Revision of the endemic Afrotropical genus Tetractenion (Hymenoptera, Ichneumonidae) with an identification key to genera of Banchinae for the region

Abstract The Afrotropical banchine fauna comprises 12 genera: Apophua Morley, Atropha Kriechbaumer, Cryptopimpla Taschenberg, Exetastes Gravenhorst, Glyptopimpla Morley, Himertosoma Schmiedeknecht, Lissonota Gravenhorst, Sjostedtiella Szépligeti, Spilopimpla Cameron, Syzeuctus Förster, Tetractenion Seyrig, and Tossinola Viktorov. A well-illustrated revised key to the genera using high definition images is provided, and the endemic Afrotropical genus Tetractenion is revised, previously represented by two described species. Four new species are described: T.ibayaensissp. nov., T.pascalisp. nov., T.pseudoluteasp. nov., and T.roseisp. nov. The first species-level identification key is provided for this rare genus. Based on morphological attributes the hypothesis is presented that the species in this genus are probably nocturnal. All images and online interactive Lucid keys are available at: www.waspweb.org and the associated underlying data is made available as Suppl. materials 1, 2 LIF3 files to this paper for inter-exchange with other key production software.


Introduction
Banchinae is a cosmopolitan group of moderately small to large-sized parasitoid wasps (Gauld et al. 2002). The group is usually well represented in all faunas and amongst the most commonly collected of all ichneumonids (Gauld et al. 2002;Broad et al. 2011). There are roughly 1800 described species and 66 genera of Banchinae currently recognized (Khalaim and Ruíz-Cancino 2012;Maeto 2012, 2014;Broad 2014;Choi et al. 2015;Reynolds Berry and van Noort 2016;Herrera-Florez 2017;Vas 2017;Watanabe 2017Watanabe , 2018Watanabe , 2020Kasparyan and Kulitzky 2018;Li et al. 2018;Sheng et al. 2018;Watanabe and Sheng 2018;Kang et al. 2019Kang et al. , 2020Yu et al. 2020). With the banchine fauna poorly known for many areas of the world, and a number of undescribed genera and species from tropical regions preserved in museum collections, the number of species is certainly far greater (Broad et al. 2011).
Most Banchinae can be readily diagnosed by the following characters: 1) a submetapleural carina anteriorly generally expanded into a lobe; 2) an arched posterior transverse carina of the propodeum; and 3) a dorsal apical notch on the ovipositor (Wahl and Sharkey 1993;Broad et al. 2011). "However, some or all of these characters do not apply to aberrant genera and species" (Broad et al. 2011) and therefore these morphological characters cannot be classified as synapomorphies for the Banchinae. An additional two apomorphies were later proposed (Gauld and Wahl 2000;Broad et al. 2011): firstly, the subapical flagellomeres of female antennae possess elongate placoid sensilla only on the dorsal surface, with smaller, rounded sensilla on the ventral surface; and secondly, the posterior corner of the pronotum is rounded, slightly twisted and flattened. While within the Ophioniformes group (Ophioninae, Ctenopelmatinae, Banchinae, Mesochorinae, Nesomesochorinae, Metopiinae, Campopleginae, Tatogastrinae, Cremastinae, Tersilochinae, Anomaloninae, Neorhacodinae, Oxytorinae, Stilbopinae, Sisyrostolinae, and Lycorinae; Gauld 1985;Wahl 1991Wahl , 1993Quicke et al. 2009) these two characters are phylogenetically informative, it has been established that they are not synapomorphic for the subfamily Banchinae (Broad et al. 2011).
Morphologically, Banchinae can be subdivided into three tribes namely Banchini, Glyptini, and Atrophini (Townes and Townes 1973;Yu et al. 2020). In addition to having very short ovipositors, Banchini differs from the other tribes by having eight or more sensilla on the larval prelabium (Quicke 2015). Atrophini possess a reduced hypostoma (Quicke 2015) and Glyptini share similar modifications on the metasoma with Lycorina and some Pimplinae taxa, in that taxa within Glyptini typically possess triangular areas on tergites II-IV, delimited by paired, lateromedian grooves , though the precise pattern of grooves differs in the former taxa. Given that Pimplinae and Lycorininae are distantly related subfamilies to Banchinae , the similarity of these structures is likely to be the result of analogous character states that appear similar as a result of convergence.
Within the Afrotropical region, the subfamily comprises 12 genera and 187 described species: Apophua Morley, Atropha Kriechbaumer, Cryptopimpla Taschenberg, Exetastes Gravenhorst, Glyptopimpla Morley, Himertosoma Schmiedeknecht, Lissonota Gravenhorst, Sjostedtiella Szépligeti, Syzeuctus Förster, Spilopimpla Cameron, Tetractenion Seyrig, and Tossinola Viktorov. A dichotomous identification key to banchine genera within the Afrotropical region was last produced by Townes and Townes (1973), providing the most comprehensive taxonomic treatment to date. Nevertheless, the generic key is outdated and not supported with applicable illustrations of character states. Subsequent to this treatment, the genus Glyptopimpla was removed from synonymy with Teleutaea Förster and re-instated as a valid genus and as a senior synonym of Zygoglypta Momoi and Orientoglypta Kuslitzky (Gupta 2002).
