Soikiella italica Viggiani

Bernardo, Umberto, Gualtieri, Liberata, Nugnes, Francesco, Verdolini, Elisa, Riolo, Paola & Viggiani, Gennaro, 2017, A new species of Soikiella Nowicki (Hymenoptera: Trichogrammatidae) from Italy, Zootaxa 4242 (1), pp. 185-192 : 187-190

Soikiella italica Viggiani sp. n.

( Figs 1–6 )

Description. Female. Body length: 0.72±0.087 (SD) mm (n=15). Coloration: Body dark brown, head with eyes dark red and frons yellowish. Antenna with light brown flagellar segments. Mesosoma with longitudinal yellowish line medially extending from mesoscutum to propodeum. Legs dark brown except fore and middle tibiae and tarsi light brown, and apex of hind femur and hind tarsus light brown. Fore wing with light brown veins and basally with a pale infuscation. Antenna ( Fig. 1 ) inserted just below the level of the lower margin of eyes; scape elongate, 3× as long as wide, and with a very short radicle about 1/5 length of scape; pedicel subconical, about 1/2 scape length; anellus very small, about 1/5 length of radicle; funicular segment subglobular or cup-shaped, not subcylindrical, slightly wider than long, with one placoid sensillum (pls) on side; club compact, twice as long as wide or slightly longer, C1 cup-shaped, about twice as wide as long, C2 asymmetrical, as long as width of C1, C3 asymmetrical, about as long as C2, tapering at apex, with ventral surface strongly curved, dorsal surface straight and with a short terminal tubular projection, club segments respectively with 1, 2 and at least 2 pls. Mandible tridentate. Maxillary palpus 1-segmented, subcylindrical, twice as long as wide and with a terminal strong seta about twice the length of the palpus and with another shorter seta. Mesosoma half as long as metasoma; mesoscutum with reticulate sculpture, weakened on scutellum; mesoscutum and scutellum each with two pairs of setae, the anterior pair on scutellum slightly shorter than posterior pair ( Fig. 2 ). Metanotum short, the same length as propodeum. Propodeum medially extended in a prominence and dorsal surface with some striations. Mesophragma not extended beyond second segment of gaster. Fore wing ( Fig. 3 ) broad, with distal margin rounded, 1.8× as long as wide, with short venation not reaching mid-length of wing; ratios of subcostal, premarginal, marginal and stigmal veins = 20:10:10:5. Subcostal vein with 1 seta, premarginal vein with 2 setae and broad marginal vein with 3 setae on front margin. Stigmal vein with a short neck. Discal ciliation arranged in distinct rows reaching distal margin; marginal fringe short, not longer than stigmal vein. Hind wing with three complete rows of small setae on disc. Legs with relative ratios of coxa, trochanter, femur, tibia, tibial spur and (tarsal segments): front leg = 15:5:22:22:3:(7:8:7); middle leg = 10:5:22:30:5:(7:8:8); hind leg = 20:7:25:32:5:(8:8:8). Gaster rather parallel sided, pointed distally. Ovipositor ( Fig. 4 ) very short, with base inserted at level of the fifth apparent segment of gaster and as long as the front tibia.

Male. General features and coloration as for female, except antennae and the sexual structures. Body slightly smaller: 0.53±0.057 (SD) mm (n. 3). Antenna ( Fig. 5 ) with two funicular segments distinctly differentiated from 3-segmented club. F1 and F2 subequal, both transverse, about twice as wide as long, with F2 having distal margin rather convex, not straight as in F1; club conical, longer than funicle (20:13), 2.4× as long as wide, all segments slightly asymmetrical, subequal in length; funicle and club segments each bearing a whorl of strong, spiniform sensilla. Gaster less pointed distally than female. Genitalia ( Fig. 6 ) short, ovoid, length (from the base to end of parameres) 0.1 mm, 0.6× length of hind tibia, of same type as described for S. mongibelli and S. occidentalis ( Kostadinov 1990; Velten & Pinto 1990), and apparently without specific characters.

