Megaprosternum cleonarovorum Gupta & Azevedo

Gupta, Ankita, Rajeshwari, S. K. & Azevedo, Celso O., 2017, Biology and description of Megaprosternum cleonarovorum sp. nov. (Hymenoptera: Bethylidae) a gregarious larval ectoparasitoid of Cleonaria bicolor Thomson (Coleoptera: Cerambycidae) from India, Zootaxa 4237 (1) : -

publication ID	https://doi.org/ 10.11646/zootaxa.4237.1.4
publication LSID	lsid:zoobank.org:pub:8E3AA8C7-B7B2-4AAE-BF12-D430138E5B61
DOI	https://doi.org/10.5281/zenodo.6016672
persistent identifier	https://treatment.plazi.org/id/03C187BF-BF07-C862-E5D6-FDB9FDDC4DDD
treatment provided by	Plazi
scientific name	Megaprosternum cleonarovorum Gupta & Azevedo
status	sp. nov.

Treatment

Megaprosternum cleonarovorum Gupta & Azevedo sp. nov.

Figs 1–5 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5

Type material. Holotype ♂, INDIA, Karnataka, Bangalore, Hebbal , 13.03°N 77.59°E, 23.viii.2016, ex: Cleonaria bicolor Thomson ( Coleoptera , Cerambycidae ) on the host plant Ixora coccinea L., coll. S.K. Rajeshwari, code - NBAIR / Beth / Mega /23816A ( NBAIR). GoogleMaps

Allotype ♀ (same data as the holotype), code - NBAIR /Beth/Mega/23816 B ( NBAIR).

Paratypes: 4♀, 1♂ 20.vii.2016, same collection locality as holotype, codes - NBAIR/Beth/Mega/20716B (NBAIR); 5♀, 1♂, 17.ix.2016, same collection locality as holotype; codes - NBAIR/Beth/Mega/17916B (NBAIR).

Etymology. The specific epithet is derived from its host.

Distribution. India, Karnataka.

Diagnosis. Male. Head in frontal view about 1.24× (0.41: 0.33) as long as wide in holotype and 1.34× (0.47: 0.35) in paratype, with sides convergent posteriorly. Ocelli not touching one another. Female. Body length 2.99‒3.19 mm, head 1.31× as long as wide in frontal view.

Description. Male ( Figs 1 View FIGURE 1 ¯3). Length ( Fig. 1 View FIGURE 1 A, B). Body 2.37‒2.48 mm, fore wing 1.32‒1.40 mm. Body very flat, head 0.22× as high as long in lateral view. Colour ( Fig. 1 View FIGURE 1 A, B). Body black except as follows: mandible apex dark castaneous; antenna from dark castaneous to almost black; palpi dark castaneous; legs almost black except tibiae and tarsi dark castaneous; wings hyaline, central area of fore wing slightly infuscated, wing venation dark castaneous.

Head ( Fig. 2 View FIGURE 2 A–C). Head varying from subrectangular ( Fig. 2 View FIGURE 2 A), subelliptical ( Fig. 2 View FIGURE 2 B) to subquadrate ( Fig. 2 View FIGURE 2 C). Mandible with three distal, sharp teeth. Clypeus extremely short, apical margin slightly incurved, surface concave, extending back into frons for about half length of eye, slender and polished with pair of lateral carinae which separate it from frons. Antenna long, almost reaching tegula; first four antennomeres in ratio of about 12:7:4:6; scape curved medially, antennal pubescence short and dense. Eye ovoid, setose, placed laterally, very close to mandible; malar space short. Frons coriaceous with reticulations. WH 0.8× LH in frontal view, WF 0.6× WH, WF 1.11× HE, OOL 2.1× WOT; frontal angle of ocellar triangle acute, posterior ocelli distant from vertex crest by 0.9‒1.1× DAO. Vertex varying from almost straight for short ( Fig. 2 View FIGURE 2 A) or long distance ( Fig. 2 View FIGURE 2 C) to broadly convex ( Fig. 2 View FIGURE 2 B), corners always rounded, temples slightly diverging anteriorly. VOL 1.5× HE. Occipital carina absent.

