-12-08 1959 1 1 38 https://biotaxa.org/Zootaxa/article/view/zootaxa.1959.1.1 journal article 10.11646/zootaxa.1959.1.1 1175­5334 5241258 Key for separation of adult female Eriococcidae on Quercus sp. in western Palaearctic: 1. Anal lobes neither sclerotised nor elongate; anal ring setae subequal to or shorter than width of anal ring; with a group of cruciform pores medially on head and on all thoracic segments; macrotubular ducts absent from venter; dorsal spinose setae capitate ..................................... Kotejacoccus turcicus Kaydan & Kozár - Anal lobes sclerotised and elongate; anal ring setae each much longer than width of anal ring; cruciform pores restricted to submargins; macrotubular ducts present on venter; dorsal spinose setae not capitate.2 2. Minute sclerotised pores present in a group on posterior coxae and posterior femur; small macrotubular ducts present throughout venter; spinose setae present in a fairly broad submarginal band ventrally on thorax and head; outer orifice of microtubular ducts without wing-like extensions .......................................... ................................................................................................................. Eriococcus thymelaeae Newstead - Minute pores absent from posterior coxae and posterior femur; small macrotubular ducts on venter restricted to medially on abdomen and metathorax; spinose setae not present in a fairly broad submarginal band ventrally on thorax and head; outer orifice of microtubular ducts with wing-like extensions...........3 3. Smallest ventral macrotubular ducts very few, with generally fewer that 10 across width of abdominal segments III and IV, and absent from segment VII.....................................................................................4 - Smallest ventral macrotubular duct common medially on all abdominal segments, generally with more than 15 across width of abdominal segments III and IV, and also present on segment VII .......................... .............................................................................................................................. Eriococcus roboris Goux 4. Ventral medium-sized macrotubular ducts only present submarginally, mainly on head and posterior abdominal segments; without a seta on antennal segment III E. melnikensis Hodgson & Trencheva , sp. n. - Ventral medium-sized macrotubular ducts present medially on most abdominal segments; with setae on antennal segment III ...................................................................................................... E. aceris (Signoret)