Tetractenion, placed in the tribe Banchini, is a very rare genus restricted to the Afrotropical region (Townes 1969;Yu et al. 2020). Until now, Tetractenion included only two species, T. luteum Seyrig, recorded from continental central Africa (Democratic Republic of Congo and Kenya) and T. acaule Seyrig, recorded from Madagascar (Seyrig 1932(Seyrig , 1935. The purpose of this paper is to revise the genus Tetractenion, and to provide well-illustrated updated keys to the genera of Banchinae in the Afrotropical region, and to the species of Tetractenion. Online Lucid keys are available on www. waspweb.org and the associated underlying data is made available as Suppl. materials 1, 2: LIF3 files to this paper for inter-exchange with other key production software.

Photographs
Specimens were either pinned or point mounted on black, acid-free cards for examination (using a Leica M205C stereomicroscope with LED light source), photography, and long-term preservation. Images were taken using the Leica LAS 4.4 system which comprised a Leica Z16 microscope with a Leica DFC450 Camera with a 0.63× video objective attached. The imaging process, using an automated Z-stepper, was managed using the Leica Application Suite V 4.4 software installed on a desktop computer. Diffused lighting was achieved using a Leica Dome. Images of the types held in Musée Royal de l'Afrique Centrale, Tervuren (RMCA) were kindly made available by Stéphane Hanot and Arnaud Henrard and those in the Muséum national d'Historie naturelle, Paris (MNHN) were kindly made available by Agnièle Touret-Alby. All images presented in this paper are available at www.waspweb.org (van Noort 2020).
The first three measurements (absolute measures) were measured on all specimens in the type series, with measurements from the primary type reported separately in brackets if necessary.

Identification keys
Identification keys were produced in two formats to facilitate accessibility by a range of end-users and to meet the requirements of publishing both static and dynamic interactive keys under an open access model Sharkey et al. 2009): 1. Traditional dichotomous keys these are published below and also made available as interactive keys supported by links to species pages on www.waspweb.org; 2. Online interactive Lucid matrix keys were produced, hosted on www.waspweb.org, and made available as Suppl. materials 1, 2: LIF3 files to this paper for import to, and interexchange with other key production software. The LIF3 file is an XML-based file that stores all the Lucid4 key data, allowing exchange of the key with other key developers Sharkey et al. 2009). In contrast to dichotomous keys where a choice needs to be made at each key couplet to continue, Lucid matrix keys use a different approach where relevant states from multiple character features can be selected independently until identification is achieved (www.lucidcentral.org). All keys were produced using high quality annotated images, highlighting diagnostic characters that are integrated into the key above each couplet. This is a user-friendly output making the keys readily accessible to a wide range of users with diverse expertise. This key format circumvents the requirement of familiarity with morphological terminology associated with the particular group, because the characters are visually illustrated making the keys usable by the lay person (van Noort et al. 2015).

Results
Key to Banchinae genera of the Afrotropical region -Tergites II-IV without a median pair of oblique grooves (a); Cu1 often longer than cu-a, but may be shorter (b -Hind wing with Cu1 shorter than cu-a such that Cu2 arises above the middle of these combined veins (nervellus of Townes) (a); fore wing with 3rs-m always present, areolet rhomboidal (a); mesopleuron usually higher than wide (b) .. Occipital carina joining hypostomal carina above base of mandible (A); ovipositor sheath short to long, 0.14-1.8× as long as hind tibia (B); mandibular teeth usually subequal in length (C); apical clypeal margin normal (C) ....... Exetastes -Occipital carina joining hypostomal carina at base of mandible (a); ovipositor sheath always short, 0.1-0.2× as long as hind tibia (b); lower tooth of mandible always longer than upper tooth (c); clypeus apically invaginated (c) ..Tetractenion Details of morphological characters that were used to update the key to Afrotropical banchine genera 1. Occipital carina with strong curve prior to meeting hypostomal carina: this character (couplet 1A), although noted in the global generic key by Townes (1969), was not included in the previously published generic key to Afrotropical Banchinae (Townes and Townes 1973). This is a strong and reliable character distinguishing Apophua from the remaining Glyptini genera, Sjostedtiella and Glyptopimpla.
2. Shape of the areolet when closed: the shape of the areolet has been found to be a useful character to separate the tribes/genera. When distinguishing the tribes Atrophini and Banchini, the areolet in Exetastes and Tetractenion is always large and rhomboidal with a very short stalk, whereas in those Atrophini that possess an areolet it is always small, but variably shaped (couplet 4A, a). An anteriorly truncate areolet (couplet 9B, veins 2rs-m and 3rs-m meeting RS separately) present in many Cryptopimpla species has been reported (Townes 1969;Sheng 2011;Takasuka et al. 2011) to be a character state that is constant for all Afrotropical Cryptopimpla species (Reynolds Berry and van Noort 2016). In Syzeuctus and Atropha, the areolet is triangular with a long stalk and in Lissonota the areolet, when closed, is nearly always petiolate (i.e., dorsal aspect pointed, veins 2rs-m and 3rs-m meet before RS, couplet 10c; Townes 1969).
