Eupathocera Pierce, 1908, stat. res.

Benda, Daniel, Pohl, Hans, Nakase, Yuta, Beutel, Rolf & Straka, Jakub, 2022, A generic classification of Xenidae (Strepsiptera) based on the morphology of the female cephalothorax and male cephalotheca with a preliminary checklist of species, ZooKeys 1093, pp. 1-134 : 1

Eupathocera Pierce, 1908, stat. res.

Eupathocera Pierce, 1908: 79. Type species: Eupathocera lugubris Pierce, 1908, by original designation.

Pseudoxenos Saunders, 1872 (partim!) (synonymy proposed by Bohart 1937: 133).

Paraxenos Saunders, 1872 (partim!) (synonymy proposed by Kinzelbach 1971b: 162).

Homilops Pierce, 1908: 80 (syn. nov.). Type species: Xenos westwoodii Templeton, 1838, by subsequent designation.

Sceliphronechthrus Pierce, 1909: 141 (syn. nov.). Type species: Sceliphronechthrus fasciati Pierce, 1909, by original designation.

Ophthalmochlus Pierce, 1909: 142 (syn. nov.). Type species: Ophthalmochlus duryi Pierce, 1909, by original designation.

Ophthalmochlus (Isodontiphila) Pierce, 1919: 465 (syn. nov.). Type species: Ophthalmochlus auripedis Pierce, 1911.

Diagnosis of female cephalothorax.

Differing from its sister genus Leionotoxenos by the shape of the periantennal area and the microstructure of the frontal area. Periantennal area expanded, sometimes raised, smooth (Fig. 29C ). Distance between antennal area and supra-antennal sensillary field relatively large. Frontal region smooth or indistinctly wrinkled (Fig. 30B ). Prosternum of most species of Eupathocera distinctly elevated above head medially and laterally, but apparently flat in Leionotoxenos (Fig. 29A ). Rudiments of antennal torulus usually preserved (Fig. 29D ). Sensilla restricted to clypeal lobe, not extended to ventral side of clypeal area. Mandible not protruding from capsule. In contrast to Paragioxenos , head and prothorax ventrally delimited by birth opening medially and by suture laterally.

Description of female cephalothorax.

Shape and coloration. Compact, variable in shape, longer than wide to nearly as long as wide. Abdominal segment I sometimes protruding laterally, forming corner below spiracles (Fig. 28D ). Very variable in size, length 1.02-2.47 mm, maximum width 0.88-2.5 mm. Anterior head margin evenly rounded or slightly protruding. Thorax slightly widening posteriorly. Coloration variable, with mostly dark or light brown pattern, but also patterns of multiple brown shades.

Head capsule. Ca. ¼ ~ ⅖ as long as entire cephalothorax including lateral cephalic extensions. Coloration rather pale to dark or forming specific patterns. Clypeal area well defined or not well delimited from labral area, with indistinct or slightly protruding clypeal lobe. Surface varying from wrinkled, lamellar, with scarcely visible sensilla, to completely smooth with distinctly exposed sensilla. Number of clypeal sensilla 20-80 or even more. Border between clypeal and frontal region clearly recognizable or indistinct but still present. Frontal region smooth or indistinctly wrinkled (Fig. 30B ). Segmental border between head and prothorax distinct or only faintly recognizable on dorsal side.

Supra-antennal sensillary field. Smooth or slightly wrinkled, with dispersed sensilla (Fig. 29D ). Not distinctly delimited by furrow medially, but border marked by different surface structure of supra-antennal sensillary field and smooth frontal region (Fig. 30B ).

Antenna. Preserved as more or less clearly defined area. Antennal torulus usually reduced, preserved as interrupted furrow (Fig. 29D ). Periantennal area expanded, sometimes raised, smooth (Fig. 29C ). Distance between antennal area and supra-antennal sensillary field relatively large.

Labrum. Ventral field wider than long, elliptic to nearly circular. Dorsal labral field slightly arcuate, at least 4 × wider than long in midline. Setae on dorsal field conspicuous, ~ 10-22.

Mandible. Anteromedially directed at an angle of 30-55°, enclosed in mandibular capsule. Mandibular bulge more or less distinctly raised, with ~ 5 indistinct sensilla. Cuticle of mandible smooth with longitudinal grooves or sculptured. Mandibular tooth narrow or slightly widened, with or without spines.

Maxilla. Reduced and not distinctly protruding, not projecting beyond mandible anteriorly. Partially fused to labial area, both regions often not clearly separated. Cuticle wrinkled or reticulated, in some cases with smooth areas. Vestige of palp inconspicuous, forming small bulge, sometimes very indistinct, located anteriorly or medially on ventral side of maxilla. Submaxillary groove indistinctly produced posteriorly to maxillary base.

Labium. Labial area more or less distinctly recognizable between maxillae, flat, longer than wide in midline or as long as wide. Anteriorly delimited by mouth opening, posteriorly by birth opening. Cuticular surface smooth or slightly reticulated.

Mouth opening. More or less arcuate, sclerotized along margin.

