Pleurochrysis Bohart, 1966

The case of Pleurochrysis Bohart, 1966 View in CoL

Guérin-Méneville (1842) described Chrysis (Pleurocera) viridis Guérin-Méneville, 1842 , nec Olivier, 1790 currently Chrysis bruchi Brèthes, 1903 , based on the specimen photographed by PR at MSNG ( Figs 9A, 9C View FIGURE 9 ) and characterised by flabellate antennae. Pleurocera was later used as a valid genus by Brullé (1846) and Linsenmaier (1959) and as a subgenus of Chrysis by Bodenstein (1939) and of Neochrysis Linsenmaier, 1959 by Bohart (1966) who recognised that Pleurocera is a junior homonym of Pleurocera Rafinesque, 1818 ( Gastropoda, Pleuroceridae ) and replaced it with Pleurochrysis . It was later re-raised to genus rank by Kimsey (1985) and treated as such by Kimsey & Bohart (1991). Conversely, Linsenmaier (1985, 1997) considered Pleurocera as a subgenus of Neochrysis . Moreover, Linsenmaier (1985), in his revision of the genus Neochrysis , described two other subgenera: Brethesia Linsenmaier, 1985 nec Schrottky, 1909 ( Hymenoptera , Pompilidae ) and Exsecochrysis Linsenmaier, 1985 . Overall, he recognised five subgenera of Neochrysis : Neochrysis s.str.; Brethesia Linsenmaier, 1985 ; Exsecochrysis Linsenmaier, 1985 ; Ipsiura Linsenmaier, 1959 ; and Pleurochrysis Bohart, 1966 .

Almost simultaneously, but with priority of a month, Kimsey (1985) and Bohart (1985) elevated Ipsiura and Pleurochrysis to genus rank, along with Exochrysis Bohart, 1966 , whose species were included within the spinigera group of subgenus Neochrysis by Linsenmaier (1985). Later, Linsenmaier (1987) replaced the name of Brethesia Linsenmaier, 1985 nec Schrottky, 1909 with Brethesiella Linsenmaier, 1987 , which in turn is an invalid name, being a junior homonym of Brethesiella Porter, 1920 and Brethesiella Timberlake, 1920 ( Hymenoptera , Encyrtinae), these later replaced by Boffachrysis Pagliano & Scaramozzino, 1990 . Kimsey & Bohart (1991) synonymized Exsecochrysis and Brethesiella Linsenmaier with Pleurochrysis .

Rosa et al. (2023) noted that Pleurochrysis Bohart, 1966 was also invalid, being a junior homonym of Pleurochrysis Pringsheim, 1955 originally described as Flagellate (see Rosa et al. (2023) for details). Consequently, Pleurochrysis Bohart was replaced by Rhipidochrysis Rosa & Pavesi in Rosa et al. (2023), with Chrysis viridis Guérin-Méneville, 1842 designated as its type species by automatic designation. Lucena et al. (2024) acknowledged that the name Pleurochrysis Bohart is invalid, but synonymized Rhipidochrysis with Exsecochrysis , asserting that this was the first available name among the synonyms of Pleurocera in accordance with Code Art. 60.2.

Being a technical article, Rosa et al. (2023) focused only on objectively invalid names of chrysidid genera, without entering into taxonomic and phylogenetic details. In this sense, they failed to explain the reasons for keeping Rhipidochrysis separated from the other Neotropical genera. The authors agreed with Linsenmaier (1985, 1997) and Bohart (1966) that this genus (subgenus in Linsenmaier’s classification) includes only the type species, Chrysis viridis Guérin-Méneville, 1842 currently Rhipidochrysis bruchi ( Brèthes, 1903) , characterized by the apical margin of the third tergum with six teeth and by the flabellate male flagellomeres.

Although Exsecochrysis Linsenmier, 1985 was originally considered to be a distinct subgenus with a different type species, Neochrysis gracilia Linsenmaier, 1985 , it was treated as a subjective synonym of Pleurochrysis by Kimsey & Bohart (1991). However, Linsenmaier (1997) did not follow the classification proposed by the American authors and continued to consider Exsecochrysis and “ Pleurochrysis ” as distinct. Rhipidochrysis bruchi and members of Exsecochrysis , in our opinion, truly belong to different genera following the generic criteria proposed by Kimsey & Bohart (1991) for Chrysidini genera, that should be applied in this case as well. For example, some key diagnostic traits observed in Exsecochrysis , such as the highly reduced wing venation ( Fig. 9B View FIGURE 9 ), the absence of the transverse frontal carina ( Fig. 9E View FIGURE 9 ), and the shape of the male flagellomeres ( Fig. 9E View FIGURE 9 ), are otherwise regarded as valid criteria for genus differentiation, e.g. in Chrysidea Bischoff, 1913 and Chrysura Dahlbom, 1845 , but were disregarded in the case of Exsecochrysis .

