Review of Palpostilpnus Aubert (Hymenoptera, Ichneumonidae, Phygadeuontinae), with the description of ten new species

The taxonomic limits of Palpostilpnus Aubert, 1961 are reviewed. The genus is characterized mainly by having a very elongated maxillary palp; head short and depressed, with mandible small and with distinct basal groove; ovipositor short and slender, needle-like. A total of seventeen species are recognized, of which ten are described as new: P. aki sp. nov., P. angka sp. nov., P. angkor sp. nov., P. hainanensis sp. nov., P. mangrovi sp. nov., P. pterodactylus sp. nov., P. ranui sp. nov., P. singaporensis sp. nov., P. tamasek sp. nov. and P. trifolium sp. nov. The combination Palpostilpnus rufinator (Aubert, 1961) stat. rev. is proposed. An illustrated key to the known species of the genus is provided.

All ichneumonid specimens from the Singapore Mangrove Insect Project and Nee Soon Swamp Forest Project (Kutty et al. 2018) were barcoded and pre-sorted into putative species ("MOTUs") at NUS. This was feasible due to the development of fast and cost-effective NGS barcoding (Meier et al. 2015;Wang et al. 2018). NGS barcoding either uses an antenna for direct PCR (Wong et al. 2014) or DNA is obtained using quick-extraction methods without damaging the specimens (see Wang et al. 2018). All barcoded specimens are grouped into Molecular Operational Taxonomic Units (MOTUs) before being checked for congruence with morphology ("reverse workflow for specimen processing": Wang et al. 2018). This workflow also allows for the association of immatures, males and females (Yeo et al. 2018).
In the case of the ichneumonid specimens from Singapore, the MOTUs were congruent with the species that are here described on the basis of morphological characters.
Images were acquired digitally using the following systems: a Leica MC 170HD digital camera attached to Leica S8APO microscope (SCAU); a Dun Inc. Passport II microphotography system (fitted with a Canon 65 mm 5 × MPE lens) (NUS); a Microscopic Solutions TM macropod imaging system using multiple (typically 75) focal planes, with stacks of photographs being combined using either Helicon Focus or Zerene Stacker software (using the "pmap" mode) into a single extended focus image; a Leica M205 C stereo microscope and the stacking software LAS ver. 4 at increments of 20-50 steps (HKU). All images were further processed in Adobe Photoshop ® for minor adjustments.
Standardized photographs of the mesosoma in lateral view ( Fig. 4A) for all analysed taxa were produced using either a Microptics ML-100 digital imaging system, with a Canon EOS 60D camera attached to Infinity K2 and HDF lenses and a ML-1000 stroboscopic lighting system, or an EntoVision system (GTVision, Hagerstown, Maryland), including a Leica Z16 zoom lens attached to a JVC KY-75U 3-CCD digital video camera that feeds image data to a desktop computer. The shape of the mesosoma was assessed using seven landmarks recorded with the software ImageJ (Schneider et al. 2012). These landmarks were placed on seven precise morphological features of the mesosoma to provide an objective and reproducible assessment of shape (Fig. 4B). To avoid biases derived from sexual dimorphism, each species was estimated using a female specimen. Landmark data for the species of Palpostilpnus is available in the Supplementary Material.
Landmarks were aligned and superimposed using a generalized Procrustes analysis (Dryden & Mardia 1993) in the package geomorph (Adams et al. 2014), removing information such as size and orientation to focus purely on geometric shapes. Mean shapes were then calculated for each taxon and the shape variation was explored in a principal component analysis (PCA) of the coordinates projected into the linear tangent space (Rohlf 1999) (Fig. 4B). Two principal components (PC1 and PC2) of the shape space for the mesosoma, plotted over a Procrustes-aligned tangent space. Gray dots represent the general ichneumonid morphospace as represented by 347 species from eleven subfamilies. Orange dots and polygon delimit the morphospace occupied by species of the palpator group, and blue dots and polygon represent species of the hainanensis group. Objects at each extremity of the X-axis are deformation grids representing the mean shapes at the extreme of the first principal component.

Remarks
The most readily recognizable diagnostic feature of Palpostilpnus is the very long maxillary palp, reaching the base of the hind coxa. Although very characteristic, this trait is not unique of Palpostilpnus: most of the genera placed in Townes' subtribe Chiroticina show somewhat elongated palpi. Palpostilpnus can be readily differentiated from these taxa by having the mandible small and slender, with a basal transverse groove, and a very slender, needle-like ovipositor. Since P. rufinator (Aubert, 1961) stat. rev. also shows all these character states, and bears much more morphological and biogeographical affinities with the remaining species of Palpostilpnus than with Townostilpnus chagrinator Aubert, 1961(Aubert 1961Di Giovanni & Scaramozzino 2019), we hereby transfer it back to Palpostilpnus.
The characteristic body shape is another diagnostic feature of Palpostilpnus, with the head being short and depressed, and the mesosoma stout and obliquely sloped. The PCA derived from geometric morphometric data (Fig. 4B) clearly shows that the shape of the mesosoma in species of this genus is fairly distinct from all other analyzed species. The results also support the division of the species recognized as Palpostilpnus into two reasonably clear species groups. Both show the distinctive features of the genus such as the long palp, the needle-like ovipositor and the obliquely sloped mesosoma. However, one group shows a somewhat elongated (more than 1.4 times as long as its height) and strongly slanted mesosoma (e.g., P. ranui sp. nov.), while in the other group the mesosoma is very short, stout (1.25-1.4 times as long as its height) and only slightly obliquely slanted (e.g., P. singaporensis sp. nov.). While it is unclear whether these two groups represent reciprocally monophyletic units, we suggest that they are informally designated as two species groups: (1) the palpator group for the "stout" species, including P. angkor sp. nov., P. brevis, P. maculatus, P. palpator (Aubert, 1961), P. papuator, P. rufinator stat. rev., P. singaporensis sp. nov. and P. striator; (2) the hainanensis group for the "elongated" species, including P. aki sp. nov., P. angka sp. nov., P. hainanensis sp. nov., P. mangrovi sp. nov., P. pterodactylus sp. nov., P. ranui sp. nov., P. rotundatus, P. tamasek sp. nov. and P. trifolium sp. nov.
We have also encountered specimens that show a similar habitus to the species of Palpostilpnus recognized herein, with a depressed head and a short, stout, obliquely sloped mesosoma. However, these species lack the long palpi observed in the species of this genus. Hence, we prefer to wait for a comprehensive phylogenetic assessment of the species of Palpostilpnus and similar taxa before deciding upon the placement of these species.

