Revision of the genus Schoenlandella (Hymenoptera, Braconidae, Cardiochilinae) in the New World, with a potential biological control agent for a lepidopteran pest of bitter gourd (Momordica charantia L.)

Schoenlandella Cameron, 1905 is the second largest genus of Cardiochilinae. Most members are recorded from the Old World, with a small number of species in the New World. Herein, the New World species of Schoenlandella are revised based on morphological data. This work entails a description of a new species: S. montserratensis Kang, sp. nov. and potential lepidopteran host information of the new species associated with bitter gourds on the Caribbean Island of Montserrat. Schoenlandella diaphaniae (Marsh, 1986) and S. gloriosa Mercado & Wharton, 2003 are re-described, and a key to species of New World Schoenlandella is provided. The taxonomic status of Schoenlandella is discussed.


Introduction
Schoenlandella Cameron, 1905 is the second largest genus of the subfamily Cardiochilinae (Yu et al. 2016). All the members of the genus, which host data are available, are solitary endoparasitoids of exposed-feeding lepidopteran larvae such as Chrysodeixis includens (Walker, 1858) (Soybean looper; Noctuidae) and Chloridea virescens (Fabricius, 1777) (Tobacco budworm; Noctuidae). Fifty-four species have been included in the genus worldwide, and most members are recorded from the Old World, especially from the Afrotropical and Australian regions (Dangerfield et al. 1999;Mercado and Wharton 2003;Yu et al. 2016). Three species have been recorded from the New World: S. diaphaniae (Marsh, 1986), S. gloriosa Mercado & Wharton, 2003, and S. longimala (Mao, 1945).
Herein, the New World species of Schoenlandella are revised. This includes a new species description, potential host information of S. montserratensis Kang sp. nov., and a key to species of New World Schoenlandella. Previously described species of New World Schoenlandella are re-described.

Specimen information
During 2019, braconid wasps collected from a bitter gourd field in Montserrat by Dr Chris Malumphy's team (Fera Science Ltd.) were shipped to the first author (IK). Two specimens were identified as a new species of Schoenlandella based on morphological data, and potential lepidopteran hosts were identified.
Specimens were borrowed from the following institutions: The holotype and sole paratype of S. montserratensis Kang sp. nov. will be deposited in the Natural History Museum in London (NHML: London, UK).

Morphological analysis
A Leica MZ75 stereomicroscope was used to examine specimens. Morphological terminology used in this review are mostly based on Dangerfield et al. (1999) and Sharkey and Wharton (1997), supplemented by terms on the Hymenoptera Anatomy Consortium website (http://portal.hymao.org/projects/32/public/ontology/, accessed in September 2020). Terms for surface sculpture follow Harris (1979). The following acronyms are used for morphological terms: T1: first metasomal tergite; T2: second metasomal tergite; T3: third metasomal tergite; T4: forth metasomal tergite; T6: sixth metasomal tergite. Color images were taken with a Visionary Digital BK Plus imaging system (Dun, Inc.) equipped with a Canon EOS 5DS DSLR camera. Multiple images were stacked using Zerene Stacker v.1.04 (Zerene Systems LLC.) and edited in Adobe Photoshop CS 6 and Photoshop CC (Adobe Systems, Inc). Body parts were measured also via Adobe Photoshop CS 6 and Photoshop CC. Each number in parentheses in species descriptions indicate 0.01× the actual size of each body part. The unit of length is mm. For example, 12 and 123 in parentheses (12:123) indicate 0.12 mm and 1.23 mm, respectively. The distribution map of the new species was generated using QGIS 3.10.0 (QGIS Development Team 2019). The Google terrain map was downloaded using Quick-MapServices plugin.

Diagnosis (based on Dangerfield et al. (1999) with additions and modifications).
Diagnostic characters of Schoenlandella were described in Dangerfield et al. (1999), based mostly on Old World species. The following are diagnostic features based on both Old World and New World members. Members of Schoenlandella can be distinguished from species of other cardiochiline genera by the following characters: Head: possessing 32-44-segmented antenna; densely setose eye (Figs 2C, 4C); two clypeal tubercles with sharp or smooth apical margin (Fig.  1C); short to elongate malar space; bidentate mandible; six-segmented maxillary palpus; four-segmented labial palpus; absence of occipital carina; elongate galea, at least as long as malar space in lateral view (Note: narrower than galeae of members of Cardiochiles   Marsh, 1986(Marsh 1986) Schoenlandella diaphaniae (Marsh, 1986)  Description. Marsh (1986) described color of the species and some morphological characters in his species description. Here, the species is re-described based on a specimen collected in Trinidad and Tobago.
Description. Modified from Mercado and Wharton (2003), including additional characters.
Color. See Mercado and Wharton (2003). Melanic areas of the Costa Rican specimen (female) and Mexican specimens are slightly darker than specimens collected in Honduras.

Diagnosis (based on images of the holotype on the NMNH website).
Body mostly black except for legs. Malar space shorter than basal width of mandible. Mouthparts moderately elongated. Scutellar sulcus with six crenulae. Lateral side of scutellum mostly rugulose. Pronotum medially rugose, with median areola anteriorly angled. Forewing entirely infuscate; stigma entirely melanic; 3r vein absent; 1a present as a nebulous vein.
Etymology. This species is named after the collecting site, "Montserrat", a volcanic Caribbean Island.
Host. Unknown but see details in the following discussion section. Distribution. Schoenlandella montserratensis sp. nov. is only known from Montserrat (Fig. 3).

