Eretmocerus cocois Delvare

Delvare, Gérard, Genson, Gwenaelle, Borowiec, Nicolas, Étienne, Jean, Karimé, Anli- Liochouroutu Abdoul & Beaudoin-Ollivier, Laurence, 2008, Description of Eretmocerus cocois sp. n. (Hymenoptera: Chalcidoidea), a parasitoid of Aleurotrachelus atratus (Hemiptera: Aleyrodidae) on the coconut palm, Zootaxa 1723, pp. 47-62 : 50-56

Eretmocerus cocois Delvare sp. n.

( Figs 8–20 )

Material examined. Type material. – Holotype Ψ (slide-mounted in Canada balsam) ( BMNH): Petit-Canal, Parc Paysager, 20.x.2006, ex Aleurotrachelus atratus Hempel on Cocos nucifera (J. Etienne) [Ref. Etienne GP 2449, CIRAD 19307]. Paratypes ( BMNH, CIRAD, CNC, JE and MNHN). GUADELOUPE: 30 ΨΨ 3 ɗɗ (15 ΨΨ 1 ɗ slide-mounted), same references as holotype, but some collected on 03.vi.2006 [Ref. Etienne GP 2411 CIRAD 19216]; 2 ΨΨ (slide-mounted) Sainte-Anne, same host and collector, 23.i.1994 [Ref. Etienne GP 894, CIRAD 12947].

Other material (in CIRAD Monpellier and 3P Reunion). – All specimens have been reared from A. atratus . A part of them emerged from fourth instar larvae of the host. The associate plant is mostly Cocos nucifera (except otherwise mentioned). LA REUNION: 1 Ψ (slide-mounted) Bassin Martin, 15.i.2004, ex A. atratus on Roystonea oleracea (G. Delvare) ; 2 Ψ 17.x.2005 (N. Borowiec) [Ref. CIRAD 19041, 19046]; 40 ΨΨ (12 ΨΨ slide-mounted) Étang Salé, 4 m, 21.27525°S 055.38200°E, respectively 24.xi.2005, 21.iii.2006, 11.iv.2006, 29.v.2006, 02.vi.2006, 09.vi.2006 (N. Borowiec) [Ref. CIRAD 19034, 19037, 19045, 19153, 19154, 19162, 19167, 19168, 19169, 19170, 19218, 19220, 19222, 19223, 19225, 19227, 19228, 19229, 19231, 19234, 19237]; 1 Ψ Grand Bois, 21.iii.2006 (N. Borowiec) [Ref. CIRAD 19159]; 1 Ψ Piton-Saint-Leu, 07.vi.2006 (N.

Borowiec) [Ref. CIRAD 19242]; 2 ΨΨ (slide-mounted) Piton-Saint-Leu, 09/ 18.x.2006 (N. Borowiec) [Ref. CIRAD 19363 and 19366]; 2 ΨΨ (1 Ψ slide-mounted) Saint-Benoît, 20 m, 21.03790°S 055.70988°E, 02.ii.2006, 05.vi.2006 (N. Borowiec) [Ref. CIRAD 19235, 19238]; 1 Ψ Sainte-Marie, 02.ii.2006 (N. Borowiec) [Ref. CIRAD 19160]; 10 ΨΨ 3 ɗ (6 ΨΨ 1 ɗ slide-mounted) Sainte-Suzanne, Franche Terre, 52 m, 20.90169°S 55.58002°E, 31.i.2006, 05.vi.2006 (N. Borowiec) [Ref. CIRAD 19028, 19029, 19030, 19245]; 1 Ψ (slidemounted) Saint-Leu, Grand Fond, 236 m, 21.19601°S 55.30213°E, 20.x.2005 (D. Pastou) [Ref. CIRAD 19042]; 1 ɗ (slide-mounted) Saint-Pierre, 138 m 21.32423°S 55.48626°E, ex A. atratus on Dypsis lutescens , 17.xi.2005 (N. Borowiec) [Ref. CIRAD 19047]. MAYOTTE. 32 ΨΨ 1 ɗ (7 ΨΨ slide-mounted), vii–xii 2004 (A.-L. Abdoul Karimé) [Ref. CIRAD 18896, 18898].

Female ( Fig. 8 ). Length of critical point-dried specimens 0.8 mm. Body orange yellow. Pronotum and metanotum, except in middle behind dorsellum, darkened. Mid lobe of mesoscutum often slightly brownish except a median yellow stripe. Apices of mandibles dark-brown. Tarsi dirty yellow. Wings hyaline. Veins yellowish.