Biology
Unknown.

Distribution
Oriental and Australasian.

Description Female
Size. Fore wing length 3.41 mm. Body oblique elongate, 1.42 times as long as its height (Fig. 5A).
Colour. Head black. Mandible whitish yellow with teeth apically yellowish brown. Palpi white. Antenna black brown, scape yellowish brown, ventral side of petiole light brown, ventral side from eighth flagellomere to apex brown. Mesosoma yellowish brown, mesoscutum centrally and laterally black brown; apex of scutellum fuscous; mesopleuron with epicnemium black; basal half of propodeum fuscous and central area from base to apex black. Fore and middle legs brownish yellow, fore and middle trochanters whitish yellow, mid tibia and tarsus very lightly fuscous; hind coxa brownish yellow, trochanter fuscous, hind femur brownish yellow with apical 0.3 fuscous, hind tibia fuscous with basal 0.5 whitish yellow; hind tarsus fuscous with basal half of basitarsus and ventral sides of second to fifth segments brownish yellow. T1 entirely black; T2 with basal half and apical margin whitish yellow, with a transverse black band behind middle; T3-T4 black brown with basal and apical margins whitish yellow. Wings hyaline, veins and stigma fuscous. Ovipositor sheath slightly fuscous.

Remarks
This species is similar to P. rotundatus Sheng & Sun, 2013, but differs from it by the absence of the median propodeal longitudinal carina (Fig. 6C). It is also similar to P. trifolium sp. nov. and P. tamasek sp. nov., from which it differs by the entirely reddish anterior and lateral part of the mesonotum (Fig. 5E) and entirely reddish scutellum (vs black anterior and yellowish lateral part of mesonotum and black scutellum in the latter species) and by the long T1 (2.35 times as long as apically broad, vs 1.8-1.9 times as long as apically broad in P. trifolium sp. nov. and P. tamasek sp. nov.).

Etymology
The species name refers to Doi Ang Ka (Thai: ดอยอ่ างขาง), the former name of the type locality, Doi Inthanon.

Description Female
Size. Fore wing length 3.1 mm. Body oblique elongate, 1.50 times as long as its height (Fig. 7A).

Remarks
This species is similar to P. hainanensis sp. nov. and P. singaporensis sp. nov., but it differs from P. hainanensis sp. nov. by having T2 to T5 with transverse black bands (vs T2 with light brown band, T3 to T5 with a pair of brown spots laterally); hind femur with apex black (not black in P. hainanensis sp. nov.); meosoma entirely yellow (vs yellow with lower side of mesopleuron and propleuron black). It differs from P. singaporensis sp. nov. by having a shorter T1 (1.75 times as long as apically broad vs 2.0 times as long as apically broad).

Etymology
The specific name is derived from the type locality, Hainan Island.

Description Female
Size. Fore wing length 3.5 mm. Body oblique elongate, 1.60 times as long as high (Fig. 9A).
Head. Face 1.6 times as broad as high, with moderately dense setae, slightly granulose and densely punctate, sublateral portion slightly longitudinally concave, centrally weakly convex (Fig. 9B). Clypeal suture very indistinct. Clypeus slightly convex, shiny, with weak transverse striation, apically straight (not evenly convex downwards) with sharp apical margin. Mandible polished, sparsely setose, with teeth sharp, upper tooth slightly broader than lower tooth. Malar space nearly polished, equal to mandibular width. Gena glossy, polished. Vertex (Fig. 10G) smooth, posterior portion from behind ocelli to occipital carina slanted almost vertically, slightly concave. Postero-ocellar distance 3.0 times as long as ocularocellar distance (Fig. 10G). Frons with fine leathery texture, lower portion slightly concave. Antenna as long as body, with 24 flagellomeres, median portion rather thickened, first flagellomere 3.5 times as long as its apical width and 1.27 times as long as second flagellomere. Occipital carina complete, tapered upwards.
MeSoSoMa. Pronotum smooth, sparsely and shallowly punctate. Epomia indistinct. Mesoscutum ovoid, 0.8 times as long as broad, convex, with fine leathery texture and indistinct punctures (Fig. 9E). Notaulus indistinct (Fig. 9C). Scutellum evenly convex, almost smooth, with very weak and indistinct leathery texture, with shallow punctures. Postscutellum transverse, smooth. Mesopleuron polished, anterior portion with fine punctures, lower portion with punctures indistinct, pubescent with white setae; posterior portion with fine transverse wrinkles and fine indistinct punctures (Fig. 9C). Epicnemial carina very short, defined only in lower portion of mesopleuron (Fig. 9C). Sternaulus distinct, diagonally crossing mesopleuron from middle anterior part to hind lower margin of mesopleuron (Fig. 9C). Metapleuron very long and narrow, with distinct shallow punctures, distance between punctures 0.2-3.0 times diameter of punctures. Juxtacoxal carina distinct. Submetapleural carina complete. Fore wing with 1cu-a distad of M becoming Rs by 0.3 of length of 1cu-a, 3rs-m absent; distal abscissa of M spectral; length of vein Cu 1.4 times as long as 2cu-a (Fig. 10H). Hind wing with cu-a strongly inclivous and interrupted at lower 0.3. Distal abscissa of Cu spectral. Distal abscissa of M spectral. Inner profile of basal portion of fore basitarsus distinctly bent. Hind coxa with fine and uneven punctures. Hind femur stout, 3.9 times as long as its maximum width (Fig. 10D). Basal portion of hind tibia slender, gradually thick toward apex. Longer spur of hind tibia 0.6 times as long as hind basitarsus. Propodeum gradually sloping in lateral view, with sparse fine punctures (Fig. 10C). Propodeal carinae absent.
Colour. Mostly yellow. Flagellomeres starting from third, head (except basal parts of mandibles and apical margin of clypeus), lower part of pronotum and mesopleuron, area of scuto-scutellar groove, apical portion of hind tibia and apical portion of fifth tarsomere, transverse marks in hind part of T1, transverse mark of T2 and ovipositor sheath black. Scape, pedicel, base of first flagellomere, mandible except teeth, maxillary and labial palpi, all coxae and trochanters yellowish white. Pterostigma and veins yellowish brown. Wings slightly yellowish hyaline.