Mesosoma ( Fig. 2 View FIGURE 2 D). Mesoscutum about 0.7× long as pronotal disc, separated from mesoscutellum by very fine and shallow line. Notauli and parapsidal furrows absent. Mesoscutellum with shallow reticulation, without groove or pits; posterior margin slightly curved posteriorly. Metanotum reduced. Metapectal-propodeal complex with posterior half distinctly narrower than anterior half; median length 0.91–1.1× median width, without anterior and posterior transverse carinae or median and lateral carinae; dorsal surface coriaceous, stronger posteriorly; propodeal spiracles located at mid-length of disc level, entirely directed outward, declivity reduced. Prosternum pentagonal , width 2.7× median length of propleuron ( Fig. 2 View FIGURE 2 C). Mesopleuron coriaceous, central pit not prominent. Profemur 3.1× long as wide; tibiae not spinose, but sparsely setose; tarsal claws simple. Wings slender ( Fig. 1 View FIGURE 1 A, B), fore wing with only subcostal vein and small stigma ( Fig. 2 View FIGURE 2 E), subcostal vein short, only 0.2× as long as fore wing.

Metasoma ( Fig. 2 View FIGURE 2 F) elongate, about 1.5× as long as mesosoma; weakly coriaceous; setae long, especially on apical segments. Hypopygium ( Fig. 3 View FIGURE 3 A) elongate, medial stalk about 0.6× as long as plate, only slightly narrowing apically, lateral stalk absent, posterior margin almost straight. Genitalia ( Fig. 3 View FIGURE 3 B, C). Paramere elongate, much longer than basiparamere, narrower below apex, apex rounded. Cuspis laminar, large, wide, apex truncate with corners narrowly rounded, lateral margins parallel, as high as two thirds of paramere. Digitus with apex directed outward, as high as cuspis. Aedeagus slightly wider medially, its apex slightly lower than cuspis apex, with pair of rounded apical lobes, apodeme short, not dilated basally. Basal ring ( Fig. 3 View FIGURE 3 D) large, about 0.4× as long as genitalia.

Female ( Figs 4 View FIGURE 4 , 5 View FIGURE 5 ). Length ( Fig. 4 View FIGURE 4 A, B). Body 2.99‒3.19 mm; fore wing 1.56 mm. Body very flat, head 1.31× as long as wide in frontal view and 0.26× as high as long in lateral view ( Fig. 5 View FIGURE 5 A). Colour ( Fig. 5 View FIGURE 5 A–H). Body black except as follows: antenna from dark castaneous to almost black; mandible reddish castaneous; palpi dark castaneous; legs almost black except tibiae and tarsi dark castaneous; wings hyaline but central area of fore wing slightly infuscated and wing venation dark castaneous.

Head ( Figs 5 View FIGURE 5 A–C). Head subrectangular ( Fig. 5 View FIGURE 5 C). Clypeus retracted, apical margin incurved, extending back into frons for less than half length of eye, elongate, subparallel and polished, without median carina. Antenna long, almost reaching tegula; first four antennomeres in ratio of about 17: 5: 3: 5; scape flattened medially; segment XI slightly longer than wide; antennal pubescence subappressed, with some suberect, outstanding setae. Eye ovoid, setose, placed laterally, very close to mandible; malar space short. Frons coriaceous. WH 0.68× LH, WF 0.66× WH, WF 1.3× HE, OOL 3.1× WOT; frontal angle of ocellar triangle acute, posterior ocelli distant from vertex crest by 0.9× DAO. Vertex almost straight, corners broadly rounded, temples slightly diverging anteriorly. VOL 1.83× HE. Occipital carina absent.

Mesosoma ( Fig. 5 View FIGURE 5 F). Mesoscutum 0.56× as long as pronotal disc, separated from mesoscutellum by distinct line. Notauli and parapsidal furrows absent. Mesoscutellum transverse, without groove or pits; posterior margin slightly curved posteriorly. Metanotum completely absent dorsally. Metapectal-propodeal complex with median length 0.95‒1.1× median width, without anterior and posterior transverse carinae or median carina, and with lateral carinae very weak, converging in declivity and reach propodeal foramen; dorsal surface coriaceous, stronger posteriorly; propodeal spiracles located at mid-length of disc at middle leg foramen level, entirely directed outward. Prosternum pentagonal , width 2.75× median length of propleuron. Mesopleuron coriaceous. Tegula present, 0.07 mm long. Profemur enlarged, 2.17× long as wide; tibiae not spinose; tarsal claws simple. Wings slender ( Fig. 4 View FIGURE 4 A, B), fore wing with only subcostal vein and small stigma ( Fig. 5 View FIGURE 5 G), subcostal vein short, only 0.2× as long as fore wing.