3. Mesopleuron compressed in Exetastes Group: Tetractenion and Exetastes species have stocky bodies with the mesopleuron laterally compressed (higher than wide) and often flat whereas in Atrophini the mesopleuron is usually wider than high (dorsoventrally compressed, couplet 4B, b).
4. Distinguishing Tossinola: the length of the ovipositor sheath relative to the hind tibia has previously been used as an additional character to separate Tossinola from the other Afrotropical genera in the tribe Atrophini where the areolet is open (Townes and Townes 1973). However, the relative lengths overlap across Lissonota, Cryptopimpla and Tossinola species, making it an unreliable character to separate these genera. While a medially, broadly interrupted occipital carina is still the most diagnostic character for the genus Tossinola, another useful character is the state of the apex of the submetapleural carinae: tooth-like in Tossinola (Townes 1969) but rounded in the other Afrotropical banchine genera. 5. Flagellum apically tapered: as observed by Townes (1969), the flagella of the genera Lissonota and Himertosoma are not, or may only be weakly, apically tapered. For Cryptopimpla and Spilopimpla species, the flagella are tapered to a slender apex (couplet 8 A, a; Townes 1969; Reynolds Berry and van Noort 2016).
6. Distinguishing Cryptopimpla: аll Afrotropical Cryptopimpla possess a first tergite that is evenly and rather strongly narrowed toward the base (couplet 9A; Reynolds Berry and van Noort 2016). In addition, the ovipositor sheath ca. 0.6× as long as the hind tibia is diagnostic of Cryptopimpla species (couplet 9C; Reynolds Berry and van Noort 2016).
7. Distinguishing Himertosoma from Lissonota: the absence of a crease separating the fifth laterotergite from the fifth metasomal tergite has been suggested as the single defining character that separates Himertosoma from Lissonota (couplet 10A, a; Watanabe and Maeto 2012). However, this does not appear to be a defining character for Afrotropical Lissonota species as the absence/presence of the crease varies within and among species. Given that the areolet can also sometimes be open in Lissonota species, assessment of the sculpture of the first metasomal tergite is required to separate Lissonota from Himertosoma. Himertosoma species nearly always have longitudinal striae present whereas Lissonota species rarely possess either strong punctures or longitudinal striae (couplet 10B, b; Townes 1969).
8. Length of the mandibular teeth: in the global description of the genus Exetastes by Townes (1969), he noted that the length of the lower mandibular tooth relative to the upper could be either equal or slightly longer/shorter. "Slightly" is a poor character description, especially concerning mandibular teeth, which wear out throughout the wasp's life. In the description of the genus, based on Costa Rican species, by Gauld et al. (2002), all species had equal mandibular teeth. Relative length of the mandibular teeth is a more reliable character, if one of the teeth is markedly longer or shorter. For example, in Afrotropical Cryptopimpla the upper tooth is distinctly longer than the lower tooth (Reynolds Berry and van Noort 2016). Similarly, it has been previously noted (Townes 1969), and further corroborated during this revision of Tetractenion, that the upper mandibular tooth is distinctly shorter in all species, making it a diagnostic feature for the genus. While most Afrotropical Exetastes have equal mandibular teeth, Exetastes discretus (Morley 1917) and an undescribed species in SAMC has mandibles with the lower tooth distinctly longer than the upper. This warrants further investigation, because these two genera are closely related, as they both form part of the Exetastes group. This character may represent a transition between the two genera.
9. Clypeus apically invaginated: this is a diagnostic feature of Tetractenion, while in Afrotropical Exetastes, as has been observed in other species, the clypeal edge is convex or straight, without a median indentation (Gauld et al. 2002).

Tetractenion Seyrig, 1932
Tetractenion Seyrig, 1932 Differential diagnosis. Tetractenion acaule is immediately distinguishable from all other Tetractenion species by its unique color combination of a red mesosoma and a mostly black metasoma; distinct keels are present on outer mesoscutal lobes, the notauli do not reach the scutellum; metasomal tergite I has a distinct medial compression in the dorso-ventral view, tergite II have distinct gastrocoeli, and tergites IV-VIII are dorso-posteriorly weakly sclerotized, appearing as large membranous white areas on the dorsal surface. Tetractenion acaule closely resembles T. ibayaensis as both species are similar in color, having largely fulvous bodies with a white face and the hind femur infuscate, whereas the remaining Tetractenion species are largely yellow in color with yellow hind femora. Tetractenion acaule can easily be distinguished from T. ibayaensis by having a white gena and weakly sclerotized metasomal tergites IV-VIII; the head is narrow, straight behind the eyes; a distinct carina is present on the pronotal collar; distinct keels are present on the outer mesoscutal lobes, with the notauli not reaching the scutellum; pits on the mesopleuron and propodeum are shallow; metasomal tergite I is distinctly dorso-medially compressed; gastrocoeli on tergite II are distinct; tergites IV-VIII are postero-dorsally weakly sclerotized and white; and tarsal claws on the hind leg are simple. In T. ibayaensis the gena is brown and tergites IV-VIII are strongly sclerotized; the head is rounded behind the eyes; with no more than a wrinkle present on the pronotal collar; the mesoscutal lobes are hardly present, the notauli reach the scutellum; pits on the mesopleuron and propodeum are deep; metasomal tergite I is stout and indistinctly dorso-ventrally compressed in the medial region; gastrocoeli on tergite II are indistinct; and tarsal claws on the hind legs are pectinate.