Remarks
This species is similar to P. singaporensis sp. nov., from which it can be distinguished by the following combination of characters: metasoma almost entirely yellow (vs with broad transverse black bands) and ovipositor 1.4 times as long as hind basitarsus (vs 0.6 times in P. singaporensis sp. nov.).

Etymology
The specific epithet refers to the habitat in which this species was collected.

Description Female
Size. Fore wing length 2.3 mm. Body oblique elongate, 1.50 times as long as high (Fig. 11A).
MeSoSoMa. Pronotum coarsely punctate dorsally, smooth and shining ventrally. Epomia indistinct. Mesoscutum ovoid, 0.87 times as long as broad, comparatively convex, with coarse dense punctures. Notaulus indistinct. Scutellum evenly convex, with coarse dense punctures. Postscutellum transverse, smooth. Mesopleuron smooth, polished, shallowly and sparsely punctate, pubescent with white setae. Epicnemial carina very short, defined only on lower portion of mesopleuron. Sternaulus indistinct. Metapleuron very long and narrow, with distinct shallow punctures, distance between punctures 0.2-3.0 times diameter of punctures. Juxtacoxal carina distinct. Submetapleural carina complete. Fore wing with 1cu-a distad of M becoming Rs by 0.6 of length of 1cu-a, 3rs-m absent, distal abscissa of M spectral; ramulus present; length of vein Cu slightly longer than 2cu-a (Fig. 12E). Hind wing with cu-a spectral. Inner profile of basal portion of fore basitarsus distinctly bent. Hind coxa with fine uneven punctures. Hind femur stout, 4 times as long as its maximum width (Fig. 12C). Basal portion of hind tibia slender, gradually thick toward apex. Longer spur of hind tibia 0.5 times as long as hind basitarsus. Propodeum steeply sloping from near anterior margin to posterior end in lateral view, sparsely and coarsely punctate (Fig. 12B). Propodeal carinae partly present, forming trapezoidal combined area superomedia and area petiolaris (Fig. 12B).
Colour. Body mostly black. Scape, pedicel, first and second flagellomeres ventrally, T1 (except postpetiole black), anterior half of T2, fore margin of T3 and dorsal part of hind femur pale yellow, and tegula and legs (except hind trochanter, ventral part of hind femur and apical part of hind tibia black) white. Wings infuscate in middle.

Male
Unknown.

Etymology
The specific name is derived from the resemblance in lateral view of T1 and its carinae to the outlines of the head of a Pterodactylus sp. (with teeth!), an extinct genus of flying reptile pterosaurs.
MeSoSoMa. Pronotum smooth on lower half, finely punctate on upper half, posterior corner weakly rugose. Epomia long and strong. Mesoscutum short, 0.85 times as long as broad, with granulose texture and large shallow punctures, punctures close and tend to be rugose. Mesoscutum weakly convex anteriorly in lateral view. Notaulus absent. Scutellum flat, shiny and sparely punctate. Mesopleuron centrally smooth and polished, dorsally with 3 irregular rows of punctures; sternaulus shallow, finely punctate. Epicnemial carina reaching to upper 0.8 of mesopleuron. Sternaulus shallow, finely punctate. Mesopleural suture distinctly foveolate. Metapleuron irregularly punctate, juxtacoxal carina weak. Submetapleural carina complete. Postpectal carina interrupted in front of hind coxa. Fore wing with 1cu-a slightly distad of M becoming Rs, 3rs-m absent, distal abscissa of M spectral; ramulus absent; length of vein Cu slightly longer than 2cu-a. Hind wing with cu-a strongly inclivous and interrupted at lower 0.25. Distal abscissa of Cu pigmented in its proximal 0.4. Distal abscissa of M spectral. Inner profile of basal portion of fore basitarsus distinctly bent. Hind femur 2.4 times as long as its maximum width; hind tibia with longer spur 0.6 times as long as hind tibia. Propodeum gradually sloping in lateral view, sparsely punctate, smooth posterocentrally, shiny. Median longitudinal carina complete, third lateral area complete, pleural carina absent (Fig. 14B).
Colour. Head black. Antenna with scape whitish, pedicel and first to seventh flagellomeres yellowish brown, with eighth to apical flagellomere dorsally black brown and ventrally yellowish brown. Mandible whitish, with apical tooth black. Palpi whitish yellow. Mesosoma yellowish brown, apex of scutellum and metanotum black. Legs light brown, fore coxa and trochanter yellowish white, hind tibia with base and apex fuscous, hind tarsus whitish yellow. T1 brown with proximal base black; T2-T6 yellowish brown, centrally with a transverse black band. Ovipositor sheath light brown with apical tip fuscous. Wings hyaline, veins and stigma fuscous.