Head ( Fig. 17 ). Malar space about as long as height of eyes. Vertex 1.15–1.35 times as long as height of eyes. Eyes 0.60–0.80 times as wide as high in frontal view. Frons with substrigulate sculpture. Mandibles with 2 teeth and a dorsal truncation. Scrobal area bearing 10–15 hairs in addition to 2 hairs visible just above ventral margin of clypeus. Lateral outline of gena clearly rounded in frontal view. Frons bearing 10–12 pairs of hairs arranged on each side on 2 adorbital rows. Upper frons with 10–12 pairs of hairs. Scrobal lines converging above and joining together in front of mid ocellus. Oblique lines present on upper frons, joining scrobal lines to eyes. Eyes hairy, hairs about as long as diameter of a facet. Dorsal outline of vertex distinctly rounded.

Antenna ( Figs 10–12 ). Radicula 0.35–0.40 times as long as scape. Scape slightly tapering to apex, 4.5–5.5 times as long as wide. Pedicel 2.0–2.25 times as long as wide and 0.4–0.5 times as long as scape. F1 triangular, its ventral margin convex and more than 2 times as long as the dorsal one. F2 transverse, its basal and apical margins oblique and almost subparallel. Clava 5.0–6.0 times as long as wide, 1.55–1.80 times as long as scape and 3.3–4.1 times as long as pedicel. Maximal width of clava near its apex; dorsal outline of clava slightly convex, ventral outline hardly concave. Apex of clava truncate and bearing peg-like setae.

Mesosoma ( Figs 18–19 ). Mid lobe of mesoscutum with 3 pairs of setae, occasionally with supernumary setae; anterior half with reticulate sculpture, the meshes of which are larger and more visible behind pronotum; sculpture turning to substrigulate medially in posterior half, with elongate but not quite distinct meshes. Each lateral lobe with 2 setae. Each axilla with 1 seta and substrigulate sculpture. Scutellum with 2 pairs of setae and 1 pair of placoid sensilla lateral to and closer to posterior setae. Scutellum with substrigulate sculpture medially, the less distinct meshes turning isodiametric on the sides. Endophragma extending to slightly less than half of gaster length.

Mid leg ( Fig. 13 ). Mid basitarsus 0.33–0.40 times as long as tibia. Apical spur of mid tibia 0.55–0.65 times as long as mid basitarsus.

Fore wing ( Figs 14–16 ). Fore wing 2.25–2.5 times as long as wide. Longest posterior fringe 0.14–0.18 times as long as fore wing maximal width. Marginal vein 0.39–0.44 times as long as costal cell. Stigmal vein 0.45–0.65 times as long as marginal vein when stigmal vein is measured from apex of marginal vein to apex of stigma (as Graham, 1969) and 0.65–0.80 times so when stigmal vein is measured from base of last dorsal seta on marginal vein to apex of stigma (as Rose & Zolnerowich, 1997). Basal cell with 2 setae. Costal cell with 2 ventral setae in front of submarginal vein and 4–6 apical dorsal setae. Submarginal vein bearing 2 dorsal setae basad parastigma and a placoid sensillum at mid length between them. Parastigma with 3 dorsal setae. Marginal vein with 3 long dorsal setae. Fore wing disc with 10–15 hairs arranged on 2 rows basad of linea calva and 9–11 (7–13) microtrichiae below linea calva.

Gaster. Gastral tergites 1–5 with paired setae as follows: 2(1), 2(1), 2, 2(3), 2. Syntergum with 4 setae. Gastral sternites with an area bearing 10(8)–12(13) setae behind apex of phragma. Ovipositor curved upwards posteriorly, 0.75–1.0 times as long as mid tibia when seen in dorsal view on slide-mountings ( Fig. 20 ).

Male ( Fig. 9 ). – Length of critical point-dried specimens 0.8 mm. Body orange yellow dorsally. Lower face, frons, meso- and metapleuron, lateral side and ventral part of gaster pale yellow. Mandibles darkish. Scape pale yellow, pedicel moderately infuscate, flagellum dirty yellow with dark sensilla. Pronotum with 2 infuscate stripes, on each side of median line, along its posterior margin. Tegula infuscate. Metanotum slightly infuscate laterally. Propodeum strongly infuscate except in middle and on lateral margins. Legs pale yellow but tarsi moderately and uniformly infuscate. Wings hyaline, veins yellowish, setae and hairs dark. Aedeagus infuscate.