Description (updated from Seyrig 1932). Size 9-11 mm. Color: head white with a large black central area on occiput, reaching eyes on vertex and pointed on frons; antenna black, without pale ring; mesosoma red; metasomal tergites I and II red, though tergite II sometimes brownish, following tergites black with large membranous white areas from tergite IV; legs red, hind femur, tibia and tarsus infuscate; wings with sparse microtrichia, venation brown, pterostigma brown and centrally translucent reddish. Head narrow, straight behind eyes; occiput deeply and angularly excavated, occipital carina strong, extending to lower gena at base of mandible; eyes very large; malar space almost half as long as mandibular basal width; face and clypeus finely, evenly and rather sparsely punctate on a shiny background; face with three lobes, tentorial pits deep; clypeus small, laterally convex with declivity, apically invaginated, with clypeal edge convex; mandibular teeth triangular, lower tooth longer than upper tooth; antenna long, slender and apically tapered.
Mesosoma stout; mesonotum deeply punctate, inter-punctuate spaces about as wide as punctures, rather matt, but not coriaceous; keels distinctly raised on outer mesoscutal lobes of mesoscutum, notauli abbreviated, not reaching the scutellum; apex of scutellum rounded; pronotum shining with a distinct thickened carina on collar, sparsely and very finely punctate; mesopleuron higher than wide, sparsely but more deeply punctate, speculum similarly punctate, background hardly shining, epicnemial carina ending at anterior edge of mesopleuron; shallow pits on mesopleuron and propodeum; metapleuron matt and deeply punctate; propodeum weakly convex, roughly punctate dorsally, punctate posteriorly confluently grading into transverse wrinkles, posterior transverse carina reduced, lateral longitudinal carinae present but faint, spiracle roundish-elliptic and small.
Metasoma hardly punctate at base of tergite II, indistinctly punctate beyond base; tergite I elongate, more than twice as long as wide, tapered anteriorly, glymma present, spiracle positioned slightly in front of middle and protruding, especially dorsally, with a distinct medial depression dorso-ventrally; tergite II longer than wide or subquadrate with gastrocoeli distinct; tergite III quadrate to transverse; metasomal tergites IV-VIII moderately laterally compressed; ovipositor sheath concealed or hardly protruding.
Fore wing without ramellus on Rs-M vein; Rs hardly sinuate; areolet large and quadrate with a short stalk receiving 2m-cu at center. Hind wing with Cu1 shorter than cu-a such that Cu2 arises above the middle of these combined veins. Legs very long; hind femur reaching beyond metasomal apex; length of tibia III plus tarsus III as long as body; spurs of tibia III longer than half metatarsal length; tarsal claws on hind leg simple.
Male hardly different: temples a bit less narrowed behind eyes, metasomal tergite II entirely black.
The head is rounded behind the eyes distinguishing the species from T. acaule and T. pascali. The pronotal collar is no more than a wrinkle, separating the species from T. acaule and T. rosei. Pectinate tarsal claws on the hind legs separates the species from T. acaule and T. luteum. Metasomal tergites II and III are quadrate separating the species from all other Tetractenion species except T. acaule where tergites II and III are sometimes subquadrate and quadrate, respectively; and T. luteum where tergite III is quadrate. Sparse microtrichia on the wings distinguishes T. ibayaensis from T. luteum and T. pascali, and the pterostigma is brown separating the species from T. luteum, T. pascali, T. rosei, and T. pseudolutea.
Description. Body mostly fulvous; tibia and tarsus III brown; metasomal tergites IV-VIII brown to nearly black; head with face and area around eyes white; frons and occiput dark brown to near black; mandibles yellow with base and tips brown. Sparse microtrichia on wings, venation and pterostigma brown.
Head rounded behind eyes; occiput deeply and angularly excavated, occipital carina strong, extending to lower gena at mandibular base; malar space half as long as mandibular basal width; eyes very large; face and clypeus finely and evenly punctate on a shiny background; face with three lobes, tentorial pits deep; clypeus small, laterally convex with declivity, apically invaginated, clypeal edge convex; mandibular teeth triangular, lower tooth longer than upper tooth; clypeal and mandibular setae long; antenna long, slender and apically tapered.