Thorax and abdominal segment I. Pro-mesothoracic and meso-metathoracic borders variable, distinct or indistinct, usually indicated by mesal furrows, often combined with pigmented stripes. Border between metathorax and abdomen usually marked by change in cuticular surface structure or pigmentation. Cuticle of thoracic segments reticulate on ventral side, often with scattered small, pigmented papillae. Dorsal side of thorax smooth or slightly wrinkled. Prosternal extension undifferentiated, or anteriorly with specific color pattern. Prosternum distinctly elevated above head medially and laterally in most species (Fig. 29A ). Shape of meso- and metathorax unmodified, transverse. Setae and cuticular spines present on lateral region of abdominal segment I (Fig. 29E ).

Spiracles. Spiracles on posterior ~ ⅓ of cephalothorax slightly elevated, with anterolateral or anterodorsal orientation.

Diagnosis of male cephalotheca.

Differing from other genera in the following characters. Diameter of genae between maxillary base and compound eye at least 2 × as large as diameter of vestigial antenna. Paired furrow of supra-antennal sensillary field indistinct or absent. Cephalotheca usually of nearly circular shape (Fig. 31A ). Antennal diameter ca. as long as width of mandible (Fig. 31E ). Mandible directed anteromedially.

Description of male cephalotheca.

Shape and coloration. In frontal view rounded, nearly circular, in lateral view pointed anteriorly. Coloration with a pattern of dark and slightly paler shades.

Cephalothecal capsule. Compound eyes with dark individual ommatidia well visible on paler ocular background. Very conspicuous clypeal lobe straight in frontal view, prominent in lateral view, bulging. Sensilla mainly concentrated on clypeal lobe. Frontal impression indistinct. Occipital bulge absent. Diameter of genae between maxillary base and compound eye large,> 2 × as large as diameter of vestigial antenna.

Supra-antennal sensillary field. Kidney-shaped and bulging, delimited medially by weakly developed frontal impression. Distinct furrows not visible.

Vestigial antenna. Of standard shape, small, sometimes with incomplete torulus, and with small plates or cavities (Fig. 31C ). Periantennal area not clearly delimited from supra-antennal sensillary field.

Labrum. Labral area distinct, with setae on dorsal field.

Mandible. Anteromedially directed. Tooth pointed, not reaching area of mandibular bulge basally. Bulge with sensilla.

Maxilla. Distinct, prominent, completely dark. Vestige of palp distinct.

Labium and hypopharynx. Labium distinct between and below maxillae, dark. Praementum and postmentum indistinctly separated by furrow. Hypopharyngeal protuberance absent.

Mouth opening. Poorly visible, partially covered by ventral labral field, arcuate.

Phylogenetic relationships.

According to Benda et al. (2019) part of a clade of a New World origin, also containing Leionotoxenos Pierce.

Diversity and distribution.

Including 16 valid species, restricted to the New World.

Hosts.

Various wasps from three families, but mostly sphecids ( Sphecidae : Sphecinae , Ammophilinae ), rarely Tachytes ( Crabronidae : Crabroninae ) and Zethus ( Vespidae : Zethinae ).

Comments.

The genus Eupathocera was described by Pierce (1908) based on his concept that a new genus of Strepsiptera should be established if it utilizes a different host genus. The description of the male was too short and superficial. It was later synonymized with Pseudoxenos ( Bohart 1937) and then with Paraxenos ( Kinzelbach 1971b). We restore Eupathocera from synonymy and classify it as a valid genus, based on the molecular phylogeny ( Benda et al. 2019, 2021) and morphological characters newly reported here. We classify the names Ophthalmochlus , Ophthalmochlus (Isodontiphila) , Homilops , and Sceliphronechthrus as synonyms of Eupathocera . Based on morphological characters, species parasitising Pachodynerus ( Vespidae ) were assigned to Eupathocera .

Figures

Figure 28. Eupathocera luctuosae (Pierce), host, female, cephalothorax, photomicrographs A Ammophila sp. stylopized by female of E. luctuosae, lateral view B detail of host abdomen with adult female inside C ventral side of cephalothorax D dorsal side of cephalothorax. Abbreviations: pp - pigmented papillae, sc - spiracular corner.

Figure 29. Eupathocera luctuosae (Pierce), female, cephalothorax, SEM micrographs A ventral side B dorsal side C left vestigial antenna, dorsal side D right vestigial antenna, dorsal side E left lateral border of abdominal segment I below spiracle, dorsal side F detail of anterior border of cephalothorax, dorsal side. Abbreviations: a - vestigial antenna, at - antennal torulus, lehc - lateral extension of head capsule, paa - periantennal area, pst - prosternum, ssf - supra-antennal sensillary field, sssf - sensillum of supra-antennal sensillary field.

Figure 30. Eupathocera luctuosae (Pierce), female, 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: fr - frontal region, ssf - supra-antennal sensillary field.

Figure 31. Eupathocera cf. inclusa (Oliveira & Kogan), male, cephalotheca, photomicrographs, SEM micrographs A frontal view B lateral view C vestigial antenna D frontal view E mouthparts. Abbreviations: a - vestigial antenna, fi - frontal impression, md - mandible, mx - vestige of maxilla.