Remarks. Soikiella italica is distinguished from S. asiatica and S. mongibelli by the presence of a placoid sensillum on F1. This feature and length of the anterior pair of setae on the scutellum is shared with S. occidentalis , but it is distinguished from the latter species primarily by the following characters: F1 not subcylindrical, but cupshaped or subglobular, first club segment with one placoid sensillum, and male with second funicular segment not markedly tapering to apex.

Molecular data (18S and 28S sequences) support separate species status for S. italica because while it is morphologically most similar to S. occidentalis its 28S and 18S fragments are identical to those of S. mongibelli . A single gap for 18S (position 361) and 5 different bases (position 334, 388, 520, 539 and 779) for 28S D2-D3 distinguish S. occidentalis from S. mongibelli and hence from S. italica . However, these two very-conserved regions (compared to COI and ITS2) are often invariant between closely related species that are instead well differentiated on the basis of other genes (Heraty et al. 2007; Sumer et al. 2009; Gebiola et al. 2010; 2012).

Etymology. The species is named after the country where it was collected, Italy.

Sample Locality Coordinates Collecting Gall maker Host plant Emergence of Number of Identified date species parasitoids specimens parasitoids and sex

10-9-13 Ascoli Piceno ( Italy) 42°49̕N 13°35̕E 04/ix/2013 Artracris macrorhyncus Acer opalus obtusatus 10/ix/2013 2♀ Soikiella italica 31-10-13 Montegallo ( Italy) 42°50̕N 13°18̕E 23/x/2013 Dryocosmus kuriphilus Castanea sativa 31/x/2013 1♀ Trichogramma sp . 5-11-13 Montegallo ( Italy) 42°50̕N 13°18̕E 23/x/2013 Dryocosmus kuriphilus Castanea sativa 05/xi/2013 3♀ Trichogramma sp . 11-11-13 Montegallo ( Italy) 42°50̕N 13°18̕E 23/x/2013 Dryocosmus kuriphilus Castanea sativa 11/xi/2013 8♀ Trichogramma sp . 9-12-13 Montegallo ( Italy) 42°50̕N 13°18̕E 23/x/2013 Dryocosmus kuriphilus Castanea sativa 09/xii/2013 2♀ Soikiella italica 7-1-14 Montegallo ( Italy) 42°50̕N 13°18̕E 23/x/2013 Dryocosmus kuriphilus Castanea sativa 07/i/2014 1♀, 2Ƌ Soikiella italica 16-1-14 Montegallo ( Italy) 42°50̕N 13°18̕E 23/x/2013 Dryocosmus kuriphilus Castanea sativa 16/i/2014 1Ƌ Soikiella italica 13-5-14 Montegallo ( Italy) 42°50̕N 13°18̕E 23/x/2013 Dryocosmus kuriphilus Castanea sativa 13/v/2014 6♀, 6Ƌ Soikiella italica 19-8-2014 Montegallo ( Italy) 42°50̕N 13°18̕E 23/x/2013 Dryocosmus kuriphilus Castanea sativa 19/viii/2014 7♀, 1Ƌ Soikiella italica

COC 13-11-13 Acquasanta Terme 42°43̕N 13°26̕E 30/x/2013 Dryocosmus kuriphilus Castanea sativa 13/xi/2013 1♀ Trichogramma sp.

(Italy)

COC 26-11-13 Acquasanta Terme 42°50̕N 13°18̕E 30/x/2013 Dryocosmus kuriphilus Castanea sativa 26/xi/2013 1♀ Trichogramma sp.

