Leptopilina lasallei Buffington and Guerrieri, 2020

Buffington, Matthew L., Giorgini, Massimo, Lue, Chia-Hua, Formisano, Giorgio, Cascone, Pasquale, Forshage, Mattias, Driskell, Amy & Guerrieri, Emilio, 2020, Description of the aberrant Leptopilina lasallei n. sp. ı with an updated phylogeny of Leptopilina Förster (Hymenoptera: Figitidae: Eucoilinae), Journal of Natural History 54 (9), pp. 565-583 : 571-579

Leptopilina lasallei Buffington and Guerrieri sp. nov.

( Figures 1 – 4 )

Diagnosis

Female. Setal band complete at base of metasoma ( Figures 1b and Figure 2e ); dorsal surface of scutellum anteriorly striate, posteriorly foveate ( Figure 2f ); posteroventral corner of metapleuron glabrous ( Figure 2e ); antenna with 10 flagellomeres ( Figure 2c ); petiole as long as wide ( Figure 2e ). Male similar to female except setal band incomplete at base of metasoma ( Figure 3a ); antenna with 13 flagellomeres ( Figure 3a ), F1 the same size as F2, not distinctly excavated laterally ( Figure 3b ). See Table 2 for a summary of characters.

Description

Female. Holotype length 1.4 mm.

General. Body overall very smooth, glabrous, lacking sculpture except on scutellum ( Figures 1 and 3 ). Head, mesosoma, metasoma dark brown, wings hyaline, legs honey yellow.

Head. In anterior view, ovate ( Figure 2a ). Head glabrous with very sparse setae scattered on face, clypeus and mandibles. Lateral margin of occiput smooth. Ratio of length of gena (I, Figure 2a ) to length of compound eye (II, Figure 2b ) 1 to 3. Gena smooth. Lateral margin of occiput evenly rounded, not well defined. Occiput smooth. Ratio of maximum diameter of a lateral ocellus (III, Figure 2b ) to shortest distance between lateral ocelli (IV, Figure 2b ) 1:2. Posterior margin of anterior ocellus clearly separated from anterior margins of posterior ocelli. Ratio of vertical distance between inner margin of antennal foramen and ventral margin of clypeus (V, FIgure 2a ) to vertical distance between anterior ocellus and antennal rim (VI, Figure 2a ) 1:4. Median keel absent. Vertical carina adjacent to ventral margin of antennal socket present, minute. Facial sculpture absent, surface smooth. Facial impression absent, face flat. Antennal scrobe absent. Anterior tentorial pits small (VII, Figure 2a ). Vertical delineations on lower face absent. Ventral clypeal margin laterally, close to anterior mandibular articulation, straight. Ventral clypeal margin medially with 6 setae. Clypeus smooth with gently curved ventral margin. Malar space adjacent to anterior articulation of mandible evenly rounded, smooth. Malar sulcus (VIII, Figure 2a ) present, simple. Ratio of distance between compound eye and posterior mandibular articulation to distance between posterior ocellus and compound eye 1:1. Compound eyes, in dorsal view, not distinctly protruding from the surface of the head ( Figure 2 ). Short, sparse setae on eyes ( Figure 2 ). Orbital furrows absent. Lateral frontal carina of face absent. Dorsal and posterior aspects of vertex smooth. Hair punctures on lateral aspect of vertex absent. Posterior surface of head deeply impressed around postocciput.

Labial-maxillary complex. Apical segment of maxillary palp with pubescence, consisting of 1 long erect seta. Apical seta on apical segment of maxillary palp longer than twice length of second longest apical seta. Maxillary palp composed of 4 segments. Last 2 segments of maxillary palp (in normal repose) straight. Apical segment of maxillary palp 2Χ longer than preceding segment.

Antenna. Terminal flagellomere with 3 basiconic sensillae. Basiconic sensillae present on F5 – F9. Articulation between flagellomeres in antenna moniliform, segments distinctly separated by narrow neck-like articulation. Antenna composed of 10 flagellomeres ( Figure 2c ); F1 2.5Χ longer than F2. Flagellomeres cylindrical, distinctly widened towards apex, clavate. Placoidal sensilla present on F5 – F10 ( Figure 2c ).