Remarks
This species is similar to P. rotundatus Sheng & Sun, 2013, but can be distinguished from the latter by the following combination of characters: occipital carina broadly absent dorsally; T1 short and stout (1.5 times as long as apically broad vs 1.8 times as long as apically broad in P. rotundatus). This species can easily be separated from other congeneric species by is occipital carina being dorsally broadly absent.  16A). T1 2.2 times as long as apically broad (Fig. 15D). Wings hyaline (Fig. 16D).

Etymology
The specific name is derived from the type locality, Ranu River, on the island of Sulawesi, Indonesia.

Description Female
Size. Fore wing length 3.2 mm. Body obliquely elongate, 1.80 times as long as high (Fig. 15A).
Head. Face 1.6 times as broad as high, centrally with faint convexity, with fine granulose texture and dense punctures, distance between punctures 0.2-0.3 times diameter of punctures. Clypeal suture weak but distinct. Clypeus distinctly convex, shiny, with distinct transverse striation, apical margin sharp, slightly convex. Basal portion of mandible smooth; teeth sharp, dorsal tooth pointed, slightly longer than ventral tooth. Malar space smoother than face, slightly striate, 1.1 times as long as basal width of mandible. Gena glossy, sparsely punctate, near dorsal corner of eye with slight swelling, but not forming distinct carina. Vertex (Fig. 16B) punctate, posterior portion from behind ocelli to occipital carina steeply slanted. Postero-ocellar distance 2.8 times ocular-ocellar distance. Frons densely punctate, lower portion slightly concave. Antenna as long as body, with 25 flagellomeres, median portion moderately thickened. Occipital carina complete, tapered upwards.
MeSoSoMa. Pronotum ventrally smooth, dorsally distinctly punctate. Epomia distinct along posterior margin of collar, indistinct from other striations when diverging from pronotal collar. Mesoscutum (Fig. 15E) ovoid, 0.95 times as long as broad, comparatively convex, with fine leathery texture and dense punctures. Notaulus indistinct. Scutellum evenly convex, with shallow punctures. Postscutellum with few lateral punctures. Mesopleuron (Fig. 15C) centrally mostly smooth and shiny, externally to this central area distinctly punctate. Epicnemial carina vestigial, only distinguishable on part of mesosternum. Sternaulus distinct, diagonally crossing mesopleuron from middle anterior part to hind lower margin of mesopleuron. Metapleuron very long and narrow, with distinct shallow punctures, distance between punctures 0.2-0.3 times diameter of punctures. Juxtacoxal carina vestigial. Submetapleural carina complete. Fore wing with 1cu-a distinctly distad of M becoming Rs, 3rs-m absent, distal abscissa of M spectral; ramulus absent; length of vein Cu distinctly longer than 2cu-a. Hind wing with cu-a strongly inclivous and interrupted at lower 0.2. Distal abscissa of Cu spectral. Distal abscissa of M spectral. Inner profile of basal portion of fore basitarsus distinctly bent. Hind coxa finely punctured on anterior face, posteriorly smooth. Propodeum (Fig. 16A) with shallow, moderately dense punctures, moderately sloping from near anterior margin to posterior end; propodeal carinae absent except for vestiges of median longitudinal carina; spiracle small, circular. MetaSoMa. T1 2.4 times as long as apically broad (Fig. 15D); petiole dorsally flat, with large shallow punctures, laterally finely punctate; petiole smooth and flat; postpetiole narrow; dorsolateral carina distinct until spiracle but apically weak; ventrolateral carina complete; spiracle small, round, not prominent. T2-T5 punctate-areolate; T2 broad posteriorly, 0.80 times as long as apically broad. T3 0.70 times as long as apically broad, parallel-sided. Ovipositor 0.23 times as long as hind tibia.
Colour. Mostly yellowish and black. Head black; basal 0.8 of mandible, scape and pedicel pale yellow; mandible apex and basal flagellomere ferruginous, flagellum gradually changing to dark brown by fourth flagellomere. Mesosoma mostly pale yellow; median portion of pronotum, posterior 0.6 of mesoscutum, axillary trough, apex of scutellum, postscutellum, mesopleuron except for anterodorsal spot, mesosternum and longitudinal dash on propodeum black. Fore and mid legs pale yellow, gradually darker towards apex. Hind coxa pale yellow; trochanter and femur ferruginous; hind tibia basally pale yellow, gradually changing to ferruginous towards apex; hind tarsus pale yellow. Wings hyaline. Pterostigma and veins yellowish brown. Metasoma mostly pale yellow or light ferruginous; postpetiole of T1 with dark ferruginous and black areas; T2-T5 with distinct sub-apical transverse stripes, black on T2 and gradually lighter until ferruginous on T5. Ovipositor sheath basally pale yellow, apically brown.

Male
Forewing 3.3 mm long. Antenna with 23 flagellomeres. Otherwise very similar to female except for slightly more slender body and secondary sexual dimorphism.

