Paraxenos Saunders, 1872

Benda, Daniel, Pohl, Hans, Nakase, Yuta, Beutel, Rolf & Straka, Jakub, 2023, A new species of the genus Paraxenos Saunders, 1872 (Strepsiptera: Xenidae) from Bembix digger wasps (Hymenoptera: Bembicidae) and a redescription of Paraxenos hungaricus (Székessy, 1955), European Journal of Taxonomy 885 (1), pp. 134-155 : 150-151

Key to species of Paraxenos Saunders, 1872 parasitizing digger wasps of the genus Bembix Fabricius, 1775 based on female cephalothorax (modified and extended from Kifune & Hirashima 1987)

1. Old World distribution ...................................................................................................................... 2

– Australian distribution ...................................................................................................................... 4

2. Mandible completely enclosed in mandibular capsule (md, Figs 2A , 6C ) ....................................... 3

– Mandible projecting beyond anterior edge of head capsule (md, Fig. 7 ); host: Bembix orientalis (Handlirsch, 1893) ; Sri Lanka............................. Paraxenos krombeini Kifune & Hirashima, 1987

3. Maxilla anteriorly directed, maxillary base ~ 2–3× as wide as distal part of maxilla (mxb, mx, Fig. 6E–F ); labial area between maxillae distinctly wider than long in midline (lba, Fig. 6C ); shiny area near submaxillary groove without conspicuous dark papillae on lateral cephalic extensions (lehc, Fig. 3C ; lehc, smxg, Fig. 6A ); dark lateral region of abdominal segment I below spiracles distinctly contrasting to pale coloration of thorax on dorsal side (asI, Fig. 3D ); hosts: Bembix oculata Panzer, 1801 , Bembix rostrata (Linnaeus, 1758) , Bembix sp. ; distribution: widespread in the Palearctic Region .............................................................. Paraxenos hungaricus ( Székessy, 1955)

– Maxilla anteromedially directed, maxillary base ~ 3× as wide as distal part (mxb, mx, Fig. 2A ); labial area between maxillae slightly wider than long (lba, Fig. 2A ); lateral cephalic extensions completely dull on ventral side (lehc, Fig. 2A ), covered by conspicuous, densely arranged dark papillae; lateral region of abdominal segment I below spiracles only slightly darker on dorsal side (asI, Fig. 1D ); host: Bembix kohli Morice, 1897 ; distribution: United Arab Emirates....................... ............................................................................................................... Paraxenos arabicus sp. nov.

4. Spiracles situated at about midlength of cephalothorax; maximum width of cephalothorax ca 1.8 mm; host: Bembix atrifrons F. Smith, 1856 ; distribution: Western Australia ............................................. ........................................................................... Paraxenos occidentalis Kifune & Hirashima, 1987

– Spiracles situated at about basal third of cephalothorax; maximum width of cephalothorax ca 1.6 mm; lateral margins of cephalothorax evenly curved; host: Bembix musca Handlirsch, 1894 ; distribution: Australia (Queensland) ................................... Paraxenos australiensis Kifune & Hirashima, 1987

Key to species of Paraxenos Saunders, 1872 parasitizing digger wasps of the genus Bembix Fabricius, 1775 based on male cephalotheca

Cephalotheca of Paraxenos australiensis , P. krombeini , and P. occidentalis unknown.

1. Clypeal lobe distinctly wider than length of mandible (cll, Fig. 4E ); distance between mandibles very distinctly exceeding mandibular length; maxilla at base ~ 2× as wide as mandible (mx, Fig. 4A, E ); clypeus (clypeal lobe) prominent in lateral view, but blunt anteriorly (cl, Fig. 4B ); pale stripe between compound eye and mandibular base as wide as diameter of compound eye; hosts: Bembix oculata Panzer, 1801 , Bembix rostrata (Linnaeus, 1758) , Bembix sp. ; distribution: widespread in the Palearctic Region ............................................................... Paraxenos hungaricus ( Székessy, 1955)

– Clypeal lobe ~ as wide as mandibular length (cll, Fig. 4F ); maxilla at base ~ 1.5× as wide as mandible (mx, Figs 2C , 4F ); clypeus (clypeal lobe) not prominent in lateral view (cl, Fig. 2D ); pale stripe between compound eye and mandibular base ~ 2× as wide as diameter of compound eye; host: Bembix kohli Morice, 1897 ; distribution: United Arab Emirates......... Paraxenos arabicus sp. nov.