Mesosoma stout and deeply punctate on a shiny background; mesopleuron higher than wide, epicnemial carina ending at anterior edge of mesopleuron; deep pits on the mesopleuron and propodeum; pronotum moderately punctate on a shiny background with no more than a wrinkle on collar; mesososcutal lobes hardly present on mesoscutum, notauli posteriorly meeting before reaching the scutellum; propodeum weakly convex, posteriorly confluently grading into weak transverse wrinkles, posterior transverse carina indistinct, lateral longitudinal carinae reduced, spiracle small and circular.
Metasoma with tergite I stout, tapered anteriorly, not distinctly dorso-ventrally compressed in medial region, glymma present, spiracle positioned in front of middle and protruding, especially dorsally, hardly punctate dorso-laterally, metasoma indistinctly punctate beyond and shining; gastrocoeli on tergite II indistinct; tergites II and III quadrate, tergites IV-VIII only slightly higher than wide.
Fore wing without ramellus on Rs-M vein; areolet large and quadrate with a short stalk receiving 2m-cu at center. Hind wing with Cu1 shorter than cu-a such that Cu2 arises above the middle of these combined veins. Legs very long; hind femur reaching beyond metasomal apex, length of tibia III plus tarsus III as long as body; spurs of tibia III longer than half metatarsal length; tarsal claws pectinate.  Ibadan, 9.9.1953, Coll. G.H. Caswell, P49 (NHMUK). Differential diagnosis. Tetractenion luteum is immediately distinguishable from the other species in the genus as this species is the only yellow-colored Tetractenion species to possess simple hind tarsal claws, and this character is consistent in both sexes. The head is rounded behind the eyes, distinguishing the species from T. acaule and T. pascali. The malar space nearly as long as the width of the base of the mandible separates T. luteum from T. acaule, T. pseudolutea, and T. ibayaensis. The pronotal collar is weakly wrinkled, separating the species from T. acaule and T. rosei. Metasomal tergite II is longer than wide and distinguishes the species from T. ibayaensis; and a quadrate tergite III separates T. luteum from T. pseudolutea, T. pascali, and T. rosei. Furthermore, T. pascali is the only other species that possess dense microtrichia on the wings. Description (updated from Seyrig 1935). Size 7.6-10.4 mm. Color: head yellow with black marking on occiput to middle of frons, no contact with eyes on vertex; meso-and metasoma, fore and mid legs uniformly yellow, hind leg mostly yellow with shades of infuscation on tibia and tarsus infuscate; wings with dense microtrichia, venation brown, pterostigma yellow.
Head with temple short, rounded behind eyes; occiput deeply and angularly excavated, occipital carina strong, extending to lower gena at base of mandible; eyes very large, malar space a bit shorter than width of mandibular base; face and clypeus finely, evenly and rather sparsely punctate on a matt background; face with three lobes, tentorial pits deep; clypeus small, laterally convex with declivity, apically invaginated, with clypeus edge convex; mandibular teeth triangular, lower tooth longer than upper tooth; antenna about as long as body, slender and apically tapered.
Mesosoma stout, matt to sub-polished; pronotum finely punctate on a sub-polished background, no more than a wrinkle present on pronotal collar; mesoscutum moderately punctate, mesoscutal lobes hardly present, notauli posteriorly meeting before reaching the scutellum; mesonotum and mesopleuron finely punctate; mesopleuron higher than wide, epicnemial carina ending at anterior edge of mesopleuron; shallow pits on mesopleuron and propodeum; propodeum weakly convex, matt to subpolished, moderately punctate posteriorly confluently grading into transverse wrinkles, posterior transverse carina reduced, lateral longitudinal carinae present but faint, spiracle small and circular-elliptical.
Metasoma with a sub-polished background, anterior half of tergite I and dorso-lateral region of tergite II hardly punctate, indistinctly punctate beyond base; tergite I twice as long as wide, glymma present, tapered anteriorly, weak to indistinctly dorso-ventrally depressed in the medial region, spiracle positioned in front of middle and protruding, especially dorsally; tergite II longer than wide, gastrocoeli indistinct; tergite III quadrate.
Fore wing with ramellus absent on Rs-M vein; areolet large and quadrate with a short stalk receiving 2m-cu at center. Hind wing with Cu1 shorter than cu-a such that Cu2 arises above the middle of these combined veins. Legs very long; hind femur reaching beyond metasomal apex, length of tibia III plus tarsus III as long as body, spurs of tibia III longer than half metatarsal length; fore and mid tarsal claws pectinate, hind tarsal claws simple.
Distribution. Democratic Republic of Congo, Kenya, Namibia, Nigeria, and South Africa. Differential diagnosis. Tetractenion pascali is immediately distinguishable from all other Tetractenion species by having a color combination of a largely yellow body and a dark head. The facial features are more robust compared to the other species, with the three lobes on the face prominent and the mandibles larger, and the spiracle on the second tergite of the metasoma is hardly protruding. In addition, though the posterior transverse carina may be reduced or faint in the other species, it is distinct in T. pascali. The malar space nearly as long as the width of the mandibular base separates T. pascali from T. acaule, T. pseudolutea, and T. ibayaensis. Pectinate hind tarsal claws distinguish T. pascali from T. luteum and T. acaule; and a weakly wrinkled pronotal collar separates the species from T. acaule and T. rosei. Metasomal tergites II and III are longer than wide separating the species from T. ibayaensis and T. acaule, T. luteum, and T. ibayaensis, respectively. Tetractenion luteum is the only other species besides T. pascali that possess dense microtrichia on the wings. Description. Color: head brown, mandibles yellow from base to brown at apex. Antennae brown. Body yellow with red-brown areas on metanotum; tibia III with shades of infuscation, tarsus III infuscate. Wings with dense microtrichia, pterostigma yellow, venation brown.