Remarks
This species is most similar to P. hainanensis sp. nov., particularly because of the obliquely elongated body and colour pattern. Palpostilpnus ranui sp. nov. can be differentiated from the latter by several relatively small differences, including more extensive black marks on the mesoscutum, mesopleuron and metasoma (Fig. 15A, C, E); tibia not apically black (vs apical 0.25 black in P. hainanensis sp. nov.); propodeum with traces of the median dorsal carina (vs entirely absent); extensive areas on anterior and posterior margins of mesopleuron densely punctate (vs mesopleuron almost entirely smooth); and epicnemial carina absent from mesopleuron (vs present on lower portion of mesopleuron).

Description
Colour. Head black. Labrum, mandible (except for black apical tooth) and palpi pale yellow. Antenna with scape and pedicle pale yellow, flagellum basally and ventrally reddish brown, dorsally from middle length to apex fuscous. Mesosoma reddish brown. Propleuron laterally fuscous; anterior margin of pronotum, anterior upper corner of mesopleuron, and anterior margin of mesoscutum and scutellum (except for black apex) yellowish brown; mesoscutum with black marks on posterior half of median lobe and lateral lobe. Metanotum, epicnemium and anterior margin of submetapleural ridge black. Propodeum basally centrally with a black mark. T1 black, T2-T6 fuscous, basally and laterally yellowish brown, and apical margins yellow. Legs yellowish brown to reddish brown, hind tibia with base and apex fuscous, hind fifth tarsomere darkened.

Remarks
This species is similar to P. angkor sp. nov. but differs from the latter by having the mesoscutum densely reticulate-punctate (vs with large shallow punctures in P. angkor sp. nov.) and the posteroocellar distance 1.25 times the ocular-ocellar distance (vs 3.4 times in P. angkor sp. nov.).

Etymology
The specific name is derived from the type locality, Tamasek, an early recorded name of a settlement on the site of modern Singapore.

Description Female
Size. Fore wing length 3mm. Body oblique elongate, 1.72 times as long as high (Fig. 17A).
Head. Face 1.6 times as broad as high, centrally slightly convex, with coarse dense punctures, distance between punctures about 0.3 times diameter of punctures (Fig. 17B). Clypeal suture very weak. Clypeus slightly convex, shiny, distinctly striated, apically straight (not evenly convex downwards) with sharp apical margin. Basal portion of mandible smooth; teeth sharp, upper teeth slightly broader than lower. Malar space smooth, 0.3 times as long as basal width of mandible. Gena glossy, smooth and shiny, forming weak swelling but no carina in dorsal part between vertex and eye margin. Vertex strongly punctate, posterior portion from behind ocelli to occipital carina slanted almost vertically, slightly concave. Postero-ocellar distance 2.40 times distance between lateral ocellus and eye margin. Frons densely punctate, lower portion slightly concave. Antenna as long as body, with 25 flagellomeres, median portion very thickened. Occipital carina complete, tapered upwards.
Colour. Body mostly ferruginous (but variable, see below). Flagellomeres starting from 2 dorsally, head (excluding basal parts of mandibles), pronotum, mesoscutum (except yellow anterior lateral edges), central part of scutellum, anterior part of mesopleuron, apical part of hind tibia, hind part of T1 and Male (Fig. 19) Mostly as in the female but T1 shorter, 1.7 times as long as apically broad, antennal flagellomeres paler ventrally, and most of mesopleuron, most of metasoma and basal part of propodeum dorsally black.

Remarks
This species is similar to P. trifolium sp. nov., but can be distinguished from the latter by having a distinctly more elongated body (1.72 times as long as high, vs 1.48 times as long as high in P. trifolium sp. nov.) and the following combination of characters: gena forming a blunt swelling in its upper part at vertex and eye margin; mesoscutum anteriorly protruding above pronotum; scutellum yellow laterally; vein 2-Cu slightly shorter than 2cu-a; ovipositor longer, 3.5 times as long as hind basitarsus (Fig. 18C).

Etymology
The specific name is derived from the generic Latin name of clover, Trifolium L., in reference to the trilobed colour pattern on the scutum of this species.

Description Female
Size. Fore wing length 4.2 mm. Body oblique elongate, 1.48 times as long as high (Fig. 20A).
MeSoSoMa. Pronotum smooth, sparsely and shallowly punctate. Epomia distinct. Mesoscutum ovoid, 0.97 times as long as broad, convex, with granulated texture and distinct punctures (Fig. 20E). Notaulus indistinct (Fig. 20E). Scutellum evenly convex, almost smooth, with distinct sparse punctures. Postscutellum transverse, smooth. Mesopleuron (Fig. 20C) smooth, shiny, anterior portion with shallow punctures; lower portion with punctures indistinct; posterior portion smooth. Epicnemial carina short, defined only in ventral portion of mesopleuron. Sternaulus indistinct, defined in middle anterior part of mesopleuron. Metapleuron very long and narrow, with distinct shallow punctures, distance between punctures 0.75-1.2 times diameter of punctures. Juxtacoxal carina absent. Submetapleural carina complete. Fore wing with 1cu-a distinctly distad of M becoming Rs, 3rs-m absent, distal abscissa of M spectral; ramulus absent; length of vein Cu slightly longer than 2cu-a (Fig. 21H). Hind wing with cu-a strongly inclivous and interrupted at lower 0.16. Distal abscissa of Cu spectral. Distal abscissa of M spectral. Inner profile of basal portion of fore basitarsus distinctly bent. Hind coxa with fine and indistinct punctures. Basal portion of hind tibia slender, gradually thick toward apex. Propodeum gradually sloping in lateral view, with sparse fine punctures. Propodeal carinae absent except apical part of medial longitudinal carina and lateral part of posterior transverse carina closing area postero-externa (Fig. 21C).