Diagnosis. The species can be separated from all described species known from the New World according to this set of characters: upper frons with oblique lines; dorsal outline of vertex distinctly convex; scape 4.5– 5.5 times as long as wide; pedicel 2.0–2.25 times as long as wide and 0.4–0.5 times as long as scape; F1 subtriangular; clava 5.0–6.0 times as long as wide with maximal width near its apex, its dorsal outline slightly convex, its ventral outline hardly concave; mid lobe of mesoscutum with 3 pairs of setae; fore wing posterior fringe relatively short, maximal length 0.14–0.18 times as long as width of wing; costal cell with 4–6 apical dorsal hairs; submarginal vein with 2 dorsal setae; gastral tergites with paired setae as 2, 2, 2, 2, 2 and 10–12 sternal setae at apex of phragma.

Discussion. When using Rose and Zolnerowich (1997), E. cocois is keyed out as E. joebelli Rose and Zolnerowich. However , in that species the submarginal vein of the fore wing bears 3 dorsal hairs basad parastigma, the longest posterior fringe is 0.3 times as width of wing, the costal cell bears only 2 apical dorsal hairs, the clava is only 1.6 times as long as scape and the first three tergites bear only 1 seta on each side. The other recent Nearctic species described and not included in the above key are also different. E. rui (Zolnerowich & Rose 2004) and E. perseae (Rose & Zolnerowich 2004) have longer pedicel and clava. Eretmocerus rosei has 2 pairs of setae only on the mid lobe of the mesoscutum ( Evans & Bennet 1996). Eretmocerus cocois shares with E. picketti Rose and Zolnerowich (2003) similar proportions of the antenna (especially of funicle and clava) and of the fore wing; however its coloration is different (pale yellow in E. picketti ), its pedicel slightly shorter and the submarginal vein has only 2 dorsal setae basad parastigma (3 in E. picketti ). Concerning the Neotropical species, the clava of E. portoricensis Dozier and E. paulistus Hempel , as figured by Dozier (1932) and Rose (2000) are clearly shorter and have much more convex dorsal outline. Eretmocerus pallidus Dozier fits the antennal habitus exhibited by E. cocois . The examination of the type series of E. pallidus showed that this species is different. The fore wing is relatively narrower and has a longer fringe, the submarginal vein bears 3 dorsal setae basad parastigma, the costal cell bears only 1–2 dorsal apical hairs, the marginal vein is relatively longer, the disc of the fore wing bears only 4–6 setae basad linea calva and the ovipositor is longer than the mid tibia. Eretmocerus pallidus is otherwise known only from its type series which was reared from a colony of Tetraleurodes sp. collected on Annona squamosa . The other Neotropical species were recently described by Rose (2000) from specimens reared from A. floccosus . They are all different from E. cocois : either they have only 2 pairs of setae on the mid lobe of the mesoscutum or their submarginal vein bears only 2 dorsal setae basad parastigma. The clava is also obviously different. Hence in the key provided by Rose (2000) for the Eretmocerus spp. parasitoids of A. floccosus , E. cocois would run at couplet 11 together with E. comperei Rose and E. dozieri Rose. These species have a shorter scape (4.2–4.3 times as long as wide) and their posterior fringe is longer (1/3 of fore wing width). Eretmocerus aleyrodiphagus (Risbec) was quoted by De Santis and Fidalgo (1994) from Aleurotrachelus socialis Bondar in Colombia. Nevertheless the remnants of the type are in such a condition that it is impossible to recognize it from the described species. Conversely Evans and Castillo (1998) and then Trujillo et al. (2004) quoted having reared an undescribed Eretmocerus from the same whitefly.

Finally, E. cocois is readily recognized from the other species reared from Aleurotrachelus spp. in Antilles by special coloration, proportions of antennal segments, the presence of 3 pairs of setae on the mid lobe of the mesoscutum, its submarginal vein bearing only 2 dorsal setae and its short fringe on the fore wing.

Biology. As far as is known, E. cocois is a highly specialized species, emerging only from fourth instar nymphs of Aleurotrachelus atratus . This result comes from various field collects and also from specificity screenings carried out in laboratory ( Youssoufa et al. 2006).

Distribution. The species is presently known from the following islands: Guadeloupe, Mayotte and La Reunion. It was probably involuntarily introduced in these last two islands, possibly together with its host.

Figures

FIGURES 8 – 16. Eretmocerus cocois Delvare sp. n. (Ψ: Figs 8, 10 – 16; ♂: Fig. 9). 8. Female habitus. 9. Male habitus. 10. Antenna. 11. Pedicel and funicle. 12. Apex of clava. 13. Mid tarsus. 14. Fore wing. 15. Base of fore wing. 16. Submarginal vein enlarged.

FIGURES 17 – 22. Figs 17 – 20. Ψ Eretmocerus cocois Delvare sp. n. 17. Head in frontal view. 18. Mesonotum. 19. Scutellum. 20. Ovipositor. Figs 21 – 22. Ψ Eretmocerus gracilis Rose. 21. Head in frontal view. 22. Antenna.