Tetractenion pascali Reynolds Berry & van
Head narrowed straight behind eyes; occiput deeply and angularly excavated, occipital carina strong, extending to lower gena at mandibular base; malar space nearly as long as basal mandibular width; eyes very large; face and clypeus features robust, mandibles large; face three-lobed and punctate on a shiny background, punctures on second lobe and clypeus deeper than punctures on lobes flanking eyes, tentorial pits deep; clypeus small, laterally convex with declivity, apically invaginated, clypeal edge convex; mandibular teeth triangular, lower tooth longer than upper tooth; antenna long, slender and apically tapered.
Mesosoma stout and moderately punctate on a shiny background; pronotum with no more than a wrinkle on collar; mesoscutal lobes present on mesoscutum, notauli posteriorly meeting before reaching the scutellum; mesopleuron higher than wide, epicnemial carina present at ending at anterior edge of mesopleuron; shallow pits on mesopleuron and propodeum. Propodeum weakly convex, punctate and posteriorly confluently grading into transverse wrinkles, posterior transverse carina present and distinct, lateral longitudinal carinae present but faint, spiracle small and circular-elliptical.
Metasoma indistinctly punctate on a shiny background; tergite I elongate, twice as long as wide, tapered anteriorly, dorso-ventrally compressed in the medial region, glymma present, spiracle positioned in front of middle and hardly protruding; tergite II longer than wide, gastrocoeli indistinct; tergite III longer than wide; tergites IV-VIII higher than wide.
Fore wing without ramellus on Rs-M vein; areolet large and quadrate with a short stalk receiving 2m-cu at center. Hind wing with Cu1 shorter than cu-a such that Cu2 arises above the middle of these combined veins. Legs very long, hind femur reaching beyond metasomal apex, length of tibia III plus tarsus III as long as body; spurs of tibia III longer than half metatarsal length; tarsal claws pectinate.
Etymology. Named after our colleague, Pascal Rousse, who first noted this to be a new species.
Distribution. Namibia and South Africa. Comments. In males, the ramellus on the fore wing is present, distinguishing the species from T. acaule and T. luteum. The wings of T. rosei are inter-locked; this character could not be compared. Differential diagnosis. While the color pattern of Tetractenion pseudolutea is identical to T. luteum, it is distinguishable from T. luteum by having pectinate tarsal claw on the hind leg. The head is rounded behind the eyes, separating the species from T. acaule and T. pascali. The pronotal collar with no more than a wrinkle present distinguishes the species from T. acaule and T. rosei. Pectinate tarsal claws on the hind leg separates T. pseudolutea from T. acaule and T. luteum. Metasomal tergites II and III are longer than wide distinguishing T. pseudolutea from T. ibayaensis; and T. acaule, T. luteum, and T. ibayaensis, respectively. Sparse microtrichia on the wings distinguishes the species from T. luteum and T. pascali; yellowish-brown venation separates the species from T. acaule, T. luteum, T. ibayaensis and T. pascali; and a yellow pterostigma distinguishes the species from T. acaule and T. ibayaensis. Description. The body color is the same as in Tetractenion luteum, except for density of microtrichia on the wings. Tetractenion pseudolutea has sparse microtrichia on the wings with yellow-brown venation, and the pterostigma is yellow.

Tetractenion pseudolutea
Head is rounded behind eyes; occiput deeply and angularly excavated, occipital carina strong, extending to lower gena at base of mandible; eyes very large, malar space more than half as long as wide as base of mandible; face and clypeus finely and evenly punctate, background hardly shining; face with three lobes, tentorial pits deep; clypeus small, laterally convex with declivity, apically invaginated, clypeal edge convex; mandibular teeth triangular, lower tooth longer than upper tooth; antennae long, slender and apically tapered.
Mesosoma stout; mesoscutum deeply punctate, mesoscutal lobes hardly present, notauli posteriorly meeting before reaching the scutellum; pronotum finely punctate on a shiny background, no more than a wrinkle present on collar; mesopleuron and mesonotum finely punctate; mesopleuron higher than wide, epicnemial carina ending at anterior edge of mesopleuron; pits on mesopleuron and propodeum are shallow; propodeum weakly convex, finely punctate, posteriorly confluently grading into transverse wrinkles, posterior transverse carina reduced, lateral longitudinal carinae present but faint, spiracle small and circular-elliptical.
