354 Invasive Stink Bugs and Related Species (Pentatomoidea)
7.2 Taxonomy
Amyot and Serville (1843) proposed the genus Nezara in the group ‘Rhaphigastrides’ to include Cimex
smaragdulus F. (= viridulus L.) and Pentatoma marginata Palisot de Beauvois. Several taxa were
described and included in the genus over the subsequent decades (Freeman 1940), but most of them have
been transferred to other genera or are recognized currently as synonyms. In the last world catalogue
of the family Pentatomidae, Kirkaldy (1909) recognized six subgenera in Nezara, all of which are now
considered as separate genera (Bergroth 1914, Freeman 1940, Day 1964, Orian 1965, Linnavuori 1972,
Thomas and Yonke 1981, Rolston 1983, Grazia and Fortes 1995, Schwertner and Grazia 2007). The revi-
sion by Freeman (1940) firmly established the limits of the genus, recognizing 11 species and 21 variet-
ies. Currently, 12 species are considered valid (Ferrari et al. 2010).
A hypothesis of phylogenetic relationship within Nezara was proposed by Ferrari et al. (2010). A basal
dichotomy splits the genus into two clades, with N. viridula belonging to the clade that also includes
N. antennata and N. yunnana. A close relationship between viridula and antennata also was shown by
morphological similarity and interspecific mating behavior (which, actually, does not result in viable
progeny) (Freeman 1940; Kiritani et al. 1963; Kon et al. 1988, 1993, 1994). The species N. antennata and
N. yunnana are restricted geographically to the Oriental and southern Palearctic regions and associated
with tropical and subtropical climates. N. yunnana occurs from northern India to southern China, and
the type locality is Duanli, Yunnan, China. N. antennata is more widespread, having been recorded from
southern China, India, Japan, the Philippines, South Korea, and Sri Lanka (Rider 2006a).
Because of its color variability and wide geographical distribution, Nezara viridula has been the
subject of many taxonomic studies, resulting in several synonyms. The species has several ‘color
types’ (i.e., genetic morphs) of adults but two main morphs exist (i.e., numerically dominant in most
regions): var. smaragdula F. (G-type, completely green coloration) and var. torquata F. (O-type, pre-
dominantly green body with anterior yellowish coloration) (Figure 7.1E). Mating studies between var.
smaragdula and var. torquata yielded offspring with “an orange body like Y-type (f. aurantica [sic]
Costa) but a yellow band on the pronotum” (Ohno and Alam 1992) (Figure 7.1F). The so-called var.
aurantiaca Costa (Y-type) is all orange and rare (Figure 7.1G, at right) (e.g., less than 1% in Brazil
[Vivan and Panizzi 2002] and even less in other regions [Hokkanen 1986, Golden and Follett 2006]).
Several other color morphs have been recorded from different parts of the world, including a blue form
(Figure 7.1G, at left; Antônio R. Panizzi, personal communication). Additionally, Chen (1980, and
references therein) reported the occurrence of two other forms (N. viridula form duyuna Chen, n. f.,
and N. viridula form typica) in China. More recently, Esquivel et al. (2015) reported the occurrence
of a black morph (Figure 7.1H).
Different color morphs are found among established populations and do not justify separation at the
species level. However, genetic evidence has demonstrated spatially structured patterns of population
distribution and differentiation. Meglič et al. (2001) determined a certain amount of genetic difference
among geographically isolated populations between continents and Sosa-Gómez et al. (2005) and Vivan
and Panizzi (2006) within Brazilian populations. Pavlovčič et al. (2008) analyzed genetic variation
between European, North and South American, Asian, and African populations and found a widely dis-
tributed haplotype, but they also found an ancient lineage in Africa and a possible hybridization lineage
in Japan. Variation in genetic color polymorphism also appears to be spatially structured, with Japan
hosting the greatest diversity of variants; other regions often have only a single color morph prevailing
(Yukawa and Kiritani 1965). In any case, these color morphs should not be confused with environmen-
tally determined seasonal color variants that may occur before, during, and shortly after hibernation
(Figure 7.1D; also see Section 7.4.4 and Chapter 11).
Based on the distribution and frequencies of the color morphs, Yukawa and Kiritani (1965) proposed
the origin of Nezara viridula to have been in southwest Asia. Hokkanen (1986) and Jones (1988), based
on a more complete data set including parasitoids and ecological characteristics, considered the origin
of N. viridula to have been in the Ethiopian biogeographical region of Africa. More recently, Kavar
et al. (2006) sequenced 16S and 28S rDNA, cytochrome B and cytochrome C oxidase subunit I gene
fragments and random amplified polymorphic DNA (RAPD) from geographically separated locations