Tachardiobius vladimiri S. Triapitsyn

Triapitsyn, Serguei V., 2008, A review of Tachardiobius (Hymenoptera: Encyrtidae), with description of a new species from California, USA, a parasitoid of Tachardiella spp. (Hemiptera: Kerriidae), Zootaxa 1716, pp. 44-52 : 48-51

Tachardiobius vladimiri S. Triapitsyn , sp. n.

( Figs 12–18 )

Type material. Holotype female on slide [ UCRC]: USA, California, Riverside Co., near Hemet, 11.iv.1937, C.M. Dammers (ex. Tachardiella sp. on Adenostoma sp.). Paratypes: 4 females on points [2 in UCRC, 1 in USNM, 1 in ZISP], 1 female on slide [ UCRC], and 2 males on slides [ UCRC, USNM], with the same label data as holotype. 1 male on slide [ UCRC]: USA, California, Riverside Co., Indio Hills, Curtis Palms, collected 18.iii.1927, reared (emerged) 6.iv.1927, H.J. Quayle (ex. Tachardiella larreae ). Also 8 females and 5 males on points and 1 male on slide [ USNM]: USA, Arizona, Maricopa Co., Tempe, 12.iii.1921 (except 1 female collected 12.iv.1921), E.V. Walter (under Nos. 4814 and 4815).

Diagnosis. The new taxon differs from the other two known species of Tachardiobius in having F3–F5 of the female antenna wider than long and F5 and F6 of the female antenna notably lighter than the preceding funicle segments. In both T. nigricans and T. silvestrii , F3–F5 of the female antenna are longer than wide and F5 and F6 of the female antenna are concolorous with the preceding funicle segments. It also has a 3–segmented maxillary palpus whereas T. nigricans has a 4–segmented maxillary palpus. Other distinguishing features between the three described species of Tachardiobius are indicated in the key. Tachardiobius vladimiri sp. n. could potentially be placed in the very large and diverse genus Metaphycus Mercet , as most of its funicle segments are wider than long, similar to that of Metaphycus species. However, unlike Metaphycus , the new species has very deep scrobal grooves and a well-developed interantennal prominence which, although not as narrow and sharp as in the two previously described species of Tachardiobius , is still notably narrowed dorsally (as a narrow triangle). Also, the scape of T. vladimiri is very similar to the non-dilated scape of T. nigricans and T. silvestrii and is nothing like the markedly dilated scape of the Metaphycus species. The male of T. vladimiri lacks the secretary pores in the vicinity of the torulus that are characteristic of the Metaphycus species. Additionally, if this species were placed in the presently unmanageable (in the Nearctic region) genus Metaphycus , it would be lost there and almost impossible to diagnose. In the future, the phylogenetic position of Tachardiobius needs to redefined based on rigorous molecular and morphological analyses (its relationships to Metaphycus and other genera are unclear), before the proper placement for T. vladimiri , and quite possibly for the other species of Tachardiobius , could be decided.

Description. F EMALE (holotype and paratypes). Length of dry specimens 0.86–1.00 mm (heads of all specimens badly collapsed); length of mesosoma and metasoma of the holotype 1.12 mm.

Color. Body and appendages mostly brown to dark brown, with the following parts light brown: face (partially), F5 and F6, mesopleura (partially), metanotum, propodeum (partially), trochanters, bases and apices of femora and tibiae (usually), and tarsi (distal tarsomere slightly darker). Vertex sometimes with a partially light brown or orange spot.

Sculpture and pubescence. Frontovertex, pronotum, axilla, mesoscutum, and scutellum with fine reticulate-cellulate sculpture; gastral sterna and first gastral tergum with cellulate sculpture. Mesosoma, axilla, and scutellum with short, dark setae.

Head ( Fig. 13 , badly collapsed in all specimens) about as high as wide. Vertex in frontal view about 1/3 head width. Antennal scrobes as deep grooves meeting above and interantennal prominence as a narrow triangle. Palpal formula 3: 3. Mandible with 2 teeth and an inner truncation.

Antenna ( Fig. 12 ) inserted distinctly below level of lower eye margin. Scape with reticulate sculpture, about 3.8 x as long as wide. Pedicel lightly sculptured, about 2.3 x as long as wide, much longer than any funicle segment. F1 about as long as wide, F2–F6 notably wider than long; F2–F4 subequal, much smaller than following funicle segments; F6 a little wider and longer than F5. Clava 1.8–2.4 x as long as its greatest width and about as long as combined length of 4 preceding funicle segments.

Mesosoma ( Fig. 14 ). Pronotum very short. Mesoscutum a little less than 2 x as wide as long. Scutellum about as long as wide and a little longer than mesoscutum.

Wings ( Fig. 15 ) reaching far beyond apex of gaster. Forewing about 2.4 x as long as wide, with disc hyaline; costal cell about 11 x as long as wide. Hind wing about 4.9 x as long as wide, with disc hyaline.

Legs. Mesotibial spur a little shorter than mesobasitarsus.

Metasoma ( Fig. 14 ). Ovipositor about 3/5 length of gaster, not exserted; ovipositor length: metatibia length ratio 1.0–1.1:1.

MALE. Similar to female except as follows. Body length 0.60–1.10 mm. Vicinity of torulus without secretary pores. Antenna ( Fig. 16 ) with scape reticulate, about 3.7 x as long as wide; setae on flagellar segments rather short; funicle segments wider than long and all but F1 with longitudinal sensilla; clava entire, 2.8–3.2 x as long as wide. Forewing ( Fig. 17 ) about 2.4 x as long as wide, with disc slightly infuscate at apex of venation. Genitalia ( Fig. 18 ) with 2 inconspicuous spines on each digitus.

Etymology. The species is named after my father, Vladimir Alexandrovich Trjapitzin, who has studied Encyrtidae for more than 50 years, and from whom I learned about these wasps.

Hosts. Tachardiella larreae (Comstock) and Tachardiella sp.

Figures

FIGURES 12 – 15. Tachardiobius vladimiri sp. n., female (holotype). 12. Antenna. 13. Head (rear view). 14. Mesosoma, metasoma, and legs. 15. Fore and hind wings.

FIGURES 16 – 18. Tachardiobius vladimiri sp. n., male (paratypes). 16. Antenna. 17. Forewing. 18. Genitalia.