Megaprosternum Azevedo, 2006

Colombo, Wesley D. & Azevedo, Celso O., 2024, Revision of the strongly flattened Megaprosternum Azevedo (Hymenoptera, Bethylidae), European Journal of Taxonomy 958 (1), pp. 1-47 : 3-6

Genus Megaprosternum Azevedo, 2006

Fig. 1

Type species

Megaprosternum longiceps Azevedo, 2006 [nec Ateleopterus longiceps Ashmead, 1900 ].

Diagnosis

Body small (1.40–5.0 mm) and strongly flattened. Head, mesosoma and metasoma dark castaneous to light castaneous. Gena not visible in dorsal view. Propleuron elongated. Prosternum with probasisternum large and pentagonal.Anteromesoscutum without notaulus. Forewing without closed cells, C vein absent, Sc+R vein present, M+Cu vein absent, A vein absent, prestigmal abscissa of R1 present, 2r-rs&Rs vein absent. Hind wing with jugum fully fused to remigium. Male genitalia with harpe at least 2.0× as long as gonostipes; cuspis laminar and very wide, as wide as harpe; aedeagus subtrapezoidal; aedeagal apodeme short, not surpassing genital ring, dilated basally.

Redescription

HEAD ( Fig. 1A–D ). Median clypeal lobe surface extending back into frons, polished; antennal rim covering clypeal margin anteriorly; gena not visible in dorsal view; mandible with dorsal margin not denticulate; eye oval; ocellar triangle with anterior ocellus posterior to supraocular line; occipital carina absent; medioccipito-genal suture present.

MESOSOMA ( Fig. 1E–G ). Pronotal neck not visible in dorsal view. Pronotal lobe surface mostly flat. Propleuron elongated. Prosternum with probasisternum large and pentagonal. Anteromesoscutum without notaulus. Mesopleuron without anterior subalar pit; mesepimeral sulcus absent; mesopleural callus not evident; mesopleural epicoxal sulcus absent; lower mesopleural fovea absent; posterior oblique sulcus absent; posterior subalar pit absent; anterior mesofurcal pit oval. Metapectal-propodeal disc without transverse posterior carina; first, second and third metapostnotal carinae absent; metapostnotalpropodeal suture absent; posterior propodeal projection absent; dorsal, median and ventral metapleural pits absent; metasternal plate pentagonal. Legs with coxa longer than wide; trochanter subtriangular; femur shorter than tibia; tibia dilated apically; tarsal claw unidentate ( Fig. 1H ). Macropterous form with forewing with anterior margin incurved medially; without cells closed; C vein absent, Sc+R vein present, M+Cu vein absent, A vein absent, prestigmal abscissa of R1 present, 2r-rs&Rs vein absent ( Fig. 1I ). Hind wing with jugum fully fused to remigium.

METASOMA ( Fig. 1J–K ). Hypopygeal anteromedial apodeme absent. Male genitalia with harpe longer than gonostipes; cuspis laminar and as wide as harpe, aligned to digitus; aedeagus subtrapezoidal; aedeagal apodeme short, not surpassing genital ring, dilated basally; cupula 0.4× as long as genitalia.

Distribution

Afrotropical, Australian, Neotropical and Oriental regions.

Key for species of Megaprosternum

1. Males ................................................................................................................................................. 2

– Females ............................................................................................................................................. 5

2. Antenna with 10 flagellomeres ( Fig. 13A–B ) ................................................. M. wakawaka sp. nov.

– Antenna with 11 flagellomeres ( Gupta et al. 2017: fig. 2b) .............................................................. 3

3. Median clypeal lobe with lateral carinae converging posteriorly ( Gupta et al. 2017: fig. 2b); postocellar line almost longer than or as long as DAO ( Gupta et al. 2017: fig. 2b); propodeal spiracle on dorsal surface of the metapectal-propodeal complex ( Gupta et al. 2017: fig. 2d); hypopygium with spiculum evenly wide ( Gupta et al. 2017: fig. 3a); aedeagal apex anterior to cuspis apex ( Gupta et al. 2017: fig. 3c) ........................................................ M. cleonarovorum Gupta & Azevedo, 2017

– Median clypeal lobe with lateral carinae parallel or subparallel posteriorly ( Azevedo 2006: fig. 1); postocellar line almost shorter than DAO ( Azevedo 2006: fig. 1); propodeal spiracle on lateral surface of the metapectal-propodeal complex ( Azevedo 2006: fig. 3); hypopygium with spiculum narrowing apicad ( Azevedo 2006: fig. 12); aedeagal apex aligned to cuspis apex ( Azevedo 2006: fig. 10) ............................................................................................................................................... 4