Remarks
This species is similar to P. tamasek sp. nov., but can be distinguished from the latter by the following combination of characters: body short (Fig. 20A); mesoscutum not protruding above pronotum; scutellum entirely black; lengths of veins 2-Cu and 2cu-a equal; ovipositor short, 0.9 times as long as hind basitarsus (Fig. 21E ).

Etymology
The specific name is derived from the type locality, Angkor Wat.

Description
Female Size. Fore wing length 3.3 mm. Body short and stout, 1.50 times as long as high.

Male
Unknown.

Variation
Fore wing 3.1-3.5 mm long. Antenna with 23-25 flagellomeres. Dorsoposterior corner of pronotum sometimes with small yellowish mark; anterior pale yellow arc on mesoscutum sometimes medially interrupted; pale yellow mark on mesopleuron sometimes restricted to subalar ridge; punctures on mesopleuron restricted to its margin to variously invading the central, otherwise smooth, area; black areas in propodeum covering 0.2-0.9 of its area; black marks on hind coxa and trochanter sometimes reduced; black stripe on T2 sometimes incomplete; marks on T3 and T4 variable in size, sometimes distinct as clear circular spots, sometimes almost indistinct.

Remarks
Very similar to P. maculatus Sheng & Sun, 2013, from which it can be differentiated mainly by the following characters: mesoscutum longer (as long as broad) and distinctly convex, anterior margin projecting over pronotum (vs 0.75 times as long as broad in P. maculatus, and flat, not projecting over pronotum); T1-T5 all with distinct black stripes (vs distinct stripes only at T1 and T2, while T3 and T4 with small sublateral marks); antenna shorter and stouter; postero-ocellar distance distinctly much longer (3.4 times vs 2.3 times ocular-ocellar distance).

Diagnosis
Clypeal suture very weak and indistinct. Postero-ocellar distance equal to distance between lateral ocellus and eye margin. Notaulus distinct. Hind wing with cu-a interrupted at lower 0.2. Lateral carinae of area basalis combined into one carina. Ovipositor very short, 0.4 times as long as length of hind basitarsus. T2 and T3 yellowish brown to reddish brown. Wings hyaline. Antennal flagellum with middle flagellomeres coloured white dorsally.

Remarks
This species is similar to P. palpator (Aubert, 1961), but differs from it by the following combination of characters: notaulus distinct, T2-T4 reddish (black in P. palpator), middle antennal flagellomeres coloured white, frons with fine leathery texture and unevenly punctate, ovipositor 0.4 times as long as length of hind basitarsus (2.1 times in P. palpator), fore and mid coxae white, and hind tibia dark brown.

Redescription Female
Size. Fore wing length 3.3 mm. Body short and stout, 1.45 times as long as high.
Head. Face 1.8 times as broad as high, centrally slightly convex, coriaceous-punctate (punctures best observed in oblique view). Clypeal suture absent. Clypeus slightly convex, shiny, distinctly striated, with sharp, slightly convex apical margin. Basal portion of mandible smooth; dorsal tooth lanceolate, broader than ventral tooth. Malar space coriarious, 1.4 times as long as basal width of mandible. Gena glossy, mostly smooth with sparse shallow punctures, dorsally forming two weak carinae, posterior to dorsal corner of eye and lateral ocellus. Vertex sparsely punctate, posterior portion from behind ocelli to occipital carina slanted almost vertically, slightly concave. Postero-ocellar distance 2.3 times ocularocellar distance. Frons coriaceous-punctate, lower portion not distinctly concave. Antenna slightly shorter than body, with 27 flagellomeres, first flagellomere 1.1 times as long as second flagellomere, median portion of antenna moderately thickened. Occipital carina complete.
MeSoSoMa. Pronotum punctate-areolate. Epomia distinct. Mesoscutum short, 0.75 times as long as broad, almost flat, with granulated texture and large, shallow punctures. Notaulus indistinct. Scutellum flat, elongate, with fine sparse punctures. Postscutellum smooth. Mesopleuron centrally smooth, shiny, distinctly punctate on speculum, ventrad of sternaulus and anteriorly to epicnemial carina. Epicnemial carina reaching dorsal 0.8 of mesopleuron. Sternaulus distinct on anterior 0.6 of mesopleuron. Metapleuron long and narrow, shallowly punctate-areolate. Juxtacoxal carina short but distinct. Submetapleural carina complete. Fore wing with 1cu-a distinctly distad of M becoming Rs, 3rs-m absent, distal abscissa of M spectral; ramulus present; vein Cu slightly longer than 2cu-a. Hind wing with cu-a strongly inclivous and interrupted at lower 0.3. Distal abscissa of Cu spectral. Distal abscissa of M spectral. Inner profile of basal portion of fore basitarsus distinctly bent. Hind coxa anteriorly shallowly punctate, posteriorly smooth. Propodeum mostly covered by dense shallow punctures, posterocentrally smoother, steeply sloping from near anterior margin to posterior end; propodeal carina absent, lateral longitudinal and posterior transverse carinae only represented by vestigial traces on posterior end of propodeum.
Colour. Mostly yellowish and black. Head black; basal 0.8 of mandible, scape and ventral face of pedicel pale yellow; mandible apex, dorsal face of pedicel and basal flagellomeres ferruginous, flagellum gradually changing to dark brown by fifth flagellomere. Mesosoma mostly pale yellow; pronotum except collar, propleuron, small spot on anterior margin of mesoscutum, posterior 0.7 of mesoscutum, axillary trough, most of mesopleuron, mesosternum and sublateral spots on propodeum black. Fore and mid legs gradually darker towards apex. Hind coxa with small black marks on mesal face; hind trochanter and femur ferruginous, trochanter with lateral black spots; hind tibia basally pale yellow, gradually changing to ferruginous and black towards apex; hind tarsus pale yellow except for black T5. Wings hyaline. Pterostigma and veins yellowish brown. Metasoma mostly pale yellow or light ferruginous; T1 dorsally with transverse black stripe opposite spiracle, area immediately adjacent to stripe ferruginous; T2 with distinct sub-apical transverse black stripe; T3 and T4 with small (almost indistinct on T4) sublateral black marks. Ovipositor sheath basally pale yellow, apically brown.

