Distinguishing Female Conostigmus and Dendrocerus, and matching males and females (Table 3)

As discussed above, it can be difficult to distinguish Dendrocerus males from Conostigmus males; in the case of females, it can be nearly impossible. Females of both genera have similar antennal, genitalia and ovipositor characters. Females of both genera also have more similar ocellar triangle shapes and POL vs. OOL ratios than males. Characters that do occur across both male and female specimens include the presence of the sternaulus (never present in Dendrocerus, absent or present in Conostigmus), notauli posterior end (always adjacent to transscutal articulation in Conostigmus, but not adjacent in some Dendrocerus) and wing presence (wings always present and macropterous in Dendrocerus). However, the numerous exceptions that exist prevent these characters from being applied to all species. Other characters such as facial pit presence, as well as more subjective characters such as metapleural sulcus shape, head shape and general habitus, can be useful but are more variable and should not be used independently to make generic identifications.

It is difficult to distinguish females of Conostigmus and Dendrocerus, let alone females of different Conostigmus species. Even males cannot always be differentiated by somatic characters alone, as demonstrated by the morphometric analysis with the shape PCAs. This revision relies mainly on male genitalia characters, as this can be the only way to distinguish Conostigmus species in some cases (Dessart, 1997a, 1997b; Mikó et al., 2013, 2016).

Some species do have unique combinations of somatic characters that can be used to match males and females, including C. muesebecki, C. dimidiatus, C. erythrothorax, C. nigrorufus, C. bipunctatus, C. triangularis, and C. lepus. We were also able to confirm the female of C. pulchellus based on a male specimen that exhibited the same coloration found in the female specimens, but we avoid redescribing females of C. abdominalis from the Nearctic, as this species can only be distinguished from C. rosemaryae using male genitalia characters. Several Nearctic Conostigmus species were described from single female type specimens, but because females cannot be identified to species in most cases, we consider these as species inquirenda. Advances in molecular taxonomy and future work rearing live Conostigmus males and females will shed more light on this subject, and we eagerly anticipate what will be found.