4. Head about 1.6× as long as wide, rectangular, sides subparallel, in dorsal view ( Azevedo 2006: fig. 1); ocelli nearly touching one another ( Azevedo 2006: fig. 1) ..................................................... ......................................................................................................... M. neolongiceps Azevedo, 2018 – Head about 1.2 × as long as wide, sides convergent posteriorly, in dorsal view ( Azevedo 2006: fig. 6); posterior ocelli distant each other about 0.5× DAO ( Azevedo 2006: fig. 6) .......................... ............................................................................................................ M. pentagonal Azevedo, 2006

5. Antenna with 10 flagellomeres ( Fig. 3B ) ......................................................................................... 6

– Antenna with 11 flagellomeres ( Fig. 7A ) ......................................................................................... 9

6. Mandible with two apical teeth ............................................................................. M. bayaka sp. nov.

– Mandible with three or four apical teeth ........................................................................................... 7

7. Median clypeal lobe without lateral carinae ( Fig. 6C ) ........................................... M. kariri sp. nov.

– Median clypeal lobe with lateral carinae ( Figs 4C , 8D ) ................................................................... 8

8. Postocellar line almost as long as DAO ( Fig. 4C ); transscutal fissure conspicuous ( Fig. 4D ) .......... .......................................................................................................................... M. chamorro sp. nov.

– Postocellar line longer than DAO ( Fig. 8D ); transscutal fissure inconspicuous ( Fig. 8E ) ................. ............................................................................................................ M. longiceps ( Ashmead, 1900)

9. Apterous or micropterous forms ( Azevedo 2006: fig. 18) .............................................................. 10

– Macropterous form ( Fig. 12A ) ........................................................................................................11

10. Apterous form ..................................................................................... M. norfolcensis ( Dodd, 1924)

– Micropterous form ( Azevedo 2006: fig. 18) ...................................... M. pentagonal Azevedo, 2006

11. Head at most 1.20 × as long as wide, in dorsal view ( Fig. 2C ) ....................................................... 12

– Head at least 1.25 × as long as wide, in dorsal view ( Figs 9C , 12B ) .............................................. 14

12. Mesoscuto-scutellar foveae present ( Fig. 2D ) ............................................................ M. aka sp. nov.

– Mesoscuto-scutellar foveae absent ( Gupta et al. 2017: fig. 5f) ...................................................... 13

13. Median clypeal lobe straight ( Fig. 10B ) ............................................. M. norfolcensis ( Dodd, 1924)

– Median clypeal lobe incurved ( Gupta et al. 2017: fig. 5B) ................................................................ ....................................................................................... M. cleonarovorum Gupta & Azevedo, 2017

14. Probasisternum large with anterior margin weakly angulated ( Fig. 12D ) ......... M. samburu sp. nov.

– Probasisternum strongly large with anterior margin strongly angulated ( Fig. 9E ) ......................... 15

15. Head at least 1.50 × as long as wide with sides diverging posterad, in dorsal view ( Fig. 9C ); probasisternum with posterior margin straight ( Fig. 9E ) ...................................... M. navatu sp. nov.

– Head at most 1.40 × as long as wide with sides parallel or converging posterad, in dorsal view ( Fig. 11C ); probasisternum with posterior margin curved ( Fig. 11E ) ............................................ 16

16. Propodeal spiracle on lateral surface of the metapectal-propodeal complex ( Fig. 11A ) .................... ............................................................................................................................... M. nuaulu sp. nov.

– Propodeal spiracle on dorsal surface of the metapectal-propodeal complex ( Figs 5D , 7D ) .......... 17

17. Malar space 0.1× HE ( Fig. 5C ); epicnemium with anterior margin outcurved ( Fig. 5E ); equidistant distal hamuli; S2pa widening posterad ................................................................. M. hmong sp. nov.

– Malar space absent ( Fig. 7A ); epicnemium with anterior margin straight ( Fig. 7E ); non-equidistant distal hamuli; S2pa evenly wide ............................................................................. M. kayin sp. nov.