(Italy)

1 Galluccio ( Italy) 41°19̕N 13°58̕E 24/iii/2016 Dryocosmus kuriphilus Castanea sativa 13/v/2016 2♀ Soikiella italica Morphospecies Locality Country Gall maker species Host plant Sex Emergence GenBank accession numbers

data 18S 28S D2-D3 ITS2 COI Type material. Holotype (♀), on slide, ITALY: Interprete , Montegallo, 23.x.2013, from galls of D. kuriphilus , laboratory emergence 13.v.2014, collector E. Verdolini . Allotype (♂): same data as holotype . Paratypes: same place, date, host and collector as holotype except laboratory emergence 9.xii.2013 (1♀); same collecting date, place, host and collector as holotype except laboratory emergence 13.v.2014 (4♀ and 3♂); same collecting date, place, host and collector as holotype except laboratory emergence 19.viii.2014 (3♀).

Additional material. San Pietro (AP), 04.ix.2013, from maple leaves with galls of Artracris macrorhyncus (Nalepa), laboratory emergence 10.ix.2013, E. Verdolini coll. (2♀); same place, date, host and collector as holotype except laboratory emergence 09.xii.2013 (1♀); same collecting date, place, host and collector as holotype except laboratory emergence 07.i.2014 (1♀ and 2♂); same collecting date, place, host and collector as holotype except laboratory emergence 13.v.2014 (1♀ and 2♂); same collecting date, place, host and collector as holotype except laboratory emergence 19.viii.2014 (4♀ and 1♂); same collecting date, place, host and collector as holotype except laboratory emergence 16.i.2014 (1♂); Galluccio (CE), 24.iii.2016, from galls of D. kuriphilus , laboratory emergence 13.v.2016, U. Bernardo coll. (2♀).

The holotype, allotype, 5♀ paratypes and all additional material is deposited in the entomological collection of the Dipartimento di Agraria-Sezione Biologia e Protezione dei Sistemi Agrari e Forestali, Portici (NA), Italia ; other paratypes (1♀ and 1♂ for each institution) will be deposited as follows: National History Museum, London; Entomology Research Museum, University of California, Riverside; and National Museum of Natural History , Washington, D. C.

Other material examined. For morphological comparison with congeneric species the following material was examined:

Soikiella mongibelli : Italy, Camigliatello Silano , 23.vi.1988, J. D. Pinto coll. (1♀ and 1♂, on slide) ; Calabria (CS), La Sila, Lorica , 1300 m, 23.vi.1988, J- D. Pinto coll. (2♀) ; Calabria (CS), Piano di Campolungo , 23.vi.1988, J- D. Pinto coll. (1♀) ;

Soikiella occidentalis : USA, Wa., Yakima Co., Yakima, 20.vii.1988, sweeping primarily Salix along river, R. K. Velten coll (2♀ paratypes, on slide). Additional material from USA on slide: 19♀ and 14♂ .

Host. The present study records the first host plant from which specimens of Soikiella emerged. It seems reasonable to exclude D. kuriphilus and other gall makers as hosts of the new species as the galls were collected when the eggs of cynipids were absent. Very probably the chestnut galls induced by D. kuriphilus are used by other insects (e.g. Diptera ) as oviposition sites ( Nakamura & Nakamura 1977; Bernardo et al. 2013). Their eggs are likely the actual host of Soikiella . The short ovipositor and antennae, the latter with a rather asymmetrical club, in Soikiella species suggest that the host eggs should be well exposed to the parasitoid. As reported by Velten & Pinto (1990) one female of S. mongibelli from Israel was recorded from eggs of M. negevensis . No other host record is known. Based on the emergence dates in the laboratory, it is supposed that the new species produces more than one generation per year.

Figures

FIGURES 1 – 4. Soikiella italica female: 1, antenna (scale bar: 50 µm); 2, scutellum (scale bar: 50 µm); 3, fore wing (scale bar: 100 µm); 4, ovipositor (scale bar: 50 µm).

FIGURES 5 – 6. Soikiella italica male: 5, antenna (scale bar: 50 µm); 6, genitalia (scale bar: 50 µm).