Mesosoma. Macrosculpture on lateral surface of pronotum absent dorsally and laterally ( Figure 1 ). Anteroventral inflection of pronotum narrow. Pubescence on lateral surface of pronotum present in pronotal trough. Anterior flange of pronotal plate distinctly protruding anteriorly, transversely strigate ( Figure 2 ). Ridges extending posteriorly from lateral margin of pronotal plate distinct but short, not extending to the dorsal margin of pronotum. Lateral pronotal carina absent. Crest of pronotal plate absent. Dorsal margin of pronotal plate (in anterior view) spatulate. Submedian pronotal depressions open laterally, deep ( Figure 2 ). Lateral margin of pronotal plate defined all the way to the dorsal margin of the pronotum. Width of pronotal plate narrow, not nearly as wide as head.

Mesoscutal surface convex, evenly curved ( Figure 1 ). Sculpture on mesoscutum absent, entire surface smooth, shiny, with sparse long hairs. Notauli absent. Median mesoscutal carina, anterior admedial lines and median mesoscutal impression all absent. Parascutal carina nearly straight.

Mesopleuron entirely smooth ( Figure 1 ). Subpleuron entirely smooth, glabrous. Lower pleuron entirely smooth, glabrous. Epicnemial carina absent. Lateroventral mesopleural carina present, marking abrupt change in slope of mesopectus. Mesopleural triangle absent. Subalar pit present, located under subalar area, not easily observed. Speculum absent. Mesopleural carina present, complete, composed of one complete, uninterrupted carina. Anterior end of mesopleural carina inserting above notch in anterior margin of mesopleuron.

Dorsal surface of scutellum distinctly striate on anterior 2/3, posterior 1/3 foveate ( Figure 2 ). Circumscutellar carina present, complete, delimiting dorsal and ventral halves of scutellum. Posterior margin of axillula marked by distinct ledge, axillula distinctly impressed. Lateroventral margin of scutellum posterior to axillula smooth. Dorso-posterior part of scutellum rounded. Transverse median carina on scutellar plate absent. Scutellar plate, in dorsal view, exposing more than half of scutellum. Scutellar fovea present, 2, distinctly margined posteriorly, smooth on bottom. Longitudinal scutellar carinae absent. Single longitudinal carina separating scutellar foveae present, short, ending at posterior margin of foveae. Posterolateral margin of scutellum rounded. Lateral bar smooth, narrow.

Metapleural-propodeal complex. Posterior impression of metepimeron absent ( Figures 2 and 2e ). Metapectal cavity anterodorsal to metacoxal base present, well defined. Anterior margin of metapectal-propodeal complex meeting mesopleuron at same level at point

corresponding to anterior end of metapleural carina. Posteroventral corner of metapleuron (in lateral view) not extended posteriorly, glabrous. Anterior impression of metepimeron absent. Posterior margin of metepimeron distinct, separating metepimeron from propodeum. Subalar area broadened anteriorly, narrowed posteriorly. Prespiracular process present, blunt, lobe-like, rough. Dorsellum absent. Anterior impression of metepisternum present. Pubescence consisting of few hairs on posterior part of metepisternum, dense hair on propodeum.

Propodeal spurs absent. Lateral propodeal carinae present, not reaching scutellum, lyre-shaped, stout. Ventral end of lateral propodeal carina reaching nucha, carinae separated from each other. Inter-propodeal carina space lightly setose, underlying surface smooth. Petiolar rim of uniform width along entire circumference. Petiolar foramen removed from metacoxae, directed posteriorly. Horizontal carina running anteriorly from lateral propodeal carina present medially, effaced laterally. Calyptra, in lateral view, rounded; in posterior view, elongate. Propodeum neck-like, drawn out posteriorly.

Legs. Pubescence posterolaterally on metacoxa, present, small, rounded, with adjacent sparse pubescence ( Figure 1 ). Microsculpture on hind coxa absent. Longitudinal ridge on the posterior surface of metatibia absent. Metafemoral tooth present, elongate, with adjacent serrate ridge posteriorly. Ratio of first metatarsal segment to remaining 4 segments 2.1:1.