Figures

Fig. 2. Paraxenos arabicus Benda & Straka sp. nov. A–B. Female (NMPC), cephalothorax. C–D. Male (NMPC), cephalotheca. A. Detail of ventral side. B. Detail of dorsal side. C. Frontal view. D. Lateral view. Abbreviations: a = vestigial antenna; cl = clypeus; cll = clypeal lobe; coe = compound eye; dlf = dorsal labral field of labral area; fr = frontal region; fssf = furrow of supra-antennal sensillary field; gn = gena; lba = labial area; lehc = lateral extension of head capsule (lateral cephalic extension); md = mandible; mx = vestige of maxilla; mxb = maxillary base; mxp = vestige of maxillary palp; os = mouth opening; pom = postmentum; prm = praementum; pst = prosternum (prosternal extension); pstp = prosternal papilla; sbhp = segmental border between head and prothorax; smxg = submaxillary groove; ssf = supra-antennal sensillary field; vlf = ventral labral field of labral area.

Fig. 6. Paraxenos hungaricus (Székessy, 1955), ♀ (OLML), cephalothorax, SEM micrographs. A. Anterior part of cephalothorax, ventral side. B. Anterior part of cephalothorax, dorsal side. C. Mouthparts, ventral side. D. Detail of anterior border of cephalothorax, ventral side. E. Right mandible and maxilla, ventral side. F. Left mandible and maxilla, ventral side. Abbreviations: cl = clypeus; cls = clypeal sensillum; dlf = dorsal labral field of labral area; lba = labial area; ls = labral seta in cavity (spine-shaped sensillum); md = mandible; mx = vestige of maxilla; mxb = maxillary base; mxs = maxillary sensillum; sb cl = segmental border between clypeus and labrum; smxg = submaxillary groove; vlf = ventral labral field of labral area.

Fig. 7.Paraxenos krombeini Kifune &Hirashima, 1987,holotype, ♀ (KUMC), cephalothorax.A.Anterior part of cephalothorax, ventral side. B. Anterior part of cephalothorax, dorsal side. Abbreviations: lba = labial area; md = mandible; mx = vestige of maxilla.

Fig. 3. Paraxenos hungaricus(Székessy, 1955), host, female cephalothorax (OLML). A. Bembix rostrata (Linnaeus, 1758) stylopized by P. hungaricus, lateral view. B. Detail of host abdomen of B. rostrata, with adult female. C. P. hungaricus from B. rostrata, ventral side of cephalothorax. D. P. hungaricus from B. rostrata, dorsal side of cephalothorax. Abbreviations: asI = abdominal segment I; cll = clypeal lobe; csI = constriction of abdominal segment I; lehc = lateral extension of head capsule; mst = mesosternum; mtst = metasternum; pst = prosternum (prosternal extension); sb ma = segmental border between metathorax and abdomen; sb = segmental border between mesothorax and metathorax; sb = mm pm segmental border between prothorax and mesothorax; sp = spiracle.

Fig. 1. Paraxenos arabicus Benda & Straka sp. nov., host, male puparium, female cephalothorax. A. Bembix kohli Morice, 1897 stylopized by P. arabicus sp. nov., lateral view. B. Detail of host abdomen of B. kohli, with male puparium. C–D. Holotype of P. arabicus sp. nov., ♀ (NMPC) from B. kohli. C. Ventral side of cephalothorax. D. Dorsal side of cephalothorax. Abbreviations: asI = abdominal segment I; cll = clypeal lobe; csI = constriction of abdominal segment I; lehc = lateral extension of head capsule; mst = mesosternum; mtst = metasternum; pst = prosternum (prosternal extension); sb ma = segmental border between metathorax and abdomen; sb mm = segmental border between mesothorax and metathorax; sb pm = segmental border between prothorax and mesothorax; sp = spiracle.

Fig. 4. A–E. Paraxenos hungaricus (Székessy, 1955), ♂ (NMPC). F. Paraxenos arabicus Benda & Straka sp. nov., ♂ (NMPC). A. Frontal view of cephalotheca). B. Lateral view of cephalotheca. C. Ventral view of anterior part of the puparium. D. Dorsal view of anterior part of the puparium. E. Detail of cephalotheca, frontal view. F. Detail of cephalotheca, frontal view. Abbreviations: a = vestigial antenna; asI = abdominal segment I; cl = clypeus; cll = clypeal lobe; coe = compound eye; csI = constriction of abdominal segment I; dlf = dorsal labral field of labral area; fr = frontal region (frons); fssf = furrow of supra-antennal sensillary field; gn = gena; hyp = hypopharynx; lgI = foreleg; lgII = middle leg; lgIII = hindleg; md = mandible; mst = mesosternum; mtst = metasternum; mx = maxilla; mxp = vestige of maxillary palp; pom = postmentum; prm = praementum; pst = prosternum; sb hp = segmental border between head and prothorax; sb = segmental border between metathorax and ma abdomen; sb = segmental border between mesothorax and metathorax; sbpm = segmental border mm between prothorax and mesothorax; ssf = supra-antennal sensillary field; vlf = ventral labral field of labral area; wbI = wing buds I; wbII = wing buds II.