Male
Unknown.

Variation
Fore wing 3.0-3.5 mm long. Antenna with 26-27 flagellomeres. Mesopleuron sometimes with yellow spot on posteroventral corner. Black areas in propodeum covering 0.05-0.5 of its area (specimens from Brunei with less extensive black marks). Black stripe on T2 sometimes incomplete; marks on T3 and T4 variable in size, sometimes distinct as clear circular spots, sometimes almost indistinct.

Remarks
This species is similar to P. angkor sp. nov., from which it can be differentiated mainly by the following characters: mesoscutum very short, 0.75 times as long as broad, and flat, not projecting over pronotum (vs as long as broad and distinctly convex, anterior margin projecting over pronotum in P. angkor sp. nov.); black stripes on metasoma restricted to T1 and T2, with small sublateral marks on T3 and T4 (vs distinct stripes only on T1-T5); antenna longer and more slender; postero-ocellar distance distinctly much shorter (2.3 times vs 3.4 times ocular-ocellar distance); and T1 more distinctly widened apically (apical width 3.2 times vs 2.5 times as wide as basal width).

Redescription
Female (holotype) Size. Fore wing length 4.1 mm. Body short and stout, 1.35 times as long as high (Fig. 23). Head. Face 1.61 times as broad as high, centrally slightly convex, finely granulose (Fig. 23D). Clypeal suture indistinct. Clypeus slightly convex, shiny, sparsely punctate, apical margin moderately thick and truncate. Basal portion of mandible with weak and fine punctures; upper and lower margins almost parallel; teeth sharp, upper tooth approximately as long as lower tooth. Malar space with fine leathery granulose texture. Malar sulcus indistinct. Malar space approximately 0.67 times as long as basal width of mandible. Gena glossy, smooth and shiny, with no distinct carina dorsally between vertex and eye. Vertex (Fig. 23E) smooth, polished; posterior portion from behind ocelli to occipital carina slanted almost vertically, slightly concave. Postero-ocellar distance 2.45 times ocular-ocellar distance. Frons smooth and polished, lower portion slightly concave. Antenna slightly shorter than body, with 21 flagellomeres, median portion moderately thickened.
MetaSoMa (Fig. 23F). T1 approximately 2.5 times as long as apically broad; portion just before posterior apex bulging and distinctly broader than posterior margin; petiole flat, laterally smooth, dorsally with fine longitudinal striae extending into postpetiole; median dorsal carina absent; dorsolateral and ventrolateral carinae weak to almost indistinct, fading towards posterior apex; spiracle small, round, not prominent. T2 and T3 covered with fine, but distinct longitudinal striae. T2 long and widened posteriorly, approximately 1.4 times as long as apically broad. T3 approximately 1.0 times as long as apically broad, parallel-sided. Ovipositor 2.1 times as long as hind basitarsus (Fig. 23B).

Male
Unknown.

Remarks
Palpostilpnus palpator is similar to P. brevis Sheng & Broad, 2011, but can be distinguished from the latter by the following combination of characters: notaulus indistinct, antenna and metasoma black, frons smooth, ovipositor 2.1 times as long as hind basitarsus (vs 0.4 times in P. brevis).

Description
Female (holotype) Size. Fore wing length 3.8 mm. Body short and stout, 1.40 times as long as high (Fig. 24).
MeSoSoMa. Pronotum rugulose. Epomia indistinct. Mesoscutum wide and short, convex, mostly coriarious, with short transverse striae over notaulus. Notaulus distinct, reaching past half length of mesoscutum. Scutellum convex, with strong, regularly spaced longitudinal striae. Postscutellum transverse, smooth. Mesopleuron irregularly rugose, with sparse, small, smooth areas, sparsely pilose. Epicnemial carina short, extending through ventral 0.5 of mesopleuron (Fig. 24D). Sternaulus distinct, extending over entire mesopleuron. Juxtacoxal carina distinct. Submetapleural carina complete. Fore wing with 1cu-a distinctly distad of M becoming Rs, 3rs-m absent, distal abscissa of M spectral; ramulus absent; length of vein Cu slightly longer than 2cu-a. Hind wing with cu-a strongly inclivous and interrupted at lower 0.3. Distal abscissa of Cu spectral. Distal abscissa of M spectral. Inner profile of fore basitarsus with basal half distinctly bent. Hind coxa punctate along lateral longitudinal portion, elsewhere smooth. Hind femur stout, length 3.9 times its maximum width, with distinct ridge-like swelling on basal 0.3 of posterior face. Basal portion of hind tibia slender, gradually thick toward apex. Longer spur of hind tibia 0.35 times as long as length of hind basitarsus. Propodeum steeply sloping in lateral view, centrally smooth, anterior and lateral portions rugulose. Posterior transverse and median longitudinal carinae well developed, complete. MetaSoMa (Fig. 26A). T1 approximately 2.5 times as long as apically broad; portion just before posterior apex bulging and distinctly broader than posterior margin; petiole flat, laterally smooth, dorsally with fine longitudinal striae extending into postpetiole; median dorsal carina absent; dorsolateral and ventrolateral carinae anteriorly distinct, fading towards posterior apex; spiracle small, round, not prominent. T2-T3 covered with fine, but distinct longitudinal striae. T2 long and widened posteriorly, approximately 1.4 times as long as apically broad. T3 approximately 1.0 times as long as apically broad, parallel-sided. Ovipositor 2.1 times as long as hind basitarsus.