Wings. Wing vein M absent ( Figure 3 ). Pubescence of fore wing present, long, dense on most of surface. Apical margin of fore wing rounded; Rs+M of fore wing defined but nebulous at point of origin from basal vein at posterior third; mesal end of Rs+M vein situated closer to anterior margin of wing, directed towards middle of basalis; vein R1 forming marginal cell completely; basal abscissa of R1 as broad as adjacent wing veins. Colouration of wing absent, entire wing hyaline. Marginal cell of fore wing membranous, similar to other wing cells. Areolet absent. Hair fringe along apical margin of fore wing present, of medium length.

Metasoma. Petiole about as long as wide ( Figures 2 ). Surface of petiole longitudinally costate, ventral keel absent. Posterior part of petiole not abruptly widened. Ventral and lateral parts of petiolar rim broad. Setal band at base of tergum 3 present, uninterrupted dorsally and ventrally ( Figures 1 and 2 ). Tergum 3 indistinct, fused with syntergum. Posterior margin of tergum 4 evenly rounded. Sternum 3 encompassed by syntergum. Sculpture on metasomal terga absent ( Figure 1 ). Syntergum present with terga 3 to 5 fused, ventral margin rounded. Peglike setae on T6 – T7 absent. Postero-ventral cavities of female metasoma T7 present, glabrous save for few, long setae. Female postero-ventral margin of T6 – T7 straight, parallel. Terebrum and hypopygium (in lateral view) straight, pointing posteriorly. Ovipositor clip present.

Male: Similar to female except for antenna with 13 flagellomeres ( Figure 2 ) with unmodified F2 ( Figure 2 ), absence of setal band at base of tergum 3 ( Figure 2 ). Metasoma, posteriorly, directly ventrally, somewhat truncate.

Variation. Body size ranges from 1.2 to 1.5 mm. Overall body colouration varies slightly from dark brown to nearly black; dorsal surface of scutellum can range from slightly striate to deeply striate, foveate at posterior end of scutellum; very faint setal tracks present on the mesoscutum of some specimens, absent in others.

Etymology. Named in honour of the late Dr John La Salle. John ’ s dedication to Hymenoptera research, and biodiversity research in general, will be greatly missed. We hope this honorific helps to keep his memory alive for years to come.

Material examined. Holotype:. ♀, CHINA, Kunming , Xiao He Research Farm, Pan Long District 25.176593°N, 102.794697°E, 2209 m above sea level (asl), 20 July 2015, from banana trap, EGWY124 (Wang Yan) USNMENT00896641; left fore and hind wings mounted on slide USNMENT01525760.