Metasoma indistinctly punctate on a shiny background; tergite I twice as long as wide, tapered anteriorly, sometimes weakly dorso-ventrally depressed in the medial region, glymma present, spiracle positioned in front of middle and protruding, especially dorsally; tergite II longer than wide, gastrocoeli indistinct; tergite III longer than wide; tergites IV-VIII moderately laterally compressed.
Fore wing with ramellus rarely present on Rs-M vein; areolet large, quadrate, with a short stalk receiving 2m-cu at the center. Hind wing with Cu1 shorter than cu-a such that Cu2 arises above the middle of these combined veins. Legs very long, hind femur reaching beyond metasomal apex, length of tibia III plus tarsus III as long as body, spurs of tibia III longer than half metatarsal length; tarsal claws pectinate. CT 2.3; ML 0.6; IO 0.9-1.0; OO 1.7; Fl 1 4.6-5.6; OT 0.1; B 9.1-10.7 mm; A 11.3-11.8 mm; F 8.6-9.8 mm.
Etymology. This species at first glance appears to be identical in coloration to T. luteum but has morphological differences.
Distribution. Angola, Cameroon, Namibia, and South Africa. . Differential diagnosis. Tetractenion rosei is immediately distinguishable from other Tetractenion species by the reddish color of the head and pronotum in combination with a yellow body, completely yellow legs with venation on the wings also yellow. The head is not narrowed straight behind the eyes but rather rounded, distinguishing the species from T. acaule and T. pascali. The malar space nearly as long as the basal mandible width separates T. rosei from T. acaule, T. pseudolutea, and T. ibayaensis. Tetractenion acaule is the only other species besides T. rosei possessing a thickened and well-defined carina on the pronotal collar.
Pectinate hind tarsal claws separate the species from T. acaule and T. luteum. Sparse microtrichia on the wings distinguishes the species from T. luteum and T. pascali, and the pterostigma is yellow distinguishing the species from T. acaule and T. ibayaensis. Metasomal tergites II and III are longer than wide separating T. rosei from T. ibayaensis; and T. acaule, T. luteum, and T. ibayaensis, respectively.
Description. Color: head and pronotum reddish, black area restricted to region of ocelli. Body, legs, antennae yellow. Wings with sparse microtrichia, venation yellow, pterostigma yellow.
Head rounded behind eyes; occiput deeply and angularly excavated, occipital carina strong, extending to lower gena at mandibular base; malar space nearly as long as basal mandibular width; eyes very large; face and clypeus moderately and evenly punctate on a shiny background; face with three lobes, tentorial pits deep; clypeus small, laterally convex with declivity, apically invaginated, clypeal edge convex; mandibular teeth triangular, lower tooth longer than upper tooth; antenna long, slender and apically tapered.
Mesosoma stout with a shiny background; mesopleuron moderately punctate, epicnemial carina ending at anterior edge of mesopleuron; pits on the mesopleuron and propodeum shallow; mesonotum moderately punctate; pronotum sparsely and finely punctate on a shiny background with a well-defined carina on collar; mesoscutum deeply punctate, mesoscutal lobes hardly present, notauli posteriorly meeting before reaching the scutellum; propodeum weakly convex, deeply punctate posteriorly confluently grading into transverse wrinkles, posterior transverse carina indistinct, lateral longitudinal carinae present, spiracle small and round.
Metasoma indistinctly punctate on a shiny background; tergite I more than twice as long as wide, tapered anteriorly, slight dorso-ventral depression in medial region, glymma present, spiracle in front of middle and protruding; tergites II and III longer than wide; gastrocoeli on tergite II indistinct; tergites IV-VIII higher than wide.
Hind wing with Cu1 shorter than cu-a such that Cu2 arises above the middle of these combined veins. Legs very long, hind femur reaching beyond metasomal apex, length of tibia III plus tarsus III as long as body, spurs of tibia III longer than half metatarsal length; tarsal claws pectinate. CT 1.6; ML 0.9; IO 1.4; OO 2.2; Fl 1 3.5; B 9.3 mm; F 8.6 mm.
Etymology. Named because of the reddish color of the head and pronotal collar. Noun in apposition.

Distribution. Cameroon.
Comments. This is a rare species known only from one female specimen. Sampling in other areas of the Afrotropical region has so far not produced any further specimens. The wings are inter-locked in such a way that a useful diagnostic character of the wings cannot be seen, i.e., whether the ramellus is present or not.

Discussion
Since publication of the first key to genera of Banchinae in the Afrotropical region (Townes and Townes 1973), new knowledge on the subfamily has been acquired and there have been recent technological advances allowing for production of good quality images to illustrate relevant diagnostic character states. The revised and updated key is now more user-friendly. The genus Tetractenion was previously represented by two species and the present study has yielded an additional four species restricted to the Afrotropical region. Representative specimens in world collections remain rare and apart from those that are housed in the NHMUK and the CASC only; to our knowledge, there are no additional historical specimens present in world collections.