Remarks
This species is similar to P. striator Aubert, 1961, from which it can be distinguished by the following combination of characters: frons, mesonotum and mesosternum finely punctate, entirely dull, ovipositor 2.1 times as long as length of hind basitarsus (vs 1.5 times in P. striator).

Description
Female (holotype) Size. Fore wing length 4.0 mm. Body short and stout, 1.35 times as long as high (Fig. 25).

Remarks
This species is similar to P. striator (Aubert, 1961), from which it can be distinguished by the following combination of characters: mandibles sub-basally swollen, with a basal, transverse groove; propodeum sloping gradually; mesosoma mostly reddish (Fig. 25A); fore wing with one infuscate transverse band; antenna, scape and trochanters without white colouration.

Etymology
The specific name is derived from the name of the type locality, Singapore.

Description
Female (holotype) Size. Fore wing length 3.3 mm. Body short and stout, 1.28 times as long as high (Fig. 26A).
Colour. Body mostly yellow. Antenna dorsally, head, posterior stripe on T1-T4 and apical part of hind tibia black. Apex of mandible reddish. Antenna ventrally brownish. Scape ventrally, palpi, fore and middle trochanters, fore femur, apical part of metasoma and hind tarsus pale yellow.

Male
Unknown.

Variation
Fore wing 3.3-3.5 mm long. Antenna with 26-27 flagellomeres. Specimen from Brunei with black transverse stripe on apex of mesoscutum; black spots on hind tibia smaller; metasoma without distinct black stripes, but slightly darkened on posterior portion; ovipositor 0.4 times as long as hind basitarsus.

Remarks
This species is similar to P. hainanensis sp. nov., but it can be distinguished from the latter by having a distinctly stouter body (1.28 times vs 1.60 times as long as high in P. hainanensis sp. nov.) and the following combination of characters: T1 2.0 times as long as apically broad (1.8 times in P. hainanensis sp. nov.), ovipositor 0.3 times as long as hind basitarsus (1.3 times in P. hainanensis sp. nov.), mesopleuron entirely yellow and hind margin of T1-T4 black or at least distinctly darkened. (Aubert, 1961) Fig. 28 Townostilpnus (Palpostilpnus) striator Aubert, 1961: 59.

Diagnosis
Body short and stout. Mesopleuron striated. Propodeal carinae partly present. Ovipositor 1.5 times as long as hind basitarsus. Body mostly black, with middle flagellomeres dorsally, palpi, trochanters, basal part of hind tibia and T6 white. Wings infuscate by two bends.

Description
Female (holotype) Size. Fore wing length 4.0 mm. Body short and stout, 1.25 times as long as high (Fig. 28A).
Head. Face 1.45 times as broad as high, centrally slightly convex, finely granulose (Fig. 28D). Clypeal suture indistinct. Clypeus slightly convex, matte, transversely striate, apically evenly convex downwards, with sharp apical margin. Mandible basally smooth; teeth sharp, dorsal tooth broad and decurved, much longer than ventral one. Malar space granulated, 0.6 times as long as basal mandible width. Gena glossy, smooth and shiny, with no distinct carina dorsally between vertex and eye. Vertex smooth to coriarious; posterior portion from behind ocelli to occipital carina slanted almost vertically, slightly concave. (Aubert, 1961), holotype, ♀ (USUC). A-B. Lateral habitus. C. Mesopleuron. D. Head, anterior view. members of the predator fly family Hybotidae hunt Ichneumonidae (personal report). Some hybotids are known for the resemblance of their wing colouration with that of some parasitoids, e.g., Holceupelmus Cameron, 1905 egg parasitoids, which could be a mimetic association (Smith 1969). The same infuscate colour pattern occurs on the wings of several species of Palpostilpnus (P. mangrovi sp. nov., P. rufinator, P. striator, P. papuator).

Fig. 28. Palpostilpnus striator
The habitats of those species for which it is known are woodlands (Table 1), either evergreen broadleaved (Figs 2A-B, 3) or deciduous mixed forest at mountainous sites, or dipterocarp, swamp or intertidal mangrove forests in the lowlands. The exception is Pak Sha O in Hong Kong, which is a lowland site; however, it is surrounded by mature secondary evergreen forest. These habitats invariably represent fragile ecosystems, which are increasingly under the threat of destruction, either indirectly (global warming, and other environmental impacts) or directly (habitat destruction). In the face of rapid habitat loss in Southeast Asia in general, coupled with the fact that most species collected are singletons, implying a certain level of rarity, we hope that this work will encourage more research and hopefully, down the line the formulation of conservation strategies. Indeed, while the sampling methodology did not yield significant biological facts, the simple Malaise trap nevertheless provided for metrics that doubled the known number of representatives of the genus, also increasing our knowledge of distribution and species groups.
Palpostilpnus has an Oriental and Australasian distribution, with most of the species known from Southeast Asia. All the species with known habitats are associated with woodland areas (Table 1,  . We must point out that many of the species are represented by singletons, and in the face of rapid habitat destruction in Southeast Asia we see value in describing and documenting 10 species new to science. Our work can hopefully stimulate extra attention to this problem and encourage further studies of the global fauna of Palpostilpnus. We expect that additional new species of this taxon will be discovered in the future.