Metasoma ( Fig. 5 View FIGURE 5 H). Elongate, about 1.5× as long as mesosoma; weakly coriaceous; setae long, particularly on apical segments.

Host ( Fig. 7 View FIGURE 7 A–D). Megaprosternum cleonarovorum is a gregarious larval ectoparasitoid of Cleonaria bicolor Thomson ( Coleoptera , Cerambycidae ) on the host plant Ixora coccinea L. ( Fig. 7 View FIGURE 7 E).

Biology. Host biology. An adult of C. bicolor damages the leaves of the host plant by making elongate incisions with its mandibles on either side of the midrib ( Fig. 6 View FIGURE 6 C, 7D) and eggs are laid in the intermodal region of the stem where the grubs form galleries ( Fig. 7 View FIGURE 7 A). The galleries formed by the grub with the parasitized stages and cocoons measure 2.76± 0.35 mm in width, and the stem thickness measures 2.6¯ 2.7 mm in diameter.

The grubs are legless and cream yellow in colour. They pupate inside the burrow and the pupae are light yellow in colour. In August, several parasitized grubs were collected. In September, the pre-pupal stage along with the pupal stage was noticed, indicating a very brief pupal period after larval diapause followed by adult emergence in late September and October.

The incisions on leaves caused by adults is the first indication of infestation followed by yellowing of branches and exudation of frass through cracks on the bark as mentioned by Prathapan et al. (2010). In our study, the pest caused severe leaf damage symptoms ( Fig. 6 View FIGURE 6 C) and severely curtailed plant growth ( Fig. 6 View FIGURE 6 D); later the entire plant collapsed leading to complete loss of the plantation.

Parasitoid biology ( Figs 8 View FIGURE 8 A–H). The eggs of M. cleonarovorum are oval and off white in colour, and measure 0.40± 0.02 mm long and 0.17± 0.01 mm wide. They are often arranged on the lateral sides and towards the posterior region of the host grub. This preferred site for oviposition is unlike the ventral abdominal preference shown by Cephalonomia gallicola (Ashmead) as indicated by Itoh (1980). The average number of eggs per grub was 38±9.96. They hatch 4¯5 days after oviposition. On average, 68¯77.4% emergence of wasps was noticed in comparison to the total number of eggs laid per grub. The larvae are gregarious and feed for 3¯4 days. The early instars measure 0.85± 0.07 mm; mid instars measure 1.53± 1.26 mm and attain a length of 2.26± 0.25 mm before spinning their cocoons in a mass within the galleries of the host grubs. The cocoons are 3.01± 0.22 mm long and 0.97± 0.11 mm wide, and range in colour from white when freshly laid to buff brown after two days. The cocoon stage lasts about 14¯15 days; a single female was observed guarding the unhatched cocoons (directly collected from field). Adults within the host galleries lived for 12¯17 days; adults fed with 50% honey lived for 12¯15 days in glass test tubes and adults without any feed neither residing in galleries nor feeding on honey lived for 4¯5 days. The average life span from oviposition to adult longevity is 37±2 days.

The field collected cocoon masses produced 21.83±4.79 cocoons/brood and the adult emergence was 18.17±5.91 wasps/cocoon mass. The laboratory reared broods produced 31.5±11.59 cocoons/brood and the adult emergence was 22.5±11.9 wasps/cocoon mass. We observed a highly male-biased mean sex ratio and on an average 1¯ 3 males emerged per brood, unlike the solitary male/brood as noticed by Morgan & Cook (1994).

The first female after emergence was noticed probing other cocoons facilitating their emergence. After emergence the wasps showed restlessness in behavior and took shelter on and off in the empty cocoon cases. Mating couples could be seen within 2¯3 minutes post emergence. Later the aggregation of females along with male/males, accompanied by mating, was noticed hidden in the crevices of the stems. In all the field collected cocoon masses a single female was observed guarding the cocoons ( Fig. 8 View FIGURE 8 H).

The parasitized grubs and cocoons were observed wherever the stem thickness measured 2.6¯ 2.7 mm in diameter. The thicker stems carried the prepupal, pupal and adult stages of hosts with large emergence holes on stems associated with frass ( Figs 6 View FIGURE 6 A, B).