Taxonomic status of Schoenlandella and character discussion
The validity of the taxonomic status of Schoenlandella Cameron has fluctuated several times before the current work. Dangerfield et al. (1999) indicated that species of Schoenlandella could be easily distinguished from all other cardiochiline genera based on the following five characters: conspicuously setose eyes; long and deeply bilobed glossa; elongate blade-like galea; presence of spectral 3r of forewing (if absent, members of the genus have relatively short mouthparts); evenly sclerotized hypopygium (if a median longitudinal fold is present, the surface is not membranous). The genus was resolved as a monophyletic group in the phylogeny in Dangerfield et al. (1999) based on morphological data. However, Mercado and Wharton (2003) and Papp (2014) indicated difficulty in distinguishing members of Schoenlandella from those of Cardiochiles Nees. Dangerfield et al. (1999) and Mercado and Wharton (2003) retained Schoenlandella as a valid genus, and the latter author subsumed the genus into Cardiochiles as a subgenus. Edmardash et al. (2018) treated Schoenlandella as a valid genus.
Only one study partially indicated genus-level relationships of Cardiochilinae. Murphy et al. (2008) presented three phylogenies based on seven genes. Even though the phylogenies focused on subfamily-level relationships of microgastroid subfamilies, genus-level relationships of five cardiochiline genera were included. Cardiochiles and Schoenlandella were resolved as polyphyletic in a clade with a rare Australian genus, Gwenia Dangerfield, Austin & Whitfield in their Maximum Parsimony phylogeny. However, the other two phylogenies resulting from Maximum Likelihood and Bayesian phylogenetic analyses using the same molecular data indicated that members of each genus were well-clustered even though they were recovered as paraphyletic. It should be noted that Murphy et al. (2008) treated C. minutus (Cresson) as a member of Schoenlandella and indicated Cardiochiles and Schoenlandella were polyphyletic. We treat S. minuta in Murphy et al. (2008) as C. minutus (Cresson) since Mercado and Wharton (2003) transferred the species to Cardiochiles.
In the current work, we examined specimens of both New World and Old World Schoenlandella species. Old World members mostly possess and share the five diagnostic characters defined by Dangerfield et al. (1999). We confirmed that specimens of S. montserratensis sp. nov. collected in Montserrat are the first New World species having the five diagnostic characters. Of the other three New World species, specimens of S. diaphaniae and S. gloriosa were examined, and morphological characters of S. longimala were confirmed based on descriptions of Mao (1945) and images of the holotype on the NMNH website (https://collections.nmnh.si.edu/search/ento/, accessed September 2020). All New World species have dense eye setae consistent with Old World members. Dangerfield et al. (1999) indicated that most Schoenlandella members possess elongate mouthparts. Tucker et al. (2012) discussed two hypotheses regarding the elongation of mouthparts of the Afrotropical agathidine genus Camptothlipsis Enderlein and preferred the hypothesis that the members with elongate mouthparts are specialized nectar feeders, dependent on flowers that their host caterpillars feed on. This has been confirmed in the case of Agathis malvacearum Latreille (Juhala 1967). Most other cardiochilines as well as members of Heteropteron Brullé, which was resolved as the most ancestral cardiochiline genus (Dangerfield et al. 1999;Murphy et al. 2008) possess short mouthparts. The elongate mouthparts most likely evolved independently in Schoenlandella. Some Old World members and the three New World species in the current work possess relatively shorter mouthparts than most Schoenlandella species (but narrower and longer than the typical mouthparts of Cardiochiles). This seems to be a secondary loss due to environmental changes like host flower traits. In addition, IK confirmed that females of S. diaphaniae and S. gloriosa do not possess the median membranous fold or area in the hypopygium. The hypopygial character of S. longimala could not be confirmed because the holotype is male. Additionally, most Schoenlandella members possess an angled RS vein in the forewing, which is not present in Cardiochiles. They also have relatively longer second submarginal cells than members of Cardiochiles. Despite the contradictory opinions of Papp (2014) and Murphy et al. (2008), we treat Schoenlandella as a valid genus as in Dangerfield (1999) and Mercado and Wharton (2003) and place the New World species in the genus. IK is conducting molecular analysis to generate a phylogeny to determine genus-level relationships of cardiochilines based on a larger taxon sample than previous research. We expect that the phylogeny will help resolve the taxonomic issue in the near future and predict that Schoenlandella will be confirmed as a valid genus with support of shared morphological characters such as elongate mouthparts, angled Rs vein and elongated submarginal cell of the forewing, and evenly sclerotized surface of the hypopygium.
Potential host information of S. montserratensis sp. nov.
Female adults of S. montserratensis sp. nov. were collected in a bitter gourd field in Montserrat in 2019. Four potential lepidopteran host species were collected in the same location in the same period: Diaphania hyalinata (L., 1767) (Melonworm moth; Crambidae); Plutella xylostella (L. 1758) (Diamondback moth; Plutellidae); Calpodes ethlius (Larger canna leafroller; Hesperiidae), and unidentified bagworm (Psychidae) (Dr Chris Malumphy pers. comm.). Among these species, the melonworm moth caterpillars were the most serious pests in the field. Because other Schoenlandella species chiefly attack caterpillars of Crambidae and Noctuidae (Ta-ble 1), the melonworm moth caterpillar may be the preferred host of S. montserratensis sp. nov. If females of the new species are host specific and attack the melonworm moth caterpillars as expected, females of S. montserratensis sp. nov. should be developed as effective biological control agents for the melonworm moth. Detailed biology of S. montserratensis sp. nov. and its host range will need to be confirmed in further investigations (i.e., rearing caterpillars and collecting parasitoids of the host caterpillars). Future studies should investigate the effectiveness of S. montserratensis sp. nov. to parasitize the melonworm moth and determine its potential as a biological control agent against melonworm moth.