Paratypes: 1♀, CHINA, Kunming, Xiao He Research Farm , Pan Long District 25.176593°N, 102.794697°E, 2209 m asl, October 2014, from banana trap, EGWY36 (Wang Yan) USNMENT00896646 ; 1♀, CHINA, Kunming, Xiao He Research Farm , Pan Long District 25.176593°N, 102.794697°E, 2209 m asl, October 2014, from banana trap, EGWY41 (Wang Yan) USNMENT00896639 ; 1♀, CHINA, Kunming, Xiao He Research Farm , Pan Long District 25.176593°N, 102.794697°E, 2209 m asl, 20 May 2014, from banana trap, EGWY87 (Wang Yan) USNMENT00896644 ; 1♀, CHINA, Kunming, Xiao He Research Farm , Pan Long District 25.176593°N, 102.794697°E, 2209 m asl, 20 July 2015, from banana trap, EGWY103 (Wang Yan) SEM USNMENT01525765 ; 1♀, CHINA, Kunming, Xiao He Research Farm , Pan Long District 25.176593°N, 102.794697°E, 2209 m asl, 20 July 2015, from banana trap, EGWY135 (Wang Yan) USNMENT00896648 ; 1♀, CHINA, Kunming, Xiao He Research Farm , Pan Long District 25.176593°N, 102.794697°E, 2209 m asl, 20 July 2015, from banana trap, EGWY137 (Wang Yan) USNMENT00896633 ; 1♀, CHINA, Kunming, Xiao He Research Farm , Pan Long District 25.176593°N, 102.794697°E, 2209 m asl, 20 July 2015, from banana trap, EGWY129 , DS095 (Wang Yan) USNMENT01525764 ; 1♂, CHINA, Kunming, Xiao He Research Farm , Pan Long District 25.176593°N, 102.794697°E, 2209 m asl, 20 July 2015, from banana trap, EG15CZ6R BT-26 , DSZ102 (Wang Yan) USNMENT01525761 ; 1♀, CHINA, Kunming, Xiao He Research Farm , Pan Long District 25.176593°N, 102.794697°E, 2209 m asl, 20 July 2015, from banana trap, EG15CZ6R-BT , DS194 (Wang Yan) USNMENT01525762 ; 1♀, CHINA, Kunming, Xiao He Research Farm , Pan Long District 25.176593°N, 102.794697° E, 2209 m asl, 20 May 2015, from banana trap, EGWY119 (Wang Yan) USNMENT00896626 ; 1♀, CHINA, Kunming, Xiao He Research Farm , Pan Long District 25.1178°N, 102.4842°E, 23 June 2015, from banana trap, EG15CZ6RBT-19 (E. Guerrieri, M. Giorgini, K. Hoelmer) USNMENT00896625 ; 1♀, CHINA, Kunming, Xiao He Research Farm , Pan Long District 25.112378 °N, 102.481742°E, 23 June 2015, from banana trap, EG15CZ6RBT-27 (Wang Yan) USNMENT00896628 ; 1♀, CHINA, Kunming, Xiao He Research Farm , Pan Long District 25.112378°N, 102.481742°E, 23 June 2015, from banana trap, EGCZ6RBTR19-4 (Wang Yan) USNMENT00896627 ; 1♀, CHINA, Kunming, Kunming Botanical Gardens , Pan Long District , 25.145348°N, 102.741543°E, 1958 m asl, 12 July 2015, from blackberry fruits, EG15CZ5-6 (Wang Yan) USNMENT00896638 ; 1♂, CHINA, Kunming, Kunming Botanical Gardens , Pan Long District , 25.145348°N, 102.741543°E, 1958 m asl, 12 July 2015, from blackberry fruits, EG15CZ5-23 , DSZ 184 (Wang Yan) USNMENT01525763 ; 1♀, CHINA, Kunming, Kunming Botanical Gardens , Pan Long District , 25.145348°N, 102.741543°E, 1958 m asl, 12 July 2015, from blackberry fruits, EG15CZ5-32 (Wang Yan) USNMENT00896620 ; 1♀, CHINA, Kunming, Kunming Botanical Gardens , Pan Long District , 25.145348°N, 102.741543°E, 1958 m asl, 12 July 2015, from blackberry fruits, EG15CZ5-34 (Wang Yan) USNMENT00896649 ; 1♀, CHINA, Kunming, Cheng Jiang County, Long Jie Zuo Suo Cun , 24.711991°N, 102.870912° E, 2053 m asl, 24 July 2013, from banana trap, EGCZ1BTR2-2 (E. Guerrieri, M. Giorgini, K. Hoelmer) USNMENT00896624 ; 1♀, CHINA, Kunming, Cheng Jiang County, Long Jie Zuo Suo Cun , 24.711991°N, 102.870912°E, 2053 m asl, 24 July 2013, from banana trap, EGCZ1BTR2-3 (E. Guerrieri, M. Giorgini, K. Hoelmer) USNMENT00896647 ; 1♀, CHINA, Kunming, Cheng Jiang County, Fu Xian Lake , 24.506364°N, 102.860508°E, 1759 m asl, 24 July 2013, from banana trap, EGCZ2BTR4-2 (E. Guerrieri, M. Giorgini, K. Hoelmer) USNMENT00896635 ; 4♀, 6♂, CHINA, Yunnan Prov., Fumin, 25.1475°N, 102.5289°E, ex D. suzukii or D. pulchrella on Myrica rubra , 7 February 2016, Jinping Zhang ( CABI2 ) USNMENT01525940-USNMENT01525949 ; 1♀, 3♂, CHINA, Yunnan Prov., Kunming, West Mountain , 25.1475°N, 102.5289°E, ex D. suzukii on Myrica rubra , 7.II.2016, Fang Huan/Wu Hao ( CABI3 ) USNMENT01525936-USNMENT01525939.

Biology. Reared from Drosophila suzukii or D. pulchrella on Myrica rubra (CABI specimens). Other specimens were collected in the wild with banana-baited traps from May to October, with the majority in July (USNMENT00896649 emerged from blackberries). Banana traps were set up in wild vegetation in natural reserves (Kunming, Cheng Jiang County, Long Jie Zuo Suo Cun), in natural habitats surrounding orchards (Kunming, Xiao He Research Farm, Pan Long District), in blueberry crops (Kunming, Cheng Jiang County, Fu Xian Lake), and in a botanical garden (Kunming Botanical Gardens, Pan Long District).

