Encarsia biseta Li & Geng

Geng, Hui & Li, Cheng-De, 2016, Five new species of genus Encarsia Förster from China (Hymenoptera: Aphelinidae), Zootaxa 4162 (3), pp. 535-549 : 542-544

Encarsia biseta Li & Geng , sp. nov.

Figs 17–22

Type material. Holotype. ♀ [on slide], ( NEFU), CHINA, Yunnan Province, Ruili City, Nanjingli Village, 26–27. IV. 2013, Xiang-Xiang Jin , Guo-Hao Zu , Chao Zhang , YPT.

Paratype. 1♀ [on slide], CHINA, Yunnan Province, Longchuan County, Zhangfeng Town, 26–27. IV. 2013, Xiang-Xiang Jin , Guo-Hao Zu , Chao Zhang , YPT. ( NEFU).

Diagnosis. Female. Length, mesosoma plus metasoma, 0.47 mm. Frontovertex 0.6–0.65× as broad as head width; ocelli forming about a right triangle. Mandible with two teeth and a truncation; maxillary and labial palpi 1- segmented. Antennal formula 1:1:4:2. Mid lobe of mesoscutum with 2 setae; each side lobe and axilla with 1 seta; placoid sensilla on scutellum widely separated; distance between anterior pair of scutellar setae distinctly greater than that between posterior pair. Fore wing 3.59–3.67× as long as wide, sparsely setose, with a large asetose area around stigmal vein; marginal fringe 0.95–1.07× as long as wing width. Tarsal formula 5:5:5. Mid tibial spur 0.76– 0.78× as long as corresponding basitarsus. Petiole smooth. T7 1.87–1.9× as wide as long. Ovipositor not or hardly exerted, 0.86–0.92× as long as mid tibia; third valvula 0.44–0.51× as long as second valvifer.

Description. Female. Holotype. Length, mesosoma plus metasoma, 0.47 mm. Head yellow except clypeus, malar sulcus, a faint spot on each side of occipital foramen, and two bars behind lateral ocelli brown to dark brown. Antennae pale brown except radical and scape pale yellow, clava slightly darker than funicle. Mesosoma pale yellow except pronotum, anterior margin of mid lobe, mesopleuron and propodeum laterally brown, axillae slightly pale brown. Wings hyaline, with a very indistinct infuscation behind marginal vein of fore wing; venation pale brown. Legs pale yellow. Metasoma with basal segments pale brown, gradually paler distad, petiole medially and T5–T7 pale yellow. Ovipositor pale yellow.

Head ( Fig. 17 ), in frontal view, 1.1× as wide as high, slightly broader than mesosoma. Frontovertex 0.65× as broad as head width. Eyes with fine and transparent setae. Ocelli forming about a right triangle. Mandible with two teeth and a truncation. Maxillary and labial palpi 1-segmented. Antennae inserted at level of lower margin of eyes. Antennal formula, 1:1:4:2 ( Fig. 18 ); radicle (R), scape (S), pedicel (P), 4 funicle segments (F1–F4) and 2 club segments (F5–F6) with the following ratios of length to width: R: 2.35, S: 3.65, P: 1.58, F1: 1.56, F2: 1.38, F3: 1.49, F4: 1.67, F5: 1.63 and F6: 1.65; relative lengths of segments R–F6 to length of F1: R: 1.32, S: 2.85, P: 1.61, F1: 1.00, F2: 1.11, F3:1.61, F4: 1.72, F5: 1.94, and F6: 1.97; flagellum with the following numbers of longitudinal sensilla: F1: 0, F2: 0, F3: 2, F4: 3, F5: 3, F6: 3.

Mesosoma ( Fig. 19 ) 0.68× as long as metasoma. Mid lobe of mesoscutum and axillae reticulate. Mid lobe of mesoscutum with 2 setae near posterior margin, each side lobe of mesoscutum with 1 seta. Axilla with 1 seta. Scutellum 2.04× as wide as long, and 0.65× as long as mid lobe of mesoscutum. Distance between placoid sensilla on scutellum 7.31× maximum width of a sensillum. Anterior pair of scutellar setae clearly shorter than posterior pair, and distance between anterior pair 1.38× that between posterior pair. Endophragma long and rounded at apex, extending to middle of T2. Fore wing ( Fig. 20 ) 3.67× as long as wide, sparsely setose, with a large asetose area around stigmal vein; costal cell with 4 short setae in basal half; basal cell with 1 seta; submarginal vein with 2 setae; marginal vein about as long as submarginal vein, with 3 setae along anterior margin; marginal fringe long, 1.07× as long as wing width. Hind wing 8.21× as long as wide, marginal fringe 2× as long as wing width. Tarsal formula 5:5:5. Mid tibial spur 0.78 × as long as corresponding basitarsus ( Fig. 21 ), and the latter 0.34× as long as mid tibia. Hind tibia 1.03× as long as mid tibia.

Metasoma ( Fig. 22 ) with petiole smooth. T1–T5 with scale-like reticulation laterally. T2–T7 with 1+1, 1+1, 1+1, 2+2, 1+2+1 and 4 setae, respectively. T7 1.87× as wide as long. Ovipositor ( Fig. 22 ) not or hardly exerted, apparently originating from posterior margin of T4, 0.92× as long as mid tibia, and 0.68× as long as mid tibia and basitarsus combined. Third valvula 0.51× as long as second valvifer.

Male. Unknown.

Host. Unknown.

Variation. Sole paratype with mesosoma 0.82× as long as metasoma, third valvula 0.44× as long as second valvifer.

Etymology. The specific name refers to the mid lobe of mesoscutum having only 2 setae.

Comments. Encarsia biseta may be related to species of the E. parvella- group, sensu Hayat (1989, 1998) and defined by Polaszek & Gill (2011), in having all tarsi 5-segmented, fore wing with a clear asetose area around the stigmal vein, marginal fringe of the fore wing relatively long, and antennal clava 2-segmented, but can be separated from all the species of the group by having only 2 setae on the mid lobe of the mesoscutum, each side lobe of the mesoscutum with only 1 seta, and relatively longer marginal fringe of the fore wing.

The holotype of E. biseta does not run to any species in the key to the oriental species of Encarsia by Hayat (1989), but runs to the citrina -group in both the key to Chinese species by Huang & Polaszek (1998) and the key to Indian species by Hayat (2012). It differs from all the species of the E. citrina -group by having 2-segmented antennae, smooth petiole, and only 2 setae on the mid lobe of the mesoscutum.

Two species of the E. longifasciata -group, E. longifasciata and E. dewa also have 2 setae on the mid lobe of the mesoscutum, but E. biseta lacks the characters of this species group, the clypeus without 2 median teeth, mandible not tridentate, and third valvulae of ovipositor with no concave externally, nor truncate apically.

Figures

FIGURES 17 – 22. Encarsia biseta sp. nov., holotype ♀: 17, head, frontal view; 18, antenna; 19, mesosoma; 20, fore wing; 21, mid tibial spur and tarsi; 22, metasoma. Scale bars = 50 µm.