Figures

Fig. 1. Genus Megaprosternum, paratype, ♀ of M. navatu sp. nov. (Viti Levu, BPBM). A–D. Head. A. Dorsal view. B. Ventral view. C. Lateral view. D. Anterior view. E–G. Mesosoma. E. Dorsal view. F. Ventral view. G. Lateral view. H. Leg. I. Forewing, in dorsal view. J–K. Metasoma. J. Dorsal view. K. Ventral view. Scale bars: A–G, I = 125 μm; H, J–K = 250 μm.

Fig. 13. Megaprosternum wakawaka sp. nov., holotype, ♂ (BPBM). A–B. Habitus. A. Lateral view. B. Dorsal view.C. Head, dorsal view.D–E. Mesosoma. D. Dorsal view.E. Ventral view.F. Hypopygium, external view. Scale bars: A–B = 500 μm; C–F = 125 μm.

Fig. 3. Megaprosternum bayaka sp. nov., holotype, ♀ (SAMC, SAM-HYM P103670). A–B. Habitus. A. Lateral view. B. Dorsal view. C. Head, dorsal view. D–E. Mesosoma. D. Dorsal view. E. Ventral view. Scale bars: A = 250 μm; B–E = 125 μm.

Fig. 7. Megaprosternum kayin sp. nov., paratype, ♀ (T4398, QSBG). A–B. Habitus. A. Lateral view. B. Dorsal view. C. Head, dorsal view. D–E. Mesosoma. D. Dorsal view. E. Ventral view. Scale bars: A–B = 250 μm; C–E = 125 μm.

Fig. 6. Megaprosternum kariri sp. nov., holotype, ♀ (CZMA). A–B. Habitus. A. Lateral view. B. Dorsal view. C. Head, dorsal view. D–E. Mesosoma. D. Dorsal view. E. Ventral view. Scale bars: A–B = 500 μm; C–E = 125 μm.

Fig. 4. Megaprosternum chamorro sp. nov., paratype, ♀ (lot 891, BPBM). A–B. Habitus. A. Lateral view. B. Dorsal view. C. Head, dorsal view. D–E. Mesosoma. D. Dorsal view. E. Ventral view. Scale bars: A–B = 500 μm; C–E = 125 μm.

Fig. 8. Megaprosternum longiceps (Ashmead, 1900), syntypes, ♀♀ (USNMENT 01583000). A–C. Habitus. A. Dorsal view. B. Lateral view. C. Dorsal view of right specimen on figure A. D. Head, dorsal view. E. Labels. Scale bars: A–C = 500 μm; D = 125 μm.

Fig. 12. Megaprosternum samburu sp. nov., holotype, ♀ (ICIPE 49458). A. Habitus, lateral view. B. Head, dorsal view. C–D. Mesosoma. C. Dorsal view. D. Ventral view. Scale bars: A–B = 250 μm; C–D = 125 μm.

Fig. 2. Megaprosternum aka sp. nov., holotype, ♀ (SAMC, SAM-HYM P103665). A–B. Habitus. A. Lateral view. B. Dorsal view. C. Head, dorsal view. D–E. Mesosoma. D. Dorsal view. E. Ventral view. Scale bars: A–B = 500 μm; C–E = 125 μm.

Fig. 9. Megaprosternum navatu sp. nov., holotype, ♀ (QSBG). A–B. Habitus. A. Lateral view. B. Dorsal view. C. Head, dorsal view. D–E. Mesosoma. D. Dorsal view. E. Ventral view. Scale bars: A–B = 250 μm; C–E = 125 μm.

Fig. 10. Megaprosternum norfolcensis (Dodd, 1924). A–B, D. Non-type, ♀ (NHMUK 015663883). C. Non-type, ♀ (NHMUK 0015663884). A. Habitus, dorsal view. B–C. Head, dorsal view. D. Labels. Scale bars: A = 500 μm; B–C = 250 μm.

Fig. 11. Megaprosternum nuaulu sp. nov., holotype, ♀ (RMNH). A–B. Habitus. A. Lateral view. B. Dorsal view. C. Head, dorsal view. D–E. Mesosoma. D. Dorsal view. E. Ventral view. Scale bars: A–B = 250 μm; C–E = 125 μm.

Fig. 5.Megaprosternum hmong sp. nov., holotype, ♀ (BPBM). A–B. Habitus. A. Lateral view. B. Dorsal view. C. Head, dorsal view. D–E. Mesosoma. D. Dorsal view. E. Ventral view. Scale bars: A–B = 500 μm; C–E = 125 μm.