The general habitus and coloration of Tetractenion species suggest that this is possibly a nocturnal genus. A list of characters associated with being nocturnal or crepuscular includes a general brown-yellow color; long antennae; large eyes and large ocelli (Gauld and Huddleston 1976;Warrant et al. 2004;Greiner 2006). In addition, most species with this suite of characters are koinobionts (Quicke 2015). The benefit of being a koinobiont nocturnal species is that these parasitoid wasps are able to access hosts that are hidden during the day; many caterpillars conceal themselves during the day and come out to feed at night (Quicke 2015). Diurnal wasps, on the other hand, are faced with the pressures of predation and competition for limited resources (Warrant 2008). Where known, all Banchinae are koinobiont endoparasitoids of Lepidopteran caterpillars (Gauld and Mitchell 1978;Gauld et al. 2002;Fernandes et al. 2010;Broad et al. 2011;Tschopp et al. 2013). Tetractenion species possess very large eyes and long antennae relative to body size (A = 8.1-14 mm, B = 7.6-11.5 mm). However, the ocelli were not found to be particularly large (IO = 0.9-1.6, OO = 1.6-2.2); i.e., an ocellus with a large diameter would result in IO and OO indices with values less than one. Like other members of the Banchinae tribe Banchini, Tetractenion have very short ovipositors to allow for attack on exposed caterpillars (Fitton 1985(Fitton , 1987. Members of the tribes Glyptini and Atrophini have ovipositors about as long as or longer than the metasoma and exploit semi-to -concealed hosts in leaf rolls, tunnels, buds, etc. (Townes 1969;Quicke 2015). This provides further support that the genus may have evolved to utilize host resources not readily available during the day. Given the endemicity to the Afrotropical region, Tetractenion is also predicted to be a more derived genus within the subfamily Banchinae. Phylogenetic analyses of the subfamily within the Afrotropical region established that the tribe Banchini (only the Exetastes group is present in the Afrotropical region), represented by T. pascali and two Exetastes species, to be the most derived of the three tribes present in the region (Reynolds Berry 2019). Dating of the genus Tetractenion could not be determined based on a single species, but given that Exetastes has a cosmopolitan distribution and Tetractenion is an African endemic it is likely that Tetractenion is the more derived of the two genera.
Although there have been recent comprehensive long-term inventory surveys conducted across many parts of Africa with many rich, recently collected bulk samples that still need to be sorted, in reality, comprehensive sampling of Ichneumonidae in the region has been relatively limited to specific areas (Hopkins et al. 2019a(Hopkins et al. , 2019bKlopfstein et al. 2019;van Noort 2019). The perceived rarity (two species represented by a single specimen) of Tetractenion suggests that, with implementation of further rigorous inventory surveys across the many inadequately sampled areas of Africa, there are still more Tetractenion species to be discovered. Due to the relatively limited availability of specimens within this genus, any assessments of the distribution and diversification of the different species are still likely to be biased. This is corroborated by new locality records presented in this paper demonstrating bias in previously recorded distributional data: T. luteum was previously recorded from the Democratic Republic of Congo and Kenya (Seyrig 1935;Yu et al. 2020), but additional records from southern Africa suggest that this species probably has a more widespread distribution across Africa.
Most of the species have the pro-, meso-, and meta-tarsal claws pectinate to the apex. Tetractenion luteum and T. acaule (a Madagascan endemic) are the only two species that possess simple tarsal claws on the hind leg. While the overall color patterns of T. pseudolutea are identical to T. luteum, it is readily distinguishable from T. luteum by having a pectinate tarsal claw on the hind leg. With most Tetractenion species having pectinate tarsal claws on the hind leg, it is plausible that this character state is the plesiomorphic condition. Based on the assumption that it is more parsimonious for evolutionary trajectories to proceed via the reduction of morphological characters, rather than evolution of more complex character states, T. luteum and T. acaule are most probably the more derived species within the genus, but this hypothesis requires corroboration with the addition of genetic evidence, and a thorough phylogenetic analyses based on both morphological and molecular characters.
The current revision has increased the species richness of the genus threefold. Further comprehensive sampling will undoubtedly uncover additional Tetractenion species in the Afrotropical region.
(National Research Foundation) grants: GUN 2068865; GUN 61497; GUN 79004; GUN 79211; GUN 81139; GUN 98115. Part of the South African field work conducted by SvN was funded by the National Science Foundation under PlatyPBI grant no. DEB-0614764 to N.F. Johnson and A.D. Austin. Cape Nature; the Eastern Cape Department of Environmental Affairs and the Northern Cape Department of Nature and Environmental Conservation provided collecting permits for South Africa. This study also benefited from generous contributions of banchine material from the following sources: NHMUK and CASC loaned specimens used in this study; additional specimens were donated to the Iziko South African Museum by Drs. Mike Mostovski and Alec Gumovsky; and the bulk of specimens were collected by SvN. Past and present members of the Research and Exhibitions Department at the Iziko South Africa Museum, particularly to Dr. Pascal Rousse, Aisha Mayekiso Rayners, Tiyisani Chavala, and Victor Mutavhatsindi are also thanked for their assistance with a variety of issues pertaining to curating. We are grateful to Prof. Mabel Alvarado and Dr. Gavin Broad for their positive and helpful review on the manuscript.