Comments. Leptopilina lasallei possesses some unusual character states for members of Leptopilina . Using van Noort et al. (2015), male L. lasallei runs to Leptopilina ; a female specimen may also run to Leptopilina after some hesitation, but an often relied upon character, the ‘ broken ’ or ‘ interrupted ’ metasoma hairy ring character state, is not present. Instead, the hairy ring is complete in the females of L. lasallei , and this may add some confusion to diagnosing this taxon. In fact, this dimorphism is stronger than in most Eucoilinae , and interestingly, the pattern is inverted compared to other Leptopilina where the hairy ring of the female is more reduced than that of the male. This switch in dimorphism begs for clarifying observations of the behaviour of live specimens and the physiology of this trait.

Leptopilina is one of the better studied genera of Eucoilinae , with laboratory strains genetically and behaviourally studied, and a relatively large number of species that have been described or redescribed in modern times. Nevertheless, a large portion of worldwide diversity is still unaccounted for.

Leptopilina often gets confused with other small drosophilid parasitoids such as Ganaspis (Ganaspini) and Hexacola (Ganaspini) but is easily recognised by the characters that reveal its belonging in Eucoilini rather than Ganaspini : F 2 in male antennae equally or more modified (curved/excavated/elongated) than F1, glabrous and more or less oblique posteroventral corner of metapleuron. Furthermore, Leptopilina are characterised by a well-developed petiolar rim. The setal bands (‘ hairy ring ’) of the base of the metasoma are often reduced to varying extents. In a few species, female flagellomere number is reduced to 10. Most but not all species have a high, convex scutellum. These additional characters commonly occur among the genera of Ganaspini but distinguish Leptopilina from most of its closer relatives within the Eucoilini .

Within Leptopilina , two species that L. lasallei can be confused with are L. decemflagella and L. tsushimaensis , as females in both of these species have 10 flagellomeres in their antennae ( Lue et al., 2016). However, L. decemflagella and L. tsushimaensis females both have incomplete hair rings at the base of their metasoma. The striate dorsal surface of the scutellum in L. lasallei is shared with L. freyae and L. boulardi ( Allemand et al., 2002) ; again, the latter two have a metasomal hairy ring in the female which is more or less strongly reduced (incomplete or even absent); male L. lasallei have the F1 and F2 of the antennae equal in size, whereas in in L. freyae and L. boulardi , F2 is clearly longer than F1. Another useful character for distinguishing L. lasallei from L. freyae and L. boulardi , and from L. orientalis which is similar too, is the shape of the propodeal carinae: in L. lasallei , these are heavily sclerotised and thick, overall lyre-shaped; in the other species of Leptopilina that are overall similar looking, the propodeal carinae are finer, less massive and parallel sided.

Figures

Figure 1. Holotype of Leptopilina lasallei sp. nov. (USNMENT00896641). a. Lateral habitus. b. Close-up of mesosoma. c. Left fore and hind wings.

Figure 2. Scanning electron micrographs of the paratypes of Leptopilina lasallei sp. nov. (USNMENT01525765). a. Head, anterior view; I, distance from ventral margin of eye to posterior margin of malar space; II, height of eye; V, distance between inner rim of torulus to posterior clypeal margin; VI; distance between anterior ocellus and posterior rim of torulus; VII, tentorial pit; VIII, malar furrow. b. Head, dorsal view; III, width of lateral ocellus; IV, distance between lateral occeli. c. Female antenna, lateral view. d. Anterior aspect of pronotal plate, male. e. Close-up lateral aspect of metapleuron, propodeum, petiole and anterior margin of metasoma. f. Male scutellum, dorso-lateral view.

Figure 3. Male paratype. a. lateral habitus. b. Scanning electron micrograph of head and basal segments of antennae.

Figure 4. Phylogeny of Leptopilina based on Bayesian analysis of concatenated nucleotide sequences of Cytochrome Oxidase I (COI) gene ‘barcode’ region, 28S D2 and ITS2 regions. Taxa denoted by ‘DSZ’ are newly sequenced for this study; other number/letter designations are those of Genbank sequences. See Table 1 for GenBank accession numbers and references.