The diagnostic characters of Exsecochrysis sensu Linsenmaier (1985 , 1997) are well defined. The four known species share the following traits: small body size, 3.5–5.0 mm; wings with reduced venation, including faint veins Cu, Rs+M, m-cu, Cu1 and barely visible A1 ( Fig. 9B View FIGURE 9 ); Rs thick, short, as long as stigma, with second half appearing as a narrow vein ending more than 2 × MOD from wing margin ( Fig. 9B View FIGURE 9 ); discoidal cell faint; distal margin of fore wing rounded ( Fig. 9B View FIGURE 9 ); head profile round, with bulbous eyes and narrow, ventrally constricted scapal basin ( Fig. 9E View FIGURE 9 ); frons with large, irregular and contiguous punctures, without transverse frontal carina; antennal flagellum slender and cylindrical in both sexes ( Fig. 9E View FIGURE 9 ); pronotum without anteromedian sulcus; metanotum roughly as long as mesoscutellum or only slightly shorter; metasoma without longitudinal medial carina on second tergum; third tergum saddled in lateral view and bulging before pit row, pit row distinct with wide and deep pits, apical margin with four teeth, lateral margin with a more or less extended whitish spot; black spots on second sternum small and oval; legs largely yellowish on femur distal apex, on tibiae and tarsi.

Conversely, Rhipidochrysis has larger species,> 7.5 mm; wings with all veins fully developed and sclerotized ( Fig. 9A View FIGURE 9 ); Rs fully developed and sclerotized ending 1–2 × MOD from wing margin ( Fig. 9A View FIGURE 9 ); discoidal cell fully visible; distal margin of fore wing unmodified; head with subtriangular profile and wide scapal basin (compare also Figs 132a, 132b in Kimsey & Bohart 1991); frons with sculpture unmodified and frontal carina present; antennal flagellum dimorphic, flabellate in male ( Figs 9C, D View FIGURE 9 ), black and cylindrical in female; pronotum sulcate; metanotum half as long as mesoscutellum and medially longitudinally ridged; metasoma with weak fully impunctate longitudinal carina; third tergum unmodified, straight and only slightly bulging before pit row, pit row small and with shallow pits, apical margin with six teeth, lateral margin without whitish spot; black spots on second sternum large and rounded; legs fully metallic with black tarsi and basitarsi metallic ventrally.

Based on the above characters, especially the modified wing venation, the shape and sculpture of the head, the cylindrical and unmodified antennae of the male, and the small body size compared to Rhipidochrysis and also Boffachrysis , we consider Exsecochrysis Linsenmaier, 1985 to be a valid genus so far restricted to the species included by Linsenmaier (1985, 1997): E. alfkeni ( Ducke, 1902) ; E. adnexa ( Linsenmaier, 1997) ; E. allotria ( Linsenmaier, 1985) ; and E. gracilia ( Linsenmaier, 1985) . E. gracilia was synonynized with Chrysogona alfkeni Ducke, 1902 by Kimsey & Bohart (1991) without type examination, but it was revalidated by Linsenmaier (1997) who listed the main diagnostic differences. This revalidation was overlooked by Lucena et al. (2024) but the two species are clearly distinct as Linsenmaier (1997) stated, based on the characters discussed and illustrated below (see Exsecochrysis gracilia and Fig. 10 View FIGURE 10 ).

We consider Rhipidochrysis restricted to R. bruchi , whereas other species of “ Pleurochrysis ” are here considered members of Boffachrysis Pagliano & Scaramozzino, 1990 , not mentioned by Kimsey & Bohart (1991) and Lucena et al. (2024). Boffachrysis is the replacement name for Brethesiella Linsenmaier, 1997 nec Porter, 1920, nec Timberlake, 1920. The type species of Boffachrysis is Chrysis ameghinoi Brèthes, 1902 by automatic designation and this genus can be separated into two groups, likely distinct genera, but it temporarily includes all the other species included by Kimsey & Bohart (1991) in “ Pleurochrysis ” and is relatively heterogeneous, characterized by lack of derived characteristics. There are species, such as B. imbecilla ( Mocsáry, 1889) , that share some diagnostic characters with Exsecochrysis , e.g. structure and sculpture of the head, but do not share the same combination of diagnostic characters, such as the reduced wing venation. We agree with Kimsey (1985), Kimsey & Bohart (1991) and Lucena et al. (2024) that “ Pleurochrysis ” requires future studies to make their generic delimitations congruent with phylogenetic relationships, but meanwhile consider Exsecochrysis and Rhipidochrysis sufficiently characterised to be treated as separate genera.